JP2005214668A - Package for pressure detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package for a pressure detecting device capable of precisely and satisfactorily detecting external pressure. <P>SOLUTION: The package for the pressure detecting device is provided with an insulating substrate 1 having a mounting part 1b for mounting a semiconductor element 3 to one main surface; a plurality of wiring conductors 5 arranged in the surface and inside of the insulating substrate 1 and electrically connected to each electrode of the semiconductor element 3; an insulating plate 2 joined to the insulating substrate 1 in such a flexible state as to form a sealed space in-between with the other main surface of the insulating substrate 1; a first electrode for forming electrostatic capacitor deposited to the other main surface of the insulating substrate 1 in the sealed space and electrically connected to one of the wiring conductors 5; and a second electrode 9 for forming electrostatic capacitor deposited to a main surface inside the insulating plate 2 in such a way as to be opposed to the first electrode 7 and electrically connected to another one of the wiring conductors 5. A recess is formed in the main surface inside the insulating plate 2, and the internal size of the recess on the side of its bottom surface 2b is larger than that on the side of the insulating substrate 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a package for a pressure detection device used in a pressure detection device for detecting pressure.

  Conventionally, a capacitance type pressure detection device is known as a pressure detection device for detecting pressure. As shown in a cross-sectional view in FIG. 3, this capacitance type pressure detection device has a capacitance type pressure sensitive element 22 and a pressure detection device package on a wiring board 21 made of a ceramic material or a resin material. 28 and a semiconductor element 29 for calculation contained in 28.

  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 with a capacitance forming electrode 23 attached to the center of the upper surface thereof. An insulating plate 26 is bonded to the upper surface in a flexible state so that the concave portion of the insulating base 24 becomes a sealed space, and an electrostatic capacitance forming electrode 25 is attached to the main surface on the sealed space side. Each of the capacitance forming electrode 23 and the electrode 25 is composed of an external lead terminal 27 for electrically connecting to the outside. As a result, the capacitance formed between the electrode 23 and the electrode 25 is changed by bending the insulating plate 26 according to the pressure applied from the outside, and this change is calculated by the semiconductor element 29 for calculation. By doing so, the pressure applied from the outside can be detected.

  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 is enlarged and the pressure detection electrode 23 and The wiring conductor that connects the electrode 25 and the semiconductor element 29 becomes long, and there is a problem that sensitivity is lowered because unnecessary capacitance is generated.

  Therefore, as shown in a cross-sectional view in FIG. 2, an insulating base 11 having a mounting portion 11 b on which the semiconductor element 13 is mounted on one main surface, and the surface and inside of the insulating base 11 are provided. A plurality of wiring conductors 15 that are electrically connected to each other and a central portion of the other main surface of the insulating base 11 are attached to the wiring conductor 15a that is one of the wiring conductors 15 and electrically connected to the wiring conductor 15a. Insulating plate joined in a flexible state so as to form a sealed space between the first electrode 17 for forming capacitance and the other main surface of the insulating substrate 11 and the central portion of the main surface. 12 is formed on the inner surface of the insulating plate 12 so as to face the first electrode 17 and is electrically connected to a wiring conductor 15b, which is another wiring conductor 15. And a second electrode 19 for the pressure sensing device package is proposed. And are (for example, see Patent Document 1 below).

  According to this pressure detection device package, since the pressure sensitive element is integrally formed in the pressure detection device package that accommodates the semiconductor element 13, the pressure detection device can be reduced in size and the pressure detection electrode and The wiring conductor 15 connecting the semiconductor element 13 can be shortened, and unnecessary capacitance generated between the plurality of wiring conductors 15 can be reduced.

  Conventionally, the wiring conductor 15 of the pressure detection device package, the first electrode 17 for forming the capacitance, and the second electrode 19 are 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 dispersant is printed on a ceramic green sheet by a conventionally known screen printing method or the like, and these are ceramics to be the insulating substrate 11 and the insulating plate 12. The green sheet is manufactured by firing together with a green ceramic molded body laminated on top and bottom.

  Further, in order to use the first electrode 17 and the second electrode 19 for forming a capacitance, it is necessary to form a certain space region between the first electrode 17 and the second electrode 19. Alternatively, a sealed space for forming a capacitance is formed between the insulating base 11 and the insulating plate 12 by forming a frame-shaped protruding portion 12a on the outer peripheral portion of the insulating plate 12 and providing a recess surrounded by the protruding portion 12a. Was forming.

  The insulating substrate 11 and the insulating plate 12 are a first bonding metallization layer 18 provided around the first electrode 17 on the insulating substrate 11 and a second bonding material provided on the outer periphery of the insulating plate 12. The metallized layer 20 is attached by bonding with a conductive bonding material such as a brazing material.

In addition, the insulating plate 12 having such a protruding portion 12a is formed with the ceramic green sheet for the protruding portion 12a in which a through hole for forming a sealed space is formed by a punching method or the like, and the second electrode 19. Further, it is formed by laminating a ceramic green sheet for the bottom surface 12b of the concave portion that becomes a sealed space to form a green sheet for the insulating plate 12, and firing at a high temperature.
JP 2001-356064 A

  However, according to the conventional pressure detection device package, when the insulating plate 12 becomes smaller due to the downsizing of the pressure detection device package, the displacement of the bottom surface 12b due to the external pressure becomes small, and the external pressure is detected well. In particular, the outer peripheral portion of the second electrode 19 formed so as to face the first electrode 17 has a very small change due to fluctuations in external pressure, and even if a minute pressure is applied to the insulating plate 12, Since the change in capacitance formed between the first electrode 17 and the second electrode 19 is hardly affected, the sensitivity is lowered.

  Further, if the region of the bottom surface 12b of the insulating plate 12 is to be increased in an attempt to increase the detection sensitivity with respect to the pressure change outside the insulating plate 12, the region of the protrusion 12a becomes narrower. The joint portion between the insulating base 11 and the insulating plate 12 is deteriorated, the airtightness of the sealed space is easily lowered, and the external pressure cannot be detected well. It was.

  The present invention has been completed in view of the above-described conventional problems, and an object of the present invention is to provide a package for a pressure detection device that can detect an external pressure accurately and satisfactorily.

  The package for a pressure detection device according to the present invention includes an insulating base having a mounting portion on which a semiconductor element is mounted on one main surface, and a surface and an inside of the insulating base, and each electrode of the semiconductor element is electrically An insulating plate joined to the insulating substrate in a flexible state so as to form a sealed space between the plurality of wiring conductors connected to the other main surface of the insulating substrate, and the inside of the sealed space A first electrode for forming a capacitance that is attached to the other main surface of the insulating base and is electrically connected to one of the wiring conductors, and a first electrode on the inner main surface of the insulating plate. A package for a pressure detection device, comprising: a second electrode for forming a capacitance that is attached so as to face an electrode and is electrically connected to the other one of the wiring conductors; Has a recess formed in the inner main surface, and the recess has an inner dimension on the bottom side. There, characterized in that it is larger than the inner dimension of the insulating substrate side.

  According to the pressure detection device package of the present invention, the insulating plate has a recess formed on the inner main surface, and the recess has an inner dimension on the bottom surface side larger than an inner dimension on the insulating substrate side. Therefore, by forming the bottom surface of the concave portion of the insulating plate widely, the insulating plate can be made flexible, the external pressure can be detected accurately, and the joint between the insulating base and the insulating plate is widened. Thus, the bondability between the insulating base and the insulating plate can be increased, and the internal pressure can be made highly airtight. Therefore, it can be set as the package for pressure detectors which can detect an external pressure accurately.

  Further, since the area of the bottom surface of the recess of the insulating plate is widened, the end of the bottom surface of the recess can be moved away from the outer periphery of the second electrode formed on the bottom surface of the recess. Also tends to fluctuate well. Therefore, the amount of change in capacitance formed by the first electrode and the second electrode can be increased without reducing the second electrode, and the external pressure can be detected with good sensitivity. .

  Further, it is not necessary to form a large insulating plate, and the pressure detection device package can be formed as a small one.

  Next, the pressure detection device package of 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 detecting device package according to the present invention, wherein 1 is an insulating substrate, 2 is an insulating plate, 3 is a semiconductor element, 7 is a first electrode, and 9 is a second. Electrode.

  The insulating substrate 1 and the insulating plate 2 are 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 a glass ceramic. Consists of. If the insulating base 1 and the insulating plate 2 are made of, for example, an aluminum oxide sintered body, a suitable organic binder, solvent, plastics for ceramic raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide are used. Add and mix the agent and dispersant to make a mud, and by molding this into a sheet by a conventionally known doctor blade method, etc., a plurality of ceramic green sheets are obtained. Appropriate punching, laminating, cutting and the like are performed, and a green ceramic molded body is formed by stacking up and down, and is fired at a temperature of about 1600 ° C.

  The insulating base 1 has a concave portion 1a formed on one main surface (the lower surface in FIG. 1), and the concave portion 1a has a mounting portion 1b for mounting the semiconductor element 3 at the center of the bottom surface. The insulating substrate 1 functions as a container for housing the semiconductor element 3. The semiconductor element 3 is mounted on the mounting portion 1b and sealed by being covered in the recess 1a with a resin sealing material 4 such as an epoxy resin. Alternatively, the insulating base 1 may be sealed by joining a lid made of metal, ceramics, or the like to one main surface so as to close the recess 1a.

  A plurality of wiring conductors 5 are led out to the mounting portion 1b, and the wiring conductor 5 and each electrode of the semiconductor element 3 are joined via a conductive bonding material 6 such as a solder bump, so that the semiconductor element 3 Each electrode and each wiring conductor 5 are electrically connected, and the semiconductor element 3 is attached to the mounting portion 1b. Alternatively, the semiconductor element 3 may be connected to the wiring conductor 5 by other electrical connection means such as a bonding wire.

  The wiring conductor 5 functions as a conductive path for electrically connecting each electrode of the semiconductor element 3 to the external electric circuit, the first electrode 7 and the second electrode 9, and a part thereof is led out to the outer surface of the insulating substrate 1. And connected to the external electric circuit board. Another part of the wiring conductor 5 is electrically connected to the first electrode 7 and the second electrode 9.

  Such a 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 paste is printed and applied in a predetermined pattern on a ceramic green sheet for the insulating substrate 1 by a well-known screen printing method, and this is fired together with a green ceramic molded body for the insulating substrate 1 to form the inside and the surface of the insulating substrate 1. A predetermined pattern is formed. The exposed surface of the wiring conductor 5 has a thickness of 1 in order to prevent the wiring conductor 5 from being oxidatively corroded and to improve the bonding between the wiring conductor 5 and the conductive bonding material 6 such as solder. It is preferable that a nickel plating layer having a thickness of about 10 μm and a gold plating layer having a thickness of about 0.1 to 3 μm are sequentially deposited.

  A first electrode 7 for forming a capacitance is attached to the center of the other main surface (upper surface in FIG. 1) of the insulating substrate 1, and this first electrode 7 is a part of the wiring conductor 5. Is electrically connected to the wiring conductor 5a. The first electrode 7 and the electrode of the semiconductor element 3 are electrically connected by connecting the electrode of the semiconductor element 3 to the wiring conductor 5a via the conductive bonding material 6 such as a solder bump. The first electrode 7 is formed in a circular shape, for example.

  Further, a frame-shaped first bonding metallization layer 8 is deposited on the outer peripheral portion of the other main surface of the insulating base 1 over the entire periphery, and the insulating plate 2 having the metallized layer 8 and a concave portion to be described later. A sealed space is formed between the insulating base 1 and the insulating plate 2 by bonding the second bonding metallization layer 10 via a brazing material such as a silver-copper brazing material.

  The first bonding metallized layer 8 is electrically connected to a wiring conductor 5b, which is one of the metallized wiring conductors 5. The conductive bonding material 6 such as a solder bump is connected to the electrode of the semiconductor element 3 on the wiring conductor 5b. The electrode of the semiconductor element 3 and the second electrode 9 are electrically connected by being electrically connected via.

  The insulating plate 2 has a rectangular shape, a polygonal shape such as an octagonal shape, or a flat plate shape such as a circular shape, and a frame-shaped protruding portion 2a having a height of 0.01 to 5 mm is formed on the outer peripheral portion of one main surface. Thus, a recess is formed. A portion constituting the bottom surface 2b of the concave portion of the insulating plate 2 bends toward the insulating base 1 according to the pressure applied from the outside, and functions as a so-called pressure detection diaphragm.

  The insulating plate 2 has a low mechanical strength when the thickness of the portion constituting the bottom surface 2b of the recess is less than 0.01 mm, and is easily broken when a large external pressure is applied. Further, if the thickness of the portion constituting the bottom surface 2b of the recess exceeds 5 mm, the portion constituting the bottom surface 2b of the recess becomes difficult to bend when the pressure applied from the outside is small, and the accuracy as a pressure detecting diaphragm is likely to decrease. Become. Therefore, the thickness of the portion constituting the bottom surface 2b of the recess of the insulating plate 2 is preferably in the range of 0.01 to 5 mm.

The ratio of the area (mm ² ) of the bottom surface of the recess 2b to the unit thickness (mm) of the insulating plate 2 is preferably about 5 to 500. If it is less than 10, the insulating plate 2 becomes difficult to bend, and the area of the second electrode 9 becomes small, and the sensitivity of pressure detection tends to be lowered. On the other hand, if it exceeds 500, the insulating substrate 1 and the insulating plate 2 are enlarged, and the package is likely to be enlarged, and it is easy to bend due to the weight of the bottom surface 2b of the recess. As a result, the first electrode 7 and the second electrode 9 are likely to come into contact with each other and become difficult to detect with high accuracy.

  A second electrode 9 for forming a capacitance is attached to the bottom surface 2 b of the recess of the insulating plate 2. The second electrode 9 is formed in a circular shape, for example, and forms a capacitance for the pressure sensitive element so as to face the first electrode 7 described above.

  The first electrode 7 and the second electrode 9 as described above are made of metal powder metallization such as tungsten, molybdenum, copper, and silver having a thickness of about 10 to 50 μm, and are formed by the same method as the wiring conductor 5. Further, a nickel plating layer having a thickness of about 1 to 10 μm is preferably deposited on the surfaces of the first electrode 7 and the second electrode 9 in order to prevent oxidative corrosion.

  Further, a polygonal or circular frame-shaped second bonding metallization layer 10 electrically connected to the second electrode 9 is attached to the main surface of the protrusion 2a of the insulating plate 2 on the insulating base 1 side. ing. The second bonding metallization layer 10 functions as a bonding base metal layer for bonding the insulating plate 2 to the insulating substrate 1, and the second bonding metallization layer 10 and the first bonding metallization layer 8 are silver- The first metallization layer 8 for bonding and the second metallization layer 10 for bonding are electrically connected to each other through a brazing material such as copper brazing.

  At this time, the first electrode 7 and the second electrode 9 are opposed to each other with a sealed space formed between the insulating base 1 and the insulating plate 2 interposed therebetween, and the first electrode 7 and the second electrode 9 are interposed between the electrodes. A predetermined capacitance is formed according to the area of the first electrode 7 and the distance between the first electrode 7 and the second electrode 9. And the part which comprises the bottom face 2b of the recessed part of the insulating plate 2 according to the pressure added to the other main surface of the insulating plate 2 from the outside bends to the insulating base | substrate 1, and the space | interval of the 1st electrode 7 and the 2nd electrode 9 As the capacitance changes due to the change in the pressure, it functions as a pressure-sensitive element that senses a change in pressure applied from the outside as a change in capacitance. Further, the change in capacitance is transmitted to the semiconductor element 3 accommodated in the recess 1a via the metallized wiring conductors 5a and 5b, and the magnitude of the pressure applied from the outside is known by performing arithmetic processing in the semiconductor element 3. be able to.

  The first bonding metallization layer 8 and the second bonding metallization layer 10 are made of metal powder metallization of tungsten, molybdenum, copper, silver or the like having a thickness of about 10 to 50 μm, and are similar to the wiring conductor 5 described above. It is formed by the method. It is to be noted that the surfaces of the first bonding metallization layer 8 and the second bonding metallization layer 10 are prevented from being oxidized and corroded, and the first bonding metallization layer 8 and the second bonding metallization layer 10 are bonded to the brazing material. In order to strengthen the thickness, a nickel plating layer having a thickness of about 1 to 10 μm is preferably applied.

  In addition, in the bonding of the insulating substrate 1 and the insulating plate 2, a nickel plating layer having a thickness of about 1 to 10 μm is previously deposited on the surfaces of the first bonding metallization layer 8 and the second bonding metallization layer 10, respectively. In addition, a brazing material foil made of silver-copper brazing having a thickness of about 10 to 200 μm is sandwiched between the first bonding metallization layer 8 and the second bonding metallization layer 10, and these are reduced to about 850 ° C. in a reducing atmosphere. This is performed by melting the brazing material foil by heating to a temperature of 1 mm and brazing the metallized layer 8 for first bonding and the metallized layer 10 for second bonding.

  In the present invention, the insulating plate 2 has a concave portion formed on the inner main surface of the insulating plate 2, and the concave portion has an inner dimension on the bottom surface 2b side larger than an inner dimension on the insulating substrate 1 side. As a result, by forming the bottom surface 2b of the recess of the insulating plate 2 wide, the insulating plate 2 can be made flexible, and external pressure can be detected with high accuracy. By widening and widening the joint between the insulating substrate 1 and the insulating plate 2, the bonding property between the insulating substrate 1 and the insulating plate 2 can be increased, and the internal pressure can be made highly airtight. Therefore, it can be set as the package for pressure detectors which can detect an external pressure accurately.

  Moreover, since the area | region of the bottom face 2b of the recessed part of the insulating plate 2 can be expanded, since the edge part of the bottom face 2b of a recessed part can be kept away from the outer peripheral part of the 2nd electrode 9 formed on the bottom face 2b, the 2nd electrode The outer peripheral portion of 9 also tends to fluctuate well. Therefore, without changing the second electrode 9, the amount of change in capacitance formed by the first electrode 7 and the second electrode 9 can be increased, and the external pressure can be detected with good sensitivity and good sensitivity. It becomes like this.

  Further, it is not necessary to form the insulating plate 2 large, and the pressure detection device package can be formed as a small one.

  The insulating plate 2 of such a pressure detection device package forms through holes having different diameters in at least two ceramic green sheets using, for example, a punching die. And by stacking these, it can be formed as a ceramic green sheet laminate for the protrusion 2a, and it is a through hole that becomes a sealed space in which the opening dimension of one surface and the opening dimension of the other surface are different. Can do. And after printing the conductor paste used as the 2nd electrode, the metallizing layer 10 for 2nd joining, and the wiring conductor 5 to each ceramic green sheet for the projection parts 2a, and the ceramic green sheet for the bottom face 2b by the screen printing method etc., These ceramic green sheets are manufactured by laminating the concave portions so that the inner dimension on the bottom surface 2b side is larger than the inner dimension on the insulating base 1, and after performing a predetermined cutting process, firing at a high temperature. .

  In addition, as shown in the cross-sectional view of the package in FIG. 2, the inner dimension of the recess may be inclined so as to become narrower inward from the bottom surface 2 b side of the recess toward the insulating base 1 side. Accordingly, when the bottom surface 2b of the insulating plate 2 is bent, it is difficult to make contact with the protruding portion 2a, and the difference between the first electrode 7 and the second electrode 9 is easily formed. Therefore, it can be made small and highly sensitive. In such a case, a punching die or the like is used to form a through-hole serving as a sealed space in the ceramic green sheet for the protruding portion 2a so as to spread outward from one main surface to the other main surface. To do. And after printing the conductor paste used as the 2nd electrode, the metallizing layer 10 for 2nd joining, and the wiring conductor 5 on the ceramic green sheet for protrusion 2a, and the ceramic green sheet for bottom face 2b by these screen printing methods etc., these The ceramic green sheets are laminated so that the inner side surface of the through hole serving as a sealed space spreads outward from the bottom surface 2b side toward the side bonded to the insulating base 1, and after performing a predetermined cutting process, Manufactured by firing.

  Thus, according to the package for a pressure detection device of the present invention, the first electrode 7 for forming a capacitance is attached to the other main surface of the insulating substrate 1 on which the semiconductor element 3 is mounted on one main surface. In addition, the inner surface of the insulating plate 2 joined to the insulating substrate 1 in a flexible state so as to form a sealed space with the insulating substrate 1 is covered with the first electrode 7 so as to face the first electrode 7. Since the attached second electrode 9 for forming capacitance is provided, the container for housing the semiconductor element 3 and the pressure sensitive element are integrated, and the pressure detection device can be miniaturized.

  In addition, the first electrode 7 and the second electrode 9 for forming capacitance are connected to the respective electrodes of the semiconductor element 3 via the wiring conductors 5a and 5b disposed on the surface and inside of the insulating base 1. Therefore, the first electrode 7 and the second electrode 9 can be connected to the semiconductor element 3 at a short distance, and as a result, the unnecessary capacitance generated between the wiring conductors 5a and 5b is reduced to a small sensitivity. It is possible to provide a high pressure detection device package.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in FIG. 1, the insulating substrate 1 and the insulating plate 2 are bonded together by a conductive bonding material. After the green sheet for the insulating substrate 1 and the green sheet for the insulating plate 2 are laminated, sintering is performed. It may be integrated. In FIG. 2, the inner dimension of the recess is inclined so as to become narrower inward from the bottom surface 2 b side of the recess toward the insulating base 1 side. A curved surface portion, a right angle portion, or the like may be formed at the boundary and the boundary between the inclined surface and the insulating base 1 so as to have an obtuse angle.

  The present invention can be used for a pressure detection device for detecting a pressure state of a tire or the like.

It is sectional drawing which shows an example of embodiment of the package for pressure detection apparatuses of this invention. It is sectional drawing which shows another example of embodiment of the package for pressure detection apparatuses of this invention. It is sectional drawing of the conventional package for pressure detection apparatuses. It is sectional drawing of the conventional pressure detection apparatus.

Explanation of symbols

1 ·········· Insulation base 1b ····· Mounting portion 2 ··············· Insulation plate 2b ... ..Bottom surface of recess 3 .... Semiconductor element 5, 5a, 5b ... Wiring conductor 7 .... First electrode 9 .... ... Second 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; An insulating plate joined to the insulating base in a flexible state so as to form a sealed space with the other main surface of the insulating base; and the other main surface of the insulating base in the sealed space. A first electrode for forming a capacitance that is attached and electrically connected to one of the wiring conductors, and is attached to the inner main surface of the insulating plate so as to face the first electrode; And a second electrode for forming a capacitance electrically connected to the other one of the wiring conductors, wherein the insulating plate has a recess formed on the inner main surface. The recess has an inner dimension on the bottom side larger than an inner dimension on the insulating base side. Package for pressure detection device, characterized in that it it.

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