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December 1997

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Subject:
heeelp - NON-THERMAL RELIEVED VIAS AND COPPER PLANES
From:
Richard G Smith <[log in to unmask]>
Reply To:
TechNet Mail Forum.
Date:
Fri, 19 Dec 1997 17:09:46 -0600
Content-Type:
text/plain
Parts/Attachments:
text/plain (28 lines) 
     Been having some trouble with vias fracturing on plane layers of a
     PCB. The PCB is an eight layer board with four different voltage
     planes. On two of the planes the vias have thermal ties, the other two
     do not. The vias are fracturing on the two planes where a thermal tie
     is not utilized. It seems to be sporadic and only after the PCB is
     assembled which has at least three thermal excursions during assembly.

     The vias are .018 +-.003 and flooded with soldermask.

     Any comments/help/ideas why this is happening would be greatly
     appreciated.

     Thankyou,

     Rick

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