Clear Soldermask or Unpigmented Soldermask will hold a very tight 
     tolerances.  It is typical to see 2 mil registration with this type of 
     soldermask.  Most manufactures of LPI soldermask offer Clear version.  
     It has also been approved by IPC on IPC-SM-840C.
     
     
     
______________________________ Forward Header __________________________________
Subject: Soldermask-misregistration
Author:  [log in to unmask] at corp 
Date:    9/5/96 11:48 AM
     
     
     Does anyone know if there is a particular soldermask that will keep 
     tighter registration.  For instance, is a liquid soldermask able to 
     keep a tighter registration than a dry film?  Currently, we allow for 
     a 4mil misregistration in our soldermask opening.  We would like to 
     bring that number down to 2 or 1mil on a very tight board we have 
     (that has cooper covering the ground pads-causing the ground pads to 
     have a larger shape) without having the manufacturer scrap alot of 
     boards.  Our plating is immersion nickel/gold.
     
     Thank-you
     
     Charlene Dwyer
     [log in to unmask]
     
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