WO2025225328A1 - Waterproofing member - Google Patents

Abstract

This waterproofing member 10 is disposed so as to block an opening 51 of an object 50 that has an opening surface 51s where the opening 51 is formed. The waterproofing member 10 comprises a waterproofing film 1 that has a first principal surface 1a which faces the opening 51 when arranged so as to block the opening 51, and a second principal surface 1b which is on the opposite side from the first principal surface 1a. The waterproofing film 1 includes a body part 11 and particles 12 positioned more on the first principal surface 1a side than the body part 11. The first principal surface 1a of the waterproofing film 1 has a region R1a in which the arithmetic average height Sa is 0.20 μm or greater. The object 50 includes, for example, a micro-electromechanical system (MEMS).

Description

Waterproofing materials

The present invention relates to a waterproof member.

Electronic devices equipped with sound-related components (acoustic components) such as sound-producing units such as speakers and buzzers, and sound-receiving units such as microphones, include many portable devices used outdoors, such as wearable devices such as smartwatches, smartphones, mobile phones, and digital cameras. In recent years, there has been a demand for electronic devices equipped with such acoustic components to be waterproof while maintaining sound transmission properties. Waterproof smartwatches and waterproof smartphones are already widespread, and filters with waterproof sound transmission capabilities (waterproof sound-transmitting materials) are used to protect the acoustic parts (acoustic components) of these devices.

Conventionally, the use of microporous membranes made of polytetrafluoroethylene (PTFE) or the like has been proposed as waterproof sound-transmitting materials (see, for example, Patent Document 1). Furthermore, in recent years, waterproof protective cover members (waterproof members) have been proposed for placement over openings in microscopic products such as Micro Electro Mechanical Systems (MEMS) (see, for example, Patent Document 2).

Special Publication No. 2003-503991 Special Publication No. 2018-501972

When pressure such as water pressure is applied to a waterproofing component that is placed to cover an opening in a device or other device with an opening formed on its surface, the waterproofing membrane will deform. Deformation of the waterproof membrane due to the application of pressure can sometimes result in a decrease in the sound transmission characteristics of the waterproofing component.

The present invention therefore aims to provide a waterproofing member that is suitable for suppressing the deterioration of sound transmission characteristics caused by deformation of the waterproofing membrane due to the application of pressure.

The present invention provides
A waterproofing member that is disposed so as to close an opening of an object having an opening surface on which an opening is formed,
a waterproof membrane having a first main surface facing the opening when the waterproof membrane is disposed to close the opening and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
a waterproof member, wherein the first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more;
to provide.

From another aspect, the present invention provides a method for manufacturing a semiconductor device comprising:
A waterproof member disposed inside a microelectromechanical system (MEMS) including a substrate having an opening functioning as a sound vent, a MEMS die having a vibration plate, and a cap covering the MEMS die, the waterproof member comprising:
a waterproof membrane having a first main surface facing the diaphragm when the waterproof membrane is disposed so as to close the opening and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
a waterproof member, wherein the first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more;
to provide.

From yet another aspect, the present invention provides a method for manufacturing a semiconductor device comprising:
A waterproofing member that is disposed so as to close an opening of an object having an opening surface on which an opening is formed,
a waterproof membrane having a first main surface and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
The first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more,
When the waterproof membrane is disposed so as to close the opening, the first main surface or the second main surface of the waterproof membrane faces the opening.
Waterproofing materials,
to provide.

The present invention provides a waterproofing member that is suitable for suppressing deterioration in sound transmission characteristics caused by deformation of the waterproofing membrane due to the application of pressure.

FIG. 1 is a cross-sectional view schematically illustrating an example of a waterproofing member according to a first embodiment of the present invention. FIG. 2 is a perspective view schematically showing the waterproof member of FIG. FIG. 3 is a cross-sectional view showing an example of a state in which the waterproofing member of FIG. 1 is arranged to cover an opening of an object. FIG. 4A is a cross-sectional view schematically illustrating an example of a waterproof film included in the waterproof member of FIG. 1 . FIG. 4B is an enlarged partial view of FIG. 4A. FIG. 5 is a schematic cross-sectional view for explaining deformation of the waterproof film when water pressure is applied to the waterproof member in the state of FIG. FIG. 6 is a cross-sectional view schematically showing another example of the waterproof film provided in the waterproof member of FIG. FIG. 7 is a cross-sectional view schematically showing another example of the waterproof member of the present invention. FIG. 8 is a perspective view schematically showing the waterproof member of FIG. FIG. 9 is a cross-sectional view showing an example of a state in which the waterproofing member of FIG. 7 is arranged to cover an opening of an object. FIG. 10 is a schematic cross-sectional view for explaining deformation of the waterproof film when water pressure is applied to the waterproof member in the state of FIG. FIG. 11 is a cross-sectional view schematically illustrating an example of a waterproofing member according to a second embodiment of the present invention. FIG. 12 is a cross-sectional view showing the structure of the waterproofing member used in the examples and comparative examples. FIG. 13 is a schematic diagram for explaining a method for evaluating the insertion loss of a waterproofing member. FIG. 14A is a diagram (10,000x magnification) showing the results of observing the first main surface of the waterproof film of the waterproof member of Example 2 with a scanning electron microscope (SEM). FIG. 14B is a diagram (1000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 2. FIG. 15A is a diagram (10,000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 3. FIG. 15B is a diagram (1000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 3. FIG. 16A is a diagram (10,000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 4. FIG. 16B is a diagram (1000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 4. FIG. 17A is a diagram (10,000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 5. FIG. 17B is a diagram (1000x magnification) showing the results of SEM observation of the first main surface of the waterproof film provided in the waterproof member of Example 5.

The waterproof member according to the first aspect of the present invention comprises:
A waterproofing member that is disposed to close an opening of an object having an opening surface on which an opening is formed,
a waterproof membrane having a first main surface facing the opening when the waterproof membrane is disposed to close the opening and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
The first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more.

In a second aspect of the present invention, for example, in the waterproof member according to the first aspect, the object includes a microelectromechanical system (MEMS).

In a third aspect of the present invention, for example, in a waterproof member according to the first or second aspect, the average particle size of the particles in the region of the first main surface is in the range of 0.2 μm to 5 μm.

In a fourth aspect of the present invention, for example, in a waterproof member according to any one of the first to third aspects, the waterproof film further includes a coating layer that covers at least a portion of the surface of the particles.

In a fifth aspect of the present invention, for example, in a waterproof member according to any one of the first to fourth aspects, the arithmetic mean height of the region on the first principal surface is less than 1 μm.

In a sixth aspect of the present invention, for example, in a waterproof member according to any one of the first to fifth aspects, the difference in insertion loss for a sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied to the second main surface of the waterproof membrane for 10 minutes is 2.5 dB or less.

In a seventh aspect of the present invention, for example, in a waterproof member according to any one of the first to sixth aspects, the main body of the waterproof membrane is a non-porous membrane.

In an eighth aspect of the present invention, for example, in a waterproof member according to any one of the first to seventh aspects, the main body of the waterproof membrane includes at least one material selected from the group consisting of silicone rubber, polyurethane, polyethylene terephthalate, polyimide, and polytetrafluoroethylene.

In a ninth aspect of the present invention, for example, in a waterproof member according to any one of the first to eighth aspects, the main body portion of the waterproof membrane includes an elastomer.

In a tenth aspect of the present invention, for example, in a waterproof member according to any one of the first to ninth aspects, when the waterproof member is positioned so as to close the opening, the first main surface of the waterproof membrane and the opening surface face each other via a space that contacts the first main surface and the opening surface.

In an eleventh aspect of the present invention, for example, the waterproofing member according to any one of the first to tenth aspects further comprises an adhesive layer bonded to the first main surface of the waterproof membrane.

In a twelfth aspect of the present invention, for example, the waterproof member according to any one of the first to eleventh aspects further comprises a support layer that is spaced apart from the waterproof membrane and has breathability in the thickness direction, and the support layer is positioned between the waterproof membrane and the object when the waterproof member is positioned to block the opening.

In a thirteenth aspect of the present invention, for example, in the waterproofing member according to the twelfth aspect, the support layer has a first main surface facing the opening and a second main surface opposite the first main surface when the waterproofing member is positioned to close the opening, and the waterproofing member further includes a bonding layer bonding the first main surface of the waterproof membrane to the second main surface of the support layer, and a pressure-sensitive adhesive layer bonded to the first main surface of the support layer.

A waterproof member according to a fourteenth aspect of the present invention comprises:
A waterproof member disposed inside a microelectromechanical system (MEMS) including a substrate having an opening functioning as a sound vent, a MEMS die having a vibration plate, and a cap covering the MEMS die, the waterproof member comprising:
a waterproof membrane having a first main surface facing the diaphragm when the waterproof membrane is disposed so as to close the opening and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
The first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more.

A waterproof member according to a fifteenth aspect of the present invention comprises:
A waterproofing member that is disposed so as to close an opening of an object having an opening surface on which an opening is formed,
a waterproof membrane having a first main surface and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
The first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more,
When the waterproof membrane is disposed so as to cover the opening, the first main surface or the second main surface of the waterproof membrane faces the opening.

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments.

(First embodiment)
An example of a waterproof member according to a first embodiment is shown in FIGS. 1 and 2. The waterproof member 10 shown in FIGS. 1 and 2 includes a waterproof membrane 1. As shown in FIG. 3, the waterproof member 10 is used by being disposed so as to cover an opening 51 of an object 50 having an opening surface 51s on which the opening 51 is formed. In this specification, the term "opening surface" refers to a surface on which an opening is formed, i.e., a surface having an opening. The object 50 includes, for example, products such as acoustic equipment and microelectromechanical systems (MEMS). The object 50 may also be a MEMS.

The waterproof membrane 1 is a membrane that prevents water from entering while allowing sound to pass through. The waterproof membrane 1 has a shape that blocks the opening 51. The waterproof membrane 1 has a first main surface 1a and a second main surface 1b opposite the first main surface 1a. As shown in Figure 3, in the first embodiment, when the waterproof membrane 1 is positioned to block the opening 51, the first main surface 1a of the waterproof membrane 1 faces the opening 51. In this specification, "facing the opening" means facing the opening side, and is not limited to cases where two components face each other, but also includes cases where another component exists between the two components. In this specification, "main surface" means the surface of the sheet-like member that has the largest area.

As shown in Figure 3, when the waterproof member 10 is positioned to cover the opening 51, the first main surface 1a of the waterproof membrane 1 and the opening surface 51s face each other via a space that contacts the first main surface 1a and the opening surface 51s.

As shown in Figures 1 and 2, the waterproofing member 10 further includes an adhesive layer 2 bonded to the first main surface 1a of the waterproofing membrane 1. In this embodiment, the adhesive layer 2 is disposed on the periphery of the first main surface 1a of the waterproofing membrane 1. Note that the reference numeral 4 in Figure 2 indicates an area through which sound passes when the waterproofing member 10 is installed in a device, i.e., a sound-transmitting area (sound-passing area).

As shown in Figure 1, the first main surface 1a of the waterproof membrane 1 has an exposed area where the adhesive layer 2 is not present. Hereinafter, the exposed area will be referred to as the exposed area 10a. As shown in Figure 3, when the waterproof member 10 is positioned to cover the opening 51, it has an overlapping area 10b where the exposed area 10a and the opening surface 51s overlap when viewed from a direction perpendicular to the main surface of the waterproof membrane 1.

FIG. 4A is a cross-sectional view schematically illustrating an example of a waterproof membrane 1 included in a waterproof member 10. As shown in FIG. 4A, in this embodiment, the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11. As shown in FIG. 1, the first main surface 1a of the waterproof membrane 1 has a region R1a in which the arithmetic mean height Sa is 0.20 μm or greater. Region R1a corresponds to, for example, exposed region 10a.

In this specification, the term "particle" refers not only to a single particle but also to an aggregate of multiple particles. Therefore, when "particle" in this specification refers to an aggregate of multiple particles, the term "particle" can be replaced with "powder."

When pressure such as water pressure is applied from the second main surface 1b of the waterproof membrane 1 to the waterproof member 10 placed on the object 50, the waterproof membrane 1 deforms so as to be distorted toward the opening surface 51s. This phenomenon will be explained with reference to Figure 5. Figure 5 is a schematic cross-sectional view illustrating the deformation of the waterproof membrane 1 when water pressure p is applied to the waterproof member 10 in the state shown in Figure 3. As shown in Figure 5, when water pressure p is applied to the waterproof member 10 from the outside (second main surface 1b) of the object 50 (Figure 5(A)), the waterproof membrane 1 deforms so as to be pressed against the opening surface 51s (Figure 5(B)). In conventional waterproof members, the deformation of the waterproof membrane sometimes persists without recovering even after the water pressure p is released. This continued deformation of the waterproof membrane reduces the sound transmission characteristics of the waterproof member.

The inventors therefore conducted extensive research into ways to prevent a decline in the sound transmission characteristics of waterproofing members. As a result, they came up with the idea of focusing on the structure of the first main surface of the waterproof membrane (the main surface facing the opening).

In a waterproof member 10 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first principal surface 1a than the main body 11, and the first principal surface 1a of the waterproof membrane 1 has a region R1a where the arithmetic mean height Sa is 0.20 μm or greater, the contact area between the first principal surface 1a and the opening surface 51s can be reduced when the waterproof membrane 1 is deformed by being pressed against the opening surface 51s due to the application of pressure such as water pressure (see Figure 5 (B)). As a result, after the pressure is released, the first principal surface 1a of the waterproof membrane 1 easily separates from the opening surface 51s and returns to its original shape. In other words, the deformation of the waterproof membrane 1 is easily recovered. Therefore, the waterproof member 10 of this embodiment is suitable for suppressing a decrease in sound transmission characteristics.

One surface of the main body 11 located on the first principal surface 1a side of the waterproof membrane 1 is defined as the first surface 11a of the main body 11, and the other surface of the main body 11 located on the first principal surface 1b side of the waterproof membrane 2 is defined as the second surface 11b of the main body 11. In this case, as shown in Figure 4A, particles 12 may be present attached to the first surface 11a of the main body 11. All of the particles 12 may be attached to the first surface 11a of the main body 11.

In the waterproof member 10 shown in Figure 1, region R1a corresponds to the entire first principal surface 1a. In other words, the entire first principal surface 1a of the waterproof membrane 1 satisfies the requirement that the arithmetic mean height Sa be 0.20 μm or greater. With this configuration, the above-described effects of the waterproof member 10 of this embodiment are more easily achieved.

However, the position of region R1a is not limited to the example shown in Figure 1. Figure 6 is a cross-sectional view schematically showing another example of the waterproof membrane 1 provided in the waterproof member 10. In the waterproof member 10A shown in Figure 6, region R1a corresponds to the exposed region 10a. That is, the arithmetic mean height Sa in the exposed region 10a is 0.20 µm or more. As shown in Figure 6, region R1a may correspond to the exposed region 10a. Even with this configuration, the above-described effects of the waterproof member 10 of this embodiment can be obtained.

Although not shown in the figures, region R1a may correspond to overlap region 10b (see Figure 3). That is, the arithmetic mean height Sa in overlap region 10b may be 0.20 μm or greater. Even with such a configuration, the above-described effects of the waterproofing member 10 of this embodiment can be obtained.

The lower limit of the arithmetic mean height Sa of the region R1a of the first principal surface 1a may be 0.25 μm.

The arithmetic mean height Sa of region R1a of the first principal surface 1a may be less than 1 μm. If the arithmetic mean height Sa of region R1a is less than 1 μm, the bond between the first principal surface 1a of the waterproof membrane 1 and the adhesive layer 2 is less likely to be hindered, even if, for example, region R1a corresponds to the entire first principal surface 1a.

The upper limit of the arithmetic mean height Sa of the region R1a of the first principal surface 1a may be 0.90 μm, 0.80 μm, 0.70 μm, or even 0.65 μm.

(Method for measuring the arithmetic mean height Sa of the waterproof membrane)
The arithmetic mean height Sa of the region R1a of the first main surface 1a of the waterproof membrane 1 can be measured in accordance with the non-contact (optical probe) evaluation method of ISO 25178. Specifically, the arithmetic mean height Sa of the region R1a of the first main surface 1a can be measured using a shape analysis laser microscope (for example, VK X260 manufactured by Keyence Corporation) at an observation magnification of 160x. The arithmetic mean height Sa of the second main surface 1b of the waterproof membrane 1 can also be measured in a similar manner.

For example, the waterproof member 10 has a difference in insertion loss IL _D of 2.5 dB or less for a sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied for 10 minutes to the second main surface 1 b of the waterproof membrane 1. A difference in insertion loss IL _D of 2.5 dB or less for a sound with a frequency of 1 kHz means that the difference in insertion loss IL _D at a frequency of 1 kHz does not exceed 2.5 dB.

In a waterproof member 10 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof membrane 1 has a region R1a in which the arithmetic mean height Sa is 0.20 μm or more, the insertion loss difference IL _D is kept low to 2.5 dB or less. In other words, deterioration of sound transmission characteristics is suppressed. The lower limit of the insertion loss difference IL _D of the waterproof member 10 is not particularly limited. The lower limit of the insertion loss difference IL _D is, for example, 0 dB.

(Method for measuring the insertion loss of a waterproof member)
The method for measuring the insertion loss of the waterproofing member 10 for a sound with a frequency of 1 kHz will be described in detail in the section of Examples.

The thickness of the waterproof membrane 1 is, for example, 1 μm or more and 100 μm or less. When the thickness of the waterproof membrane 1 is within this range, it is possible to improve the sound transmission characteristics while ensuring sufficient waterproofness and strength. Generally, the thinner the waterproof membrane 1, the more likely it is to deform. As mentioned above, the sound transmission characteristics of the waterproof member 10 may deteriorate due to deformation of the waterproof membrane 1. However, in the waterproof member 10 of this embodiment, the waterproof membrane 1 easily recovers from deformation, so the deterioration of sound transmission characteristics due to continued deformation is suppressed. Therefore, by making the thickness of the waterproof membrane 1 relatively small, at 100 μm or less, it is possible to improve the sound transmission characteristics.

The upper limit of the thickness of the waterproof membrane 1 may be 90 μm, 80 μm, 70 μm, or even 60 μm. The lower limit of the thickness of the waterproof membrane 1 may be 3 μm or 5 μm.

(Method for measuring waterproof membrane thickness)
The thickness of the waterproof membrane 1 can be determined by measuring the thickness at any five points on the waterproof membrane 1 using, for example, a dial gauge, and averaging these measurements. The thickness of the waterproof membrane 1 can also be determined by measuring the thickness at any five points on a scanning electron microscope (SEM) image of a cross section of the waterproof membrane 1 and averaging these measurements. The thicknesses of other components can be determined in a similar manner.

The average particle size of the particles 12 in region R1a of the first principal surface 1a is preferably in the range of 0.2 μm to 5 μm. This numerical range can be achieved, for example, by arranging particles 12 with an average particle size in the range of 0.2 μm to 5 μm closer to the first principal surface 1a than the main body 11. Particles 12 with an average particle size in the range of 0.2 μm to 5 μm have high dispersibility. This allows the particles 12 to be more uniformly arranged closer to the first principal surface 1a than the main body 11. Therefore, in a waterproof membrane 1 where the average particle size of the particles 12 in region R1a is in the range of 0.2 μm to 5 μm, the particles 12 are more uniformly present in region R1a, which makes it easier to reduce the contact area between the first principal surface 1a and the opening surface 51s when the waterproof membrane 1 is deformed by being pressed against the opening surface 51s due to the application of pressure such as water pressure.

The lower limit of the average particle size of the particles 12 in region R1a of the first principal surface 1a may be 0.3 μm, 0.4 μm, or even 0.5 μm. The upper limit of the average particle size of the particles 12 in region R1a may be 4.5 μm, 4.0 μm, 3.5 μm, 3.0 μm, 2.5 μm, or even 2.0 μm.

(Method for measuring average particle size)
The average particle size of the particles 12 in the region R1a of the first main surface 1a of the waterproof membrane 1 can be determined from a surface SEM image obtained by observing the region R1a of the first main surface 1a of the waterproof membrane 1 with an SEM. In the surface SEM image, the equivalent diameter of any number of particles 12 (at least 50 particles) is measured. The average value of the equivalent diameters can be considered to be the average particle size of the particles 12. The equivalent diameter means the diameter of a circle having the same area. The average particle size of the particles 12 as raw material powder is the particle size (D50) corresponding to 50% of the cumulative volume from the smaller particle size side in the particle size distribution of the particles 12 measured based on a laser diffraction/scattering method.

The raw material of particles 12 is not particularly limited. Examples of raw materials for particles 12 include silicone rubber; silicone resin; silica; and metal oxides such as aluminum oxide, zirconium oxide, and titanium oxide. One or a combination of two or more selected from these may be used as raw materials for particles 12.

Particle 12 may have a coating layer that covers at least a portion of its surface. That is, particle 12 may be a composite in which at least a portion of its surface is covered with a coating layer. The material of the coating layer is not particularly limited. The materials listed as the materials for particle 12 can be used as the material for the coating layer. The coating layer may contain, for example, a silicone resin.

Particles 12 may contain at least one material selected from the group consisting of silicone rubber, silicone resin, and silica. Particles 12 may contain at least one material selected from the group consisting of silicone rubber, silicone resin, and silica as a main component. Waterproof membrane 1 may consist of only at least one material selected from the group consisting of silicone rubber, silicone resin, and silica. In this specification, "main component" means the component that is contained in the largest amount by mass. The same applies to other raw materials.

Particles 12 may be a composite in which at least a portion of the surface of a silicone rubber particle is coated with a silicone resin. Particles 12 may be silicone resin particles or silica particles.

The shape of the particles 12 is not particularly limited, as long as it is possible to achieve an arithmetic mean height Sa of 0.20 μm or greater in the region R1a of the first principal surface 1a. Examples of the shape of the particles 12 include spherical, plate-like, and needle-like shapes. The particles 12 may also be spherical. If the particles 12 are spherical, the contact area between the first principal surface 1a and the opening surface 51s can be further reduced when the waterproof membrane 1 is deformed by being pressed against the opening surface 51s due to the application of pressure such as water pressure. This makes it easier for the waterproof membrane 1 to recover from deformation.

As shown in FIG. 4A, the waterproof membrane 1 may further include a coating layer 13 that covers at least a portion of the surface 12s of the particle 12. That is, the waterproof membrane 1 may include a main body 11, particles 12, and a coating layer 13. The coating layer 13 contributes to improving the adhesion between the first surface 11a of the main body 11 and the particles 12. Therefore, for example, the particles 12 are prevented from falling off from the first surface 11a of the main body 11. The coating layer 13 may cover the entire surface 12s of the particle 12.

The coating layer 13 may further cover at least a portion of the first surface 11a of the main body portion 11. The coating layer 13 may further cover the entire first surface 11a of the main body portion 11.

As shown in FIG. 4A, the coating layer 13 may cover the entire first surface 11a of the main body portion 11, and the particles 12 may be included in the coating layer 13. However, the form of the coating layer 13 is not limited to the example shown in FIG. 4A. For example, some of the multiple particles 12 located closer to the first main surface 1a than the main body portion 11 may be included in the coating layer 13. In other words, the multiple particles 12 located closer to the first main surface 1a than the main body portion 11 may include particles 12 protruding from the coating layer 13.

Figure 4B is an enlarged view of portion IVB in Figure 4A. In the cross section of the waterproof membrane 1, the height of the particles 12 is defined as height H12, and the thickness of the coating layer 13 in the area where the particles 12 are not present is defined as thickness T13. In this case, the ratio of thickness T13 to height H12 (T13/H12) is preferably 0.05 to 0.8. When the ratio (T13/H12) is within the above numerical range, for example, it is easy to achieve an arithmetic mean height Sa of region R1a of the first principal surface 1a of 0.20 μm or more while suppressing the particles 12 from falling off from the first surface 11a of the main body portion 11. In this specification, the height H12 of the particles 12 refers to the vertical distance from the first surface 11a of the main body portion 11 to the highest point on the surface 12s of the particles 12 in the cross section of the waterproof membrane 1. However, as shown in Figure 4B, when the coating layer 13 covers the surface 12s of the particle 12, the height H12 of the particle 12 means the vertical distance from the first surface 11a of the main body 11 to the highest point on the first principal surface 1a. The thickness T13 of the coating layer 13 in the area where no particles 12 are present means the vertical distance from the first surface 11a of the main body 11 to the highest point on the first principal surface 1a in the cross section of the waterproof membrane 1.

The lower limit of the ratio (T13/H12) may be 0.07 or 0.1. The upper limit of the ratio (T13/H12) may be 0.7, 0.6, or even 0.5.

The height H12 of the particles 12 and the thickness T13 of the coating layer 13 can be determined from a cross-sectional SEM image obtained by observing the cross section of the waterproof membrane 1 with an SEM. In the cross-sectional SEM image, the heights of any number of particles 12 (at least 50) are measured. The average of the measured heights can be considered to be the height H12 of the particles 12. However, the height of the particles 12 refers to the height in a cross section passing through the center of gravity of the particles 12. Similarly, in the cross-sectional SEM image, the thickness of the coating layer 13 is measured at any locations (at least 50 locations) where no particles 12 are present. The average of the measured thicknesses can be considered to be the thickness T13 of the coating layer 13.

The height H12 of the particles 12 is preferably in the range of 0.2 μm to 5 μm. The lower limit of the height H12 of the particles 12 may be 0.3 μm, 0.4 μm, or even 0.5 μm. The upper limit of the height H12 of the particles 12 may be 4.5 μm, 4.0 μm, 3.5 μm, 3.0 μm, 2.5 μm, or even 2.0 μm.

The thickness T13 of the coating layer 13 in the portion where particles 12 are not present is preferably in the range of 0.01 μm to 4 μm. The lower limit of the thickness T13 of the coating layer 13 may be 0.014 μm or 0.020 μm. The upper limit of the thickness T13 of the coating layer 13 may be 3.5 μm, 3.0 μm, or even 2.5 μm.

For example, resin can be used as the raw material for the coating layer 13. Examples of resins include crosslinked silicone oligomer, polyurethane, polyester, polymethyl methacrylate, ethylene vinyl acetate copolymer, and epoxy resin. It is preferable that the coating layer 13 contains resin as its main component.

In this embodiment, the main body 11 of the waterproof membrane 1 is a non-porous membrane. Therefore, the waterproof member 10 is particularly suitable for improving waterproofing. In this embodiment, "non-porous" means that there are no pores connecting one main surface of the membrane to the other, or that the number of pores is extremely small. For example, a membrane with an air permeability expressed as a Gurley number of greater than 10,000 seconds/100 mL can be determined to be a non-porous membrane. Here, the Gurley number is a value obtained by measurement in accordance with JIS P8117:2009.

The material of the main body 11 of the waterproof membrane 1 is not particularly limited. Examples of materials that can be used to make the main body 11 include silicone rubber, polyurethane, polyethylene terephthalate, polyimide, and polytetrafluoroethylene. The waterproof membrane 1 may contain at least one material selected from the group consisting of silicone rubber, polyurethane, polyethylene terephthalate, polyimide, and polytetrafluoroethylene.

The main body 11 of the waterproof membrane 1 may contain an elastomer. The main body 11 may contain an elastomer as a main component. The main body 11 may consist solely of an elastomer.

The elastomer used in the main body 11 of the waterproof membrane 1 is a rubber-like elastic material. The elastomer is preferably a rubber-like elastic material with rubber hardness. The elastomer may be a thermosetting elastomer or a thermoplastic elastomer. There are no particular limitations on the elastomer. Examples of elastomers include silicone rubber, urethane rubber, ethylene propylene diene rubber (EPDM), acrylic rubber, and natural rubber. One or a combination of two or more elastomers selected from these can be used. Of these, silicone rubber and urethane rubber are preferably used. The elastomer may contain at least one selected from the group consisting of silicone rubber and urethane rubber.

The elastomer used in the main body 11 of the waterproof membrane 1 may be silicone rubber.

The main body 11 of the waterproof membrane 1 may contain urethane rubber. The main body 11 may contain urethane rubber as a main component. The main body 11 may consist solely of urethane rubber.

The main body 11 of the waterproof membrane 1 may contain polytetrafluoroethylene. The main body 11 may contain polytetrafluoroethylene as a main component. The main body 11 may consist solely of polytetrafluoroethylene.

The main body 11 of the waterproof membrane 1 may be colored. If the main body 11 is transparent or white, the waterproof membrane 1 may be noticeable when the waterproof member 10 is placed so as to block an opening in the housing of an apparatus. Therefore, by coloring the main body 11 to match the color of the housing in which it is placed, it is possible to achieve a waterproof member 10 that is less noticeable when placed in the housing. The main body 11 may be colored black, for example. Furthermore, when the design of the housing is important, placing the waterproof member 10 so as to block an opening in the housing may detract from the design. Therefore, by coloring the main body 11 to match the design of the housing, it is possible to maintain the design.

The coloring of the main body 11 of the waterproof membrane 1 can be achieved, for example, by incorporating a colorant into the raw material of the main body 11. When creating a stylish device, it is desirable that the colorant used has the ability to absorb at least part of the light in the wavelength range of 380 nm or more and 500 nm or less. In other words, it is desirable that the main body 11 be colored black, gray, brown, green, yellow, or pink with this colorant. For example, methods of coloring the main body 11 include mixing a colorant such as pigment or carbon black into the raw material before it is made into a sheet, and coloring the raw material after it has been made into a sheet with a colorant using dyeing or printing techniques. Note that using carbon black as a colorant can improve the strength of the waterproof membrane 1, and also has the effect of further improving its waterproofness.

The waterproof membrane 1 does not have to contain organic fluorine compounds (PFAS). In other words, the waterproof membrane 1 may be a membrane that does not contain organic fluorine compounds.

In the example shown in Figures 1 and 2, the adhesive layer 2 is annular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the adhesive layer 2 is not limited to the example shown in Figures 1 and 2.

In this specification, "adhesive" means "sticking" or "adhesion." For example, "adhesive layer" means "adhesive layer" or "adhesive layer."

In this specification, "pressure-sensitive adhesive," as defined by JIS, refers to a type of adhesion that is temporary and can bond with just the application of slight pressure. It also refers to a material that has cohesive strength and elasticity, which allows it to adhere strongly but also peel away from hard, smooth surfaces. Pressure-sensitive adhesives are soft solids that do not change state like glue. Because pressure-sensitive adhesives wet to the adherend in their original state and resist peeling, they instantly demonstrate practical adhesive strength when two adherends are bonded together. In other words, pressure-sensitive adhesives possess both the fluidity of a liquid that allows them to wet to the adherend, and the cohesive strength of a solid that resists peeling. Because pressure-sensitive adhesives are soft solids, the contact area with the adherend gradually increases as pressure is applied or over time. Furthermore, because they can maintain this softness for long periods of time, they have the property of being removable when desired.

In this specification, "adhesive" refers to the property of bonding solid surfaces of the same or different types together to form a single unit, as defined by JIS. An adhesive is a fluid substance that wets and blends with the adherends when bonding them together. It then transforms into a solid through heating or chemical reaction, firmly bonding the adherends at their interfaces and exerting resistance to peeling. In other words, an adhesive wets as a fluid substance and bonds as a solid.

The material of the adhesive layer 2 can be selected as appropriate so that it can be attached and fixed directly to the acoustic component to which the waterproofing member 10 is applied, or so that it can be attached and fixed to the housing that houses the acoustic component. For example, a general-purpose double-sided tape with a substrate, a double-sided tape without a substrate (i.e., a tape with only an adhesive), etc. can be used as appropriate for the adhesive layer 2, taking into consideration the adhesiveness to the waterproof membrane 1 and the adhesiveness to the housing or case.

In the example shown in Figures 1 and 2, the waterproofing member 10 is circular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the waterproofing member 10 is not limited to the example shown in Figures 1 and 2. The shape of the waterproofing member 10 may be a circle (including an approximate circle), an ellipse (including an approximate ellipse), or a polygon, including a rectangle and a square. The corners of the polygon may be rounded.

The thickness of the waterproof member 10 is, for example, 2000 μm or less. In this specification, the thickness of the waterproof member 10 refers to the thickness of the waterproof member 10 other than the exposed region 10a. The thickness of the waterproof member 10 may be 1000 μm or less, 750 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or even 300 μm or less. The lower limit of the thickness of the waterproof member 10 is, for example, 15 μm.

In the waterproof member 10, the second main surface 1b of the waterproof membrane 1 may have the same structure as the first main surface 1a. That is, the waterproof membrane 1 may include particles 12 located closer to the second main surface 1b than the main body 11, and the second main surface 1b of the waterproof membrane 1 may have a region where the arithmetic mean height Sa is 0.20 μm or more. The entire second main surface 1b of the waterproof membrane 1 may satisfy the requirement of an arithmetic mean height Sa of 0.20 μm or more. If the second main surface 1b of the waterproof membrane 1 has the same structure as the first main surface 1a, the above-mentioned effects can be obtained regardless of which side of the waterproof membrane 1 faces the opening 51 of the object 50, so there is no need to be careful about mixing up the main surfaces, improving handleability.

[Method of manufacturing waterproof member]
The waterproof member 10 described above can be manufactured, for example, by the following method. The manufacturing method will be described below using the waterproof member 10 shown in FIG.

First, the main body 11 of the waterproof membrane 1 is prepared. There are no particular limitations on the method for preparing the main body 11, and it can be selected appropriately depending on the purpose. For example, a method can be used in which the raw material solution for the main body 11 is extruded into a thin layer onto a releasable substrate using a discharge means such as a die, or a method can be used in which the raw material solution for the main body 11 is poured onto a releasable substrate and then a thin film is formed using an applicator, wire bar, or knife coater. Furthermore, the main body 11 can be adjusted to a predetermined thickness using a cutting method. In this way, a sheet-like main body 11 is obtained.

Next, particles 12 are arranged on one surface (first surface 11a) of the main body 11. The method for arranging the particles 12 is not particularly limited. For example, a solution containing particles 12 and the raw materials of the coating layer 13 may be applied to one surface of the main body 11, dried at room temperature, and then heated to arrange the particles 12 on one surface of the waterproof membrane 1. In this way, a waterproof membrane 1 can be obtained that includes the main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and in which the first main surface 1a of the waterproof membrane 1 has a region R1a with an arithmetic mean height Sa of 0.20 μm or more.

Next, an adhesive sheet (e.g., double-sided tape) is prepared for forming the adhesive layer 2. Holes corresponding to the sound-transmitting areas 4 are pre-formed in the adhesive sheet. This adhesive sheet is attached to the first main surface 1a of the waterproof membrane 1, and then punched into a predetermined shape to obtain the waterproof member 10.

An example of a waterproof member according to the first embodiment has been described above using Figures 1 to 6, but the waterproof member according to the first embodiment is not limited to the example described above. Below, another example of a waterproof member according to this embodiment will be described using Figures 7 to 10. Note that in the modified examples described below, elements common to the waterproof member 10 described above will be designated by the same reference numerals, and descriptions thereof may be omitted.

(Modification)
Another example of the waterproof member according to this embodiment is shown in Figures 7 to 10. The waterproof member 20 shown in Figures 7 to 10 further includes a support layer 3 that is arranged apart from the waterproof membrane 1 and has breathability in the thickness direction.

Figure 9 is a cross-sectional view showing an example of a state in which the waterproofing member 20 is positioned to block the opening 51 of the object 50. As shown in Figure 9, when the waterproofing member 20 is positioned to block the opening 51, the support layer 3 is located between the waterproof membrane 1 and the object 50.

The support layer 3 is attached to limit deformation of the waterproof membrane 1 to a certain range. When the waterproofing member 20 is positioned to block the opening 51, the support layer 3 has a first main surface 3a that faces the opening 51, and a second main surface 3b that faces the first main surface 1a of the waterproof membrane 1. As shown in Figure 9, when the waterproofing member 20 is positioned to block the opening 51, the first main surface 1a of the waterproof membrane 1 and the second main surface 3b of the support layer 3 face each other via a space that contacts the first main surface 1a and second main surface 3b.

10 is a schematic cross-sectional view illustrating the deformation of the waterproof membrane 1 when water pressure p is applied to the waterproof member 20 in the state shown in FIG. 9. As shown in FIG. 10, when water pressure p is applied to the waterproof member 20 from the outside of the object 50 (the second main surface 1b side of the waterproof membrane 1) (FIG. 10A), the waterproof membrane 1 deforms so as to be pressed against the second main surface 3b of the support layer 3 (FIG. 10B). According to a waterproof member 20 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof membrane 1 has a region R1a having an arithmetic mean height Sa of 0.20 μm or more, when the waterproof membrane 1 is deformed so as to be pressed against the second main surface 3b of the support layer 3 by the application of pressure such as water pressure, the contact area between the first main surface 1a of the waterproof membrane 1 and the second main surface 3b of the support layer 3 can be reduced (see FIG. 10B). As a result, after the pressure is released, the first main surface 1a of the waterproof membrane 1 easily separates from the second main surface 3b of the support layer 3 and returns to its original shape. In other words, the waterproof membrane 1 is easily restored to its original shape after deformation. Therefore, the waterproof member 20 is suitable for preventing a decrease in sound transmission characteristics.

As shown in Figures 7 and 8, the waterproofing member 20 includes an adhesive layer 22 bonded to the first main surface 3a of the support layer 3. The adhesive layer 22 corresponds to the adhesive layer 2 in the waterproofing member 10. The adhesive layer 22 is disposed on the periphery of the first main surface 3a of the support layer 3. Note that the reference numeral 4 in Figure 8 indicates the area through which sound passes when the waterproofing member 20 is installed in a device, i.e., the sound-transmitting area (sound-passing area).

As shown in Figures 7 and 8, the waterproofing member 20 includes a bonding layer 21 that bonds the first main surface 1a of the waterproof membrane 1 to the second main surface 3b of the support layer 3. The bonding layer 21 is disposed on the peripheral edge of the first main surface 1a of the waterproof membrane 1 and the peripheral edge of the second main surface 3b of the support layer 3.

As shown in Figure 7, the first principal surface 1a of the waterproof membrane 1 has an exposed area (exposed area 10a) where the bonding layer 21 is not present. The second principal surface 3b of the support layer 3 has an exposed area (exposed area 30a) where the bonding layer 21 is not present.

In the waterproof member 20 shown in Figure 7, region R1a corresponds to the entire first principal surface 1a. In other words, the entire first principal surface 1a of the waterproof membrane 1 satisfies the requirement that the arithmetic mean height Sa be 0.20 μm or greater. With this configuration, the above-described effects of the waterproof member 20 of this embodiment are more easily achieved.

However, the position of region R1a is not limited to the example shown in Figure 7. Region R1a may correspond to exposed region 10a. In other words, the arithmetic mean height Sa in exposed region 10a may be 0.20 μm or greater. Even with such a configuration, the above-described effects of the waterproofing member 20 of this embodiment can be obtained.

Region R1a may correspond to overlap region 10b (see Figure 3). That is, the arithmetic mean height Sa in overlap region 10b may be 0.20 μm or greater. Even with this configuration, the above-described effects of the waterproofing member 20 of this embodiment can be obtained.

As shown in Figure 7, the waterproof member 20 has a bonding region J1 where the waterproof membrane 1 and the support layer 3 are bonded, and a non-bonded region J2 surrounded by the bonding region J1 when viewed from a direction perpendicular to the main surface of the waterproof member 20. The bonding region J1 includes the peripheral regions of the waterproof membrane 1 and the support layer 3. The waterproof membrane 1 and the support layer 3 are bonded by a bonding layer 21.

As shown in Figure 7, in the non-bonded region J2, the waterproof membrane 1 and the support layer 3 are spaced apart from each other. In other words, in the non-bonded region J2, the support layer 3 is positioned at a distance from the waterproof membrane 1.

For example, the waterproof member 20 has a difference in insertion loss IL _D of 2.5 dB or less for a sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied for 10 minutes to the second main surface 1 b of the waterproof membrane 1. A difference in insertion loss IL _D of 2.5 dB or less for a sound with a frequency of 1 kHz means that the difference in insertion loss IL _D at a frequency of 1 kHz does not exceed 2.5 dB.

In a waterproof member 20 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof membrane 1 has a region R1a in which the arithmetic mean height Sa is 0.20 μm or more, the insertion loss difference IL _D is kept low to 2.5 dB or less. In other words, deterioration of sound transmission characteristics is suppressed. The lower limit of the insertion loss difference IL _D of the waterproof member 20 is not particularly limited. The lower limit of the insertion loss difference IL _D is, for example, 0 dB.

The thickness of the support layer 3 in the non-bonded region J2 is, for example, 500 μm or less. This allows the waterproof member 20 to ensure good sound transmission characteristics while including the support layer 3. The thickness of the support layer 3 may be 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, or even 100 μm or less. The lower limit of the thickness of the support layer 3 in the non-bonded region J2 is, for example, 30 μm or 50 μm. The support layer 3 may have the above thickness without being limited to the non-bonded region J2. The entire support layer 3 may have the above thickness.

The distance between the waterproof membrane 1 and the support layer 3 in the non-bonded region J2 is, for example, 150 μm or less. A distance of 150 μm or less ensures good sound transmission characteristics even when the support layer 3 is provided. The distance may be 125 μm or less, 100 μm or less, 75 μm or less, or even 50 μm or less. The lower limit of the distance is, for example, 5 μm, and may also be 10 μm, 20 μm, or even 30 μm.

The in-plane air resistance of the support layer 3 may be 100,000 seconds/100 mL or more, 150,000 seconds/100 mL or more, 200,000 seconds/100 mL or more, 250,000 seconds/100 mL or more, 300,000 seconds/100 mL or more, or even exceed 300,000 seconds/100 mL. The upper limit of the in-plane air resistance of the support layer 3 is, for example, 1,000,000 seconds/100 mL or less. The in-plane air resistance of the support layer 3 can be evaluated as the air resistance between the portion of the non-bonded region J2 on the main surface of the support layer 3 when incorporated into the waterproof member 20 and the outer peripheral side surface 3s of the support layer 3. Here, air resistance is the time required for 100 mL of air to pass through the member in the in-plane direction.

In the example shown in Figures 7 and 8, the waterproofing member 20 and the non-bonding region J2 are both circular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shapes of the waterproofing member 20 and the non-bonding region J2 are not limited to the examples shown in Figures 7 and 8. The shapes of the waterproofing member 20 and the non-bonding region J2 may be, independently of each other, a circle (including an approximate circle), an ellipse (including an approximate ellipse), or a polygon including a rectangle and a square. The corners of the polygon may be rounded.

The shape of the bonded region J1 is not limited as long as it surrounds the non-bonded region J2. The bonded region J1 is typically a region that includes the peripheral edges of the waterproof membrane 1 and/or the support layer 3. In the example shown in Figures 7 to 8, the region other than the bonded region J1 where the waterproof membrane 1 and the support layer 3 are bonded is the non-bonded region J2. In the example shown in Figures 7 to 8, the waterproof membrane 1 is exposed on one side of the waterproof member 20 (the side that faces the outside when placed on the object 50) in the non-bonded region J2. Furthermore, the support layer 3 is exposed on the other side of the waterproof member 20 (the side that faces the opening 51 when placed on the object 50) in the non-bonded region J2. In other words, the non-bonded region J2 corresponds to the exposed region 10a and the exposed region 30a.

The shape of the waterproof membrane 1 and the shape of the support layer 3 may be the same or different when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. In the example shown in Figures 7 and 8, the shape of the waterproof membrane 1 and the shape of the support layer 3 are the same as each other and the same as the shape of the waterproof member 20.

The thickness of the waterproof member 20 is, for example, 2000 μm or less. Note that in this specification, the thickness of the waterproof member 20 refers to the thickness of the waterproof member 20 in the bonding region J1. The thickness of the waterproof member 20 may be 1000 μm or less, 750 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, or even 300 μm or less. The lower limit of the thickness of the waterproof member 20 is, for example, 50 μm.

In the waterproof member 20, the second main surface 1b of the waterproof membrane 1 may have the same structure as the first main surface 1a. That is, the waterproof membrane 1 may include particles 12 located closer to the second main surface 1b than the main body 11, and the second main surface 1b of the waterproof membrane 1 may have a region where the arithmetic mean height Sa is 0.20 μm or more. The entire second main surface 1b of the waterproof membrane 1 may satisfy the requirement of an arithmetic mean height Sa of 0.20 μm or more. If the second main surface 1b of the waterproof membrane 1 has the same structure as the first main surface 1a, the above-mentioned effects can be obtained regardless of which side of the waterproof membrane 1 faces the opening 51 of the object 50, so there is no need to be careful about mixing up the main surfaces, improving handleability.

The material that constitutes the support layer 3 is, for example, metal, resin, or a composite material of these. Because it has excellent strength as a support layer 3, the material that constitutes the support layer 3 is preferably metal. Examples of metal include aluminum and stainless steel. Examples of resin include various resins such as polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate (PET)), polyamide (various aliphatic polyamides and aromatic polyamides, including nylon), polycarbonate, and polyimide.

A specific example of the support layer 3 is a metal plate having one or more through holes connecting the first main surface 3a and the second main surface 3b. A support layer 3 that is a metal plate has particularly excellent strength. Furthermore, when the support layer 3 is a metal plate, the rigidity and handleability of the waterproofing member 20 can be improved. The through holes extend, for example, in the thickness direction of the support layer 3. A metal plate having two or more through holes is preferred, as this results in a waterproofing member 20 that achieves a higher level of both sound transmission properties and strength. The through holes may be present at least in the portion located in the non-bonding region J2.

If the support layer 3 has two or more through holes, the openings of each through hole may be regularly arranged or irregularly positioned on the main surface of the metal plate when viewed from a direction perpendicular to the main surface.

The opening shape of the through hole, when viewed from a direction perpendicular to the main surface of the metal plate, is, for example, a circle (including an approximate circle), an ellipse (including an approximate ellipse), or a polygon including a square and a rectangle. The corners of the polygon may be rounded. However, the opening shape of the through hole is not limited to the above examples. When there are two or more through holes, the opening shapes of the respective through holes may be the same or different.

One example of a metal plate with two or more through holes is a perforated metal. Perforated metal is a metal plate in which through holes are created by punching (press-punching).

The aperture ratio of the support layer 3, which is the metal plate, is, for example, 1 to 80%, or may be 1 to 40%, or even 1 to 30%. When the aperture ratio is within these ranges, a waterproof member 20 can be obtained that achieves both high levels of sound transmission properties and strength. The aperture ratio of the support layer 3, which is the metal plate, is the ratio of the area of the openings of all the through holes present on the main surface to the area of the main surface of the support layer 3.

Another example of the support layer 3 is a mesh or net made of metal, resin, or a composite material thereof.

The breathability in the thickness direction of the support layer 3 is usually higher than that of the waterproof membrane 1. The breathability in the thickness direction of the support layer 3, expressed in terms of air permeability (Fragile air permeability) determined in accordance with Air Permeability Measurement Method A (Fragile method) specified in JIS L1096:2010, is, for example, 10 cm ³ /(cm 2 ·sec) or more, and may be 100 cm ³ /(cm ² ·sec) or ^more , 300 cm ³ /(cm ² ·sec) or more, or even greater than 500 cm ³ /(cm ² ·sec). The upper limit of the breathability in the thickness direction of the support layer 3, expressed in terms of Frazier air permeability, is, for example, 1000 cm ³ /(cm ² ·sec) or less.

Even if the size of the support layer 3 is less than the size of the test piece used in the Frazier method (approximately 200 mm x 200 mm), it is possible to evaluate the Frazier air permeability by using a measuring jig that limits the area of the measurement area. One example of a measuring jig is a resin plate with a through-hole formed in the center that has a cross-sectional area corresponding to the area of the desired measurement area. For example, a measuring jig with a through-hole formed in the center that has a circular cross-section with a diameter of 1 mm or less can be used.

The strength of the support layer 3 is usually higher than the strength of the waterproof membrane 1.

In the example shown in Figures 7 and 8, the bonding layer 21 is annular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the bonding layer 21 is not limited to the example shown in Figures 7 and 8.

In the example shown in Figures 7 and 8, the adhesive layer 22 is annular when viewed from a direction perpendicular to the main surface of the waterproof membrane 1. However, the shape of the adhesive layer 22 is not limited to the example shown in Figures 7 and 8.

As shown in Figures 7 and 8, the bonding layer 21 and the adhesive layer 22 may be annular and have the same bonding area.

The bonding layer 21 is, for example, a pressure-sensitive adhesive layer. However, the configuration of the bonding layer 21 is not limited as long as it is possible to form the bonding region J1 and the non-bonding region J2. The bonding layer 21, which is a pressure-sensitive adhesive layer, can be formed, for example, by applying a known pressure-sensitive adhesive or adhesive to the peripheral edge of the first main surface 1a of the waterproof membrane 1. The bonding layer 21 may be made of double-sided adhesive tape. That is, the waterproof membrane 1 and the support layer 3 may be bonded together in the bonding region J1 using double-sided adhesive tape. When the bonding layer 21 is made of double-sided adhesive tape, the bonding between the waterproof membrane 1 and the support layer 3 is more reliable, further improving the waterproofness of the waterproof member 20. In addition, it is easier to control the distance between the waterproof membrane 1 and the support layer 3 in the non-bonding region J2.

A known double-sided adhesive tape can be used for the double-sided adhesive tape that constitutes the bonding layer 21. The substrate of the double-sided adhesive tape is, for example, a resin film, nonwoven fabric, or foam. There are no limitations on the resin that can be used for the substrate, and examples include polyester (PET, etc.), polyolefin (polyethylene, etc.), and polyimide. Various adhesives, such as acrylic adhesives and silicone adhesives, can be used for the adhesive layer of the double-sided adhesive tape. It is preferable to use an acrylic adhesive for the adhesive layer, as this improves the bonding strength between the waterproof membrane 1 and the support layer 3. The double-sided adhesive tape may also be a thermal adhesive tape.

The thickness of the bonding layer 21 is, for example, 150 μm or less. The upper limit of the thickness of the bonding layer 21 may be 125 μm, 100 μm, 75 μm, or even 50 μm. The lower limit of the thickness of the bonding layer 21 is not particularly limited. The lower limit of the thickness of the bonding layer 21 may be, for example, 5 μm, 10 μm, 20 μm, or even 30 μm.

The materials described for the adhesive layer 2 in the waterproofing member 10 can be used as materials for the adhesive layer 22.

The material of the adhesive layer 22 may be the same as the material of the bonding layer 21. For example, the same double-sided tape may be used for the adhesive layer 22 and the bonding layer 21.

[Method of manufacturing waterproof member]
The waterproof member 20 described above can be manufactured, for example, by the following method. The manufacturing method will be described below using the waterproof member 20 shown in FIG. 7 as an example.

The manufacturing method described for the waterproof member 10 makes it possible to obtain a waterproof membrane 1 that includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and in which the first main surface 1a of the waterproof membrane 1 has a region R1a whose arithmetic mean height Sa is 0.20 μm or greater.

Next, a plate-shaped raw material for forming the support layer 3, a first adhesive sheet (e.g., double-sided tape) for forming the bonding layer 21, and a second adhesive sheet (e.g., double-sided tape) for forming the adhesive layer 22 are prepared. Holes corresponding to the sound-transmitting areas 4 are formed in advance in the first and second adhesive sheets. The waterproof membrane 1, first adhesive sheet, plate-shaped raw material, and second adhesive sheet are bonded together in this order so that the second main surface 1b of the waterproof membrane 1 is the outermost surface, and then punched into a predetermined shape to obtain the waterproof member 20.

The installation method of the waterproofing members 10, 20 is not particularly limited as long as it is capable of protecting the acoustic components. For example, the waterproofing members 10, 20 may be directly attached and fixed to the acoustic components to which they are applied using adhesive layers 2, 22. Alternatively, the waterproofing members 10, 20 may be attached and fixed to a housing that houses the acoustic components to which they are applied using adhesive layers 2, 22. In this case, for example, as shown in Figures 3 and 9, the waterproofing members 10, 20 are fixed to the object 50 by adhesive layers 2, 22 so that the waterproof membrane 1 closes an opening 51 provided in the object 50. Note that the opening 51 provided in the object 50 is located at a position corresponding to the acoustic component and is provided for the purpose of allowing sound to pass through.

In this embodiment, the waterproof member 10 is described as having a waterproof membrane 1 provided with a pressure-sensitive adhesive layer 2, but the waterproof member 10 does not have to have a pressure-sensitive adhesive layer 2. In that case, the waterproof member 10 can be installed in a predetermined position by sandwiching and fixing the waterproof membrane 1 with an O-ring or the like, or by fixing with resin sealing. In this embodiment, the waterproof member 20 is described as having a pressure-sensitive adhesive layer 22 provided with the support layer 3, but the waterproof member 20 does not have to have a pressure-sensitive adhesive layer 22. In that case, the waterproof member 20 can be installed in a predetermined position by sandwiching and fixing the laminate composed of the waterproof membrane 1, bonding layer 21, and support layer 3 with an O-ring or the like, or by fixing with resin sealing.

Although not shown in the figures, the waterproofing members 10 and 20 may further include a net or nonwoven fabric on the second main surface 1b of the waterproof membrane 1 for dust prevention purposes.

Second Embodiment
FIG. 11 shows an example of a waterproof member according to the second embodiment. The waterproof member 30 shown in FIG. 11 includes a waterproof membrane 1. As shown in FIG. 11, the waterproof member 30 is disposed inside a microelectromechanical system (MEMS) 60 for use, for example. The MEMS 60 includes a substrate 61 having an opening 611 that functions as a sound vent, a MEMS die 62 having a diaphragm 621, and a cap (cover) 63 that covers the MEMS die 62. The waterproof member 30 is disposed inside the MEMS 60 so as to cover the opening 611 of the substrate 61. The waterproof membrane 1 has a first main surface 1a facing the diaphragm 621 and a second main surface 1b opposite the first main surface 1a. Although not shown, the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11. The first main surface 1a of the waterproof membrane 1 has a region R1a having an arithmetic mean height Sa of 0.20 μm or more.

As shown in FIG. 11 , in the second embodiment, when the waterproof membrane 1 is positioned so as to cover the opening 611 of the substrate 61, the second main surface 1b of the waterproof membrane 1 faces the opening 611. The waterproof membrane 1 provided in the waterproof member 30 of the second embodiment has the same configuration as the waterproof membrane 1 provided in the waterproof member 10 of the first embodiment, except that the second main surface 1b faces the opening 611.

As shown in Figure 11, when the waterproof member 30 is positioned to cover the opening 611, the second main surface 1b of the waterproof membrane 1 and the opening surface 611s face each other via a space that contacts the second main surface 1b and the opening surface 611s.

In a waterproof member 30 in which the waterproof membrane 1 includes a main body 11 and particles 12 located closer to the first main surface 1a than the main body 11, and the first main surface 1a of the waterproof membrane 1 has a region R1a where the arithmetic mean height Sa is 0.20 μm or greater, the contact area between the first main surface 1a and the MEMS die 62 can be reduced when the waterproof membrane 1 is deformed by being pressed against the MEMS die 62 due to the application of pressure such as water pressure. As a result, after the pressure is released, the first main surface 1a of the waterproof membrane 1 easily separates from the MEMS die 62 and returns to its original shape. In other words, the deformation of the waterproof membrane 1 is easily recovered. Therefore, the waterproof member 30 of this embodiment is suitable for suppressing a decrease in sound transmission characteristics.

Inside 60i of MEMS 60, waterproof membrane 1 is arranged with opening surface 611s of substrate 61 as the placement surface, with the first main surface 1a of waterproof membrane 1 facing MEMS die 62. Waterproof membrane 1 is fixed to MEMS die 62 via adhesive layer 2, and is also fixed to opening surface 611s of substrate 61 via adhesive layer 65. Adhesive layer 65 is located on the opposite side of waterproof membrane 1 from adhesive layer 2. Furthermore, adhesive layer 65 overlaps adhesive layer 2 when viewed from a direction perpendicular to the main surface of waterproof membrane 1 (in the example of Figure 11, it coincides with adhesive layer 2). MEMS 60 may include any components other than those described above.

Figure 11 shows a state in which a MEMS 60 is placed in an opening 551 in a housing 55 of an electronic device or the like. The MEMS 60 in Figure 11 is a bottom-port (bottom opening) type microphone element. The MEMS 60 is bonded to the opening 551 in the housing 55. In the example of Figure 11, a printed circuit board (PCB) 56 having an opening 561 is bonded to the housing 55, and a substrate 61 of the MEMS 60 and the PCB 56 are connected via a connection part 59. The PCB 56 may be a flexible printed circuit (FPC). The connection part 59 electrically connects the substrate 61 and the PCB 56, and also fixes the substrate 61 to the PCB 56. For example, solder, conductive resin, etc. can be used as the connection part 59.

The present invention will be explained in more detail below using examples. The present invention is not limited to the examples shown below.

First, we will explain the evaluation method for the waterproof member produced in this example.

The arithmetic mean height Sa of the first main surface of the waterproof membrane and the average particle size of the particles on the first main surface of the waterproof membrane were evaluated using the method described above.

[Configuration of waterproof member and target object]
The configuration of the waterproof member 70 used in the examples and comparative examples will be described. FIG. 12 is a cross-sectional view showing the configuration of the waterproof member 70 used in the examples and comparative examples. As shown in FIG. 12, the waterproof member 70 included a waterproof membrane 7 and a support layer 9 spaced apart from the waterproof membrane 7 and having breathability in the thickness direction. The waterproof membrane 7 had a first main surface 7a and a second main surface 7b opposite the first main surface 7a. The support layer 9 had a first main surface 9a and a second main surface 9b facing the first main surface 7a of the waterproof membrane 7. The waterproof member 70 had a bonded region j1 where the waterproof membrane 7 and the support layer 9 were bonded by a bonding layer 81, and a non-bonded region j2 surrounded by the bonded region j1 when viewed perpendicular to the main surface of the waterproof member 70. In the non-bonded region j2, the support layer 9 was spaced apart from the waterproof membrane 7. The support layer 9 was configured to be attachable to an opening via a pressure-sensitive adhesive layer 82 bonded to the first main surface 9a. An adhesive layer 83 having the same shape as the adhesive layer 82 was bonded to the second main surface 7b of the waterproof membrane 7. Note that, since the surface structure of the first main surface 7a of the waterproof membrane 7 varies depending on the examples and comparative examples, the depiction of the surface structure of the first main surface 7a of the waterproof membrane 7 is omitted in Fig. 12.

(Method for measuring insertion loss IL and insertion loss difference IL _D )
The method for measuring the insertion loss IL and the insertion loss difference IL _D of a waterproofing member for a sound with a frequency of 1 kHz will be described with reference to Fig. 13. The insertion loss IL was measured by the following method using a simulated housing that imitates the housing of a mobile phone shown in Fig. 13.

As shown in Figures 13A and 13B, a speaker unit 135 was fabricated to be housed in a simulated housing. Specifically, the following steps were taken: A speaker 140 (Star Micronics SCC-16A), which serves as the sound source, and fillers 130a, 130b, and 130c, made of urethane sponge, were prepared to house the speaker 140 and prevent unnecessary diffusion of sound from the speaker (to minimize sound that is input to the evaluation microphone without passing through the waterproof material sample being evaluated). Filler 130a had a sound-passing opening 132 with a circular cross-section and a diameter of 5 mm formed in its thickness direction. Filler 130b had a notch shaped to match the shape of the speaker 140 and a notch to house the speaker cable 142 and lead the speaker cable 142 out of the speaker unit 135. Next, fillers 130c and 130b were placed on top of each other, and the speaker 140 and speaker cable 142 were placed in the cutout of filler 130b (see Figure 13(A)). Next, filler 130a was placed on top of it so that sound could be transmitted from the speaker 140 to the outside of the speaker unit 135 through the sound passage 132, resulting in the speaker unit 135 (see Figure 13(B)).

Next, as shown in Figure 13 (C), the speaker unit 135 prepared above was housed inside a simulated housing 160 (made of polystyrene, outer dimensions 60 mm x 50 mm x 28 mm) that resembles the housing of a mobile phone. Specifically, the process is as follows: The prepared simulated housing 160 consists of two parts 160a and 160b, and parts 160a and 160b can be fitted together. Part 160a is provided with a sound vent 162 (having a circular cross section with a diameter of 1 mm) that transmits sound emitted from the speaker unit 135 housed inside to the outside of the simulated housing 160, and a conduction hole 164 that leads the speaker cable 142 to the outside of the simulated housing 160. By fitting parts 160a and 160b together, a space with no openings other than the sound vent 162 and the conduction hole 164 is formed inside the simulated housing 160. The manufactured speaker unit 135 was placed on part 160b, and then parts 160a and 160b were fitted together to house the speaker unit 135 inside the simulated housing 160. At this time, the sound vent 132 of the speaker unit 135 was aligned with the sound vent 162 of part 160a so that sound could be transmitted from the speaker 140 to the outside of the simulated housing 160 through both sound vents 132, 162. The speaker cable 142 was pulled out to the outside of the simulated housing 120 through the conduction hole 164, which was then sealed with putty.

13D, sample S of the waterproof member 70 (with a non-bonded region j2 having an area of 1.8 mm ² ) was fixed to the sound hole 162 of the simulated housing 160 with the adhesive layer 83 on the waterproof membrane 7 side. Sample S was fixed so that the entire non-bonded region j2 of sample S was located within the opening of the sound hole 162 when viewed from a direction perpendicular to the main surface of the waterproof membrane 1.

Next, as shown in Figure 13 (E), a microphone 150 (SPU0410LR5H, manufactured by Knowles Acoustics) was fixed to the support layer side of sample S so as to cover the non-bonded area j2 of sample S. The microphone 150 was fixed using an adhesive layer 82 on the support layer 9 side of sample S. The distance between the speaker 140 and microphone 150 when fixed varied by up to approximately 2 mm depending on the thickness of the waterproof material sample being evaluated, but was in the range of approximately 22 mm to 24 mm. Next, the speaker 140 and microphone 150 were connected to an acoustic evaluation device (B&K Multi-analyzer System 3560-B-030), and the SSR (Solid State Response) mode (test signal 20 Hz to 20 kHz, sweep up) was selected and executed as the evaluation method to evaluate the insertion loss of sample S for a sound with a frequency of 1 kHz. The insertion loss was automatically determined from the test signal input to the speaker 140 from the acoustic evaluation device and the signal received by the microphone 150. In evaluating the insertion loss of sample S, the insertion loss value (blank value) when sample S was removed was determined in advance. The blank value was -38 dB at a frequency of 1 kHz. The insertion loss of sample S was the value obtained by subtracting this blank value from the measurement value from the acoustic evaluation device. The smaller the insertion loss value, the better the level (volume) of the sound output from the speaker 140 is maintained.

A water pressure application test was conducted in which a water pressure p of 0.5 MPa was applied for 10 minutes to the second main surface 7b of the waterproof membrane 7. The insertion losses IL _D1 and IL _D2 of sample S for a sound with a frequency of 1 kHz were measured before and after the water pressure application test. The difference (IL _D2 - _{IL D1} ) was considered to be the difference IL _D in insertion loss of the waterproof member for a sound with a frequency of 1 kHz.

[Example 1]
The waterproof membrane 7 of Example 1 was produced as follows. A thermosetting silicone resin (two-component thermosetting silicone resin, manufactured by Dow Corning Toray Co., Ltd.) was used as the raw material for the main body of the waterproof membrane 7. The thermosetting silicone resin was diluted with ethyl acetate to a solids concentration of 60 wt %, to obtain a coating liquid. The coating liquid was applied to the surface of a release liner (Mitsubishi Plastics, Inc., MRS50), and then dried at 130°C for 3 minutes. After drying, the release liner was removed. This resulted in a sheet-like main body. The main body was a non-porous membrane.

Next, particles were placed on one surface of the main body. The particles used were a composite of silicone rubber particles coated with silicone resin (KPM-600, manufactured by Shin-Etsu Chemical Co., Ltd.: average particle size 5 μm). A silicone oligomer crosslinked body (KR-4000G, manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the raw material for the coating layer. A dispersion was obtained by dispersing the particles and the silicone oligomer crosslinked body in an IPA solution so that the particle concentration was 0.7 wt% and the silicone oligomer crosslinked body concentration was 3.7 wt%. The dispersion was applied to one surface of the main body and then air-dried at room temperature (25°C). After drying, the membrane was heated at 160°C for 10 minutes. In this way, the waterproof membrane 7 of Example 1 was obtained. The surface to which the dispersion was applied was designated the first principal surface 7a.

Next, a support layer 9 was attached to the waterproof membrane 7. The support layer 9 was a 100 μm-thick punched metal made of SUS304 stainless steel (opening ratio: 15%, thickness-direction Frazier air permeability: 0.26 cm ³ /sec/cm ² or more, in-plane air resistance: 300,000 sec/100 mmL or more, each through-hole having a circular opening with a diameter of 0.2 mm when viewed perpendicular to the main surface). Double-sided tape (Nitto Denko Corporation, No. 5303W) was used as the first adhesive sheet for forming the bonding layer 81, the second adhesive sheet for forming the adhesive layer 82 on the support layer side, and the third adhesive sheet for forming the adhesive layer 83 on the waterproof membrane side. Circular holes with an inner diameter of 1.6 mm, corresponding to the sound-transmitting areas, were pre-formed in each adhesive sheet. The second adhesive sheet, punched metal, first adhesive sheet, waterproof membrane 7, and third adhesive sheet were laminated together in this order so that the second main surface 7b of the waterproof membrane 7 was the outermost surface, and then punched into a circular shape with an outer diameter of 5 mm. In this way, the waterproof member 70 of Example 1 was obtained. In the waterproof member 70 of Example 1, particles were present over the entire first main surface 7a of the waterproof membrane 7.

[Example 2]
The particles used were silicone resin particles (KPM-590, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 2 μm). Except for this, the waterproof membrane 7 and the waterproof member 70 of Example 2 were produced in the same manner as in Example 1.

Figure 14A shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 2 (10,000x magnification). Figure 14B shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 2 (1,000x magnification).

[Example 3]
The particles used were silica particles (KE-P100, manufactured by Nippon Shokubai Co., Ltd., average particle size 1 μm). Except for this, the waterproof membrane 7 and the waterproof member 70 of Example 3 were produced in the same manner as in Example 1.

Figure 15A shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 3 (10,000x magnification). Figure 15B shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 3 (1,000x magnification).

[Example 4]
The particles used were silicone resin particles (X-52-854, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 0.7 μm). Except for this, the waterproof membrane 7 and the waterproof member 70 of Example 4 were produced in the same manner as in Example 1.

Figure 16A shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 4 (10,000x magnification). Figure 16B shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 4 (1,000x magnification).

[Example 5]
The particles used were silica particles (KE-P50, manufactured by Nippon Shokubai Co., Ltd., average particle size 0.5 μm). Except for this, the waterproof membrane 7 and the waterproof member 70 of Example 5 were produced in the same manner as in Example 1.

Figure 17A shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 5 (10,000x magnification). Figure 17B shows the results of SEM observation of the first main surface 7a of the waterproof membrane 7 of Example 5 (1,000x magnification).

[Comparative Example 1]
When manufacturing the waterproof membrane 7, particles were not placed on one surface of the main body. That is, the main body of Example 1 was used as the waterproof membrane 7 of Comparative Example 1. Except for this, the waterproof membrane 7 and waterproof member 70 of Comparative Example 1 were manufactured in the same manner as in Example 1.

[Comparative Example 2]
A dispersion of only the silicone oligomer crosslinked body in an IPA solution was applied to one surface of the main body so that the concentration of the silicone oligomer crosslinked body became 4.3 wt %. In other words, when producing the waterproof membrane 7, only the coating layer was formed on one surface of the main body. Except for this, the waterproof membrane 7 and waterproof member 70 of Comparative Example 2 were produced in the same manner as in Example 1.

[Comparative Example 3]
As a release liner, a release embossed PET film having an uneven surface (PG-84 (60° houndstooth dot pattern: embossing height 24 μm, pattern pitch 350 μm) manufactured by Godo Resin Industries Co., Ltd.) was used. As a result, when producing the waterproof membrane 7, the uneven surface was transferred to one surface of the main body. No particles were placed on one surface of the main body. In other words, the main body having an uneven surface on one surface was used as the waterproof membrane 7 of Comparative Example 1. Other than this, the waterproof membrane 7 and waterproof member 70 of Comparative Example 3 were produced in the same manner as in Example 1.

[Reference example 1]
Silicone resin particles (X-52-854, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size 0.7 μm) were used as the particles. The particles and the crosslinked silicone oligomer were dispersed in an IPA solution so that the particle concentration was 30 wt % and the crosslinked silicone oligomer concentration was 3.7 wt %, to obtain a dispersion. Apart from these, the waterproof membrane 7 of Reference Example 1 was produced in the same manner as in Example 1. However, in Reference Example 1, bonding between the first main surface 7a of the waterproof membrane 7 and the bonding layer 81 could not be ensured, and the waterproof member 70 could not be produced.

The arithmetic mean height Sa of the first principal surface 7a and the average particle size of the particles on the first principal surface 7a were evaluated for the waterproof membranes 7 of Examples 1 to 5, Comparative Examples 1 to 3, and Reference Example 1. The results are shown in Table 1.

A water pressure test was conducted on the waterproof members 70 of Examples 1 to 5 and Comparative Examples 1 to 3, and the insertion loss IL _D1 before the water pressure test and the insertion loss IL _D2 after the water pressure test were measured. The difference between these values (IL _D2 - IL _D1 ) was calculated as the difference in insertion loss IL _D. In addition, after the water pressure p in the water pressure test was released, observation was performed using a microscope to determine whether the deformation of the first main surface 7a of the waterproof membrane 7 toward the second main surface 9b of the support layer 9 continued. The results are shown in Table 1.

As shown in Table 1, in the waterproof members 70 of Examples 1 to 5, in which the waterproof membrane 7 contains particles located closer to the first main surface 7a than the main body portion and the first main surface 7a of the waterproof membrane 7 has a region where the arithmetic mean height Sa is 0.20 μm or more, the waterproof membrane 7 did not continue to deform after the water pressure p was released, and the deformation of the waterproof membrane 7 was more easily recovered, compared to the preventing members 70 of Comparative Examples 1 to 3, which did not satisfy this requirement. The waterproof members 70 of Examples 1 to 5 had a difference in insertion loss IL _D before and after the water pressure application test of 2.5 dB or less. These results demonstrate that the waterproof member 70 in which the waterproof membrane 7 contains particles located closer to the first main surface 7a than the main body portion and the first main surface 7a of the waterproof membrane 7 has a region where the arithmetic mean height Sa is 0.20 μm or more is suitable for suppressing deterioration in sound transmission characteristics.

In the waterproof member 70 of Comparative Example 3, the arithmetic mean height Sa of the first main surface 7 a of the waterproof membrane 7 was 0.20 μm or more, but the difference in insertion loss IL _D was high at 6.3 dB. This is presumably because, in the waterproof member 70 of Comparative Example 3, the arithmetic mean height Sa of the first main surface 7 a was obtained by forming an uneven shape by transfer, rather than by the arrangement of particles, and therefore, when the waterproof membrane 7 was deformed by being pressed against the support layer 9 (punched metal), the contact area between the first main surface 7 a of the waterproof membrane 7 and the second main surface 9 b of the support layer 9 was not sufficiently reduced.

The reason why it was not possible to produce the waterproof member 70 in Reference Example 1 is that the arithmetic mean height Sa of the first main surface 7a of the waterproof membrane 7 was large, at 1 μm or more, which prevented bonding between the first main surface 7a and the bonding layer 81. This is thought to be because, in Reference Example 1, particles were present over the entire first main surface 7a of the waterproof membrane 7. Therefore, if the waterproof membrane 7 of Reference Example 1 is modified, for example, so that particles 12 are present only in the exposed region 10a, it is thought that it can be used without problem as a waterproof member of the present invention.

The technology of the present invention can be applied to a variety of electronic devices, including wearable devices such as smartwatches; various cameras; communication devices such as mobile phones and smartphones; and sensor devices.

Claims (15)

A waterproofing member that is disposed to close an opening of an object having an opening surface on which an opening is formed,
a waterproof membrane having a first main surface facing the opening when the waterproof membrane is disposed to close the opening and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
A waterproof member, wherein the first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more. The waterproof member according to claim 1, wherein the object includes a microelectromechanical system (MEMS). The waterproof member according to claim 1, wherein the average particle size of the particles in the region of the first main surface is in the range of 0.2 μm to 5 μm. The waterproof member according to claim 1, wherein the waterproof membrane further includes a coating layer covering at least a portion of the surface of the particles. The waterproof member according to claim 1, wherein the arithmetic mean height of the region of the first principal surface is less than 1 μm. The waterproof member according to claim 1, wherein the difference in insertion loss for a sound with a frequency of 1 kHz before and after a water pressure application test in which a water pressure of 0.5 MPa is applied to the second main surface of the waterproof membrane for 10 minutes is 2.5 dB or less. The waterproof member according to claim 1, wherein the main body of the waterproof membrane is a non-porous membrane. The waterproof member according to claim 1, wherein the main body of the waterproof membrane includes at least one material selected from the group consisting of silicone rubber, polyurethane, polyethylene terephthalate, polyimide, and polytetrafluoroethylene. The waterproof member according to claim 1, wherein the main body of the waterproof membrane includes an elastomer. The waterproof member according to claim 1, wherein, when the waterproof member is positioned to cover the opening, the first main surface of the waterproof membrane and the opening surface face each other via a space that contacts the first main surface and the opening surface. The waterproof member according to claim 1, further comprising an adhesive layer bonded to the first main surface of the waterproof membrane. The waterproof membrane further includes a support layer that is spaced apart from the waterproof membrane and has breathability in the thickness direction.
The waterproof member according to claim 1 , wherein the support layer is positioned between the waterproof membrane and the object when the waterproof member is disposed so as to cover the opening. the support layer has a first main surface facing the opening when the waterproofing member is disposed so as to close the opening and a second main surface opposite to the first main surface,
The waterproof member is
a bonding layer that bonds the first main surface of the waterproof membrane and the second main surface of the support layer;
The waterproof member according to claim 12 , further comprising: a pressure-sensitive adhesive layer bonded to the first main surface of the support layer. A waterproof member disposed inside a microelectromechanical system (MEMS) including a substrate having an opening functioning as a sound vent, a MEMS die having a vibration plate, and a cap covering the MEMS die, the waterproof member comprising:
a waterproof membrane having a first main surface facing the diaphragm when the waterproof membrane is disposed so as to close the opening and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
A waterproof member, wherein the first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more. A waterproofing member that is disposed so as to close an opening of an object having an opening surface on which an opening is formed,
a waterproof membrane having a first main surface and a second main surface opposite to the first main surface;
the waterproof membrane includes a main body portion and particles located closer to the first main surface than the main body portion,
The first main surface of the waterproof membrane has a region having an arithmetic mean height of 0.20 μm or more,
When the waterproof membrane is disposed so as to close the opening, the first main surface or the second main surface of the waterproof membrane faces the opening.
Waterproofing material.