JPH11142266A - Manufacture of pressure detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently weld a sensor chip and a wire by using ultrasonic bonding. SOLUTION: As for the pressure detecting device, in the case where the sensor chip 4 and a circuit board 7 are bonded across a gap 3 by using an ultrasonic wave, a pin 21 is inserted into the pressure intake of a sensing body 2, the tip of the pin 21 is pressed against a step part 2c of the sensing body 2 with a spring 22, and a housing 1 is fixed by a clamp 23 and then fixed tightly. In this fixation state, the sensor chip 4 and circuit board 7 are bonded by a wire 8 with an ultrasonic wave. Therefore, even when the gap 3 is formed between the housing 1 and sensing body 2, resonance of the sensing body 2 at the time of the ultrasonic bonding can be suppressed and the ultrasonic bonding can excellently be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a pressure detecting device for detecting a pressure. It is suitable for use in detection.

[0002]

2. Description of the Related Art Conventionally, as a pressure detecting device of this kind,
Japanese Unexamined Patent Publication No. 62-73131 discloses one.
In this sensor, a sensing body having a thin-walled end portion of a pressure introducing hole is housed in a housing, a displacement of the thin-walled portion is detected by a sensor chip fixed to the thin-walled portion of the sensing body, and an electric current from the sensor chip is detected. The signal is processed by the circuit board. In addition, a gap is formed between the housing and the sensor chip in order to prevent a stress generated when the housing is attached to the detection target from being transmitted to the sensor chip.

[0003]

In the above-described conventional configuration, the circuit board is mounted on the sensing body. However, it is conceivable that this circuit board is fixed to the housing. In this case, the sensor chip and the circuit board are electrically connected by wires across the gap formed between the housing and the sensor chip. Ultrasonic bonding is usually used for this wire connection.

[0004] Then, when the present inventors actually performed ultrasonic bonding in such a configuration, a problem occurred that the sensor chip and the wire were not welded well. After studying this point, since a gap is formed between the housing and the sensor chip,
It has been found that the ultrasonic wave applied to the sensor chip causes the whole sensing body to resonate due to the gap, and that the ultrasonic energy required for welding is not sufficiently transmitted to the sensor chip and the wire.

[0005] The present invention has been made based on the above study,
It is an object of the present invention to be able to satisfactorily weld a sensor chip and a wire using ultrasonic bonding.

[0006]

To achieve the above object, according to the first aspect of the present invention, there is provided a gap between a sensing body (2) and a housing (1) for preventing stress transmission. 3) is formed, and a pressure detecting device is manufactured by connecting a wire (8) toward a surface opposite to a pressure introduction side of a thin portion (2b) formed at the end of the sensing body portion (2). In case, sensing body part (2)
The sensing body part (2) is fixed from the inside of the wire, and in this fixed state, the wire (8) is ultrasonically bonded toward the surface of the thin part (2b) opposite to the pressure introduction side. And

By fixing the sensing body (2) in this manner, resonance of the sensing body (2) during ultrasonic bonding can be suppressed.
The wire (8) can be satisfactorily connected toward the surface of the thin portion (2b) opposite to the pressure introduction side. Further, in the invention according to claim 4, the sensing body part (2)
A gap (3) is formed between the housing and the housing portion (1) to prevent stress transmission, and the sensor chip (4) and the circuit board (7) are electrically connected to each other by wires (8) across the gap (3). When manufacturing the connected pressure detecting device, the sensing body part (2) is inserted from the inside of the sensing body part (2).
Is fixed, and in this fixed state, the sensor chip (4) and the circuit board (7) are ultrasonically bonded by the wire (8).

By fixing the sensing body (2) in this way, resonance of the sensing body (2) during ultrasonic bonding can be suppressed.
The sensor chip (4) and the wire (8) can be welded well. According to the second aspect of the present invention, the ultrasonic bonding of the wire (8) is performed by the sensor chip (4).
According to the third aspect of the present invention, the ultrasonic bonding of the wire (8) is performed on the conductive portion provided on the surface of the thin portion (2b) opposite to the pressure introduction side. Can be performed well on the body.

Further, it is preferable that the sensing body part (2) is fixed so that the resonance frequency of the sensing body part (2) is higher than the vibration frequency used in ultrasonic bonding. Further, a step portion (2c) for reducing the diameter of the pressure introducing hole (2a) on the thin portion (2b) side is formed inside the sensing body portion (2). And fixing members (2
1) may be inserted into the pressure introducing hole (2a), and the tip may be brought into contact with the stepped portion (2c) to fix the sensing body portion (2). Fixing member (21) for fixing housing part (1)
May be pressed in the insertion direction to fix the sensing body (2).

[0010] The reference numerals in parentheses above indicate the correspondence with specific means described in the embodiment described later.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows a cross-sectional structure of a pressure detecting device according to an embodiment of the present invention. This pressure detector is
It measures the pressure of a high-pressure (for example, 20 MPa) fluid such as a fuel pressure of a fuel injection device and a brake oil pressure of a brake device in a vehicle.

In the figure, a housing 1 is made of a metal having good corrosion resistance and weldable (for example, SUS430), has a screw thread 1a, and is screwed to a detection object (not shown) (for example, a fuel pipe). It is fixed. The sensing body 2 is made of a metal having a low coefficient of thermal expansion and a low coefficient of thermal expansion (for example, a material having a linear thermal expansion coefficient close to that of silicon such as Kovar), has a pressure introducing hole 2a on the inside, and a pressure receiving hole 2a at its end. Thin portion 2b forming a diaphragm
Are formed. In addition, a step 2c is formed inside the sensing body 2, and the diameter of the pressure introducing hole 2a is reduced on the side of the thin portion 2b by the step 2c. The step 2c is formed to create a reference plane when the thin portion 2b is machined by cutting.

FIG. 2 shows the appearance of the sensing body 2. The sensing body 2 has a cylindrical shape, and a step portion 2d is formed at an end thereof, that is, a peripheral edge of a lower end opening. The sensing body 2 is press-fitted into the inner cavity of the housing 1, and the step 2d and the housing 1
And the opening edge (end portion) 1b is abutted, and the portion is tightly fixed by electric welding or the like. Thus, the sensing body 2 is assembled and fixed in the housing 1,
A body part is configured.

Further, since the housing 1 has the step 1b formed in the inner cavity of the screw thread 1a, when the sensing body 2 is assembled and fixed in the housing 1, the housing 1 and the sensing body 2 are fixed. Between them, an annular gap 3 is formed. This gap 3 allows the housing 1
Can be prevented from being transmitted to the sensor chip 4 when the sensor is fixed to the object to be detected.

A sensor chip 4 is joined to the upper surface of the thin portion 2b of the sensing body 2, that is, the surface opposite to the pressure introduction side, by a low-melting glass 5 which is an insulator. FIG. 3 shows a cross-sectional perspective view of a tip portion of the sensing body 2. As shown in the figure, four P-type diffusion gauges (strain gauges) 42a are provided on an N-type single crystal silicon substrate 41.
To 42d are formed to form the sensor chip 4, and output an electric signal according to the displacement of the thin portion 2b.

Around the tip of the sensing body 2,
As shown in FIG. 1, a circuit board 7 is arranged. The circuit board 7 has a circuit section such as an amplifier circuit (including an adjustment circuit for adjusting the sensitivity of the sensor) that amplifies and outputs an electric signal from the sensor chip 4, and includes a multilayer ceramic substrate 7a and a circuit chip. 7b and a post 7c.

The multilayer ceramic substrate 7a is formed by printing and baking a conductive paste on the surface and the inner layer, and is fixed to the housing 1 with an adhesive. The circuit chip 7b is mounted on the multilayer ceramic substrate 7a,
The wire is electrically connected to a conductor (a partial region of the wiring) formed by firing the conductive paste of the multilayer ceramic substrate 7a. The post 7c serves as an extraction electrode for making electrical connection with the outside, and is made of, for example, 42 alloy, and is joined to the ceramic laminated substrate 7a by brazing or the like.

The conductor on the surface of the ceramic substrate 7a and the sensor chip 4 are connected to the wire 8 (for example, φ3
(Al wire of 0 to 50 μm). The upper surfaces of the sensing body 2 and the multilayer ceramic substrate 7 (including the upper surface of the sensor chip 4 and the wires 8) are coated with a coating material (for example, silicone gel) 9 to prevent corrosion.

The post 7c joined to the ceramic laminated substrate 7a is connected to the connector terminal 10a of the terminal assembly 10 by electric welding or the like. The terminal assembly 10 includes a connector terminal 10a.
Is insert-molded with a resin such as PPS. The terminal assembly 10 and the connector case 11 formed of a resin such as PPS are caulked and fixed to the housing 1 at the caulking portion 1 d of the housing 1 via an O-ring 12.

The above-described sensor chip 4 and circuit board 7
FIG. 4 shows an electrical connection diagram of the circuit section in FIG. Strain gauge 4
2a to 42d constitute a bridge circuit as shown in the figure. The circuit section on the circuit board 7 includes a power supply circuit 72 for supplying power to the bridge circuit, in addition to an amplifier circuit 71 for amplifying an electric signal from the bridge circuit. The bridge circuit constituted by the strain gauges 42a to 42d outputs an electric signal corresponding to the pressure applied to the thin portion 2b to the amplifier circuit 71, and the amplifier circuit 71 amplifies the signal and responds to the pressure. Outputs an electric signal to the outside.

FIG. 5 is an exploded cross-sectional view of the main parts shown in FIG. 1, and FIGS. 6 to 9 show a process of assembling them and manufacturing a pressure detecting device. 6A to 9B, (a) is a top view, and (b) is a cross-sectional view. [Step in FIG. 6] First, paste-like glass 5 is printed on the sensing body 2 and the sensor chip 4 is joined by firing. Next, the housing 1 is put on the sensing body 2, the sensing body 2 is press-fitted into the housing 1, and the end 1 b of the housing 1 and the step 2 of the sensing body 2
d), and the butted portion is tightly fixed by electric welding or the like. [Step in FIG. 7] Next, an adhesive is thinly and uniformly applied to the upper surface of the housing 1 around the sensing body 2 by a stamp or the like, and the multilayer ceramic substrate 7a on which the circuit chip 7b is mounted is set thereon. Bonding. Then, the conductor of the multilayer ceramic substrate 7a and the sensor chip 4 are electrically connected by ultrasonic bonding using wires 8. Thereafter, coating is performed with the coating material 9. Note that, as shown in FIG. 7, the post 7c includes three posts for a power supply line, an output signal line, and a ground line. [Step in FIG. 8] Next, the connector terminal 10a of the terminal assembly 10 and the post 7a of the multilayer ceramic substrate 7 are aligned and joined by electric welding or the like. [Step in FIG. 9] After that, the connector case 11 and the inside of the housing 1 are sealed and fixed by setting the connector case 11 and the O-ring 12 in the housing 1 and caulking the caulking portion 1d of the housing 1. Thus, the pressure detecting device shown in FIG. 1 is configured.

Next, the step of ultrasonically bonding the sensor chip 4 and the multilayer ceramic substrate 7a with the wires 8 will be described. In performing the ultrasonic bonding, a bonding jig 20 as shown in FIG. 10 is prepared. The jig 20 has a shape for accommodating the housing 1, and has a pin 21 for fixing the sensing body 2 and a hole 20 a for accommodating a spring means (hereinafter referred to as a spring) 22. .

Then, the spring 22, the pin 21, and the housing 1 are set on the jig 20 so that the pin 21 is inserted into the pressure introducing hole 2a of the sensing body 2, and the spring 22 and the pin 21 are located in the hole 20a. Thereafter, the housing 1 is fixed to the jig 20 by a clamp (pressing member) 23.
Fixed to. At this time, since the tip of the pin 21 has a conical shape, the slope portion thereof and the step portion 2c of the sensing body 2 come into contact with each other and press the sensing body 2 upward. As a result, the sensing body 2 is firmly fixed,
The overall rigidity of the sensing body 2 can be increased.

Then, using the bonding tool 24 shown in FIG.
a is ultrasonically bonded with a wire 8. In this ultrasonic bonding, vibration occurs in the direction of the arrow shown in FIG. In this case, the direction of vibration and the direction in which the sensing body 2 is displaced are the same. Therefore, if the sensing body 2 is not fixed as described above, the sensing body 2 is separated by the gap 3 between the housing 1 and the sensing body 2. Although the problem that the whole 2 resonates occurs, when the sensing body 2 is fixed and its rigidity is increased, the resonance frequency of the sensing body 2 can be made sufficiently higher than the driving frequency used in ultrasonic bonding. Therefore, resonance of the sensing body 2 at the time of ultrasonic bonding can be suppressed. Therefore,
The ultrasonic energy can be transmitted to the sensor chip 4 and the wires 8 without loss, and the ultrasonic bonding can be performed well.

The pin 21 may be flattened at its tip to abut the step 2c. In this case, however, the tip of the pin 21 may abut only at one side of the step 2c. Since the resulting pressing force is biased, the pin 21
It is preferable to make the tip of the projection into a protruding shape such as a conical shape or a spherical shape as in the above embodiment. In the above embodiment, the step 21c is pressed upward by the pin 21. However, it is only necessary that the sensing body 2 be mechanically fixed from the inside and reinforced, and for example, as shown in FIG. The pressure introduction hole 2 of the sensing body 2
After being inserted into the sensing body 2, a jig 25 that opens in at least two directions and presses the inner wall of the sensing body 2 may be used. In this case, the jig 25 is driven to open and close using, for example, an air cylinder 26. FIG. 12 (a)
Shows a state in which the jig 25 is closed, and FIG. 12B shows a state in which the jig 25 is opened. Therefore, FIG.
As shown in (b), by opening the jig 25 and pressing the inner wall of the sensing body 2, the sensing body 2 can be fixed.

In the above embodiment, the semiconductor substrate 41
Although the sensor chip 4 is formed by forming the strain gauges 42a to 42d in FIG. 1, the sensor chip may be formed by forming a metal strain gauge on the insulating film by vapor deposition or the like. Further, in the above embodiment, the housing 1 and the sensing body 2 are configured as separate bodies. However, as shown in FIG.
May be integrally configured. In this case, the housing part 1
A gap 3 of an annular groove is formed between the sensor body 2 and the sensing body 2.

In the above-described embodiment, the case where the ceramic substrate 7a and the sensor chip 4 are connected by the wire 8 has been described. However, the present invention is not limited to this, and is within the scope of the present invention. Can be variously modified. For example, the present invention can be applied to a pressure detection device having a configuration in which various circuit portions of the circuit board 7 are integrated with the sensor chip 4 and the multilayer ceramic substrate 7a is omitted. in this case,
A wire used for electrical connection is connected between the sensor chip 4 and the connector terminal 10a or a connector pin (three pins in FIG. 1 which are molded integrally with the connector case 11 and protrude to the outside). Here, when connecting the wires to the sensor chip 4, FIG.
The sensing body 2 is fixed to a bonding jig 20 similar to that shown in FIG. Thereby, the resonance frequency of the sensing body 2 can be made higher than the drive frequency used in ultrasonic bonding, so that resonance of the sensing body 2 during ultrasonic bonding can be suppressed. Therefore, ultrasonic energy can be transmitted to the sensor chip 4 and the wires without loss, and ultrasonic bonding can be performed satisfactorily.

Further, for example, an insulating paste is printed on the upper surface of the thin portion 2b of the sensing body 2, that is, a region other than the mounting region of the sensor chip 4 on the surface opposite to the pressure introducing side, dried, and then subjected to a conductive paste. Print the
The present invention can also be applied to a pressure detection device having a configuration in which the sensor chip 4 is arranged after drying and firing in a batch. In this case, the printing and drying of the insulating paste and the printing and drying of the conductive paste are repeated, and the upper and lower conductive pastes are electrically connected to the conductive paste in the via holes provided in the insulating paste. It may have a structure. Further, a desired circuit section may be formed therein as required. Further, if necessary, a semiconductor layer may be formed on the upper surface of the sensing body 2, and a circuit portion may be formed by introducing impurities or the like.

In this case, the wire connection is made to the sensor chip 4
And the conductor on the sensing body 2, between the sensor chip 4 and the circuit on the sensing body 2, between conductors on the sensing body 2, or between the circuit on the sensing body 2 and the conductor. Connected between them. Note that the conductor in this embodiment is obtained by firing a conductive paste, and indicates a partial region of a wiring.

Here, when connecting the wire to the sensor chip 4 or the conductor or the circuit portion on the sensing body 2, the sensing body 2 is connected to a bonding jig 20 similar to that shown in FIGS. 10 and 12. It is in a fixed state.
Thereby, the resonance frequency of the sensing body 2 can be made higher than the drive frequency used in ultrasonic bonding, so that resonance of the sensing body 2 during ultrasonic bonding can be suppressed. Therefore, the ultrasonic energy is transmitted to the sensor chip 4 and the wire without loss,
Ultrasonic bonding can be performed favorably.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pressure detecting device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an external shape of a sensing body 2. FIG.

FIG. 3 is a partial cross-sectional perspective view showing a configuration of a sensing body 2 and a sensor chip 4.

FIG. 4 is an electrical connection diagram of an amplifier circuit in the sensor chip 4 and the circuit board 7.

FIG. 5 is an exploded sectional view of main components shown in FIG.

FIG. 6 is a diagram showing a step of manufacturing the pressure detecting device shown in FIG.

FIG. 7 is a view showing a step following the step shown in FIG. 6;

FIG. 8 is a view showing a step following the step shown in FIG. 7;

FIG. 9 is a view showing a step following the step shown in FIG. 8;

FIG. 10 shows a jig 20 for bonding the housing 1 to the bonding.
FIG. 3 is a view showing a state in which the sensing body 2 is set with the pin 20 and the spring 22.

FIG. 11 is a diagram showing a state where ultrasonic bonding is performed using a bonding tool 24;

FIG. 12 shows a jig 20 for bonding the housing 1 to the bonding.
FIG. 6 is a view showing a state where the sensor body is fixed using a jig 25 pressing the inner wall of the sensing body 2.

FIG. 13 is a cross-sectional view of a pressure detection device according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 2 ... Sensing body, 2a ... Pressure introduction hole, 2b ... Thin part, 2c ... Step part, 3 ... Gap, 4 ... Sensor chip, 42a-42d ... Strain gauge, 5 ... Low melting point glass, 7 ... Circuit Substrate, 8: Wire, 9: Coating material, 10: Terminal assembly, 10a: Connector terminal, 11: Connector case, 12: O-ring,
Reference numeral 20 denotes a bonding jig, 21 denotes a pin, 22 denotes a spring, 23 denotes a clamp, and 24 denotes a bonding tool.

Claims (8)

[Claims] 1. A sensing body (2) having a pressure introducing hole (2a) inside and a terminating end having a thin portion (2b), and a sensing body outside the sensing body (2) to be detected. A body member (1, 2) having a housing part (1) attached to a body; and an electric signal fixed to a side of the thin part (2b) opposite to a pressure introduction side and corresponding to a displacement of the thin part (2b). And a sensor chip (4) for outputting a stress between the sensing body part (2) and the housing part (1), in order to prevent transmission of a stress different from a pressure due to a detection pressure to the sensor chip (4). Gap (3)
In a method for manufacturing a pressure detecting device, wherein a wire (8) is connected to a surface of the thin portion (2b) opposite to a pressure introduction side, the inside of the sensing body portion (2) is formed. The wire (8) is ultrasonically bonded toward the surface of the thin portion (2b) opposite to the pressure introduction side in this fixed state. Manufacturing method of the detection device. 2. The method according to claim 1, wherein the ultrasonic bonding of the wire is performed on the sensor chip. 3. A conductor is provided on a surface of the thin portion (2b) opposite to the pressure introduction side, and the wire (8)
The method according to claim 1 or 2, wherein the ultrasonic bonding is performed on the conductor. 4. A sensing body part (2) having a pressure introducing hole (2a) inside and a terminal part having a thin part (2b), and a sensing body outside the sensing body part (2) to be detected. A body member (1, 2) having a housing part (1) attached to a body; and an electric signal fixed to a side of the thin part (2b) opposite to a pressure introduction side and corresponding to a displacement of the thin part (2b). A sensor board (7) fixed to the housing portion (1) and electrically connected to the sensor chip (4) to process an electric signal from the sensor chip (4). A gap (3) for preventing stress transmission to the sensor chip (4) is formed between the sensing body part (2) and the housing part (1); ) And the sensor chip (4) In the method for manufacturing a pressure detecting device, wherein the circuit board (7) is electrically connected to the circuit board (7) by a wire (8), the sensing body (2) is fixed from inside the sensing body (2). A method of manufacturing a pressure detecting device, wherein the sensor chip (4) and the circuit board (7) are ultrasonically bonded by wires (8) in the fixed state. 5. The sensing body (2) is fixed so that the resonance frequency of the sensing body (2) is higher than the vibration frequency used in the ultrasonic bonding. The method for manufacturing a pressure detecting device according to any one of the above. 6. A stepped portion (2c) for reducing the diameter of the pressure introducing hole (2a) on the thin portion (2b) side is formed inside the sensing body portion (2), and a fixing member (2) is provided. 21. The sensing body part (2) is fixed by inserting the pressure introducing hole (21) into the pressure introducing hole (2a) and bringing the tip thereof into contact with the step part (2c). A method for manufacturing the pressure detection device according to any one of the first to third aspects. 7. The method for manufacturing a pressure detecting device according to claim 1, wherein the fixing member has a protruding end. 8. The sensing body (2) according to claim 1, wherein the housing (1) is fixed and the fixing member (21) is pressed in the insertion direction to fix the sensing body (2). A method for manufacturing the pressure detecting device according to any one of the above.