The problem with ROHS is it seems to be one factor that fosters growth of tin
whiskers and dendrites. Lead in solder prevented that. NASA produced a good
resource paper on the subject titled Basic Information on Tin Whiskers.
Dendrites and tin whiskers are not the same creatures. ScottSent via the
Samsung Galaxy S8+, an AT&T 5G Evolution capable smartphone
-------- Original message --------From: Gary K9GS <k9gs@gjschwartz.com> Date:
3/4/20 20:03 (GMT-05:00) To: rfi@contesting.com Subject: Re: [RFI] LED
streetlights - Lumenistics I work in electronics manufacturing. Lead free
solder for surface mount devices has been commonplace for more than 20
years.It's stable and proven technology. Higher solder temperatures are correct
but nothing more than a different process variable. 73,Gary K9GS--------
Original message --------From: Ken Winterling <wa2lbi@gmail.com> Date: 3/4/20
6:17 PM (GMT-06:00) To: KD7JYK DM09 <kd7jyk@earthlink.net> Cc: Rfi List
<rfi@contesting.com> Subject: Re: [RFI] LED streetlights - Lumenistics I
believe you can thank lead-free solder for many failed joints. It needshigher
heat to melt than the leaded type. I’ve been working on equipmentfor over
fifty years and see more PCB solder joint failures in the recentdecades than
when I was much younger.KenWA2LBIOn Wed, Mar 4, 2020 at 18:20 KD7JYK DM09
<kd7jyk@earthlink.net> wrote:> "I remember years ago when municipalities
replaced incandescent traffic> lights with LED lights to save money. They
discovered that in winter the> snow would cover and block the lights since they
didn’t generate heat> like their predecessors.">> Another issue, both with LED
traffic signals, and automotive lights,> which personally bugs the crap out of
me, is the hot/cold of just the> weather alone causes the solder joints to fail
quickly, and I see lamps> with various blocks, chunks, stripes, et cetera where
a section no> longer illuminates.>> One would have imagined this to be resolved
in initial testing, but I> still see it on a daily basis, after, what, some
thirty years of> technology evolution?>> Kurt> --KenWA2LBISent from one of my
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