In this special case, the cross section showed that the joint between the
lead and the solder pad was IMC free, the frost like goldtin platelets were
on the upper side of the lead, superficial so as to say.
Inge
----- Original Message -----
From: "Joyce Koo" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 14, 2009 11:18 PM
Subject: Re: [TN] Gold/Tin Intermetallics, why are we afraid?
Agree. If you are the design authority and known the limits of the
application environment. The only danger is someone in thye future will
copy it without such a knowledge. Open a coomon law is the danger.
--------------------------
Sent using BlackBerry
----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Tue Apr 14 16:55:52 2009
Subject: [TN] Gold/Tin Intermetallics, why are we afraid?
These infamous IMCs are like parias or ghosts in most people's mind in our
business. I shocked our production guys recently by giving the advice to let
the boards go on. Large crystals and bad looking. But I always try to avoid
exaggerations. If no serious temp changes are predicted, nor any severe
power switching, why rework and risk introducing failures? The actual
components were very hard to rework, the cost had been unacceptable. I can
see many of you get the coffee wrong. I don't mean to spread quality
distractions, I talk about very few boards and a unique situation. My
statement was based on the fact that a gold tin intermetallic bond is
extremly strong and can last long, if not exposed to what I pointed at
earlier. I expect to be hammered down in the shop floor until only the nose
is visible....
Inge
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