US2877393A - Semi-conductor device - Google Patents

Description

March 10, 1959 w. A. RVOOVERS 2,877,393

SEMI-CONDUCTOR DEVICE Filed Dec. 9, 1954 INVENTOR WILHELMUS ANTONIUS ROOVERS United States Patent SEMI-CONDUCTOR DEVICE Wilhelmus Antonius Roovers, Eindhoven, Netherlands, assignor, by mesne assignments, to North American Philips Company, Inc., New York, N. Y., a corporation of Delaware Application December 9, 1954, Serial No. 474,257

Claims priority, application Netherlands December 22, 1953 3 Claims. (Cl. 317-234) The invention relates to a semi-conductor device, and in particular to an electrode system comprising a semiconductive body arranged in an envelope consisting at least in part of glass, a plurality of leads being sealed into this glass part. Such a device may be a crystal diode or a transistor. The glass part may, for example, be a glass cover arranged on another part of the envelope which may likewise consist of glass but may alternatively be made of metal.

It is well known to arrange such leads to be comparatively rigid and to weld thinner leads to their ends required to be arranged internally of the envelope in a manner similar to that used in many electric discharge tubes. However, this construction requires a comparatively large amount of space. It is desirable for these leads internally of the envelope to be thin in order to transmit a minimum amount of heat to the semi-conductive body in the process of arranging the cover onto the other part of the envelope, which is usually effected by heat-sealing, and also in order to arrange these leads to be very flexible in order to prevent an excessive mechanical load from being imposed on the soldering joints to the semi-conductive body.

It is an object of the invention to provide a construction which occupies very little space and can be manufactured in a simple manner.

According to the invention the leads consist of metal wire from which the coating has been removed internally of the envelope and the core of which extends continuously.

The term coating as used herein is to be understood to mean the surface part of the wire. This part may consist of a metal difierent from that of the core, for example of copper. The use of such wire for manufacturing through-glass lead-ins is well-known. Preferably at least the core consists of a metal of low thermal conductivity, for example of a nickel-iron alloy.

If required, the entire wire may consist of this alloy. Such an alloy has the advantage that the heat required for sealing the cover to the other part of the envelope is only transmitted to the semi-conductive body to a slight extent.

The coating portion or the coating can be removed in a simple manner by etching.

It should be noted that the term glass as used herein is to be understood also to mean ceramic material.

The invention will now be explained with reference to the accompanying drawing, in which an embodiment thereof is shown by way of example, and the single figure of which is a cross-sectional view of a transistor on an enlarged scale.

The transistor comprises a semi-conductive body 1 consisting, for example, of germanium and having two electrodes 2 and 3 fused to it. To these parts thin conductive supply leads 4 are secured by soldering which at their upper ends terminate in thicker leads 5 which are sealed in a glass cover 6. This cover is arranged in a flanged rim 7 of a metal can 8 closed at the bottom and is sealed to this rim by means of glaze. The bottom part of the can contains a filler 9 enclosing the semi-conductive body and acting to improve the heat dissipation. As a filler use may be made of the so-called silicone grease.

The assembly consisting of the leads 4 and 5 and the cover 6 is made as follows. Three wires comprising a core which consists of an alloy containing 42% of nickel and 58% of iron and is 0.3 mm. in diameter and a copper coating 0.05 mm. in diameter are sealed into a glass disc 6 moulded into the shape shown. Subsequently the lower ends of the wires are dipped in an etching bath dissolving the copper, for example in dilute nitric acid.

The fact that the welds hitherto used in such constructions to join two different kinds of wire are eliminated enables the length to be shorter and the wires to be sealed into the glass in closer proximity to each other. In addition, the likelihood of stresses in the glass is reduced, While finally the likelihood of poor welding joints is entirely eliminated.

It is also possible to manufacture the leads 4 and 5 from homogeneous material, for example entirely from a nickel-iron alloy, and to arrange the lower ends to be thinner, which again can be elfected in a simple manner by etching. Finally, use may also be made of wire the coating and the core of which consist of difierent metals, not only the coating but also part of the core being re moved at the inner end.

In all these cases the advantage is obtained that the heat produced when sealing the cover to the can is transmitted to the semi-conductive body to a slight extent only.

What is claimed is:

1. A semi-conductor device comprising an envelope including a portion of glass, a semi-conductive body within said envelope, and a plurality of conductive members heat sealed through and within said glass portion of the envelope and coupled to said semi-conductive body, said conductive members each comprising a single metal wire having a first outer portion of larger diameter sealed in the glass portion and extending externally of the envelope but spaced from the semi-conductive body and a second continuous core portion of smaller diameter within the envelope extending to the semi-conductive body and extending continuously within the first outer portion externally of the envelope, thereby to reduce the transfer of heat from the envelope to the semi-conductive body.

2. A semi-conductor device as set forth in claim 1 wherein at least the second portion of the metal wire consists of a nickel-iron alloy.

3. A semi-conductor device comprising an envelope including a portion of glass, a semi-conductive body within said envelope, and a plurality of conductive members heat-sealed through and within said glass portion of the envelope and coupled to said semi-conductive body, said conductive members each comprising a single metal wire having a first outer portion of larger diameter sealed in the glass portion and extending externally of the envelope but spaced from the semi-conductive body and a single continuous core portion of smaller diameter within the envelope extending to the semi-conductive body and extending continuously within the first outer portion externally of the envelope, thereby to reduce the transfer of heat from the envelope to the semi-conductive body, said continuous core being constituted of a nickel-iron alloy, and said first portion including a copper coating on the nickel-iron core.

References Cited in the file of this patent UNITED STATES PATENTS

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