JPH05164646A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To prevent reduction in accuracy, sensitivity and reliability of a sensor due to thermal stress caused by temperature increase at a packaging location. CONSTITUTION:A title item is provided with a sensor element 32 with a pressure-sensitive diaphragm 31, a bonding wire 37 which connects the sensor element 32 and a hybrid circuit substrate 35, a gel 38 which is thinly applied surface of the sensor element 32 and the bonding wire 37, and a case 39 and a cap 40 which is a casing which is mounted to the hybrid circuit substrate 35 so that it covers a surrounding of the sensor element 32 and the bonding wire 37 and has hole 41 for taking in pressure on an upper surface. Since the gel 38 is thinly applied, the generation of thermal stress can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor pressure sensor for detecting pressure such as intake air pressure, atmospheric pressure or exhaust pressure of an internal combustion engine mounted on an automobile or the like.

[0002]

2. Description of the Related Art In recent years, as automobile exhaust gas regulations have been tightened, it has been required that an automobile engine be always controlled to be in the best combustion state regardless of its operating state.

Therefore, the intake pressure of the engine is detected by using a pressure sensor, and this is converted into an electric signal to electronically control the fuel supply amount, or the ignition timing is controlled so as to maintain an optimum combustion state. Or, the method of detecting the change of the atmospheric pressure and performing the advanced correction has been adopted.

Pressure sensors for automobiles used for such purposes are required to have excellent heat resistance and earthquake resistance.
Semiconductor gauge type pressure sensors have come to be widely adopted as a means for responding to this.

A conventional semiconductor pressure sensor of this type will be described below with reference to FIGS. 5 is a plan view of a conventional semiconductor pressure sensor, FIG. 6 is a sectional view taken along line I-I of FIG. 5, FIG. 7 is a partially cutaway side view of the conventional semiconductor pressure sensor, and FIG. 8 is a conventional semiconductor pressure sensor as an engine controller. FIG. 6 is a partially cutaway side view showing a state in which the same is mounted on a circuit board.

First, in FIGS. 5 and 6, 1 is a pressure-sensitive diaphragm, 2 is a sensor element having the pressure-sensitive diaphragm 1, 3 is a pedestal joined to the sensor element 2 by means of electrostatic bonding, and 4 is a metal. A spacer 5 is a hybrid circuit board, and 6 is an electronic component such as a capacitor mounted on the hybrid circuit board 5. Along with these electronic components 6 and the like, a temperature compensating circuit, an amplifying circuit, a filtering circuit and the like are formed on the hybrid circuit board 5. The metal spacer 4 and the hybrid circuit board 5 are joined by soldering or by means such as an adhesive. 7
Is a bonding wire for connecting an electrode (not shown) formed on the sensor element 2 and the hybrid circuit board 5, and 8 is a gel potted so as to cover the sensor element 2 and the bonding wire 7. Reference numeral 9 denotes a cap mounted on the hybrid circuit board 5 so as to cover the sensor element 2 and the bonding wire 7, and a hole 10 for taking in pressure is formed on the upper surface thereof.

Further, in FIG. 5, reference numeral 11 designates a plurality of lead terminals mounted on the hybrid circuit board 5 for outputting signals from the hybrid circuit board 5. 12
Is a clip portion formed on the base portion of the lead terminals 11 on the hybrid circuit board 5 side for electrically connecting the lead terminals 11 to the hybrid circuit board 5.
Reference numeral 13 denotes a V-cut portion formed at the tip of each lead terminal 11 so as to be easily inserted into an insertion hole of a circuit board such as an engine controller described later. 14 is each lead terminal 11
It is a socket attached to. Of the plurality of lead terminals 11, the f terminal is for grounding (GND), the g terminal is a power input terminal, the h terminal is a sensor output terminal, and the remaining terminals a to e and i to l are characteristic checked. It is a terminal that is inserted into a circuit board such as a power supply terminal and an engine controller to hold the semiconductor pressure sensor.

As shown in FIG. 7, the side surface of the socket 14 is substantially convex, and the upper surface 15 of the socket 14 has the socket 14 mounted on the hybrid circuit board 5.
A taper groove 16 into which a part of the clip portion 12 of the lead terminal 11 is inserted is formed. From the deepest part of the taper groove 16 to the bottom surface 17 of the socket 14, V of the lead terminal 11 is formed.
An insertion hole 18 for inserting the cut portion 13 is formed. In addition, 19 is a coating agent for moisture resistant insulation that is applied so as to cover the flat surface portion of the hybrid circuit board 5 to which the sensor element 2 and the like are joined.

In FIG. 8, reference numeral 20 denotes a circuit board, such as an engine controller, on which the semiconductor pressure sensor is mounted, and a plurality of V-cut portions 13 of the lead terminals 11 exposed from the bottom surface 17 of the socket 14 are inserted therein. An insertion hole 21 is formed. Further, 22 is a solder for joining the circuit board 20 and the V cut portion 13 of the lead terminal 11.

Next, the order of assembling the conventional semiconductor pressure sensor constructed as described above will be described. As shown in FIG. 7, the V-cut portion 13 of the lead terminal 11 is attached to the socket 1
4 is inserted into the insertion hole 18 from the taper groove 16 and the socket 14 is attached to the hybrid circuit board 5, the clip portion 12 of the lead terminal 11 is inserted into the taper groove 16 of the socket 14.
Is in contact with. In this state, the lead terminal 11
The V cut portion 13 is exposed from the bottom surface 17 of the socket 14. When the V cut portion 13 is inserted into the insertion hole 21 of the circuit board 20 such as the engine controller as shown in FIG. 17 contacts the substrate surface of the circuit board 20, and the semiconductor pressure sensor is mounted on the circuit board 20 in a stable state. Next, the V-cut portion 13 of the lead terminal 11 inserted into the insertion hole 21 is joined and fixed on the back surface side of the circuit board 20 with the solder 22, and the mounting of the semiconductor pressure sensor on the circuit board 20 is completed.

[0011]

However, in the above-mentioned conventional configuration, the circuit board 20 such as the engine controller is provided.
When placed in a high temperature environment such as in the engine room, the gel 8 potted to cover the sensor element 2 and the bonding wire 7 thermally expands as the temperature in the engine room rises. However, there is a problem that thermal stress is generated to peel off the bonding wire 7 from the sensor element 2, the accuracy and sensitivity of the sensor element are lowered, and the reliability is lowered.

The present invention is intended to solve such a conventional problem, and reduces the influence of thermal stress on the joint portion between the sensor element and the bonding wire to improve the reliability as an automobile electrical component application. It is an object of the present invention to provide a semiconductor pressure sensor capable of improving the temperature.

[0013]

In order to achieve the above object, the present invention provides a sensor element having a pressure sensitive diaphragm, a bonding wire connecting the sensor element and the hybrid circuit board, and a sensor element and a bonding. A gel coated so as to cover only the surface of the wire thinly, and a casing mounted on the hybrid circuit board so as to cover the periphery of the sensor element and the bonding wire and having a hole for pressure intake on the upper surface. It is a thing.

[0014]

Therefore, according to the present invention, the semiconductor pressure sensor is mounted on a circuit board such as an engine controller,
Even if it is placed in a high temperature place such as an engine room, since the gel is thinly coated only on the surface of the sensor element and the bonding wire, the amount of thermal expansion in this gel is small and the sensor element and the bonding wire It is possible to reduce the influence of thermal stress on the joint portion of, and to prevent the accuracy and sensitivity of the sensor element from decreasing and the reliability from decreasing.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 is a sectional view of the semiconductor pressure sensor according to the embodiment of the present invention taken along the line JJ in FIG. 2, FIG. 2 is a partially cutaway plan view of the semiconductor pressure sensor shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view taken along the line K, and FIG. 4 is a partially cutaway side view showing a state in which the semiconductor pressure sensor in one embodiment of the present invention is mounted on a circuit board such as an engine controller.

First, in FIGS. 1 and 2, 31 is a pressure sensitive diaphragm, 32 is a sensor element having the pressure sensitive diaphragm 31, 33 is a pedestal joined to the sensor element 32 by means such as electrostatic joining, and 34 is a metal. A spacer, 35 is a hybrid circuit board, and 36 is an electronic component such as a capacitor mounted on the hybrid circuit board 35. A temperature compensation circuit, an amplification circuit, a filtering circuit, and the like are formed on the hybrid circuit board 35 together with these electronic components 36 and the like. The metal spacer 34 and the hybrid circuit board 35 are joined by soldering or by means such as an adhesive. Reference numeral 37 is a bonding wire for connecting an electrode (not shown) formed on the sensor element 32 and the hybrid circuit board 35, and 38 is a gel coated so as to thinly cover only the surface of the sensor element 32 and the bonding wire 37. is there. Reference numeral 39 is a case mounted on the hybrid circuit board 35 so as to surround the sensor element 32 and the bonding wire 37, and 40 is a cap mounted on the open upper surface of the case 39, which is a hole for pressure intake. 41 is provided. The case 39 and the cap 40 form a casing.

In FIG. 2, reference numeral 42 denotes a hybrid circuit board 35 mounted on the hybrid circuit board 35.
Is a plurality of lead terminals for outputting signals from.
43 is the hybrid circuit board 3 of these lead terminals 42
It is a clip portion formed on the base portion on the fifth side for mounting each lead terminal 42 on the hybrid circuit board 35.
Reference numeral 44 denotes a V-cut portion formed at the tip of each lead terminal 42 so as to be easily inserted into an insertion hole of a circuit board such as an engine controller described later. Reference numeral 45 is a socket attached to these lead terminals 42. Reference numeral 46 denotes a buckling stress relaxation portion formed on each lead terminal 42 after the socket 45 is mounted on the hybrid circuit board 35. Of these lead terminals 42, the f terminal is for grounding (G
ND), g terminal is a power input terminal, h terminal is a sensor output terminal, and the remaining terminals a to e and i to l are
It is a terminal for characteristic check and a terminal which is inserted into a circuit board such as an engine controller and serves to hold the semiconductor pressure sensor.

The socket 45 includes a pair of side plates 47, 47.
And a top plate 48 that connects the both side plates 47, 47 at the upper part thereof, and the top plate 48 has an insertion hole 49 for inserting the V cut portion 44 of the lead terminal 42. Are formed in plural. In addition, 50 is a coating agent for moisture resistant insulation that is applied so as to cover the flat surface portion of the hybrid circuit board 35 on which the sensor element 32 and the like are mounted.

In FIG. 4, reference numeral 60 denotes a circuit board for an engine controller or the like on which the semiconductor pressure sensor of this embodiment is mounted, and V of the lead terminal 42 exposed from the socket 45.
A plurality of insertion holes 61 into which the cut portions 44 are inserted are formed. Further, 62 is a solder for joining the circuit board 60 and the V cut portion 44 of the lead terminal 42.

Next, the order of assembling the semiconductor pressure sensor of this embodiment having the above structure will be described. First, as shown in FIG. 3, the V cut portion 44 of the lead terminal 42 is inserted into the insertion hole 49 formed in the top plate 48 of the socket 45,
The socket 45 is attached to the hybrid circuit board 35.
At this point, the lead terminal 42 is linear.
Next, the lead terminal 42 exposed from the bottom of the socket 45
Then, the buckling-shaped stress relaxation portion 46 is formed by using any means. Then, when the V cut portion 44 of the lead terminal 42 on which the stress relaxation portion 46 is formed is inserted into the insertion hole 61 of the circuit board 60 such as an engine controller as shown in FIG. 4, the bottom portion of the socket 45 is placed on the circuit board 60. The semiconductor pressure sensor is mounted on the circuit board 60 in a stable state by contacting the surface of the board. Next, the V cut portion 44 of the lead terminal 42 inserted into the insertion hole 61 is joined and fixed to the rear surface side of the circuit board 60 with the solder 62, and the mounting of the semiconductor pressure sensor on the circuit board 60 is completed.

By the way, when the semiconductor pressure sensor is mounted on the circuit board 60 and arranged in the engine room, the temperature of the engine room increases and the temperature of the sensor element 32 and the bonding wire 37 increases due to the temperature increase. Thermal expansion also occurs in the gel 38 coated on the gel 38. However, in the present embodiment, the gel 38 is coated so as to cover only the surfaces of the sensor element 32 and the bonding wire 37 thinly, so that the thermal expansion of the gel 38 occurs. The amount is small, the influence of thermal stress on the bonding portion between the sensor element 32 and the bonding wire 37 is reduced, and it is possible to prevent the accuracy and sensitivity of the sensor element 32 from decreasing and the reliability from decreasing.

[0022]

As described above, according to the present invention, the gel is thinly coated only on the surface of the sensor element having the pressure sensitive diaphragm and the bonding wire connecting the sensor element to the hybrid circuit board. Since the coating is applied, this semiconductor pressure sensor is mounted on a circuit board such as an engine controller, and even if it is placed in a high temperature place such as in the engine room, the amount of thermal expansion in the gel is small, and the sensor element and the bonding wire It is possible to reduce the influence of thermal stress on the joint, and to prevent the accuracy and sensitivity of the sensor element from decreasing and the reliability from decreasing.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor pressure sensor according to an embodiment of the present invention taken along the line JJ of FIG.

FIG. 2 is a partially cutaway plan view of the semiconductor pressure sensor shown in FIG.

FIG. 3 is a sectional view taken along the line KK of FIG.

FIG. 4 is a partially cutaway side view showing a state in which a semiconductor pressure sensor according to an embodiment of the present invention is mounted on a circuit board such as an engine controller.

FIG. 5 is a plan view of a conventional semiconductor pressure sensor.

6 is a sectional view taken along line I-I of FIG.

FIG. 7 is a partially cutaway side view of a conventional semiconductor pressure sensor.

FIG. 8 is a partially cutaway side view showing a conventional semiconductor pressure sensor mounted on a circuit board such as an engine controller.

[Explanation of symbols]

 31 Pressure Sensitive Diaphragm 32 Sensor Element 35 Hybrid Circuit Board 37 Bonding Wire 38 Thinly Coated Gel 39 Case 40 Cap 41 Hole for Pressure Intake

Claims (1)

[Claims] 1. A sensor element having a pressure-sensitive diaphragm, a bonding wire connecting the sensor element and a hybrid circuit board, and a gel coated so as to thinly cover only the surface of the sensor element and the bonding wire. A semiconductor pressure sensor, comprising: a casing mounted on the hybrid circuit board so as to cover the periphery of the sensor element and the bonding wire and having a hole for pressure intake on an upper surface thereof.