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BGA post SMT reflow?

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#59530

BGA post SMT reflow? | 13 August, 2009

I'm new to all this...

we have a board with one BGA blue tooth device. one test for the board is an rf test that measure successful packet transmission. we find that we get much lower error rates if we "reflow" the BGA with a heatgun. We do this after the board is completely finished and in test. We will clean any conformal coat off, then hit the BGA with the heatgun. Appox 20-30 seconds and 260C. The BGA is small, 60 balls. We are finding that the RF device is sensitive to many factors including conformal coat thickness.

Has anyone ever heard of a post-SMT reflow process aimed at BGAs?

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#59536

BGA post SMT reflow? | 14 August, 2009

It's some time difficult to control process when using a heat gun. What is the intent of using the heat gun after test?

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#59538

BGA post SMT reflow? | 14 August, 2009

> It's some time difficult to control process when > using a heat gun. What is the intent of using the > heat gun after test?

we agree... the heat gun method was an experiment. We are planning to us a hot air re-work station. The intent is to re-melt the solder balls. After the heat gun (~250C, 20 seconds), our rf performance (blue tooth frequencies) markedly improves. Is our smt process inadequate? probably, but we have tweeked it with no positive results. the only positve result is seen with the heat gun method... have not tried re-flowing the bga on a hot-air rework station yet. The post smt reflow seems, at this point, to be magic...!

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#59541

BGA post SMT reflow? | 15 August, 2009

It would be nice, save you money, improve yield, improve reliability, etc. if your reflow process was more effective. It sounds like you're not getting the part hot enough during reflow soldering. Tell us about: * Measured temperature on this bluetooth component * Solder paste * Material of the component leads * Material of the solderability protection on the board

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