The thread has drifted into brittle fracture due to 'gold
embrittlement'.
We have experienced 'gold embrittlement' at levels (0.25%) which are
well below the threshold said to be 'safe'.
Maybe Murphy did his bit to ensure that the gold didn't distribute
evenly through the joint and therefore the failure initiated at
concentration points. In our situation the important thing was to solve
the problem quickly so we made an assumption it was 'gold embrittlement'
and took to double dipping to get rid of the plated 'excess' gold. The
joints stopped failing after double dipping.
I would now say that we tend to have a belief that gold in solder joints
should be avoided.



Rex Waygood
Technical Manager
 
PartnerTech Poole Ltd 
Benson Road
Poole
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United Kingdom
 
Tel: +44 (0)1202 674333
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DDI: +44 (0)1202 338222
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www.PartnerTech.co.uk

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: 16 January 2008 13:52
To: [log in to unmask]
Subject: [TN] Solderability of Tin-Gold Intermetallic

Technetters,
We all know that the tin-copper intermetallic has terrible
solderability.  I also know there are high melting tin-gold solders.  My
question is: what is the solderability of surfaces of tin with small
amounts of gold (<4%) in it? As good as 100% tin, better, worse?  If
worse, how much so?
Bev
RIM

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