Hey Ed,
Haven't run across that problem (yet), and don't really know how to
clean that. But I did run across another brand of spacers that I didn't
know about before that's made of different material than what Bivar
dissolvable spacers are made of...aren't bivar spacers made of some sort
of sugar ?
http://www.multi-seals.com/washawayspacers.php
They're made of something called Polyvinylpyrrolidone, and contain no
ionizable material, salts, sugars, metals, or soaps, and they are
non-corrosive, non-conductive, and non-toxic.
I just found them in a search today. I'm getting a sample pack of them
sent to me check them out myself, you might check them out too if you've
never tried them.
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ed Popielarski
Sent: Thursday, October 10, 2013 2:31 PM
To: [log in to unmask]
Subject: [TN] Charred dissopad residue
Hi all,
Had an odd problem today.
We have built many of these assemblies with tin/lead solder but just now
switched to lead free solder (higher temperature).
The "Dissopad" contacting the PCB (at a via) liquefied, spread and
charred. The residue is very difficult to remove, especially a concern
since it is under components and could be "conductive". (pix available
on request)
We tried cleaning this with isopropyl alcohol and it didn't seem to
dissolve the charred residue at all.
I soaked one PCB in 140F DI water for 30 min. and re-cleaned in the
aqueous cleaner. It did seem to remove the heavier residue, but there
remains a film and smaller clumps on the board surface.
Any suggestions would be appreciated!
Ed Popielarski
Engineering Manager
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