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Printed Circuit Board Assembly & PCB Design Forum

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SRT -1000 BGA rework system

Vijay

#25294

SRT -1000 BGA rework system | 30 July, 2003

Hi, I am observing warpage in the PBGA during reflow in rework machine.Reflow profile is std. (Peak temp is 214 deg C using 63/37 paste). Please advise what should be the gap between the nozzle and the BGA body during reflow process in SRT BGA rework system? Thanks,

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Dean

#25305

SRT -1000 BGA rework system | 30 July, 2003

I have been using a srt-1000 since 98.

My guess is your heating up the part too fast. What is your heating rate (deg. C per second)? PBGA's do warp. Your profile should mimic your smt process (assuming you have no warping there). Also, check with your solder paste manufacturer for profile recommendations.

I position our nozzle 0.050 to 0.100 inch above the part. Hope this helps.

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Vijay

#25306

SRT -1000 BGA rework system | 30 July, 2003

The profile is enclosed.The PBGA is 37x37 mm.I am keeping the gap about 4-5 mm.The profile meets the solder paste spec.Peak temp is 211 deg C,Above melting point 77 sec. rate of heating <2 degc /sec.

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RDR

#25309

SRT -1000 BGA rework system | 31 July, 2003

Are you baking the parts prior to installation? I have found that this will help in some cases.

Russ

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Kris

#25321

SRT -1000 BGA rework system | 31 July, 2003

Hi,

Are you printing the paste uniformly ?

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#25324

SRT -1000 BGA rework system | 31 July, 2003

A couple of things you can look into

1. The proper bottom pre-heat of board. If you are applying only direct hot air to BGA without preheating can cause BGA's to warp and collapse un-even.

2. Moisture on you BGA's. If BGA's were not properly packaged moisture can hot air balloon the BGA.

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Vijay

#25326

SRT -1000 BGA rework system | 31 July, 2003

Yes we are baking the boards and the BGA. Using a CDM material pallet to hold the PCB as clamping is a problem without that.

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Vijay

#25327

SRT -1000 BGA rework system | 31 July, 2003

Yes the paste printing is uniform. I have not tried out paste flux yet.

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Dean

#25355

SRT -1000 BGA rework system | 4 August, 2003

If you lay a flat edge on the PBGA, it is visibly warped? How much of a warp? 0.001, 0.010, 0.050 what? What is your pcb temperature just prior to entering the spike process (zone or step or what ever you call it)? Is it between 165 and 175 C?

If not, you are probably shocking the part with the temp spike.

You might consider a ramp to spike profile... Hope this helps.

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