flaky white powder....wow! Sounds like alpha tin, otherwise known as tin
pests. You better hope not though. Although, I really can't imagine alpha
tin happening, you better make sure it isn't.
Thanks
Ryan Grant
Advanced Technology Engineer
MCMS
(208) 898-1145
[log in to unmask]
> -----Original Message-----
> From: Hollandsworth, Ron [SMTP:[log in to unmask]]
> Sent: Monday, July 31, 2000 3:14 PM
> To: [log in to unmask]
> Subject: [TN] Subj: White Tin
>
> Hello TechNet:
> We performed some experiments on Immersion White Tin boards and found the
> following . . . . First, we had no problems with solder paste
> application.
> Second, no problems with vision systems, etc., and part placement. Third,
> solder joints looked pretty good . . i.e. . no problems. Here is the
> kicker. The mounting holes on the top side were white tin. The mounting
> holes need to be very flat for good contact so we do not apply solder
> paste
> to these holes. The white tin, after exposure to humidity of the
> environmental chambers looked very oxidized and a flaky white powdery like
> substance was observed. Also under some RF type connectors, the white
> powdery like substance was observed. The powdery like flaky substance did
> not show up under any other components only the gold RF connectors.
>
> What experience have any of you had with the immersion white tin process?
> Any ideas, thoughts, etc., on the powdery white substance??? We are going
> to
> have our "product assurance forensic lab" analyze it and see what they
> come
> up with, but we also thought it a good idea to tap the intelligence of the
> TechNet World as well.
>
> Ron Hollandsworth
> ITT
>
>
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