We are planning to do a study on dimensional stability of pwbs. Right now 
our focus is on the laminate material and cores. We are seeing different 
amounts of shrinkage depending on design complexity, cloth type, copper 
etc...In addition this shrinkage appears to be inconsistent from lot to lot.

We understand that resin content of prepreg is a factor. 
In reference to Printed Circuts Handbook by Coombs (sec. 23.2.3) 40-60 %
resin content by weight is desirable. What happens to dimensional 
stability if we go outside that range? What kind of SPC are you doing to 
control resin content?                                                    

We would also like to know what the main variables in prepreg 
fabrication (relative to dimensional stability) are, and how the rest of 
the industry is controlling these variables.

All input is highly appreciated.

Chris Davison

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