AuSn (Gold-Tin) Solder

Sumitomo Metal Mining’s AuSn (Gold-Tin) solder uses high-purity Au (4N:99.99%) refined in-house and is produced from melting and casting to high-precision press processing. Advanced rolling technology and high-precision press technology achieve ultra-fine processing with a minimum thickness of 10µm and an outer diameter size of less than 1mm.
Various shapes such as frames, washers, ribbons, balls, and plates can be processed according to customer requirements.

AuSn (Gold-Tin) solder is an alloy mainly composed of gold (Au) and tin (Sn) with excellent thermal and electrical conductivity. Due to its high Au content, it is used as a bonding material for electronic components requiring high reliability, such as crystal oscillators and optical communication devices. AuSn (Gold-Tin) solder has a melting point of 280°C, appropriate for high-temperature soldering, minimizing thermal impact on electronic components during bonding. Sumitomo Metal Mining has developed AuSn solder S-type with superior wettability compared to conventional products. S-type exhibits excellent wettability even on thermally oxidized plated substrates. This is due to a proprietary process reducing the oxide film thickness on the AuSn solder surface, effectively improving yield during step soldering and preventing void formation.

AuSn(Gold-Tin) Solder Wettability Test

Our developed product on the right shows superior wetting spread while retaining its shape.

Sumitomo Metal Mining’s AuSn (Gold-Tin) Solder series.
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In addition to being used as sealing material and solder material for crystal oscillators, communication devices, and semiconductor lasers, it is also used as electrodes for LEDs and mounting solder for electronic components.

What is the melting point of AuSn (Gold-Tin) Solder?

The melting point of AuSn (Gold-Tin) Solder is 280℃ for eutectic composition Au-20Sn, and for Au-22Sn the melting start temperature is 280℃ and the melting end temperature is 315℃.

What are the precautions for use?

Depending on the components you use, if you use Au metallized (plated) components, the Au on the surface of the components diffuses into AuSn when melted, increasing the Au concentration in AuSn, precipitating a phase with a high melting point, and inhibiting good wetting spread. Therefore, when using Au metallized components, consider this and Au-22wt%Sn is the recommended composition.

Can AuSn (Gold-Tin) Solder be made into a wire?

We are not currently manufacturing wires. We can provide ribbons with a width of 0.3mm and a thickness of 15µm.

Is AuSn (Gold-Tin) Solder lead-free?

Yes, AuSn (Gold-Tin) Solder is an alloy of Au and Sn and is an environmentally friendly lead-free solder material.

Does AuSn (Gold-Tin) Solder contain RoHS directive substances?

It does not contain them.