Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


BGA vrs CGA....

#25767

BGA vrs CGA.... | 19 September, 2003

OK, so is anyone qualifying CGA's yet? Our first batch of CGA qualification is not going too well. We stuck with the teardrop shaped pad but the solder fillet is not as big as expected. What size pads is anyone using, i'm getting conflicting information from IBM / others. We have small fillets, which look void-free but we haven't microsectioned yet, they are definately connected and likey to fail in vibration. I have pictures too if anyone's interested.

Chrissie

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RDR

#25768

BGA vrs CGA.... | 19 September, 2003

We usually use a pad that is the same size as the ball. And use a stencil thickness of 7+ mils. Why the teardrop?

Russ

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Gabriele

#25775

BGA vrs CGA.... | 20 September, 2003

Few questions:

- wich type of C-CGA ? (CAST or CLASP column to ceramic attach) - column pitch ? - column count ? - capped (with lid) ? or capless (c4 die on top)? - PCB board zize and thickness ? - volume of solder paste ? - Clean or not Clean solder? - stencil thickness

Ciao....Gabriele

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Gabriele

#25776

BGA vrs CGA.... | 20 September, 2003

Few questions:

- wich type of C-CGA ? (CAST or CLASP column to ceramic attach) - column pitch ? - column count ? - capped (with lid) ? or capless (c4 die on top)? - PCB board zize and thickness ? - PCB copper finisch ? (OSP,HASL, ENIG, etc) - volume of solder paste ? - Clean or not Clean solder? - stencil thickness

Ciao....Gabriele

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#25782

BGA vrs CGA.... | 22 September, 2003

We were having void problems with heat transfer down the via's (24 layer boards, shed loads of planes). So we drew the via away from the centre into a teardrop pad. Void's gone!

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RDR

#25795

BGA vrs CGA.... | 22 September, 2003

Cool!!!! I'll have to remember that one.

Russ

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#25807

BGA vrs CGA.... | 23 September, 2003

Look out for shorts due to too big pads / balls colasping too much / too much solder paste though. there's a fine line and it's expensive to find it!

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