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Recommended TG material for CCBGA , CBGA and PBGA's

Paul Dansereau


Recommended TG material for CCBGA , CBGA and PBGA's | 26 February, 2003

I will be building a board, about 8 X 12 , .062" thick using a standard FR406 stackup. It has a variety of devices, including CCBGA , CBGA and PBGA's. Given the challenge of developing a reflow profile that will accomodate both ceramic and plastic BGA's, is the FR406 material correct, and is there any benefit to using a higher Tg stackup? Thanks for your inputs.

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Recommended TG material for CCBGA , CBGA and PBGA's | 1 March, 2003

You're correct that the FR4 is probably the best choise. The majority of the problems in developing your reflow recipe is going to come from the CTE mismatches in the CCBGA , CBGA and PBGA that you put on the board.

The other side says given the problems caused by the thermal mismatch of the components, going to a higher Tg epoxy is a cheap and easy way the reduce some of the variation caused by the board.

Alternately, Earl Moon used to post responses to questions like this on this forum. He's very smart on board fabrication issues. If you can't find his email address in the fine SMTnet Archives, I'll try to find one.

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Recommended TG material for CCBGA , CBGA and PBGA's | 3 March, 2003


I see David F already gave a good answer.

The basic advantage, if you can afford it, is a more stable PCB during the soldering process. Higher Tg enables this. Also some materials serve to match CTEs (coefficient of thermal expansion) a bit better so that during differential heat expansion and then cool down less residual stress is created in those outer joints.

In some industries where the PCB is a SQUAT contributor to final value, higher / better Tg materials are used frequently to enable better manufacturing and reliability.

If you are concerned and can afford it, talk to your laminate supplier.

YiEng, MA/NY DDave

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