JPH04106440A - Pressure sensor - Google Patents

Abstract

PURPOSE:To efficiently and economically seal the integrated circuit part of a sensor by a resin by forming the pressure introducing port communicating with a cavity part to a substrate. CONSTITUTION:For example, an integrated circuit performing processing based on the detection output of a pressure-sensitive element is formed to the region slightly separated from the pressure-sensitive element 21 mounted on a ceramic substrate 20. Further, the pressure-sensitive element 21 is covered with a cover body 22 and a cavity part 23 is formed by the cover body 22 and a part of the substrate 20. The pressure introducing port 24 communicating with the cavity part 23 formed to the substrate 20 and the surfaces of the parts of the integrated circuit containing the cover body 22 are sealed by a resin to form a sensor. By this constitution, since the pressure-sensitive element 21 is provided in the cavity part 23 and the cavity part 23 is partitioned by the cover body 22, the inflow of the liquid resin to the cavity part is prevented by the cover body 22 when the surfaces of the parts of the integrated circuit of the substrate 20 are sealed by the resin. Therefore, the pressure-sensitive element 21 is not sealed by the resin and the surfaces of the parts of the substrate 20 can be sealed by the resin.

Description

[Detailed Description of the Invention] [Summary] Regarding a pressure sensor whose integrated circuit portion can be encapsulated with resin at low cost and efficiently, the integrated circuit portion of the pressure sensor formed in a hybrid IC type can be efficiently sealed. Another object of the present invention is to provide a pressure sensor that can be economically sealed with resin, and for this purpose, an integrated circuit is formed on a substrate, and a pressure sensitive element is electrically connected to at least a part of the integrated circuit. attached to the substrate, the pressure-sensitive element is covered with a coating, and a cavity is formed by the coating and a part of the substrate, while a pressure introduction port communicating with the cavity is formed in the substrate; Then, a component surface of the integrated circuit including the covering body is sealed with a resin to form a pressure sensor.

[Industrial application field]

The present invention relates to a pressure sensor whose integrated circuit portion can be sealed with resin at low cost and efficiently.

[Conventional technology]

Pressure sensors, for example, are sometimes provided with a single pressure-sensitive element configured as a semiconductor strain gauge, but in recent years, in consideration of user ease of use, they are not only provided with a single pressure-sensitive element. In most cases, a pressure-sensitive element and associated electronic circuits such as an amplifier circuit, an A/D conversion circuit, or a temperature compensation circuit are incorporated into a single substrate, in the form of a so-called hybrid IC. It has become to.

In such high-print ICs, hybrid ICs are generally housed in a package to prevent the semiconductors and metals from rusting, dust from adhering to them, and metal fatigue caused by vibration in the lead wires. A method has been adopted in which the gap between them is filled with resin to seal the integrated circuit section.

However, the pressure sensor formed in the above-mentioned hybrid IC has a pressure sensing element, and pressure needs to be transmitted to this pressure sensing element through a fluid (liquid or gas). It is not possible to seal the entire integrated circuit section with resin, including the pressure elements.

FIG. 2(a) is a schematic configuration diagram of a pressure sensor for explaining the resin sealing method in a conventional pressure sensor formed as a hybrid IC, and FIG.
) is a sectional view taken along line A-A in FIG. In FIG. 1A, a case 1 is formed with an integrated circuit portion 2 and a portion in which a pressure-sensitive element portion 3 is accommodated, separated by a partition wall 4. A necessary electronic circuit is formed on a ceramic substrate 6 (FIG. 6(b)) having a pull-out pin 5, and the case 1 is attached to the component surface of this ceramic substrate 6. Then, the integrated circuit section 2 is filled with liquid resin, and when this liquid resin solidifies, a resin filled section 7 is formed, and the product is completed.

On the other hand, a pressure introduction port 9 is formed in a portion of the case 1 facing the pressure-sensitive element 8 provided in the pressure-sensitive element section 3, and the outside of the case 1 and the inside of the pressure-sensitive element section 3 are connected to each other. The pressure is maintained at the same level as the air pressure, and the structure is configured so that the atmospheric pressure can be detected.

FIG. 3(a) is a schematic configuration diagram of a pressure sensor for explaining another method of resin sealing in a conventional pressure sensor formed as a hybrid IC, and FIG. It is a BB sectional view in .

In the figure (a), a necessary electronic circuit is formed on a ceramic substrate 10 (the figure (b)) having a pull-out pin 5, and a pressure sensitive element 8 is provided in a part thereof. Further, this pressure sensitive element 8 is surrounded by a rubber ring 11, and the inside of this rubber ring 11 serves as a pressure sensitive element section 12. The case 13 is a housing having an opening on one side, and the ceramic substrate 10 is inserted through this opening, and the remaining portion other than the portion surrounded by the rubber ring 11 is filled with liquid resin. Then, when this liquid resin solidifies, a resin filling portion 14 is formed and a product is completed. Further, a pressure inlet 9 is formed in a portion of the case 13 facing the pressure sensitive element 8, and the outside of the case 13 and the inside of the pressure sensitive element section 12 are kept at the same pressure, and the pressure is maintained at the same pressure. It is configured so that it can be detected.

[Problem to be solved by the invention]

In the resin sealing method described above, when filling a portion other than the pressure-sensitive element portion with liquid resin, it is necessary to gradually inject the liquid resin so that the liquid resin is spread to every corner. Therefore, there were problems in that the work was troublesome, required a lot of time, and was not efficient.

By the way, in addition to the above-described method of forming a resin-filled portion (mold portion), a method called a transfer molding method is known as a resin sealing method that can be performed more quickly. This is a molding method in which a member to be molded is placed in a mold of a fixed shape, filled with liquid resin, and when the liquid resin has solidified, the member to be molded is removed from the mold.

However, in the case of the conventional pressure sensors shown in FIGS. 2 and 3, it is necessary to form the pressure-sensitive element portion and the pressure introduction port, so resin sealing is performed using the transfer molding method described above. The problem was that it was impossible.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, an object of the present invention is to provide a pressure sensor in which the integrated circuit portion of a pressure sensor formed in a hybrid IC type can be efficiently and economically sealed with resin. shall be.

[Means for solving the problem] A pressure-sensitive element is mounted on a substrate, for example, a ceramic substrate, and a portion of the ceramic substrate slightly distant from the pressure-sensitive element is processed based on the detection output of the pressure-sensitive element. form integrated circuits; Further, the pressure sensitive element is covered with a covering, and a cavity is formed by the covering and a part of the substrate.

On the other hand, a pressure inlet communicating with the cavity is formed in the substrate, and a component surface of the integrated circuit including the cover is sealed with resin to form a pressure sensor.

[For production]

In the pressure sensor configured as described above, the pressure sensing element is located in the cavity, and this cavity is partitioned by the covering, so that the component surface of the integrated circuit on the substrate is sealed with resin. When stopping, the covering prevents the liquid resin from flowing into the cavity. Therefore, the pressure-sensitive element is not sealed with resin, and the component surface of the substrate can be sealed with resin using a transfer molding method.

On the other hand, since the pressure introduction port opens on the non-component surface side of the substrate in the vicinity of the pressure sensitive element, external pressure is transmitted to the pressure sensitive element through this pressure introduction port without any problem.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1(a) is a schematic rear view showing a pressure sensor according to the present invention, and FIG. 1(b) is a sectional view taken along the line XX in FIG. 1(a). Referring to both figures, a pressure sensitive element 21 is mounted on a substrate, for example, a ceramic substrate 20, and a portion of the ceramic substrate 20 slightly away from the pressure sensitive element 21 is provided with a detection output of the pressure sensitive element. Mounting components that constitute an integrated circuit that performs processing based on the information are provided. The pressure-sensitive element 21 is, for example, a bridge circuit using a semiconductor strain gauge, and the integrated circuit includes an electronic circuit such as an amplifier circuit, an A/D conversion circuit, or a temperature compensation circuit, and the detection output of the pressure-sensitive element 21 is The signal is input to the amplifier circuit.

The pressure sensitive element 21 is covered with a cover 22 made of plastic, rubber, metal, or other material, and a cavity 23 is formed by the cover 22 and a part of the substrate 20. Note that the covering body 22 is attached to the ceramic substrate 2.
0, apply adhesive to the peripheral edge of the covering 22.
For example, it is attached to the ceramic substrate 20 using instant adhesive.

On the other hand, a pressure introduction port 24 communicating with the cavity 23 is formed in a portion of the substrate 20 near the pressure-sensitive element 21, and a component surface of the integrated circuit including the cover 22 is sealed with resin. .

For this resin sealing, with the covering body 22 fixed to the ceramic substrate 20, the part surface is turned upward, and a dish-shaped mold is placed over it.

Then, an injection nozzle for injecting liquid resin is made to face a small hole drilled in the upper surface of the mold, and the inside of the mold is filled with the liquid resin. The ceramic substrate 20 is left filled with liquid resin for a predetermined period of time, and when the liquid resin solidifies, the ceramic substrate 20 is removed from the mold. Resin sealing can be performed by a so-called transfer molding method. As a result, a resin filling portion 25 is formed on the component surface of the ceramic substrate 20.

〔Effect of the invention〕

As described above in detail, according to the present invention, it is possible to transfer mold an integrated circuit part, etc. with the pressure sensitive element covered with a cover, and the time required to complete the product can be reduced. Moreover, since a case with a special structure is not required, resin sealing can be performed economically. Since the pressure inlet is opened on the non-component side of the substrate in the vicinity of the pressure sensitive element, the product is completed as soon as the resin sealing is completed, making it possible to provide pressure sensors with excellent performance at a low price. become.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic back view showing a pressure sensor according to the present invention, FIG. 1(a) is a cross-sectional view taken along the line X-X in FIG. 1(a), and FIG. A schematic configuration diagram of a pressure sensor for explaining the resin sealing method in a conventional pressure sensor, FIG. 2(b) is a sectional view taken along the line A-A in FIG.
FIG. 3(a) is a schematic configuration diagram of a pressure sensor for explaining another method of resin sealing in a conventional pressure sensor formed as a hybrid IC, and FIG.
There is B in a). 20...Ceramic substrate, 21...Pressure sensitive element, 22...Coating, 23...Cavity part, 24...Pressure introduction port, 25...Resin filling part 6 In the B-line sectional view

Claims (1)

[Claims] An integrated circuit is formed on a substrate, a pressure sensitive element electrically connected to at least a part of the integrated circuit is mounted on the substrate, the pressure sensitive element is covered with a covering body, and the covering body and the substrate are combined. A hollow portion is formed by a portion of the integrated circuit, and a pressure introduction port communicating with the hollow portion is formed in the substrate, and a component surface of the integrated circuit including the covering body is sealed with a resin. pressure sensor.