Hi Greg!

Tough problem because the higher the silver content, the higher the
melting point, at least among the alloys I'm imagining at the moment.  I
guess you need to consult a chart.

Anyway, the higher temperature may cause more leaching than the slightly
decreased appetite for silver.

Wayne Thayer 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Greg Major
Sent: Monday, June 25, 2007 6:42 PM
To: [log in to unmask]
Subject: [TN] Silver Leach

Hello TN,

When soldering to a ceramic board with silver tracks sintered to it, has
anyone come across a requiremnt to use a higher silver content than SAC
to prevent leaching of the silver?

I'd assumed that the (almost) 4% silver in SAC would have been more than
enough to make the solder and substarte virtually electro-chemically
equal and prevent leach/dissolution.

Pre pb-free, I remember reading about folks using 96S alloy (Tin & 3.7%
Ag) to solder to such boards.

Given the liquidus point of 96S, I wouldn't have thought there would be
much differnce with SAC.

Any ideas anyone?

cheers

Greg

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