JP2003014569A - Package for pressure detector - Google Patents

Abstract

(57) [Problem] To provide a high-sensitivity and small-sized pressure detecting device capable of detecting a small change in pressure with a large amount of deflection of an insulating plate. SOLUTION: An insulating base 1 on which a semiconductor element 3 is mounted on one main surface, a plurality of wiring conductors 5 provided on the insulating base 1 and electrically connected to electrodes of the semiconductor element 3, are provided. A substantially disk-shaped closed space S between the other main surface of the base 1
An insulating plate 2 joined to the insulating base 1 in a flexible state so as to form a wiring conductor 5, and a static conductive member 2 attached to the other main surface of the insulating base 1 and electrically connected to one of the wiring conductors 5 a. A first electrode 7 for forming a capacitance and an electrostatic capacitor attached to the inner main surface of the insulating plate 2 so as to face the first electrode 7 and electrically connected to the other one 5b of the wiring conductor 5 In a package for a pressure detecting device including a second electrode 8 for forming a capacitance, the insulating plate 2 is provided with undulations along the outer periphery of the closed space S.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detecting device package used for a pressure detecting device for detecting pressure. 2. Description of the Related Art Conventionally, a capacitance type pressure detecting device has been known as a pressure detecting device for detecting pressure. As shown in a sectional view of FIG. 3, for example, a capacitance type pressure sensing device 22 and a package 28 are provided on a wiring board 21 made of a ceramic material or a resin material.
And a semiconductor element 29 for arithmetic operation housed in the computer. The pressure-sensitive element 22 is made of, for example, an electrically insulating material such as a ceramic material.
An insulating substrate 24 having a concave portion to which
An insulating plate 26, which is joined in a flexible state on the upper surface of the insulating substrate 24 so as to form a sealed space between the insulating substrate 24 and the other electrode 25 for forming a capacitance on the lower surface, Each of the electrodes 23 and 25 for forming a capacitance includes an external lead terminal 27 for electrically connecting the electrode to the outside, and each of the capacitances is formed by bending the insulating plate 26 according to an external pressure. The capacitance formed between the forming electrodes 23 and 25 changes. An external pressure can be detected by subjecting this change in capacitance to arithmetic processing by the semiconductor element 29 for arithmetic operation. [0003] However, according to this conventional pressure detecting device, the pressure-sensitive element 22 and the semiconductor element 29 are not provided.
Are individually mounted on the wiring board 21, which increases the size of the pressure detection device and the pressure detection electrode.
The wiring between 23 and 25 and the semiconductor element 29 becomes longer,
There is a problem that the sensitivity is low because an unnecessary capacitance is formed between the long wires. Accordingly, the applicant of the present application has previously filed Japanese Patent Application No. 2000-178.
618, an insulating base having a mounting portion on which a semiconductor element is mounted on one main surface; and a plurality of insulating bases disposed on and inside the insulating base, each electrode of the semiconductor element being electrically connected. A wiring conductor, a first electrode for forming a capacitance, which is attached to a central portion of the other main surface of the insulating base, and is electrically connected to one of the wiring conductors; An insulating plate joined in a flexible state so as to form a sealed space with the central portion of the main surface, and an inner main surface of the insulating plate is attached to the first main surface so as to face the first electrode. Thus, a pressure detection device package including a second electrode for forming a capacitance electrically connected to another one of the wiring conductors has been proposed. According to this pressure detecting device package, a first electrode for forming a capacitance is provided on the other main surface of the insulating base having a mounting portion on which a semiconductor element is mounted on one main surface, and the first electrode is provided on the first electrode. Since the insulating plate having the opposing second electrode for capacitance formation on the inner surface thereof was joined in a flexible state so as to form a sealed space between the other main surface of the insulating base, The pressure-sensitive element is formed integrally with the package containing the semiconductor element. As a result, the pressure detection device can be made small and the wiring connecting the electrode for pressure detection and the semiconductor element is shortened. Unnecessary capacitance generated between the wirings can be reduced. However, according to the package for a pressure detecting device proposed in Japanese Patent Application No. 2000-178618, the insulating plate is made of a ceramic material having low flexibility and has a small amount of bending because it is a flat plate. There was a problem that it was difficult to detect the change. The present invention has been completed in view of the above-described problems, and has as its object to provide a high-sensitivity and high-sensitivity in which the amount of deflection of the insulating plate is large and a small change in pressure can be detected well. An object of the present invention is to provide a small-sized pressure detecting device. A package for a pressure detecting device according to the present invention includes an insulating base having a mounting portion on one side of which a semiconductor element is mounted, and a package disposed on the surface and inside of the insulating base. A plurality of wiring conductors to which each electrode of the semiconductor element is electrically connected, and a flexible state so as to form a substantially disk-shaped closed space between the other main surface of the insulating base. An insulating plate joined to the insulating base at the other end, and is attached to the other main surface of the insulating base in a closed space between the insulating base and the insulating plate, and is electrically connected to one of the wiring conductors. A first electrode for forming a capacitance, and a capacitance formation that is attached to an inner main surface of the insulating plate so as to face the first electrode and is electrically connected to another one of the wiring conductors. And a second electrode for pressure detection, comprising: It is characterized by having undulations along the outer periphery between them. According to the pressure detecting device package of the present invention, since the insulating plate has undulation along the outer periphery of the closed space, the undulation increases the amount of bending. Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view illustrating an example of an embodiment of a package for a pressure detection device according to the present invention.
1 is an insulating base, 2 is an insulating plate, and 3 is a semiconductor element. An insulating base 1 has a semiconductor element 3
Aluminum oxide-based sintered body having a concave portion 1a for accommodating therein and having a substantially circular concave portion 1c for forming a substantially disk-shaped closed space S between the upper surface center portion and an insulating plate 2 described later, A laminate made of a ceramic material such as an aluminum nitride-based sintered body, a mullite-based sintered body, or a glass-ceramic. For example, in the case of an aluminum oxide-based sintered body, aluminum oxide, silicon oxide, magnesium oxide, A ceramic raw material powder such as calcium oxide is mixed with an appropriate organic binder, a solvent, a plasticizer, and a dispersant to form a slurry, which is formed into a sheet by using a conventionally known doctor blade method. The ceramic green sheets are obtained, and then these ceramic green sheets are appropriately punched and processed.
The green ceramic molded body for the insulating base 1 is obtained by performing lamination processing and cutting processing, and the green ceramic molded body is manufactured by firing the green ceramic molded body together with a ceramic green sheet for the insulating plate 2 described later at a temperature of about 1600 ° C. You. The insulating substrate 1 has a mounting portion 1b on which the semiconductor element 3 is mounted at the center of the bottom surface of the concave portion 1a formed at the center of the lower surface thereof.
The semiconductor element 3 is encapsulated by mounting a resin sealing material 4 such as an epoxy resin in the recess 1a. In this example, the semiconductor element 3 is sealed by filling a resin sealing material 4 into the recess 1a. However, the semiconductor element 3 is provided with a lid made of metal or ceramic on the lower surface of the insulating base 1 in the recess 1a. May be sealed by joining them so as to close them. A plurality of wiring conductors 5 connected to the respective electrodes of the semiconductor element 3 are led out to the mounting portion 1b, and the wiring conductor 5 and the respective electrodes of the semiconductor element 3 are electrically connected to each other by a bonding wire 6 or the like. By connecting via the connection means, each electrode of the semiconductor element 3 and each metallized wiring conductor 5 are electrically connected. In this example, the electrodes of the semiconductor element 3 and the wiring conductors 5 are connected via the bonding wires 6, but the electrodes of the semiconductor element 3 and the wiring conductors 5 are connected by another type of electrical connection such as a solder bump. They may be connected by means. The wiring conductor 5 functions as a conductive path for electrically connecting each electrode of the semiconductor element 3 to an external electric circuit and a first electrode 7 and a second electrode 8, which will be described later. 1, and another part is an insulating base 1
And is electrically connected to the first electrode 7 and the second electrode 8. The electrodes of the semiconductor element 3 are electrically connected to these wiring conductors 5 via electrical connection means, and the semiconductor element 3 is sealed with a resin sealing material 4 or the like. The semiconductor element 3 housed inside is electrically connected to the external electric circuit by connecting the portion led out to the lower surface of the outer periphery of the base 1 to the wiring conductor of the external electric circuit board via an electric connection means such as solder. It will be. The wiring conductor 5 is made of a metal powder of tungsten, molybdenum, copper, silver or the like.
A metallized paste obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, dispersant, etc. to metal powder such as tungsten is applied to a ceramic green sheet for the insulating substrate 1 by using a conventionally known screen printing method. A predetermined pattern is formed on the inside and on the surface of the insulating substrate 1 by printing and applying the pattern and firing this together with the green ceramic molded body for the insulating substrate 1. In addition, on the exposed surface of the wiring conductor 5, in order to prevent the wiring conductor 5 from being oxidized and corroded and to make the connection between the wiring conductor 5 and an electrical connection means such as solder good, , The thickness is 1
A nickel plating layer having a thickness of about 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are sequentially applied. A first electrode 7 for forming a capacitance is attached to the bottom of the concave portion 1c formed at the center of the upper surface of the insulating base 1. The first electrode 7 is to form a capacitance for a pressure-sensitive element together with a second electrode 8 of the insulating plate 2 described later. The first electrode 7 has a wiring conductor 5
When the electrode of the semiconductor element 3 is connected to the wiring conductor 5a via an electrical connection means such as a bonding wire 6, the electrode of the semiconductor element 3 and the first electrode 7 are electrically connected. It is designed to be connected. The first electrode 7 is made of a metal powder of tungsten, molybdenum, copper, silver or the like.
A metallized paste obtained by adding a suitable organic binder, a solvent, a plasticizer, and a dispersant to a metal powder such as tungsten is mixed with an insulating substrate 1 by using a conventionally known screen printing method.
A ceramic green sheet for printing is applied and baked together with a green ceramic molded body for the insulating substrate 1 to form a predetermined pattern at the center of the upper surface of the insulating substrate 1. On the upper surface of the insulating substrate 1, an insulating plate 2 covering the recess 1c forms a substantially disk-shaped closed space S with the upper surface of the insulating substrate 1. 1 and joined together. The insulating plate 2 is made of a ceramic material such as an aluminum oxide-based sintered body, an aluminum nitride-based sintered body, a mullite-based sintered body, or a glass-ceramic, and has a thickness of about 0.01 to 5 mm, and has a thickness of about 0.01 to 5 mm. And functions as a pressure detecting diaphragm that bends in response to external pressure. When the insulating plate 2 is made of, for example, an aluminum oxide sintered body, an organic binder, a solvent, and a plastic suitable for a ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. A ceramic green sheet for the insulating plate 2 is obtained by adding and mixing an agent and a dispersant to form a slurry and forming the slurry into a sheet by employing a conventionally known doctor blade method. The sheet is subjected to an appropriate punching or cutting process and laminated on a green ceramic molded body for the insulating substrate 1, which is fired together with the green ceramic molded body for the insulating substrate 1 at a temperature of about 1600 ° C. It is manufactured by sintering and integration. A substantially circular second electrode 8 for forming a capacitance is attached to the lower surface of the insulating plate 2 so as to face the first electrode 7. The second electrode 8 functions as an electrode for forming a capacitance for a pressure-sensitive element together with the first electrode 7 described above. The other one 5b of the wiring conductor 5 is connected to the second electrode 8 so that the wiring conductor 5
When the electrode of the semiconductor element 3 is connected to the electrode b through an electrical connection means such as a bonding wire 6, the electrode of the semiconductor element 3 and the second electrode 8 are electrically connected. At this time, the first electrode 7 and the second electrode 8
It faces each other across a closed space S formed between the insulating base 1 and the insulating plate 2, and between them, the area of the first electrode 7 and the second electrode 8, and the first electrode 7 and the second A predetermined capacitance is formed according to the distance from the electrode 8. When an external pressure is applied to the upper surface of the insulating plate 2, the insulating plate 2 bends toward the insulating base 1 according to the applied pressure, and the distance between the first electrode 7 and the second electrode 8 changes. Since the capacitance between the first electrode 7 and the second electrode 8 changes, it functions as a pressure-sensitive element that detects a change in external pressure as a change in capacitance. Then, the change in the capacitance is transmitted to the semiconductor element 3 accommodated in the concave portion 1a via the wiring conductors 5a and 5b, and the magnitude of the external pressure is obtained by performing an arithmetic processing on the semiconductor element 3. Can be. The second electrode 8 is made of metallized metal powder such as tungsten, molybdenum, copper or silver, and is obtained by adding a suitable organic binder, solvent, plasticizer or dispersant to metal powder such as tungsten. The metallized paste is printed and applied to the ceramic green sheet for the insulating plate 2 by using a conventionally known screen printing method, and this is applied to the insulating plate 2.
By firing together with the ceramic green sheet for use, a predetermined shape facing the first electrode 7 is formed on the lower surface of the insulating plate 2. Furthermore, a dummy metallization layer 9 for undulation is attached to the outer periphery of the upper surface of the insulating plate 2 and has a substantially circular inner periphery and extends to a position corresponding to the outer periphery of the closed space S. Thus, a swell is formed along the outer periphery of the closed space S such that the central portion thereof is recessed and the outer peripheral portion rises. The dummy metallized layer 9 is made of metal powder metallized tungsten, molybdenum, copper, silver, etc.
A metallized paste obtained by adding a suitable organic binder, a solvent, a plasticizer, and a dispersant to a metal powder such as tungsten is mixed by printing onto a ceramic green sheet for the insulating plate 2 using a conventionally known screen printing method. This is fired together with the ceramic green sheet for the insulating plate 2 to be attached to the outer peripheral portion of the upper surface of the insulating plate 2. By setting the firing shrinkage of the metallized paste for the dummy metallization layer 9 to be smaller than the firing shrinkage of the ceramic green sheet for the insulating plate 2, the difference in firing shrinkage between the two causes the center of the insulating plate 2. A swell is formed along the outer periphery of the closed space S such that the outer periphery of the dent rises. In the present invention, it is important that the swell is formed in the insulating plate 2 along the outer periphery of the closed space S. According to the pressure detecting device package of the present invention, since the undulation is formed along the outer periphery of the closed space S in the insulating plate 2, the amount of bending of the insulating plate 2 is increased by the undulation. Therefore, when pressure is applied to the insulating plate 2, the insulating plate 2 is largely bent according to the pressure, and a small change in pressure can be detected with high sensitivity. If the height of the undulation is less than 50 μm, it is difficult to greatly bend the insulating plate 2. Therefore, the height of the undulation is preferably 50 μm or more. The height of the undulation is determined by the difference between the shape and thickness of the dummy metallized layer 9 and the firing shrinkage of the metallized paste for the dummy metallized layer 9 and the firing shrinkage of the ceramic green sheet for the insulating plate 2. Can be controlled by changing. For example, when the insulating plate 2 is made of a 10 mm square, 0.3 mm thick aluminum oxide sintered body obtained by firing a ceramic green sheet having a firing shrinkage of 15%, and the diameter of the closed space S is 8 mm, the insulating plate 2 A dummy metallization layer 9 made of tungsten metallization having a diameter of 5 mm and a thickness of 15 to 20 μm is formed at the center on the upper surface, and the firing shrinkage rate of the metallization paste for the dummy metallization layer 9 is determined by using the ceramic green sheet If it is formed about 0.5 to 1.0% smaller than the firing shrinkage,
The height is 80 to 120 so that the center part is concave and the outer peripheral part rises
An undulation of about μm can be formed. in this case,
The greater the difference between the firing shrinkage of the metallization paste for the dummy metallization layer and the firing shrinkage of the ceramic green sheet for the insulating plate 2, the greater the undulation and the thicker the metallization layer 9 of the dummy. The higher the swell, the greater the swell. As described above, according to the pressure detecting device package of the present invention, the first electrode 7 for forming a capacitance is formed on the other main surface of the insulating base 1 on which the semiconductor element 3 is mounted on one main surface. And an insulating plate 2 having a second electrode 8 for forming a capacitance facing the first electrode 7 on the inner surface is formed so as to form a closed space S between the insulating plate 2 and the other main surface of the insulating base 1. Since the pressure sensitive element is joined to the insulating base 1 in a flexible state, the container for accommodating the semiconductor element 3 and the pressure sensitive element are integrated, and as a result, the pressure detecting device can be downsized. Further, the first electrode 7 and the second electrode 8 for forming the capacitance are
Since the semiconductor element 3 is connected to the semiconductor element 3 via the wiring conductors 5a and 5b provided on the insulating base 1, the first electrode 7 and the second electrode 8 can be connected to the semiconductor element 3 over a short distance. The unnecessary capacitance generated between the wiring conductors 5a and 5b can be reduced to provide a highly sensitive pressure detecting device. Thus, according to the above-described package for a pressure detecting device, the semiconductor element 3 is mounted on the mounting portion 1b, and each electrode of the semiconductor element 3 and the wiring conductor 5 are electrically connected. By sealing 3, a pressure detection device that is small and has high sensitivity is obtained. It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. In one example, the undulation was formed such that the central portion of the insulating plate 2 was concave and the outer peripheral portion was raised. However, as shown in the cross-sectional view of FIG. 2, the undulation was such that the central portion of the insulating plate 2 was raised and the outer peripheral portion was concave. May be formed. In this case, the firing shrinkage of the metallized paste for the dummy metallization layer 9 may be set to be larger than the firing shrinkage of the ceramic green c for the insulating plate 2. In the above-described embodiment, the dummy metallized layer 9 for undulation is provided on the outer peripheral portion of the upper surface of the insulating plate 2 so that the insulating plate 2
Although the undulation is formed, the undulation may be formed by, for example, pressing a ceramic green sheet for the insulating plate 2. Further, in an example of the above-described embodiment,
Although the insulating base 1 and the insulating plate 2 are joined by sintering and integration, the insulating base 1 and the insulating plate 2 may be joined by brazing. As described above, according to the pressure detecting device package of the present invention, the capacitance is formed on the other main surface of the insulating base on which the semiconductor element is mounted on one main surface. And an insulating plate having a capacitance-forming second electrode opposed to the first electrode is formed so as to form a closed space between the insulating plate and the other main surface of the insulating base. And the pressure-sensitive element are integrated with the container for accommodating the semiconductor element. As a result, the pressure detection device can be reduced in size and the wiring for connecting the pressure detection electrode and the semiconductor element. Can be reduced, and unnecessary capacitance generated between these wirings can be reduced. Further, since the undulation is formed along the outer periphery of the closed space in the insulating plate, the undulation tends to greatly deflect the insulating plate. Therefore, it is possible to provide a pressure detection device capable of detecting a small change in pressure satisfactorily.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of an embodiment of a package for a pressure detecting device according to the present invention. FIG. 2 is a cross-sectional view showing another example of the embodiment of the pressure detection device package according to the present invention. FIG. 3 is a sectional view showing a conventional pressure detecting device. [Description of Signs] 1 ... Insulating base 1b ... Mounting section 2 ... Insulating plate 3 ... Semiconductor element 5 ... Wiring conductor 7 ... First electrode 8 Second electrode 9 Dummy metallized layer S Sealed space

Claims (1)

Claims: 1. An insulating base having a mounting portion on one main surface on which a semiconductor element is mounted, and an electrode provided on the surface and inside of the insulating base, wherein each electrode of the semiconductor element is provided. Is electrically connected to the insulating base in a flexible state so as to form a substantially disk-shaped closed space between the plurality of wiring conductors electrically connected to each other and the other main surface of the insulating base. A first electrode for forming a capacitance, which is attached to the other main surface in the closed space and is electrically connected to one of the wiring conductors; A package for a pressure detection device, comprising: a second electrode for forming a capacitance, which is attached to a surface so as to face the first electrode and is electrically connected to another one of the wiring conductors. Wherein the insulating plate has undulations along the outer periphery of the closed space. Package for pressure detection device according to symptoms.