Some great comments on solder mask defined pads for BGA. First if people are trying to overcome lifting of pads during rework using this technique rework operators need re training. Over lapping resist pads is poor practice, it goes against the grain of basic stencil printing paste, i e the stencil seals with the pad during printing, or do you want to increase you under stencil cleaning. Most of the photographs that are seen showing cracking or crack initiation on BGA joints at the solder to pad interface are on thick masks >0.002" or on dry film used on the BGA components this is were the failures occur. Some of the photographs published in articles even show the failure at the BGA pads stating they are the board sites. I have conducted tests and had failures due to mask expansion, when a second party reviewed the photographs he made the mistake of thinking the failure was at the PCB pad turnthe picture up side down it is easy. If you are interested I will be conducting workshops at Nepcon West which include BGA, BGA Design and board requirments which are little different that for fine pitch board. After all a board with BGA will also include some fine pitch !!! Bob Willis SMART Group UK 2 Fourth Avenue, Chelmsford, Essex CM1 4HA. England. Tel: (44) 01245 351502 Fax: (44) 01245 496123 Home Page: http://