JP2003130744A - Package for pressure-detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-detecting apparatus for accurately detecting an external pressure. SOLUTION: A first electrode 7 for forming capacitance is provided on one main surface of an insulating substrate 1 where a semiconductor device 3 is mounted to the other main surface. At the same time, an insulating board 2 having a second electrode 9 for forming capacitance that opposes the first electrode 7 on the inner, main surface is brazed to the insulating substrate 1 in a flexible state for forming a closed space at an area to the insulating substrate 1 in the package for a pressure-detecting apparatus. In the package, the insulating board 2 is warped to the side of the insulating substrate 1. The insulating board 2 is constantly deflected in proportion to the external pressure, thus accurately detecting the external pressure.

Description

Description: 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. 2. Description of the Related Art Conventionally, a capacitance type pressure detecting device has been known as a pressure detecting device for detecting pressure. As shown in a sectional view of FIG. 2, for example, a capacitance type pressure sensing device 22 and a package 28 are mounted on a wiring board 21 made of a ceramic material or a resin material.
And a semiconductor element 29 for arithmetic operation 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 to which
An insulating plate 26, which is joined in a flexible state on the upper surface of the insulating substrate 24 so as to form a sealed space between the insulating substrate 24 and the other electrode 25 for forming a capacitance on the lower surface, Each of the electrodes 23 and 25 for forming a capacitance includes an external lead terminal 27 for electrically connecting the electrode to the outside, and each of the capacitances is formed by bending the insulating plate 26 according to an external pressure. The capacitance formed between the forming electrodes 23 and 25 changes. An external pressure can be detected by subjecting this change in capacitance to arithmetic processing by the semiconductor element 29 for arithmetic operation. [0003] However, according to this conventional pressure detecting device, the pressure-sensitive element 22 and the semiconductor element 29 are not provided.
Are individually mounted on the wiring board 21, which increases the size of the pressure detection device and the pressure detection electrode.
The wiring between 23 and 25 and the semiconductor element 29 becomes longer,
There is a problem that the sensitivity is low because an unnecessary capacitance is formed between the long wires. Accordingly, the applicant of the present application has previously filed Japanese Patent Application No. 2000-178.
618, an insulating substrate 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 substrate and electrically connected to respective electrodes of the semiconductor element. A first electrode for forming a capacitance, which is attached to a 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 with the central portion of the main surface; and an inner main surface of the insulating plate, which is adhered to the first electrode so as to face the first electrode. A pressure sensing device package including a second electrode for forming a capacitance electrically connected to another one is proposed. According to the pressure detecting device package,
A first 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 a first electrode for forming a capacitance opposing the first electrode is provided. Since the insulating plate having the two electrodes on the inner surface is joined in a flexible state so as to form a sealed space between the insulating plate and the other main surface of the insulating base, the insulating plate is pressure-sensitive to the package containing the semiconductor element. The elements are formed integrally, which makes it possible to reduce the size of the pressure detecting device and to shorten the wiring connecting the electrode for pressure detection and the semiconductor element, thereby reducing unnecessary static electricity generated between these wirings. The capacity can be reduced. In the pressure sensing device package proposed in Japanese Patent Application No. 2000-178618, the insulating plate is formed by appropriately punching or cutting a ceramic green sheet containing a ceramic raw material powder and an organic binder. And a green ceramic molded body was obtained by firing the green ceramic molded body at a temperature of about 1600 ° C. However, according to the pressure detecting device package proposed in Japanese Patent Application No. 2000-178618, when a green ceramic molded body for an insulating plate is fired to manufacture the insulating plate,
Uneven firing shrinkage occurs, and as a result, the resulting insulating plate is likely to be warped to a height of about 5 to 50 μm on the insulating substrate side or the opposite side. If the insulating plate is warped in a direction opposite to the insulating base, the insulating plate is unlikely to bend even when subjected to external pressure, and when the insulating plate is bent to the insulating base due to external pressure. At the inflection point where the state protrudes from the opposite side to the insulating base side toward the insulating base side, the insulating plate flexes instantaneously to the insulating base side without being proportional to the external pressure. There has been a problem that the capacitance formed between the electrode and the second electrode changes abruptly without corresponding to the change in pressure, and therefore, the external pressure cannot be detected accurately. The present invention has been completed in view of the above-described problems, and has as its object to reduce the size and sensitivity of the first electrode and the second electrode when receiving an external pressure. It is an object of the present invention to provide a pressure detecting device in which a capacitance formed therebetween always changes accurately in response to a change in pressure, whereby an external pressure can be accurately detected. A package for a pressure detecting device according to the present invention comprises an insulating base having a mounting portion on one main surface on which a semiconductor element is mounted, and a surface and an inside of the insulating base. And a flexible state in which a substantially disk-shaped closed space is formed between a plurality of wiring conductors to which respective electrodes of the semiconductor element are electrically connected and the other main surface of the insulating base. An insulating plate joined to the insulating base in, a first electrode for forming a capacitance, which is attached to the other main surface of the insulating base in the enclosed space and is electrically connected to one of the wiring conductors; An insulating plate joined to the other main surface of the insulating base in a flexible state so as to form a sealed space between the insulating base and an inner surface of the insulating plate facing the first electrode; And a second electrode for forming a capacitance electrically connected to another one of the wiring conductors. A package for a pressure detecting device, wherein the insulating plate is warped toward the insulating base. According to the pressure detecting device package of the present invention, the first electrode for forming the 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 facing the first electrode on the inner surface is formed on the insulating base in a flexible state so as to form a closed space between the insulating plate and the other main surface. Because of the bonding, the pressure-sensitive element is formed integrally with the package containing the semiconductor element. As a result, the pressure detection device can be downsized, and the wiring for connecting the electrode for pressure detection and the semiconductor element can be formed. As short,
Unnecessary capacitance generated between these wirings can be reduced. Further, since the insulating plate is warped toward the insulating base, the insulating plate easily bends when subjected to external pressure, and the insulating plate protrudes from the state protruding from the side opposite to the insulating base toward the insulating base. Does not exist. Therefore, the insulating plate always bends in proportion to the external pressure, and the external pressure can always be detected accurately. 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 package for a pressure detection device according to the present invention.
1 is an insulating base, 2 is an insulating plate, and 3 is a semiconductor element. The insulating substrate 1 is made of an electrically insulating 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. An approximately square plate-like laminate made of, for example, an aluminum oxide-based sintered body, an organic binder, a solvent, and a ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. A plasticizer and a dispersant are added and mixed to form a slurry, and this is formed into a sheet by employing a well-known doctor blade method to obtain a plurality of ceramic green sheets. By subjecting the sheet to suitable punching, laminating, and cutting, a green ceramic molded body for the insulating base 1 is obtained. It is manufactured by firing the raw ceramic body of approximately 1600 ° C. temperature. 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 center of the bottom surface of the concave portion 1a is a mounting portion 1b on which the semiconductor element 3 is mounted. The semiconductor element 3 is 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 recess 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 recess 1a. May be sealed by joining them so as to close them. 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 and each metallized wiring conductor 5 are electrically connected, and the semiconductor element 3 is fixed to the mounting portion 1b. In this example, the electrodes of the semiconductor element 3 and the metallized wiring conductors 5 are connected via the solder bumps 6, but the electrodes of the semiconductor element 3 and the metallized wiring conductors 5 are connected to another type of electric wire such as a bonding wire. May be connected by a dynamic connection means. The metallized wiring conductor 5 functions as a conductive path for electrically connecting each electrode of the semiconductor element 3 to an external electric circuit and a first electrode 7 and a second electrode 9, which will be described later.
A part thereof is led out to the lower surface of the outer periphery of the insulating base 1, and another part is electrically connected to the first electrode 7 and the second electrode 9. The electrodes of the semiconductor element 3 are electrically connected to the metallized wiring conductors 5 via a conductive bonding material, 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. The Rukoto. The metallized wiring conductor 5 is made of a 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 in a predetermined pattern to 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 for insulation. A predetermined pattern is formed inside and on the surface of the base 1. In order to prevent the metallized wiring conductor 5 from being oxidized and corroded and to improve the bonding between the metallized wiring conductor 5 and a conductive bonding material such as solder, 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 that of the insulating base 1 and having an outer shape substantially the same as that of the insulating base 1 and a circular inner periphery having a height of about 0.01 to 5 mm is provided on the outer peripheral portion of the upper surface of the insulating base 1. As a result, a circular recess 1d having a substantially flat bottom surface is formed at the center of the upper surface. The concave portion 1d is for forming a closed space between the concave portion 1d and the insulating plate 2, and a first electrode 7 for forming a capacitance is attached to the bottom surface of the concave portion 1d. I have. The first electrode 7 is for forming a capacitance for a pressure-sensitive element together with a second electrode 9 to be described later, and is formed, for example, in a substantially circular pattern. The first electrode 7 is provided with one of the metallized wiring conductors 5.
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, the electrode of the semiconductor element 3 and the first electrode 7 are electrically connected. It is to be connected. The first electrode 7 is made of metal powder of metal such as tungsten, molybdenum, copper, silver, etc.
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 the green ceramic molded body for the insulating substrate 1 to form a predetermined pattern on the bottom surface of the concave portion 1d of the insulating substrate 1. The exposed surface of the first electrode 7 is usually coated with a nickel plating layer having a thickness of about 1 to 10 μm in order to prevent the first electrode 7 from being oxidized and corroded. On the upper surface of the frame 1c of the insulating base 1, a frame-shaped joining metallization layer 8 is applied over substantially the entire surface thereof. Is attached by brazing the second electrode 9 and the bonding metallized layer 8 via a brazing material such as a silver-copper brazing material. In this example,
Although the joining metallization layer 8 is provided over substantially the entire surface of the frame 1c, it may be provided so that the inner circumference substantially matches the inner circumference of the frame 1c and the outer circumference has a substantially circular or substantially octagonal shape. 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 second electrode 9 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 metal powder metallization such as tungsten, molybdenum, copper, silver, etc.
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-shaped pattern on the upper surface of the frame 1c of the insulating substrate 1. The exposed surface of the joining metallized layer 8 is usually formed on the exposed surface in order to prevent the joining metallized layer 8 from being oxidized and corroded and to strengthen the joining between the joining metallized layer 8 and the brazing material. If the thickness is 1
A nickel plating layer of about 10 μm is applied. The insulating plate 2 attached to the upper surface of the insulating base 1 is made of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon nitride sintered body, a silicon carbide sintered body. It is a substantially plate-like square, octagonal, or circular shape made of a ceramic material such as a sintered body, glass-ceramics, or the like, and has a central part that is bent toward the insulating base 1 in response to an external pressure. Function. And tungsten or molybdenum
A second electrode 9 made of metal powder such as copper or silver is adhered. The outer periphery of the second electrode 9 is bonded to the metallization layer 8 of the insulating base 1 with a brazing material such as silver-copper brazing. The insulating plate 2 is attached to the upper surface of the insulating base 1 by brazing. Thus, a substantially disk-shaped closed space is formed between the insulating base 1 and the insulating plate 2. For example, when the insulating plate 2 is made of a sintered body of aluminum oxide, an organic binder suitable for a ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide is used.・
A solvent, a plasticizer, and a dispersant are added and mixed to form a slurry, which is formed into a sheet by employing a known doctor blade method to form a ceramic green sheet. It is obtained by performing a punching process and a cutting process and firing it at a high temperature of about 1600 ° C. The second electrode 9 attached to the lower surface of the insulating plate 2 is formed by applying a metallized paste for the second electrode 9 to the lower surface of the ceramic green sheet for the insulating plate 2 in a predetermined pattern by screen printing. It is formed by firing this together with the ceramic green sheet for the insulating plate 2. The second electrode 9 attached to the lower surface of the insulating plate 2
Functions as an electrode for forming a capacitance for a pressure-sensitive element together with the above-mentioned first electrode 7, and also functions as a bonding base metal layer for bonding the insulating plate 2 to the insulating base 1. The two electrodes 9 and the bonding metallized layer 8 are made of silver-
By joining via a brazing material such as a copper brazing material, a substantially disk-shaped closed space is formed between the upper surface of the insulating base 1 and the lower surface of the insulating plate 2, and the joining metallization layer 8 and the second electrode 9 are formed. Are electrically connected. At this time, the first electrode 7 and the second electrode 9
They face each other with a closed space formed between the insulating base 1 and the insulating plate 2 therebetween, between them, the area of the first electrode 7 and the second electrode 9, and the first electrode 7 and the second electrode A predetermined capacitance is formed in accordance with the distance from the capacitor 9. And the insulating plate 2
When an external pressure is applied to the upper surface of the substrate, the central portion of the insulating plate 2 bends toward the insulating base 1 in accordance with the external pressure, and the distance between the first electrode 7 and the second electrode 9 changes. Since the capacitance between the electrode 7 and the second electrode 9 changes, it functions as a pressure-sensitive element that detects a change in external pressure as a change in capacitance. Then, the change in the capacitance is applied to the metallized wiring conductors 5a and 5a in the semiconductor element 3 housed in the recess 1a.
The pressure is transmitted through the line b, and is subjected to arithmetic processing by the semiconductor element 3, whereby the magnitude of the external pressure can be known. As described above, according to the pressure detecting device package of the present invention, the first electrode 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. 7 and an insulating plate 2 having a second electrode 9 for forming a capacitance facing the first electrode 7 on an inner surface thereof in a flexible state so as to form a sealed space between the insulating plate 2 and the insulating base 1. Because of the joining, the container accommodating the semiconductor element 3 and the pressure-sensitive element are integrated, and as a result, the pressure detection device can be downsized. Further, since the first electrode 7 and the second electrode 9 for forming the capacitance are connected to the semiconductor element 3 via 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, an unnecessary capacitance generated between the metallized wiring conductors 5a and 5b is reduced to provide a highly sensitive pressure detecting device. Can be. Further, the insulating plate 2 is warped toward the insulating base 1, which is important. By the way, the warpage mentioned here is a warpage when the same pressure is applied to the upper and lower surfaces of the insulating plate 2. As described above, since the insulating plate 2 is warped toward the insulating base 1, the insulating plate is easily bent when receiving an external pressure, and the insulating base 2 is projected from the state where the insulating plate protrudes to the opposite side to the insulating base. There is no inflection point protruding to the side. Therefore, the insulating plate always bends in proportion to the external pressure, and the external pressure can always be accurately detected. As described above, in order to warp the insulating plate 2 toward the insulating substrate 1, the ceramic green sheet for the insulating plate 2 is pressed and deformed when the insulating plate 2 is manufactured, and then fired. By making the firing shrinkage of the metallized paste for the second electrode 9 applied to the ceramic green sheet for the insulating plate 2 larger than the firing shrinkage of the ceramic green sheet for the insulating plate 2, For example, a method of warping due to the difference in the firing shrinkage. The firing shrinkage of the ceramic green sheet or the metallized paste can be controlled by adjusting the density of the ceramic green sheet or the metallized paste. The lower the density of the ceramic green sheet or the metallized paste, the higher the firing shrinkage. When the warpage of the insulating plate 2 is less than 5 μm,
It is difficult to efficiently manufacture the insulating plate 2 having such a small warp. On the other hand, if the insulating plate 2 exceeds 50 μm, the first electrode 7 is not applied when a large external pressure is applied to the insulating plate 2.
And the second electrode 9 may come into contact with each other, making it impossible to detect the external pressure. Therefore, it is preferable that the warpage of the insulating plate 2 be in the range of 5 to 50 μm. If the thickness of the insulating plate 2 is less than 0.01 mm, the risk of breaking the insulating plate 2 when a large pressure is applied to the insulating plate 2 increases.
If it exceeds mm, it becomes difficult to bend under a small pressure, and it is not suitable 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. Further, when the distance between the first electrode 7 and the second electrode 9 is less than 0.01 mm at 1 atm, the insulating plate 2
When a large pressure is applied to the first electrode 7, there is a risk that the first electrode 7 and the second electrode 9 come into contact with each other and the pressure cannot be detected. The capacitance formed between the electrode and the second electrode 9 tends to be small, and the sensitivity for detecting pressure tends to be 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 at 1 atm. The insulating plate 2 is placed on the frame 1c of the insulating base 1.
In order to join the metallized layer 8 and the second metallized layer 9 on the frame 1c, a nickel plating layer having a thickness of 1 to 10 μm is applied in advance to the surfaces thereof. 10-200μ thickness between two electrodes 9
The insulating base 1 and the insulating plate 2 are overlapped with each other with a brazing material foil made of silver-copper brazing having a thickness of about m.
A method is employed in which the brazing material foil is melted by heating to a temperature of about 850 ° C., and the joining metallized layer 8 and the outer peripheral portion of the second electrode 9 are brazed. Thus, according to the pressure detecting device package described above, 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 and has high sensitivity and can accurately detect an external pressure is provided. 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 above-described embodiment, the insulating base 1 and the insulating plate 2 are joined by brazing, but the insulating base 1 and the insulating plate 2 are composed of a ceramic green sheet for the insulating base 1 and the insulating plate 2. May be joined by stacking ceramic green sheets for use together and firing them at the same time to integrate them by sintering. As described above, according to the pressure detecting device package of the present invention, the insulating substrate having the mounting portion on which the semiconductor element is mounted on one main surface is provided on the other main surface. A first electrode for forming a capacitance is provided, and an insulating plate having a second electrode for forming a capacitance facing the first electrode on the inner side surface is formed as a closed space with the other main surface. Because it was bonded to the insulating base in a flexible state,
The pressure-sensitive element is formed integrally with the package containing the semiconductor element. As a result, the pressure detection device can be made small and the wiring connecting the electrode for pressure detection and the semiconductor element is shortened. Unnecessary capacitance generated between the wirings can be reduced. Further, since the insulating plate is warped toward the insulating base, the insulating plate easily bends when subjected to external pressure, and the insulating plate protrudes from the state protruding from the side opposite to the insulating base toward the insulating base. Does not exist. Therefore, the insulating plate always bends in proportion to the external pressure, and it is possible to provide a pressure detecting device capable of always accurately detecting the external pressure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of an embodiment of a package for a pressure detecting device according to the present invention. FIG. 2 is a sectional view showing a conventional pressure detecting device. [Description of Signs] 1 ... Insulating substrate 2 ... Insulating plate 3 ... Semiconductor element 5 ... Wiring conductor 7 ... First electrode 9 ... ..Second electrodes

Claims (1)

Claims: 1. An insulating base having a mounting portion on one main surface on which a semiconductor element is mounted, and an electrode provided on the surface and inside of the insulating base, wherein each electrode of the semiconductor element is provided. Is electrically connected to the insulating base in a flexible state so as to form a substantially disk-shaped closed space between the plurality of wiring conductors electrically connected to each other and the other main surface of the insulating base. A first electrode for forming a capacitance, which is attached to the other main surface of the insulating base in the closed space and is electrically connected to one of the wiring conductors; A pressure electrode comprising: a second electrode for forming a capacitance, which is attached to an inner main surface of the plate so as to face the first electrode and is electrically connected to another one of the wiring conductors. A package for a detection device, wherein the insulating plate is warped toward the insulating base. Package for a pressure detecting device for.