Hi Victor-

As long as solder doesn't wet to the conductor, it is considered masked.  I can't count the number of times "solder mask" has been confused with "insulator"!  Did it myself a couple of times until I got caught and then realized it was only a mask.  If you need guaranteed thickness without pinholes on an outer layer, use polyimide "coverlay".

On the other side of thickness control, I've seen lumps which prevented stencil gasketing.

I believe IPC advises on chemistry/compatibility issues of mask, as well as incomplete masks which don't do an effective job of masking solder, but not thickness.

Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Friday, February 28, 2014 8:07 AM
To: [log in to unmask]
Subject: [TN] Solder mask thickness

Fellow TechNetters:

   What are some bench mark thicknesses for solder mask coverage over external conductors/signals.   I have not seen an actual value in any of the IPC STD that I have read, IPC-2222, IPC-6012, IPC-SM-840.   I believe that that are three different manufacturers.

Victor,


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