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Re: lead free solder
snipped-for-privacy@aol.com says...
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I think I have mentioned "purple plague" here before.  
https://en.wikipedia.org/wiki/Gold-aluminium_intermetallic . I learnt  
about it decades ago when working on experimental conducting films.

I thought that gold was tricky to solder precisely because it did tend  
to dissolve unless the solder was already loaded with gold.

Mike.

Re: lead free solder
On Saturday, April 30, 2016 at 6:00:05 PM UTC-4, MJC wrote:

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Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve.  

Peter Wieck
Melrose Park, PA  

Re: lead free solder
snipped-for-privacy@aol.com wrote:

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** In fact gold dissolves readily in tin and hence solder.  

Normally, gold plated parts have a nickel underlay which does not readily dissolve to form an alloy with solder. This results in joints that have poor mechanical strength.  

https://en.wikipedia.org/wiki/Gold_plating#Soldering_issues

http://www.indium.com/blog/intermetallics-in-soldering.php


....   Phil  




Re: lead free solder


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Within the EU; hobby use and repairing originally lead solder equipment is  
among the exemptions.

Never bothered swotting up on the laws elsewhere, but I think America and  
Asia comply with RoHS purely so they can export to the EU.

RoHS certification is expensive enough, but certification guaranteeing that  
cross contamination can't happen in a manufacturing plant that uses both  
processes, is much more costly - its much cheaper to impose blanket  
compliance with RoHS, even for goods that don't have to comply.

Mixing them depends on individual compositions - visual appearance of the  
finished joint is a good indication whether you got away with it.  


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