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Date: | Fri, 21 Jun 96 12:15:29 EST |
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I would think that up to 0.0005" (0.5 mil) is overkill. Our process
uses a bright tin plate and the minimum is 0.0001". The 0.0003"
sounds like the thickness needed for solder plating.
Be careful when switching from solder to tin, especially if switching
to matte finish tin. A high caustic (generic) stripper for the dry
film can easily cause pinholes in your copper. This isn't likely when
using a bright tin.
Also, there are multiple suppliers for this chemistry. Ask around
with the suppliers who give you good service.
MB
______________________________ Reply Separator _________________________________
Subject: FAB Re Tin plt. instead of Sn/Pb
Author: [log in to unmask] at SMTPLINK-HADCO
Date: 6/18/96 03:45 PM
Paul.
If I understand your process, you are only going to use tin as an etch resist
and strip it and go SMOBC
A supplier down in Conn., MacDermid, sells a tin electroplate formulation
used mainly for your type of process and is one of the cheapest based on a
tin sulphate bath. You will find the tin stripping easier and faster than
the tin/lead. Obviously, after etching don't fuse it and don't use
solderbright. The plating is pretty normal and you can convert your tin/lead
process and pre-tin/lead pickle using the same process line and change the
acid predip accordingly.
The tin thickness minimum is about 0.0003 inch, but to be safe a 0.0005 is
often used.
Your process removes all of the tin plating and you are not concerned with
whiskers, slivers and gray tin. If you are going to use the tin as a final
finish, put another note on technet and I can furnish additional information.
Phil Hinton
[log in to unmask]
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