JPS6041866B2 - Manufacturing method for airtight terminals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hermetic terminal, and more particularly to an improvement in a method for manufacturing a stem for a can-sealed semiconductor device.

As stems for can-sealed semiconductor devices such as power transistors, those for relatively low power use have the entire stem board made of iron, but for those for medium or higher power use, a copper heat sink is integrally fixed to a steel flange. It has a structured structure. FIG. 1 shows a plan view of an example of such a system, and FIG. 2 shows a cross-sectional view taken along line 1--2 in FIG. In the figure, reference numeral 1 denotes an iron flange, which is approximately diamond-shaped and has a heat sink fitting hole 2 in its center, and 2 near the center.
It has lead wire sealing holes 3, 3, and further has mounting holes 4, 4 at both ends in the longitudinal direction for attaching to a chassis or the like. 5 is a copper heat sink that is fitted into the heat sink fitting hole 2 and brazed; 6 is an iron-nickel alloy that is sealed to the lead wire sealing holes 3 through glass 7; This is the lead wire.

The above-mentioned stem is manufactured, for example, as follows.

First, the heat sink 5 is fitted into the heat sink fitting hole 2 of the flange 1 which is plated with copper or nickel,
After temporarily fixing it to the flange 1 by carving, a cylindrical glass tablet is fitted into the lead wire sealing holes 3, 3, and the lead wires 6, 6 are inserted into the center hole of this glass tablet. The glass tablet is heated to about 1000° C. to melt it, and the lead wires 6, 6 are sealed with glass. next,
Silver solder is placed along the circumferential surface of the heat sink 5, and approximately 85
The heat sink 5 is hermetically soldered to the flange 1 by heating to 0° C. to melt the silver solder. Finally, after activating the entire surface, finish plating such as electrolytic nickel plating is applied.
However, the above method requires two heating steps: glass sealing of the lead wires 6, 6 and silver brazing of the heat sink 5, which is complicated and causes a rise in cost.

Therefore, chemical nickel plating is formed on the side surface of the heat sink 5 in advance, and the heat sink 5 is temporarily fixed by fitting into the heat sink fitting hole 2 of the flange 1, and the lead wire sealing holes 3, 3 are temporarily fixed. Insert the glass tablet into the glass tablet, insert the lead wires 6, 6 into the glass tablet, heat the whole to about 10,000C, melt the glass tablet and seal the lead wires 6, 6 to the glass, and at the same time, heat the glass tablet at the glass sealing temperature. Heat sink 5 is attached to flange 1 by melting the chemical nickel plating on the side of heat sink 5.
A method was proposed in which the material was brazed and then finished with electrolytic nickel plating.

According to the above method, since the heat sink 5 can be brazed at the same time at the glass sealing temperature of the lead wires 6, 6, the cost can be reduced by reducing the number of man-hours.

However, since the flange 1 is pre-plated with copper or nickel, and the final plating is applied after glass sealing and brazing, two plating processes are required, which is still complicated and limits the amount of base paper used. It was hot. Therefore, the following manufacturing method, which is the background of this invention, was proposed.

The manufacturing method will be explained below with reference to FIGS. 3 and 4.
First, as shown in FIG. 3, electrolytic nickel plating 8 is applied to the entire surface of the iron flange 1, electrolytic nickel plating 9 is applied to the entire surface of the copper heat sink 5, and then chemical nickel plating 10 is applied only to the side surfaces. the heat sink 5 is fitted into the heat sink fitting hole 2 of the flange 1,
Temporarily fix it by caulking. In addition, a cylindrical glass tablet 7a is inserted into the lead wire sealing holes 3, 3 of the flange 1.
, 7a, and electrically nickel-plated lead wires 6, 6 are inserted through the glass tablets 7a, 7a.
Then, the whole is heated to about 1000°C to melt the glass tablets 7a, 7a, and seal the lead wires 6, 6 with the glasses 7, 7, and at the same time, melt the chemical nickel plating 10 and braze the heat sink 5 to the flange 1. When attached, a stem as shown in FIG. 4 is obtained. According to the above manufacturing,
Not only can the glass sealing of the lead wires 6, 6 and the brazing of the heat sink 5 be performed at the same time, but the exposed parts of the flange 1, heat sink 5, and lead wires 6, 6 are all coated with electrolytic nickel plating, making it easy to finish. This has the advantage of eliminating the need for plating, further reducing the number of man-hours and reducing costs. However, if the electrolytic nickel plating 9 is applied to the entire surface of the heat sink 5 and then the chemical nickel plating 10 is applied only to the side surfaces, the melting point of the chemical nickel plating 10 is lower than the softening point of the glass tablet 7a, so the glass tablet 7a The chemical nickel plating 10 melts before softening and melting, and the molten chemical nickel plating is used as the electrolytic nickel plating 8 of the flange 1 and heat sink 5.
. Furthermore, the hot water flows to the cap welding area, and when the cap is welded, hot water beads are generated and adhere to the semiconductor elements, causing deterioration of their characteristics.

Therefore, the main object of the present invention is to provide a method for manufacturing a stem that can solve the above-mentioned problems while taking advantage of the advantages of the above-mentioned manufacturing method.

To summarize, this invention applies chemical nickel plating to the brazing portion of at least one of iron-based parts such as flanges and copper-based parts such as heat sinks, and then connects these iron-based parts and copper-based parts in a predetermined relationship. Caulk it into position and temporarily fix it.
Electrolytic nickel plating is applied to the entire surface of this temporary fixing body, this temporary fixing body is assembled together with the lead wire and the glass tablet in a predetermined relationship position, and the whole is heated to melt the glass tablet and the lead wire is made of glass. At the same time as the sealing, the chemical nickel plating is melted and the iron-based parts and the copper-based parts are brazed together. The above-mentioned objects and other objects and features of the present invention will become more apparent from the detailed description of the invention given with reference to the drawings.

First, a case in which the present invention is implemented for manufacturing a stem having the structure shown in FIGS. 1 and 2 will be explained with reference to FIGS. 5 to 8.

First, as shown in FIG. 5, an iron flange 1 and a copper heat sink 5 are manufactured, and at least one of them is coated with chemical nickel with a thickness of about 5 to 15 μm on the part to be brazed, for example, only on the side surface of the heat sink 5. Apply plating 10.
At this time, for example, a plating resist layer is formed on the top and bottom surfaces of a copper plate of a predetermined thickness, and this copper plate is punched out in a circular shape to produce the heat sink 5 whose top and bottom surfaces are covered with the plating resist layer and only the side surfaces are exposed. Alternatively, a method may be adopted in which chemical nickel plating 10 is applied only to the side surfaces exposed by barrel plating or the like, and the plating resist layers on the upper and lower surfaces are removed. Next, as shown in FIG. 6, the heat sink 5 is fitted into the heat sink fitting hole 2 of the flange 1, mechanically caulked to produce a temporary fixed body 11, and this temporary fixed body 11 is activated. After that, electrolytic nickel plating 112 with a thickness of about 2 to 8 μm is applied to the entire surface. Subsequently, as shown in FIG. 7, cylindrical glass tablets 7a, 7a are inserted into the lead wire sealing holes 3, 3 of the flange 1 of the temporary fixing body 11, and the center holes of the glass tablets 7a, 7a are inserted. , thickness 2~ on the entire surface
Lead wires 6, 6 with electrolytic nickel plating of about 8μ
Insert and assemble into position. Finally, when the whole is heated to about 1000° C. in a neutral or weakly reducing atmosphere, the glass tablets 7a, 7a are melted and the lead wires 6, 6 are connected to the glasses 7, 7 as shown in FIG. At the same time, the chemical nickel plating 10 on the side surface of the heat sink 5 is melted and the flange 1 is hermetically sealed.
and the heat sink 5 are integrated by brazing. According to the above manufacturing method, chemical nickel plating 10 is applied to the side surface of the heat sink 5, the heat sink 5 is caulked and temporarily fixed to the flange 1 to produce the temporary fixed body 11, and the entire surface of the temporary fixed body 11 is electrically Since the nickel plating 12 is applied, the plating process is simple and requires only one plating process, compared to the case where the flange 1 and the heat sink 5 are electrolytically nickel plated 8 and 9 separately. Not only that, when the chemical nickel plating 10 melts at the heating temperature during glass sealing, the entire surface has a higher melting point than the chemical nickel plating 10. Because it is covered with electrolytic nickel plating 12, the molten chemical nickel plating 10 does not flow and spread over the top surface of the flange 1 and heat sink 5 as in the past, but instead flows into the glass sealing interface and deteriorates the airtightness. It may flow to the half of the heat sink 5, the part where the conductive element is to be fixed, and deteriorate the adhesion of the semiconductor element, or it may flow to the part of the flange 1, where the cap is to be welded, and the characteristics of the semiconductor element may be deteriorated by hot water droplets during welding of the cap. All the problems you have had will disappear. In the above embodiment, the heat sink fitting hole 2 is formed in the flange 1, and the chemical nickel plating 10 is applied only to the side surface of the heat sink 5.
Although a case has been described in which a recess for fitting the heat sink is formed in the flange, chemical nickel plating may be applied to the side and lower surfaces of the heat sink so that the heat sink is fitted into the recess. FIGS. 9 to 12 show cross-sectional views of each process in the case where the present invention is applied to the manufacture of stems of other configurations.

In this embodiment, as shown in FIG. 9, a large-diameter heat sink fitting hole 14 is formed in the center of the flange 13, and an eyelet 17 is formed in the large-diameter heat sink 15 that is fitted into the heat sink fitting hole 14◆. , 17 are bored, and chemical nickel plating 10 is applied to the side surfaces thereof and the inner surfaces of the eyelet fitting holes 16, 16. Next, as shown in FIG. 10, the heat sink 15 is fitted into the heat sink fitting hole 14 of the flange 13.
Iron eyelets 17 are installed in the eyelet fitting holes 16, 16.
, 17 are fitted and caulked to temporarily fix the three parts 1
8 is manufactured and electrolytic nickel plating 12 is applied to the entire surface. Furthermore, as shown in FIG. 11, the glass tablets 7a, 7a are fitted into the eyelets 17, 17 of the temporary fixing body 18,
Lead wires 6, 6 are inserted into the glass tablets 7a, 7a and assembled at predetermined relative positions. Finally, by heating the whole, the glass tablets 7a, 7a are melted, and the lead wires 6, 6 are sealed with glass, as shown in FIG. The chemical nickel plating 10 on the inner surfaces of the holes 16, 16 is melted and the flange 13, heat sink 15 and eyelets 17, 17 are brazed. In each of the above embodiments, a stem in which an iron flange and a copper heat sink are brazed together has been described. However, in this invention, an iron eyelet is fitted into an eyelet fitting hole of a copper flange and brazed, and the eyelet is It can also be applied to the manufacture of a stem in which a lead wire is sealed in glass and a welding ring for cap welding is brazed to the upper surface of the flange.

Further, the present invention can be applied to the manufacture of airtight terminals other than stems for semiconductor devices.

Furthermore, this invention is applicable not only to brazing iron parts and copper parts, but also to brazing iron parts such as iron alloys whose main component is iron or copper parts such as copper alloys whose main component is copper. It can also be applied to things that are attached.

As described above, the present invention includes a process of applying chemical nickel plating to a portion of at least one of an iron-based part and a copper-based part to be brazed, and a process of caulking these iron-based parts and copper-based parts into predetermined positions. A step of fixing, a step of applying electro-nickel plating to the entire surface of this temporary fixing body, a step of assembling the temporary fixing body together with the lead wire and the glass tablet in a predetermined position, and heating the whole to fix the glass tablet. This process includes melting and sealing the lead wires with glass, and simultaneously melting the chemical nickel plating and brazing the iron-based parts and copper-based parts together. Brazing parts and copper-based parts can be performed simultaneously, and finishing plating is not required, making manufacturing easier and reducing costs.

Furthermore, since electrolytic nickel plating is applied on top of chemical nickel plating, which has a higher melting point than chemical nickel plating, molten chemical nickel plating does not flow and spread over metal parts during glass sealing, eliminating airtightness and appearance defects. can. Particularly in a stem for a semiconductor device, it is possible to prevent the adhesion of the semiconductor element from deteriorating or the characteristics of the semiconductor element from deteriorating due to molten metal beads during cap welding.

[Brief explanation of the drawing]

1 and 2 show an example of a stem for a semiconductor device, with FIG. 1 being a plan view thereof, and FIG. 2 being a sectional view taken along line 1-1 in FIG. Figures 3 and 4 are for explaining the manufacturing method of the stem, which is the background of this invention. Figure 3 is an exploded sectional view before glass sealing, and Figure 4 is a sectional view after glass sealing. It is.
FIGS. 5 to 8 are cross-sectional views of each process for explaining the case where the present invention is applied to the stem shown in FIGS. 1 and 2. FIG. FIGS. 9 to 12 are cross-sectional views of each process for explaining the case where the present invention is applied to a stem having another configuration. 1, 13... Iron parts (flange), 5, 15... Copper parts (heat sink), 6... Lead wire, 7... Glass, 7a ...Glass tablet, 10...
...Chemical nickel plating, 11,18...Temporary fixed body, 12...Electro nickel plating, 17...
Iron parts (eyelets).

Claims (1)

[Claims] 1. In a method for manufacturing an airtight terminal in which a lead wire is sealed to a ferrous component through glass and the ferrous component and the copper component are brazed together, brazing of at least one of the ferrous component and the copper component is planned. A process of applying chemical nickel plating to the parts, a process of caulking and temporarily fixing these iron parts and copper parts in predetermined relationship positions, a process of applying electrolytic nickel plating to the entire surface of this temporary fixing body, and a process of applying electrolytic nickel plating to the entire surface of this temporary fixing body, A step of assembling the fixed body together with the lead wire and the glass tablet in a predetermined relationship position, heating the whole to melt the glass tablet and sealing the lead wire to the glass, and at the same time melting the chemical nickel plating to form an iron-based A method for manufacturing an airtight terminal, comprising the step of integrally brazing a component and a copper component.