JP6156233B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor in which one end side of a sensor chip is sealed with a mold resin and the other end side is exposed to the outside, and a manufacturing method thereof.

  Conventionally, a pressure sensor is known in which one end of a sensor chip is sealed with a mold resin and the other end is exposed to the outside. As this type of pressure sensor, a pressure sensor described in Patent Document 1 is known. This pressure sensor has a configuration in which a sensor chip having a sensing unit on one end side and a circuit chip for controlling the sensor are stacked on the upper surface of the lead frame, and the other end side of the sensor chip is sealed with a mold resin. It is said that. The sensor chip in this pressure sensor has a thin part as a diaphragm that functions as a sensing part for detecting pressure, and a recess for forming the thin part. As described above, in this pressure sensor, the sensing portion having a thin-walled portion is provided on one end side exposed to the outside of the sensor chip, and the pressure medium (air) to the surface of the recess for forming the thin-walled portion is provided. The pressure is detected based on the distortion of the thin-walled portion caused by the pressure of gas such as gas, liquid such as oil, and the like.

JP2012-154801A

  However, in the pressure sensor described in Patent Document 1, water and foreign substances (hereinafter collectively referred to as “objects that obstruct pressure detection”) contained in the pressure medium are formed in a recess for forming a thin portion. It may adhere to the surface. In this case, an error may occur in the ease of distortion of the thin portion due to the pressure of the pressure medium. As a result, the pressure sensor described in Patent Document 1 has a problem in that the pressure detection accuracy decreases.

  In view of the above points, in the pressure sensor in which one end side of the sensor chip is sealed with mold resin and the other end side is exposed to the outside, pressure detection is performed on the surface of the concave portion for forming the thin portion of the sensing portion. An object is to provide a configuration in which an obstacle becomes difficult to adhere.

In order to achieve the above object, in the invention according to claim 1 or 2 , in the pressure sensor, the pressure sensor has one end (2c) and the other end (2d) opposite to the one end and one surface (2a). Sensor chip having a thin-walled portion (21a) as a diaphragm functioning as a sensing portion that performs pressure detection on the side, and a recess (21b) for forming the thin-walled portion formed on one surface on one end side ( 2) In order to prevent objects that obstruct pressure detection from adhering to the surface of the recess, at least the protective part (3) provided on the surface of the recess and the other end of the sensor chip are sealed. a stop for the mold resin (7), and configured to be positioned around the sensor chip so as to be opposed while spaced to one side and the other surface sandwiched by side of the sensor chip (2e) It is, and a fixed frame in the mold resin (9), wherein a protective part, together with the composed protective member formed by gel material, is also provided between the side and the frame of the sensor chip And

  For this reason, it becomes difficult for an object that obstructs pressure detection to adhere to the surface of the recess for forming the thin-walled portion, and an error occurs in the ease of distortion of the thin-walled portion due to the pressure of the pressure medium, resulting in a decrease in pressure detection accuracy. It becomes difficult to occur.

According to a third aspect of the present invention, the sensor chip is configured to be positioned around the sensor chip so as to be opposed to the side surface (2e) sandwiched between one surface and the other surface of the sensor chip with a space therebetween. This is a method for manufacturing a pressure sensor having a frame (9) fixed to a resin, wherein the protective part is composed of a protective member made of a gel material, and is also provided between the side surface of the sensor chip and the frame. Then, arrange the frame so that it faces the side of the sensor chip with a gap and is positioned around the sensor chip, and hang the gel-like protective part between the side of the sensor chip and the frame Thus, a protective portion is provided on the side surface of the sensor chip.

  It also becomes difficult to cause a situation in which an object that obstructs pressure detection adheres to the side surface of the sensor chip and then adheres to the concave portion for forming the thin-walled portion from the side surface to the entire surface.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure which shows the cross-sectional structure of the pressure sensor in 1st Embodiment of this invention. It is a figure which shows the planar structure of the pressure sensor in 2nd Embodiment of this invention. It is a figure which shows the III-III cross section of the pressure sensor shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A pressure sensor 1 according to a first embodiment of the present invention will be described with reference to FIG. The pressure sensor 1 includes a sensor chip 2, a protection unit 3, a circuit chip 4, a bonding wire 5, a lead frame 6, and a mold resin 7. The pressure sensor 1 detects, for example, the pressure of intake air taken into the engine or the pressure of oil that detects exhaust gas pressure in an EGR (Exhaust Gas Recirculation) system and further lubricates each part of the engine. It is used for purposes such as detecting

  As shown in FIG. 1, the sensor chip 2 includes two substrates (hereinafter referred to as a first substrate 21 and a second substrate 22) formed in a flat plate shape using silicon semiconductor, glass, or the like. It is an IC chip formed into a flat plate and having a sensor element and the like formed thereon. The sensor chip 2 typically has a rectangular plate shape whose longitudinal direction is the left-right direction in FIG. The sensor chip 2 is configured to have one surface 2a and another surface 2b opposite to the one surface 2a. Here, as shown in FIG. 1, the first substrate 21 has one surface 2 a and the second substrate 22 has the other surface.

  A sensing unit is provided on the one end 2c side of the one surface 2a of the sensor chip 2. The sensing unit is an element that performs pressure detection, and includes a thin portion 21a as a diaphragm that functions as a sensing portion that performs pressure detection, and a resistor (not shown) is formed in the thin portion 21a. The thin portion 21a has, for example, a thickness of about 10 μm.

  This sensing unit uses the fact that the internal resistance of the resistance changes due to the piezoresistance effect when an external pressure is applied to the thin-walled portion 21a by a pressure medium (a gas such as air or a liquid such as oil). Outputs the corresponding electrical signal. The electrical signal output from the sensor element is sequentially transmitted to the circuit chip 4 and a lead portion 62 of a lead frame 6 described later, and finally transmitted to the outside of the pressure sensor 1.

  The sensing unit is configured to have a concave portion (hereinafter referred to as a first concave portion) 21b having a concave shape with respect to the one surface 2a of the sensor chip 2. Here, the 1st recessed part 21b is comprised as a recessed part formed in order to make the part provided with a diffusion resistance into the thin part 21a among the diaphragms used for a pressure detection. The first recess 21b has a depth of about 250 μm, for example.

  Further, as shown in FIG. 1, in a region facing the first recess 21b on the surface 22a opposite to the surface 2b of the sensor chip 2 of the second substrate 22, a recess (hereinafter referred to as the second substrate 22). 22b) is formed. The pressure reference chamber 8 is formed by the space between the second recess 22 b and the first substrate 21. In the present embodiment, the pressure reference chamber 8 is set to a vacuum pressure, but may be an atmospheric pressure, for example.

  Also, a pad 23 as an electrical connection portion is provided on the other end 2d side of the other surface 2b of the sensor chip 2. The pad 23 is made of aluminum or the like formed by vapor deposition or sputtering.

  The protection part 3 is a member for preventing an object that obstructs pressure detection from adhering to the surface of the first recess 21b, and is provided on the surface of the first recess 21b as shown in FIG. . Here, as an example, the protection unit 3 is provided only on the entire surface of the first recess 21 b of the sensor chip 2.

  Here, the material which comprises the protection part 3 needs to be set according to the kind of pressure medium. That is, for example, when the pressure medium is a gas such as air, the protection unit 3 has a contact angle with a highly water-repellent material, for example, water, of 90 degrees or more, and the sensor chip 2 (first The substrate 21) is made of a material having a larger contact angle with water than the material constituting the substrate 21). When the pressure medium is a gas such as air, water vapor contained in the pressure medium is likely to adhere to the first recess 21b. For this reason, the foreign material mixed in this water vapor tends to adhere to the 1st recessed part 21b. However, in the present embodiment, the provision of the protective portion 3 with high water repellency makes it difficult for water vapor to adhere to the first recess 21b (protecting portion 3), and as a result, foreign matter mixed in the water vapor becomes the first concave portion. It becomes difficult to adhere to 21b. In this case, the protection unit 3 is constituted by a fluorine resin film, a fluorine resin sheet, a fluorine gel, or the like. Here, the protection part 3 is comprised by the film | membrane of the fluorine resin as an example.

  In the case where the pressure sensor 1 is used in an environment where the first recess 21b is exposed to water, the protective unit 3 has a highly hydrophilic material, for example, a contact angle with water of 90 degrees or less, And it is preferable to comprise with the material whose contact angle with water is small compared with the material which comprises the sensor chip 2 (1st board | substrate 21). When the protection unit 3 is made of a highly hydrophilic material, water tends to stay in the protection unit 3, and an object that obstructs pressure detection adheres to the surface of the water remaining in the protection unit 3. Become. Thereafter, the water is washed away together with an object that obstructs pressure detection, so that the object that obstructs pressure detection is easily removed.

  Moreover, it is preferable that the protection part 3 is comprised with the material which is hard to inhibit the distortion of the thin part (diaphragm) 21a. That is, it is preferable that the elastic modulus is low, the thickness is thin, and the material has heat resistance and chemical resistance in an in-vehicle environment. From this viewpoint, as described above, it is particularly preferable that the protection unit 3 is composed of a fluororesin film, a fluororesin sheet, a fluorogel, or the like. It is particularly preferable that the protective part 3 is a thin film having a thickness of several nm. Such a thin film can be produced by a wet process or the like.

  The circuit chip 4 is an IC chip that is formed in a flat plate shape using a silicon semiconductor or the like to form a semiconductor integrated circuit. The circuit chip 4 is electrically connected to the sensor chip 2 and controls pressure detection by the sensor chip 2. As shown in FIG. 1, the circuit chip 4 is disposed so as to face the other end 2 d of the sensor chip 2.

  As shown in FIG. 1, the lead frame 6 has an island part for supporting the sensor chip 2 and the circuit chip 4, and a lead part 62 electrically connected to the circuit chip 4.

  The mold resin 7 is a member that seals a part of the sensor chip 2 on the other end 2 d side, the circuit chip 4, the bonding wire 5, the island part 61, and the lead part 62. The mold resin 7 is made of a general epoxy resin or the like, and is molded by a transfer mold method using a mold or the like.

  The above is the overall configuration of the pressure sensor 1 according to the present embodiment. With the pressure sensor 1 having such a configuration, when the pressure medium passes through the first recess 21b and applies pressure to the sensing portion (thin portion 21a), the pressure of the pressure medium is measured by the sensing portion (thin portion 21a). It can be carried out.

  As described above, the pressure sensor 1 according to the present embodiment is provided on the surface of the first recess 21b in order to prevent an object that obstructs pressure detection from adhering to the surface of the first recess 21b. The protective unit 3 is provided.

  For this reason, it becomes difficult for an object that obstructs pressure detection to adhere to the surface of the first recess 21b, and an error occurs in the ease of distortion of the thin-walled portion due to the pressure of the pressure medium, resulting in a decrease in pressure detection accuracy. It becomes difficult to occur.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the configuration of the protection unit 3 is changed with respect to the first embodiment, and the other aspects are the same as those in the first embodiment, and thus the description thereof is omitted here.

  As shown in FIG. 2 and FIG. 3, in the present embodiment, the sensor chip 2 is opposed to the side surface 2e sandwiched between the one surface 2a and the other surface 2b opposite to the one surface 2a with a space therebetween. A frame 9 configured to be located around the chip 2 is provided. The frame 9 is made of, for example, a resin and is fixed to the mold resin 7. The frame 9 may be formed integrally with the mold resin 7.

  Moreover, the protection part 3 is comprised with the protection member which consists of a gel material. As shown in FIGS. 2 and 3, the protection unit 3 is provided not only on the surface of the first recess 21 b but also between the side surface 2 e of the sensor chip 2 and the frame 9. Here, as an example, the protection unit 3 is provided in the entire region between the side surface 2 e of the sensor chip 2 and the frame 9.

  For this reason, in the pressure sensor 1 according to the present embodiment, an object that becomes an obstacle to pressure detection is attached to the first recess 21b from the side surface 2e to the first surface 2a after being attached to the side surface 2e of the sensor chip 2. Things are less likely to occur.

  Here, the pressure sensor 1 according to the present embodiment is manufactured by the following manufacturing method. Here, only the arrangement of the frame 9 and the production of the protection part 3 which are characteristic parts of the present manufacturing method will be described.

  First, the frame 9 is arranged so as to face the side surface 2e of the sensor chip 2 with a space therebetween and to be positioned around the sensor chip 2. Next, the gel-like protection part 3 is suspended from the one surface 2 a of the sensor chip 2, so that the protection part 3 is placed between the first recess 21 b of the sensor chip 2 and the side surface 2 e of the sensor chip 2 and the frame 9. Provide. At this time, the protective part 3 made of the gel material has fluidity, but remains without falling between the side surface 2e of the sensor chip 2 and the frame 9 due to the surface tension of the gel. In this way, the protection part 3 composed of the protection member made of the gel material is provided in the first recess 21b and the side surface 2e of the sensor chip 2.

  Thus, in this manufacturing method, the protective part 3 having fluidity can be easily provided by the frame 9 having a simple structure.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, in the first embodiment, the protection part 3 is provided only on the entire surface of the first recess 21b. In the second embodiment, the protection part 3 is provided on the entire surface of the first recess 21b and the side surface of the sensor chip 2. It was provided only on the entire surface. However, in the first and second embodiments, the protection unit 3 may be provided on the entire exposed portion of the sensor chip 2 (one surface 2a, side surface 2e, and other surface 2b). In this case, there is also a situation in which an object that obstructs pressure detection adheres to the first recess 21b along the surface of the sensor chip 2 after adhering to a portion other than the first recess 21b in the exposed portion of the sensor chip 2. It becomes difficult to occur. Moreover, you may provide the protection part 3 comprised with the film | membrane and the sheet | seat so that the boundary part of the sensor chip 2 and the mold resin 7 may be covered. In this case, it becomes difficult for the mold resin 7 to peel off from the sensor chip 2 at the boundary between the sensor chip 2 and the mold resin 7.

  In the first and second embodiments, the protection unit 3 is constituted by a fluorine resin film, a fluorine resin sheet, or a fluorine gel. However, the configuration of the protection unit 3 is not limited to this configuration. For example, in the first embodiment, the protective part 3 has a surface with high water repellency or hydrophilicity formed on the one surface 2a of the sensor chip 2 (the surface of the first substrate 21) by a processing technique such as an etching technique or a deposition technique. You may comprise by a part.

2 Sensor chip 21a Thin part 21b 1st recessed part 2
3 Protection part 4 Circuit chip 5 Bonding wire 6 Lead frame 7 Mold resin 9 Frame

Claims (3)

A thin part (21a) as a diaphragm having one end (2c) and the other end (2d) opposite to the one end and having one surface (2a) and functioning as a sensing part for detecting pressure on the one end side And a sensor chip (2) having a configuration in which a recess (21b) for forming the thin portion is formed on the one surface on the one end side,
In order to prevent an object that obstructs pressure detection from adhering to the surface of the concave portion, at least a protective portion (3) provided on the surface of the concave portion,
Mold resin (7) for sealing the other end portion of the sensor chip ;
A frame (9) that is positioned around the sensor chip so as to face the side surface (2e) sandwiched between one surface and the other surface of the sensor chip with a space therebetween, and is fixed to the mold resin. ) And
The pressure sensor according to claim 1, wherein the protection part is formed of a protection member made of a gel material and is also provided between a side surface of the sensor chip and the frame . A circuit chip (4) arranged to face the other end of the sensor chip and controlling pressure detection by the sensor chip;
A bonding wire (5) for electrically connecting the sensor chip and the circuit chip;
An island part (61) for supporting the sensor chip and the circuit chip, and a lead frame (6) having a lead part (62) electrically connected to the circuit chip,
The mold resin is configured to seal a part of the circuit chip, the bonding wire, the island part, and the lead part in addition to a part on the other end side of the sensor chip. The pressure sensor according to claim 1. A method for manufacturing a pressure sensor according to claim 1 or 2 ,
The frame is arranged so as to be opposed to the side surface of the sensor chip while being spaced from the side surface of the sensor chip, and the gel-like protective portion is disposed between the side surface of the sensor chip and the frame. The method for manufacturing a pressure sensor is characterized in that the protective portion is provided on a side surface of the sensor chip by hanging down the sensor.

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