JP2002350264A - Package for pressure detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact and highly sensitive pressure detector capable of always accurately detecting an external pressure. SOLUTION: This package for the presser detector is provided with an insulated base body 1 for mounting a semiconductor element 3 on one main face, a plurality of wiring conductors 5 arranged in the insulated base body 1 for electrically connecting respective electrodes of the semiconductor element 3, an insulating board 2 connected to the insulated base body 1 flexibly for forming a sealed space between the other main face of the insulated base body 1 and itself, an electrostatic capacity formation first electrode 8 installed to the other main face of the insulated base body 1 and electrically connected to one conductor 5a in the wiring conductors 5, and an electrostatic capacity formation second electrode 9 installed on the inside main face of the insulating board 2 and electrically connected to the other conductor 5b of the wiring conductors 5. An electrostatic capacity value formed between the first electrode 8, the second electrode 9, and an earth conductor 6 is 50% or less of that formed between the first electrode 8 and the second electrode 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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.

[0002]

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. 2, 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 accommodated 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 with
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 in response to an external pressure. The capacitance formed between the forming electrodes 23 and 25 changes. An external pressure can be detected by subjecting the change in capacitance to arithmetic processing by the arithmetic semiconductor element 29.

[0003]

However, according to the 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 detecting device and the pressure detecting 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 one main surface on which a semiconductor element is mounted; and a plurality of wiring conductors disposed on and inside the insulating base and electrically connected to respective electrodes of the semiconductor element. A first electrode for forming a capacitance, which is attached to the center 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. A pressure detection device package including a second electrode for forming a capacitance electrically connected to another one has been proposed.

According to the 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 a first electrode for forming a capacitance opposing the first electrode is provided. Since the insulating plate having the two electrodes on the inner surface is joined in a flexible state so as to form a closed space between the insulating plate and the other main surface of the insulating base, the pressure-sensitive package is accommodated in the package containing the semiconductor element. The elements are formed integrally, which makes it possible to reduce the size of the pressure detecting device and to shorten the wiring connecting the electrode for pressure detection and the semiconductor element, thereby reducing unnecessary static electricity generated between these wirings. The capacity can be reduced.

In such a package for a pressure detecting device, a ground conductor for supplying a ground potential to the semiconductor element is provided on the insulating base.

However, according to the pressure detecting device package proposed in Japanese Patent Application No. 2000-178618, the capacitance formed between the ground conductor and the first and second electrodes is not considered. Unnecessary capacitance is formed large between the ground conductor and the first and second electrodes, which causes a problem that the pressure detection sensitivity is reduced.

The present invention has been completed in view of the above-mentioned problems, and an object of the present invention is to provide a pressure detecting device which is small, has high sensitivity, and can accurately detect an external pressure. It is in.

[0009]

A package for a pressure detecting device according to the present invention has an insulating base having a mounting portion on one of its main surfaces on which a semiconductor element is mounted, and an electrode provided on the insulating base for mounting the semiconductor element. A plurality of wiring conductors and a ground conductor electrically connected to each other, and an insulating plate joined to the insulating base in a flexible state so as to form a sealed space between 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, and faces the first electrode on the inner main surface of the insulating plate. And a second electrode for forming a capacitance electrically attached to another one of the wiring conductors. The capacitance value formed between the electrode and the ground conductor is between the first electrode and the second electrode. It is characterized in that made the more than 50% of the capacitance value.

According to the pressure detection device package of the present invention, the capacitance value formed between the first electrode and the second electrode and the ground electrode is formed between the first electrode and the second electrode. Since the capacitance value is 50% or less of the capacitance value, the capacitance formed between the first electrode and the second electrode and the ground electrode does not significantly lower the pressure detection sensitivity.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 pressure detection device package 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 nitride-based sintered body having a concave portion 1a for accommodating therein and a substantially circular concave portion 1c for forming a substantially disk-shaped closed space between the upper surface and an insulating plate 2 described later. A laminate made of a ceramic material such as an aluminum sintered body, a mullite sintered body, or a glass-ceramic. For example, in the case of an aluminum oxide sintered body, aluminum oxide, silicon oxide, magnesium oxide, oxide An appropriate organic binder, a solvent, a plasticizer, and a dispersant are added to a ceramic raw material powder such as calcium and mixed to form a slurry, which is formed into a sheet by employing a well-known doctor blade method. Ceramic green sheets, and then these ceramic green sheets are properly punched, laminated and cut. It is manufactured by firing at a temperature of about 1600 ° C. with a ceramic green sheet for the insulating plate 2 with obtaining raw ceramic formed body later this green ceramic body insulating substrate 1 by performing.

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, and the semiconductor element 3 is mounted on the mounting portion 1b.
And the semiconductor element 3 is sealed by filling the recess 1a with a resin sealing material 4 such as an epoxy resin. In this example, the semiconductor element 3 is sealed by filling a resin sealing material 4 into the concave portion 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 concave portion 1a. It may be sealed by joining so as to close.

A plurality of wiring conductors 5 and ground conductors 6 to which electrodes of the semiconductor element 3 are connected are led out from the mounting portion 1b. The semiconductor element 3 is placed on the ground conductor 6 via a conductive bonding material. Joining, wiring conductor 5 and ground conductor 6
And the respective electrodes of the semiconductor element 3 are connected via electrical connection means such as bonding wires 7 so that the semiconductor element 3
Are electrically connected to the respective wiring conductors 5 and the ground conductor 6. In this example, the electrodes of the semiconductor element 3 are connected to the wiring conductors 5 and the grounding conductors 6 by bonding wires 7.
However, the electrodes of the semiconductor element 3 may be connected to the wiring conductor 5 and the ground conductor 6 by another kind of electrical connection means such as a solder bump.

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 8 and a second electrode 9, which will be described later. 1 and the other part is the first electrode 8
-It is electrically connected to the second electrode 9. The ground conductor 6 supplies a ground potential to the semiconductor element 3 and functions as a base metal for fixing the semiconductor element 3 to the mounting portion 1b. The ground conductor 6 is formed from the mounting portion 1b to the outer peripheral portion of the lower surface of the insulating base 1. I have. Then, the semiconductor element 3 is bonded to the ground conductor 6 via a conductive bonding material such as a gold-silicon alloy, and each electrode of the semiconductor element 3 is electrically connected to the wiring conductor 5 and the ground conductor 6 by a bonding wire 7 or the like. , The semiconductor element 3 is sealed with a resin sealing material 4, and then the wiring conductor 5 and the ground conductor 6 are sealed.
The semiconductor element 3 housed inside is electrically connected to the external electric circuit by joining the portion led out to the lower surface of the outer periphery of the insulating base 1 to the wiring conductor of the external electric circuit board via a conductive bonding material such as solder. Will be done.

Such a wiring conductor 5 and a ground conductor 6
Consists of metallized metal powders such as tungsten, molybdenum, copper, silver, and the like. By applying a printing method to a ceramic green sheet for the insulating substrate 1 in a predetermined pattern by printing, and firing this together with the green ceramic molded body for the insulating substrate 1, a predetermined pattern is formed inside and on the surface of the insulating substrate 1. Is formed.
The exposed surfaces of the wiring conductor 5 and the grounding conductor 6 are prevented from being oxidized and corroded by the wiring conductor 5 and the grounding conductor 6, and are bonded to the bonding wire 7 and the conductive bonding material. In order to obtain a good value, normally, a nickel plating layer having a thickness of about 1 to 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are sequentially applied.

A first electrode 8 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 8 is for forming a capacitance for a pressure-sensitive element together with a second electrode 9 of the insulating plate 2 described later. The first electrode 8 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 7, the electrode of the semiconductor element 3 and the first electrode 8 are electrically connected. The connection is made.

The first electrode 8 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 the 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.

A substantially flat insulating plate 2 covering the recess 1c is formed on the upper surface of the insulating substrate 1 so as to form a substantially disc-shaped closed space between the insulating substrate 1 and the upper surface of the insulating substrate 1. And is sintered and integrated with the insulating base 1 and joined. Insulating plate 2
Is a flat plate of about 0.01 to 5 mm in thickness of approximately square or approximately octagonal or circular made of a ceramic material such as aluminum oxide sintered body, aluminum nitride sintered body, mullite sintered body, glass-ceramics, It functions as a so-called pressure detecting diaphragm that bends toward the insulating base 1 in response to external pressure.

If the insulating plate 2 is made of, for example, an aluminum oxide sintered body, an organic binder, a solvent, and a plastic material suitable for 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 shape 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.

If the thickness of the insulating plate 2 is less than 0.01 mm, the mechanical strength of the insulating plate 2 becomes small, so that there is a great risk that the insulating plate 2 will be broken when a large external pressure is applied thereto. On the other hand, if it exceeds 5 mm, it becomes difficult to bend under a small pressure, and it becomes unsuitable as a diaphragm for pressure detection. Therefore, the thickness of the insulating plate 2 is preferably in the range of 0.01 to 5 mm.

A substantially circular second electrode 9 for forming a capacitance is attached to the lower surface of the insulating plate 2 so as to face the first electrode 8. The second electrode 9 functions as an electrode for forming a capacitance for the pressure-sensitive element together with the first electrode 8 described above. The other one 5b of the wiring conductor 5 is connected to the second electrode 9, so that the wiring conductor 5
When the electrode of the semiconductor element 3 is connected to the electrode b via an electrical connection means such as a bonding wire 7, the electrode of the semiconductor element 3 and the second electrode 9 are electrically connected.

At this time, the first electrode 8 and the second electrode 9
They face each other with a closed space formed between the insulating base 1 and the insulating plate 2 therebetween, between which the areas of the first electrode 8 and the second electrode 9 and the first electrode 8 and the second electrode A predetermined capacitance is formed in accordance with the distance from the capacitor 9. And the insulating plate 2
When an external pressure is applied to the upper surface of the first electrode 8, the insulating plate 2 bends toward the insulating base 1 in accordance with the external pressure, and the distance between the first electrode 8 and the second electrode 9 changes. Since the capacitance between the second electrode 9 and the second electrode 9 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 housed in the recess 1a via the wiring conductors 5a and 5b,
The magnitude of the external pressure can be known by performing an arithmetic process on this in the semiconductor element 3.

The second electrode 9 is made of a metallized metal powder such as tungsten, molybdenum, copper, silver or the like, and is obtained by adding a suitable organic binder, solvent, plasticizer and dispersant to a metal powder such as tungsten. The metallized paste is applied by printing to a 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 8 is formed on the lower surface of the insulating plate 2.

In the present invention, the capacitance value formed between the first electrode 8 and the second electrode 9 and the ground conductor 6 is formed between the first electrode 8 and the second electrode 9. It is less than 50% of the capacitance value, which is important. As described above, the capacitance value formed between the first electrode 8 and the second electrode 9 and the ground conductor 6 is equal to the capacitance value formed between the first electrode 8 and the second electrode 9. Since it is 50% or less, the capacitance formed between the first electrode 8 and the second electrode 9 and the ground conductor 6 does not significantly lower the pressure detection sensitivity. It can be detected well.

The capacitance value formed between the first electrode 8 and the second electrode 9 and the ground conductor 6 is equal to the capacitance value formed between the first electrode 8 and the second electrode 9. Exceeds 50%, the capacitance formed between the first electrode 8 and the second electrode 9 and the ground conductor 6 greatly reduces the pressure detection sensitivity. Therefore, the capacitance value formed between the first electrode 8 and the second electrode 9 and the ground conductor 6 is 50 times the capacitance value formed between the first electrode 8 and the second electrode 9. % Or less.

The capacitance value formed between the first electrode 8 and the second electrode 9 and the ground conductor 6 is changed to the capacitance value formed between the first electrode 8 and the second electrode 9. In order to make it 50% or less, the overlapping area between the first electrode 8 and the second electrode 9 and the ground conductor 6 is reduced, and the distance between the first electrode 8 and the second electrode 9 and the ground conductor 6 is increased. Alternatively, the dielectric constant of the insulating base 1 may be reduced.

As described above, according to the pressure detecting device package of the present invention, the first electrode 8 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 an inner surface on which an electrostatic capacity forming second electrode 9 facing the first electrode 8 forms an enclosed space between the insulating plate 2 and the other main surface of the insulating base 1. Since it is joined to the insulating base 1 in a flexible state, the container accommodating the semiconductor element 3 and the pressure-sensitive element are integrated, and as a result, the pressure detecting device can be downsized. Also,
Since the first electrode 8 and the second electrode 9 for forming the capacitance are connected to the semiconductor element 3 via the wiring conductors 5a and 5b provided on the insulating base 1, the first electrode 8 and the second electrode 9 are connected.
Can be connected to the semiconductor element 3 over a short distance, and unnecessary capacitance generated between these wiring conductors 5a and 5b can be reduced to provide a highly sensitive pressure detection 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 is electrically connected to the wiring conductor 5 and the ground conductor 6. Thereafter, by sealing the semiconductor element 3, a compact and high-sensitivity pressure detection device capable of accurately detecting an external pressure 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 insulating base 1 and the insulating plate 2 are joined by sintering and integration, but the insulating base 1 and the insulating plate 2 may be joined by brazing.

[0031]

As described above, according to the pressure detecting device package of the present invention, the first main surface of the insulating base on which the semiconductor element is mounted is provided with the second main surface for forming the capacitance. Along with providing one electrode, an insulating plate having a second electrode for capacitance formation facing the first electrode is formed in a flexible state so as to form a closed space between the insulating plate and the other main surface of the insulating base. Because of the joining, the container accommodating the semiconductor element and the pressure-sensitive element are integrated, and as a result, the pressure detection device can be reduced in size. Further, since the capacitance value formed between the first electrode and the second electrode and the ground electrode is 50% or less of the capacitance value formed between the first electrode and the second electrode, The capacitance formed between the first electrode and the second electrode and the ground electrode does not significantly reduce the pressure detection sensitivity, and as a result, it is possible to accurately and sensitively detect the external pressure. A possible pressure sensing device can be provided.

[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 a conventional pressure detecting device.

[Explanation of symbols]

 1 ... insulating base 1 b ... mounting part 2 ... insulating plate 3 ... semiconductor element 5 ... wiring conductor 6 ... ground conductor 8 ... ... first electrode 9 ... second electrode

Claims (1)

[Claims] An insulating base having a mounting portion on one main surface on which a semiconductor element is mounted, a plurality of wiring conductors disposed on the insulating base and electrically connected to electrodes of the semiconductor element, and a ground. An insulating plate joined to the insulating base in a flexible state so as to form a sealed space between the conductor and the other main surface of the insulating base; and an insulating plate covering the other main surface in the sealed space. A first electrode for forming a capacitance, which is electrically connected to one of the wiring conductors, and is attached to an inner main surface of the insulating plate so as to face the first electrode; A package for a pressure detecting device comprising: a second electrode for forming a capacitance electrically connected to another one of the conductors, wherein the first electrode, the second electrode, and the ground conductor Is formed between the first electrode and the second electrode. A package for a pressure detection device, wherein the package has a capacitance value of 50% or less.