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Pb free BGA voids

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Pb free BGA voids | 2 May, 2006

Good morning all. I'm trying to find some help on my voiding issue on my lead free BGAs. I am using a Heller 8/2 zone oven, and using Qualitek solder paste. I had listened to a tech representing another solder company, who told me to make the joints nice and "shiny", I should peak out around 247-ish. This is obviously too hot, as I have major (40%+/-) voiding on my BGAs. I'm going to go again, this time peaking around 237 and trying to get in and out above 217 around 75 seconds. Sound reasonable? I'd surely appreciate any advice or help! Thanks much!

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Bob R.


Pb free BGA voids | 2 May, 2006

Be careful about taking any generic advice and trying to use it to reduce voiding for your particular paste with your particular boards. I've done a few literature searches over the years on causes/cures for BGA voiding in the SnPb world and found a dozen different variables people claimed to have an effect. Often different articles were contradictory on which way to turn any given knob. When I started doing my own factorial experiments on both SnPb and Pb free BGAs I found that pastes from different suppliers reacted differently to the same knobs. Generic statements like "ENIG boards have higher voiding" aren't true. Factors effecting voiding are very paste specific.

Your best quick term resource is your paste supplier. In the long run it'd be best to run your own experiments.

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Pb free BGA voids | 2 May, 2006

Yeah, that's what I'm doing now. I have it now peaking around 235, with about 70 sec. above 220C. (220C is the reflow temp, according to manufacturer. I've always used 217C for Pb free) Wish me luck. Thanks!

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