JP2001150182A - Gold-tin alloy brazing filler metal having excellent wettability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gold-tin alloy brazing filler metal which has excellent wettability and allows brazing with always high reliability. SOLUTION: This brazing filler metal consists of a composition containing 10 to 30 wt.% Sn and consisting of the balance inevitable impurities and its surface roughness Ra stipulated in JIS B-0601 is in a range from 0.01 to 5 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gold-tin alloy brazing material which has excellent wettability and can always be brazed with high reliability.

[0002]

2. Description of the Related Art In general, as a method of brazing a semiconductor element such as silicon or GaAs to a lead frame plated with gold or a substrate such as metallized ceramics,
A method is known in which a gold-tin alloy brazing material is placed on a substrate and melted, and then a semiconductor element such as silicon or GaAs is placed on the molten brazing material and joined. The gold-tin alloy brazing material used at this time contains Sn: 10 to 30% by weight, and the balance has a composition consisting of Au and unavoidable impurities.
A gold-tin alloy brazing material processed into a narrow band or chip shape is used.

[0003]

However, since the conventional gold-tin alloy brazing material has poor wettability, the molten brazing material has a small area spread over the substrate even when heated and melted, so that silicon, GaAs, etc. A portion where the molten brazing material does not flow around the lower surface of the semiconductor and the periphery thereof, and if such a portion occurs, a portion where the molten brazing material does not adhere to the lower surface of the semiconductor such as silicon or GaAs occurs, and the semiconductor device is reliably brazed. Can not.

[0004]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of research to develop a gold-tin alloy brazing material that can always be reliably brazed using a gold-tin alloy brazing material, (a) the surface roughness of the gold-tin alloy brazing material is This greatly affects the wettability of the material to the substrate, and the smaller the surface roughness of the gold-tin alloy brazing material, the better the wettability of the molten brazing material to the substrate. (B) a gold-tin alloy excellent in wettability capable of performing highly reliable soldering without causing a portion to which the molten brazing material does not adhere to; The surface roughness of the brazing material is such that the surface roughness Ra specified in JIS B0601 is 0.
The research result obtained that it was within the range of 01 to 5 μm.

The present invention has been made on the basis of the above research results, and (1) gold tin having excellent wettability having a surface roughness Ra specified in JIS B0601 in the range of 0.01 to 5 μm. Alloy brazing material.

The gold-tin alloy brazing material of the present invention contains generally known Sn: 10 to 30% by weight, and the balance is Au.
Further, a brazing material having a composition composed of unavoidable impurities can be used. Therefore, the present invention provides (2) Sn: 1
A gold-tin alloy containing 0 to 30% by weight, the balance being Au and unavoidable impurities, and having excellent wettability having a surface roughness Ra defined by JIS B0601 in the range of 0.01 to 5 μm. Brazing material.

[0007] The gold-tin alloy brazing material of the present invention is high-purity Au.
And high-purity Sn as a raw material, 10 to 30% by weight of high-purity Sn is added to high-purity Au, and the mixture is melted in vacuum and cast to produce an ingot.
The thickness is 10 by warm rolling at 170 to 220 ° C.
５０50 μm, and the surface of the band-shaped gold-tin alloy brazing material is polished so that the surface roughness Ra specified in JIS B0601 is 5 μm or less, and then cut in parallel in the length direction to obtain a linear shape. Alternatively, it is formed by shaping into a strip shape and, if necessary, cutting a linear or strip-shaped gold-tin alloy brazing material at right angles in the length direction to form a chip shape.

[0008] Surface roughness R defined by JIS B0601
a: The reason why the gold-tin alloy brazing material of the present invention having a size of 5 μm or less is excellent in wettability is that the surface of the band-shaped gold-tin alloy brazing material is formed by JI.
By smooth polishing so that the surface roughness Ra defined by SB0601 is 5 μm or less, the amount of the oxide film formed on the surface of the gold-tin alloy brazing material is extremely reduced,
It is thought that this was due to a decrease in the factor that hinders the molten metal flowability, but it is not clear.

The surface roughness of the gold-tin alloy brazing material of the present invention is as follows:
The smoother the solder, the greater the wettability of the molten brazing material to the substrate, and therefore the higher the reliability for brazing. However, if the surface roughness Ra of the gold-tin alloy brazing material specified by JIS B0601 exceeds 5 μm, On the other hand, the surface roughness Ra of the gold-tin alloy brazing material specified in JIS B0601 is set to 0.
If the thickness is less than 01 μm, the processing steps become complicated and cost becomes too high, which is not preferable. Accordingly, the surface roughness Ra of the gold-tin alloy brazing material specified in JIS B0601
Was set to 0.01 to 5 μm. JIS for gold-tin alloy brazing material
A more preferable range of the surface roughness Ra defined by B0601 is 0.03 to 1 μm.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION High purity Au having a purity of 99.99% by weight or more and high purity S having a purity of 99.99% by weight or more
n were prepared and melted in vacuum, and the resulting molten metal was cast into a high-purity carbon mold to have a thickness of 12 mm and a length of 12 mm.
An ingot having a size of 200 mm and the component composition shown in Table 1 was produced. These ingots were heated at a temperature of 200
A ribbon having a width of 50 mm and a thickness of 30 μm was prepared by warm rolling at 50 ° C., the surface of the ribbon was degreased, and then polished to a surface roughness Ra specified in JIS B0601 shown in Table 1. The polished ribbon was slit and cut in parallel with the length direction to form a thin ribbon having a width w: 0.4 mm, thereby producing gold-tin alloy brazing materials 1 to 8 of the present invention and comparative gold-tin alloy brazing materials. Further, a commercially available product having the component composition shown in Table 1 has a width w of 0.4 mm and a thickness of 30 μm.
The conventional gold-tin alloy brazing material in the form of a thin ribbon of m was prepared.

Each of the gold-tin alloy brazing materials 1 to 8, the comparative gold-tin alloy brazing material and the conventional gold-tin alloy brazing material has a length of 0.4 mm.
A brazing material chip having a size of 0.4 mm × 0.4 mm × 30 μm is produced by cutting the brazing material chip on a pure gold plated substrate 3 as shown in FIG. And then held for 3 minutes to melt the brazing material chips 1 of the gold-tin alloy brazing materials of the present invention, the comparative gold-tin alloy brazing material and the conventional gold-tin alloy brazing material, and melted brazing material chips 1 is a maximum spread width (hereinafter, referred to as a maximum molten metal flow width) W of the molten brazing material 2 spread on the surface of the pure gold plated substrate 3, and a ratio of the ribbon width w of the brazing material chip 1 to the maximum molten metal flow width W ( (W / w x 100%)
Table 1 shows the results, and the wettability of the gold-tin alloy brazing materials of the present invention, the comparative gold-tin alloy brazing material and the conventional gold-tin alloy brazing material was evaluated.

[0012]

[Table 1]

From the results shown in Table 1, the gold-tin alloy brazing materials 1 to 8 of the present invention have a value of W / w × 100% larger than that of the comparative gold-tin alloy brazing material and the conventional gold-tin alloy brazing material. The gold-tin alloy brazing materials 1 to 8 of the present invention have better wettability than the comparative gold-tin alloy brazing material and the conventional gold-tin alloy brazing material. Therefore, the molten brazing material adheres to the entire lower surface of the semiconductor such as silicon and GaAs. It can be seen that reliable brazing can always be performed.

[0014]

As described above, the gold-tin alloy brazing material of the present invention has characteristics that are more excellent in wettability than the conventional gold-tin alloy brazing material, and the defective rate of the semiconductor device is also reduced. It is possible to reduce the cost and reduce the cost, and bring about an industrially superior effect.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for evaluating wettability.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brazing material chip 2 Molten brazing material 3 Substrate

Claims (3)

[Claims] 1. A surface roughness R defined by JIS B0601
A gold-tin alloy brazing material having excellent wettability, wherein a is in the range of 0.01 to 5 μm. 2. A composition containing Sn: 10 to 30% by weight, the balance being composed of Au and unavoidable impurities.
Surface roughness Ra defined by 0601 is 0.01 to 5 μm
A gold-tin alloy brazing material having excellent wettability, characterized by being within the range described above. 3. The gold-tin alloy brazing material having excellent wettability according to claim 1, wherein the brazing material has a linear, narrow band or chip shape.