JP2008082969A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor for eliminating an effect on the detection precision due to a fluctuation in a pressure even if a stress is applied due to an externally-applied force. <P>SOLUTION: The pressure sensor is provided with: a sensor chip 1 having a thin film diaphragm 1a, and a piezoelectric resistor for detecting a bend due to the pressure from the diaphragm 1a by processing a semiconductor substrate; a body 11 for accommodating with the sensor chip 1; a package 10 comprising an introduction pipe 12 attached to the body 11, and having an introduction opening 12a for introducing a fluid whose pressure is detected into the body 11; and a glass seat 2 for fixing the sensor chip 1 on an upper face and fixing the body 11 on a lower face. The sensor chip 1 and the glass seat 2 are attached and fixed by a fixing member. The glass seat 2 and the body 11 are attached and fixed by the fixing member comprising a silicone resin containing a mixture of a fine solid material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure sensor that detects the pressure of a fluid such as a gas.

Conventionally, a pressure sensor (semiconductor pressure sensor) that utilizes the properties of silicon as an excellent elastic body and forms a thin film part called a diaphragm part on a silicon substrate by micromachining technology to convert pressure changes into electrical signals. ) Is provided (see, for example, Patent Document 1). An example of this type of semiconductor pressure sensor is shown in FIG. This conventional example includes a sensor chip 1 in which a semiconductor substrate (silicon substrate) is processed to form a thin film diaphragm 1a and a piezoresistor (not shown) which is a detection element for detecting deflection due to the pressure of the diaphragm 1a. And a package 10 for housing the sensor chip 1. The package 10 is a molded product of a synthetic resin material, and has a body 11 formed in a substantially box shape whose one surface is open, and a cylindrical shape that protrudes outward (downward in FIG. 3) from the center of the bottom surface of the body 11. The introduction pipe 12 is integrally formed. The sensor chip 1 is attached to the bottom surface of the body 11 via a glass pedestal (glass pedestal) 2. The glass pedestal 2 is provided with through holes 2a that are open on both the front and back surfaces, and the sensor chip 1 is bonded to the surface of the glass pedestal 2 (the upper surface in FIG. 3) so as to close the opening on the front side of the through hole 2a. The back surface (the lower surface in FIG. 3) of the glass pedestal 2 is bonded to the bottom surface of the body 11 so that the opening (introduction port) of the introduction tube 12 communicates with the through hole 2 a. A plurality of terminals 5 are inserted into the body 11, and the plurality of terminals 5 and the piezoresistors of the sensor chip 1 are electrically connected by bonding wires 14. Here, the sensor chip 1 and the glass pedestal 2 are bonded by anodic bonding, and the glass pedestal 2 and the package 10 are bonded by a silicone-based adhesive (die bonding agent) 13.
JP-A-9-250964

  By the way, in the pressure sensor as described above, it is necessary to increase the sensitivity of the sensor chip 1 as the pressure to be detected becomes lower. However, when the sensitivity of the sensor chip 1 is increased, the stress in the sensor chip 1 is caused by the stress of the force applied from the outside. Since the detection accuracy is lowered, there is a problem that the influence of the external stress must be reduced.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a pressure sensor that does not affect the detection accuracy of a pressure change even when an external force is applied.

  In order to achieve the above object, the invention according to claim 1 houses a sensor chip in which a semiconductor substrate is processed to form a thin film diaphragm portion and a detection element for detecting a deflection due to pressure of the diaphragm portion, and the sensor chip is accommodated. And a package comprising an introduction pipe having an introduction port for introducing a pressure detection fluid to the inside of the body attached to the body, and mitigating the stress applied from the outside applied to the package to the sensor chip Means is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the sensor chip is fixed to one surface and the other surface is fixed to the body, and the relaxing means includes the pedestal and the sensor chip, and the pedestal and the body. And a base member and a sensor chip, and a base member and a body. The fixing member is made of a resin mixed with a fine solid material.

  According to a third aspect of the present invention, in the first aspect of the present invention, the relaxing means is a fixing member that is interposed between the sensor chip and the body and adheres and fixes the sensor chip and the body, and the fixing member is flexible. It consists of the adhesive which has.

  According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the body is provided with a housing portion in which the sensor chip is housed, and a front end surface of the introduction pipe mounted from the inner wall of the housing portion. And an auxiliary plate having an area larger than the contact area between the introduction tube and the step portion is interposed between the introduction tube and the step portion.

  According to a fifth aspect of the present invention, in the invention of the fourth aspect, the step portion has a protrusion protruding in a direction toward the introduction pipe and the auxiliary plate, and the auxiliary plate has an insertion hole for inserting the protrusion. And the introduction pipe has a fitting recess into which the protrusion is fitted.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the body includes a terminal that is led out and electrically connected to the detection element of the sensor chip. The sensor chip is sealed with a resin material.

  A seventh aspect of the invention is characterized in that, in the sixth aspect of the invention, a plurality of terminals are led out to the outside of the body, and any one of the terminals has a mark at a portion protruding to the outside of the body.

  According to the first aspect of the present invention, by providing the relaxation means for relaxing the stress of the force applied from the outside applied to the package to the sensor chip, the pressure change in the sensor chip can be reduced even when the stress of the force applied from the outside is applied. The detection accuracy can be prevented from being affected.

  According to the invention of claim 2, by providing the pedestal, it is possible to relieve the stress of the force applied from the outside applied to the package from being transmitted to the sensor chip. In addition, by fixing the base and sensor chip, and the base and the body with a fixing member made of resin mixed with fine solids, the thickness of the fixing member can be made uniform, and the ambient temperature changes. On the other hand, since the fixing member is uniformly deformed, the stress on the sensor chip due to the biasing of the fixing member can be reduced. Furthermore, since the resin mixed with fine solids has a smaller coefficient of linear expansion than that of the resin alone, the amount of deformation of the fixing member can be reduced.

  According to the invention of claim 3, since the sensor chip and the body are fixed by the flexible adhesive, it is possible to relieve the stress of the force applied from the outside applied to the package from being transmitted to the sensor chip.

  According to the invention of claim 4, the contact area between the introduction pipe and the body is reduced by interposing an auxiliary plate having an area larger than the contact area between the introduction pipe and the step part between the introduction pipe and the step part. It is possible to widen and increase the adhesive strength when adhering the introduction tube to the body and to prevent the adhesive from flowing into the body.

  According to the fifth aspect of the present invention, the body and the introduction tube can be easily positioned by inserting the protrusion of the step portion into the insertion hole of the auxiliary plate and fitting it into the fitting recess of the introduction tube. Moreover, since the adhesive flows into the insertion hole and the fitting recess when the introduction tube is bonded to the body, the bonding effect can be enhanced.

  According to the invention of claim 6, by sealing the terminal and the sensor chip with the resin material inside the body, it is possible to prevent the fluid from leaking from the portion of the body where the terminal is led out.

  According to the seventh aspect of the present invention, by providing a mark on any of the terminals, it is possible to easily determine the connection location between each terminal and the substrate when the pressure sensor is mounted on the substrate or the like.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, parts that are the same as those in the conventional example are given the same reference numerals. Moreover, in the following description, unless otherwise specified, the vertical and horizontal directions in FIG. In the present embodiment, as shown in FIG. 1A, a semiconductor substrate (silicon substrate) is processed to detect a thin film diaphragm 1a and a plurality of piezoresistors (detecting elements that detect bending due to pressure of the diaphragm 1a). A sensor chip 1 on which a sensor chip 1 is formed, and a package 10 that houses the sensor chip 1.

  The package 10 is a molded product of a synthetic resin material, and includes a body 11 formed in a substantially box shape whose one surface is open, and a cylindrical introduction pipe 12 which closes the opening of the body 11 and protrudes upward. . The body 11 is formed in a substantially rectangular parallelepiped shape that is depressed by a predetermined depth in the downward direction, a storage portion 11a in which the sensor chip 1 and a signal processing unit 3 to be described later are stored, and an inner wall of the storage portion 11a toward the inside. On the right side of the storage portion 11a, a recessed portion 11d that is recessed downward by a predetermined depth is formed, and a glass pedestal (glass pedestal) is formed on the bottom surface of the recessed portion 11d. ) 2 is disposed. The introduction pipe 12 is provided with an introduction port 12a that penetrates in the vertical direction and guides the fluid to be detected from the outside to the inside of the body 11, and the introduction pipe 12 has a substantially rectangular shape projecting outward at the peripheral edge of the lower end portion. The shaped flange 12b is integrally formed over the entire circumference.

  Between the step portion 11b of the body 11 and the flange portion 12b of the introduction pipe 12, a metal auxiliary plate 4 having a substantially rectangular flat plate shape is disposed. In the auxiliary plate 4, the peripheral edge portion of the lower surface is placed on the upper surface of the step portion 11 b of the body 11, and the lower surface of the flange portion 12 b of the introduction pipe 12 is placed on the upper surface of the auxiliary plate 4. In this state, by injecting the adhesive 6 from the peripheral edge of the opening of the body 11, the stepped portion 11 b of the body 11, the flange portion 12 b of the introduction tube 12, and the auxiliary plate 4 are integrally bonded and fixed. Further, a substantially circular communication hole 4a is provided substantially at the center of the auxiliary plate 4, so that the fluid to be pressure-detected flows from the outside into the housing portion 11a of the body 11 through the communication hole 4a. It has become. Further, as shown in FIG. 1B, a total of four notches 4b (two in the drawing) are provided on each of the left and right sides of the auxiliary plate 4 in the figure. These notches 4b are fitted into the protrusions 11c provided on the upper surface of the step portion 11b of the body 11, and the fitting recesses (shown in the figure) on the lower surface of the flange portion 12b of the introduction pipe 12 corresponding to the protrusions 11c. The body 11 and the introduction pipe 12 can be easily positioned by fitting the projection 11c protruding above the auxiliary plate 4 into the projection 11c.

  As described above, the auxiliary plate 4 is disposed between the step portion 11b of the body 11 and the flange portion 12b of the introduction tube 12, so that the contact area between the flange portion 12b of the introduction tube 12 and the step portion 11b of the body 11 is increased. The adhesive strength can be increased when the introduction tube 12 is bonded to the body 11, and the adhesive 6 can be prevented from flowing into the body 11.

  The glass pedestal 2 is formed in a substantially rectangular parallelepiped shape, and a through hole 2a that is open on both the upper and lower surfaces is provided in the approximate center thereof. The lower surface of the glass pedestal 2 is connected to the bottom surface of the concave portion 11d so that the outside air inlet 11e and the through hole 2a communicated with and fixed to the upper surface by a fixing member (not shown) which will be described later and penetrated through the bottom surface of the concave portion 11d It is bonded and fixed by a fixing member. Accordingly, the atmosphere flows into the lower part of the diaphragm part 1a from the outside through the outside air inlet 11e and the through hole 2a. Therefore, the lower part of the diaphragm part 1a has the pressure of the fluid to be detected and the atmospheric pressure flowing from the inlet 12a. It becomes a pressure reference chamber for comparing with.

  The signal processing unit 3 includes a substantially rectangular IC chip, and includes an amplifier circuit that amplifies an output signal of a circuit including a piezoresistor of the sensor chip 1 and an adjustment resistor that adjusts an output of the amplifier circuit. A circuit is formed. In this signal processing circuit, the output signal from the sensor chip 1 is appropriately processed and output to an external substrate described later.

  As shown in FIG. 1B, the body 11 has a plurality of (four in the figure) terminals 5 inserted in the left and right outer walls, respectively, and these terminals 5 are external boards (not shown). When a sensor is mounted on the circuit pattern, it is physically and electrically connected to a circuit pattern provided on an external substrate. The plurality of terminals 5 and the signal processing unit 3 are electrically connected by bonding wires (not shown), and the piezoresistor of the sensor chip 1 and the signal processing unit 3 are electrically connected by bonding wires. Has been. Therefore, when the diaphragm portion 1a bends due to the pressure of an external fluid flowing into the body 11 from the introduction port 12a, the resistance value of the piezoresistor changes, and an output signal from the piezoresistor corresponding to the change in the resistance value is a signal. The electric signal processed and processed by the processing unit 3 is output to a circuit provided on the external substrate via the terminal 5 so as to detect the difference between the pressure of the pressure detection target fluid and the atmospheric pressure. It has become. The signal processing unit 3 may be directly mounted on the terminal 5 inside the body 11 without being connected to the terminal 5 with a bonding wire.

  Further, as shown in FIG. 1B, a substantially rectangular protrusion 5a protruding downward is integrally formed on the upper left terminal 5 in the figure. By providing such a protrusion 5a, when the present embodiment is mounted on an external substrate, the protrusion 5a serves as a mark, and the correspondence between each terminal 5 and a connection portion (not shown) of the external substrate can be achieved. It can be easily distinguished. The shape and arrangement of the protrusions 5a are not limited to the present embodiment, and other shapes and arrangements may be used.

  As shown in FIG. 1A, the housing 11 a of the body 11 is filled with a JCR (junction coating resin) 7 made of a resin material so as to cover the sensor chip 1, the glass pedestal 2, and the signal processing unit 3. Yes. By filling the JCR 7 in this way, the sensor chip 1 and the signal processing unit 3 can be protected, and the gap of the part where the terminal 5 of the body 11 is inserted can be filled, and the fluid whose pressure is to be detected is exposed to the outside through the gap. Leakage can be prevented.

  In the present embodiment, the sensor chip 1 and the glass pedestal 2, and the fixing member for bonding and fixing the glass pedestal 2 and the recess 11d of the body 11 are characterized. The fixing member is a silica-based resin die bond agent. It is made by mixing fine solids such as alumina. In this way, by mixing a fine solid in the die bond agent, the thickness of the fixing member can be made uniform as compared with the case where it is not mixed. Therefore, since the fixing member is uniformly deformed when the ambient temperature is changed and the fixing member is deformed, the die bond agent is not irregularly distorted, so that the stress applied to the sensor chip 1 can be reduced. it can. In addition, when a fine solid is mixed in the fixing member as described above, the linear expansion coefficient can be reduced compared to the case where the fixing member is formed of a single silicone resin, so the deformation amount of the fixing member is reduced. Therefore, it is possible to reduce the transmission of the stress of the force applied from the outside of the package 10 to the sensor chip 1.

  As described above, the fixing members for bonding and fixing the sensor chip 1 and the glass pedestal 2 and the glass pedestal 2 and the body 11 are configured by mixing fine solids in the silicone-based resin. The stress transmitted to the sensor chip 1 by the applied force can be relaxed, and the detection accuracy of the pressure change in the sensor chip 1 can be prevented from being affected.

(Embodiment 2)
Embodiment 2 of the present invention will be described below with reference to the drawings. However, parts that are the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the present embodiment, as shown in FIG. 2, the sensor chip 1 and the concave portion 11d of the body 11 are bonded and fixed with a die bonding agent 8 as a fixing member without providing the glass pedestal 2. The die bond agent 8 is formed, for example, by mixing a filler into a silicone resin having high flexibility, and the package 10 is obtained by bonding and fixing the sensor chip 1 and the concave portion 11d of the body 11 with the die bond agent 8 as described above. It is possible to relieve the stress of the force applied from the outside of the sensor chip 1 from being transmitted to the sensor chip 1.

It is a figure which shows the pressure sensor of Embodiment 1 of this invention, (a) is sectional drawing, (b) is the partial perspective view seen from the upper side. It is sectional drawing which shows a part of pressure sensor of Embodiment 2 of this invention. It is sectional drawing which shows the conventional pressure sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor chip 1a Diaphragm part 2 Glass base 10 Package 11 Body 12 Introducing pipe 12a Inlet

Claims (7)

  A sensor chip on which a semiconductor substrate is processed to form a thin film diaphragm portion and a detection element for detecting deflection due to the pressure of the diaphragm portion, a body housing the sensor chip, and a pressure sensing fluid attached to the body inside the body A pressure sensor comprising: a package comprising an introduction pipe having an introduction port for introduction into the sensor; and a relaxation means for mitigating transmission of stress from an external force applied to the package to the sensor chip.   The sensor chip is fixed to one surface and the other surface is fixed to the body, and the relaxation means is interposed between the base and the sensor chip and between the base and the body, and the base, the sensor chip, and the base The pressure sensor according to claim 1, wherein the fixing member is made of a resin mixed with a fine solid material.   2. The relaxation means is a fixing member that is interposed between the sensor chip and the body to bond and fix the sensor chip and the body, and the fixing member is made of a flexible adhesive. The described pressure sensor.   The body has a storage portion in which the sensor chip is stored, and a step portion that protrudes from the inner wall of the storage portion and on which the leading end surface of the introduction tube is placed, and is introduced between the introduction tube and the step portion. The pressure sensor according to any one of claims 1 to 3, wherein an auxiliary plate having an area larger than a contact area between the pipe and the step portion is interposed.   The step portion has a protrusion protruding in a direction toward the introduction pipe and the auxiliary plate, the auxiliary plate has an insertion hole for inserting the protrusion, and the introduction pipe is fitted with the protrusion. The pressure sensor according to claim 4, further comprising a fitting recess.   6. The body according to claim 1, wherein the body includes a terminal that is led out and electrically connected to a detection element of the sensor chip, and the terminal and the sensor chip are sealed with a resin material inside the body. The pressure sensor according to any one of claims.   The pressure sensor according to claim 6, wherein a plurality of the terminals are led out to the outside of the body, and any one of the terminals has a mark at a portion protruding to the outside of the body.

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