On Tue, 28 Apr 2015 17:48:18 -0700, mike wrote:

For today's fix, I took the hot air rework pencil out to the
garage. Heated the seam with 360C air and pinched it together with
tweezers to melt it all together.
Doesn't look pretty, but I can't break it apart, so guess it works.

Yep. It's called "plastic welding". My hot air SMD desoldering tool
(Saeke 852D+) produces far too wide a heat affected zone with the
standard tips. For big pieces of plastic, such as case parts, it
works, but not for small and thin parts like battery and wall wart
cases. I also like to work from the back of the plastic part, so as
not to make the cosmetic side look bad. That's impossible with
batteries and wall warts. I get best results with a tiny tip, high
heat, very low air flow, and working fast. As always, there are
YouTube videos on plastic welding.

This might offer a clue:
http://www.harborfreight.com/welding/plastic-welders.html
Note the tiny tip and low air flow.

I guess I should mention that I tried a narrow nozzle on my heat gun
that is normally used for shrink tube. Since I had little control
over temperature or air flow, my first attempt blew a hole through the
plastic parts. Not recommended.

I forgot to mumble something about the horrors of polyurethane
welding. Unlike ABS and PVC, polyurethane is a themosetting plastic,
instead of thermoplastic. That means it burns when heated, instead of
melting. The fix is to not let oxygen anywhere near the joint by
using nitrogen to displace the oxygen. I modified my hot air SMD
rework tool to work this way and found that my reflow soldering
somewhat improved. See Item #7 at:
http://www.hakkousa.com/leadfree.asp
Typical automotive plastic welder that uses nitrogen:
http://prospot.com/products/np-3/ (See speed welding tip)
You probably won't run into the thermosetting problem, or need
nitrogen, but it's a good thing to know.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558