Q:   How much growth (or shrink) should one expect land-to-land over
       a 16" distance? This has nothing to do with drilling; just master
       pattern to actual board size...

A:  I believe that's called stretch effect, the  bigger the board gets the 
more severe the growth (or shrinkage) it will have. The stretch also depends 
on the board house and board thickness. The best way to minimize stretch 
effect is to group components which require tight tolorance into the central 
location of the PCB.

Thanks

Michael Yuen


 ----------
From: TechNet-request
To: technet
Subject: dimensional question
Date: Tuesday, April 23, 1996 11:07AM

       The proliferation of sub .5mm peripheral leaded SMD's is causing
       assembly people to look at the overall size relationship
       between the master data and the actual board. When solder paste
       is stenciled on larger boards (say, 12-16"), the stencil image
       many times will not match the land pattern, causing shorts in the
       fine pitch area.
       My question:
        How much growth (or shrink) should one expect land-to-land over
       a 16" distance? This has nothing to do with drilling; just master
       pattern to actual board size...
       Thanks,

           marko