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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Multiple reflow cycles

Wes

#23790

Multiple reflow cycles | 13 March, 2003

Does a third solder reflow compromise component and solder reliability? We find that the only way to rework a particular BGA without warpage is to reflow the entire board.

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#23791

Multiple reflow cycles | 14 March, 2003

Hi, It's not recomended to do more reflows.Reliability of the boards decreases and a lot of defects appear.Try to repair other way- hot air or something like that.(main is to be local)

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Sudhir

#23836

Multiple reflow cycles | 19 March, 2003

I would suggest to have a rework station to rework only a single component we are having a genrad rework station to do these things

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#23840

Multiple reflow cycles | 19 March, 2003

Vapor Phase process can do reflow from 4 to 5 times!

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Rob_C

#23841

Multiple reflow cycles | 19 March, 2003

I would suggest creating a special reflow profile, heating the board up to 130C about 50 c below eutectic point (183C). Then applying heat to only the BGA, this will prevent thermal shock to surrounding components.

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RDR

#23846

Multiple reflow cycles | 20 March, 2003

Are you warping the BGA or the PCB?

Russ

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MA/NY DDave

#23858

Multiple reflow cycles | 20 March, 2003

Hi

I don't think I will enter this too much except for one of your questions.

YES multiple reflows affect reliability. Heck most everything affects reliability.

Aggressive Heat cycles or Heat always affects the final MTBF reliability number.

The question is: Is the Reliability degradation acceptable.

YiEng, MA/NY DDave

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Grant

#23884

Multiple reflow cycles | 21 March, 2003

Hi,

I can verify that, and we have done 2 or more reflows with prototypes, using vapor phase reflow, and because there is no oxygen, the result is good, and you cannot tell the difference between the first reflow, and the 3rd.

We are getting a vapor phase reflow oven for prototyping just because of this advantage, and all our tests have worked out very well. We even de-soldered a large PGA component by placing the board in the oven upside down, until the part fell out of the board.

It's a nice process for rework, as long as no modification wires have been added to the board, otherwise the wires fall off!

Regards,

Grant

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Reflow Oven

reflow oven profiler