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11 BGA's 12-Layer nightmare

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#62501

11 BGA's 12-Layer nightmare | 21 August, 2010

What would You recommend?

PCB has 5 medium sized lead BGA packages on one side and huge lead - free BGA.

On the other side among other elements of course there are 5 big sized lead - free BGA Quad Gigabit Pulse transformers.

PCB plating: Ni/Au.

I did it like this: Lead free reflow process for the side with BGA transformers, then Lead process for the other side with 5 medium sized BGA's. After that huge - pb-free BGA mounting process on rework station.

Results were: Very good overall quality of solder joints, no failures on BGA packages on one side (5 medium lead, and huge pb-free). The transformers were the problem. Some voids occured.

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#62507

11 BGA's 12-Layer nightmare | 22 August, 2010

Hello, why you did not made it lead free the side with 5 medium sized BGA's ? that why you may been assembly and the large lead free BGA.

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#62508

11 BGA's 12-Layer nightmare | 22 August, 2010

5 medium sized BGA's are lead process rated only. Lead-free process would most likely destroy them

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#62515

11 BGA's 12-Layer nightmare | 23 August, 2010

Kill the engeneer

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#62528

11 BGA's 12-Layer nightmare | 25 August, 2010

Have the huge LF BGA reballed to leaded and assemble it with your leaded process. Time savings from using the rework station should pay for the reball if you're doing more than just a few.

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#62597

11 BGA's 12-Layer nightmare | 1 September, 2010

It's a very small series. There's already a decision to redesign the board to get rid of QUAD BGA transformers. We'll replace them with 2x transformers in other packages.

We'll also try to order lead-free smaller BGA's on the other side to unify the process.

Thank's for the advice. The most tempting was that one about killing the engineer ;-)

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