JPS6079242A - Pressure converter - Google Patents

Abstract

PURPOSE:To obtain a small absolute pressure reference type pressure converter not limited by gas to be measured and good in detection accuracy, by a method wherein a piezoelectric resistor forming surface is directed to a vacuum chamber side while a detection circuit is provided in a vacuum case and a detection circuit is further formed to the enamel part of the case by thick film printing. CONSTITUTION:The enamel part 2 of a metal base 1 is subjected to plating treatment and further receives glass coating while a thick film circuit 6 is formed onto the enamel part by printing. A pressure introducing pipe 8 is hermetically sealed to the central hole of the base 1 with glass 10 while an input output lead pin 7 and an evacuating pipe 9 are hermetically sealed to the other hole thereof with said glass 10. In addition, a glass die 11 and a silicon diaphragm 5 are bonded onto the pipe 8. A piezoelectric resistor is formed to the opposite side of the recessed part of the diaphragm 5 and, after the connection of the circuit, a metal cap 14 is provided to the glass coat removed part of a base board 4 by resistance welding and, after evacuation, the pipe is sealed to form a vacuum chamber 15. By this method, a silicon chip, a compensation circuit and an amplifier circuit are sealed under vacuum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pressure transducer, and more particularly to an absolute pressure reference type pressure transducer.

[Background of the invention]

As an example of a conventional absolute pressure reference type output converter, for example,
It is known that it was disclosed in Japanese Patent Application Laid-Open No. 56-29135. In this known method, one side of a silicon chip is processed by etching to make it thin, and a piezoresistor is formed on the opposite side by diffusion. Then, the four parts of this silicon chip were glued to the base, and the four parts and the second vacuum festival were made. The pressure for measurement is the formation surface f of the piezoresistor.
llll will be introduced. This base is housed in a resin housing together with a thick film circuit board that amplifies the output signal from this gauge and performs temperature compensation.

The problem with this conventional example is that pressure is introduced to the anti-forming surface side. Then,
Piezo resistance changes. Therefore, the gas to be measured is limited.

On the other hand, suppose that the gas to be measured is introduced into the four sides of the silicon chip, for example '', JP-A-57-1
86137, 57 186] 38 copies etc.
I'm being attacked. This thing is a-9 and 1. The piezoresistance forming surface side faces the inner surface of the metal case, and the inside of the case is used as a vacuum chamber. Furthermore, within this case, increase Ill'? It has a built-in thick film circuit board for lra degree compensation, making the whole device smaller.

However, in such a groove structure, an organic adhesive is used to fix the thick film circuit board within the case. Therefore, due to outgas from the adhesive, the vacuum chamber cannot be maintained at its full vacuum level, resulting in detection errors.

To solve this problem, it is possible to attach the thick film circuit board entirely externally, but if this is done, it becomes impossible to achieve miniaturization.

[Purpose of the invention]

An object of the present invention is to provide an absolute pressure reference type pressure transducer which is small in size and has good detection accuracy without being limited by the gas to be measured.

[Summary of the Invention] The present invention improves durability by facing the piezoresistance forming surface toward the vacuum chamber, and achieves miniaturization by providing the detection circuit inside the vacuum case. It is formed by thick film printing on the enamel part provided in a part of the
This is to obtain detection accuracy.

[Embodiments of the invention]

An embodiment of the present invention will be described using FIG. 1 and FIG. 2.

The central circular enamel part 2 of the pressed metal base J is plated 1! will be applied. On top of that, the entire surface is coated with a glass scope and sealed at a high temperature. The enameled part 2, which has been treated with Metsugi, is coated with glass in 7 stages). Since the glass is separately attached to the squirrel 1 and the fully bent base 1 in the glass coat removal section 3 other than that, no creeping is formed.

In this way, the portion was blown away! A thick film circuit 6 serving as a temperature compensation circuit and an amplification circuit is printed and formed on the enamel part 2 in the enamel substrate 4.

A pressure introduction pipe 8 is mechanically sealed in a hole made in the center of the base 1 with glass 10 VC. In addition, an input/output lead bin 7 and a vacuum pipe 9 are sealed in another hole with a glass 10.

A glass die 11 and a glue diaphragm 5 are joined onto the pressure introduction pipe 8. A recess is formed in the diaphragm 5 so that the glass die 11 and the glue 8 are connected to each other. The pressure introduction holes 12 are aligned. A piezoresistor is formed on the opposite side of the recessed portion of the diaphragm 5.

Connections are made between the piezoresistor on the diaphragm 5 and the thick film circuit 6, and between the thick film circuit 6 and the lead bin 70 by wire bonding.

After the connection of the circuit is completed, the metal cap 14 is resistance welded to the glass coat removed portion 3 of the enamel substrate 4, the vacuum is drawn using the vacuum pipe 9, and the pipe is sealed by resistance welding. A chamber 15 is formed.

According to the present invention, a Norikontetsubu and its compensation circuit,
] The circuit can be easily wall-sealed.

Another embodiment V of the present invention will be explained with reference to FIG.

This example is the same as the previous example up to the vacuum sealing stage, but it has a vacuum pipe 9 and a metal cap 14 is welded in a vacuum.
4-)-7--ni-ni,, IT:→1:1t1['R
h: It is installed by l-1 AI + low mounting.

According to the embodiment of the present invention, it is possible to simplify the vacuum fixing of the ridges and to increase the joint strength of the pressure introduction boat.

Another embodiment of the present invention will be described with reference to FIG.

In this embodiment, the absolute pressure reference pressure transducer 17 and the EG control valve 18 are integrated, and a part of the metal hem plate 1 of the hollow substrate 4 is processed by pressing, and the EG control valve 1B ( 1f: integrated with the structure.
E OR
Control) 11-4 [・ Negative pressure introduction passage 2 leading to F'18
Open and close 1.

According to this embodiment, the absolute reference pressure transducer 17 forms part of the structure of the actuator.

〔Effect of the invention〕

According to the present invention, the device is highly reliable, compact, and can improve detection accuracy.

[Brief explanation of drawings]

1 and 2 are a plan view and a sectional view of an embodiment of the present invention, 81'! FIG. 3 is a sectional view of another embodiment of the invention, and FIG. 4 is a top view of another embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Base, 4... Porrow board, 5... Noricon diantom, 6... Thick film circuit, 14... Gap. Representative Patent Attorney Akio Takahashi Figure 1 Figure 2

Claims (1)

[Claims] 1. A metal base with a processed enameled part at least in part, a semiconductor dianoram fixed to this base and having a piezoresistance formed on one side, and the above is formed by thick film printing on the hollow part. A pressure detection circuit, and a metal cover that is fixed to the base at a place other than the hollow part and forms a vacuum chamber inside, so as to cover the piezoresistive surface of the semiconductor dianoram and the pressure detection circuit. a pressure transducer 5 characterized in that it has;