Electronics Forum | Thu Mar 12 06:37:48 EDT 2009 | gregoryyork
I agree you are too cold for the profile get it up to 230C and possibly allow it to dwell a little longer in preheat as opposed to pushing up the reflow zone only. Sn90/Pb10 melts at 220C so 2C hotter than your profile so you are reliant on it alloyi
Electronics Forum | Fri May 06 08:47:05 EDT 2016 | davef
You're correct. This design will have a record amount of 0402 rework for tombstoning and misalignments. Suggest that the pads on each end of all components be the same size in order to balance wetting forces during reflow.
Electronics Forum | Sun Jun 10 11:31:27 EDT 2001 | nifhail
Everybody aware of the tomb-stone problem on 0402 package. I've done everything I could i.e. Profile, placement, 10 Deg placement, stencil design, but still this culprit exist. One things for sure is taht I have a very bad pad size for 0402 ( 25 mil
Electronics Forum | Sun Jun 10 12:15:37 EDT 2001 | procon
Hello Danial, Leave it up to most to blame the relow oven for their tombstoning problems when in fact it is usually the last to cause it. The biggest culprit of tombstoning is the pad design followed by the print quality. Usually, we find that the p
Electronics Forum | Fri Mar 06 10:50:21 EST 2009 | fountain42
Just my opinion but it look's like your doing a great job. i would try another paste. I'm somewhat lucky that we get to use OA's. If your stuck using the no-cleans they are so tempermental. (The nitrogen is making up for the poor paste) Your de-wetti
Electronics Forum | Fri Mar 06 10:46:35 EST 2009 | davef
First, we agree with Loco that your QFP is nonwetting, rather than dewetting. Your sceen-shots look like ol' timey SnPb paste recipes. Turn-up the heaterometer dial. Second, on nitrogen: * We kinda think your O2 needs to be around 100ppm with 99.99%
Electronics Forum | Mon Jun 18 13:29:34 EDT 2001 | nifhail
What is the recommanded profile for board which consist of 0402 & 0201 comps. to reduce the effect of tomb-stone. Slow ramp rate ? how slow is considered as slow. Soak time 60 or 120 C,at which end should I stick to? what is the best time before reac
Electronics Forum | Fri May 06 08:39:59 EDT 2016 | kahrpr
The first issue I see is that you have a high potential of the 402 tombstoning.
Electronics Forum | Mon Jun 11 21:27:43 EDT 2001 | procon
Way to go CPI! This is a classic example of design. Many people experience this when the have an 0402 close to a QFP or other large components. The pad closest to the larger component will become liquidous later than the pad farthest. Hence, a new t
Electronics Forum | Mon May 09 09:23:45 EDT 2016 | markhoch
I agree with the previous two replies. This is a perfect design....if you're trying to create a graveyard full of tombstones.
