Experience has shown that LPI soldermask over pre-conditioned bare 
     copper has worked the best.  
     BW
     


______________________________ Reply Separator _________________________________
Subject: Re: Unidentified subject!
Author:  [log in to unmask] at uucpmail
Date:    11/19/96 05:31


     
     
     
     
  We do copper pours on FR-4 boards and have run into similar problems. 
  With a dry film type of mask you will get peeling unless you hatch the 
  copper. LPI works great, so that's what we use now. If you absolutely 
  have to have solid copper pours, you'll probably have to pay the higher 
  price for the LPI.
     
  Andy Buonviri
  ([log in to unmask])
     
  >We recently completed a single sided FR-4 design with a large area that 
  we "poured" copper into.  Two of our three high volume board shops said 
  no problem >when they reviewd this design. However our third house said 
  that it there is a possibility of a problem because we use a screenable 
  solder mask and they have a >worry about possible flaking of the mask on 
  the large copper area.  They recommended two ideads:
  >
          1.  Hatch the copper pour instead of leaving it solid.
     
  >Our answer to this? (Ameritech Commercial guy) ....MMMMM.......NO.  We 
  need it there for RF and ESD reasons I can't discuss.
     
          2.  Hatch the solder mask every 1/8 of an inch.
     
  >Again our answer to this is .....MMMMMM.......No.  This would gobble 
  solder out of our wave machines for no good reason.
  >
  >So we said how about LPI and they said sure for a significant price 
  increase.  Out of the three board houses this is the one who always gives 
  us the best product >at the cheapest price with the least amount of 
  rejects.
  >
  >SO WHAT DO WE DO NOW ?  We want to continue to use the solid copper pour 
  feature on future products.
  >
  >Your thoughts would be appreciated.
     
     
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