repairing traces on PCB
 

Liquid silver is too expensive, is there any other way of repairing
traces on PCB?
Actually, I need to repair graphite traces on keyboard connector.
Using spray GRAPHITE 33 totally messed everything.

On Mon, 23 Aug 2004 12:29:53 GMT, Ross Herbert
wrote:

On Mon, 23 Aug 2004 14:05:13 +0200, Orange wrote:

|Liquid silver is too expensive, is there any other way of repairing
|traces on PCB?
|Actually, I need to repair graphite traces on keyboard connector.
|Using spray GRAPHITE 33 totally messed everything.

I haven't had any luck repairing flexible pcb traces. I tried silver
loaded epoxy but like you I found it is not easy when traces are close
together. If the keyboard is for a PC then it only costs ( $5 or
free) to replace the keyboard. That always works effectively.
I see.. thanks Ross.
This part isnt so flexible; its the tip of connector that goes into
PCB connector. It was worn out from frequent replacing. It seems that
I've completely destroyed it with that graphite spray (different type
of graphite?)
Its an Amiga 500.
I know the whole of it costs 5 to 10 $ , but its my first Amiga..
--
The Only Way Is Up

Orange wrote in message . ..
Liquid silver is too expensive, is there any other way of repairing
traces on PCB?
Actually, I need to repair graphite traces on keyboard connector.
Using spray GRAPHITE 33 totally messed everything.

Tried very small jumper wires?

Orange wrote:

Liquid silver is too expensive, is there any other way of repairing
traces on PCB?

Conductive paint isn't _that_ expensive ... Presumably you don't need
much.

Even an auto supply store should have something suitable -- they need
it to repair the traces in rear window defoggers.

Actually, I need to repair graphite traces on keyboard connector.
Using spray GRAPHITE 33 totally messed everything.


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

On 23 Aug 2004 13:30:56 -0700, (Brett) wrote:

Orange wrote in message . ..
Liquid silver is too expensive, is there any other way of repairing
traces on PCB?
Actually, I need to repair graphite traces on keyboard connector.
Using spray GRAPHITE 33 totally messed everything.

Tried very small jumper wires?
nope, they are not suitable.
Guess I'll have to buy that "back car window heater repair liquid".
Why don't they make liquid copper instead of silver?
--
Take what you want and pay for it, says God

"Orange" wrote in message
...
On 23 Aug 2004 13:30:56 -0700, (Brett) wrote:

Orange wrote in message
. ..
Liquid silver is too expensive, is there any other way of repairing
traces on PCB?
Actually, I need to repair graphite traces on keyboard connector.
Using spray GRAPHITE 33 totally messed everything.

Tried very small jumper wires?
nope, they are not suitable.
Guess I'll have to buy that "back car window heater repair liquid".
Why don't they make liquid copper instead of silver?
--
Take what you want and pay for it, says God

There are some pens designed for PC Board Trace repair..... sold by
Electronics Supply Houses. Are they any good? I don't know.. Never used one,
but they're only like $6 or so..... If memory serves me correctly, there are
two types for thickness. One is a thin and one wider. There are also pens
available at about the same cost for "covering" traces, much like the
protective green coating you usually see over the traces.

L.

L. wrote:

"Orange" wrote in message
...

On 23 Aug 2004 13:30:56 -0700, (Brett) wrote:


Orange wrote in message

. ..

Liquid silver is too expensive, is there any other way of repairing
traces on PCB?
Actually, I need to repair graphite traces on keyboard connector.
Using spray GRAPHITE 33 totally messed everything.

Tried very small jumper wires?

nope, they are not suitable.
Guess I'll have to buy that "back car window heater repair liquid".
Why don't they make liquid copper instead of silver?
--
Take what you want and pay for it, says God


There are some pens designed for PC Board Trace repair..... sold by
Electronics Supply Houses. Are they any good? I don't know.. Never used one,
but they're only like $6 or so..... If memory serves me correctly, there are
two types for thickness. One is a thin and one wider. There are also pens
available at about the same cost for "covering" traces, much like the
protective green coating you usually see over the traces.

L.


The pens are ok, but I found them prone to clogging/drying out.
I prefer something I can brush on.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

"Orange" wrote in message
...
On 23 Aug 2004 13:30:56 -0700, (Brett) wrote:

Orange wrote in message
. ..
Liquid silver is too expensive, is there any other way of repairing
traces on PCB?
Actually, I need to repair graphite traces on keyboard connector.
Using spray GRAPHITE 33 totally messed everything.

Tried very small jumper wires?
nope, they are not suitable.
Guess I'll have to buy that "back car window heater repair liquid".
Why don't they make liquid copper instead of silver?


GC Chemicals offers a product called "Nickel Print". It's on the pricey
side nowadays. I've seen it lately at $20 for a 2 oz. bottle. It's
somewhat flexible, though not really intended for flex traces. It comes
with a brush which is far too wide for most uses, but you should be able to
use small art brushes for fine traces. It's fairly thick and you may want
to use masking tape (really narrow drafting tape works) between closely
spaced traces.

I've found that even the finest point conductive ink pens lay down a line
that's too wide for closely-spaced traces. They also crack if flexed much.
For hard (non-flex) PCB traces, I normally just scrape off the bad section,
scrape the solder resist off both ends of the remaining trace and solder a
jumper bridge.

A cheaper (free, in fact) alternative to using paints on flex boards is
simply to make a new end, IF the cable is long enough to allow for this;
some aren't. There will most likely be a second, non-trace layer of the
cable which you'll have to peel back to expose the underlying traces for the
next step. Do this before you do any cutting, as you'll need the original
end for gripping. The glue is usually pretty sticky, so don't just rip it
off in haste -- you can and will pull off traces if you aren't careful.
Next, cut off an equal amount of this non-trace layer as was absent on the
original cable end. Now that you have twice the length of non-trace layer
gone, you can cut off the original, damaged end with scissors. Cut off only
the bad portion of the plated end and no higher. Make certain the cut is a
STRAIGHT 90 degrees. Next, very gently clean the tacky glue off the new end
to expose the metal traces. You can use masking tape for this, but again,
be careful so as not to pull off trace material. I haven't tried using
solvents to remove the glue, but if you use one that isn't too strong, it
might leave the traces intact. You should now have a new end that looks
like the original with the exception of fully-plated traces. I've done this
successfully with numerous flex boards.
However, as a caveat, some are absolutely uncooperative and the traces will
lift with the greatest of ease.

If you're successful with the above method, you can go the extra mile and
replate the traces with a tin plate wash (I use it for protecting home-brew
hard PCB etchings). Also, the original end may have had a stiff plastic
piece to keep the traces from bending/creasing. Unless you add one to your
new end, it will be susceptible to damage from rough handling, so be gentle
when inserting it into the board connector, and don't remove/replace it
repeatedly.

Good luck...