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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Large board BGA rwk

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RDR

#38914

Large board BGA rwk | 9 January, 2006

How are people getting BGAs reworked on boards that are 15"x15" at .06" thick? The BGAs are pretty much in the center of these assemblies. We have just received these and I cannot keep from warping/bowing as much as 1/2" at the heated area. Our bottom preheater is 4" x 4" in size and I believe that this is the problem. The PCBA is hot in the middle at the BGA and cold at the edges, somethings got to give somewhere? i have tried long and slow to short and fast profiles to no avail.

I do have pretty good luck with these large boards when the parts are out at the edges.

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Mike

#38917

Large board BGA rwk | 9 January, 2006

Basically the same exact way as a much smaller board. The only difference is the profile. Most of our boards are 0.063" thick. Looks like you found your problem. If the edges of the board are cold relative to the rework site (high difference in temperature) warping will occur. Try creating a profile so that you preheat at a higher temperature for a longer period of time before having the topside heater kick in. The preheater area does sound small so it very well may be that your system cannot handle such large boards.

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RDR

#38930

Large board BGA rwk | 10 January, 2006

Thanks Mike, Unfortunately I am limited to the amount of time I can run preheat along with the limitation of only two different settings/cycles. Looks like its time to get a higher end rework station.

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