JPH04262217A - Hydraulic sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To solve the problem of the high cost for fixing a metal diaphragm in a structure wherein pressure to be measured is applied on a pressure transmitting medium in contact with a semiconductor diaphragm having a gage resistor. CONSTITUTION:The second gel material is brought into contact with the first gel material which is in contact with the surface of a semiconductor diaphragm having a gage resistor. Pressure to be measured is applied to the semiconductor diaphragm through two gel layers. Thus, a metal diaphragm is omitted. The first gel layer is mechanically protected by using a material whose penetration value is small for the second gel material or impregnating a metal mesh with the second gel material.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to toilets, showers,
The present invention relates to a water pressure sensor used for detecting water pressure in baths, etc., and a method for manufacturing the same.

0002

[Prior Art] A water pressure sensor using a semiconductor does not directly contact a fluid having a pressure to be measured with a semiconductor diaphragm equipped with a gauge resistor, but instead transfers the pressure to be measured to one side of the diaphragm through a fluid sealed in a container. What is added is known. Figure 2 shows the structure of the water contact part of a conventional water pressure sensor.
A thin diaphragm 2 made of stainless steel with excellent corrosion resistance is provided to prevent direct contact of fluid with the diaphragm of the pressure-sensitive semiconductor chip 1 and to protect the chip from impulsive pressure waves, and a spacer is provided to support it. 3 is used, and the diaphragm 2, spacer 3, container stem 4, and cap 5 are connected to each other by welding or silver soldering. A semiconductor chip 1 is supported by a stem 4 via a pedestal 6, and a gauge resistance output signal processing circuit on the semiconductor chip 1 and a lead wire 7 are connected by a conductive wire 8. Then, diaphragm 2, spacer 3 and stem 4
For example, silicone oil is injected as the pressure transmission medium 9 into the space surrounded by the inlet 10 from the inlet 10, and the inlet is sealed off.

0003

[Problems to be Solved by the Invention] Since this type of pressure sensor is used at home, it is only 1/2 the size of a sensor for an automobile, for example.
A low price is required. However, it is difficult to weld or silver braze to fix the diaphragm, and it is difficult to control air intrusion when sealing the pressure transmission medium.
Since sealing also takes time, costs increase, and the above requirements cannot be met.

[0004] An object of the present invention is to provide a durable and inexpensive water pressure sensor that does not have a diaphragm for pressure transmission, yet ensures sensor accuracy, and a method for manufacturing the same.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the water pressure sensor of the present invention includes a layer made of a first gel material on the surface of a diaphragm of a semiconductor element having a diaphragm portion provided with a gauge resistance. are in contact with each other, and a layer made of a second gel material having a smaller penetration value than the first gel material after hardening is in contact with the side of the gel layer farther from the semiconductor element. Alternatively, a layer made of a second gel material impregnated into a metal mesh is in contact with the layer made of the first gel material on the side farther from the semiconductor element.

The method for manufacturing a water pressure sensor of the present invention includes fixing a semiconductor body having a diaphragm portion provided with a gauge resistor on the bottom of a container with the diaphragm surface facing upward, and covering the semiconductor body in the internal space of the bottom of the container. A first gel material is filled with the first gel material, and then cured, and a second gel material whose penetration value after curing is smaller than that of the first gel material is filled into the inner space of the upper lid of the basin-shaped container having an opening on the top surface. The container bottom and top lid are then joined together to bring the first and second gel materials into contact. Alternatively, a semiconductor body having a diaphragm portion provided with a gauge resistance is fixed on the bottom of a container with the diaphragm surface facing upward, and the first gel material is filled in the space inside the bottom of the container to cover the semiconductor body. After curing, a metal mesh is separately laminated in the space inside the top lid of a basin-shaped container having an opening on the top surface, and then the metal mesh is impregnated with a second gel material and hardened, and then the bottom of the container and the top lid are joined. The first and second gel materials shall be brought into contact.

[0007]

[Operation] A layer made of the first gel material and a layer made of the second gel material are laminated on the diaphragm portion of the semiconductor element having a gauge resistance, so that the layer comes into contact with the surface of the second gel material. Fluid pressure is applied to the diaphragm of the semiconductor element through the two gel materials. By having the second gel material have a smaller penetration value than the first gel material, or by impregnating the metal mesh with the second gel material, the gel material can be maintained even when the measured pressure of the fluid becomes negative. The layer does not stretch and tear, and has a higher waterproofing function than gel materials with higher penetration values. Alternatively, a layer made of a first gel material and a layer of metal mesh impregnated with a second gel material are laminated on the diaphragm part, so that the pressure of the fluid in contact with the surface of the second gel material is reduced by two gels. It is added to the diaphragm part through the material. In this case, even if the second gel material has the same penetration value as the first gel material, the metal mesh prevents the gel material from being sucked out when the measured pressure becomes negative. death,
Conversely, since the second gel material is also soft, it exerts a buffering effect against impactful pressure waves, improving water resistance and durability. In either case, a diaphragm in the pressure transmission section is not required.

In order to assemble a water pressure sensor having such a structure, a container is composed of a trough-shaped bottom and a trough-shaped top lid having an opening at the top, and a semiconductor element and a first gel material are placed in the bottom. After storing the second gel material in the upper lid, the bottom part and the upper lid are combined so that the first gel material and the second gel material are in contact with each other. It is applied to the diaphragm of the semiconductor element through the opening through two gel materials. In this case, all you need to do is inject or impregnate the gel material into the open bottom of the container or the top lid.
Air entrainment can be easily controlled, and troublesome steps such as pouring gel material into a sealed container and sealing the container can be omitted.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to figures in which parts common to those in FIG. 2 are denoted by the same reference numerals.

In the embodiment shown in FIG. 1, a pressure-sensitive diaphragm chip 1 equipped with a thin film resistor on its surface and an operational amplifier for amplifying the output from a gauge resistor formed in the diaphragm part is attached to a metal basin-shaped container stem 4. An output signal processing circuit including a thin film resistor and an operational amplifier is fixed to the top with an adhesive via a pedestal 6, and a lead wire 7 is connected by an aluminum conducting wire 8. In this state, the thin film resistor on the chip is trimmed with laser light. Next, silicone gel 9 is injected up to the upper surface 11 of the stem 4 and cured. The hardness of the gel 9 is preferably soft enough so as not to affect the pressure sensitive characteristics of the chip 1. For example, using a penetrometer specified for JISK2235 petroleum wax, a mass of 2.5
A gel having a penetration value of 100 to 130, which is the penetration depth of a needle of ±0.05 g without adding a weight into the cured gel, is expressed in units of 0.1 mm. In a separate step, another gel 91 is injected up to the upper surface of the basin-shaped container cap 5 having the opening 51 on the top surface and hardened. This gel 91 is harder than the gel 9, and for example, a gel having a penetration degree of 70 to 90 as measured by the above method is used. After both gels 9 and 91 have been cured, the stem 4 and cap 5 are welded together.

In the embodiment shown in FIG. 3, a metal mesh 12 is laminated inside a container top 5 with an open top, although some parts are not shown in the figure, and is impregnated with gel 92. The metal mesh is made of stainless steel with corrosion resistance in mind, and is woven with fine wires with a wire diameter of 30 to 80 μm.The lamination method or lamination thickness is determined by stacking the mesh so that the weaves are in the same direction or randomly. Although determined by responsiveness, durability, and water resistance, it is appropriate to have 15 to 30 layers when laminated in the same direction, and about 10 to 20 layers when laminated randomly. The gel material 92 is brought into contact with such a metal mesh, impregnated with the gel material 92 by a vacuum defoaming method, and cured. The impregnated gel material 92 at this time has a hardness comparable to that of the gel material 9 injected into the stem 4, that is, a penetration degree of 100 to 130.
This gel material is used to provide a buffering effect against impactful pressure waves.

0012

[Effects of the Invention] In the present invention, a first gel material layer and a second gel material layer are laminated on a pressure-sensitive diaphragm semiconductor element, and the pressure of the fluid is applied through the two gel material layers. By applying it to the pressure-sensitive diaphragm, a diaphragm structure for pressure transmission is not required, and the cost of assembly is reduced. In addition, it becomes easier to fill the gel material and control the mixing of air into the gel material at that time. Then, by using a second gel material with a smaller penetration than the first gel material, that is, a hard material, or by impregnating a metal mesh with the second gel material, the second gel material can be penetrated into the first gel material layer. It is possible to manufacture an inexpensive water pressure sensor that has good waterproofness and durability, and has the same sensor accuracy as conventional ones.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a water pressure sensor according to an embodiment of the present invention.

[Figure 2
] Cross-sectional view of a conventional water pressure sensor

FIG. 3 is a sectional view of a water pressure sensor according to a different embodiment of the present invention.

[Explanation of symbols]

1 Pressure sensitive diaphragm chip 4 Container stem 5 Container cap 6 Pedestal 9 Gel 91 Gel inside the cap 92 Gel for impregnation 12 Metal mesh

Claims (4)

[Claims] 1. A layer made of a first gel material is in contact with the surface of a diaphragm of a semiconductor body having a diaphragm portion provided with a gauge resistance, and a layer of the first gel material is in contact with the surface of the diaphragm of a semiconductor body having a diaphragm portion provided with a gauge resistance, and a layer of the first gel material is placed on the side of the gel layer remote from the semiconductor body after hardening. A water pressure sensor characterized in that a layer made of a second gel material having a penetration value smaller than that of the material contacts the water pressure sensor. Claim 2: A layer made of a first gel material is in contact with the surface of a diaphragm of a semiconductor body having a diaphragm portion provided with a gauge resistance, and a metal mesh is impregnated on the side of the gel layer remote from the semiconductor body. A water pressure sensor characterized by being in contact with a layer made of a second gel material. 3. A semiconductor element having a diaphragm portion provided with a gauge resistor is fixed on the bottom of a basin-shaped container with the diaphragm surface facing upward, and a first gel material is applied to the inner space of the container bottom to cover the semiconductor element. After filling and hardening, a second gel material having a smaller penetration value after hardening than the first gel material is filled into the inner space of the upper lid of a basin-shaped container having an opening on the top surface, and then the bottom of the container and A method of manufacturing a water pressure sensor, comprising: combining a top cover and bringing first and second gel materials into contact with each other. 4. A semiconductor body having a diaphragm portion provided with a gauge resistor is fixed on the bottom of a basin-shaped container with the diaphragm surface facing upward, and a first gel material is applied to cover the semiconductor body in the space inside the bottom of the container. After filling and curing, a metal mesh is laminated in the space inside the upper lid of a basin-shaped container having an opening on the top surface, and the metal mesh is impregnated with the second gel material and hardened, and then the bottom of the container and the upper lid are laminated. A method for manufacturing a water pressure sensor, comprising combining first and second gel materials into contact with each other.