TO:[log in to unmask]

PWB stretch or shrinkage seems to be the limiting factor for stencil 
printing of larger PWB's with fine pitch pad's. We use laser cut stencils 
and stencil printers with visual alignment but still have problems with 
larger PWB's.

What is reasonable to expect from PWB suppliers?
Does anybody know about a specification for PWB stretch? I would like to ask 
for a stretch / shrinkage tolerance depending on PWB size and smallest pad's 
on the PWB. What can be expected on FR4 boards without paying a premium? 
What can be supplied at higher cost?

Thanks in advance for any help on this

Klaus Giese
Siemens Energy & Automation
Johnson City, TN 37601
(423) 461 2459
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