JP2000046669A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable pressure sensor free from the breaking of a bonding wire even upon the occurrence of an intermittent temperature change. SOLUTION: In this differential pressure measuring sensor, the whole of a bonding wire 17 for connecting a sensor circuit board 13 and a peripheral circuit element 12, and one end of an Au bonding wire 21 for connecting a pressure detection element 11 and the bonding wire 17 at the side of the peripheral circuit element 12 are covered with the first coating part 16 made of a resin as a coating agent having elasticity, so as to include the whole of the peripheral circuit element 12. In addition, the bonding pad 22 for connecting the other end of the bonding wire 21 is covered with the second coating part 23 coated with the resin as a coating agent having elasticity, so as to have a shape independent of the first coating part 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor such as a differential pressure measuring pressure sensor in which a sensor circuit board on which a pressure detecting element and a peripheral circuit element are mounted is housed in an outer case having a pressure introducing port. .

[0002]

2. Description of the Related Art Conventionally, as this type of pressure sensor, for example, a differential pressure measuring pressure sensor having a structure as shown in FIG. 2 is exemplified. However, FIG. 2A is a side sectional view showing a basic configuration of a differential pressure measuring pressure sensor, and FIG. 2B is a partially enlarged view of a main part of FIG. 2A. is there.

This differential pressure measuring pressure sensor includes a pressure detecting element 11 for detecting a surrounding pressure and outputting a pressure detection signal and a peripheral circuit element 12 for inputting the pressure detection signal and processing the information on a sensor circuit board 13. Mount the sensor circuit board 1
3 is housed and disposed in a lower case 32 having a reference pressure introduction port 31 with a sealant 20 interposed therebetween.
The upper case 34 having the pressure introduction port 33 to be measured is placed on the upper case 34 and hermetically sealed by a hermetic seal. That is, the lower case 32 and the upper case 34 can be regarded as outer cases in which the sensor circuit board 13 is housed and arranged therein.

A pressure introducing hole 14 is formed in the sensor circuit board 13 in advance, and an elastic adhesive 18 having elasticity is applied around the pressure introducing hole 14 so that the pressure detecting element 11 is attached to the pressure introducing hole 14. Placed on top and adhesively fixed. The elastic adhesive 18 absorbs and reduces the influence of the distortion of the sensor circuit board 13 due to the change in the ambient temperature on the pressure detection of the pressure detecting element 11, and can be exemplified by using silicon rubber or the like. . The peripheral circuit element 12 is bonded and fixed on the sensor circuit board 13 with an adhesive 19 such as epoxy. Further, an output lead terminal 15 for outputting a sensor output to the outside through the board circuit pattern is connected to the sensor circuit board 13,
The lead terminals 15 are exposed to the outside through the sealant 20 and the lower case 32.

On the other hand, the bonding pads 22 of the sensor circuit board 13 and the peripheral circuit elements 12 and the pressure detecting elements 11
And the peripheral circuit element 12 are electrically connected to each other by bonding wires 17 and 21 made of Al or Au, respectively.
Bonding wire 17 connected to the peripheral circuit element 1
2 and the bonding wire 21 connecting the pressure detecting element 11 to the entire peripheral circuit element 12 and the pressure detecting element 1
In order to include one bonding pad portion 22, each portion is covered with a coating portion formed by coating with an elastic coating agent to protect each portion. This coating agent is used to avoid and reduce the influence of each part due to a change in ambient temperature, humidity, and the like when detecting the pressure of the pressure detection element 11 and to protect each part. For example, when silicone rubber or the like is used. Can be exemplified.

In the case of this differential pressure measuring pressure sensor, the reference pressure of the reference pressure gas introduced from the reference pressure introduction port 31 of the lower case 32 is applied to the pressure introduction hole 14 of the sensor circuit board 13.
Since the pressure of the gas to be measured introduced through the measured pressure introducing port 33 of the upper case 34 while being applied to the lower surface of the pressure detecting element 11 through the pressure sensor 11 is applied to the upper surface of the pressure detecting element 11, The detection element 11 measures the pressure difference between the pressure of the gas to be measured and the reference pressure of the reference pressure gas, and transmits the detected pressure to the peripheral circuit element 12 through the bonding wire 21 as a pressure detection signal. The peripheral circuit element 12 transmits the result of information processing of the pressure detection signal to the sensor circuit board 13 via the bonding wire 17. The sensor circuit board 13 transmits the processed pressure detection signal to the lead terminal 15 via the board circuit pattern,
Assume sensor output.

[0007]

In the case of the above-described pressure sensor, it is necessary to avoid and mitigate the influence of each part due to changes in ambient temperature, humidity, etc. when detecting the pressure of the pressure detecting element, and to protect each part. The coating part formed by coating with an elastic coating agent such as silicon rubber covers the entire peripheral circuit element including the bonding pad part of the pressure sensing element and the entire bonding wire. When the temperature changes, the coating agent in the coating part expands,
Alternatively, there is a disadvantage that the bonding wire is often cut due to contraction.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a technical problem of the present invention is to provide a highly reliable pressure sensor in which a bonding wire is not broken even if there is an intermittent temperature change. It is in.

[0009]

According to the present invention, a pressure detecting element for detecting a surrounding pressure and outputting a pressure detection signal,
A sensor circuit board mounted with a peripheral circuit element for inputting and processing information by inputting a pressure detection signal is housed and arranged in an outer case having a pressure introduction port, and further, the sensor circuit board and the peripheral circuit element, the pressure detection element, The pressure sensor is connected to the peripheral circuit element by a bonding wire, and the pressure detecting element is adhered and fixed to the sensor circuit board with an elastic adhesive having elasticity. One end of the peripheral circuit element side portion of the connected element and the pressure detecting element and the peripheral circuit element connected thereto are covered with a first coating portion formed by coating with an elastic resin, and Bonding of the pressure detecting element to which the other end of the pressure detecting element and the peripheral circuit element are connected. A pressure sensor comprising covering the pad portion in the second coating section includes a first coating portion formed by coating a resin having elasticity in a separate independent shape can be obtained.

In this pressure sensor, the pressure detecting element is formed by joining a silicon substrate on which a movable electrode deformed by pressure is formed and a glass substrate on which a fixed electrode is formed, with the movable electrode and the fixed electrode facing each other. Preferably, the pressure sensing element is formed by forming a piezoresistive gauge by diffusion on a diaphragm provided on a silicon substrate. In any one of these pressure sensors, it is preferable that at least one of the bonding wires to which the pressure detecting element and the peripheral circuit element are connected is an Au wire.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side sectional view showing a main part of a differential pressure measuring pressure sensor according to an embodiment of the present invention in a partially enlarged manner. However, in the case of this differential pressure measuring pressure sensor as well, FIG.
Since the pressure sensor has substantially the same basic configuration as the conventional pressure sensor described in (a) and (b), the same components will be denoted by the same reference numerals, and description thereof will be omitted, and different portions will be described.

In the case of this differential pressure measuring pressure sensor, FIG.
Compared with the conventional pressure sensor described in (a) and (b), here, the pressure detecting element 11 is formed by a coating agent.
Unlike the structure which covers the whole of the peripheral circuit element 12 and the bonding wires 17 and 21 so as to include the bonding pad portion 22, the sensor circuit board 13 and the peripheral circuit element 1
2 among the bonding wires 17 and 21 connecting the pressure sensing element 11 and the peripheral circuit element 12 respectively, the entire bonding wire 17 connecting the sensor circuit board 13 and the peripheral circuit element 12 and the pressure sensing element 11 and the peripheral circuit element 12 A first coating portion 16 formed by coating one end of the peripheral wire 12 side of the bonding wire 21 connected with the resin with a resin which is a coating agent having elasticity so as to include the entire peripheral wire 12.
And the bonding pad portion 22 of the pressure detecting element 11 to which the other end of the bonding wire 21 is connected.
This is different from the coating portion 16 in that the coating portion is covered with a second coating portion 23 formed by coating with a resin, which is a coating agent having elasticity, in an independent shape. Here, an Au wire is used for at least the bonding wire 21 connecting the peripheral circuit element 12 and the pressure detecting element 11.

In the pressure sensing element 11, a silicon substrate on which a movable electrode deformed by pressure is formed and a glass substrate on which a fixed electrode is formed are joined by opposing the movable electrode and the fixed electrode. Or a configuration in which a piezoresistive gauge is formed by diffusion on a diaphragm provided on a silicon substrate in accordance with existing semiconductor device manufacturing technology (not shown).
May be used.

In the case of this differential pressure measuring pressure sensor, while maintaining the basic performance of performing differential pressure measurement as in the past, the peripheral circuit element 12 in the bonding wire 21 for electrically connecting the pressure detecting element 11 and the peripheral circuit element 12 is provided. One end of the pressure sensing element 11 is covered with the coating portion 16 and the other end of the pressure detecting element 11 connected to the bonding pad portion 22 is covered with the coating portion 23. Stress applied to the bonding wire 21 due to shrinkage (especially at the wire neck) can be sufficiently reduced, and disconnection of the bonding wire 21 due to the stress can be prevented. In addition, since the Au wire is used for the bonding wire 21, corrosion at a portion of the bonding wire 21 that is not covered by the coating portions 16 and 23 can be avoided. Therefore, the differential pressure measurement pressure sensor has basic performance for performing differential pressure measurement as in the related art and has excellent environmental resistance.

[0016]

As described above, according to the pressure sensor of the present invention, the coating of the peripheral circuit element mounted on the sensor circuit board and the coating of the bonding pad portion of the pressure detecting element have independent structures. Therefore, the stress acting on the bonding wire due to the expansion or contraction of the coating agent in the coating part due to the ambient temperature change (especially that of the wire neck part) is reduced,
Breakage of the bonding wire due to a change in ambient temperature can be suppressed. Further, at least one of the bonding wires connected to the pressure detecting element and the peripheral circuit element is an Au wire, and it is possible to prevent the corrosion of the wire in a portion not covered with the coating portion. The sensor has excellent environmental resistance and high reliability.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a main part of a differential pressure measuring pressure sensor according to an embodiment of the present invention in a partially enlarged manner.

FIG. 2 shows a basic configuration of a conventional differential pressure measuring pressure sensor, in which (a) relates to a side sectional view, and (b).
Fig. 8A is a partially enlarged view of a main part of Fig. 9A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Pressure detection element 12 Peripheral circuit element 13 Sensor circuit board 14 Pressure introduction hole 15 Lead terminal 16, 23 Coating part 17, 21 Bonding wire 18 Elastic adhesive 20 Sealant 22 Bonding pad part 31 Reference pressure introduction port 32 Lower case 33 Measured pressure introduction port 34 Upper case

Claims (4)

[Claims] 1. A sensor circuit board on which a pressure detection element for detecting a surrounding pressure and outputting a pressure detection signal, and a peripheral circuit element for inputting the pressure detection signal and processing the information are provided with a pressure introduction port. Stored and deployed in the case,
Further, the sensor circuit board and the peripheral circuit element are connected to the pressure detection element and the peripheral circuit element by bonding wires, respectively, and the pressure detection element is bonded and fixed to the sensor circuit board with an elastic adhesive having elasticity. A pressure sensor connected to at least the sensor circuit board and the peripheral circuit element and one end of the peripheral circuit element side portion of the pressure wire connected to the pressure detection element and the peripheral circuit element. And a bonding pad portion of the pressure detection element to which the other end of the connection of the pressure detection element and the peripheral circuit element is connected. A coating made of a resin having elasticity in an independent shape separately from the first coating portion. A pressure sensor, characterized by comprising covering with a second coating portion formed by. 2. The pressure sensor according to claim 1, wherein the pressure detecting element includes a silicon substrate on which a movable electrode deformed by pressure is formed and a glass substrate on which a fixed electrode is formed. A pressure sensor comprising: 3. The pressure sensor according to claim 1, wherein said pressure detecting element is formed by forming a piezoresistive gauge by diffusion on a diaphragm provided on a silicon substrate. 4. The pressure sensor according to claim 1, wherein at least one of said bonding wires connecting said pressure detecting element and said peripheral circuit element is an Au wire. Pressure sensor.