JPS6032768Y2 - airtight terminal - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an airtight terminal used in a stem for a semiconductor device, etc.

For example, conventional examples of airtight terminals used in the stems of high-power semiconductor devices such as high-power transistors are shown in Figures 1 and 2.
As shown in the figure, 1 is a copper stem board, 2 is a stem board 1
3 is a lead outlet hole drilled in the stem board 1; 4 is an iron eyelet that is fitted into the lead outlet hole 3 and caulked, and then brazed; 5 is a lead wire; 6 Reference numeral 4 indicates a glass through which a lead wire 5 passes through the eyelet 4 and seals the same airtightly, and 7 indicates a stem mounting hole formed at both ends of the stem substrate 1.

A semiconductor pellet (not shown) is mounted on the center part 1a of the stem board 1 surrounded by the welding ring 2, and the semiconductor pellet and the lead wire 5 are connected with a thin metal wire. A metal cap 8 as shown in is welded for airtight sealing.

Note that the welding ring 2 is used as an intermediate member for welding because it is difficult to directly resistance weld the metal cap 8 to the copper stem substrate 1.

Also, the welding ring 2 is sometimes brazed on the flat surface of the stem board, but the welding ring 2 is sometimes brazed on the flat surface of the stem board.
In order to improve the positioning and brazing, a ring-shaped groove 9 is carved on the stem substrate 1 as shown in Fig. 2, and the welding ring 2 is fitted into this groove 9 and brazed. ing.

Alternatively, as shown in FIG. 3, for example, the center part 1a' of the stem board 1 is shaped higher than the periphery, and the welding ring 2 is fitted and brazed on the outer peripheral surface of this center part la'. ing.

By the way, the welding ring 2 has conventionally been brazed in the following manner.

For example, this has been done by interposing a plate-shaped or linear brazing material between the stem substrate 1 and the welding ring 2 and heating and melting it.

However, since plate-shaped beams are manufactured using a punching press, they are difficult to form, and they have the disadvantage of poor material utilization and are expensive.Also, rod-shaped soldered wood is easy to form, eliminates waste, and is inexpensive. The welding ring 2 was easily deformed during melting, did not flow evenly between the welding ring 2 and the stem substrate 1, and brazing sometimes resulted in defective parts, resulting in poor reliability.

Further, as shown in FIG. 4, the welding ring 2 is fitted into the groove 9 of the stem substrate 1, and the linear brazing material 10 is inserted into the gap between the outer peripheral surface of the welding ring 2 and the groove 9 and heated. A method has been proposed in which molten brazing metal is poured into a minute gap between the welding ring 2 and the groove 9 by capillary action.

However, the work of shaping the linear axle material 10 into a ring shape and inserting it into the gap between the welding ring 2 and the groove 9 was complicated and the workability was poor.

Alternatively, as shown in FIG. 5, a welding ring 2 is fitted into the protruding central portion 1a of the stem base plate 1, and then a linear brazing material 10' is arranged along the outer peripheral surface of the welding ring 2. A method of heating and melting this has also been proposed.

In this case, the linear brazing material 10' is relatively easy to arrange, but the brazing material 10' spreads outward due to heating during brazing, and the molten brazing material spreads between the welding ring 2 and the stem substrate 1. There was a risk that the water could spread outside without flowing into the gap, making it unreliable.

Further, the brazing of the eyelet 4 sometimes has the same problem as above.

The present invention improves and eliminates the above-mentioned conventional drawbacks by forming a notch-like recess in the part of the copper-based stem board that is in contact with the peripheral surface of the iron-based ring-shaped member. To provide an airtight terminal in which a brazing material is arranged and brazed by pouring the brazing material from a recessed part between a stem substrate and a ring by capillary action.

The present invention will be explained below with reference to the drawings.

For example, an example applied to an airtight terminal used in a stem for a semiconductor device is shown in FIGS. 6 to 8. Reference numeral 11 is a copper stem substrate, 12 is a welding ring as an example of an iron ring-shaped member, and 13 is a lead wire. , 14 is an eyelet which is another ring-shaped member made of iron, and 15 is a lead wire sealing glass.

The stem board 11 is of a type in which a central portion 11a is circular and high, and a welding ring 12 is fitted into this central portion 11a and brazed.

A feature of the present invention is that concave portions 16 are formed by cutting out key points, for example, three locations, on the side surface of the central portion 11a that joins with the inner circumferential surface of the welding ring 12.

Then, using this recess 16, the welding ring 12 is brazed to the stem substrate 11 in the following order.

First, the welding ring 12 is fitted so as to surround the central portion 11a of the stem substrate 11, and the welding ring 12 is positioned and placed on the stem substrate 11 (see FIG. 9).

Next, while holding the stem board 11 horizontally, the recess 16
A bar-shaped brazing material 17 such as silver solder is inserted into the recess 16 (see FIG. 10).

In this case, the rod-shaped brazing material 17 may be stably held from the outside with a graphite jig or the like.

Next, the whole is placed in a heating chamber and the rod-shaped brazing material 17 is heated and melted.

Then, the melted brazing metal 17' flows from the recess 16 into the welding ring 1.
2 and the stem substrate 11 due to capillary action, and the welding ring 12 is brazed (see FIG. 11).

At this time, if the amount of bar-shaped brazing material 17 is greater than 8 required to braze the welding ring 12, the excess brazing material will remain in the recess 16.

Furthermore, by brazing the welding ring 12 using the capillary action of the brazing material, the entire surface can be brazed uniformly.

Next, modifications of the present invention are shown in FIGS. 12 to 14,
To explain this, FIG. 12 shows an example in which the height of the recess 16' is set to the height at which the central portion 11a of the stem substrate 11 protrudes, and by doing so, the stability of the bar-shaped brazing material 17 is improved.

Further, FIG. 13 shows an example of a type in which a ring-shaped groove 18 is carved on the stem board 11, and the welding ring 12 is fitted into this groove 18 and brazed. In this case, a recess is formed on the inner peripheral surface of the groove 18. 1
Form 6″.

Next, in FIG. 14, the central part 11a of the stem board 11 is made to protrude, a groove 19 is formed on the stem board 11 along the central part 11a, and a welding ring 12 is inserted into the groove 19 so as to surround this central part 11a. In this case as well, recesses 16'' are provided at important points in the central portion 11a that contacts the welding ring 12.

In the above embodiments, the welding ring 2 is brazed, but the eyelet 4 can be brazed in the same manner.

Further, the stem substrate 1 may be formed of a copper alloy containing copper as a main component, and the welding ring 2 and/or the eyelet 4 may be formed of an iron alloy containing iron as a main component.

Furthermore, the present invention is not limited to the hermetic terminal of a stem for a semiconductor device, but can be applied to any device in which an iron-based ring is brazed to a copper-based stem substrate.

Furthermore, although the brazing material used for brazing has been described as being rod-shaped, it is also possible to place, for example, granular brazing material into the recess and heat it for brazing, and the brazing material is not limited to rod-shaped brazing material.

As explained above, according to the present invention, it is only necessary to place a rod-shaped brazing material in the recess of the copper-based stem board and heat it, making it easy to braze iron-based ring-shaped members. Therefore, inexpensive rod-shaped brazing material can be used.

In addition, since brazing is performed by capillary action of the melted brazing material, it is possible to braze evenly on the surface, improving the reliability of brazing, and preventing erosion of the brazing material from the ring-shaped member. The ring-shaped member does not tilt due to protrusion or brazing defects, and the appearance improves.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an example of a conventional airtight terminal, Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1, Fig. 3 is a cross-sectional view showing a modification of Fig. 2, and Figs. Fig. 5 is a cross-sectional view of a main part of the brazing material of a conventional welding ring, Fig. 6 is a plan view showing an embodiment of the airtight terminal according to the present invention, and Fig. 7 is Fig. 6B-
8 is an exploded perspective view of the airtight terminal shown in 6.
9 to 11 are partially enlarged cross-sectional views of the main parts of the brazing material shown in FIG. FIG. 4...Ring-shaped member (eyelet), 11...
... Stem board, 12 ... Ring-shaped member (
welding ring), 16.16', 16'' 16 nt...
...Concavity, 17... (rod-shaped) brazing material.

Claims (1)

[Scope of utility model registration request] In a product in which an iron-based ring-shaped member is brazed to a copper-based stem board, recesses are formed at key points on the stem board in contact with the circumferential surface of the ring-shaped member, and brazing material is placed in these recesses. An airtight terminal characterized in that a ring-shaped member is brazed to a stem board.