JPH0648370Y2 - Semiconductor pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a semiconductor pressure sensor, and more particularly to a semiconductor pressure sensor using a flexible printed wiring board for terminal processing of input / output signals.

[Conventional technology]

Pressure sensors are used in a wide range of applications such as measurement in various industries, process control, automatic control devices for medical equipment, hydraulic equipment, etc.

FIG. 4 is a cross-sectional view showing an example of a semiconductor pressure sensor that is particularly widely used among the pressure sensors that have been conventionally used.

In this figure, 1 is a cylindrical front case 1A and a terminal case
The case body is made of 1B and is made of iron or stainless steel.

Reference numeral 2 is a thin film diaphragm whose outer periphery is welded to the case body 1, 3 is a semiconductor chip in which a P-type strain gauge layer on four sides is formed on an N-type silicon substrate by a diffusion technique, and 4 is the semiconductor chip 3 mounted thereon. The glass base 4 is fixed to the inside of the front case 1A by a support plate 5.

Reference numeral 6 denotes a lead piece from which the pattern electrode of the semiconductor chip 3 is drawn out by the bonding wire 7, and the other end of the lead piece 6 is connected to a substrate 9 which is insulated and fixed to the case body 1 as described later.

Reference numeral 9 denotes a substrate fixed in the terminal case 1B, on which a constant current source circuit, an IC circuit forming a temperature compensation circuit, and other electronic component elements 10, 10 ... Are mounted. .

Reference numeral 11 denotes a multi-core cable or a flexible printed wiring board that serves as an input / output line of this semiconductor pressure sensor, one end of which is attached to the substrate 9 and is connected to the electronic component elements 10, 10 ... Alternatively, the output of the sensor is derived to the outside.

The inner space 8 of the diaphragm 2 is usually filled with silicone oil.

In such a semiconductor pressure sensor, for example, when the case body 1 is mounted on the wall surface of a liquid tank and the diaphragm 2 is brought into contact with the liquid, the diaphragm 2 is pressed by the pressure of the liquid, and the liquid of the silicon oil filled in the inside. The pressure rises. Therefore, the semiconductor chip 3 whose surface is in contact with the silicon oil is distorted by the pressure, and this distortion causes the P-type diffusion layers on the four sides to change in resistance due to the piezoresistive effect.

Therefore, the pressure applied from the outside of the diaphragm 2 can be measured by detecting this change in resistance as a change in voltage or current.

It should be noted that various electronic component elements 10 and 10 mounted on the substrate 9
Is provided close to the sensor in order to improve the temperature characteristics of the signal connected to the case 11 and to increase the S / N ratio.

[Problems to be solved by the invention]

Although such a semiconductor pressure sensor has high performance and high reliability in practical use, it has a problem in the manufacturing process.

That is, the work of fixing the board 9 on which the electronic circuit is mounted inside the case body 1 and connecting with the cable 11 is very difficult and poor in workability, so that there is a problem that the production efficiency is significantly reduced. there were.

Furthermore, the space in which elements can be mounted, that is, the plane area of the substrate 9 must, of course, be equal to or smaller than the area that can be accommodated in the case body 1, which is a disadvantage in that it is extremely limited in terms of circuit design. there were.

[Means for solving problems]

The present invention has been made in view of the above problems, and an input / output line of a semiconductor pressure sensor is configured by a flexible printed wiring board provided with an element mounting portion.

[Operation] An element mounting portion is formed on a flexible printed wiring board, and an electronic component is installed on this portion. By winding this element mounting portion and inserting it in the rear part of the case, the electronic mounting can be performed without using a substrate or the like. The parts can be housed and fixed in the case.

〔Example〕

1 (a) and 1 (b) are perspective views of a terminal portion of a semiconductor pressure sensor showing an embodiment of the present invention.
FIG. 1A is a perspective view after completion, and FIG. 1B is a development view before completion.

In the figure, 20 is a semiconductor pressure sensor body, and 21 is a thin film diaphragm.

22 is a fitting case made of iron, stainless steel, etc.,
A case front portion 22A having a semiconductor chip (not shown) and the like fixed therein and a case rear portion 22B for housing an element mounting portion as described later are integrated at the time of completion.

23 is a main flexible printed wiring board provided with a sub-flexible printed wiring board to be the element mounting portion 23A,
One end 23B is fixedly connected to the input / output terminals 24, 24 of the semiconductor chip in the front part 22A of the case by soldering or the like, and the other end is an input / output terminal 23C for an external circuit. . On the sub-flexible printed wiring board that will be the element mounting portion 23A, various electronic elements 25, 25 constituting a constant current source circuit, a temperature compensation circuit, an amplifier circuit, a chip resistor, etc.
Is mounted and fixed.

As described later, the semiconductor pressure sensor 20 using the main flexible printed wiring board 23, in which the elements 25, 25 ... Are mounted and fixed to a part thereof, is changed from the state shown in FIG. The semiconductor pressure sensor is completed by being housed in the state of a).

This point will be described below with reference to FIGS. 2 (a), (b) and (c).

First, the element mounting portion, on which the elements 25, 25 are mounted and fixed in advance, is wound into a small diameter (FIG. 2 (a)). Next, the rear portion 22B of the case is inserted through the main flexible printed wiring board 23 and the front portion of the case is inserted. The element mounting portion 23A, which is wound in a sufficiently small size, is inserted into the rear portion 22B of the case (FIG. 2 (b)). Then, after the case rear part 22B is inserted and fixed to the case front part 22A, a fixing material such as epoxy resin is injected into the case rear part 2B and cured, and the elements 25, 25, ... The printed wiring board 23 is fixed (FIG. 2 (c)).
At this stage, the terminal processing of the semiconductor pressure sensor 20 in the state shown in FIG. 1 (a) can be performed.

In the present invention, as described above, the element mounting portion 23A is provided in advance on the flexible printed circuit board in the direction orthogonal to the longitudinal direction thereof, and the elements 25, 25 ...
... is fixed by soldering, etc.
The work of arranging 25,25 ... inside the rear part 22B of the case is
This is much easier than conventional work and greatly improves work efficiency. In addition, elements 25, 25
Since the space where the ... Can be mounted can be made large on the main flexible printed wiring board 23, there is also an advantage that there is a margin in design space.

The flexible printed wiring board has a crank-shaped intermediate portion between the terminals connected to the semiconductor chip and the terminals connected to the external device, as shown in FIG. 1 or 3. However, by mounting an electronic component on this portion, it is possible to perform patterning so that a wasteful portion is reduced when a large number of substrates of the present invention are punched out from the flexible substrate.

[Effect of device]

As described above, in the pressure sensor of the present invention, the element mounting portion is provided on the flexible wiring board serving as the input / output terminal with the external circuit, and the electronic element can be mounted on the element mounting portion. The electronic element can be accommodated and fixed in the case only by winding the element mounting portion, inserting it into the case, and injecting the fixing material, which has the effect of significantly simplifying the manufacturing process.

In addition, compared with the case of using a normal substrate, the space where the device can be mounted is much wider, and there is an effect that a space in design is generated.

[Brief description of drawings]

1 (a) and 1 (b) are perspective views of an embodiment of the present invention, FIGS. 2 (a) to 2 (c) are explanatory views of a manufacturing process of an embodiment of the present invention, and FIG. 3 is a book. FIG. 4 is a plan view showing various shapes of a flexible printed circuit board in the semiconductor pressure sensor of the invention, and FIG. 4 is a sectional view showing a conventional example. In the figure, 20 is a semiconductor pressure sensor, 22A is a front part of the case, 22B is a rear part of the case, 23 is a main flexible printed wiring board, 23
A indicates an element mounting portion, and 25 indicates an electronic element.

Claims (1)

[Scope of utility model registration request] 1. A first terminal portion connected to a semiconductor chip and a second terminal portion connected to an external device are arranged in a vertical direction, and between the first terminal portion and the second terminal portion. A flexible board having a crank shape formed by a wiring pattern for connecting the wiring patterns in a horizontal direction and an electronic component mounted on the wiring pattern, and the flexible board formed in the crank shape has a horizontal direction. The semiconductor pressure sensor is characterized in that the above portion is rolled into a small-diameter tubular shape and is housed in the case of the semiconductor pressure sensor.