JP4637342B2 - 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.
[0005]
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 sensing device package proposed in Japanese Patent Application No. 2000-178618, the insulating plate is obtained by subjecting the ceramic green sheet containing the ceramic raw material powder and the organic binder to appropriate punching or cutting. In addition to obtaining a green ceramic molded body for use, the green ceramic molded body was produced by firing at a temperature of about 1600 ° C.
[0006]
However, according to the package for the pressure detection device proposed in Japanese Patent Application No. 2000-178618, when firing the raw ceramic molded body for the insulating plate to produce the insulating plate, uneven firing shrinkage occurs, As a result, warpage of about 30 μm is likely to occur in the obtained insulating plate. And when such a curvature generate | occur | produces, the electrostatic capacitance formed between a 1st electrode and a 2nd electrode varies widely, As a result, it is difficult to detect an external pressure correctly. Had a point.
[0007]
The present invention has been completed in view of the above-mentioned problems, and has an object of being small in size and high in sensitivity and having a variation in capacitance formed between the first electrode and the second electrode. An object of the present invention is to provide a small pressure detecting device capable of accurately detecting an external pressure.
[0008]
[Means for Solving the Problems]
The package for a pressure detection device of the present invention has an insulating base having a mounting portion on which a semiconductor element is mounted on one main surface, and is disposed on and inside the surface of the insulating base. A plurality of wiring conductors to be connected, a first electrode for forming a capacitance that 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 the other the main surface, an insulating plate having an outer peripheral portion is brazed in a flexible state so as to form a closed space between said central portion, region and facing the first electrode definitive inside surface of the insulating plate And a second electrode for forming a capacitance that is attached to the outer periphery and electrically connected to the other one of the wiring conductors, the insulating plate on the second electrode Is bonded to an insulating substrate using a brazing material foil having a thickness of 10 to 200 μm. Yes, the distance between the first electrode and the second electrode is 0.01 to 5 mm, and the insulating plate is polished so that the warpage of the inner surface is 10 μm or less smaller than the thickness of the brazing material foil . It is characterized by.
[0009]
According to the package for the pressure detection device of the present invention, the first electrode for forming the electrostatic 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. An insulating plate having a second electrode for forming a capacitance opposite to one electrode on its inner surface was joined to the insulating substrate in a flexible state so as to form a sealed space between the other main surface. Therefore, the pressure-sensitive element is integrally formed in the package that accommodates the semiconductor element. As a result, the pressure detection device can be reduced in size and the wiring for connecting the pressure detection electrode and the semiconductor element can be shortened. Unnecessary capacitance generated between these wirings can be reduced. Furthermore, since the warpage of the inner surface of the insulating plate is polished to be 10 μm or less, there is no large variation in the capacitance formed between the first electrode and the second electrode.
[0010]
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.
[0011]
The insulating substrate 1 is made of an electrically insulating 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, it is a rectangular plate-like laminate, and suitable organic binders, solvents, plasticizers, etc. for ceramic raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide A dispersant is 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, and then suitable for these ceramic green sheets. A green ceramic molded body for the insulating substrate 1 is obtained by performing a punching process, a laminating process, and a cutting process. It is manufactured by firing a click shaped body at a temperature of about 1600 ° C..
[0012]
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.
[0013]
Further, 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, and the metalized wiring conductors 5 and the respective electrodes of the semiconductor element 3 are connected to conductive materials such as solder bumps 6 and 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.
[0014]
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.
[0015]
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.
[0016]
Further, a frame body 1c made of the same material as that of the insulating substrate 1 and having an outer shape substantially the same as the insulating substrate 1 and a circular inner periphery of about 0.01 to 5 mm is provided on the outer peripheral portion of the upper surface of the insulating substrate 1. As a result, a circular recess 1d having a substantially flat bottom surface is formed at the center of the top surface. As will be described later, the recess 1d is for forming a sealed space with the insulating plate 2, and a first electrode 7 for forming a capacitance is attached to the bottom surface of the recess 1d. Yes.
[0017]
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.
[0018]
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 using a conventionally known screen printing method, and is fired together with a green ceramic molded body for the insulating substrate 1 to thereby form a predetermined surface on the bottom surface of the recess 1d 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.
[0019]
In addition, a frame-like bonding metallization layer 8 is deposited on the upper surface of the frame 1c of the insulating substrate 1 over substantially the entire surface, and the bonding metallization layer 8 has an insulation having a second electrode 9 on the lower surface. The plate 2 is attached by brazing the second electrode 9 and the joining metallization layer 8 via a brazing material such as a silver-copper brazing material. In this example, the bonding metallization layer 8 is provided over substantially the entire surface of the frame 1c. However, the inner periphery substantially coincides with the inner periphery of the frame 1c and the outer periphery is substantially circular or substantially octagonal. It may be provided.
[0020]
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. As a result, the second electrode 9 connected to the bonding metallization layer 8 and the electrode of the semiconductor element 3 are electrically connected.
[0021]
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 shape on the upper surface of the frame 1c of the insulating substrate 1. Are formed in a predetermined pattern. 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.
[0022]
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 substantially plate shape such as a square, an octagon, or a circle made of a ceramic material such as glass-ceramics, and functions as a so-called pressure detecting diaphragm whose central portion is bent toward the insulating base 1 in response to an external pressure. A second electrode 9 made of a mixed powder metallization of molybdenum and manganese is deposited on the lower surface thereof, and the outer periphery of the second electrode 9 is applied to the metallization layer 8 for bonding of the insulating substrate 1 with a silver-copper braze. The insulating plate 2 is attached to the upper surface of the insulating substrate 1 by brazing via a brazing material such as.
[0023]
The second electrode 9 attached to the lower surface of the insulating plate 2 functions as an electrode for forming a capacitance for the pressure sensitive element together with the first electrode 7 described above, and the insulating plate 2 is bonded to the insulating base 1. It functions as a bonding base metal layer for bonding, and by bonding the second electrode 9 and the bonding metallization layer 8 via a brazing material such as a silver-copper brazing material, the upper surface of the insulating substrate 1 and the insulating plate 2 A sealed space is formed between the lower surface and the bonding metallized layer 8 and the second electrode 9 are electrically connected.
[0024]
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 central portion of the insulating plate 2 bends toward the insulating base 1 in accordance with the pressure, and the distance between the first electrode 7 and the second electrode 9 changes. As a result, the capacitance between the first electrode 7 and the second 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 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.
[0025]
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.
[0026]
Furthermore, the insulating plate 2 is polished so that the warpage of its lower surface is 10 μm or less, which is important. By the way, the warp here refers to a warp when the same pressure is applied to the upper and lower surfaces of the insulating plate 2. Thus, since the insulating plate 2 is polished so that the warpage of its lower surface is 10 μm or less, the distance between the first electrode 7 and the second electrode 9 under a constant pressure becomes substantially constant. There is no large variation in the capacitance formed between the first electrode 7 and the second electrode 9 under a constant pressure. Therefore, according to the package for a pressure detection device of the present invention, an external pressure can be accurately detected.
[0027]
When the warpage of the lower surface of the insulating plate 2 exceeds 10 μm, the capacitance formed between the first electrode 7 and the second electrode 9 varies greatly, and it is difficult to accurately detect the external pressure. Tend to be. Therefore, the warpage of the lower surface of the insulating plate 2 is specified to be 10 μm or less.
[0028]
Further, when the thickness of the insulating plate 2 is less than 0.01 mm, there is a high risk that the insulating plate 2 will be destroyed when a large pressure is applied to the insulating plate 2. Then, it becomes difficult to bend, 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.
[0029]
Furthermore, when the distance between the first electrode 7 and the second electrode 9 is less than 0.01 mm at 1 atm, when the large pressure is applied to the insulating plate 2, the first electrode 7 and the second electrode 9 are There is a risk that the pressure cannot be detected by contact, and if it exceeds 5 mm, the capacitance formed between the first electrode 7 and the second electrode 9 becomes small, and the pressure is reduced. There is a tendency that the sensitivity to detect is low. Therefore, the distance between the first electrode 7 and the second electrode 9 is preferably in the range of 0.01 to 5 mm in 1 atmosphere.
[0030]
For example, when the insulating plate 2 is made of an aluminum oxide sintered body, the insulating plate 2 is made of a suitable organic binder, solvent, and ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. A plasticizer / dispersant is added and mixed to form a slurry, which is then formed into a sheet using a known doctor blade method to form a ceramic green sheet, and then the ceramic green sheet is appropriately stamped. A ceramic plate for the insulating plate 2 is obtained by baking and cutting at a high temperature of about 1600 ° C., and then polishing the upper and lower surfaces of the ceramic plate with a polishing apparatus so that the warpage is 10 μm or less. Obtained by. Further, the second electrode 9 deposited on the lower surface of the insulating plate 2 has a predetermined metallized paste of molybdenum and manganese for the second electrode 9 applied to the lower surface of the insulating plate 2 whose upper and lower surfaces are polished by a screen printing method. It is formed by printing and applying to a pattern and baking and baking at a temperature of about 1500 ° C.
[0031]
In addition, in order to join the insulating plate 2 on the frame 1c of the insulating base 1, a nickel plating layer having a thickness of 1 to 10 μm is previously formed on the surfaces of the joining metallization layer 8 and the second electrode 9 on the frame 1c. The insulating substrate 1 and the insulating plate 2 are stacked with a brazing material foil made of silver-copper brazing having a thickness of 10 to 200 μm between the metallizing layer 8 for bonding and the second electrode 9. In addition, a method is adopted in which these are heated to a temperature of about 850 ° C. in a reducing atmosphere to melt the brazing material foil and braze the bonding metallized layer 8 and the outer peripheral portion of the second electrode 9.
[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 an external pressure.
[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 above-described embodiment, the second electrode 9 deposited on the lower surface of the insulating plate 2 is printed with a mixed metallized paste of molybdenum and manganese on the lower surface of the insulating plate 2 whose upper and lower surfaces are polished. The second electrode 9 is formed by baking this at a high temperature. The second electrode 9 is formed by sputtering a metal film such as titanium-platinum-gold or titanium-tungsten-copper on the lower surface of the insulating plate 2 whose upper and lower surfaces are polished. It may be formed by adopting the thin film forming technique and sequentially depositing.
[0034]
【The invention's effect】
As described above, according to the pressure detection device package of the present invention, the first main surface for forming the electrostatic capacitance is formed on the other main surface of the insulating substrate having the mounting portion on which the semiconductor element is mounted on one main surface. An electrode is provided, and an insulating plate having a second electrode for forming a capacitance opposite to the first electrode on the inner surface is flexible so as to form a sealed space between the other main surface. Since the pressure sensitive element is integrally formed in the package for housing the semiconductor element, the pressure detecting device can be reduced in size and the pressure detecting electrode and the semiconductor element can be reduced. By making the wiring to be connected short, unnecessary electrostatic capacitance generated between these wirings can be made small. Furthermore, the insulating plate is joined to the insulating base using a brazing material foil having a thickness of 10 to 200 μm provided on the second electrode, and the distance between the first electrode and the second electrode is 0.01 to 5 mm. In addition, since the warping of the inner surface of the insulating plate is 10 μm or less, which is smaller than the thickness of the brazing material foil , the capacitance formed between the first electrode and the second electrode is reduced. It is possible to provide a pressure detection device capable of accurately detecting an external pressure without causing large variations.
[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 5 ... Wiring conductor 7 ... 1st electrode 9 ... 2nd electrode

Claims (1)

An insulating base having a mounting portion on which a semiconductor element is mounted on one main surface; and a plurality of wiring conductors disposed on and inside the insulating base and electrically connected to the electrodes of the semiconductor element; A first 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, and the central portion on the other main surface. depositing a brazed insulating plate, the region and the outer peripheral portion facing the first electrode definitive inside surface of the insulating plate outer peripheral portion in a flexible state so as to form a sealed space between the A package for a pressure detection device comprising a second electrode for forming a capacitance electrically connected to the other one of the wiring conductors,
The insulating plate is bonded to the insulating base using a brazing material foil having a thickness of 10 to 200 μm provided on the second electrode, and the distance between the first electrode and the second electrode is 0. A package for a pressure detecting device , wherein the insulating plate is polished so that the warping of the inner surface thereof is 10 μm or less which is smaller than the thickness of the brazing material foil .

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