I received the photo - I realize Technet did not.  The one surface land does
show over hang, but the one on the bottom from another coupon shows NO
overhang.

The one with overhang also shows severe UNDERCUT of the solder mask next to
the land.

I am puzzled by the "scotch brite" comment as I can think of no reason for
using this in a SMOBC product.  Any and all tinlead plating should have been
stripped off prior to cleaning and solder mask application, The overhang of
copper that was present on the top coupon would not have been removed by an
abrasion process.

The real proof would be seeing what the sample looked like in the "as plated"
tin/lead condition and finding out why an abrasion process was used.  The few
times I have used an abrasion process only caused the overhang to become
splinters that then came loose later on and caused problems.

The undercut of the solder mask is also a potential threat for trapping
contamination later on during HASL or assembly processing.

Susan Mansilla
Technical Director
Robisan Laboratory, Inc.
6502 E 21st Street
Indianapolis, IN  461219
www.robisan.com
317-353-6249


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