JPS611468A - Production of silver brazed structural body - Google Patents

Abstract

PURPOSE:To prevent the exfoliation of an Ni plating layer by subjecting plural members provided with the parts where metal and glass are sealed to silver brazing in a slightly oxidizing atmosphere and forming successively a silver plating layer and Ni plating layer to the silver brazed structural body. CONSTITUTION:Transparent glass 5 is sealed into the large-diameter through- hole 2 of an outside metallic ring 1 and lead wires 7 are hermetically and isolatedly sealed via glass 6 into small-diameter through-holes 3. After such sealed body is pickled, the glass sealed body, screw members 8, a cylindrical member 9 and silver solder 10 are assembled in prescribed relative positions and are heated to about 800 deg.C in the slightly oxidizing atmosphere, by which these members are silver-brazed. The silver-brazed structural body is pickled and is then dipped in a cyan plating bath, by which a copper plating layer 11 is formed to about 2-4mu thickness. An electroless Ni placting layer 12 is further formed on the layer 11 to abou 4-6mu thickness. Since the layer 12 has the good adhesiveness to the layer 11, the exfoliation thereof is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for manufacturing a silver brazed structure, and is particularly used for manufacturing containers such as semiconductor devices, crystal oscillators, and electronic water meters.

BACKGROUND OF THE INVENTION Silver brazing is widely used to bond two members together.

3(2) is a plan view of an electronic water meter container disclosed in, for example, Japanese Unexamined Patent Publication No. 56-120080, and FIG. 4 is a sectional view taken along the line ■-■ in FIG. show. In the figure, 1 is a metal external term consisting of iron, low carbon steel, Kobar) v (Iron-2, Kel-Kova/l/ ) alloy), and there is one large-diameter through hole 2 and three small-diameter through holes. through holes 3 and recesses 4 on both sides of these small diameter through holes 3. A transparent glass 5 is hermetically sealed in the through hole 2. A lead wire 7 is hermetically sealed in each through hole 3 with a glass 6 interposed therebetween. Also,
In each of the recesses 4, a screw member 8 made of brass or the like and having a thread carved on its inner surface is soldered with silver. Reference numeral 9 denotes a cylindrical member made of copper, which is soldered with silver to the lower surface of the metal outer ring 1.

The sealing between the metal outer ring 1 and the transparent glass 5 and the glass 6 and the sealing between the glass 6 and the lead wires 7 are performed through oxidation of the surfaces of the metal outer ring 1 and the lead wires 7. This is because the transparent glass 5 and the glass 6 themselves are composed of metal oxides, which easily stagnate with the oxide film of the metal outer ring 1 and the lead wire 7, thereby achieving excellent hermetic sealing.

Problems to be Solved by the Invention By the way, general silver brazing of two members is carried out in a reducing atmosphere, but silver brazing of the metal outer ring 1 and the screw member 8 or the cylindrical member 9 is difficult. If this is carried out in the same atmosphere as before, the following problems may arise.

(1) When silver brazing is carried out in a reducing atmosphere, the oxide film on the surface of the metal outer ring 1 and the lead wire 7 is reduced and disappears, which tends to cause airtightness deterioration. In other words, the oxide film on the metal outer ring 1, the lead wire 7, etc. contributes to excellent sealing with the glass as described above, but if the crow eats away all the oxide film, the glass and the metal base will be damaged. Since they come into direct contact and the airtightness deteriorates, it is known that good sealing results can be obtained if the sealing is performed under conditions where the oxide film remains. However, when silver brazing is performed in a reducing atmosphere, the oxide film left during sealing is reduced and disappears from the edge of the sealing interface between the metal and glass, resulting in microscopic gaps between the metal and glass. Gaps are formed, resulting in deterioration of airtightness and reduction in sealing strength.

(2) On the other hand, when silver brazing is performed in a neutral atmosphere, the copper in the silver solder is oxidized due to the oxygen permeation and solubility of the molten silver solder during brazing due to the air brought in by the brazing jig. Not just being treated.

The copper base of the screw member 8 and the cylindrical member 9 is also oxidized. Although the oxide film on the surface of the screw member 8 and the cylindrical member 9 can be easily removed by pickling or the like before finishing plating, the copper entrainment film in the root wax cannot be removed. For this reason, when a finish is applied after pickling, the nickel plating layer peels off because nickel has poor adhesion to both the roots in the silver solder and the oxidized copper.

Means for Solving the Problems The present invention includes a step of silver brazing a plurality of members, at least one of which has a metal-to-glass sealing portion, in a slightly oxidizing atmosphere, and a method for applying silver brazing to the above-mentioned silver brazing structure. This method is characterized by including a step of forming a copper plating layer and a step of forming a nickel plating layer on the copper plating layer.

Effect According to the above method, since silver brazing is carried out in a slightly oxidizing atmosphere, the oxide film at the sealing interface between metal and glass will not be reduced and disappear, thereby preventing airtightness deterioration or mechanical sealing. There is no decrease in strength. Even if the copper in the silver solder is oxidized in the atmosphere during silver brazing, the copper plating layer has good adhesion to the silver in the silver solder, so the bond between the silver solder and the copper plating layer is good. Adhesion is good. Furthermore, it has good adhesion to the copper plating layer and the second layer. As a result, it is possible to prevent the peeling of the silver solder layer at the silver soldered portion.

Embodiment FIG. 1 shows a process block diagram of a method according to an embodiment of the present invention. FIG. 2 shows an enlarged sectional view of a main part when the present invention is applied to the electronic water meter container shown in FIGS. 3 and 4. In FIG. 2, the same parts as in FIG. 4 are given the same reference numerals, and their explanations will be omitted.

First, the transparent glass 5 is sealed in the through hole 2 of the metal outer ring 1, and the lead wire 7 is sealed in an airtight and insulated manner through the glass 6 in each through hole 3 (FIG. 1, fL). After pickling the glass sealing body, using a brazing jig (not shown) made of graphite, the glass sealing body, which is the first member, and the glass sealing body, which is the second member, are assembled. The screw member 8, the cylindrical member 9 that is the third member, and the silver solder 10 are assembled in a predetermined relationship position, and heated at approximately 80θ in a slightly oxidizing atmosphere that includes the static electricity introduced by the brazing jig. Heat to ℃ and roast with silver. At this time, unlike conventional silver brazing in a reducing atmosphere, the oxide film on the glass-sealed portion of the metal outer ring 1 and the lead wire 7 is not reduced and disappears. (Figure 1b
).

Next, after pickling this silver brazed structure, a copper plating layer 11 having a thickness of 2 to 4 μm is formed using a cyan-based plating bath. Even if the copper in the silver solder 10 is oxidized, this copper plating layer 11 has good adhesion to the silver in the silver solder 1°, so it firmly adheres to the silver in the silver solder 1o. This is presumably because the presence of CN- in the copper plating layer 11 is largely related to the activity of silver (FIG. 1C).

Subsequently, an electroless Nickel plating layer 12 is formed on the copper plating layer 11 to a thickness of 4 to 6 μm. Since this electroless nickel plating layer 12 has good adhesion to the copper plating layer 11, the adhesion between the two is also sufficient (FIG. 1d).

The following table shows the relationship between the atmosphere during silver brazing, plating specifications, and the rate of plating peeling.

It should be noted that it is difficult in mass production to completely eliminate the space in the brazing jig as shown in C, and when a reducing atmosphere is used as shown in D, the plating layer does not peel off even with the conventional method.
As mentioned above, this method cannot be used because it causes deterioration of airtightness and decrease in sealing strength due to reduction of oxidized particles.

Although the above embodiment describes a container for an electronic water meter, it can also be implemented in a container for a semiconductor device or a crystal oscillator.

Effects of the Investigation As described above, in the present invention, the copper plating layer is formed on the silver brazing part and then the Ni-Kerume-tsuki layer is formed, so that 2. Peeling of the KEL-plated layer can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a process block diagram for explaining one embodiment of the method of the present invention, and the second is an enlarged sectional view of the main parts when the present invention is applied to a container for an electronic water meter. FIG. 3 is a plan view of an electronic water meter container as an example of a silver brazed structure, and FIG. 4 is a sectional view taken along line IV--IV in FIG. 3. 1... Metal outer ring (first member), 5...
・Transparent glass, 6...Glass, 7...Lead wire, 8...Screw member (second member), 9...
Cylindrical member (third part), 10 - silver solder, 11... copper plating layer, 12... nickel plating layer. Figure 1

Claims (1)

[Claims] A step of silver brazing a plurality of members, at least one of which has a sealed portion of metal and glass, in a slightly oxidizing atmosphere, and forming a copper plating layer on the silver brazing structure. and forming a nickel plating layer on the copper plating layer.