Electronics Forum | Thu Nov 01 17:40:52 EST 2001 | davef
Listen to Wolfgang. Your dull solder connection is a process indicator. Some 63Sn / Au solder connections look grainy, depending on how your process them and the materials involved. Gold dissolving in tin forms an intermetallic compound [AuSn4] th
Electronics Forum | Fri Jun 25 15:48:55 EDT 2004 | tcp
The potting definitely is a factor in fracturing the grainy joints, but does not seem to damage a "good" solder joint.
Technical Library | 2007-08-16 13:34:31.0
While experienced inspectors may be able to determine the aesthetic differences between a lead-free PCB assembly and a tin-lead version, one cannot rely on the "experienced eye". "Less wetting out to the pad edges" (Figure A) and "graininess and lack of shininess of the solder joint" (Figure B) are typical comments about some lead-free solder joints. However, in cases where a Nitrogen atmosphere was present during the reflow of the solder joint (Figure C), there will be little visual differences between the lead free alloys and their tin-lead counterparts.
| http://etasmt.com/cc?ID=te_news_bulletin,23576&url=_print
. Dull or grainy joints are not a big concern – the grain structure will grow in a joint over time anyway. But having a dull joint is giving this eventuality a “ head start
Blackfox Training Institute, LLC | https://www.blackfox.com/blog/guide-to-a-successful-lead-free-soldering/
. How to prevent potential defects surrounding the use of lead-free solder? Always try to maintain the right tip temperature. When the tip temperature is too high, it can result in grainy joints
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