Electronics Forum | Fri Dec 16 08:00:26 EST 2005 | jax
What you are most likely dealing with: Insufficient Pure Sn layer ( multiple causes ) Because elevated temperatures accelerate the diffusion process, the thickness of the Pure Sn layer will reduce during every thermal cycle... ( bakeing PCBs, S
Electronics Forum | Thu Aug 20 07:46:55 EDT 2009 | sergey2007
This is a picture of the board without components.
Electronics Forum | Tue Aug 18 16:32:25 EDT 2009 | ldavis
Sergey, Try increasing the cool down time if that is a recipe option. We have witnessed the same effect on components that have rather slow cool down rates and were able to eliminate the problem by extending the cooling time.
Electronics Forum | Wed Aug 19 16:07:58 EDT 2009 | davef
We don't know dip about vapor phase soldering, but we can't help but wonder how well the leads of the component match with the pads on the board.
Electronics Forum | Thu Aug 20 04:37:03 EDT 2009 | sergey2007
Hi, I also paid attention on the solder balls.. I thought it was because of the pop-corning, but the customer told me the component was not damaged.. Regarding the bunch of tented vias, I need to ask the customer about that. Probably, they have unpo
Electronics Forum | Tue Aug 18 02:10:14 EDT 2009 | sergey2007
Hello, I have a customer who recentely installed a vapor phase soldering system. Everything goes pretty well, but from time to time the customer has the same problem with the soldering: one of the components on PCB (usually, it's a QFP package) is ro
Electronics Forum | Tue Aug 18 17:40:52 EDT 2009 | jlawson
Is the mechanics ok with the raising and lowering into the vapour ie no small movements that could be moving the part ? Most Vapour Machines have a lower and raise mechanisim so movemnt of parts can happen if not smooth, especially when coming out o
Electronics Forum | Thu Aug 20 19:07:29 EDT 2009 | smt_guy
reduce the stencil aperture to prevent tombstoning in vapor phase process. from my experience a 6 mil thick must be at least between 20 to 30 % aperture reduction for 0805's and below. cheers!
Electronics Forum | Wed Aug 19 01:00:13 EDT 2009 | sergey2007
Hi! Thanks to everyone! Josh, I don't think it could be something wrong with the mechanics, as just one component was rotated. Anyway, we will check the mechanical parts of the oven. LarryD, thank you for the advice. But what is the physics of the
Electronics Forum | Tue Aug 25 10:38:03 EDT 2009 | grahamcooper22
Hi Sergey, Do you know the Moisture Sensitivity Level of the component ? This is normally recorded on the DRY PACK that the device comes in. It is not unusual for a device to POP CORN and still work in test. It depends how much damage there is to th
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