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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Solder Bursting



Solder Bursting | 14 February, 2004

We are currently experiencing solder bursting in one of our smt reflow lines. Burst as small as 5mil diameter are messing gold fingers of the pcbs. Anybody who have experienced same problem? Would appreciate any suggestion.

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Solder Bursting | 14 February, 2004

What are your preheat rates? Try a slower ramp. A typical insurance policy is to kapton tape the gold card edge.

If your problem persists, try baking the boards to drive the moisture out.

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Solder Bursting | 16 February, 2004


What is your RH in the SMT area? Is a different paste used on this product than on the other lines. Could your paste be absorbing humidity from the air and discharging the moisture at reflow? This will cuase what you are describing.

Good Luck


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Solder Bursting | 18 February, 2004

Sometimes this is related to oxidized paste or paste that has sat onthe board too long before reflow. However most likely this is related to your reflow process. either too slow or too fast of a reflow ramp rate. Heating up an assembly too quickly willnot allow the volatiles in the paste to be driven off before paste becomes molten. thus the splatter.

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Solder Bursting | 18 February, 2004


Thanks for all your inputs. I have met with our smt staff and scheduled an evaluation by early next week based on your suggestions. I'll be happy to relay positive feedback afterwards. To be more detailed, here are our set-ups as you have asked:

Preheat Rate : 1.5degC/sec RH : Specs - 30to65% , ave. actual reading - 50% Temp. Setting : 64degF to 77degF , ave. actual reading - 69degF

More Power!


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