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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Tomb stoning

Sultan Mahmood

#16976

Tomb stoning | 22 December, 1997

WE have a problem of tomb stoning in our smd assemblies during curing process of the boards in our Infra Red Soldering bath. Would you like to give us solution how to resove this proble? Thankyou Regards

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jergog

#16978

Re: Tomb stoning | 22 December, 1997

do a good edit on the smt machines | WE have a problem of tomb stoning in our smd assemblies during curing process of the boards in our Infra Red Soldering bath. Would you like to give us solution how to resove this proble? | Thankyou | Regards

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Jon

#16977

Re: Tomb stoning | 30 December, 1997

I suggest that you look at a few things: 1) The SMD pads may be too small for the part. Try to conform with the IPC standards in pad design. 2) The parts may be misplaced during the placement process. Tweek the placement program and if that doesn't work then check your Gerber data for X or Y centroid data issues. 3) Your IR solder bath system may have a transport problem, (ie, jerkiness, etc), thereby causing some shifting in the parts during a critical stage in the transport. 4) IR by its nature has some color emissivity problem and terefore is color sensitive. (the dark parts may be reaching reflow temperature first and the light colored parts are reaching reflow last). Hope these might give you an idea for the eventual resolution. Good luck JON | WE have a problem of tomb stoning in our smd assemblies during curing process of the boards in our Infra Red Soldering bath. Would you like to give us solution how to resove this proble? | Thankyou | Regards

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Bill Fluegel

#16979

Re: Tomb stoning | 18 February, 1998

| do a good edit on the smt machines

| | WE have a problem of tomb stoning in our smd assemblies during curing process of the boards in our Infra Red Soldering bath. Would you like to give us solution how to resove this proble? | | Thankyou | | Regards I had that problem and it was caused by a combination of to much solder on the pads and the pcb heating faster on one pad due to the direction of travel in the reflow oven. we started running the board in a direction that let both pads for that part reach each temp zone at the same time and this fixed it.

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