JPH0727787A - Semiconductor-type acceleration sensor - Google Patents

Abstract

PURPOSE:To prevent the operating defect of a cantilever due to dust particles or the like and to enhance the production yield and the quality of an accelaration sensor by a method wherein a semiconductor-type sensor element is covered with a sensor cover. CONSTITUTION:A plate spring part 7 and a mass part 8 are installed on a beam part 5, and the semiconductor-type acceleration sensor element is formed. The sensor element and a peripheral circuit 9 are mounted on a substrate 4, and the substrate 4 is attached to a base 1. A metal shell 13 which covers the whole of the substrate 4 is welded to the base 1 at its peripheral edge part. Then, a sensor cover 20 is formed to be a box shape, its lower-side face is opened, and the whole of the sensor element is covered from the upper part. In addition, the sensor cover 20 is bonded to the substrate 4, and a plurality of gas ventilation holes 21 are made on the upper-side face of the sensor cover 20 so as to provide a function by which an inert gas, for oxidation prevention, which is sealed in the metal shell 13, flows into the sensor cover 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor type acceleration sensor.

[0002]

2. Description of the Related Art The structure of a conventional semiconductor type acceleration sensor will be described with reference to FIG. In the figure, reference numeral 1 is a flat metal stem (base), and a through hole for electrical connection with the outside is formed in the peripheral portion thereof, and the hard glass 2 is welded to the through hole. The lead terminal 3 is fixed by. The lead terminal 3 and the stem 1 are electrically insulated by a hard glass 2, and the hard glass 2 is interposed with good airtightness. A ceramic substrate 4 is mounted on the stem 1, and the ceramic substrate 4
A semiconductor type acceleration sensor element including a cantilever (beam portion) 5 and a pedestal 6 is mounted on the top.

The cantilever 5 has a thin plate spring portion 7 formed at the base by etching a semiconductor plate, and one end thereof is fixed to the pedestal 6. Further, the thick-walled portion formed at the tip portion of the cantilever 5 is formed so as to have a free end 8 capable of displacing a part (mass) thereof according to the acceleration to be measured. Further, a strain gauge is formed in the leaf spring portion 7 and is electrically connected to a circuit 9 formed on the ceramic substrate 4 by wire bonding, and the wire 9 is connected from the circuit 9 to the lead terminal 3.
Are electrically connected by wire bonding. 12
Is a stopper, the shape of which is an inverted L-shape and is erected so as to regulate the maximum amount of upward displacement of the cantilever 5.

Reference numeral 13 designates a metallic shell having a flange 14 formed on the peripheral edge thereof, which has a recess formed by press working to form a box shape, and the peripheral edge is welded to the peripheral edge of the stem 1 in an inert gas. It is hermetically sealed. The hermetic sealing is performed by covering the stem 1 with the metallic shell 13 from above so that the peripheral edge of the stem 1 is aligned with the flange portion 14 of the metallic shell 13 and bringing them into contact with each other, while applying pressure by a press. The electric shell 13 and the stem 1 are energized to weld them together.

When acceleration is applied to the semiconductor type acceleration sensor in the vertical direction from the outside, the free end 8 of the cantilever 5 vibrates in the vertical direction, and as a result, the leaf spring portion 7 is distorted. Cause The resistance value of the semiconductor strain gauge changes according to the magnitude of the strain, and the acceleration is detected as an electric signal.

[0006]

However, in the welding of the plate-like stem 1 and the metallic shell 13 as described above, as shown in FIG. High heat is generated due to welding while energizing while pressing, and fine molten metal splash powder is sprayed toward the inside of the metal shell 13 as fine particles 1
5 scatters, enters a minute gap between the cantilever 5 and, for example, the pedestal 6, and causes a vertical vibrational disturbance of the cantilever 5, resulting in a malfunction.

In addition, there is a possibility that dust and dust floating in the surrounding environment for producing the semiconductor type acceleration sensor of the present invention may enter into a minute gap between the cantilever 5 and the pedestal 6 as described above. It is an object of the present invention to prevent malfunction of the cantilever 5 due to dust, dust, etc., and improve the production yield and quality of the semiconductor acceleration sensor.

[0008]

SUMMARY OF THE INVENTION A semiconductor type acceleration sensor according to the present invention includes a semiconductor type acceleration sensor element having a beam portion and a mass provided on the beam portion, the semiconductor type acceleration element and its periphery. Circuit is installed,
In a semiconductor type acceleration sensor comprising a substrate mounted on a base and a metallic shell covering the entire substrate from above the substrate and having a peripheral edge welded to the substrate, the semiconductor type acceleration sensor element is provided by a sensor cover. Be covered.

[0009]

According to the above structure, the semiconductor type acceleration sensor element is covered with the sensor cover to prevent dust and dirt from entering during the manufacturing process and prevent malfunction of the cantilever.

[0010]

Embodiments of the present invention will be described in detail with reference to FIGS. 1 and 2. 1 and 2, the same or equivalent components as those described with reference to FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted. Figure 1
In addition, in FIG. 2, reference numeral 20 denotes a sensor cover, which is formed in a box shape and has a lower side surface opened so as to cover the entire semiconductor type sensor element from above. Further, the sensor cover 20 is adhered to the ceramic substrate 4, and a plurality of gas flow holes 21 are formed on the upper side surface of the sensor cover 20 so that the inert gas for oxidation sealed in the metallic shell 13 is used as the sensor. It has a function of flowing into the cover 20.

[0011]

As described above, according to the present invention, the malfunction of the cantilever can be prevented, so that the quality of the sensor can be improved and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view for explaining an embodiment according to the present invention.

FIG. 2 is a cross-sectional explanatory diagram of FIG.

FIG. 3 is a cross-sectional explanatory view of a conventional example.

FIG. 4 is an explanatory diagram of a defect of a conventional example.

[Explanation of symbols]

 20 sensor cover 21 gas flow hole

Claims (1)

[Claims] 1. A semiconductor type acceleration sensor element having a beam portion (5), and a plate spring portion (7) and a mass portion (8) provided on the beam portion, and the semiconductor type acceleration element and its surroundings. A circuit board (9) is mounted and is mounted on the base (1), and a metallic shell (13) is formed by welding the circuit board (4) from above and covering the entire circuit board (4) at its peripheral edge. And a semiconductor type acceleration sensor, wherein the semiconductor type acceleration sensor element is covered with a sensor cover (20).