WO2024219471A1 - Circuit board - Google Patents

Abstract

This circuit board has a first substrate and a second substrate. The first substrate includes a ceramic material, a metal material, a carbon material, and a composite that combines two or more thereof. The second substrate includes an organic resin as a main component, has a copper foil wiring on the surface thereof, and is laminated on the first substrate.

Description

Wiring Board

The disclosed embodiment relates to a wiring board.

　Traditionally, ceramics have been widely used as wiring boards for mounting various semiconductor elements such as LSIs. This is because ceramics have high rigidity and a thermal expansion coefficient close to that of semiconductor elements. For this reason, wiring boards that use highly rigid materials such as ceramics for the insulating layer are less likely to deform even when the semiconductor elements generate heat when they are operating, and they exhibit high mechanical and dynamic reliability.

JP 2017-188581 A

The wiring board according to one aspect of the embodiment has a first substrate and a second substrate. The first substrate contains any of the following materials: ceramic material, metal material, carbon material, and a composite of two or more of these materials. The second substrate contains an organic resin as a main component, has copper foil wiring on its surface, and is laminated on the first substrate.

FIG. 1 is an exploded perspective view showing an example of a wiring board according to a first embodiment. FIG. 2 is a perspective view illustrating an example of the wiring board according to the first embodiment. FIG. 3 is a cross-sectional view taken along line AA of FIG. FIG. 4 is a cross-sectional view taken along line BB of FIG. FIG. 5 is a cross-sectional view showing an example of a wiring board according to the second embodiment. FIG. 6 is a cross-sectional view showing an example of a wiring board according to the third embodiment. FIG. 7 is a cross-sectional view showing an example of a wiring board according to the fourth embodiment. FIG. 8 is a cross-sectional view showing an example of a wiring board according to the fifth embodiment. FIG. 9 is a cross-sectional view showing an example of a wiring board according to the sixth embodiment. FIG. 10 is a cross-sectional view illustrating an example of a wiring board according to the seventh embodiment.

In recent years, the number of transistors and gates formed in each element of various semiconductor elements such as LSIs has been increasing in order to accommodate performance improvements such as faster calculations and increased communication capacity.

In order to keep up with these changes in semiconductor elements, wiring boards are being forced to increase the number of connection terminals and wiring formed on them. For this reason, wiring boards are increasingly being required to have finer wiring and narrower pitches.

Therefore, there is a demand for wiring boards that are highly rigid like the ceramic wiring boards mentioned above, and that also enable finer wiring and narrower pitches.

Below, a detailed description will be given of a form for implementing a multilayer board according to the present disclosure (hereinafter, referred to as an "embodiment") with reference to the drawings. Note that the wiring board according to the present disclosure is not limited to this embodiment. Furthermore, each embodiment can be appropriately combined as long as the processing content is not contradictory.

In the following, identical or similar components are given the same reference numerals, and detailed explanations are omitted. In order to make the explanation easier to understand, the drawings referred to below may use expressions derived from an orthogonal coordinate system that defines mutually orthogonal X-axis, Y-axis, and Z-axis directions, with the positive Z-axis direction being the vertically upward direction.

First Embodiment
Fig. 1 is an exploded perspective view showing an example of a multilayer substrate according to the first embodiment. Fig. 2 is a perspective view showing an example of a wiring substrate according to the first embodiment. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 2. As shown in Figs. 1 to 3, the wiring substrate 1 according to the first embodiment has a first substrate 10 and a second substrate 20.

Here, the first substrate 10 has a base portion 11. The base portion 11 has a flat plate shape. The outer shape of the base portion 11 is preferably rectangular, for example. A rectangular shape is one that has a square or rectangular basic shape.

The second substrate 20 also has a flat plate shape and its outer shape is rectangular. The second substrate 20 is layered on the first substrate 10. In other words, the first substrate 10 and the second substrate 20 form a laminate.

The first substrate 10 contains one of the following materials: a ceramic material, a metal material, a carbon material, or a composite of two or more of these materials. On the other hand, the second substrate 20 contains an organic resin as a main component.

In the wiring board 1, the second substrate 20 has copper foil wiring on its surface. The wiring board 1 is a laminate in which a substrate (second substrate 20) made of organic resin, on which copper foil wiring can be easily formed, is layered and integrated with a substrate (first substrate 10) that is more rigid than the second substrate 20.

In other words, the wiring board 1 is a structure in which a second substrate 20 made of an organic resin, which is easy to adhere to copper foil that allows fine wiring to be formed, and a first substrate 10, which is more rigid than the second substrate 20, are laminated together, so that the rigidity of the second substrate 20 is compensated for by the first substrate 10. Thus, the wiring board 1, which constitutes one aspect of the first embodiment, has high rigidity and can achieve finer wiring and narrower pitches.

Next, the wiring board 1 can also have the following configuration. First, the first substrate 10 constituting the wiring board 1 may have a convex portion 12 on the first surface 111 when one surface of the base portion 11 is the first surface 111. The convex portion 12 is disposed in the center of the first surface 111. In other words, it is preferable that the base portion 11 and the convex portion 12 are one piece.

The first substrate 10 may have a base portion 11 and a protruding portion 12. The base portion 11 may be flat.

The convex portion 12 is located on the first surface 111 of the base portion 11. The convex portion 12 may be an island-shaped structure located toward the center of the first surface 111, away from the outer edge 110 of the first surface 111. The convex portion 12 has a mounting surface 121. The mounting surface 121 is the upper surface of the convex portion 12 on which an electrical element can be mounted. Here, the upper surface of the convex portion 12 is an expression resulting from the fact that the upper surface faces in the positive direction of the Z axis, as shown in FIG. 1, for example. The mounting surface 121 may also be expressed as the upper surface when the wiring board 1 in FIG. 1 is turned upside down. In other words, the mounting surface 121 may also be expressed as the upper surface when the mounting surface 121 of the convex portion 12 faces in the negative direction of the Z axis.

The first substrate 10 may be made of, for example, a ceramic material, a metal material, a carbon material, or a composite of two or more of these materials. The ceramic material may be, for example, an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a glass ceramic sintered body, a crystallized glass in which crystal components are precipitated in a glass matrix, or a microcrystalline sintered body such as mica or aluminum titanate. The metal material may be, for example, copper, silver, palladium, gold, platinum, aluminum, chromium, nickel, cadmium-lead, selenium, manganese, tin, vanadium, lithium, cobalt, titanium, or the like. The carbon material may be, for example, graphite.

The first substrate 10 preferably has a base portion 11 and a protruding portion 12 that are integrated together. For example, it is preferable that there is no lamination interface between the base portion 11 and the protruding portion 12. In addition, it is preferable that there is no material other than the material that constitutes the first substrate 10, such as an adhesive, between the base portion 11 and the protruding portion 12.

The second substrate 20 is laminated on the first surface 111 of the first substrate 10. The second substrate 20 is flat, and has a second surface 201 and a third surface 202 located at both ends in the thickness direction. The second surface 201 is the surface of the second substrate 20 facing in the same direction as the mounting surface 121 of the first substrate 10. The third surface 202 is located on the opposite side to the second surface 201, and faces the first surface 111 of the first substrate 10.

The second substrate 20 has a through hole 21 that penetrates in the thickness direction.

The second substrate 20 contains an organic resin as a main component. The organic resin may be, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, an olefin resin, or a polyphenylene resin. The organic resin may be, for example, polytetrafluoroethylene (PTFE) or other fluororesins or polyphenylene ether resins. The second substrate 20 may contain components other than the organic resin.

The first substrate 10 and the second substrate 20 are positioned so that the through hole 21 of the second substrate 20 fits into the protrusion 12 of the first substrate 10.

For example, since the mounting surface 121 is located on the convex portion 12 formed on the first substrate 10, which has a higher rigidity than the second substrate 20, the electrical element mounted on the mounting surface 121 is less likely to deform. In particular, by using copper foil as the material for the wiring located on the second surface 201 of the second substrate 20, it is possible to make the wiring finer and narrower in pitch. Furthermore, since the copper foil wiring is provided on the second substrate 20, which has a lower rigidity than the first substrate 10, the accumulation of residual stress is small. Therefore, according to this embodiment, it is possible to obtain a wiring board 1 that is less likely to deform and allows for finer wiring and narrower pitch, for example, with a line width of 50 μm or less and a pitch of 100 μm (line distance of 50 μm) or less.

Also, as shown in FIG. 3, the mounting surface 121 of the convex portion 12 of the first substrate 10 and the second surface 201 located on the surface of the second substrate 20 may be flush with each other. When the second substrate 20 is placed on the first substrate 10, there is no portion of the second substrate 20 that protrudes above the convex portion 12 of the first substrate 10, so that, for example, the portion of the second substrate 20 that deforms can be reduced. Also, for example, because the deformation of the second substrate 20 is stopped by the convex portion 12, the entire second substrate 20 is less likely to deform.

If the mounting surface 121 and the second surface 201 are flush with each other, for example, when the mounting surface 121 and the second surface 201 are connected by wire bonding, the length of the bonding wire extending from the electrical element mounted on the mounting surface 121 to the wiring (element terminal) on the second surface 201 can be the shortest distance or a length close to this. This makes it possible to reduce the inductance in the bonding wire.

If, for example, a highly rigid metallic material is used as the first substrate 10, it becomes easier to make the mounting surface 121 and the second surface 201 flush.

FIG. 4 is a cross-sectional view taken along line B-B in FIG. 2. The second substrate 20 has copper foil wiring 30 on its surface.

The wiring 30 located on the second surface 201 may be embedded in the surface portion of the second substrate 20. For example, compared to a configuration in which the wiring 30 is disposed so as to protrude above the second surface 201 of the second substrate 20, a configuration in which the wiring 30 is embedded in the second substrate 20 makes it easier for the second substrate 20 and the wiring 30 to be subjected to mutual restraining forces. This makes the second substrate 20 less likely to deform.

In this way, in the wiring board 1, the second substrate 20 is laminated in a manner that it is attached to the first substrate 10, which has greater rigidity than the second substrate 20, and the second substrate 20 is restrained by the first substrate 10. The second substrate 20 is also restrained by the wiring 30 formed on its surface. Furthermore, the second substrate 20 is also restrained by the convex portion 12 of the first substrate 10. The area of the second substrate 20 close to the convex portion 12 is more susceptible to restraining forces in the planar direction than the peripheral area away from the convex portion 12.

Furthermore, the front surface 301 of the wiring 30 may be flush with the second surface 201, which is the surface of the second substrate 20. This makes the second substrate 20 even less susceptible to deformation. Here, the front surface 301 of the wiring 30 refers to the surface of the wiring 30 that is exposed from the second substrate 20 when the second substrate 20 is viewed in plan from a position above it.

The structure shown in FIG. 4 can be produced, for example, by transferring and pressurizing a copper foil wiring material that has been patterned in advance onto a PET film, onto a ceramic green sheet that will become the first substrate 10. If necessary, heating may be performed simultaneously with pressing.

Second Embodiment
Fig. 5 is a cross-sectional view showing an example of a wiring board according to the second embodiment. Fig. 5 does not show the entire wiring board 1, but only occupies a portion close to the periphery of the protrusion 12 provided on the first base material 10. As shown in Fig. 5, the second surface 201 may be closer to the first surface 111 than the mounting surface 121.

Since the thickness of the second substrate 20 is thinner than the thickness of the first substrate 10 where the convex portion 12 is located, the second substrate 20 is more easily restrained by the convex portion 12 and the base portion 11 of the first substrate 10, and is less likely to deform.

In addition, because the convex portion 12 protrudes beyond the second surface 201 of the second substrate 20, when the convex portion 12 is recognized by a camera, a part of the side surface of the convex portion 12 is easily visible, along with the ridge line that forms the edge of the mounting surface of the convex portion 12. Therefore, the wiring board 1 according to this embodiment makes it easy to recognize images, for example.

Note that FIG. 5 shows a configuration in which the second substrate 20 has the same thickness over the entire area where it is in contact with the first surface 111 of the first substrate 10, but this is not limiting, and for example, at least a portion of the second substrate 20 close to the convex portion 12 may be closer to the first surface 111 than the mounting surface 121. When the second substrate 20 has the same thickness, for example, the bias in deformation of the second substrate 20 and the variation in the amount of deformation are reduced.

The configuration shown in Figure 5 can be produced, for example, by using a rubber mold on the upper side of the lamination machine that is easily deformed when it hits the product.

Third Embodiment
6 is a cross-sectional view showing an example of a wiring board according to the third embodiment. As shown in FIG. 6, the surface (second surface 201) of the second base material 20, which is a portion close to the protrusion 12, may be located higher than the upper surface (mounting surface 121) of the protrusion 12. In other words, the second surface 201 may be located at a greater distance from the first surface 111 than the mounting surface 121.

Since the second substrate 20 is thick and the second surface 201 of the second substrate 20 is farther from the first surface 111 than the mounting surface 121 of the convex portion 12, the second substrate 20 has, for example, a portion that protrudes above the mounting surface 121 of the convex portion 12.

The second substrate 20 has a portion in the thickness direction of the first substrate 10 that is close to the first surface 111 of the first substrate 10 and is easily constrained by the first substrate 10, and a portion that is far from the first surface 111 or the mounting surface 121 of the convex portion 12 and is not easily constrained by the first substrate 10.

The portion of the second substrate 20 above the mounting surface 121 of the protrusion 12 serves as a part that relieves the stress that occurs when, for example, a bending load is applied to the wiring substrate 1, and can withstand both tensile stress and compressive stress. As a result, for example, even when a mechanical load is applied to the wiring substrate 1, damage to the substrate material and wiring is less likely to occur.

In addition, in this configuration, for example, the bonding wire (not shown) that connects between the electrical element (not shown) mounted on the mounting surface 121 and the connection terminal (not shown) formed on the second substrate 20 can be made linear, which leads to a reduction in inductance.

Note that FIG. 6 shows a configuration in which the second substrate 20 has the same thickness over the entire area where it contacts the first surface 111 of the first substrate 10, but this is not limiting. For example, at least a portion of the second substrate 20 close to the convex portion 12 may be at a greater distance from the first surface 111 than the mounting surface 121. When the second substrate 20 has the same thickness, for example, the bias in deformation of the second substrate 20 and the variation in the amount of deformation are reduced.

The configuration shown in Figure 6 can be produced, for example, by using an inverted convex mold/rubber mold.

Fourth Embodiment
3, when the surface of the protruding portion 12 constituting the first base material 10 that faces the same direction as the first surface 111 of the first base material 10 is defined as the upper surface (mounting surface 121), the protruding portion 12 has a side surface 122 that intersects with the upper surface (mounting surface 121) and a ridge portion 123A that connects the side surface 122 and the upper surface (mounting surface 121). The second base material 20 is preferably configured such that the inner wall 20A of the second base material 20 that faces the through hole 21 contacts the protruding portion 12 from the side surface 122 to the ridge portion 123A.

FIG. 7 is a cross-sectional view showing an example of a wiring board according to the fourth embodiment. As shown in FIG. 7, the wiring board 1 may have a so-called chamfered shape at the ridge portion 123A (see FIG. 3) connecting the side surface 122 of the convex portion 12 to the upper surface (mounting surface 121). In other words, as shown in FIG. 7, the wiring board 1 may have rounded corners where the side surface 122 and the upper surface (mounting surface 121) of the convex portion 12 intersect. In other words, the wiring board 1 shown in FIG. 7 may have a curved surface at the corner (corresponding to the ridge portion 123A) connecting the side surface 122 of the convex portion 12 to the upper surface (mounting surface 121).

In FIG. 7, ridge portion 123A may be disposed so as to extend in the direction into the depth of the paper on which FIG. 7 is drawn. Hereinafter, the rounded corner where side surface 122 and top surface (mounting surface 121) of protrusion 12 intersect is referred to as first R-chamfered portion 123. In other words, first R-chamfered portion 123 is the curved surface of the corner that connects side surface 122 to top surface (mounting surface 121) of protrusion 12.

As shown in FIG. 7, the protrusion 12 may have a side surface 122 and a first R-chamfered portion 123. The side surface 122 is a surface that intersects with the mounting surface 121. The first R-chamfered portion 123 is located on the ridge where the side surface 122 and the mounting surface 121 intersect, and is a portion that is curved in a convex shape.

The second substrate 20 may have an inner wall of the through hole 21 in contact with the side surface 122 of the convex portion 12 from the first R chamfered portion 123. Since the convex portion 12 of the first substrate 10 has the first R chamfered portion 123, the contact area between the inner wall of the through hole 21 of the second substrate 20 and the first substrate 10 is larger than when the ridge portion of the convex portion 12 is simply angular without the first R chamfered portion 123. This increases the fixing force of the second substrate 20 to the first substrate 10, making it less likely to deform. Therefore, according to the wiring board 1 of this embodiment, for example, the surface portion of the second substrate 20 on the mounting surface 121 side is less likely to peel off.

Fifth Embodiment
FIG. 8 is a cross-sectional view showing an example of a wiring board according to the fifth embodiment.

Following the explanation of FIG. 7, referring further to the wiring board 1 shown in FIG. 3, this wiring board 1 has a corner portion 124A where the first surface 111 of the first substrate 10 and the side surface 122 of the protrusion 12 are connected. It is preferable that the second substrate 20 contacts the corner portion 124A.

8, the wiring board 1 may have a corner 124A (see FIG. 3) that connects from the first surface 111 to the side surface 122 of the convex portion 12, which is curved concavely from the first surface 111 to the side surface 122 of the convex portion 12. In other words, as shown in FIG. 8, the wiring board 1 may have a rounded corner 124A where the first surface 111 and the side surface 122 of the convex portion 12 intersect.

In FIG. 8, the corner portion 124A may be disposed so as to extend in the direction of the depth of the paper on which FIG. 8 is drawn. Hereinafter, the portion of the corner portion 124A where the first surface 111 and the side surface 122 of the protrusion 12 intersect and which is rounded in a concave shape will be referred to as the second R-chamfered portion 124.

As shown in FIG. 8, the protrusion 12 may have a side surface 122 and a second R-chamfered portion 124. The side surface 122 is a surface that intersects with the mounting surface 121. The second R-chamfered portion 124 is located at the corner where the side surface 122 and the first surface 111 intersect, and is a concavely curved portion.

The second substrate 20 may have the inner wall of the through hole 21 in contact with the side surface 122 of the convex portion 12 from the second R chamfered portion 124. Since the convex portion 12 of the first substrate 10 has the second R chamfered portion 124, the contact area between the inner wall of the through hole 21 of the second substrate 20 and the first substrate 10 is larger than when the corner of the convex portion 12 is simply angular and does not have the second R chamfered portion 124. This increases the fixing force of the second substrate 20 to the first substrate 10, making it less likely to deform.

The first substrate 10 shown in Figures 7 and 8 can be formed, for example, by producing a ceramic sintered body using a green sheet formed using a dedicated mold.

Sixth Embodiment
9 is a cross-sectional view showing an example of a wiring board according to the sixth embodiment. As shown in FIG. 9, the protrusion 12 may have a side surface 122, a first R-chamfered portion 123, and a second R-chamfered portion 124. The side surface 122 is a surface that intersects with the mounting surface 121. The first R-chamfered portion 123 is a portion that is located at a ridge where the side surface 122 and the mounting surface 121 intersect, and is curved in a convex shape. The second R-chamfered portion 124 is a portion that is located at a corner where the side surface 122 and the first surface 111 intersect, and is curved in a concave shape.

The second substrate 20 may have the inner wall of the through hole 21 in contact with the side surface 122 of the protrusion 12 from the first R chamfered portion 123 to the second R chamfered portion 124.

Since the convex portion 12 of the first substrate 10 has the first R chamfered portion 123, the contact area between the inner wall of the through hole 21 of the second substrate 20 and the first substrate 10 is larger than when the ridge portion of the convex portion 12 is simply angular without the first R chamfered portion 123. Also, since the convex portion 12 of the first substrate 10 has the second R chamfered portion 124, the contact area between the inner wall of the through hole 21 of the second substrate 20 and the first substrate 10 is larger than when the corner of the convex portion 12 is simply angular without the second R chamfered portion 124. This increases the fixing force of the second substrate 20 to the first substrate 10, making it less likely to deform.

Seventh Embodiment
Fig. 10 is a cross-sectional view showing an example of a wiring board according to the seventh embodiment. As shown in Fig. 10, the protrusion 12 has a side surface 122 intersecting with a mounting surface 121. In this case, the inner wall facing the through hole 21 of the second base material 20 and the side surface 122 may be spaced apart.

For example, even when a highly heat-generating electrical element is mounted on the mounting surface 121 of the protrusion 12, heat from the electrical element is less likely to be transferred to the second substrate 20 that carries the wiring section, making it possible to suppress changes in the resistance of the wiring section due to temperature. In addition, since the amount of deformation due to thermal expansion of the second substrate 20 can be reduced, it is possible to stabilize the transmission characteristics of the wiring 30 (see FIG. 4). Furthermore, even if, for example, the resin used to mount the electrical element on the mounting surface 121 flows and spreads outward from the mounting surface 121, the resin is less likely to reach the second surface 201 of the second substrate 20, making it less likely that defects in the finish (appearance) of the wiring board 1 will occur.

The configuration shown in FIG. 10 can be produced, for example, by forming holes (through holes) larger than the protrusions 12 in advance in a hybrid sheet, which is the material of the second substrate 20, and maintaining this gap by elastic pressing. Also, before the second substrate 20 is superimposed on the first substrate 10, a silicone-based release agent, for example, may be applied to the side surface 122 of the protrusions 12 of the first substrate 10. The first substrate 10 to which the release agent has been applied may be less likely to shrink than the second substrate 20 when cooled after being pressurized and heated. This effect may be utilized to produce the wiring board 1 according to this embodiment.

Other Embodiments
In each of the above-described embodiments, the first substrate 10 may have a conductor. The first substrate 10 may have, as the conductor, for example, a via conductor extending in the thickness direction of the first substrate 10, wiring formed on at least one of the surface and the inside of the first substrate 10, a pad, or the like. When having such a configuration, for example, the material of the first substrate 10 may be a ceramic material.

(Production method)
An example of a method for manufacturing the wiring board 1 according to the present disclosure will be specifically described below. Note that the present disclosure is not limited to the wiring board 1 manufactured by the following manufacturing method.

[First substrate]
First, a green sheet was prepared. A mold was used to apply pressure to the green sheet, and a molded body was produced in which the protrusions were integrated on the base. Specifically, for example, a green sheet containing alumina particles and having a thickness of 800 μm was prepared, and a conductive paste was printed on a portion of the surface of each of the green sheets and the green sheet having the protrusions, at the portion that would become the joint of the electric element, to form a wiring ceramic sheet. The conductive paste used contained copper powder and tungsten powder as metal components.

Next, each of the wiring ceramic sheets that had been produced was fired. The firing conditions were a reducing atmosphere, a maximum temperature of 1600°C, and a holding temperature of 2 hours.

[Second substrate]
First, an uncured sheet (composite material) containing silica powder in a thermosetting epoxy resin was prepared. The amount of silica powder added was 150 parts by mass per 100 parts by mass of the epoxy resin.

Next, copper foil wiring was transferred onto the uncured sheet to create a wiring organic sheet. The copper foil wiring pattern used in the transfer method was made by attaching solid copper foil to a PET film and then etching it to create a pattern.

Then, the prepared wiring organic sheet was placed on top of the wiring ceramic sheet and pressurized and heated. The pressurized and heated conditions were, for example, a temperature of 200°C, a pressure of 0.1 MPa, and a heating time of 5 hours. In this way, the base body of the wiring board 1 was prepared. Next, the base body was cut to a specified size to obtain the wiring board 1.

[First R-chamfered portion/Second R-chamfered portion]
Here, the structure in which the protrusion 12 has the first R-chamfered portion 123 and/or the second R-chamfered portion 124 was produced by using a dedicated mold corresponding to the desired shape.

Furthermore, for the wiring board in which the surface of the second substrate near the convex portion is located lower than the upper surface of the convex portion, the wiring board in which the surface of the second substrate near the convex portion is located higher than the upper surface of the convex portion, the wiring board in which the convex portion has a first R chamfered portion, the wiring board in which the corner of the first substrate has a second R chamfered portion, and the wiring board in which the convex portion has a first R chamfered portion and a second R chamfered portion at the corner of the first substrate, a molded body was produced in which the thickness of the green sheet and the height of the convex portion were adjusted. Furthermore, for the wiring substrate in which the inner wall facing the through hole of the second substrate is located away from the side, a method was adopted in which a silicone-based release agent was applied to the surface of the convex portion and the wiring organic sheet was laminated in this state.

All of the wiring boards produced in this manner are highly rigid, and are capable of achieving finer wiring and narrower pitches. It has been confirmed that all of these wiring boards exhibit the above-mentioned effects, regardless of differences in the shapes of the convex portions and wiring organic sheets. This was confirmed by microscopic observation of the wiring, solder heat resistance tests, temperature cycle tests, and electrical property evaluations. These evaluations confirmed that the boards are at a level suitable for practical use, such as for driving semiconductor elements.

The present disclosure has been described in detail above, but it is not limited to the above-described embodiment, and various modifications and improvements are possible without departing from the gist of the present disclosure.

In one embodiment, (1) the wiring board has a first substrate and a second substrate,
The first substrate includes any one of a ceramic material, a metal material, a carbon material, and a composite material obtained by combining two or more of these materials;
The second base material contains an organic resin as a main component, has copper foil wiring on its surface, and is laminated on the first base material.

(2) In the wiring board according to (1) above, the first substrate integrally includes a base portion and a protruding portion that is island-shaped and located toward the center of the first surface away from an outer edge of the first surface when one surface of the base portion is defined as a first surface,
The second base material has a through hole penetrating in a thickness direction,
The second base material may be disposed such that the through hole fits into the protrusion of the first base material.

(3) In the wiring board according to (2), when a surface of the protrusion that faces the same direction as the first surface of the first base material is defined as an upper surface,
The upper surface and the front surface of the second base material may be flush with each other.

(4) In the wiring board according to (2) above, when a surface of the protrusion that faces the same direction as the first surface of the first base material is defined as an upper surface,
The surface of the second base member in a portion close to the protrusion may be located at a lower position than the upper surface of the protrusion.

(5) In the wiring board according to (2) above, when a surface of the protrusion that faces the same direction as the first surface of the first base material is defined as an upper surface,
A portion of the surface of the second base member that is close to the protrusion may be located higher than the upper surface of the protrusion.

(6) In the wiring substrate according to any one of (2) to (5) above, when a surface of the protrusion that faces the same direction as the first surface of the first base material is defined as an upper surface,
the protrusion has a side surface intersecting the upper surface and a ridge portion connecting the side surface and the upper surface,
An inner wall of the second base material facing the through hole may be in contact with a range extending from the side surface of the protrusion to the ridge portion.

(7) In the wiring board of (6) above, the ridge portion may be chamfered.

(8) In the wiring substrate according to any one of (2) to (5) above, when a surface of the protrusion that faces the same direction as the first surface of the first base material is defined as an upper surface,
The protrusion has a side surface intersecting with the upper surface,
the first base material has a corner portion where the first surface and the side surface of the protrusion are connected,
The second substrate may be in contact with the corner.

(9) In the wiring board of (8) above, the corner portion may have a concave curved shape from the first surface to the side surface of the protruding portion.

(10) In the wiring substrate according to any one of (2) to (5) above, when a surface of the protrusion that faces the same direction as the first surface of the first base material is defined as an upper surface,
the protruding portion has a side surface intersecting with the top surface, a first R-chamfered portion located at a ridge where the side surface intersects with the top surface, and a second R-chamfered portion located at a corner where the side surface intersects with the first surface and curved concavely,
An inner wall of the second base material facing the through hole may be in contact with an area extending from the side surface of the protrusion to the first R-chamfered portion and the second R-chamfered portion.

(11) In the wiring substrate according to any one of (2) to (10), when a surface of the protrusion that faces the same direction as the first surface of the first base material is defined as an upper surface,
The protrusion has a side surface intersecting with the upper surface,
An inner wall of the second base material facing the through hole may be located at a position spaced apart from the side surface.

(12) In any one of the wiring boards (1) to (11) above, the wiring may be embedded in a surface portion of the second substrate.

(13) In the wiring board of (12) above, the front surface of the wiring may be flush with the surface of the second substrate.

Further advantages and other aspects may be readily derived by those skilled in the art. Thus, the disclosure in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof.

REFERENCE SIGNS LIST 1 wiring substrate 10 first substrate 11 base portion 12 protruding portion 20 second substrate 21 through hole 30 wiring 111 first surface 121 mounting surface 122 side surface 123 first rounded chamfered portion 124 second rounded chamfered portion 201 second surface 202 third surface

Claims (13)

A first substrate and a second substrate are included.
The first substrate includes any one of a ceramic material, a metal material, a carbon material, and a composite material obtained by combining two or more of these materials;
The second base material contains an organic resin as a main component, has copper foil wiring on a surface thereof, and is laminated on the first base material. the first substrate integrally includes a base portion and a protruding portion that is in an island shape and is located toward the center of the first surface away from an outer edge of the first surface when one surface of the base portion is defined as a first surface,
The second base material has a through hole penetrating in a thickness direction,
The wiring board according to claim 1 , wherein the second base material is disposed such that the through hole fits into the protrusion of the first base material. When a surface of the protrusion facing the same direction as the first surface of the first base material is defined as an upper surface,
The wiring board according to claim 2 , wherein the upper surface and the front surface of the second base material are flush with each other. When a surface of the protrusion facing the same direction as the first surface of the first base material is defined as an upper surface,
The wiring board according to claim 2 , wherein the surface of the second base member in a portion close to the protrusion is located at a lower position than the upper surface of the protrusion. When a surface of the protrusion facing the same direction as the first surface of the first base material is defined as an upper surface,
The wiring board according to claim 2 , wherein the surface of the second base member in a portion close to the protrusion is located at a higher position than the upper surface of the protrusion. When a surface of the protrusion facing the same direction as the first surface of the first base material is defined as an upper surface,
the protrusion has a side surface intersecting the upper surface and a ridge portion connecting the side surface and the upper surface,
6. The wiring board according to claim 2, wherein an inner wall of the second base material facing the through hole is in contact with an area extending from the side surface of the protrusion to the ridge line portion. The wiring board according to claim 6 , wherein the ridge portion is chamfered. When a surface of the protrusion facing the same direction as the first surface of the first base material is defined as an upper surface,
The protrusion has a side surface intersecting with the upper surface,
the first base material has a corner portion where the first surface and the side surface of the protrusion are connected,
The wiring board according to claim 2 , wherein the second base material is in contact with the corner portion. The wiring board according to claim 8 , wherein the corner portion has a concave curved shape extending from the first surface to the side surface of the protruding portion. When a surface of the protrusion facing the same direction as the first surface of the first base material is defined as an upper surface,
the protruding portion has a side surface intersecting with the top surface, a first R-chamfered portion located at a ridge where the side surface intersects with the top surface, and a second R-chamfered portion located at a corner where the side surface intersects with the first surface and curved concavely,
The wiring board according to any one of claims 2 to 5, wherein an inner wall of the second base material facing the through hole is in contact with an area extending from the side surface of the protrusion to the first R-chamfered portion and the second R-chamfered portion. When a surface of the protrusion facing the same direction as the first surface of the first base material is defined as an upper surface,
The protrusion has a side surface intersecting with the upper surface,
11. The wiring board according to claim 2, wherein an inner wall of the second base material facing the through hole is located at a position spaced apart from the side surface. The wiring board according to claim 1 , wherein the wiring is embedded in a surface portion of the second base material. The wiring board according to claim 12 , wherein a front surface of the wiring is flush with a surface of the second base material.

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