Hi all,
I have triggered some BGA soldering issues last weeks and got superb responding! We  have learnt a lot!. Among answers one warning  not using concoat under very large BGAs, could cause pumping effects. Guess Tech-Shot could answer as well, but more gurus  at TechNet. Graham N, he must at least have a refresher for me. Got this b4:
1. try skip concoat, best living for BGA solderings
2. if using concoat, always underfill 100% first
3. if using concoat and no underfill first, you'll get closed in gas and contaminations and CTE mismatch >disasters

So, my question is: is 3 above reality for some of you? Don't your balls like such pumping?

Thx in advance
Ingemar Hernefjord
Ericsson Microwave Systems

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