Peter,
Check the shielding.
Werner

 


 

 

-----Original Message-----
From: Pete <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, Mar 22, 2011 11:18 am
Subject: [TN] Fabrication failures in one area of board?


We are trying to get an RF board functioning, and are having difficulties in the 



same area of a couple boards.  The circuit turns on, but with drastic 

performance differences



This board has 4 identical TX Channels, Channel 1, at the edge of the board 

works every time, but as we move inward, we experience more failures.  

Channel 4, at the center of the board will not perform properly on any board.



A visual examination doesn't show any differences that might impact 

performance.  The soldering process looks OK.



Is there something that could likely vary in the fabrication process that might 

cause this?  It's (supposed to be) a standard 170Tg, non-dicy, RoHS fab.  

High copper density, but the center channels are near an area of less copper 

density.  Could an epoxy curing variation occur, that might impact getting a 

consistent dielectric result?  What should I be looking for?  These boards were 

not ordered from our qualified vendor, and I have some concerns.  We had 

issues with them before.



Pete



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