JP2002039899A - Package for pressure detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small, high-sensitivity pressure detection apparatus capable of accurately detecting variation in external pressure. SOLUTION: In this package for the pressure detection apparatus, an electrode 7 for forming an electrostatic capacity and a frame 1c surrounding it are provided on one principal surface of an insulating base 1 having a semiconductor device 3 mounted on the other principal surface, and a metallic plate 2 for forming an electrostatic capacity is mounted on the frame 1c, with the center portion of the metallic plate opposed to the electrode 7 and the outer periphery of the metallic plate soldered onto the frame 1c. A protrusion 2a for preventing overflowing of solder is formed between the soldered outer periphery of the inner surface of the metallic plate 2 and the center portion of the metallic plate opposed to the electrode 7.

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. 3, for example, a capacitance type pressure sensing element 22 and a package 27 are provided on a wiring board 21 made of a ceramic material or a resin material.
And a semiconductor element for operation 28 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 with
A metal plate 25 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 functions as the other electrode for forming a capacitance, And an external lead terminal 26 for electrically connecting the electrode 23 and the metal plate 25 to the outside, respectively, and the metal plate 25 is bent in response to an external pressure to form each capacitance. The capacitance formed between the electrode 23 and the metal plate 25 changes. The change in the capacitance is subjected to arithmetic processing by the arithmetic semiconductor element 28, whereby the external pressure can be detected.

[0003]

However, according to this conventional pressure detecting device, the pressure-sensitive element 22 and the semiconductor element 28
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 28 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. 2000-191.
236, an insulating substrate having a mounting portion on one main surface on which a semiconductor element is mounted, and a plurality of wiring conductors disposed on the surface and inside of the insulating substrate and electrically connected to respective electrodes of the semiconductor element. And an 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; And a metal plate for forming a capacitance, which is joined in a flexible state so as to form a sealed space between the wiring conductor and a central portion of the wiring conductor, and which is electrically connected to another one of the wiring conductors. A device package was proposed. According to this pressure detecting device package, an electrode for forming a capacitance is provided on the other main surface of an insulating base having a mounting portion on which a semiconductor element is mounted on one main surface, and an electrostatic capacitor facing the electrode is provided. Since the metal plate for forming the capacitor is joined in a flexible state so as to form a closed space between the other main surface of the insulating base, the pressure-sensitive element is integrated with the package containing the semiconductor element. As a result, it is 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 capacitance generated between these wirings. Things. In the package for a pressure detecting device proposed in Japanese Patent Application No. 2000-191236, a frame made of ceramics or metal is provided on the outer peripheral portion of the other main surface of the insulating base so as to surround the electrode at the central portion of the main surface. The metal plate was joined to the insulating base by brazing the outer periphery of the metal plate on the frame via a brazing material such as silver-copper braze.

However, according to the pressure detecting device package proposed in Japanese Patent Application No. 2000-191236, the outer peripheral portion of a metal plate is brazed on a frame made of ceramics or metal via a brazing material such as silver-copper brazing material. When the brazing material is used, a large amount of the brazing material easily flows into the central portion of the metal plate, and the capacitance formed between the electrode of the insulating base and the metal plate due to such a large amount of the brazing material flowing out. There is a problem in that the pressure greatly varies, and it is difficult to accurately detect the external pressure.

The present invention has been completed in view of the above-mentioned problems, and has as its object to provide a pressure detecting device which is small in size, has high sensitivity, and is capable of accurately detecting external pressure without variation. Is to provide.

[0007]

A package for a pressure detecting device according to the present invention has a mounting portion on which a semiconductor element is mounted on one main surface and an electrode for forming a capacitance at the center of the other main surface. , A frame joined to the outer periphery of the other main surface of the insulation base so as to surround the electrode, and a center opposed to the electrode and an outer periphery brazed onto the frame. And a metal plate for forming a capacitance, which is attached in a flexible state so as to form a sealed space between the metal plate and the insulating substrate. A projection for preventing brazing material outflow is formed between a brazed outer peripheral portion of the side surface and a central portion facing the electrode.

According to the pressure detecting device package of the present invention, an electrode for forming a capacitance is provided at the center of the other main surface of the insulating base having the mounting portion on which the semiconductor element is mounted on one main surface. At the same time, the metal plate for forming the capacitance facing the electrode is joined in a flexible state so as to form a sealed space between the electrode and the insulating base. The pressure element is formed integrally, so that the pressure detecting device can be reduced in size and the wiring connecting the electrode for pressure detection and the semiconductor element is shortened, and unnecessary static electricity generated between these wirings is reduced. The capacitance can be reduced. Furthermore, since a projection for preventing the brazing material from flowing out is formed between the brazed outer peripheral portion of the inner surface of the metal plate and the central portion facing the electrode, the brazing material is used when brazing the metal plate and the frame. A part of the brazing material is prevented from flowing out to the central part of the metal plate by the protrusion for preventing the brazing material from flowing out. As a result, the capacitance formed between the electrode of the insulating base and the metal plate causes the brazing material to flow out. Does not occur.

[0009]

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 a metal plate, and 3 is a semiconductor element.

The insulating substrate 1 is made of a ceramic material such as a sintered body of aluminum oxide, a sintered body of aluminum nitride, a sintered body of mullite, a sintered body of silicon carbide, a sintered body of silicon nitride, and glass-ceramics. For example, in the case of an aluminum oxide sintered body, an organic binder suitable for ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc.
A solvent, a plasticizer, and a dispersant are added and mixed to form a slurry, and this is formed into a sheet by employing a conventionally known doctor blade method to obtain a plurality of ceramic green sheets. The green ceramic sheet is subjected to appropriate punching, laminating, and cutting to obtain a green ceramic molded body for the insulating substrate 1 and is fired at a temperature of about 1600 ° C. to produce the green ceramic molded body.

The insulating 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 central portion 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 mounted on the mounting portion 1b and a resin sealing such as an epoxy resin is formed in the concave portion 1a. The semiconductor element 3 is sealed by filling the material 4. 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 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 member made of a conductive material, each electrode of the semiconductor element 3 is electrically connected to each metallized wiring conductor 5, 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 is formed by connecting each electrode of the semiconductor element 3 to an external electric circuit and the electrode 7
Function as a conductive path for electrical connection to the electrode, a part of which is led out to the lower surface of the outer periphery of the insulating base 1, and another part is an electrode 7
-It is electrically connected to the metal plate 2. Then, each electrode of the semiconductor element 3 is electrically connected to the metallized wiring conductor 5 via a conductive bonding material 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 insulating base 1 to the wiring conductor of the external electric circuit board via a conductive bonding material such as solder. Will be done.

The metallized wiring conductor 5 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, dispersant and the like. The metallized paste obtained as described above is applied to a ceramic green sheet for the insulating substrate 1 in a predetermined pattern by employing a conventionally known screen printing method, and is fired together with the green ceramic molded body for the insulating substrate 1 for insulation. 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. In this case, 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 frame 1c made of the same material as the insulating substrate 1 and having a height of about 0.01 to 5 mm is provided on the outer peripheral portion of the upper surface of the insulating substrate 1, so that the bottom surface is substantially flat at the center of the upper surface. A recess 1d is formed. This recess 1d
As will be described later, this is for forming a closed space between the metal plate 2 and the bottom surface of the concave portion 1d. An electrode 7 for forming a capacitance is attached to the bottom surface of the concave portion 1d.

The electrode 7 is for forming a capacitance for a pressure-sensitive element together with a metal plate 2 described later, and is formed, for example, in a substantially circular pattern. The electrode 7 is connected to one of the metallized wiring conductors 5a. When 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, a semiconductor is formed. The electrode of the element 3 and the electrode 7 are electrically connected.

Such an electrode 7 is made of metallized metal powder such as tungsten, molybdenum, copper, silver, etc., and is obtained by adding a suitable organic binder, solvent, plasticizer, dispersant to metal powder such as tungsten. The metallized paste is printed and applied on a ceramic green sheet for the insulating substrate 1 by employing a conventionally known screen printing method, and is fired together with the green ceramic molded body for the insulating substrate 1 so that the metallized paste is formed on the bottom surface of the concave portion 1d of the insulating substrate 1. It is formed in a predetermined pattern. The thickness of the exposed surface of the electrode 7 is usually 1 to 1 in order to prevent the electrode 7 from being oxidized and corroded.
A nickel plating layer of about 10 μm is applied.

A frame-shaped joining metallization layer 8 is attached to the entire upper surface of the frame body 1c of the insulating base 1, and the metal plate 2 is made of silver-metal. It is attached by brazing through a brazing material such as a copper brazing material.

One of the metallized wiring conductors 5b is connected to the bonding metallized layer 8 so that the electrode of the semiconductor element 3 is connected to the metallized wiring conductor 5b via a conductive bonding material such as a solder bump 6. When the electrodes are electrically connected to each other, the metal plate 2 connected to the bonding metallization layer 8 and the electrode of the semiconductor element 3 are electrically connected.

The bonding metallization layer 8 is made of a metal powder metallization such as 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 frame-like pattern on the upper surface of the frame 1c of the insulating substrate 1. The exposed surface of the metallizing layer 8 for bonding is usually formed on the exposed surface of the metallizing layer 8 for bonding in order to prevent the metallizing layer 8 for bonding from being oxidized and corroded and to strengthen the bonding between the metallizing layer 8 for bonding and the brazing material. If the thickness is 1
A nickel plating layer of about 10 μm is applied.

The metal plate 2 attached to the upper surface of the insulating substrate 1 is a substantially flat plate made of a metal such as an iron-nickel-cobalt alloy or an iron-nickel alloy and having a thickness of about 0.01 to 5 mm. It functions as a so-called pressure detecting diaphragm that bends toward the insulating substrate 1 in response to pressure, and at the same time functions as an electrode for forming a capacitance for a pressure-sensitive element together with the above-mentioned electrode 7.

If the thickness of the metal plate 2 is less than 0.01 mm, the mechanical strength of the metal plate 2 is small, and there is a great risk that the metal 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 metal plate 2 is preferably in the range of 0.01 to 5 mm.

Such a metal plate 2 is manufactured into a predetermined shape by, for example, rolling an ingot of an iron-nickel-cobalt alloy or an iron-nickel alloy into a plate shape and performing punching. You. It is preferable that such a metal plate 2 is subjected to barrel polishing after punching to remove unnecessary burrs. The surface of the metal plate 2 exposed to the outside is
In order to prevent oxidative corrosion, the nickel plating layer having a thickness of about 1 to 10 μm and a thickness of about 0.
A gold plating layer of about 1 to 3 μm is sequentially applied.

The metal plate 2 and the metallizing layer 8 for bonding are bonded via a brazing material such as a silver-copper brazing material, so that a closed space is formed between the upper surface of the insulating base 1 and the lower surface of the metal plate 2. Is formed, and the bonding metallized layer 8 and the metal plate 2 are electrically connected.

At this time, the electrode 7 and the metal plate 2 are opposed to each other with a space formed between the insulating base 1 and the metal plate 2 therebetween. A predetermined capacitance is formed in accordance with the area of the electrode 7 and the distance between the electrode 7 and the metal plate 2. When an external pressure is applied to the upper surface of the metal plate 2, the metal plate 2 bends toward the insulating base 1 according to the pressure, and the distance between the electrode 7 and the metal plate 2 changes. Since the capacitance with the metal plate 2 changes, 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 electrode 7 for forming the capacitance is provided on the other main surface of the insulating base 1 on which the semiconductor element 3 is mounted on one main surface.
And the metal plate 2 for forming the capacitance facing the electrode 7 is joined in a flexible state so as to form a sealed space between the metal substrate 2 and the insulating base 1, so that the semiconductor element 3 is accommodated. The container and the pressure-sensitive element are integrated, and as a result, the pressure detection device can be reduced in size. Further, since the electrode 7 for forming the capacitance and the metal plate 2 are connected to the semiconductor element 3 via the metallized wiring conductors 5a and 5b provided on the insulating base 1, the electrode 7 and the metal plate 2 can be connected at a short distance. It can be connected to the semiconductor element 3, and as a result, it is possible to provide a highly sensitive pressure detecting device with a small unnecessary capacitance generated between the metallized wiring conductors 5a and 5b.

When the distance between the electrode 7 and the metal plate 2 is less than 0.01 mm at 1 atm, when a large pressure is applied to the metal plate 2, the electrode 7 comes into contact with the metal plate 2 and the pressure is reduced. Risk of not being able to detect
On the other hand, if it exceeds 5 mm, the capacitance formed between the electrode 7 and the metal plate 2 becomes small, and the sensitivity for detecting pressure tends to be low. Therefore, the electrode 7
The distance between the metal plate 2 and 0.01 to 5 mm in one atmosphere
Is preferable.

Further, on the inner surface of the metal plate 2, a frame-shaped projection 2a for preventing the outflow of the brazing material is provided between the outer peripheral portion brazed to the joining metallized layer 8 and the central portion facing the electrode 7. Is formed. The projections 2a for preventing the brazing material from flowing out include:
When the outer peripheral portion of the metal plate 2 is brazed onto the frame 1c, it functions as a barrier for preventing a part of the brazing material from flowing to the central portion of the metal plate 2; It is formed by performing an etching process or a grinding process. When the outer peripheral portion of the metal plate 2 is brazed to the upper surface of the frame 1c, the protrusion 2a functions as a dam for preventing the outflow of the brazing material, so that the outflow of the brazing material to the central portion of the metal plate 2 is effective. Is prevented. Therefore, in the pressure detecting device package of the present invention, there is no outflow of the brazing material at the center of the metal plate 2, and the capacitance between the electrode 7 and the metal plate 2 is large due to the outflow of the brazing material. There is no variation.

If the height of the projections 2a for preventing the brazing material from flowing out is less than 0.1 mm, the brazing material is applied to the central portion of the metal plate 2 when the outer peripheral portion of the metal plate 2 is brazed to the upper surface of the frame 1c. If the distance exceeds 2 mm, the capacitance formed between the electrode 7 and the metal plate 2 is concentrated on the vicinity of the protrusion 2a. Therefore, even if the central portion of the metal plate 2 is greatly displaced by an external pressure, the rate of change of the capacitance is reduced, and the risk of the sensitivity of the pressure detecting device being lowered is increased. Therefore, the height of the projection 2a is 0.1 to 2 m.
The range of m is preferred. The protrusion 2a has a width of 0.1.
If it is less than 2 mm, when the outer peripheral portion of the metal plate 2 is brazed to the upper surface of the frame 1c, it may not be possible to prevent the brazing material from flowing out to the central portion of the metal plate 2;
If it exceeds, the risk of inhibiting good bending of the metal plate 2 increases. Therefore, the width of the protrusion 2a is preferably in the range of 0.1 to 2 mm.

The metal plate 2 is placed on the frame 1c of the insulating base 1.
In order to join the metallized layer 2 and the metal plate 2, a nickel plating layer having a thickness of 1 to 10 μm is previously applied to the surface of the metallized layer 8 for joining on the frame 1 c.
The insulating base 1 and the metal plate 2 are overlapped with a brazing material foil made of silver-copper brazing having a thickness of about 10 to 200 μm therebetween, and these are heated to a temperature of about 850 ° C. in a reducing atmosphere. The brazing material foil is melted to form the metallized layer 8 for joining and the metal plate 2.
The method of brazing with the outer peripheral part of this is adopted. At this time, since the projection 2a for preventing the outflow of the brazing material is formed between the outer peripheral portion to be brazed and the central portion on the inner surface of the metal plate 2, the brazing material is The outflow is well prevented by the projections 2a.

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 pressure detecting device which is small in size, has high sensitivity, and is capable of accurately detecting external pressure without variation.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in one example of the above-described embodiment, a frame 1c made of the same ceramics as the insulating base 1 is provided on the outer peripheral portion of the upper surface of the insulating base 1, and a metal plate 2 is bonded onto the frame 1c to form the insulating base 1
Although a closed space is provided between the upper surface and the metal plate 2, the present invention, as shown in a sectional view in FIG.
A metal frame 9 made of a metal such as a nickel alloy is joined via a brazing material such as silver-copper brazing, and an outer peripheral portion of the metal plate 2 is formed on the metal frame 9 by a brazing material such as silver-copper brazing. A sealed space may be provided between the insulating base 1 and the metal plate 2 by joining via a hole.

[0033]

As described above, according to the pressure detecting device package of the present invention, the capacitance forming electrode is formed on the other main surface of the insulating base on which the semiconductor element is mounted on one main surface. And a metal plate for forming a capacitance facing the electrode is bonded in a flexible state so as to form a sealed space between the electrode and the insulating base. As a result, the pressure detecting device can be made compact, the size of the pressure detecting device can be reduced, and the wiring connecting the pressure detecting electrode and the semiconductor element can be shortened to reduce unnecessary static electricity generated between these wirings. It is possible to provide a pressure detection device having a small capacity and high sensitivity. Furthermore, since a projection for preventing the outflow of brazing material is formed between the brazed outer peripheral portion of the inner surface of the metal plate and the central portion facing the electrode, brazing between the outer peripheral portion of the metal plate and the frame body is performed. Occasionally, a part of the brazing material is prevented from flowing out to the central portion of the metal plate by the protrusion for preventing the brazing material from flowing out, and as a result, the capacitance formed between the electrode of the insulating base and the metal plate is reduced. Therefore, it is possible to provide a pressure detecting device capable of accurately detecting an external pressure without variation without causing variation due to brazing material outflow.

[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.

[Explanation of symbols]

 1 Insulating base 2 Metal plate 2a Protrusion for preventing brazing material from flowing out 3 Semiconductor element 7 Electrode

Claims (1)

[Claims] An insulating substrate having a mounting portion on one of the main surfaces on which a semiconductor element is mounted and an electrode for forming a capacitance formed on a central portion of the other main surface; A frame joined to the outer peripheral portion of the other main surface so as to surround the electrode, and a central portion is opposed to the electrode and an outer peripheral portion is brazed on the frame, between the insulating base. A package for a pressure detecting device, comprising: a metal plate for forming a capacitance, which is attached in a flexible state so as to form an enclosed space, wherein the metal plate is provided with the brazed inner surface thereof. A projection for a brazing filler metal is formed between an outer peripheral portion and a central portion facing the electrode, and a package for a pressure detecting device is provided.