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Gold/Tin eutectic plate solution

2001

Hi there,

I am try to look for some kind of Gold/Tin alloy solution for electroplating to achieve the 80/20 eutectic solder, where can I have and what's the criteria for plating control.

Your inputs are highly appreciated.

Marcus C. Liang
- Atlanta, Georgia

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I never heard of a commercial bath, and it might be a very brittle composition if it can be plated at all.

  
Tom Pullizzi
Falls Township, Pennsylvania
2001

Look in Lowenheim's "Modern Electroplating" [on AbeBooks, eBay, or Amazon affil links] for three references.

James Watts
- Navarre, Florida
2001

Eutectic of solder and gold occurs at a fraction of a percent of gold. It is very brittle. Goldie and Reid have covered this topic in their book.

Yashawant Deval
electroplating shop - Pune, Maharashtra, India
2001

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2001

The company I work for has about finished developing the chemistry to achieve the eutectic composition. So far we've been trying to get the plated gold down to 80% from about 85%. The strategy in formulating arose from that used in our developing lead-free tin (with a little silver and/or copper).

Otherwise there are several commercial baths. The direct current plating formula appears to be hacked out and stretches to achieve eutectic composition, i.e. is too difficult to control. Another uses pulsed deposition and is also newly introduced. One final electroless process awaits funding for derivation of the tin as gold has been done. The object here is to have a stable solution which turns eutectic at a narrow temperature range. Let me explain. The process consists of stable liganded ions dissolved into a non-aqueous solvent. Evaporation of solvent leaves the salt film. Application of 150-250 deg. heat drives off the ligands resulting in uniform thin film metal placement. Plating occurs on anything and alloys have been done, just not the 80/20. I would be glad to offer any information-just write.

Steve Koelzer
- Sunnyvale, California, USA

I was also investigating the possibility of depositions of Au/Sn alloy solders on metal surfaces for die bonding purposes. Have found two companies that say they can do this successfully up to 20 microns thick, with mirror finish. I am in the process of checking this out now. There may be hope after all.

Elaine Pennington
- Forsyth, Missouri
2003

There's a new process which uses the PGC gold salt and of course tin but has a little cyanide. It's a good, quick electroless which can get dialed in for constant production to just about any composition of the gold-tin alloy. It's much faster than electroless gold.

Steve Koelzer
- Sunnyvale, California, USA
2003