JP2002323393A - Package for pressure detector - Google Patents

Abstract

(57) [Problem] To provide a small and highly sensitive pressure detecting device capable of always and accurately detecting external pressure over a long period of time. SOLUTION: A first metallized electrode 7 for forming a capacitance is provided on the other main surface of a ceramic substrate 1 on which a semiconductor element 3 is mounted on one main surface, and a static electrode facing the first metallized electrode 7 is provided. A ceramic plate 2 having a second metallized electrode 9 for forming a capacitance on the inner main surface and having a reinforcing metallized layer 11 on almost the entire outer main surface excluding a region corresponding to the second metallized electrode 9 is prepared. This is a package for a pressure detecting device which is joined in a flexible state so as to form a closed space between the pressure detecting device and the ceramic base 1.

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. 2000-223.
787, a ceramic base having a mounting portion on one main surface on which a semiconductor element is mounted, and a plurality of metallized wirings disposed on and inside the ceramic base and electrically connected to respective electrodes of the semiconductor element A conductor, a first metallized electrode for forming a capacitance, which is attached to a central portion of the other main surface of the ceramic base and is electrically connected to one of the metallized wiring conductors; and the other main surface of the ceramic base To
A ceramic plate joined in a flexible state so as to form a sealed space with the central portion of the main surface; and a metallized plate attached to the inner main surface of the ceramic plate so as to face the first metallized electrode. A pressure detecting device comprising: a second metallized electrode for forming a capacitance electrically connected to another one of the wiring conductors; and a reinforcing metallized layer applied to substantially the entire outer main surface of the ceramic plate. Suggested package.

According to the pressure detecting device package,
A first metallization electrode for forming a capacitance is provided on the other main surface of a ceramic substrate having a mounting portion on which a semiconductor element is mounted on one main surface, and a first metallization electrode for forming a capacitance opposing the first metallization electrode is provided. The ceramic plate having the second metallized electrode on the inner main surface is joined in a flexible state so as to form a sealed space between the ceramic plate and the other main surface of the ceramic base, so that the semiconductor element is accommodated. The pressure-sensitive element is formed integrally with the package, and as a result, the pressure detecting device can be reduced in size, and the wiring for connecting the electrode for pressure detection and the semiconductor element is shortened. Unnecessary capacitance can be reduced. In addition, since the metallizing layer for reinforcement is applied to substantially the entire outer main surface of the ceramic plate, cracks may occur in the outer peripheral portion of the ceramic plate when external pressure is repeatedly applied to the ceramic plate. Is effectively prevented, and even if a crack occurs, the crack is effectively prevented from progressing to the center of the ceramic plate.

However, according to the pressure detecting device package proposed in Japanese Patent Application No. 2000-223787, since the reinforcing metallization layer is applied to almost the entire outer main surface of the ceramic plate, the ceramic metallization layer is applied. The layer makes it difficult to bend, and the coefficient of thermal expansion of the portion of the ceramic plate corresponding to the second metallized electrode is significantly different from the coefficient of thermal expansion of the ceramic base. There was a problem that the pressure detection characteristics changed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the size and sensitivity of a ceramic plate so that it is easy to bend and the pressure detection characteristics hardly change due to temperature changes. Moreover, it is an object of the present invention to provide a pressure detecting device capable of accurately detecting an external pressure.

[0008]

A package for a pressure detecting device according to the present invention is provided on a ceramic substrate having a mounting portion on one side of which a semiconductor element is mounted, and disposed on and inside the ceramic substrate. A ceramic plate joined to a ceramic base in a flexible state so as to form a sealed space between a plurality of metallized wiring conductors to which each electrode of a semiconductor element is electrically connected and the other main surface of the ceramic base. And a first metallized electrode for forming a capacitance, which is attached to the other main surface of the ceramic base in the enclosed space and is electrically connected to one of the metallized wiring conductors, and A pressure sensing device comprising: a second metallized electrode for forming a capacitance, which is attached to face the first metallized electrode and is electrically connected to another one of the metallized wiring conductors In the mounting package, the ceramic plate is characterized in that a metallizing metal layer for reinforcement is formed on substantially the entire surface of the outer main surface except for a region corresponding to the second metallized electrode. is there.

According to the pressure detecting device package of the present invention, the first metallized electrode for forming the capacitance is provided on the other main surface of the ceramic base having the mounting portion on which the semiconductor element is mounted on one main surface. In addition, the ceramic plate having an inner surface on which a second metallized electrode for forming a capacitance facing the first metallized electrode is formed so as to form a closed space between the ceramic plate and the other main surface of the ceramic substrate. The pressure sensitive element is formed integrally with the package that contains the semiconductor element, and as a result, the pressure detection device can be made smaller and the pressure detecting electrode and the semiconductor element are connected. By reducing the length of the wiring, unnecessary capacitance generated between these wirings can be reduced. Furthermore, since a reinforcing metallization layer is applied to almost the entire surface of the outer main surface of the ceramic plate except for a region corresponding to the second metallized electrode, when external pressure is repeatedly applied to the ceramic plate, the ceramic is Cracks are effectively prevented from occurring in the outer peripheral portion of the plate, and even if cracks occur, the cracks are effectively prevented from progressing to the center of the ceramic plate. In addition, since the reinforcing metallization layer is applied to substantially the entire surface of the ceramic plate except for a region corresponding to the second metallized electrode on the outer main surface, the ceramic plate is easily bent and the second metallized electrode on the ceramic plate is easily formed. Does not greatly differ from the thermal expansion coefficient of the ceramic substrate.

[0010]

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 a ceramic base, 2 is a ceramic plate, 3 is a semiconductor element.

The ceramic substrate 1 is a laminated body made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a glass-ceramic. If this is the case, a suitable organic binder, a solvent, a plasticizer, and a dispersant are added to a ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide to form a slurry, which is conventionally known. A plurality of ceramic green sheets are obtained by forming into a sheet shape by employing a doctor blade method, and then these ceramic green sheets are subjected to appropriate punching, laminating, and cutting to obtain a ceramic green sheet. And a green ceramic compact of about 1600 ° C. It is manufactured by firing at a temperature.

The ceramic substrate 1 has a concave portion 1a for accommodating the semiconductor element 3 in the center of the lower surface thereof, and thereby functions as a container for accommodating the semiconductor element 3. The center of the bottom surface of the concave portion 1a is a mounting portion 1b on which the semiconductor element 3 is mounted.
The semiconductor element 3 is sealed by mounting the semiconductor element 3 on the substrate b and 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 recess 1a, but the semiconductor element 3 is provided with a lid made of metal or ceramic on the lower surface of the ceramic base 1 in the recess 1a. It may be sealed by joining so as to close.

A plurality of metallized wiring conductors 5 connected to the respective electrodes of the semiconductor element 3 are led out from the mounting portion 1b. The metallized wiring conductor 5 and the respective electrodes of the semiconductor element 3 are connected to the solder bumps 6 and the like. By bonding via a conductive bonding material made of a conductive material, each electrode of the semiconductor element 3 and each metallized wiring conductor 5 are electrically connected, and the semiconductor element 3 is fixed to the mounting portion 1b. In this example, the electrodes of the semiconductor element 3 and the metallized wiring conductors 5 are connected via the solder bumps 6, but the electrodes of the semiconductor element 3 and the metallized wiring conductors 5 are connected to another type of electric wire such as a bonding wire. May be connected by a dynamic connection means.

The metallized 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 metallized electrode 7 and a second metallized electrode 9 to be described later. Is led out to the lower surface of the outer periphery of the ceramic base 1, and another part is electrically connected to the first metallized electrode 7 and the second metallized electrode 9. The electrodes of the semiconductor element 3 are electrically connected to the metallized wiring conductors 5 via the solder bumps 6 and the semiconductor element 3 is sealed with a resin sealing material 4. 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 base 1 to the wiring conductor of the external electric circuit board via a conductive bonding material such as solder. It will be.

Such a metallized wiring conductor 5 is made of metallized metal powder such as tungsten, molybdenum, copper, silver or the like, and is mixed with a metal powder such as tungsten by adding an appropriate organic binder, solvent, plasticizer, dispersant or the like. The metallized paste thus obtained is applied in a predetermined pattern to a ceramic green sheet for the ceramic substrate 1 by employing a conventionally known screen printing method, and is fired together with the green ceramic molded body for the ceramic substrate 1 to obtain a ceramic. A predetermined pattern is formed inside and on the surface of the base 1. In addition, in order to prevent the metallized wiring conductor 5 from being oxidized and corroded and to make the metallized wiring conductor 5 and a conductive bonding material such as solder good, the exposed surface of the metallized wiring conductor 5 is usually formed on the exposed surface. If so, the nickel plating layer having a thickness of about 1 to 10 μm and the thickness of 0.1 to
A gold plating layer of about 3 μm is sequentially applied.

A frame-like projection 1c having a height of about 0.01 to 5 mm is provided on the outer peripheral portion of the upper surface of the ceramic base 1, whereby a substantially circular concave portion 1d having a substantially flat bottom surface is provided at the center of the upper surface. Is formed. The concave portion 1d is for forming a closed space between the concave portion 1d and the ceramic plate 2, and a first metallized electrode 7 for forming a capacitance is attached to the bottom surface of the concave portion 1d. ing.

The first metallized electrode 7 is for forming a capacitance for a pressure-sensitive element together with a second metallized electrode 9 to be described later, and is formed, for example, in a substantially circular pattern. One of the metallized wiring conductors 5a is connected to the first metallized electrode 7 so that the electrode of the semiconductor element 3 is connected to the metallized wiring conductor 5a via a conductive bonding material such as a solder bump 6. When connected, the electrode of the semiconductor element 3 and the first metallized electrode 7 are electrically connected.

The first metallized electrode 7 is made of metallized metal powder such as tungsten, molybdenum, copper, silver or the like. An appropriate organic binder, solvent, plasticizer and dispersant are added to metal powder such as tungsten and mixed. The metallized paste thus obtained is printed and applied to a ceramic green sheet for the ceramic substrate 1 by employing a conventionally known screen printing method, and is fired together with the green ceramic molded body for the ceramic substrate 1 to thereby form recesses in the ceramic substrate 1. A predetermined pattern is formed on the bottom surface of 1d. In addition, in order to prevent the first metallized electrode 7 from being oxidized and corroded, the exposed surface of the first metallized electrode 7 is usually
A nickel plating layer having a thickness of about 1 to 10 μm is applied.

On the upper surface of the projection 1c of the ceramic base 1, a frame-shaped first bonding metallization layer 8 is attached over the entire periphery thereof. The ceramic plate 2 having the second bonding metallization layer 10 is bonded via a conductive bonding material such as a silver-copper brazing material.

One of the metallized wiring conductors 5b is connected to the first bonding metallized layer 8, so that the electrodes of the semiconductor element 3 are connected to the metallized wiring conductor 5b by a conductive bonding material such as a solder bump 6. And the second metallized electrode 9 and the electrode of the semiconductor element 3 are electrically connected via the metallized wiring conductor 5b, the first metallized layer 8 for bonding and the metallized layer 10 for second bonding. It has become.

The first bonding metallization layer 8 is made of metal powder metallization such as tungsten, molybdenum, copper, silver or the like.
A metallized paste obtained by adding and mixing a solvent, a plasticizer and a dispersant is printed and applied to a ceramic green sheet for the ceramic substrate 1 by employing a conventionally known screen printing method, and this is formed into a green ceramic for the ceramic substrate 1. By firing together with the body, a predetermined frame-shaped pattern is formed on the upper surface of the protrusion 1c of the ceramic base 1. In addition,
On the surface of the first bonding metallization layer 8, the first bonding metallization layer 8 is prevented from being oxidized and corroded, and the bonding between the first bonding metallization layer 8 and the conductive bonding material is strengthened. Usually, a nickel plating layer having a thickness of about 1 to 10 μm is applied.

The ceramic plate 2 attached to the upper surface of the ceramic base 1 has a thickness made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, or a glass-ceramic. Is 0.01 ~
It is a substantially flat plate of 5 mm, and functions as a so-called pressure detecting diaphragm that bends toward the ceramic base 1 according to an external pressure.

The ceramic plate 2 has a thickness of 0.01
If it is less than 5 mm, its mechanical strength will be small, so that when a large external pressure is applied thereto, there is a great risk of being destroyed.
If it exceeds m, it becomes difficult to bend under a small pressure, and it is unsuitable as a diaphragm for pressure detection. Therefore, the thickness of the ceramic plate 2 is preferably in the range of 0.01 to 5 mm.

When such a ceramic plate 2 is made of, for example, an aluminum oxide sintered body, an organic binder, a solvent, and a plastic suitable for ceramic raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. A ceramic green sheet is obtained by adding and mixing an agent and a dispersing agent to form a slurry and forming this into a sheet by employing a conventionally known doctor blade method.
Thereafter, the ceramic green sheet is subjected to appropriate punching and cutting to obtain a green ceramic molded body for the ceramic plate 2 and to fire the green ceramic molded body at a temperature of about 1600 ° C. .

In the center of the lower surface of the ceramic plate 2,
A substantially circular second metallized electrode 9 for forming a capacitance is provided. The second metallized electrode 9 functions as an electrode for forming a capacitance for a pressure-sensitive element together with the first metallized electrode 7 described above.

The second metallized electrode 9 is made of metal powder such as tungsten, molybdenum, copper, silver or the like, and is mixed with a metal powder such as tungsten by adding an appropriate organic binder, solvent, plasticizer and dispersant. The metallized paste thus obtained is printed and applied to a ceramic green sheet for the ceramic plate 2 by employing a conventionally well-known screen printing method, and is fired together with a green ceramic molded body for the ceramic plate 2 to thereby obtain a lower surface of the ceramic plate 2. Is formed in a predetermined pattern at the center of the. In addition, in order to prevent the second metallized electrode 9 from being oxidized and corroded, a nickel plating layer having a thickness of about 1 to 10 μm is usually applied to the exposed surface of the second metallized electrode 9. .

Further, a frame-shaped second bonding metallization layer 10 electrically connected to the second metallization electrode 9 is attached to the outer peripheral portion of the lower surface of the ceramic plate 2. This second metallization layer 10 for bonding functions as a bonding base metal layer for bonding the ceramic plate 2 to the ceramic base 1,
First bonding metallization layer 8 and second bonding metallization layer 10
Are joined via a conductive joining material such as silver-copper brazing, so that the ceramic plate 2 is joined to the ceramic base 1 and the metallized wiring conductor 5b and the second metallized electrode 9 are electrically connected.

Such a second bonding metallization layer 10 is
A metallized paste made of metal powder such as tungsten, molybdenum, copper, silver, etc., and mixed with a metal powder such as tungsten by adding an appropriate organic binder, solvent, plasticizer, and dispersant. The ceramic green sheet for the ceramic plate 2 is adopted and printed, and is fired together with the green ceramic molded body for the ceramic plate 2 to form a predetermined pattern on the outer peripheral portion of the lower surface of the ceramic plate 2. In addition, on the surface of the second bonding metallization layer 10, to prevent the second bonding metallization layer 10 from being oxidized and corroded, and to improve the bonding between the second bonding metallization layer 10 and the conductive bonding material. Usually, a nickel plating layer having a thickness of about 1 to 10 μm is applied.

At this time, the first metallized electrode 7 and the second metallized electrode 9 face each other with a space formed between the ceramic base 1 and the ceramic plate 2 therebetween. A predetermined capacitance is formed according to the area of one metallized electrode 7 or the second metallized electrode 9 and the distance between the first metallized electrode 7 and the second metallized electrode 9. When an external pressure is applied to the upper surface of the ceramic plate 2, the ceramic plate 2 bends toward the ceramic base 1 according to the pressure, and the distance between the first metallized electrode 7 and the second metallized electrode 9 changes, As a result, the capacitance between the first metallized electrode 7 and the second metallized electrode 9 changes, so that it functions as a pressure-sensitive element that senses a change in external pressure as a change in capacitance. Then, the change of the capacitance is transmitted to the semiconductor element 3 housed in the recess 1a via the metallized wiring conductors 5a and 5b, and the magnitude of the external pressure is known by performing arithmetic processing on the semiconductor element 3. be able to.

As described above, according to the pressure detecting device package of the present invention, the first metallization for forming the capacitance is formed on the other main surface of the ceramic substrate 1 on which the semiconductor element 3 is mounted on one main surface. An electrode 7 is provided, and a ceramic plate 2 having a second metallized electrode 9 for forming a capacitance facing the first metallized electrode 7 on an inner main surface is formed so as to form a closed space between the ceramic plate 2 and the ceramic substrate 1. Since they are joined in a flexible state, the container for accommodating the semiconductor element 3 and the pressure-sensitive element are integrated, and as a result, the size of the pressure detection device can be reduced. Since the first metallized electrode 7 and the second metallized electrode 9 for forming the capacitance are connected to the semiconductor element 3 via the metallized wiring conductors 5a and 5b provided on the ceramic base 1, the first metallized electrode 7 And the second metallized electrode 9 can be connected to the semiconductor element 3 at a short distance, and as a result, unnecessary capacitance generated between these metallized wiring conductors 5a and 5b is reduced, and a highly sensitive pressure detecting device is provided. Can be provided.

When the distance between the first metallized electrode 7 and the second metallized electrode 9 is less than 0.01 mm at 1 atm, when a large pressure is applied to the ceramic plate 2,
There is a danger that the first metallized electrode 7 and the second metallized electrode 9 may come into contact with each other and the pressure cannot be detected. The capacitance formed between them tends to be small, and the sensitivity for detecting pressure tends to be low. Therefore, the distance between the first metallized electrode 7 and the second metallized electrode 9 is 0.
A range of 01 to 5 mm is preferred.

Further, on the upper surface of the ceramic plate 2,
A metallization layer 11 for reinforcement is provided on substantially the entire surface except for a region corresponding to the second metallization electrode 9. The reinforcing metallization layer 11 is made of metal powder of metal such as tungsten, molybdenum, copper, silver, etc., and prevents the occurrence of cracks in the outer peripheral portion of the ceramic plate 2 when external pressure is repeatedly applied to the ceramic plate 2. It functions as a barrier for preventing the crack from advancing to the center of the ceramic plate 2 even if the crack occurs. As described above, according to the pressure detecting device package of the present invention, the reinforcing metallized layer 11 is applied to substantially the entire outer surface of the ceramic plate 2 except for the region corresponding to the second metallized electrode 9. Accordingly, even when external pressure is repeatedly applied to the ceramic plate 2, cracks are effectively prevented from being generated on the outer peripheral portion of the ceramic plate 2, and even if cracks are generated, the cracks are not generated. Proceeding to the center of the ceramic plate 2 is effectively prevented. Also, metallization layer 11 for reinforcement
Is attached to substantially the entire outer surface of the ceramic plate 2 except for a region corresponding to the second metallized electrode 9, so that the ceramic plate 2 is not largely prevented from bending, and the ceramic plate 2 is not bent. The coefficient of thermal expansion of the portion corresponding to the second metallized electrode 9 does not greatly differ from the coefficient of thermal expansion of the ceramic substrate 1. Therefore, according to the pressure detecting device package of the present invention, the ceramic plate 2 is easily bent and the pressure detecting characteristics hardly change due to a temperature change. Therefore, the size is small, the sensitivity is high, and the external pressure is accurately detected. A pressure detecting device capable of performing the above-described operations.

When the thickness of the reinforcing metallization layer 11 is less than 5 μm, when an external pressure is repeatedly applied to the ceramic plate 2, cracks are generated on the outer peripheral portion of the ceramic plate 2 and the cracks are generated. When it exceeds 50 μm, the risk of not being able to effectively prevent the metal from proceeding to the center of the ceramic plate 2 is increased.
Due to the difference in the thermal expansion coefficient between the ceramic plate 2 and the reinforcing metallized layer 11, the risk of the reinforcing metallized layer 11 peeling off from the ceramic plate 2 increases. Therefore, the thickness of the reinforcing metallization layer 11 is preferably in the range of 5 to 50 μm.

The metallizing paste 11 obtained by adding a suitable organic binder, a solvent, a plasticizer and a dispersant to a metal powder such as tungsten and mixing the metallized paste by a conventionally known screen printing method. Ceramic plate 2
A ceramic green sheet for printing is applied and printed, and is fired together with the green ceramic molded body for the ceramic plate 2 to form a predetermined pattern on substantially the entire surface of the upper surface of the ceramic plate 2 except for the region corresponding to the second metallized electrode 9. Is done. Also, on the exposed surface of the reinforcing metallization layer 11,
In order to prevent the reinforcing metallization layer 11 from being oxidized and corroded, 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 usually applied.

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 metallized wiring conductor 5 are electrically connected. By sealing the element 3, a highly reliable pressure detecting device which is small in size, has high sensitivity, and can accurately detect external pressure over a long period of time is provided.

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. For example, in one example of the above-described embodiment, the ceramic base 1 and the ceramic plate 2 are joined by a conductive joining material such as silver-copper brazing.
The ceramic base 1 and the ceramic plate 2 may be joined by being sintered and integrated with each other. in this case,
There is no need to provide the first bonding metallization layer 8 and the second bonding metallization layer 10.

[0037]

As described above, according to the pressure detecting device package of the present invention, the capacitance is provided on the other main surface of the ceramic base having the mounting portion on which the semiconductor element is mounted on one main surface. A first metallized electrode for formation is provided, and a ceramic plate having a second metallized electrode for capacitance formation facing the first metallized electrode on the inner surface is hermetically sealed with the other main surface of the ceramic base. Since the bonding is performed in a flexible state so as to form a space, the package accommodating the semiconductor element and the pressure-sensitive element are integrated, and as a result, the pressure detecting device can be downsized. In addition, since the first metallized electrode and the second metallized electrode for forming the capacitance are connected to the semiconductor element via the metallized wiring conductor provided on the insulating base, the first metallized electrode and the second metallized electrode can be short distances. As a result, it is possible to provide a pressure sensitive device with high sensitivity by reducing unnecessary capacitance generated between these metallized wiring conductors. Furthermore, since the reinforcing metallization layer is applied to substantially the entire surface of the outer main surface of the ceramic plate except for the region corresponding to the second metallization electrode, even when external pressure is repeatedly applied to the ceramic plate. In addition, it is possible to effectively prevent the occurrence of cracks on the outer peripheral portion of the ceramic plate, and even if cracks occur, the cracks are effectively prevented from progressing to the center of the ceramic plate. It is possible to provide a pressure detecting device capable of accurately detecting an external pressure for a long period without reducing the airtightness of a sealed space formed between a ceramic substrate and a ceramic plate. Furthermore, since the metallization layer for reinforcement is applied to substantially the entire surface of the outer main surface of the ceramic plate except for the region corresponding to the second electrode, the metal plate does not significantly hinder the bending of the ceramic plate. The coefficient of thermal expansion of the portion corresponding to the second metallized electrode in the ceramic plate does not greatly differ from the coefficient of thermal expansion of the ceramic base, so that the ceramic plate is easily bent and the pressure detection characteristics hardly change due to a temperature change. Thus, it is possible to provide a pressure detecting device capable of always accurately detecting an external pressure.

[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 Ceramic substrate 2 Ceramic plate 3 Semiconductor element 5, 5a, 5b Metallized wiring conductor 7 First metallized electrode 9 ... Second metallized electrode 11 ... Reinforcing metallized layer

Claims (1)

[Claims] 1. A ceramic base having a mounting portion on one side of which a semiconductor element is mounted, and a plurality of ceramic bases disposed on and inside the ceramic base and electrically connected to respective electrodes of the semiconductor element. And a ceramic plate joined to the ceramic base in a flexible state so as to form a sealed space between the metallized wiring conductor and the other main surface of the ceramic base. A first metallized electrode for forming a capacitance, which is attached to a surface and electrically connected to one of the metallized wiring conductors, and is opposed to the first metallized electrode on the inner main surface of the ceramic plate. A pressure sensing device package comprising: a second metallized electrode for forming a capacitance, which is attached and electrically connected to another one of the metallized wiring conductors; A package for a pressure detection device, wherein a reinforcing metallized metal layer is formed on substantially the entire outer surface of the plate except for a region corresponding to the second metallized electrode.