JPH095197A - Semiconductor pressure sensor - Google Patents

Abstract

PURPOSE: To reduce noise due to external influence such as temperature change and make it possible to use a semiconductor pressure sensor also for an organic solvent gas. CONSTITUTION: A sensor element 20 of a semiconductor and a pressure introducing cylinder 25 for introducing a pressure to be measured are joined airtightly. A plurality of spacers 30 including a spherical silicon, ceramic, or silica powder in nearly equal diameter are pinched in one layer between the sensor element 20 and the pressure introducing cylinder 25, and fluoro-silicone resin 32 is filled in the gap for connection.

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 which receives a fluid pressure by a semiconductor diaphragm, converts the pressure into an electric signal and outputs the electric signal.

[0002]

2. Description of the Related Art Conventionally, a semiconductor type pressure sensor has been provided as a small pressure sensor capable of accurately measuring the pressure of a fluid. Here, a semiconductor pressure sensor that eliminates noise caused by a difference in coefficient of thermal expansion between a sensor element and a base to which the sensor element is attached is disclosed in JP-A-59-102131. In this semiconductor pressure sensor, a gel silicon resin is interposed between the sensor element and the base to make it difficult for force to be transmitted between the sensor element and the base, and to allow thermal expansion between the sensor element and the base. By absorbing the difference in expansion and contraction caused by the difference in the coefficient, the noise due to the temperature change is eliminated.

[0003]

When the conventional semiconductor pressure sensor is used to measure the pressure of an organic solvent gas such as methane gas, propane gas, gasoline, etc., the organic solvent gas permeates into the gel-like silicone resin, and FIG. From the state shown in FIG. 6, as shown in FIG. 6, the adhesive layer 28 of the silicone resin swells gradually and the diaphragm of the sensor element 20 is distorted, which causes noise in the output signal. And
When the swelling spreads throughout the adhesive layer 28, the strain of the sensor element 20 disappears, as shown in FIG. Therefore, the silicone resin adhesive is not suitable for the measurement of organic solvent gas and the like. Therefore, as the die bonding material between the sensor element of the semiconductor pressure sensor that can be used for the organic solvent gas and the base, an inorganic bonding member such as a metal wax or an organic bonding member such as a solvent resistant synthetic rubber is used. Was limited to. However, these bonding materials also do not always match the required bonding conditions of the semiconductor pressure sensor element, and sacrifice the sensor element characteristics such as accuracy, linearity, and temperature characteristics.

The present invention has been made in view of the above problems of the prior art, and is a semiconductor pressure sensor which has less noise due to external influences such as temperature change and can be used for organic solvent gas. The purpose is to provide.

[0005]

According to the present invention, a semiconductor sensor element and a pressure introducing tube for introducing a pressure to be measured are joined in an airtight state, and the sensor element and the pressure introducing tube. A semiconductor pressure sensor in which a fluorosilicone resin is filled and connected between the two. Moreover, in the meantime,
This is a semiconductor pressure sensor in which a plurality of spacers made of spherical silicon, ceramics, or silica powder having substantially the same diameter are sandwiched in a single layer, and the gap is filled with a fluorosilicone resin and connected.

[0006]

According to the pressure sensor of the present invention, the organic solvent gas, which is the pressure medium to be measured, passes through the pressure introducing tube and directly enters the back surface side of the semiconductor pressure sensor element. At this time, the pressure sensor element and the pressure introducing tube are joined. Although the organic solvent gas comes into contact with the layer, the fluorosilicone resin, which is the die-bonding material of the bonding layer, is less swelled by the organic solvent and does not give strain to the pressure sensor. Furthermore, since the spherical spacer forms an extremely thin die bonding material layer between the pressure sensor element and the pressure introducing cylinder, the vertical deformation of the bonding layer can be suppressed to an extremely small value. Thereby, the strain applied to the sensor element due to the temperature change is suppressed to a minimum.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the pressure sensor of this embodiment, as shown in FIG. 1, the Si semiconductor sensor element 20 has a sensor case 2
1, the sensor element 20 and the base end 22a of the lead frame terminal 22 are wire-bonded with a gold wire 23. In the sensor case 21, a lead frame terminal 22 and a pressure introducing tube 25, which is a pressure introducing portion, are integrally provided by insert molding. The pressure introducing tube 25 has a flange portion 26 for mounting a sensor at a base end portion. Are formed. The sensor element 20 is adhered to the flange portion 26 in an airtight state by the joining layer 28.

As shown in FIG. 4, the lead frame terminals 22 are soldered to the board 40 and electrically connected to the external connection terminals 42 attached to the board 40.
Here, in FIG. 4, the right side of the center line is a vertical section in the extension direction of the lead frame terminal 22, and the left side of the center line is a vertical section in a direction orthogonal to the extension direction of the lead frame terminal 22. Sensor case 21 to which the substrate 40 is fixed
Is attached to the outer case body 41, and the pressure introducing tube 2
An O-ring 46 made of, for example, an organic solvent resistant rubber is tightly fitted between 5 and the inner wall surface of the outer case body 41. A lid member 48 is attached to the outer case body 41, and an atmospheric pressure inlet port 49 connected to the atmospheric pressure side is formed in the lid member 48.

In this embodiment, as shown in FIGS.
In the bonding layer 28 between the sensor element 20 and the flange portion 26, a plurality of spherical spacers 30 for setting a constant distance between the sensor element 20 and the flange portion 26 are arranged in a layer, and the spacers are arranged in a single layer. The fluorosilicone resin 32 is filled so as to wrap it, and the sensor element 20 and the flange portion 26 are bonded to each other. This fluorosilicone resin 32 is obtained by substituting all or part of the methyl group of the side chain of dimethyl silicone rubber with a fluorine compound such as trifluoropropylmethyl, and this resin has all the characteristics of ordinary silicone resin. In addition, the solvent resistance is remarkably improved.

However, as shown in FIGS. 5 to 7, the fluorosilicone resin also causes a slight swelling when it comes into contact with the organic solvent gas, and the signal drifts until the organic solvent gas permeates and diffuses. To continue. As a countermeasure, a spherical spacer 30 is sandwiched in a layer of fluorosilicone resin 32 between the sensor element 20 and the flange portion 26, and the spacer 30 is extremely thin between the sensor element 20 and the flange portion 26. A fluorosilicone resin layer is formed and fixed. Therefore, even if the fluorosilicone resin 32 comes into contact with the organic solvent gas and swells,
This ultra-thin layer minimizes distortion by not causing vertical changes to the noise of the signal. Therefore, the drift of the signal can be considerably suppressed. The suppression amount is the filling rate of the spacer, the sensor element 20.
Is determined by the rigidity of.

In the method of using the pressure sensor of this embodiment, first, the pressure introducing portion 45 is connected to the measured pressure side, and the atmospheric pressure introducing port 49 is opened to the atmospheric pressure side. The organic solvent gas or the like whose pressure is to be measured passes through the pressure introducing portion 45, passes through the pressure introducing cylinder 25, and directly contacts the back surface side of the sensor element 20, and the sensor element 20 is distorted by pressure and changes accordingly. The resistance value of the element 20 is detected, and the pressure of the organic solvent gas or the like is measured.

Since the fluorosilicone resin used in the pressure sensor of this embodiment has the characteristics of ordinary silicone resin, the electrical characteristics of the sensor element 20 are not impaired, and the sensor element 20 changes due to temperature changes. And flange 26
It is possible to absorb the difference in expansion and contraction that occurs between and.
This pressure sensor has a spherical spacer 3 on the bonding layer 28.
By sandwiching 0, the strain caused by the swelling of the fluorosilicone resin by the organic solvent can be suppressed to a minimum, and the bonding layer 28 having a uniform thickness can be formed without sacrificing workability. It is possible and has excellent reproducibility.

[0013]

According to the pressure sensor of the present invention, even when the fluid to be measured is an organic solvent gas, the noise of the sensor due to the permeation of the organic solvent gas into the fluorosilicone resin is extremely small,
The electrical characteristics such as accuracy, linearity, and temperature characteristics of the sensor element are extremely good. Furthermore, with the spacer,
Even if the fluorosilicone resin swells, the strain due to the swelling does not affect the sensor element and the accuracy of the measured value is high.

[Brief description of drawings]

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

FIG. 2 is an enlarged vertical sectional view of a joint layer between a sensor element and a flange portion of the pressure sensor of this embodiment.

FIG. 3 is an enlarged view of a joint portion between a spacer and a flange portion in FIG.

FIG. 4 is a vertical cross-sectional view showing a state in which the pressure sensor of this embodiment is attached to an outer case.

FIG. 5 is a schematic diagram showing the behavior of a silicone resin in an organic solvent gas environment.

FIG. 6 is a schematic diagram showing the behavior of a silicone resin under an organic solvent gas environment.

FIG. 7 is a schematic diagram showing the behavior of a silicone resin under an organic solvent gas environment.

[Explanation of symbols]

 20 Sensor element 25 Pressure introducing cylinder 28 Bonding layer 30 Spacer 32 Fluorosilicone resin

Claims (3)

[Claims] 1. A semiconductor pressure sensor in which a semiconductor pressure sensor element and a pressure introducing portion for introducing a measured pressure are joined in an airtight state, and a fluorosilicone resin is filled between the pressure sensor element and the pressure introducing portion. A semiconductor pressure sensor characterized in that it is adhered and bonded. 2. A semiconductor pressure sensor in which a semiconductor pressure sensor element and a pressure introducing portion for introducing a measured pressure are joined in an airtight state, and a plurality of spherical spacers are provided between the pressure sensor element and the pressure introducing portion. It is sandwiched between individual layers,
A semiconductor pressure sensor characterized in that a gap between the pressure sensor element, the pressure introducing portion cylinder and the spacer is filled with and bonded with a fluorosilicone resin. 3. The semiconductor pressure sensor according to claim 2, wherein the spacer is made of silicon, ceramics, or silica.