Hi Bryan-

I've had problems with those.  I think the main problem is stripping the tin oxide.  I speculated that perhaps because I was using Rosin flux and Pb based soldering temperatures, it didn't strip that oxide as well or quickly as higher temperatures with more highly active aqueous fluxes.  Try extending the time above liquidus.

On the other hand, if you only have to make one, you can hand tin, or even bump, the pads on the QFN, and then reflow.  For me, that has always led to the most void-free joints on these parts.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kerr, Bryan (UK)
Sent: Wednesday, August 07, 2013 7:38 AM
To: [log in to unmask]
Subject: [TN] QFN solder voiding

Hi Folks

I am familiar with most of the industry thoughts and standards on voiding in the centre paddle of QFN's but has anyone any experience with voiding in the peripheral pads ? From my experience this can vary fairly widely and there are no standards that I know of which would cover this - unless anyone can enlighten me ?

Bryan Kerr
Principal Quality Engineer
CMA Lab and Process Engineering
BAE Systems Maritime Services
Manufacturing Hillend
Hillend Industrial Estate
Hillend
Nr Dunfermline
Fife
Scotland
KY11 9HQ
01383-836097
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