Bob,


 


Yes, that is one of the reasons. When vias are covered by
mask, the impurities (oil or gases or air...) trapped inside via hole got
heated up in the Assembly process making via holes to bulge out...seems like volcano
bursting. 


 


We use via plugging and via encroachment which avoids the
volcano bursting.


 




Thanks,


Raj.




----- Original Message ----
From: Silicon Valley Chapter - IPC <[log in to unmask]>
To: [log in to unmask]
Sent: Wednesday, 21 March, 2007 4:38:56 AM
Subject: [DC] Soldermask over vias?

I am sure this topic has been discussed before...
   
  What is the latest pros/cons concerning the masking of vias?
   
  At one time there were concerns about trapped air/gas and the possibility
  of it popping. Is this fact or myth? 
   
  Any information with supporting data would be most appreciated.
   
  Thanks in advance!
   
  Bob McCreight, C.I.D.
   
  
 

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