JPH1177367A - Solder composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the Pb-free solder which is heat resistant, and excellent in strength and workability by containing Sn, Cu and Ge. SOLUTION: When Ge is added to the Sn-Cu solder, Ge is diffused in the solder to refine the structure, and the strength of the solder is increased. In a molten condition, a thin and stable oxide film of Ge is formed on the solder surface to suppress oxidation of the solder. Preferably, Cu is contained by 0.1-9 wt.% and Ge is contained by 0.001-0.5 wt.% based on 100 wt.% solder composition. More preferably, Cu is contained by 0.7-3 wt.% and Ge is contained by 0.01-0.1 wt.% based on 100 wt.% solder composition. At least one kind of Ag, Sb, Zn, Bi and In may be added to the solder composition as the sub- composition. The solder composition can be fed in any shape including rod-shape and wire-shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder composition used for soldering electronic parts.

[0002]

2. Description of the Related Art Conventionally, when joining electronic parts, Sn-
Pb-based solder is used. Above all, Pb-rich high melting point solders such as Sn-70Pb and Sn-85Pb have been used as the solder for stripping the coated enamel wire which is required to be operated at a high temperature due to the problem of erosion of the Cu wire and solder heat resistance.

[0003] In recent years, Sn-Ag-based and Sn-Ag-Bi-based solders containing no Pb have been developed in consideration of the global environment.

However, the above-mentioned Sn-Ag system and Sn-Ag
In the case of -Bi solder, the melting point of the solder is low, and the solder heat resistance is insufficient for electronic components, and there is a problem that the Cu wire is eroded, particularly for coating enamel wire peeling.
A material having a high melting point and excellent solder heat resistance was required. Therefore, as a result of various studies, Sn-C
A u-based solder has been used as having excellent characteristics.

[0005]

However, Sn-
The problem of the Cu-based solder is that the solder dross amount increases, greatly affecting workability and cost, and when the Cu amount is excessive, the strength decreases due to the influence of the Sn-Cu intermetallic compound. was there.

Therefore, an object of the present invention is to provide a conventional Sn-P
An object of the present invention is to provide a solder composition which is excellent in strength and workability while maintaining the solder heat resistance of a b-type high melting point solder.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has completed a solder composition.

[0008] The solder composition of the first invention of the present application comprises:
It is characterized by containing Cu and Ge.

When Ge is added to Sn—Cu based solder, G
e is dispersed in the solder and the structure becomes finer, so that the strength of the solder increases. In addition, at the time of melting, Ge forms a thin and stable oxide film on the surface of the solder, so that oxidation of the solder can be suppressed.

[0010] In the solder composition according to the second aspect of the present invention, Cu is included in 0.1% of the solder composition of 100 wt%.
It is preferably 1 to 9 wt%.

In the solder composition according to the third aspect of the present invention, Ge is contained in 0.1% of the solder composition of 100 wt%.
It is preferably 001 to 0.5 wt%.

Further, in the solder composition according to the fourth aspect of the present invention, Cu is contained in 0.1% of the solder composition of 100% by weight.
It is selected from 7 to 3 wt%.

In the solder composition according to the fifth aspect of the present invention, Ge is contained in 0.1% of the solder composition of 100 wt%.
It is selected from 01 to 0.1 wt%.

In the solder composition according to the sixth aspect of the present invention, at least one of Ag, Sb, Zn, Bi, and In may be added as a sub-component.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the solder composition of the present invention will be described.

Table 1 shows the solder compositions of Sample Nos. 1 to 23. The overall evaluations in Table 1 are as follows: ：: very good, 、: good, Δ: practically acceptable,
X: There is a problem in practical use.

[0017]

[Table 1]

A bar-shaped solder was prepared so as to obtain the solder composition shown in Table 1, and the Cu wire erosion time, dross amount, and tensile strength were measured.

With regard to the Cu wire erosion time, the Cu wire was immersed in a solder bath at 480 ° C. while holding one side of the U-shaped Cu wire, and the time until the Cu wire disappeared and fell was determined as the Cu wire erosion time. And The evaluations in Table 1 show that ○: took a sufficiently long time, Δ: took a time that had no practical problem, and x: had a practical problem.

Regarding the dross amount, the solder was melted at 480 ° C., and a rotary squeegee was applied to the solder surface, and the dross amount was 3 rpm at 20 rpm.
The amount of dross generated when stirring for 0 minutes was measured.

Regarding the tensile strength, the Cu plate and the Cu
The tensile strength of the wire joined by solder was used.

As shown in Table 1, the amount of Cu was 0.1 wt%.
If the ratio is less than the above, Cu line erosion is likely to occur, which is not preferable. On the other hand, if the Cu content exceeds 9 wt%, the tensile strength is undesirably reduced. More preferably,
The amount of Cu is in the range of 0.1 to 9 wt%, and more preferably 0.7 to 3 wt%.

When the amount of Ge is less than 0.001 wt%, the effect on the dross amount is not seen, and
If it exceeds, the effect will be saturated. Ge is expensive, and as the amount of Ge used increases, the cost increases. Therefore, the amount of Ge is 0.001 to 0.5 wt.
% Is preferable, and 0.01 to 0.1 wt% is more preferable.
Is preferable.

Further, from Table 1, in addition to Sn, Cu and Ge,
It can be seen that the same effect is obtained even when at least one of Ag, Sb, Zn, Bi, and In is added.

The solder composition can be supplied in any shape, such as a bar, paste, or wire, and the shape is not limited.

Here, in the present invention, a three-component system of Sn, Cu and Ge is shown as the solder composition, but it may contain an unavoidable impurity. The unavoidable impurities include elements that are mixed in when manufacturing the solder or elements originally contained, for example, Pb, Bi, and Na.

[0027]

As described above, according to the present invention, the workability is equivalent to that of the conventional Sn-Pb high melting point solder, and
A solder composition capable of free soldering can be obtained.

Claims (6)

[Claims] 1. A solder composition comprising Sn, Cu, and Ge. 2. The method according to claim 1, wherein the Cu is 100 wt% of the solder composition.
The solder composition according to claim 1, wherein the content of the solder composition is 0.1 to 9 wt%. 3. The method according to claim 1, wherein the Ge is 100 wt% of the solder composition.
%. The solder composition according to claim 1, wherein the content is 0.001 to 0.5 wt%. 4. The method according to claim 1, wherein the Cu comprises 100 wt% of the solder composition.
The solder composition according to any one of claims 1 to 3, wherein the content of the solder composition is 0.7 to 3 wt%. 5. The solder according to claim 1, wherein the Ge is 100 wt.
The solder composition according to any one of claims 1 to 4, wherein the content is 0.01 to 0.1 wt%. 6. Ag, Sb, Zn, B as subcomponents
The solder composition according to claim 1, wherein at least one of i and In is added.