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HAVING PROBLEMS W/ PARTS MOVING AT REFLOW

TONY

#28164

HAVING PROBLEMS W/ PARTS MOVING AT REFLOW | 21 April, 2004

I am having problems with one certain board that is gold immersion. I know it is not oven problems or part problems because it is various parts that are moving during reflow. Also I have not had problems with any other boards going through the same reflow oven. When the boards come out of the oven the pads look very wet from flux. I assume the masking on the boards was not cured all the way, but not sure? What is an easy way to test the boards? Any ideas are well appreciated.

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#28169

HAVING PROBLEMS W/ PARTS MOVING AT REFLOW | 21 April, 2004

Please help us understand your situation better. * How do �Having Problems W/ Parts Moving At Reflow� and �When the boards come out of the oven the pads look very wet from flux� relate to one another? * Tell us about solder, flux, reflow profile, and solder paste control methods. * When you say, �various parts that are moving during reflow�; what do you mean [eg, �specific parts that move on this board vary between boards�, �different part numbers on the board are affect by this movement phenomenon�, er what?] * When you say, �I have not had problems with any other boards going through the same reflow oven�; what are the differences [eg, pad solderability protection, fabricator, construction, laminate material, etc.] between this board and other boards that you run through this oven? * Have you checked the adjustment of the mechanicals [eg, fans, conveyor drive, belt or chain vibration etc.] in your oven? [We know you�ve excluded the oven, but something could be on the hairy edge, so that it affects this board, but not the others.]

On your concern about poor solder mask cure, testing of cure involves some pretty nasty chemicals or equipment that most assemblers don�t have in-house [search the fine SMTnet Archives for discussion]. So, either your fabricator or an outside laboratory is a good place to start. Pencil hardness testing could help here too. It should be 6H to 9H, depending on the mask used. Check IPC-SM-840 for solder mask requirements.

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