JPS63175736A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE:To protect a semiconductor strain gauge from a harmful body by structuring an intake for pressure to be measured that members holed shifting in center from each other are inserted into the pressure intake from both sides without aligning both holes with each other while a space is formed in the middle. CONSTITUTION:The pressure intake 12 is formed in a 2nd casing 8 and the members 15 and 16 which are holed shifting in center from each other are inserted into the pressure intake 12 bored in a 2nd casing 8 without aligning the holes 13 and 14 with each other so that the space is formed in the middle, thus forming the intake for pressure to be measured. Further, a taper 17 is provided on the measured pressure intake of the casing 8 on the side of a measurement chamber. When the pressure Pi to be measured is applied, the vapor of gasoline contained in medium whose pressure is to be measured strikes on the member 15 first in the case of entering the inside through the hole 14 of the member 16 and then enters the pressure measurement chamber through the hole 13, so the vapor is liquefied and hard to enter the pressure chamber and it is easily discharged by liquefying of the vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor pressure sensor, and particularly to a semiconductor pressure sensor suitable as a pressure sensor for an automobile.

[Conventional technology]

The conventional semiconductor pressure sensor is disclosed in Japanese Patent Application Laid-open No. 55-13756.
As described in Publication No. 4, the pressure to be measured inlet had a straight structure. Figure 4 is a structural diagram of a conventional semiconductor pressure sensor, in which 1 is a first casing, 2 is a semiconductor strain gauge support, and at the tip of this is a silicon chip 3 whose U-shaped bottom is processed into a diaphragm shape. and fix it to support stand 2.
A vacuum chamber is formed between the silicon chip 3 and the silicon chip 3, a semiconductor strain gauge is formed on the lower surface of the diaphragm of the silicon chip 3, and its surface is protected with a protective material 4. Reference numeral 5 indicates an adhesive that fixes the support base 2 to the first casing 1, and reference numeral 6 indicates a terminal for transmitting an output signal of the semiconductor strain gauge connected to the semiconductor strain gauge by a metal wire 7 to the outside. A second casing 8 is fixed to the first casing 1 at a lower part thereof through a joint 9, and a pressure to be measured inlet 10 having a straight structure is provided at the lower part of the semiconductor strain gauge. A measurement pressure Ps is applied to the semiconductor strain gauge. In the semiconductor pressure sensor having the structure shown in FIG. 4, the pressure to be measured P is as follows because the pressure inlet 10 has a straight structure.
Liquefied or vaporized substances such as gasoline contained in the pressure medium to be measured easily enter the pressure measurement chamber. Further, if liquefied substances enter, the liquefied substances tend to accumulate in the corner 11 inside the casing 8, and this is particularly likely to occur when the semiconductor pressure sensor is installed diagonally with respect to the ground.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology has a problem in that liquefied or vaporized substances such as gasoline contained in the pressure medium to be measured easily enter the pressure measurement chamber, resulting in deterioration of the characteristics of the semiconductor strain gauge.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor pressure sensor that can protect a semiconductor strain gauge and an adhesive at a joint from liquefied and vaporized substances such as gasoline contained in a pressure medium to be measured.

[Means for solving problems]

The above object is achieved by making the structure of the pressure inlet to be measured provided in the second casing into a labyrinth shape, and by making the end shape into a taper.

[Effect]

By forming the measurement pressure inlet of the semiconductor pressure sensor into a labyrinth shape, the liquefied substance contained in the pressure medium to be measured is difficult to enter into the pressure measurement chamber, and the process of passing through the pressure introduction port is prevented. In this case, the probability that the pressure medium will come into contact with the wall surface increases, and the vaporized material becomes easier to liquefy, and can be released to the outside as a liquid. Furthermore, since the end of the pressure introduction port on the pressure measurement chamber side is tapered, the liquid that accumulates inside the casing can easily come out.

〔Example〕

The present invention will be explained in detail below using the embodiments shown in FIGS. 1 to 3.

FIG. 1 is a structural diagram showing an embodiment of the semiconductor pressure sensor of the present invention. In Figure 1, 1 is a first casing, 2 is a semiconductor strain gauge support, 3 is a silicon chip whose U-shaped bottom is processed into a diaphragm shape, and a semiconductor strain gauge is formed on the bottom surface, and 4 is a protection 5 is the adhesive that fixes the support base 2 to the first casing 1; 6 is the terminal;
7 is a metal wire, 8 is a 20th casing, and 9 is a joint between the first casing 1 and the second casing 8, which are the same as in the conventional case. By the way, in the embodiment shown in FIG. 1, the shape of the pressure to be measured inlet provided in the second casing 8 is different. That is, a pressure introduction hole 12 is formed in the second casing 8, and holes 13 and 14 are inserted into the second casing 8 from both sides.
The members 15 and 16, which are opened with their centers shifted from each other, are inserted to create a space in the middle and are inserted so that the holes 13 and 14 do not overlap with each other to form a pressure to be measured inlet.

Furthermore, a taper 17 was provided on the measurement chamber side of this measured pressure inlet of the second casing 8.

According to the above configuration, when the pressure to be measured P1 is applied, the vaporized substance such as gasoline contained in the pressure medium to be measured is 1
When it enters the hole 14 of the member 16, it collides with the member 15 at one end, and then enters the pressure measurement chamber through the hole 13. During this time, it liquefies, making it difficult for it to enter the pressure measurement chamber, and further liquefying. This makes it easier to release it to the outside.

Furthermore, since the second casing 8 is provided with a taper 17 on the end face of the pressure to be measured inlet, liquefied substances do not accumulate in the pressure measurement chamber.

In addition, in the above-mentioned embodiment, the pressure introduction hole 12 is made in the casing 8 of 9JS2, and the holes 13 and 14 are inserted here, respectively.
I inserted the parts 15 and 16 that had been opened.

The parts 15, 16 can also be molded into the second casing 8.

FIG. 2 is a partial sectional view showing another embodiment of the joint portion 9 of FIG. 1. The joint 9 between the first casing 1 and the second casing 8 must not deteriorate due to thermal stress caused by the difference in thermal expansion between the adhesive and mold resin due to applied pressure and temperature changes in the pressure measurement chamber. . On the other hand, in the past, the joint strength was increased by providing a step at the joint part to increase the contact area with the adhesive. However, this is not enough, so in Figure 2 the first
A convex part 22 having relief grooves 21 at the upper and lower ends is provided in the center of the joint part of the casing 1 with the second casing 8, and the joint part of the second casing 8 with the first casing 1 is provided. A recess 23 into which the protrusion 22 fits is provided in the center, and the first casing 1 and the second casing 8 are joined together as shown in FIG. 2 by applying an adhesive 30 to the joint. I made it.

In this way, the durability of maintaining confidentiality can be improved.

In addition, as in the embodiment shown in FIG. 3 instead of FIG.
The joint part of the casing 1 is formed into an L-shape having an escape groove 24 at the bent part, and the joint part of the second casing 8 is formed into an L-shape that fits into the L-shaped joint part of the first casing 1. The same effect can be obtained by forming a letter-shaped structure and joining the joint portions of the two with adhesive 30.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to protect a semiconductor strain gauge from harmful liquefied substances and vaporized substances contained in the pressure medium to be measured, and furthermore, the escape groove can be filled with adhesive. This has the effect of increasing the adhesive force between the casings.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram showing one embodiment of the semiconductor pressure sensor of the present invention, FIG. 2 is a partial sectional view showing another embodiment of the joint portion of FIG. 1, and FIG. FIG. 4, a partial cross-sectional view showing another embodiment, is a structural diagram of a conventional semiconductor pressure sensor.

Claims (1)

[Claims] 1. A U-shaped silicon chip with a semiconductor strain gauge formed on its surface is fixed to a first casing via a semiconductor strain gauge support, and the first casing is fixed to a second casing. In the semiconductor type pressure sensor in which the second casing is provided with a pressure to be measured inlet, the structure of the to-be-measured pressure inlet is made by inserting a member in which holes are opened from both sides of the pressure inlet hole with the center shifted from each other. The second casing on the pressure measurement chamber side of the pressure to be measured inlet is tapered. A semiconductor pressure sensor characterized by the following. 2. The joint between the first casing and the second casing is composed of at least two orthogonal planes, and the orthogonal part has an escape groove for an adhesive, and the joint is bonded with the adhesive. Claim 1
Semiconductor pressure sensor described in section.