JPH0355874Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a technology for improving airtight terminals used in pressure sensors.

Prior Art First, a conventional pressure sensor 1 will be explained based on FIG. 4. 2 is an airtight terminal, for example, a thick-walled
A through hole 4 for conducting pressure is formed in the center of a disk-shaped metal outer ring 3 made of Fe-Ni-Co alloy, etc.
A suitable number of through holes 5, 5 for sealing the leads are formed around it, and leads 7, made of Fe-Ni-Co alloy are inserted into these through holes 5, 5 through borosilicate glasses 6, 6. 7 is sealed, and the center part of the lower surface of the metal outer ring 3 is sealed.
A pressure impulse pipe 8 made of Fe-Ni-Co alloy is brazed. Reference numeral 9 denotes a ring-shaped pedestal made of Si, for example, which is fixed to the center of the upper surface of the metal outer ring 3. A pressure-sensitive element 10 is mounted on this pedestal 9, and the pressure-sensitive element 10 is mounted on the pedestal 9.
electrodes are connected to leads 7,7. Reference numeral 12 denotes a cap fixed to the metal outer ring 3 by melting or the like, and the pressure sensor 1 is constructed in which a sealed space formed by the metal outer ring 3 and the cap 12 serves as a reference pressure space P (Japanese Patent Application Laid-open No. 1983-1993). Publication No. 89873).

However, in the above-mentioned airtight terminal 2, the pedestal 9 and the impulse tube 8 are brazed to the upper and lower surfaces of the metal outer ring 3, and the pressure-sensitive element 10 is brazed onto the pedestal 9, which are heated twice. In addition, since the expansion of the metal outer ring 3 and the expansion of the pedestal 9 do not match, there is a drawback that brazing the metal outer ring 3 and the pedestal 9 requires advanced technology and ingenuity.

Therefore, the inventor of the present invention proposed an airtight terminal 13 for a pressure sensor as shown in FIG. This airtight terminal 13 is formed by drawing a thin Fe-Ni-Co alloy plate to form a shell-shaped metal outer ring 14, and also overlaps a pressure impulse tube and a pedestal 16, which are longer than conventional ones. This is sealed with glass 18 for sealing the leads 17, 17. According to such an airtight terminal 13, when the leads 17, 17 are sealed to the metal outer ring 14 with the glass 18, the impulse tube 15 and the pedestal 16 are sealed to the metal outer ring 14 together with the leads 17, 17. There are advantages to being able to do so. In this way, it is only necessary to braze the pressure sensitive element 10 to the pedestal 16, and the problem of expansion can be solved. However, the mounting surface of the pressure sensitive element 10 on the pedestal 16 still requires There was room for improvement.

Problems to be solved by the invention: In glass-sealing the impulse tube 15, the pedestal 16, and the leads 17, 17 to the metal outer ring 14, a carbon jig is used as shown in FIG. The metal outer ring 14 is fitted upside down into the recess 20 formed in the metal plate 19, and a glass tablet 18' for sealing, which is made by kneading an organic binder into the glass powder and calcining the mixture after molding, is attached to the metal. Outer ring 1
A pedestal 16 is placed in the center hole of the glass tablet 18', and a pressure impulse tube is set on the pedestal 16.
7 is set in a predetermined position, the whole is heated to melt and seal the glass tablet 18'9. At this time, the carbon jig 199 is connected to the SI pedestal 16. reacts chemically, and the contact surface of the base 16 with the carbon jig 19, that is, the mounting surface 10a of the pressure-sensitive element 10, becomes Si
A porous compound SiC is generated by the reaction formula C→SiC, and the element mounting surface 16a becomes a rough surface, making it difficult to obtain smoothness.Therefore, there is room for improvement in that mounting the pressure sensitive element 10 becomes difficult. Ta.

Means for Solving the Problems The present invention solves the above problems by making the pedestal for supporting the pressure-sensitive element made of glass, which has a higher softening point than the glass for sealing, and by making the pedestal, along with the leads, out of metal. It is distinctive in that the ring is sealed with glass.

Operation According to the above characteristic structure, it is superior in terms of brazing and expansion compared to the conventional method, and since the pedestal is made of glass, there is no reaction between the glass pedestal and the carbon jig, making it easier to attach the element. If the surface can be left as it is at the initial stage and the element mounting surface is made of a highly smooth surface, for example a mirror surface, mounting of the pressure sensitive element becomes easier.

Embodiment Hereinafter, embodiments of the present invention will be explained based on the drawings. Fig. 1 shows an airtight terminal 2 of an embodiment of the present invention.
2 shows a pressure sensor 21 using the pressure sensor 2. This airtight terminal 22 is the same as that shown in FIG. 5, except that the pedestal 23 is made of glass with a higher softening point than the sealing glass 18, so the same parts as in FIG. are given the same reference numerals and their explanations will be omitted. The pressure sensitive element 10 is fixed on the pedestal 23 on this airtight terminal 22, and the electrodes of the pressure sensitive element 10 are connected to the lead wires 17, 17 with wires 11, 11. Thereafter, a cap 24 is sealed to the metal outer ring 14 with the pressure-sensitive element 10 incorporated therein.

The impulse pipe 15, the leads 17, 17, and the pedestal 2
The glass sealing of No. 3 is the same as that shown in FIG. 6 and described above with respect to the airtight terminal 13 of FIG. 5. That is, as shown in FIG. 2, a jig 19 made of carbon
The metal outer ring 14 is turned upside down and fitted into the recess 20 formed in the metal outer ring 14, and the glass tablet 18' is placed inside the metal outer ring 14, and the pedestal 23 is inserted into the central hole of the glass tablet 18'. and impulse pipe 1
5 and the leads 17, 17 are set in predetermined positions, and the whole is heated to melt the glass tablet 18'. The material of the glass pedestal 23 is as follows:
It is also important to select a glass that has a softening point higher than that of the glass 18 used to seal the leads 17, 17 to the metal outer ring 14, and whose expansion coefficient is close to that of the pressure-sensitive element 10. Glass 18 has a softening point of 705℃ and an expansion coefficient of 46×10-7/
When using borosilicate glass, the glass for the pedestal 23 has a softening point of 820℃ and an expansion coefficient of 32×10−
All you have to do is choose glass 7/, and in any case,
It is desirable that the difference in softening point between the sealing glass 17 and the glass for forming the pedestal 23 is 50° C. or more. In this way, if the pedestal 23 is made of glass and its softening point is set higher than the softening point of the sealing glass 18, not only will the pedestal 23 not be deformed by the heat during sealing, but it will also be made of glass. The pedestal 23 does not react with the carbon jig 19, and the pedestal 23
The mounting surface 23a of the pressure sensitive element 10 does not become a rough surface.

The pressure sensor 21 having the above configuration closes the pressure path of the measured pressure using the pressure sensing element 10, and converts the sealed space formed by the metal outer ring 14 and the cap 24 into the reference pressure space P. However, as shown by the imaginary line in FIG. For pressure sensors of the type that measure the difference between
The airtight terminal 2 is sealed with glass 18 along with 7 and 17.
7, the pressure sensitive element 10 is brazed to the pedestal 28, and the cap 29 connecting the pressure tube 30 to the airtight terminal 27 is sealed;
The present invention can be implemented by configuring the sealed space formed by the pedestal 28 and the pressure sensitive element 10 as the reference pressure space P.

Effects of the invention As explained above, according to the invention, the pedestal for supporting the pressure-sensitive element is glass-sealed to the metal outer ring together with the leads, so unlike conventional methods, the impulse tube and pedestal are brazed to the metal outer ring. In addition, there is no need for the inconvenience of brazing due to the difference in expansion between the metal outer ring and the pedestal, which requires advanced technology and ingenuity.

Since the pedestal is made of glass having a higher softening point than the sealing glass, when the pedestal and the lead are sealed with glass using a carbon jig, the pedestal may be softened and deformed, and the pedestal and the carbon There is no reaction with the jig, so the element mounting surface can be left as it is at the initial stage.If the element mounting surface is made of a highly flat surface, such as a mirror surface, mounting the pressure sensitive element is simple and easy. can be done.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a pressure sensor using an airtight terminal according to an embodiment of the present invention, Fig. 2 is a cross-sectional view showing the assembled state of the sensor of Fig. 1 before glass sealing, and Fig. 3 is a cross-sectional view of a pressure sensor using an airtight terminal according to an embodiment of the present invention. FIG. 7 is a cross-sectional view of a pressure sensor according to another embodiment. Fig. 4 is a sectional view of a conventional pressure sensor, Fig. 5 is a sectional view of an improved hermetic terminal which is the premise of the present invention, and Fig. 6 is an assembly of the airtight terminal of Fig. 5 before glass sealing. It is a sectional view showing a state. 14... Metal outer ring, 15, 25, 30... Impulse tube, 17... Lead, 18... Glass for lead sealing, 23... Pedestal for supporting element.

Claims (1)

[Claims for Utility Model Registration] (1) The pedestal for supporting the pressure-sensitive element, which is connected to the pressure-sensitive element, is made of glass having a higher softening point than the sealing glass, and the pedestal, together with the lead, is made of non-metallic material. An airtight terminal for pressure sensors characterized by a ring sealed with glass. (2) The airtight terminal for a pressure sensor according to claim 1, wherein the difference in softening point between the sealing glass and the glass forming the pedestal is 50° C. or more.