Bingo! This is the type of answer I was looking for. Thx.
Bev
RIM
----- Original Message -----
From: Wenger, George M. <[log in to unmask]>
To: Bev Christian; TechNet E-Mail Forum <[log in to unmask]>
Sent: Wed Jan 16 09:20:00 2008
Subject: RE: [TN] Solderability of Tin-Gold Intermetallic
Bev,
I'm not sure I can give you a direct answer for tin but I can give you
an answer for SnPb solder. In the RF world there are lots of gold
plated components that can have very thick gold (>2.5um). Because of
solder joint reliability reliability concerns it has been standard
practice to pre-tin (expose to SnPb wave or use a double dip in to
solder pots) to dissolve most of the gold) and the resulting pre-tinned
surface does contain some gold. The amount of gold remaining in the
solder on the surface of the components is dependent on the quality of
the pr-tinning process. However, we've seen many surfaces of pre-tinned
components with up to at least 4% gold and have not seen any
solderability issues.
Regards,
George
George M. Wenger
Senior Principle FMA / Reliability Engineer
CommScope / Andrew Wireless Solutions
40 Technology Drive, Warren, NJ 07059 (908) 546-4531
[log in to unmask]
-----Original Message-----
From: Bev Christian [mailto:[log in to unmask]]
Sent: Wednesday, January 16, 2008 9:04 AM
To: Wenger, George M.; TechNet E-Mail Forum
Subject: RE: [TN] Solderability of Tin-Gold Intermetallic
George,
Correct of course. That is what I meant. How about my question?
Bev
RIM
-----Original Message-----
From: Wenger, George M. [mailto:[log in to unmask]]
Sent: Wednesday, January 16, 2008 9:03 AM
To: TechNet E-Mail Forum; Bev Christian
Subject: RE: [TN] Solderability of Tin-Gold Intermetallic
Bev,
I think I would re-state your first sentence. "We all know that
tin-copper intermetallic that has come to the surface and been exposed
to the environment has terrible solderability." I view tin-copper as
the glue layer between solder and copper when solder touches copper and
forms an intermetallic the solder above the intermetallic must wet it
otherwise it would fall off.
Regards,
George
George M. Wenger
Senior Principle FMA / Reliability Engineer CommScope / Andrew Wireless
Solutions 40 Technology Drive, Warren, NJ 07059 (908) 546-4531
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Wednesday, January 16, 2008 8:52 AM
To: [log in to unmask]
Subject: [TN] Solderability of Tin-Gold Intermetallic
Technetters,
We all know that the tin-copper intermetallic has terrible
solderability. I also know there are high melting tin-gold solders. My
question is: what is the solderability of surfaces of tin with small
amounts of gold (<4%) in it? As good as 100% tin, better, worse? If
worse, how much so?
Bev
RIM
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