Electronics Forum | Thu Feb 16 12:41:50 EST 2006 | fredericksr
Hey folks, I was interested in any information that you might have on tombstone reduction when using a lead free solder and profile. Thanks for any input that you may have! -Russ #x
Electronics Forum | Fri Feb 17 09:02:21 EST 2006 | russ
proper pad geometries, accurate placement, and good reflow profile. Are you having problems right now?
Electronics Forum | Fri Feb 17 11:01:47 EST 2006 | amol_kane
with lead-free solders, one would expect to find less instances of tombstoning. this is because SAC alloys are not eutectic and melt over a range of temp (usually 217-220 deg C) instead of at a single temperature. therefore the forces due to solder s
Electronics Forum | Fri Mar 06 16:17:38 EST 2009 | aj
whats your board finish?
Electronics Forum | Thu Mar 05 11:53:09 EST 2009 | dcell_1t
Hello to all. for certain time, we have been struggling with some issues on a PCB where have tombstoning on 0402 components (due to pad design) and dewetting in qfp256 0.5 mil pitch (discussed on another threads on this forum) component, we have pro
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 Mar 06 02:47:15 EST 2009 | lococost
Have you tried higher peaktemp? I saw the QFP is sn90pb10, This has a liquidus of 268 - 302 C. A good paste should be able to handle 230C (or more), of course you would need to check your other components peak temp.
Electronics Forum | Fri Mar 06 11:01:53 EST 2009 | dyoungquist
I have attached a pdf version of an article that explains the basics of a nitrogen atmosphere when soldering. It gives some basic guidlines as to when one may want to use nitrogen and what it can and can not accomplish. FYI- I did not write that ar
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%
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