JPS58140620A - Manufacture of absolute pressure transducer - Google Patents

Abstract

PURPOSE:To improve the precision and sensitivity of measurement nearly at specific temperature by coating the outer edge of a lower unit with a glass layer and an upper unit with a glass adhesive and then mounting a piezoeresistance element, and carrying out vacuum heating and cooling under pressure while superposing both units. CONSTITUTION:The outer edge of the lower unit 2 is coated with the glass layer 8. The upper unit 1 is coated with paste of glass powder at a prescribed top surface position and the piezoresistance element 7 is mounted thereupon. On the lower unit 2, the upper unit 1 is superposed and in a furnace, they are heated under a vacuum to fuse the glass layer 8. Then, 400g/cm<2> gas is introduced into the furnace to strain the upper unit 1. At this time, the space 3 in the furnace is held under a vacuum by the sealing operation of the glass layer 8 and the element 7 has no strain because the glass layer 9 is in the fused state. In this state, cooling is performed and wiring, etc., are carried out to obtain the absolute pressure transducer which has high sensitivity and high precision nearly at 400g/cm<2> abolute pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a method of manufacturing an absolute pressure transducer using a piezoresistive element.

Conventionally, as an absolute pressure transducer characterized by miniaturization, at least a part of the outer wall of the closed case is made of a diaphragm-like elastic member, and a piezoresistive element is directly fixed to the elastic member, or an elastic member is used. The Ministry of the Invention and others have already proposed % Publication No. 117867 (Patent No. 117867), in which a part of the piezoresistive element is incorporated into
No. 5011) discloses a new bag light, and provides a new light by adding an improved tube thereto.

In an absolute pressure transducer, there are cases where the density near a specific pressure is 1 pm. Here, the specific pressure is, for example, a measured pressure suitable for an application specified by a customer.An example is when the pressure is applied to an air pressure needle or a filled gas pressure monitoring transmitter of a gas filled cable.

In this case, configuring the converter to operate with as much sensitivity as possible near a specific pressure is advantageous in terms of so-called high precision, since good temperature characteristics can be obtained and changes over time are small.

The sealed container may be filled with a certain amount of gas or kept under vacuum. In the case of a vacuum, the method of fixing the element to the elastic member is to form a sealed container and fix the element at the same time in a vacuum, or to fix the element to the elastic member in a non-vacuum and then fix it inside the container. ! There are ways to fix it using vc.

When a transducer manufactured using these methods is operated near a specific pressure that the user is trying to measure, a large strain will be applied to the element kcfi. Disconnection due to strain, non-tiim
If there is a risk of an increase in the m difference, the occurrence of creep, etc., and a decrease in the force operation sensitivity, it has the above-mentioned drawback 1 in that ellipticization cannot be achieved.

To overcome this drawback, there is a method of simultaneously frying the sealed container and fixing the element in gas at a pressure close to the VC1 specific pressure, but the converter manufactured using this method does not solve the above problem. However, due to the thermal expansion of the large gas that is currently being destroyed, m
It has the drawback that zero drift occurs when the temperature changes, and the tank pressure is not easy to adjust.

The present invention has been made in order to overcome the above-mentioned drawbacks inherent in the rice pressing technique, and therefore, the strain of the element becomes zero at a specific pressure for determining the L1 koji J of the present invention. Therefore, it is possible to realize a novel method for manufacturing a feed pressure transducer that can improve measurement n1 degrees and sensitivity at or near a specific pressure.

In order to achieve the above object, the method for manufacturing an absolute pressure transducer according to the present invention includes applying a glass layer to the upper surface of the outer edge of the lower unit and applying a glass layer to a predetermined position on the upper unit. ＆Adhesive is planted and a piezoresistance element is placed on it, and then the upper unit is placed on the 1# lower unit and introduced into a furnace and heated in a vacuum to form the glass layer. The bath is melted, and while the glass layer remains in a molten state, scum with a specific gauge pressure is introduced into the 61st century furnace to provide gold to the upper unit, and then the furnace is cooled until t in a pressure introduced state and brought to atmospheric pressure. The method includes a step of taking out the combined body of the lower unit and the upper unit to the outside after opening.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to a preferred embodiment thereof.

Figure 1 is a plan view of the absolute pressure transducer to which the present invention is applied, and Figure 82 is a # side view taken along line 2-21ii1 in Figure 111 and viewed in the direction of the arrow. In the figure, reference number 1 indicates an upper unit which is an elastic member, and the upper unit is assembled with a cylindrical lower unit 2 to form a closed container having a closed space 3.

The upper unit 1 has a structure in which a machine-like A14 is provided on a disk-shaped thick plate member, the bottom surface of #I4 is made thin to have elasticity, and cylindrical projections 5 and 6 are made to stand upright from the bottom surface.

When the external pressure P is applied, the central island portion 10 is slightly bent in the direction of the arrow (@211d) due to the elasticity of the thin wall portion, and the cylinder 5.6 is tilted inward and its upper surface is slightly displaced in the direction of the arrow.

7 is a piezoresistive element fixed to the upper surface of the upper unit, and functionally serves as an electrode part (fixed part) 71.73.7
5 and an element section 72.14.

The back surfaces of the electrode parts 71, 73, and 75 serve as fixed areas, respectively.
They are fixed to the upper surfaces of the central island portion 10, the cylindrical projection 6, and the outer edge 11i311 of the upper unit 1, respectively, by, for example, glass bonding.

- When the upper peak of the protrusion 6 is slightly displaced inward by the external pressure P, the element portion 72 is compressed and its resistance value decreases, and the element portion 74 is pulled and its resistance value increases. In this way, an output signal corresponding to the pressure P is obtained.

In order to improve the stability Wl of the specific pressure transducer of the above-mentioned absolute pressure transducer in the vicinity of a specific pressure, the present invention -
In line with the purpose described above, measures were taken during the assembly process to provide a certain deviation between the distortion of Atsuba Unit 1 and the distortion of the element. J! In this embodiment, for example, the relative pressure (differential pressure from sub-atmospheric pressure) is 200 to soo g/cm.
If the required pressure is within the measurement range, the process is designed to provide a deviation strain corresponding to the gauge pressure of 400 Va as the center value. Work on this! Written in IA, it is as follows.

(1) A glass layer 8 is coated on the upper surface of the outer edge of the lower unit 2.

(2) Upper unit 1. Apply a paste made by adding liquid to glass powder (glass adhesive) to the upper E11 predetermined position, and place the piezoresistive element on top.

(3) Place the upper unit 1 on top of the lower unit 2, introduce it into a furnace, and heat it in a vacuum to melt the glass layer 8. At this time, the paste-like glass also evaporates into a molten glass layer 9, and the closed space 3 becomes a true 9.

(4) Gas with a gauge pressure of 40,077 kh" is introduced into the furnace up to the trench where the glass layer 8 is in a molten state, and strain is applied to the upper unit 1. At this time, the space 3 is kept in a vacuum due to the sealing action of the glass layer 8. Since the glass layer 9 is in a bath-molten state, the element is maintained without distortion.

(5) Cool the furnace until pressure is introduced. At this time, the glass that is the adhesive layer of the element is solidified, the internal hermetically sealed space 3 is maintained at vacuum, the outside is maintained at the introduced pressure, and the strain of the element is zero. After that, it is taken out to the outside, and the wiring and other wiring of the elements are completed.

The device manufactured by Kamichikosu has zero strain at a relative pressure of 4001/l, and even when exposed to atmospheric pressure, the strain remains at -400f.
/aIk'', so there is no risk of disconnection even if the body of the upper unit is thinned and configured with high sensitivity.Also, since the distortion is zero at the center of the defined range, one-line property is eliminated. Since the sealed chamber 3 is in a vacuum, temperature drift does not occur, and in the case of manufacturing an atmospheric pressure converter, the introduction pressure of 1 liter in (4) above may be set to atmospheric pressure.

As described in detail above, according to the present invention, it is possible to realize an absolute pressure transducer that is highly sensitive and highly accurate near a specific pressure with a simple structure and one manufacturing process, which improves technical and economical advantages. The effects are extremely large.

[Brief explanation of drawings]

Figure @1 is a plan view showing an example of a nine-absolute pressure transducer to which the present invention is applied, and Figure ll12 is a sectional view taken along the 2-2 layer of Figure ta1 and viewed in the direction of the arrow. 100. Upper unit, 210. Lower unit, 30
．． . Closed space, 490. Groove, 5.6600 Cylindrical projection, 70
0. Piezoresistive element, 71.73.75. ,,electrode section,
72.74. , , element section, 860. Glass layer, s@@a
91 layers of molten gas molten layer, central island portion, 11. ,, outer edge patent applicant Okura Electric Co., Ltd. Patent attorney Yutabe Kumagai No.

Claims (1)

[Claims] A glass layer is applied to the upper outer edge of the lower unit, and a glass adhesive is applied to a predetermined position on the upper unit 11j, and a piezoresistive element is placed thereon.
Place the upper unit on the lower unit, introduce it into a furnace, and heat it in a vacuum to melt the glass dove described in 11tI,
Gas with a constant gauge pressure of KIp# is introduced into the furnace to the trench where the glass layer is in a molten state to give a strain to the upper unit, and then the furnace is cooled in the pressure introduced state, and then released to atmospheric pressure.
k- A method for manufacturing an absolute pressure transducer, characterized in that a combined body of a lower unit and a seven-piece unit is taken out to the outside.