Electronics Forum | Wed Aug 23 09:09:43 EDT 2000 | Dave F
Dr. Lee: Some say flux lowers the surface tension of solder. Others argue against that point. What is the flux mechanism that lets solder move more freely?
Electronics Forum | Wed Aug 23 09:05:38 EDT 2000 | Dave F
Dr. Lee: In using environmental screening tests to assess solder joint reliability, what are the effects that make low temperature vibration effective in screening of poorly wetted solder connections? What temperature and vibration profile are effe
Electronics Forum | Thu Aug 24 13:38:23 EDT 2000 | Dave F
It seems that sceening at -20�C and using a vibration profile similar to the one you mentioned does a good job of high-lighting defective solder connections on assembled boards, but not affecting good connections. Why is this happening? In there a
Electronics Forum | Wed Aug 23 08:50:04 EDT 2000 | Dave F
Dr. Lee: We had a discussion on the forum recently and I wanted to get your input. What is the best method(s) for elimating (reducing) no-clean solder paste flux from splattering on gold interconnect fingers on a PCA?
Electronics Forum | Thu Aug 24 13:04:28 EDT 2000 | Dave F
How does flux selection fit into the mix of factors affecting splattering? Do various flux formulations splatter more than others?
Electronics Forum | Thu Aug 24 13:09:30 EDT 2000 | Dr. Ning-Cheng Lee
Yes, a flux with a fast wetting rate will be more prone to have spattering. Fluxes with high boiling point solvents are also more prone to have spattering, if the same flux is fast in wetting rate.
Electronics Forum | Thu Aug 24 13:25:01 EDT 2000 | Dave F
What factors in the manufacturers' description of a paste properties give clues to the wetting rate and boiling point of solvents of fluxes?
Electronics Forum | Thu Aug 24 13:36:07 EDT 2000 | Dr. Ning-Cheng Lee
Regarding the boiling point, MSDS may have some infomation reflecting that. Other description such as long stencil life and long tack time may also reflect. Wetting rate typically is not stated in product data sheet. You will need to determine it y
Electronics Forum | Wed Aug 23 08:05:50 EDT 2000 | Eugene Smelik
Dr. Lee: I have read that fillet lifting can be exacerbated by certain types of Pb-free solder. Can you explain which alloys cause this and why? Thanks! Gene Smelik Cookson Performance Solutions
Electronics Forum | Tue Aug 22 11:29:45 EDT 2000 | �ngelo Marques
Hello, Dr. Ning-Cheng Lee The melting point of solder PB-Free its to higher do you now the lower temperature of an PB-Free and its constitution. Its true if the solder paste have in its constitution a Bismut component the melting point its lower?
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