On 31 Jan 2006 00:34:40 -0800, "larry moe 'n curly"
wrote:


K `Sleep wrote:

I don't think that there are too many places hat repair circuit boards that
have been "chomped off", most would just replace the board.

For some reason, I once received a flyer from a company that claimed it
could repair all kinds of extensive damage, including plated-through
holes in multilayer boards and sections that had cracked or were lost.
The before & after pictures they showed made the boards look like new
again.

I have had some luck with 2 part marine epoxy, that can be purchased from
Home Depot. You will still need to be a bit conservative with the heat of
the soldering though.

How many seconds can it stand a soldering iron. I did what I thought
was a nice repair, but the instant the iron touched the copper, the
glue turned to water.

I use crazy glue (cyanoacylate).
Don't try and solder the copper back together, too much heat is
required and will damage the board itself.
Use strands of wire and jumper across the cracked sections.
I use strands from some 12 gauge stainless steel wire that I have,
though regular copper will do.
Use a dremel and a very fine drill bit to drill holes in the copper
plating on either side of the crack and use a low watt gun(25-30
watts) and a good grade of flux. I also use a pure silver solder, it
seems to melt a bit easier and grabs much better and faster.
Can be gotten in the plumbing section of most hardware stores and at
jewelery supply shops.
Usually two or three strands of the stainless wire are sufficient to
restore conductivity.
On finer areas of copper circuit I usually use an xacto and "rough" up
the surface so as to get a better grip for the solder.( on the narrow
strip patterns on the board that are too fine to allow for drilling.)
Alway scrape lightly and in a single direction, i.e. in the direction
of the crack. So as not to pull up the copper plating.
If you wind up with an excessive nmber of jumper wires in close
proximity and are worried about arcing or cross shorting use either
liquid silicone or hot glue on the jumpers as an insulator.
Most patches will look like something doctor Frankenstein concocted
but will restore the board to functional use.
I've restored several audio power amp boards in this fashion and all
are still going strong.