JPS586793A - Brazing filter metal - Google Patents

Abstract

PURPOSE:To obtain a brazing filler metal of <=600 deg.C m.p. by using silver and >=1 kind selected from the group consisting of Sn, Sb, In, Bi as essential components. CONSTITUTION:The melt of an alloy consisting of silver contained with >=1 kind selected from the group of Sn, Sb, In, Bi is subjected to, for example, ultra- quick cooling, whereby the alloy of extremely uniform structure such as an amorphous state is obtained. The brazing filler metal of <=600 deg.C m.p. is obtained by such method. All the above-described elements except silver have low affinity to oxygen and do not require need for the use of any flux. This brazing filler metal is particularly suited for brazing of copper-carbon fiber composite materials.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brazing filler metal, and particularly to a brazing filler metal containing silver.

Brazing filler metals are generally classified into hard solder and soft solder depending on their melting points. Soft solder has a melting point lower than 400C, and hard solder has a melting point higher than 600C. Until now, there have been few materials that have a melting point in the intermediate temperature range of 420C to 600C, and none are known other than Zn-At, which is used for At-brazing.

However, since Zn--At has a high affinity for oxygen, it is necessary to use a solvent during brazing to prevent the melted brazing material from coming into contact with oxygen.

The use of a welding material not only complicates the soldering work, but also poses problems such as the gas generated by the molten solvent being toxic and corroding the soldering material.

Silver has low oxygen efficiency, so silver thread brazing fillers do not require a solvent or only require a small amount, and brazing can be performed in hydrogen or vacuum. The only known materials are those with melting points of 6,000 or higher. This is an alloy of silver (melting point 961C) and other low melting point metals.
Therefore, the liquidus line and solidus line are separated, and 600C! J.
This is because it does not have a lower melting point.

The purpose of the present invention is to solve the problems of the prior art,
To provide a brazing filler metal that has a low melting point and does not require a solvent.

The present invention aims to achieve this object by using a brazing filler metal whose main component is silver and one or more selected from the group of Sn, Sb, Zn, and Bj and has a melting point of 600C or less.

The alloy structure may be amorphous or extremely fine. By creating such a uniform structure, separation of the liquidus line and solidus line is prevented.

Examples of brazing materials with a uniform structure include molten metal quenching materials, fine wire materials, and fine grain materials, among which molten metal quenching materials are particularly preferred. This is because it is ultra-rapidly cooled from a molten state, resulting in an extremely uniform structure such as an amorphous state.

In this molten metal quenching material, a thin plate-like material with a thickness of 0.2 m or less is particularly preferable because the smaller the thickness, the faster the cooling rate and the more uniform the structure.

In the present invention, the silver content is preferably 40 to QQ
Wt ratio, particularly preferably 45 to 55 ratio. In this range, the melting point is constant at 430 to 550C, and a brazing filler metal with stable properties can be obtained.

In the present invention, components other than the silver plate include Sn,
It contains one or more selected from the group consisting of 13i Sb. All of these elements have a low affinity for oxygen, so there is no need to use a solvent.

The brazing material of the present invention is particularly suitable for brazing copper-carbon fiber composite materials.

Copper-carbon fiber composite material (hereinafter referred to as CU-C) is currently under development and is expected to be put to practical use in the near future. One example of its promising use is as a conductive material for semiconductors with a low coefficient of expansion and high thermal conductivity. Since CU-C is a composite of copper and charcoal, materials with significantly different coefficients of thermal expansion, when exposed to high temperatures, it tends to peel off and break at the interface between copper and carbon. FIG. 1 shows the measurement results regarding the relationship between heating temperature and thermal breakdown incidence for CU-C composite materials. (The heating rate is 50 rpm and the holding time is 10 min.) As can be seen from Figure 1, when performing brazing, especially hard soldering, when conventional hard soldering materials are used, the working temperature is high. There is a drawback that if the temperature exceeds 600C or more, CLI-C will be thermally destroyed due to the stress difference due to thermal strain. Furthermore, in the case of soft soldering, CU-C cannot be used in a high temperature range because the melting point of the solder is low. According to the brazing material of the present invention, it is possible to solder Cu--C materials without thermally destroying them, and moreover, it can be used at higher temperatures than conventional soft soldering materials. Further, there is no need to use flux during soldering.

In addition, in the present invention, it is preferable that impurities fall within the following range.

Pb and Ccl are preferably 2% or less since they reduce wettability and tend to cause segregation. - AueP a and pt are preferably 2% or less since the melting point becomes high.

Since ht, zr, and si form an oxide film and inhibit the flow of wax, it is preferable that their content is 0.5% or less.

The following will be explained based on examples.

Example 1 Alloys having the compositions shown in Table 1 were quenched by the molten metal quenching method shown in FIG.
.

0.4. It was formed into a thin long ribbon having a width of 0.8 m and a width of 15 mI+.

In FIG. 2, a crucible 1 and a brazing alloy 2 are heated by an induction heating coil 3, become molten, and are ejected onto a copper roll 4 to form a fine wire 5.

In the figure, 7 is a nozzle that sprays the inert gas 6.

The melting point of the brazing filler metal thus produced is 10C/'-
Table 2 shows the results measured at heating rates ranging from ~100 C/m. Among the data in Table 2, the liquidus temperature and solidus temperature of &1 are shown as a graph in FIG.

Whistle 1 Back upper row: Liquidus temperature Lower row: Solidus temperature From Table 2, it is recognized that the brazing filler metal of the present invention has a melting point of 430 to 550C. Furthermore, from Table 2 and Figure 3, it is recognized that when the thickness exceeds 0.4 mm, the melting temperature range becomes wider. That is, when the thickness exceeds 0.4 square centimeters, the effect of quenching the molten metal decreases, and the structure of the thin plate-shaped brazing filler metal becomes more segregated and less uniform. When this happens, fluidity deteriorates during soldering, which tends to cause void defects and unfilled soldering gaps.

Table 3 shows the results of soldering a structure shown in FIG. 4 using an alloy having the composition shown in Table 1.

In addition, FIG. 4A is a sectional view showing the state before soldering,
11 is a CU-C based composite material, 12 is a nickel plating layer, 13 is a brazing material, 14 is a Cu plate, 15 is an Ag plating layer,
It is. FIG. 4B is a sectional view showing a state in which the solder fluid is drained, and 116 is the solder material after soldering. From Table 3, it is recognized that the wax property decreases when the plate thickness is 0.4 m or more.

○Defect rate 3% or less 64-10. %X10% or more, the brazing material of the present invention has a melting point lower than that of conventional hard solder, does not require a solvent, and has excellent brazing properties. In particular, highly reliable brazing can be performed without thermally destroying the CU-C composite material.

[Brief explanation of drawings]

Figure 1 is a graph showing the heat resistance temperature of CU-C, Figure 2 is an explanatory diagram showing an example of a molten metal quenching method, Figure 3 is a graph showing measurement data of the melting point of Ag-8n hard solder, and Figure 4 is a graph showing the melting point data of Ag-8n hard solder. FIG. 2 is a cross-sectional view of a structure used in a brazing experiment. l...rutsu, 4...roll, 11...CU-C
system composite material.
- Kamiyari Ire Shiba Brain Shi Degree ('cn Figure 2)

Claims (1)

[Scope of Claims] 1. The main component is silver and one or more selected from the group consisting of Sn, Sb, zn, and 13i;
A brazing filler metal characterized by having a melting point of C or lower. 2. The brazing material according to claim 1, wherein the content of silver is 40 to 60% by weight. 3. The brazing filler metal according to claim 1, wherein the content of silver is 45 to 55% by weight. 4. The brazing material according to claim 1, wherein the brazing material is a molten metal quenching material. 5. The brazing material according to claim 4, which is in the form of a thin plate with a thickness of 0.2 mm or less.