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Reply To: | (Designers Council Forum) |
Date: | Wed, 12 Sep 2012 16:11:32 -0500 |
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Hello-
I'd like to ask how some of you are handling vias under a QFN package.
What I'd like to do is plug them completely from the bottom with epoxy.
Many high volume manufacturers will only use solder mask for plugging
vias, or charge a 10% increase in cost. The vias are required for thermal
relief under the part, so solder mask must be left open on the top. These
vias need to be filled or tented from the bottom to prevent solder from
wicking up during the solder wave process, after reflow. So far, using
only solder mask for plugging isn't working out very well. I haven't been
able to find a simple solution, everything I've read basically said yes,
this is a problem. But haven't found any solutions. One company has
offered a LGA pattern for an identical part, but this land pattern has
even more vias exposed under the LGA package, also for thermal refief. Any
suggestions?
Thank You So Much,
Kitty
Kitty Hines
The Chamberlain Group, Inc.
(630)516-6655
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