"Ian P" wrote in message
...
After mulling over all the good guidance and advice I recieved in response
to my original posting I decided which method to use and this evening have
successfully repaired the cut tracks.

I went for the soldered wire jumpers over the breaks, straightforward
under normal circumstances but in this case on a small scale. I bridged
four adjacent tracks using wire 0,05mm (2 thou) diameter taken from super
flexible test lead wire. The tracks were were between 0.1 and 0.15mm wide
and the whole repaired area ended up 0.9mm wide and 4mm long.

With the right equipment, microscope etc I can now see that a repair of
this sort could be done fairly easily, I managed with a strong magnifyng
glass that I fixed in place so I had both hands free. After I fixed the
first jumper I improved my technique and was able to work one handed by
using a longer length of jumper held taught exactly in line with the track
by bits of masking tape at either end. Because of its length its really
easy to position the jumper, I also put a little bit of packing under the
ribbon so that it formed a raised surface to keep the wire in contact with
the previously tinned tracks.

I still have to test the repair but mechanically all the joints are sound
and separated from each other so I'm happy.

Many thanks to all that responded.

Ian


Glad you got a fix ! If the flexiprint doesn't have to bend at the point
where you've repaired it - and I assume that it doesn't as you say that you
have put some strengthening behind it - you might want to coat over the
repair with some clear nail laquer, just to add a bit of 'stay still' to the
wires, and offer a bit of physical protection.

Don't know if you might have a need in the future to do any very fine work
like this again, but if you do, a stereo microscope with built in work lamp
is indispensible. You can pick them up quite cheaply on eBay. Mine came from
Farnell when they had them on offer a few years back. It takes a bit of
getting used to soldering under one, as even the finest tipped iron looks
like a wrought iron poker that the local smithy has just turned out, and the
solder looks like a steel ship hawser, but then even very fine tracks look
like roads, so it's all relative ...

Arfa