keyboard plastic PCB repair?

[frank]

Hello folks,

did anyone suceeded in repairing traces on that old plastic sheet printed
circuits keyboards? Some traces are interrupted and it's impossible to
solder on that kind of plastic/trace combination. I've had some success
on plastic substrate when the tracks were copper strips of sufficient
thickness, but in this case they looks like black conductive material and
the plastic substrate is so thin that any tip at a useful temperature for
soldering instantly makes a hole.
I've been thinking about conductive glue, but it might not stick or make
a good contact. So if anyone already had experience (positive or negative)
is very welcome.
It's a 30 years old mitsumy custom keyboard, so not replaceable with something
modern.
Thanks
Frank

 

On Wednesday, March 8, 2017 at 12:56:22 PM UTC-5, frank wrote:

Hello folks,

did anyone suceeded in repairing traces on that old plastic sheet printed
circuits keyboards? Some traces are interrupted and it's impossible to
solder on that kind of plastic/trace combination. I've had some success
on plastic substrate when the tracks were copper strips of sufficient
thickness, but in this case they looks like black conductive material and
the plastic substrate is so thin that any tip at a useful temperature for
soldering instantly makes a hole.
I've been thinking about conductive glue, but it might not stick or make
a good contact. So if anyone already had experience (positive or negative)
is very welcome.
It's a 30 years old mitsumy custom keyboard, so not replaceable with something
modern.
Thanks
Frank

Get a Circuit Writer pen from Caig labs. I've tried using black conductive paint from several sources and it's not conductive enough.

 

[pfjw@aol.com]

At +/- $12.50 per pen, it is going to be cheaper than a new board in very nearly every case.

Peter Wieck
Melrose Park, PA

 

[pfjw@aol.com]

On Wednesday, March 8, 2017 at 2:47:19 PM UTC-5, N_Cook wrote:

I've used "Tempest-proof" RFI blocking, nickel spray .
After shaking the aerosol can , squirt some into a small container and
paint on with a toothpick, good low ohmage.

True, but nickel is very hard to solder. Silver is not. The former when soldering is necessary, the latter when not.

Peter Wieck
Melrose Park, PA

 

[Look165]

Try this :

https://www.chemtronics.com/c-275-circuitworks-conductive-pens-and-inks.aspx.

It is magic.

frank a écrit :

Hello folks,

did anyone suceeded in repairing traces on that old plastic sheet printed
circuits keyboards? Some traces are interrupted and it's impossible to
solder on that kind of plastic/trace combination. I've had some success
on plastic substrate when the tracks were copper strips of sufficient
thickness, but in this case they looks like black conductive material and
the plastic substrate is so thin that any tip at a useful temperature for
soldering instantly makes a hole.
I've been thinking about conductive glue, but it might not stick or make
a good contact. So if anyone already had experience (positive or negative)
is very welcome.
It's a 30 years old mitsumy custom keyboard, so not replaceable with something
modern.
Thanks
Frank

 

[N_Cook]

On 08/03/2017 17:53, frank wrote:

Hello folks,

did anyone suceeded in repairing traces on that old plastic sheet printed
circuits keyboards? Some traces are interrupted and it's impossible to
solder on that kind of plastic/trace combination. I've had some success
on plastic substrate when the tracks were copper strips of sufficient
thickness, but in this case they looks like black conductive material and
the plastic substrate is so thin that any tip at a useful temperature for
soldering instantly makes a hole.
I've been thinking about conductive glue, but it might not stick or make
a good contact. So if anyone already had experience (positive or negative)
is very welcome.
It's a 30 years old mitsumy custom keyboard, so not replaceable with something
modern.
Thanks
Frank

I've used "Tempest-proof" RFI blocking, nickel spray .
After shaking the aerosol can , squirt some into a small container and
paint on with a toothpick, good low ohmage

 

On Wed, 8 Mar 2017 17:53:31 -0000 (UTC), frank <frank@invalid.net>
wrote:

Hello folks,

did anyone suceeded in repairing traces on that old plastic sheet printed
circuits keyboards? Some traces are interrupted and it's impossible to
solder on that kind of plastic/trace combination. I've had some success
on plastic substrate when the tracks were copper strips of sufficient
thickness, but in this case they looks like black conductive material and
the plastic substrate is so thin that any tip at a useful temperature for
soldering instantly makes a hole.
I've been thinking about conductive glue, but it might not stick or make
a good contact. So if anyone already had experience (positive or negative)
is very welcome.
It's a 30 years old mitsumy custom keyboard, so not replaceable with something
modern.
Thanks
Frank

I have no idea what that keyboard looks like, but all keyboards can be
taken apart and the cord is plugged into the board inside of it. Maybe
you can use your old cord on a modern keyboard. Just a thought!

 

[Look165]

The chemtronic CW2200 is a very good conductor and you can ssolder on it.

frank a écrit :

Hello folks,

did anyone suceeded in repairing traces on that old plastic sheet printed
circuits keyboards? Some traces are interrupted and it's impossible to
solder on that kind of plastic/trace combination. I've had some success
on plastic substrate when the tracks were copper strips of sufficient
thickness, but in this case they looks like black conductive material and
the plastic substrate is so thin that any tip at a useful temperature for
soldering instantly makes a hole.
I've been thinking about conductive glue, but it might not stick or make
a good contact. So if anyone already had experience (positive or negative)
is very welcome.
It's a 30 years old mitsumy custom keyboard, so not replaceable with something
modern.
Thanks
Frank