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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