Scratching around for some other ideas:
 
1) Bismuth has been added to ordinary solders to reduce inspection glare by giving dull joints.
2) Could it be a price thing? 43% tin is less expensive than 63%, this practice may go way back to when this could have been a significant benefit in wave soldering
3) Err...That's it, there are some [mostly minor] differences in mechanical properties but is hard to see what benefits would come from them in a regular PCB application
 
 

Mike Fenner
Indium Corporation of Europe 
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen R. Gregory
Sent: Friday, June 08, 2001 8:53 PM
To: [log in to unmask]
Subject: Re: [TN] Low Temp Solder with Bismuth??

Hi Rick!!

You're right, a 43/43/14 is a standard low temp alloy. 43% tin, 43% lead, and
14% Bismuth. The liquidous is 163 C., and solidus is 144 C...

The only reason I can think of using it is that there must be something on
the board that is heat sensitive...other than that, I can't think of any
other reason.

-Steve Gregory-


Hi,

We have a customer who is using a low-temp solder (43-43-14) which I think
is some alloy containing Bismuth among other things.  The problem we have is
that no one currently at the company seems to know quite why this was spec'd
in to the process and I don't have any familiarity with it.

Can anyone offer insight or resources to research this alloy and why I might
want to use it?

Thanks in advance.


Rick Thompson
Ventura Electronics Assembly
2655 Park Center Dr.
Simi Valley, CA 93065

+1 (805) 584-9858   x-304  voice
+1 (805) 584-1529 fax
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