Ed B wrote:
wrote:

I took a knife to my laptop and cut several circuits on my laptop's
motherboard for reasons which will not be stated. I now want to fix it
up, but I don't know where to start. What materials do I need, and how
would I go about fixing these circuits. I know exactly where I made my
cuts, and I was thinking I could take some copper wire or something and
lay it down, maybe solder it on? But, I don't know if this is the best
way. Thank you for your time and interest.


If you did not violate the integrity of the pre-preg dielectric material
(this is the material the the copper is etched onto) to the inner
layers, then chances are that it is repairable.

Gluing wires down and trying to solder them is one idea but this is not
structurally sound because theses traces are very fragile. You would
probably create another stress point along the trace and then it would
break there. This is almost next to impossible to do.

If you can follow the trace from both ends and find vias (these are
holes that transition the circuit from one layer to another) you could
attach a wire to these vias and bridge the cut. That might work.
However, you need really thin wire to do this (30 AWG or smaller)

Either method you will need:

A microscope, conductive epoxy, solder mask, an exacto knife and a
steady hand.
Links to these products:
http://www.mgchemicals.com/products/8331.html
http://www.grainger.com/Grainger/wwg...mId=1611780257


This is my preferred method.

First, carefully scrape back the existing solder mask (the green coating
on the board usually but can be some other color) of the existing
circuit trace to expose some good copper, and also the around affected
area where the epoxy will be applied. Be careful not to cut anymore
traces as they are probably bunched tightly together.
Clean with denatured alcohol. Let dry.
Place a small bead of the epoxy using the supplied syringe to bridge the
gap of the cut.
Let dry, then apply the solder mask

This is a tough job and chances are it might not work. You have alot of
variables against you to start.
I have done this before on other types of cards but I had much thicker
traces to deal with. For me, this has worked on 8 mil traces and
larger. Circuit traces on a mobo are typically 4 mils or less, that's
0.004"
Good luck

Ed B


Wirewrap wire work pretty good for making repairs. (Do they still sell
that stuff?)

Bob