JPS5852685Y2 - Metal envelopes for electronic components - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improved structure of a metal envelope for an electronic component such as a semiconductor device.

A can-sealed semiconductor device such as a power transistor has a structure as shown in FIGS. 1 and 2, for example.

In the figure, 1 is a metal stem, and lead wires 5, 5 made of iron-nickel alloy are passed through glass 4, 4 to through holes 3, 3 of a stem board 2, which is made by punching out a relatively thick iron plate into an approximately diamond shape.
are sealed in an airtight and insulating manner.

A semiconductor element 6 is soldered to the center of the upper surface of the stem substrate 1, and the lead wires 5, 5 and the electrodes of the semiconductor element 6 are connected by thin connecting wires 7, 7.

Then, a metal cap 8 made of iron is placed on top, and the flange portion 9 is resistance welded to the upper surface of the stem substrate 2 for sealing.

By the way, in order to perform resistance welding between the stem substrate 2 and the metal cap 8, generally an annular projection 10 is formed on the lower surface of the flange portion 9 of the metal cap 8, as shown in FIG. By concentrating the current, we are able to reliably perform resistance welding with as little current as possible.

However, due to a dimensional difference between the inner diameter of the component receiving hole of the welding jig (not shown) and the outer diameter of the metal cap 8, when the tip of the convex part 10 comes into contact with the stem board, the metal cap 8 may become attached to the stem board. 2, the positional relationship between the metal cap 8 and the stem substrate 2 may be shifted, resulting in poor appearance, as shown in FIG.

The present invention was proposed in consideration of these points, and includes forming a convex portion with a height h and a tip angle α on one side of the stem substrate and the metal cap facing each other, and a convex portion with a depth d on the other side. The present invention is characterized in that a recess is formed in which the angle β is smaller than the above and the angle β is larger than the α, and the protrusion is fitted into the recess and resistance welded.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 shows an exploded longitudinal sectional view before resistance welding, and FIG. 6 shows an enlarged longitudinal sectional view of the main parts.

In the figure, parts that are the same as those in FIGS. 1 and 2 are given the same reference numerals, and their explanations will be omitted.

In the present invention, an annular recess 11 is formed on the upper surface of the stem substrate 2 facing the protrusion 10 of the metal cap 8.

As shown in FIG. 6, the height of the convex portion 10 and the depth d of the concave portion 11 are set in a relationship of had.

Further, the tip angle α of the convex portion 10 and the angle β of the concave portion 11 are set in the relationship α<β, as is clear from FIG.

Therefore, when the convex portion 10 is fitted into the concave portion 11,
As shown in the figure, the lower surface 9a of the flange portion 9 of the metal cap 8 is raised from the upper surface 2a of the stem substrate 2.

Further, except for the contact portion between the tip of the protrusion 10 and the bottom of the recess 11, the protrusion 10 and the recess 11 are separated from each other.

With this configuration, when resistance welding the stem board 2 and the metal cap 8, the convex portion 10 can concentrate the current, and not only can welding be performed reliably with a small amount of current, but also the tip of the convex portion 10 can be welded reliably with a small amount of current. When the part melts, the unmelted shaft part just above the tip enters the recess 11, so the metal cap 8 will not slip on the top surface of the stem substrate 2, and the stem substrate 2 and the metal cap 8 will be separated. are welded in the correct relative positions, resulting in a can-sealed semiconductor device with high commercial value.

In addition, although the above-mentioned example explained the case where the upper surface of metal stem 1 was a flat surface, for example, it is called coining,
It can also be applied to metal stems in which the center part of the upper surface is thicker than the peripheral parts, or metal stems in which a heat dissipating material such as copper is fitted and fixed in place for soldering semiconductor elements.
Alternatively, the present invention can also be applied to a metal stem in which an iron welding ring is fixed to the welding location of a metal cap on a stem substrate with good thermal conductivity such as copper.

Furthermore, in the above embodiment, the case where the protrusion 10 is formed on the metal cap 8 and the recess 11 is formed on the metal stem 1 is explained, but it is also possible to form the protrusion on the metal stem 1 and the recess on the metal cap 8. Good too.

The present invention can be applied not only to semiconductor devices but also to other electronic components.

As described above, the present invention forms a convex portion with a height h and a tip angle α on one side of the opposing position of the metal stem and the metal cap, and has a depth d smaller than the above and on the other side. Since a recess with an angle β larger than α is formed and resistance welding is performed with the protrusion fitted into the recess, the protrusion concentrates the current and ensures reliable welding with a small amount of current. This has the effect that the metal stem and the metal cap can be fixed in the correct relative position.

[Brief explanation of drawings]

Figure 1 is a partially cutaway plan view of the metal cap of a can-sealed semiconductor device, Figure 2 is a vertical sectional view taken along line III in Figure 1, and Figure 3 is an exploded view of the conventional device before resistance welding. 4 is a plan view showing misalignment between the metal stem and metal cap that occurs in a conventional device; FIG. 5 is an exploded view of a can-sealed semiconductor device according to an embodiment of the present invention before resistance welding. FIG. 6 is an enlarged longitudinal sectional view of main parts in an assembled state before resistance welding. 1... Metal stem, 2... Stem substrate, 3, 3... Through hole, 4, 4... Glass, 5, 5... ... Lead wire, 6 ... Semiconductor element, 7, 7 ... Connection thin wire, 8 ... Metal cap, 9 ... Flange part, 10 ...・・・
... Convex portion, 11... Concave portion.

Claims (1)

[Scope of utility model registration request] In a device in which a metal cap is resistance welded to a metal stem and an electronic component element is housed inside, a convex portion with a height h and a tip angle α is formed at one of the opposing positions of the metal stem and the metal cap. At the same time, a concave portion having a depth d smaller than the above and an angle β larger than the α is formed on the other side, and the convex portion is resistance welded with the convex portion fitted into the concave portion. metal envelope.