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]