JPS5835365B2 - Glass terminal manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a glass terminal, and in particular, proposes a method for manufacturing an airtight glass terminal such as a stem used in a semiconductor device or the like.

In general, as stems for semiconductor devices, conventionally, an iron-nickel alloy lead wire is insulated and held in an iron outer ring with soft glass, and the glass is tightened to maintain airtightness due to the difference in thermal expansion coefficient between iron and glass. There are so-called compression type stems, or so-called matt type stems, which have a Kovar (iron-nickel-cobalt alloy) lumber ring and Nicobar lead wire insulated with hard glass, and maintain airtightness with a Kovar oxide layer. It is used.

Here, compression type stems have an outer ring made of iron, so they have higher thermal conductivity and excellent heat dissipation than matted type stems, and they are compatible with semiconductors that handle larger amounts of power than matted type stems. element can be accommodated.

The compression type stem has the disadvantage that it is subjected to thermal shock during heat treatment when a semiconductor element is fixedly housed therein, resulting in a decrease in airtightness and breakage.

Therefore, as a method for manufacturing a compression type stem having a structure that does not cause a decrease in airtightness, for example, as disclosed in Japanese Patent Publication No. 52-30353, the surface of the iron outer ring is plated with nickel. After applying, heat treatment is performed in a reducing atmosphere to add iron to the surface.
Form a nickel alloy layer, then heat-treat in an oxidizing atmosphere to convert the surface of the iron-nickel alloy layer into an oxide, then insert glass and lead wire into the ring, and then,
It has been proposed that the lead wire, glass, and iron outer ring be closely fixed together by melting glass, but compression type stems manufactured by this manufacturing method have problems such as insulation between the lead wire and the outer ring. It has problems such as low resistance.

This is because nickel oxide is left in the form of bubbles mixed into the glass that fixes the lead wire and the outer ring.

That is, due to the presence of the cellular nickel oxide, the molten glass tube bulges, causing unnecessary protrusion of the glass on the upper or lower surface of the iron outer ring.

However, due to the presence of the cellular nickel oxide, the effective contact area between the lead wire and the glass as well as the iron outer ring and the glass is small, resulting in a decrease in the bonding strength between them.

Further, the presence of the foamed nickel oxide causes moisture to be impregnated into the foam, resulting in a decrease in insulation resistance between the iron outer ring and the lead wire.

For example, in the compression type stem,
The resistance between the iron outer ring and V-t"i is 106 to 10
It is as low as 12 (Ω), and the variation in its value is also small.

The present invention aims to provide a manufacturing method that can solve the various problems of conventional glass terminals, particularly compression type stems, without reducing their airtightness.

Therefore, according to the present invention, at least cobalt plating is applied to a metal outer ring made of iron or iron as a main component, and then the cobalt-plated metal outer ring is placed in a reducing atmosphere. Heat-treating to form at least an iron-cobalt alloy layer on the surface of the metal outer ring, and then heat-treating the metal outer ring in an oxidizing atmosphere to form an oxide film on the surface of the metal outer ring. glass and a lead wire are then inserted into the metal outer ring, and then the glass is melted to form a lead wire,
A method of manufacturing a glass terminal is provided, which is characterized by closely fixing glass and metal outer rings.

That is, according to the present invention, the basic idea is to apply at least cobalt plating to the outer ring made of iron or a metal whose main component is iron.

The presence of the cobalt layer can significantly suppress the formation of nickel oxides that are formed in layers below or above the cobalt layer, or deposited together with the cobalt layer, thereby preventing the formation of nickel oxides between the lead green and the outer ring. It is possible to prevent a decrease in dielectric strength voltage, etc.

This takes advantage of the fact that cobalt has a greater affinity with oxygen than that between nickel and oxygen.

Next, the present invention will be explained in detail with reference to the drawings.

1 to 4 are cross-sectional views of a metal outer ring showing the manufacturing process of a glass terminal according to the manufacturing method of the present invention.

According to the present invention, as shown in FIG.
A nickel plating layer 3 with a thickness of about 1.0 (μm) is formed, and a nickel plating layer 3 with a thickness of 0.5 to 1.0 [μm] is further formed on the surface of the nickel plating layer 3.
m, )/) Cobalt plating layer 4 is formed.

Next, the iron outer ring 2 was heated for 100 minutes in a hydrogen atmosphere.
A heat treatment is performed at 0° C. for about 60 minutes to form an iron-nickel-cobalt alloy layer 5 with a thickness of about 2 to 3 μm on the surface of the iron outer layer 2.

This state is shown in FIG.

Next, the iron outside@2 was heated to 700 [°C] in air.
Heat treatment is performed for about 20 (minutes) to form an oxide film 6 with a thickness of about 2 [μm] on the surface of the iron outer ring 2.

This state is shown in FIG. Next, the lead wire sacrificial mounting of the iron outer section 2 was performed by inserting the glass tube 7 into the hole 1, and further inserting the lead wire 8 made of iron-nickel into the glass tube γ, and then heating it at 1000C in a nitrogen atmosphere. By performing a heat treatment for about 30 minutes to melt the glass tube 7 and further cooling it, the lead wire 8 of the iron outer shell 2 is fixed into the hole 1.

This state is shown in FIG.

As described above, according to the manufacturing method of the present invention, a cobalt layer is formed together with a nickel layer on the surface of the iron outer ring.

Therefore, when the iron-nickel-cobalt alloy layer is oxidized, the nickel oxide is The generation of substances is largely prevented.

For this reason, when attaching the iron outer ring to the hole, when the glass tube and lead wire are inserted into the hole and the glass tube is heated and welded, nickel oxide bubbles are generated inside the glass part. , contamination is significantly reduced.

Therefore, blistering of the glass material due to the presence of the nickel oxide bubbles does not occur, and the amount of the glass material constituting the glass tube can be kept constant.

Since there are no bubbles in the nickel oxide in the casing, there is a substantial contact area between the lead wire and the glass, as well as the iron outer ring and the glass, and there is no reduction in adhesive strength between them.

Furthermore, since there are no bubbles in the nickel oxide, the insulation resistance between the iron outer shell and the main frame does not decrease.

In the above examples, insulation resistance values as high as 1010 to 1013 (Ω) and with relatively little variation were obtained.

This value fully satisfies the value defined from the characteristics of semiconductor devices.

It should be noted that the present invention is not limited to the above embodiments, and the same treatment can be applied to an iron outer ring coated only with cobalt plating or an iron outer ring coated with nickel-cobalt alloy plating. can.

Therefore, the conditions for plating treatment, heat treatment, etc. are not limited to those in the above embodiments.

Overall, according to the present invention, a compression type stem with improved airtightness and insulation properties after thermal shock can be manufactured with a high manufacturing yield.

[Brief explanation of drawings]

1 to 4 are cross-sectional views for explaining the manufacturing process of a glass terminal according to the present invention. In Figures 1 to 4, 1... Lead wire mounting hole, 2... Steel outer ring, 3... Nickel plating layer, 4...・Cobalt plating layer, 5・
...Iron-two/yru~cobalt alloy layer, 6...
...Oxide film, 7...Glass, 8...
·Lead.

Claims (1)

[Claims] 1 Iron! At least cobalt plating is applied to a metal outer ring whose main component is iron or iron, and then the cobalt-plated metal outer ring is heat-treated in a reducing atmosphere to reduce the surface portion of the metal outer ring. At least an iron-cobalt alloy layer is formed on the metal outer ring, and then the metal outer ring is heat-treated in an oxidizing atmosphere to form an oxide on the surface of the metal outer ring, and then glass is injected into the metal outer ring. and insert the lead wire, and then,
A method for manufacturing a glass terminal, which comprises melting the glass and tightly fixing the lead wire, the glass, and the metal outer ring.