JP2012150121A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor capable of easily changing the shape of an introduction pipe without increasing cost.SOLUTION: A pressure sensor is equipped with a sensor chip 1 in which a thin-film diaphragm part 1a and a detection element for detecting deflection caused by the pressure of the diaphragm part 1a are formed and a package 10 comprising an approximately box-shaped body 11 having one open face for storing the sensor chip 1 and an introduction pipe 12 which is mounted on the body 11 and has an introduction port 12a for introducing fluid whose pressure is to be detected into the body 11. The introduction pipe 12 is provided integrally with a flange part 12b projecting toward the outside in the circumferential direction of its one end. The flange part 12b is formed into a circular shape, is locked to the outer peripheral edge of the top edge of the body 11 to block the opening of the body 11, and is mounted on the body 11 by being sealed with a sealing material 6.

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 a body 11 formed in a substantially box shape with one side opening and a cylindrical introduction pipe 12 projecting outward from the center of the bottom surface of the body 11 are integrated. It is formed. The sensor chip 1 is attached to the bottom surface of the body 11 via a glass pedestal (glass pedestal) 9. The glass pedestal 9 is provided with through-holes 9a that are open on both the front and back surfaces. The sensor chip 1 is bonded to the surface of the glass pedestal 9 so as to close the opening on the front side of the through-hole 9a. The back surface of the glass pedestal 9 is bonded to the bottom surface of the body 11 so that the introduction port) 12a communicates with the through hole 9a. 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 8. Here, the sensor chip 1 and the glass pedestal 9 are bonded by anodic bonding, and the glass pedestal 9 and the body 11 are bonded by a silicone-based adhesive (die bonding agent).

JP-A-9-250964

  However, in the above-described conventional example, the body 11 and the introduction pipe 12 are integrally formed. Therefore, in response to the desire to change only the shape of the introduction pipe 12, the body 11 and the introduction pipe 12 are integrated. This requires a mold, which increases the cost.

  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 can easily change the shape of the introduction pipe without increasing the cost.

  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. A substantially box-shaped body having an opening on one side thereof, and a package comprising an introduction pipe attached to the body and having an introduction port for introducing the pressure detection fluid into the body, and the introduction pipe has a peripheral portion at one end thereof. A flange portion protruding outward in the direction is integrally provided, the flange portion is formed in a circular shape, locked to the outer peripheral edge of the end portion where the opening of the body is provided, and the body portion The opening is closed, and it is attached to the body by being sealed with a sealing material.

  According to the present invention, the flange portion of the introduction pipe is locked to the outer peripheral edge of the end portion provided with the opening of the body, and is attached to the body by sealing the flange portion with the sealing material. Since the introduction pipe can be detachably attached to the body, if you only want to change the shape of the introduction pipe, you only need to replace the introduction pipe using a common body, so the body and the introduction pipe are integrated. Therefore, the shape of the introduction pipe can be easily changed without increasing the cost. Further, when sealing the introduction tube to the body with the sealing material, the position of the nozzle for injecting the sealing material can be fixed at one point, and the sealing material can be injected while rotating the introduction tube. Therefore, the sealing material injection operation is facilitated.

It is a figure which shows the pressure sensor of embodiment of this invention, (a) is a top view, (b) is a side view, (c) is a side view seen from the other direction, (d) is a bottom view, (E) is a cross-sectional view taken along line XX ′ with the introduction tube and the body separated. It is a figure which shows an internal structure same as the above, (a) is the top view which abbreviate | omitted the introduction pipe, (b) is a top view which abbreviate | omitted the introduction pipe, the sensor chip, the signal processing part, etc., (c) is principal part sectional drawing. FIG. It is a figure which shows the other structure of a protrusion part same as the above, (a) is a top view which abbreviate | omitted the introduction pipe, the sensor chip, the signal processing part, etc., (b) is an AA 'line cross-sectional view. . It is a top view which abbreviate | omitted the introduction pipe | tube, the sensor chip, the signal processing part, etc. which show other arrangement | positioning of a recessed part same as the above. It is a figure which shows the other structure of a recessed part same as the above, (a) is a top view which abbreviate | omitted the introduction pipe, the sensor chip, the signal processing part, etc., (b) is a BB 'line cross-sectional arrow view, c) is a cross-sectional view taken along the line CC ′. It is a summary explanatory drawing same as the above, (a) is a cross-sectional view of the main part in which an introduction pipe and a body are separated when using an introduction pipe with a small height dimension, and (b) is a case when an introduction pipe with a large height dimension is used. It is principal part sectional drawing which isolate | separated the introduction pipe and the body. It is a figure which shows the other shape of a collar part same as the above, (a) is a top view, (b) is a side view at the time of encapsulating material injection | pouring. It is principal part sectional drawing which shows the other structure of a package same as the above. It is sectional drawing which shows the conventional recess. It is sectional drawing which shows the conventional pressure sensor.

  Hereinafter, embodiments of a pressure sensor according to the present invention will be described with reference to the drawings. However, the same number is attached | subjected about the site | part which is common in a prior art example. Further, in the following description, unless otherwise specified, the vertical and horizontal directions in FIG. As shown in FIGS. 1A to 1E, the present embodiment is a plurality of detection elements that process a semiconductor substrate (silicon substrate) to detect a thin film diaphragm 1a and bending due to pressure of the diaphragm 1a. Sensor chip 1 on which a piezoresistor (not shown) is formed, and a package 10 for housing sensor chip 1.

  The package 10 is a molded product of a synthetic resin material, and as shown in FIG. 1 (e), a body 11 formed in a substantially box shape whose upper surface is open, and an opening of the body 11 is closed and protrudes upward. It consists of a substantially cylindrical introduction tube 12. The body 11 is formed in a substantially rectangular parallelepiped shape that is depressed downward by a predetermined depth, and stores the sensor chip 1 and a signal processing unit 3 (to be described later) into the storage unit 11a. The storage unit 11a faces inward from the inner wall of the storage unit 11a. And a stepped portion 11b. 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 part 11b of the body 11 and the collar part 12b of the introduction pipe 12, as shown in FIG.1 (e), the substantially rectangular flat metal auxiliary plate 4 is arrange | positioned. The auxiliary plate 4 has a peripheral portion of the lower surface thereof placed on the upper surface of the step portion 11b, and a lower surface of the flange portion 12b placed on the upper surface thereof. At this time, the flange portion 12 b is disposed inside the body 11 and closes the opening of the body 11. In this state, by injecting a sealing material 6 such as an epoxy resin from the opening periphery of the body 11, the step portion 11b, the flange portion 12b, and the auxiliary plate 4 are integrally bonded and fixed. In addition, a substantially circular communication hole 4a is provided substantially at the center of the auxiliary plate 4, and a fluid to be pressure-detected flows from the outside into the storage portion 11a via the communication hole 4a. .

  As described above, by arranging the auxiliary plate 4 between the step portion 11 b and the flange portion 12 b, the contact area between the step portion 11 b and the flange portion 12 b can be expanded, and the introduction pipe 12 is attached to the body 11. When the adhesive fixing is performed, the adhesive strength can be increased and the sealing material 6 can be prevented from flowing into the body 11.

  As shown in FIG. 2 (a), the sensor chip 1 is disposed on the lower side of the storage unit 11a in the drawing, and the signal processing unit 3 is disposed on the upper side of the storage unit 11a. The die-bonding agent 2 is applied and fixed to the bottom surface. The die bond agent 2 is formed, for example, by mixing a filler into a silicone resin having high flexibility, and by bonding and fixing the sensor chip 1 and the bottom surface of the storage portion 11a with the die bond agent 2 as described above, the package 10 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.

  An outside air introduction port 11c for allowing air to flow into the body 11 from the outside is provided in a vertical direction at a portion facing the diaphragm portion 1a on the bottom surface of the storage portion 11a. Thus, since the atmosphere flows into the lower part of the diaphragm part 1a from the outside through the outside air inlet 11c, the lower part of the diaphragm part 1a has the pressure and the atmospheric pressure of the pressure detection target fluid flowing in from the inlet 12a. It becomes a pressure reference chamber for comparing.

  Here, in the present embodiment, as shown in FIGS. 2A to 2C, the peripheral edge of the outside air introduction port 11 c on the bottom surface of the storage portion 11 a has a substantially square shape when viewed from the vertical direction protruding upward. 11d is provided integrally with the body 11 over the circumferential direction of the outside air introduction port 11a. Since the die bond agent 2 before curing has flexibility, there is a possibility that the die bond agent 2 flows out from the outside air introduction port 11c. However, by providing the protrusion 11d as described above, the die bond agent 2 opens the outside air introduction port 11c. It can be prevented from flowing out to the outside.

  By the way, considering relaxation of stress to the sensor chip 1, it is preferable that the die bond agent 2 has a large thickness dimension, but it is difficult to confirm whether the die bond agent 2 has a sufficiently large thickness dimension. Therefore, in the present embodiment, the protrusion 11d is used as a means for confirming the thickness dimension of the die bond agent 2. That is, if the sum of the thickness dimension of the sensor chip 1 and the thickness dimension of the die bond agent 2 is smaller than the thickness dimension of the projecting part 11d, the projecting part 11d is brought into contact with the diaphragm part 1a. If the thickness dimension of 11d is set to an appropriate size, it can be easily confirmed whether or not the thickness dimension of the die bond agent 2 is an appropriate dimension. In addition, when the projecting part 11d is in contact with the diaphragm part 1a, the diaphragm part 1a is difficult to bend and a normal detection output cannot be obtained. By confirming whether the detection output is normal, it is possible to confirm whether or not the projecting portion 11d is in contact with the diaphragm portion 1a.

  Further, the shape of the protrusion 11d is not limited to a substantially square shape when viewed from the vertical direction as described above. For example, as illustrated in FIGS. You may comprise in the substantially rectangular shape wide in the left-right direction, ie, a shape substantially similar to the shape of the sensor chip 1. In this case, since the contact area between the sensor chip 1 and the bottom surface of the storage portion 11a is narrowed, the application position of the die bond agent 2 can be determined more precisely, and the required amount of the die bond agent 2 is reduced. Can do. Of course, as long as there is no problem in the application amount of the die bonding agent 2, the shape of the protruding portion 11d may be substantially circular.

  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 (not shown) described later.

  As shown in FIG. 2 (a), a plurality of (four in the figure) long terminals 5 are inserted into the body 11 in such a manner that one end is exposed to the outside of the body 11, as shown in FIG. These terminals 5 are physically and electrically connected to a circuit pattern provided on the external substrate when the sensor is mounted on the external substrate. The plurality of terminals 5 and a plurality of metal pads 3 a provided in the signal processing unit 3 are electrically connected by bonding wires 8 made of metal fine wires, and are provided on the sensor chip 1. A plurality of metal pads 1 b connected to the piezoresistor and a plurality of pads 3 a of the signal processing unit 3 are connected by bonding wires 8.

  Thus, when the diaphragm portion 1a is bent by the pressure of an external fluid flowing into the body 11 from the inlet 12a, the resistance value of the piezoresistor changes, and the output from the piezoresistor according to the change in the resistance value. The signal is processed by the signal processing unit 3, and the processed electrical signal is output to a circuit provided on the external substrate via the terminal 5, thereby detecting the difference between the pressure of the pressure detection target fluid and the atmospheric pressure. It is supposed to be.

  As shown in FIGS. 1 (e) and 2 (c), in a situation where the signal processing unit 3 is connected to the ground by the bonding wire 8, the signal processing unit 3 is connected to the ground of the sensor. By being configured to be mounted directly on the upper surface, the ground of the sensor and the ground of the signal processing unit 3 can be made common, and the electrical characteristics can be further stabilized.

  As shown in FIG. 1 (e), the storage portion 11 a is filled with a JCR (junction coating resin) 7 made of a resin material so as to cover the sensor chip 1 and the signal processing portion 3. 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 is insert-molded can be filled, and the fluid whose pressure is detected leaks to the outside from the gap. Can be prevented.

  As shown in FIG. 1 (d), a recess 11 e communicating with the inside of the body 11 is provided on the lower surface of the body 11. As shown in FIG. 2 (c), the recess 11e has a comb-tooth shape such that its lower end penetrates to the outside of the body 11, and its upper end separates the terminals 5 from each other in the arrangement direction of the terminals 5. Is formed. The recess 11e is formed by a comb-like mold (not shown) that holds the terminal 5 so that the terminal 5 does not move when the body 11 is molded with resin.

  Conventionally, as shown in FIG. 9, when the body 11 is resin-molded, the terminal 5 is pressed by pressing both sides in the thickness direction of each terminal 5 with a rod-shaped mold (not shown) having a substantially conical tip. It was prevented from moving due to pressure during molding. When such a mold is used, there is a possibility that a gap is generated between the terminal 5 and the body 11 and the airtightness cannot be maintained. Therefore, the recess 11f formed by the mold is sealed with a resin or the like. To ensure airtightness. However, since each terminal 5 is disposed at a position away from the center of the body 11, there is a problem that it is difficult to fill the recess 11f with resin or the like.

  On the other hand, in the present embodiment, since each terminal 5 is pressed using the comb-shaped mold as described above, each terminal 5 is covered with the resin material forming the body 11, and thus airtightness is achieved. In addition, since the terminals 5 can be isolated from each other, the movement of the terminals 5 can be prevented and the terminals 5 can be prevented from contacting each other. In addition, as shown in FIG. 4, it is preferable that the recess 11e is arrange | positioned in the front end side in the body 11 of the terminal 5. As shown in FIG. By disposing the recess 11e in this manner, the distal end side of the terminal 5 that is likely to be shaken during resin molding of the body 11 can be pressed, so that the displacement of the terminal 5 can be suitably corrected.

  5A to 5C, a plurality of recesses 11e are provided along the longitudinal direction of the terminal 5 (two in the drawing), and one end penetrates the lower surface side of the body 11. The one end portion may be formed alternately with the one that penetrates to the bottom surface inside the body 11. Since the recess 11e is formed in this way, that is, by alternately pressing from the upper side and the lower side of each terminal 5 with a plurality of comb-shaped dies, the shift in the thickness direction of the terminal 5 can be corrected. The position of the terminal 5 can be further stabilized.

  As described above, the package 10 of the present embodiment has the flange portion 12b disposed inside the body 11 so as to block the opening of the body 11, and the flange portion 12b is sealed with the sealing material 6. Since the introduction pipe 12 is configured to be attached to the body 11, only the introduction pipe 12 can be detachably attached without changing the specification of the body 11. For this reason, for example, the introduction pipe 12 having a small height as shown in FIG. 6A can be replaced with the introduction pipe 12 having a large height as shown in FIG. 6B. Therefore, when it is desired to change only the shape of the introduction tube 12, a new mold in which the body 11 and the introduction tube 12 are integrated is not required, and the shape of the introduction tube 12 can be easily changed without increasing costs. Can do.

  By the way, as another structure of the package 10, as shown in FIG. 8, while making the diameter dimension of the collar part 12b of the introduction pipe 12 larger than the diameter dimension of the body 11, it protrudes below from the outer periphery of the collar part 12b. The structure which locks the collar part 12b to the upper-end outer periphery of the body 11 by integrally forming the latching | locking part 12c to perform is also considered. However, in this configuration, since the sealing material 6 is injected between the locking portion 12c and the body 11 and the flange portion 12b is bonded and fixed to the body 11, the injection state of the sealing material 6 cannot be confirmed. Therefore, there is a risk of causing an airtight defect between the introduction tube 12 and the body 11. Furthermore, when a force is applied to the introduction pipe 12 from the outside, the introduction pipe 12 may be detached from the body 11 depending on variations in the injection amount of the sealing material 6. From the above, the configuration of the package 10 is preferably the configuration of the present embodiment in which the flange portion 12 b is disposed inside the body 11.

  In this embodiment, the shape of the flange portion 12b of the introduction tube 12 is substantially rectangular. However, the shape is not limited to this shape. For example, it is formed in a substantially circular shape as shown in FIG. It doesn't matter. In this case, when sealing the collar portion 12b to the body 11 with the sealing material 6, the position of the nozzle for injecting the sealing material 6 is fixed at one point as shown in FIG. Since the sealing material 6 can be injected while the tube 12 is rotated, there is an advantage that the injection work of the sealing material 6 becomes easy.

  In the present embodiment, the sensor chip 1 is bonded and fixed by applying the die bonding agent 2 to the bottom surface of the storage portion 11a. However, as in the conventional example, the sensor chip 1 is made of a glass base (glass base). You may make it attach to the bottom face of the accommodating part 11a via. Even in this case, similarly to the above, the effect of easily changing the shape of the introduction pipe 12 without increasing the cost can be achieved.

DESCRIPTION OF SYMBOLS 1 Sensor chip 1a Diaphragm part 10 Package 11 Body 12 Introducing pipe 12a Inlet 12b Eave part 6 Sealing material

Claims (1)

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 substantially box-shaped body that opens on one side for housing the sensor chip, and a body are attached to the body. And a package made of an introduction pipe having an introduction port for introducing the pressure detection fluid into the body, and the introduction pipe is integrally provided with a flange portion projecting outward along the circumferential direction of one end thereof. The flange portion is formed in a circular shape, is locked to the outer peripheral edge of the end portion where the opening of the body is provided, closes the opening of the body, and is sealed with a sealing material. A pressure sensor that is attached to a body.

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