JP2744501B2 - Hermetic terminal and manufacturing method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetic terminal used for a pressure sensor, a semiconductor device, and the like, and a method for manufacturing the same.

[Prior Art] There are various types of hermetic terminals, one of which is used for a pressure sensor as shown in FIG.

In this pressure sensor, a pipe 3 for introducing gas is brazed, for example, to a central opening of a metal outer ring 1, for example, a ventilation hole 2, and a lead 5 is inserted into a plurality of lead insertion holes 4 around the same. Then, an airtight terminal sealed with glass 6 is used. The airtight terminal is then provided with a gold plating layer 11 by applying gold plating to the surface of the metal outer ring 1 and the pipe 3 to which the silver brazing is applied. While firmly fixing to the periphery,
A diaphragm 8 for pressure detection is hermetically attached to the silicon pedestal 7 and wire-bonded to the lead 5, and a cap 9 is placed on the diaphragm 8 and hermetically fixed around the metal outer ring 1.

The hermetic terminal used in this pressure sensor has the surface of the metal outer ring 1 covered with a gold plating layer 11, and the silicon pedestal 7 joins the silicon pedestal 7 and the gold plating layer 11 by heating. It is air-tightly fixed to the periphery of the ventilation hole 2 of the outer metal ring 1 by a eutectic (not shown) of gold-silicon formed at the interface.

[Problems to be Solved by the Invention] However, in the hermetic terminal, when the pipe 3 is brazed with silver to the ventilation hole 2 of the metal outer ring 1 and gold-plated, the silver when the silicon pedestal 7 is fixed is heated. The silver component in the brazing portion 12 easily diffuses into the gold plating layer 11, and the silver brazing portion
12 Surface discoloration or gold plating layer of silver component in silver braze 11
The bonding strength tends to decrease due to the decrease due to diffusion into the pipe, and in some cases, there is a problem that the pipe 3 falls off.

Therefore, before forming the gold plating layer 11, the metal outer ring 1
A nickel plating layer (not shown) is formed by applying an electroless nickel plating to the surface of the pipe 3 having the metal outer ring 1 silver-brazed to the surface of the pipe 3, and then a gold plating layer 11 is formed. Although the diffusion of the copper component in the part 12 to the gold plating layer 11 may be prevented, the number of work steps for forming the nickel plating layer increases, which causes a problem that the cost increases.

Further, since the metal outer ring 1 and the pipe 3 are silver-brazed, it is necessary to prepare both parts in a pair, and there is a problem that the number of parts increases, and it is difficult to manage the storage location of each part. is there.

A similar problem also occurs, for example, in a silver brazing portion between a metal outer ring and a ground lead in a surface acoustic wave element or a stem for a semiconductor device.

Means for Solving the Problems In order to solve the above problems, the hermetic terminal of the present invention is a lead of a molded body in which a metal outer ring having a lead insertion hole and an auxiliary member attached to the metal outer ring are integrated. The lead is inserted through the insertion opening, each lead is sealed with glass, and the surface of the molded body is directly covered with a gold plating layer.

Also, the method for manufacturing a hermetic terminal of the present invention comprises forming a molded body in which a metal outer ring having a plurality of lead insertion holes and an auxiliary member attached to the metal outer ring are integrated, and After the lead is inserted into each of the plurality of lead insertion holes of the ring to seal the glass, the molded body is directly subjected to gold plating, and the surface is directly covered with a gold plating layer.

[Operation] In the hermetic terminal having the above-described configuration, the metal outer ring and the auxiliary member attached to the metal outer ring are integrally formed, so that it is not necessary to separately prepare an auxiliary member, and the direct plating layer on the surface is eliminated. Even if it is covered with, since the connecting portion between the auxiliary member and the metal outer ring is not joined by the silver brazing material as in the conventional case, the copper component in the silver brazing material diffuses into the gold plating layer and discolors,
The auxiliary member does not fall off due to a decrease in the connection strength.

Further, in the present invention, after forming a molded body in which the metal outer ring and the auxiliary member attached to the metal outer ring are integrated, the lead is inserted through the plurality of lead insertion holes of the metal outer ring of the molded body. Glass sealing. When the surface of the molded body is coated with a gold plating layer by directly applying gold plating to the molded body in which each lead is sealed with glass, the connecting portion between the auxiliary member and the metal outer ring is not joined by the silver brazing material. There is no fear that the copper component in the brazing material diffuses into the gold plating layer to cause discoloration of the connection part, or that the connection strength is reduced and the auxiliary member falls off.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a hermetic terminal according to one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part of the hermetic terminal. The hermetic terminal shown in the figure is, for example, an hermetic terminal used for a pressure sensor, and is a molded body in which a metal outer ring 21 and a pipe as an auxiliary member 22 attached to the metal outer ring 21 are integrally formed.
Except for the provision of 20, the structure has the same structure as the conventional hermetic terminal described above.

That is, the metal outer ring 21 of the molded body 20 has, for example, a vent hole 2 formed at the center thereof as in the related art, and a plurality of (four in this embodiment) lead insertion holes 4 are formed around the vent hole 2. A perforated step 23 is provided around the outer peripheral edge for fixing the cap 9. On the other hand, the auxiliary member 22 is a gas introduction pipe connected and integrated with the lower peripheral edge of the ventilation hole 2. Then, the leads 5 are inserted into the respective lead insertion holes 4 of the metal outer ring 21 of the molded body 2 and mounted on the glass 6 by glass. Further, as shown in FIG. It is covered with a gold plating layer 24.

As a method of manufacturing the hermetic terminal having the above configuration, first, although not shown, a mold in which the metal outer ring 21 and the auxiliary member 22 are integrated is formed, and metal powder is filled in the mold and heated under pressure. The compact 20 is formed by a so-called powder metallurgy method.
At this time, since the connecting portion between the metal outer ring 21 and the auxiliary member 22 is integrally formed, it is not necessary to perform connection by performing silver brazing as in the related art, and the number of steps can be reduced.

When the molded body 20 is molded, the leads 5 are inserted into the respective lead insertion holes 4 of the metal outer ring 21, and the glass 5 is inserted into the leads 5.
Are externally fitted and heated and melted, and each lead 5 is glass-sealed in the lead insertion hole 4.

When each lead 5 is glass-sealed in the lead insertion hole 4,
The molded body 20 is subjected to gold plating, and a gold plating layer 24 is laminated on the surface to manufacture an airtight terminal. At this time, since the connecting portion between the metal outer ring 21 and the auxiliary member 22 is integrated, the surface of the molded body 20 is directly covered with the gold plating layer 24 so that silver brazing is not performed as in the related art. As in the past, discoloration occurs at the connection part, and the silver component in the silver brazing material is changed to the gold plating layer 24.
It does not diffuse into the inside and lowers the connection strength of the connection portion at all, so that the airtight terminal is free from the possibility that the auxiliary member 22 falls off the metal outer ring 21.

The hermetic terminal of the present invention manufactured by the above manufacturing method is used, for example, for a pressure sensor. In this assembly, as shown by a chain line in FIG. 1, the silicon pedestal 7 is placed on the periphery of the ventilation hole 2 of the metal outer ring 21 of the molded body 20, and the gold plating layer 24 on the surface of the molded body 20 is heated. The gold component and the silicon component of the silicon pedestal 7 form a gold-silicon eutectic layer (not shown) at the joint interface, and the silicon pedestal 7 is hermetically fixed to the metal outer ring 21. At this time, if the thickness of the gold plating layer 24 is smaller than 1.2 μm, it is difficult to form a sufficient gold-silicon eutectic layer, and the fixing strength and airtightness of the silicon pedestal 7 may be reduced. The thickness of the plating layer 24 is preferably at least 1.2 μm.

When the silicon pedestal 7 is airtightly fixed to the metal outer ring 21,
A diaphragm 8 for pressure detection is hermetically attached to the silicon pedestal 7. Then, each terminal of the diaphragm 8 and each lead 5 are wire-bonded, a cap 9 is put on the terminal, and airtightly fixed at the peripheral step 23 of the outer metal ring 21 to assemble the pressure sensor.

As described above, the hermetic terminal used for the pressure sensor is a molded body 20 in which the metal outer ring 21 and the auxiliary member 22 are integrally molded. The operation of joining the two members is not required, so that the number of steps can be reduced, the number of parts can be reduced by half, and the parts can be easily managed. Furthermore, since the connecting portion between the metal outer ring 21 and the auxiliary member 22 is integrally connected without performing silver brazing, nickel plating is performed before gold plating is performed on the surface, and the copper component of the silver brazing material is reduced. There is no need to form a nickel plating layer for preventing diffusion to gold plating, and the number of steps can be further reduced.

Note that the present invention is not limited to the above-described hermetic terminal for the pressure sensor, but may be an hermetic terminal as shown in FIG. The hermetic terminal is, for example, a hermetic terminal for a surface acoustic wave element, and the molded body 30 of the hermetic terminal is integrally formed with the outer metal ring 31 and the lower end of the outer metal ring 31 by, for example, powder metallurgy. The auxiliary lead 32 is formed of a ground lead, and the entire surface is directly covered with a gold plating layer 33.

In the above-mentioned hermetic terminal, after the seal lead 35 is inserted into the lead insertion hole 34 perforated in the metal outer ring 31 of the molded body 30 and sealed by the glass 36, the surface can be plated with gold. Therefore, it is possible to directly apply the gold plating to the integrated molded body 30 without attaching the auxiliary member 32 serving as the earth lead to the metal outer ring 31 by silver brazing as in the conventional case, and it is possible to reduce the number of steps in the same manner as in the above embodiment. And the number of parts can be reduced, and the connection strength of the connection portion between the metal outer ring 31 and the auxiliary member 32 is reduced, so that there is no fear that the auxiliary member 32 will fall off.

In the surface acoustic wave terminal using the hermetic terminal, the gold-silicon eutectic is formed by the gold plating layer 33 on the surface in the same manner as in the above embodiment by heating the silicon pellet 37 supported on the metal outer ring 31 and heated. The pellet 37 is formed and securely fixed, and is assembled with the cap 38 covered.

In the above embodiment, the compacts 20 and 30 were integrally formed by the powder metallurgy method, but the auxiliary members 2 integrated with the metal outer rings 21 and 31 were used.
If the protrusion length of 2, 32 is relatively short, it may be integrally formed by press working or the like. [Effect of the Invention] As is clear from the above description, according to the hermetic terminal of the present invention and the method of manufacturing the same, metal Since the outer ring and the auxiliary member are formed as an integral molded body, the work of joining both members as in the past is not required, reducing man-hours, reducing the number of parts, facilitating parts management, and improving the strength at the joint. There is no worry about decline. Furthermore, since the connecting portion between the metal outer ring and the auxiliary member is integrally connected without performing silver brazing as in the related art, nickel plating is performed before the surface is gold-plated, so that the silver brazing material is used. It is not necessary to prevent the copper component from diffusing into the gold plating layer, and the number of steps can be further reduced.

[Brief description of the drawings]

1 is a cross-sectional view of a hermetic terminal according to one embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of a main part of the hermetic terminal, and FIG. 3 is a cross-sectional view of a hermetic terminal according to another embodiment of the present invention. FIG. 4 is a sectional view of a conventional hermetic terminal. 4,34 Lead insertion hole, 5,35 Lead, 20,30 Molded body, 21,31 Metal outer ring, 22,32 Auxiliary member, 23,33 Gold plated layer.

Claims (2)

(57) [Claims] 1. A lead is inserted into the lead insertion opening of a molded body in which a metal outer ring having a lead insertion hole and an auxiliary member attached to the metal outer ring are integrated, and each lead is sealed with glass. An airtight terminal, wherein the surface of the molded body is directly covered with a gold plating layer. 2. A molded body in which a metal outer ring having a plurality of lead insertion holes and an auxiliary member attached to the metal outer ring are formed integrally, and a plurality of lead insertion holes of the metal outer ring of the molded body are formed. A method for producing a hermetic terminal, characterized in that a lead is inserted through each of the above-mentioned pieces, glass sealing is performed, and then the molded body is directly subjected to gold plating to cover the surface with a gold plating layer.