"rangerssuck" wrote in message
...
On Friday, June 17, 2016 at 5:49:22 PM UTC-4, Jim Wilkins wrote:
"Jon Elson" wrote in message
...
CARLOS REIS wrote:

replying to Jon Elson, CARLOS REIS wrote:
Thanks Jon

I will try to rewire one of this days

OK, if I had a complete choice, I'd do this under a stereo zoom
microscope,
and use fine tweezers. I do micro soldering all the time anyway,
but this
was something that really tested my skills.

Jon

Conductive epoxy is good for really fine work. I repaired a broken
1
mil x 5 mil bonding ribbon on a laser diode die with it.

--jsw

I've also done lots of ridiculously small soldering with the aid of
a stereo zoo scope, but I've never used conductive epoxy.

Properly cleaned and fluxed, solder will (usually) go where it's
supposed to go and (usually) stay out of where it's not supposed to
go. How do you handle this with epoxy? If you accidentally get some
where it's not supposed to go, can you clean it off?

I could certainly see using conductive epoxy for repairing Kapton
flat cables. That stuff is really hard to solder without melting
lots of plastic.

I used conductive epoxy only where I had to. Gold bonding ribbon
dissolves instantly in solder. I soldered temporary isolating cuts in
not-much-larger 6 mil copper traces. It's easier if the cut is skewed
so the beveled ends overlap.

The bonding ribbons were fairly long arches from copper pads to the
laser diode die which was mounted on a diamond substrate. Apparently
the tech at the first government lab that had the project was
incapable of such delicate work, so Mitre got it and I patched his
mistakes. They knew I could stack up 3D assemblies of 0201 resistor
chips. My demo was to join 0.015" solder into linked rings.

--jsw