JP4557406B2 - Package for pressure detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure detection device package used in a pressure detection device for detecting pressure.
[0002]
[Prior art]
Conventionally, a capacitance type pressure detection device is known as a pressure detection device for detecting pressure. For example, as shown in a cross-sectional view in FIG. 2, the capacitance type pressure detection device is accommodated in a capacitance type pressure sensitive element 22 and a package 28 on a wiring substrate 21 made of a ceramic material or a resin material. And a semiconductor element 29 for operation. The pressure sensitive element 22 is made of, for example, an electrically insulating material such as a ceramic material, and has an insulating base 24 having a concave portion in which one electrode 23 for forming a capacitance is attached at the center of the upper face, and an upper face of the insulating base 24 And an insulating plate 26 which is joined in a flexible state so as to form a sealed space with the insulating base 24, and the other electrode 25 for forming a capacitance is attached to the lower surface, and each capacitance It is composed of external lead terminals 27 for electrically connecting the forming electrodes 23 and 25 to the outside, and the insulating plate 26 bends in response to external pressure, thereby forming each capacitance. The capacitance formed between the electrodes 23 and 25 changes. Then, the external pressure can be detected by performing arithmetic processing on the change in the electrostatic capacitance by the semiconductor element 29 for arithmetic operation.
[0003]
[Problems to be solved by the invention]
However, according to this conventional pressure detection device, since the pressure sensitive element 22 and the semiconductor element 29 are individually mounted on the wiring board 21, the pressure detection device becomes large and the pressure detection electrode 23 is increased. The wiring between 25 and the semiconductor element 29 becomes long, and an unnecessary electrostatic capacity is formed between the long wiring, so that the sensitivity is low.
[0004]
Accordingly, the applicant of the present application previously disclosed in Japanese Patent Application No. 2000-178618, an insulating base having a mounting portion on which one of the main surfaces is mounted with a semiconductor element, and the surface of and inside the insulating base. A plurality of wiring conductors that are electrically connected to each other, and a second electrode for forming a capacitance that is attached to the 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 between one electrode and the other main surface of the insulating base and a central portion of the main surface, and an inner main surface of the insulating plate A pressure sensing device package comprising a second electrode for forming a capacitance that is deposited opposite to the first electrode and electrically connected to the other one of the wiring conductors has been proposed. According to this pressure detection device package, the first electrode for forming a capacitance is provided on the other main surface of the insulating base having the mounting portion on which the semiconductor element is mounted on one main surface. Since the insulating plate having the second electrode for forming the opposing capacitance on the inner surface is joined in a flexible state so as to form a sealed space between the other main surface of the insulating base, A pressure-sensitive element is integrally formed in a package that houses a 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 shortened. Unnecessary capacitance generated between the wirings can be reduced. In the pressure detection device package proposed in Japanese Patent Application No. 2000-178618, 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 first electrode. The insulating plate was joined to the insulating base by brazing the outer peripheral portion of the second electrode onto the frame through a brazing material such as silver-copper brazing.
[0005]
However, according to the package for a pressure detection device proposed in Japanese Patent Application No. 2000-178618, the outer peripheral portion of the second electrode of the insulating plate is placed on a frame made of ceramic or metal via a brazing material such as silver-copper brazing. When brazing, the thickness of the brazing material that joins the two is difficult to be constant due to variations in brazing temperature, atmosphere, load, etc., so that the distance between the first electrode and the second electrode varies greatly. At the same time, a part of the brazing material joining the two tends to flow out to the center of the second electrode in a large amount. Then, the capacitance formed between the first electrode and the second electrode varies greatly due to such a variation in the distance between the first electrode and the second electrode and the brazing material that has flowed out to the center of the second electrode. As a result, it has been difficult to accurately detect the external pressure.
[0006]
The present invention has been completed in view of the above-described problems, and an object of the present invention is to provide a pressure detection device that is small in size and high in sensitivity and can accurately detect external pressure without variation. There is.
[0007]
[Means for Solving the Problems]
The package for a pressure detection device of the present invention has a plurality of wiring conductors inside and on the surface, and a mounting portion on which a semiconductor element is mounted on one main surface, and is electrically connected to one wiring conductor on the other main surface. An insulating substrate having a connected first electrode for forming a capacitance and a frame-like bonding metallization layer surrounding the first electrode and electrically connected to the other one of the wiring conductors, and one main surface Having a second electrode for forming a capacitance whose central portion faces the first electrode and whose outer peripheral portion is brazed to the metallization layer for bonding, and a sealed space is formed between the other main surface of the insulating substrate. A package for a pressure detecting device comprising an insulating plate joined to an insulating base in a flexible state so as to form, wherein the second electrode has a brazed outer peripheral portion and a central portion facing the first electrode A frame-like shape in contact with the other main surface of the insulating base Edge layer is characterized in that it is deposited.
[0008]
According to the pressure sensing device package of the present invention, the first 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. Since the insulating plate having the second electrode for forming the capacitance facing the first electrode is joined in a flexible state so as to form a sealed space between the insulating substrate and the semiconductor element, As a result, the pressure sensing element can be made compact, and the wiring for connecting the pressure sensing electrode and the semiconductor element can be made short, and the space between these wirings can be reduced. Unnecessary capacitance generated in the circuit can be reduced. Furthermore, since the insulating layer that contacts the insulating base is attached between the outer peripheral portion of the second electrode brazed to the bonding metallization layer of the insulating base and the central portion facing the first electrode, the first electrode And a second electrode in which a brazing material that joins the joining metallization layer and the second electrode is opposed to the first electrode. As a result, there is no large variation in the capacitance formed between the first electrode and the second electrode.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of a pressure detection device package according to the present invention, in which 1 is an insulating substrate, 2 is an insulating plate, and 3 is a semiconductor element.
[0010]
The insulating 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, a silicon carbide sintered body, a silicon nitride sintered body, or glass-ceramics. For example, in the case of an aluminum oxide sintered body, an appropriate organic binder, solvent, plasticizer, and dispersant are added to and mixed with ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. Then, it is made into a mud shape and formed into a sheet shape by adopting a conventionally known doctor blade method, and then a plurality of ceramic green sheets are obtained. -A green ceramic molded body for the insulating substrate 1 is obtained by cutting, and the green ceramic molded body. It is manufactured by firing at a temperature of about 1600 ° C..
[0011]
The insulating base 1 is formed with a recess 1a for accommodating the semiconductor element 3 at the center of the lower surface thereof, thereby functioning as a container for accommodating the semiconductor element 3. The central portion of the bottom surface of the recess 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 the resin sealing such as an epoxy resin is provided in the recess 1a. The semiconductor element 3 is sealed by filling the material 4. In this example, the semiconductor element 3 is sealed by filling the recess 1a with a resin sealing material 4. However, the semiconductor element 3 has a lid made of metal or ceramics on the lower surface of the insulating base 1 to form the recess 1a. It may be sealed by bonding so as to block.
[0012]
Also, a plurality of metallized wiring conductors 5 connected to the respective electrodes of the semiconductor element 3 are led out to the mounting portion 1b. The metallized wiring conductor 5 and the respective electrodes of the semiconductor element 3 are connected to a conductive material such as a solder bump 6 or the like. The electrodes of the semiconductor element 3 and the metallized wiring conductors 5 are electrically connected to each other through the conductive bonding member made of the semiconductor element 3 and the semiconductor element 3 is fixed to the mounting portion 1b. In this example, the electrode of the semiconductor element 3 and the metallized wiring conductor 5 are connected via the solder bumps 6. However, the electrode of the semiconductor element 3 and the metalized wiring conductor 5 are connected to other types of electric wires such as bonding wires. It may be connected by a general connection means.
[0013]
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 electrode 7 and a second electrode 9 to be described later. It leads to the outer peripheral lower surface, and another part is electrically connected to the first electrode 7 and the second electrode 9. Each electrode of the semiconductor element 3 is electrically connected to these metallized wiring conductors 5 through a conductive bonding material and the semiconductor element 3 is sealed with a resin sealing material 4. The part led out to the lower surface of the outer periphery of the insulating substrate 1 is joined to the wiring conductor of the external electric circuit board via a conductive bonding material such as solder, so that the semiconductor element 3 accommodated therein is electrically connected to the external electric circuit. The Rukoto.
[0014]
Such a metallized wiring conductor 5 is made of metal powder metallization such as tungsten, molybdenum, copper, and silver, and is obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, dispersant, and the like to metal powder such as tungsten. The metallized paste is printed and applied in a predetermined pattern on a ceramic green sheet for the insulating substrate 1 using a well-known screen printing method, and is fired together with a green ceramic molded body for the insulating substrate 1 to thereby form the insulating substrate 1. A predetermined pattern is formed inside and on the surface. In order to prevent the metallized wiring conductor 5 from being oxidized and corroded on the exposed surface of the metallized wiring conductor 5 and to improve the bonding between the metallized wiring conductor 5 and a conductive bonding material such as solder, If so, 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 deposited.
[0015]
A first electrode 7 for forming a capacitance is attached to the center of the upper surface of the insulating substrate 1. The first electrode 7 is for forming a capacitance for a pressure sensitive element together with a second electrode 9 described later, and is formed in a substantially circular pattern, for example. The first electrode 7 is connected to one of the metallized wiring conductors 5a, whereby 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. Then, the electrode of the semiconductor element 3 and the first electrode 7 are electrically connected.
[0016]
The first electrode 7 is made of metal powder metallization such as tungsten, molybdenum, copper, and silver, and is obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, and dispersant to metal powder such as tungsten. The paste is printed and applied to a ceramic green sheet for the insulating substrate 1 by using a conventionally known screen printing method, and is fired together with a green ceramic molded body for the insulating substrate 1 to be predetermined at the center of the upper surface of the insulating substrate 1. The pattern is formed. In order to prevent the first electrode 7 from being oxidatively corroded, a nickel plating layer having a thickness of about 1 to 10 μm is usually applied to the exposed surface of the first electrode 7.
[0017]
In addition, a substantially circular frame-shaped bonding metallization layer 8 surrounding the first electrode 7 is deposited on the outer peripheral portion of the upper surface of the insulating substrate 1, and the second electrode 9 is formed on the lower surface of the bonding metallization layer 8. Is attached by brazing the outer peripheral portion of the second electrode 9 and the metallizing layer 8 for bonding through a brazing material such as a silver-copper brazing material.
[0018]
One metal metallization wiring conductor 5b is connected to the metallization layer 8 for bonding, whereby the electrode of the semiconductor element 3 is electrically connected to the metallized wiring conductor 5b via a conductive bonding material such as a solder bump 6. When connected to, the electrode of the semiconductor element 3 and the second electrode 9 are electrically connected.
[0019]
The metallization layer 8 for bonding is made of metal powder metallization such as tungsten, molybdenum, copper, and silver. A metallized paste obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, and dispersing agent to metal powder such as tungsten. A conventionally known screen printing method is used to print and apply to a ceramic green sheet for the insulating substrate 1, and this is fired together with a green ceramic molded body for the insulating substrate 1, thereby forming a frame-like shape on the outer periphery of the upper surface of the insulating substrate 1. A predetermined pattern is formed. In order to prevent the bonding metallized layer 8 from being oxidatively corroded on the exposed surface of the bonding metallized layer 8 and to strengthen the bonding between the bonding metallized layer 8 and the brazing material, it is usual. For example, a nickel plating layer having a thickness of about 1 to 10 μm is applied.
[0020]
The insulating plate 2 attached to the upper surface of the insulating substrate 1 is made of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon nitride sintered body, or a silicon carbide sintered body. A flat plate having a thickness of 0.01 to 5 mm and made of a ceramic material such as glass-ceramics, and functions as a so-called pressure detection diaphragm that bends toward the insulating substrate 1 in response to external pressure. To do.
[0021]
In addition, since the mechanical strength of the insulating plate 2 is less than 0.01 mm when the thickness is less, there is a greater risk of being destroyed when a large external pressure is applied thereto. On the other hand, when it exceeds 5 mm, it becomes difficult to bend at 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.
[0022]
If such an insulating plate 2 is made of, for example, an aluminum oxide sintered body, a suitable organic binder, solvent, plasticizer, dispersion for ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, etc. A ceramic green sheet is obtained by adding an agent and mixing it into a mud and forming it into a sheet using the well-known doctor blade method, and then punching or cutting the ceramic green sheet appropriately. The raw ceramic molded body for the insulating plate 2 is obtained by processing, and the raw ceramic molded body is manufactured by firing at a temperature of about 1600 ° C.
[0023]
Further, a substantially circular or substantially octagonal second electrode 9 for forming a capacitance is attached to the lower surface of the insulating plate 2. The second electrode 9 functions as an electrode for forming a capacitance for a pressure sensitive element together with the first electrode 7 described above, and as a bonding base metal layer for bonding the insulating plate 2 to the insulating substrate 1. Function.
[0024]
The second electrode 9 is made of metal powder metallization such as tungsten, molybdenum, copper, or silver, and is obtained by adding and mixing an appropriate organic binder, solvent, plasticizer, or dispersant to metal powder such as tungsten. The paste is printed and applied to a ceramic green sheet for the insulating plate 2 using a well-known screen printing method, and is fired together with a green ceramic molded body for the insulating plate 2 so that the paste is applied to substantially the entire lower surface of the insulating plate 2. A predetermined pattern is formed. Note that the thickness of the exposed surface of the second electrode 9 is usually 1 in order to prevent the second electrode 9 from being oxidatively corroded and to improve the bonding between the second electrode 9 and the brazing material. A nickel plating layer of about ˜10 μm is applied.
[0025]
The second electrode 9 and the metallizing layer 8 for bonding are bonded via a brazing material such as a silver-copper brazing material, whereby a sealed space is formed between the upper surface of the insulating substrate 1 and the lower surface of the insulating plate 2. Is formed and the metallization layer 8 for bonding and the second electrode 9 are electrically connected.
[0026]
At this time, the first electrode 7 and the second electrode 9 are opposed to each other with a space formed between the insulating base 1 and the insulating plate 2 interposed therebetween. A predetermined capacitance is formed according to the area of the two electrodes 9 and the distance between the first electrode 7 and the second electrode 9. 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 in accordance with the pressure, and the interval between the first electrode 7 and the second electrode 9 changes. Since the capacitance between the first electrode 7 and the second electrode 9 changes, it functions as a pressure-sensitive element that senses a change in external pressure as a change in capacitance. Then, the change in electrostatic capacity is transmitted to the semiconductor element 3 accommodated in the recess 1a through the metallized wiring conductors 5a and 5b, and this is processed by the semiconductor element 3 so as to know the magnitude of the external pressure. be able to.
[0027]
Thus, according to the package for a pressure detection device of the present invention, the first electrode 7 for forming a 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. In addition, the insulating plate 2 having the second electrode 9 for forming a capacitance facing the first electrode 7 on the inner surface is joined in a flexible state so as to form a sealed space with the insulating base 1. Therefore, the container for housing the semiconductor element 3 and the pressure sensitive element are integrated, and as a result, the pressure detection device can be miniaturized. Further, since the first electrode 7 and the second electrode 9 for forming the capacitance are connected to the semiconductor element 3 through the metallized wiring conductors 5a and 5b provided on the insulating base 1, the first electrode 7 and the second electrode 9 are formed. The electrode 9 can be connected to the semiconductor element 3 at a short distance, and as a result, a highly sensitive pressure detecting device is provided by reducing unnecessary capacitance generated between the metallized wiring conductors 5a and 5b. Can do.
[0028]
Furthermore, the surface of the second electrode 9 has a substantially circular frame shape that abuts on the upper surface of the insulating substrate 1 between the outer peripheral portion brazed to the bonding metallization layer 8 and the central portion facing the first electrode 7. The insulating layer 10 is deposited. The insulating layer 10 is made of, for example, a ceramic material that is substantially the same as that of the insulating plate 2. When the outer peripheral portion of the second electrode 9 is brazed to the bonding metallized layer 8, the first electrode 7 and the second electrode 9 are formed. And function as a dam member for preventing a part of the brazing material from flowing out to the central portion of the second electrode 9. The frame-like insulating layer 10 that contacts the upper surface of the insulating substrate 1 between the outer peripheral portion brazed to the bonding metallization layer 8 of the second electrode 9 and the central portion facing the first electrode 7 in this way. Therefore, when the outer peripheral portion of the second electrode 9 is brazed to the bonding metallized layer 8, the distance between the insulating base 1 and the insulating plate 2 is accurately defined by the thickness of the insulating layer 10, Therefore, it is possible to effectively prevent a large variation in the distance between the first electrode 7 and the second electrode 9. At the same time, the insulating layer 10 effectively prevents a part of the brazing material from flowing out to the central portion of the second electrode 9. Therefore, according to the package for the pressure detection device of the present invention, the capacitance formed between the first electrode 7 and the second electrode 9 does not vary greatly, and the external pressure is accurately detected. It is possible to provide a pressure detection device that can do this.
[0029]
If the thickness of the insulating layer 10 is less than 0.01 mm, when the large pressure is applied to the insulating plate 2, the first electrode 7 and the second electrode 9 come into contact with each other and the pressure cannot be detected. On the other hand, if the thickness exceeds 0.2 mm, the bonding metallized layer 8 and the outer periphery of the second electrode 9 are bonded together when the bonding metallized layer 8 and the outer periphery of the second electrode 9 are brazed. It tends to be difficult to bond well with high airtightness. Therefore, the thickness of the insulating layer 10 is preferably in the range of 0.01 to 0.2 mm. Further, when the width of the insulating layer 10 is less than 0.1 mm, the brazing material is prevented from flowing out to the central portion of the second electrode when the outer peripheral portion of the second electrode 9 is brazed to the bonding metallized layer 8. There is a risk that you will not be able to. Therefore, the width of the insulating layer 10 is preferably 0.1 mm or more.
[0030]
Such an insulating layer 10 is formed by using an insulating paste obtained by adding and mixing an appropriate organic binder and solvent to the raw material powder substantially the same as the raw material powder contained in the ceramic green sheet for the insulating plate 2. On the metal paste for the second electrode 9 printed and applied to the ceramic green sheet for printing, a screen printing method known in the art is employed to apply a predetermined pattern to the green ceramic molded body for the insulating plate 2 and By baking together with the metal paste for the two electrodes 9, a frame-like pattern is deposited between the brazed outer peripheral portion of the second electrode 9 and the central portion facing the first electrode 7.
[0031]
In order to bond the insulating plate 2 to the insulating substrate 1, a nickel plating layer having a thickness of 1 to 10 μm is previously deposited on the surfaces of the bonding metallization layer 8 and the second electrode 9, and the bonding metallization is performed. The insulating substrate 1 and the insulating plate 2 are overlapped with the brazing material foil made of silver-copper brazing having a thickness of about 10 to 200 μm between the layer 8 and the second electrode 9, and these are placed in a reducing atmosphere in a reducing atmosphere. A method is adopted in which the brazing material foil is melted by heating to a temperature of ° C. and the bonding metallized layer 8 and the outer peripheral portion of the second electrode 9 are brazed.
[0032]
Thus, according to the above-described package for the pressure detection 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 pressure detection device is small and highly sensitive, and can accurately detect external pressure without variation.
[0033]
Note that 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 the example of the embodiment described above, the insulating layer 10 applied to the second electrode 9 is formed of substantially the same material as the insulating plate 2, but the insulating layer 10 is made of a material different from that of the insulating plate 2. It may be formed. In this case, as the material different from the insulating plate 2, a glass or ceramic material having a softening point higher than the melting point of the brazing material for joining the joining metallized layer 8 and the second electrode 9 may be used. The insulating layer 10 may be formed by applying an insulating paste for ceramics in a predetermined frame shape on the second electrode 9 applied to the insulating plate 2 and baking it at a high temperature.
[0034]
【The invention's effect】
As described above, according to the pressure detection device package of the present invention, the first electrode for forming the capacitance is provided on the other main surface of the insulating base on which the semiconductor element is mounted on one main surface. Since the insulating plate having the second electrode for forming the electrostatic capacitance facing the first electrode is joined in a flexible state so as to form a sealed space between the insulating base and the semiconductor element, the semiconductor element is accommodated. As a result, the pressure detecting device can be reduced in size, and the wiring for connecting the pressure detecting electrode and the semiconductor element can be shortened and generated between these wirings. It is possible to provide a highly sensitive pressure detecting device with a small unnecessary capacitance. Furthermore, since the insulating layer that contacts the insulating base is attached between the outer peripheral portion of the second electrode brazed to the bonding metallization layer of the insulating base and the central portion facing the first electrode, the first electrode And a second electrode in which a brazing material that joins the joining metallization layer and the second electrode is opposed to the first electrode. As a result, the capacitance formed between the first electrode and the second electrode does not vary greatly, and the external pressure is accurately detected without variation. It is possible to provide a pressure detecting device capable of performing the above.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a package for a pressure detection device of the present invention.
FIG. 2 is a cross-sectional view showing a conventional pressure detection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Insulation base | substrate 2 ... Insulation board 3 ... Semiconductor element 7 ... 1st electrode 8 ... Metallization layer 9 for joining ... Two electrodes
10: Insulating layer

Claims (1)

A mounting portion having a plurality of wiring conductors inside and on the surface and mounting a semiconductor element on one main surface, and for forming a capacitance electrically connected to one of the wiring conductors on the other main surface An insulating substrate having a first electrode and a frame-like joining metallization layer surrounding the first electrode and electrically connected to the other one of the wiring conductors, and a central portion on one main surface of the first electrode A second electrode for forming a capacitance that is brazed to the bonding metallization layer and has a flexible state so as to form a sealed space with the other main surface And the insulating plate bonded to the insulating substrate, wherein the second electrode is disposed between the brazed outer peripheral portion and the central portion facing the first electrode. A frame-like insulating layer that is in contact with the other main surface is applied. Package for pressure detection apparatus according to claim and.

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