Repairing flat cable

I

isw

Guest
I have a piece of gear that uses a "cable" consisting of printed circuit
traces laminated between two pieces of dark orange plastic (Kynar???).
The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac
 
"isw" <isw@witzend.com> wrote in message
news:isw-0C56E4.21390421122008@[216.168.3.50]...
I have a piece of gear that uses a "cable" consisting of printed circuit
traces laminated between two pieces of dark orange plastic (Kynar???).
The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac
Click to expand...
The plastic can often be 'stripped' with a blunt(ish) curve-bladed scalpel,
scraped across the surface, with it on a flat hard surface such as an old
ceramic tile. Having said that, I have found that the orange ones such as
you used to find in Panasonic answer machines and on Pioneer lasers, are
much more resistant to any kind of stripping, than the white ones. You might
also try ally oxide paper such as you might use for flatting a paint surface
on a car body.

If you manage to get a connection that works ok, I would suggest that it is
then covered with something like a bead of silicone rubber (not the bathroom
sealer type which releases acetic acid as it cures) to help relieve any
stress on the joints, if it is in an application where it flexes in normal
use. If it is not, and you can't get a good connection, you could consider
just hard wiring between the two boards that it connects. If it is socketed
at both ends, replacement flexiprints in many different pitch, ways and
length configurations, are available.

For instance

http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=1573426&keywords=FPC

Arfa
 
isw <isw@witzend.com> wrote in news:isw-0C56E4.21390421122008@
[216.168.3.50]:

I have a piece of gear that uses a "cable" consisting of printed circuit
traces laminated between two pieces of dark orange plastic (Kynar???).
Click to expand...
Low melting point, 117 C. Not likely.
Perhaps PEEK
http://www.sdplastics.com/peek.html

The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?
Click to expand...
Have you tried a razor blade along the surface of the conductor? You may be
able to mechanically split it away from the conductor.

How about grinding it away?

HOT Di-Methyl-Formamide (DMF) will breakdown most plastics but it can be
rough on metals also.
It is also nasty stuff to work with. A well equipped chem lab, Gloves,
hood, face shield, apron.
In the late 60's, when I worked for Sprague, we used to use it to remove
molded epoxy cases from capacitors so we could do fault analysis on the
ceramic chips.






--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
 
isw <isw@witzend.com> wrote in message
news:isw-0C56E4.21390421122008@[216.168.3.50]...
I have a piece of gear that uses a "cable" consisting of printed circuit
traces laminated between two pieces of dark orange plastic (Kynar???).
The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac
Click to expand...
A small cylindrical centrided burr in a dremmel can be useful for stripping
back, surprisingly controllable if you hold it the "right" way round so it
doesn't skud.

Or make up some fine wire plaited braid to replace the whole thing

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
In article <gio7bm$etl$1@news.motzarella.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

isw <isw@witzend.com> wrote in message
news:isw-0C56E4.21390421122008@[216.168.3.50]...
I have a piece of gear that uses a "cable" consisting of printed circuit
traces laminated between two pieces of dark orange plastic (Kynar???).
The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac

A small cylindrical centrided burr in a dremmel can be useful for stripping
back, surprisingly controllable if you hold it the "right" way round so it
doesn't skud.

Or make up some fine wire plaited braid to replace the whole thing
Click to expand...
It's in the lens assembly of a small camera. The cable is less than 0.25
cm wide, and has twelve conductors (I had to use a loupe to count them).
Making a replacement is probably not in the cards.

Isaac
 
In article <Xns9B7C49420328AWQAHBGMXSZHVspammote@130.39.198.139>,
bz <bz+ser@ch100-5.chem.lsu.edu> wrote:

isw <isw@witzend.com> wrote in news:isw-0C56E4.21390421122008@
[216.168.3.50]:

I have a piece of gear that uses a "cable" consisting of printed circuit
traces laminated between two pieces of dark orange plastic (Kynar???).

Low melting point, 117 C. Not likely.
Perhaps PEEK
http://www.sdplastics.com/peek.html

The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Have you tried a razor blade along the surface of the conductor? You may be
able to mechanically split it away from the conductor.
Click to expand...
Tried scraping, sanding, and abrading with a rotary abrasive-fiber wheel
-- everything I tried destroyed the traces...

Isaac
 
"isw" <isw@witzend.com> wrote in message
news:isw-9BC385.20261822122008@[216.168.3.50]...
In article <gio7bm$etl$1@news.motzarella.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

isw <isw@witzend.com> wrote in message
news:isw-0C56E4.21390421122008@[216.168.3.50]...
I have a piece of gear that uses a "cable" consisting of printed
circuit
traces laminated between two pieces of dark orange plastic (Kynar???).
The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron
has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac

A small cylindrical centrided burr in a dremmel can be useful for
stripping
back, surprisingly controllable if you hold it the "right" way round so
it
doesn't skud.

Or make up some fine wire plaited braid to replace the whole thing

It's in the lens assembly of a small camera. The cable is less than 0.25
cm wide, and has twelve conductors (I had to use a loupe to count them).
Making a replacement is probably not in the cards.

Isaac
Click to expand...
Don't you just HATE that sinking feeling you get in your stomach when
something like this happens, especially when it's a customer's unit ... :-(

Long experience of working with flexiprints of all descriptions, leads me to
believe that you are really going to struggle to reliably repair one that
small and fine-pitched. I suppose it would be really silly to ask if there's
any chance at all of getting a replacement ?

Arfa
 
isw wrote:

In article <gio7bm$etl$1@news.motzarella.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

isw <isw@witzend.com> wrote in message
news:isw-0C56E4.21390421122008@[216.168.3.50]...
I have a piece of gear that uses a "cable" consisting of printed
circuit traces laminated between two pieces of dark orange plastic
(Kynar???). The cable was torn in two, and I need to repair it. If I
could remove about an eighth of an inch of the insulation on one side
of each end, I could lap them and solder the conductors. The plastic it
totally resistant to every solvent I have on hand, and a 750F soldering
iron has no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac

A small cylindrical centrided burr in a dremmel can be useful for
stripping back, surprisingly controllable if you hold it the "right" way
round so it doesn't skud.

Or make up some fine wire plaited braid to replace the whole thing

It's in the lens assembly of a small camera. The cable is less than 0.25
cm wide, and has twelve conductors (I had to use a loupe to count them).
Making a replacement is probably not in the cards.

Isaac
Click to expand...
I have seen these replaced by insulated winding wire, e.g. from a relay coil
(maybe 0.002 inch or 50 micron wire). On the other hand I would not do
this for a customer since it may not be reliable in the long term. It
might be worthwhile for fixing you own stuff, however.
Chris
 
In article <2j24l.71396$he4.10494@newsfe22.ams2>,
"Arfa Daily" <arfa.daily@ntlworld.com> wrote:

"isw" <isw@witzend.com> wrote in message
news:isw-9BC385.20261822122008@[216.168.3.50]...
In article <gio7bm$etl$1@news.motzarella.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

isw <isw@witzend.com> wrote in message
news:isw-0C56E4.21390421122008@[216.168.3.50]...
I have a piece of gear that uses a "cable" consisting of printed
circuit
traces laminated between two pieces of dark orange plastic (Kynar???).
The cable was torn in two, and I need to repair it. If I could remove
about an eighth of an inch of the insulation on one side of each end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron
has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac

A small cylindrical centrided burr in a dremmel can be useful for
stripping
back, surprisingly controllable if you hold it the "right" way round so
it
doesn't skud.

Or make up some fine wire plaited braid to replace the whole thing

It's in the lens assembly of a small camera. The cable is less than 0.25
cm wide, and has twelve conductors (I had to use a loupe to count them).
Making a replacement is probably not in the cards.

Isaac

Don't you just HATE that sinking feeling you get in your stomach when
something like this happens, especially when it's a customer's unit ... :-(
Click to expand...
Yeah, and especially because I've fixed two of these cameras previously
(there's a design weakness in a supporting strut inside the lens; a bit
of brass tubing and some epoxy is all it takes). This time, the strut
was fine but somebody had spilled something like orange juice in the
camera, and the moving parts got all gunky and sticky. I think that's
what tore the cable.

Long experience of working with flexiprints of all descriptions, leads me to
believe that you are really going to struggle to reliably repair one that
small and fine-pitched. I suppose it would be really silly to ask if there's
any chance at all of getting a replacement ?
Click to expand...
The only way would be to get a good cable from another scrapped out
camera (which this one now is). The cable terminates on the "sled" that
carries the anti-shake lens, and the driving coils for that are etched
right onto the orange plastic substrate; there are not any "terminals"
to attach replacement wires to...

Isaac
 
"isw" <isw@witzend.com> wrote in message
news:isw-B1031F.21303223122008@[216.168.3.50]...
In article <2j24l.71396$he4.10494@newsfe22.ams2>,
"Arfa Daily" <arfa.daily@ntlworld.com> wrote:

"isw" <isw@witzend.com> wrote in message
news:isw-9BC385.20261822122008@[216.168.3.50]...
In article <gio7bm$etl$1@news.motzarella.org>,
"N_Cook" <diverse@tcp.co.uk> wrote:

isw <isw@witzend.com> wrote in message
news:isw-0C56E4.21390421122008@[216.168.3.50]...
I have a piece of gear that uses a "cable" consisting of printed
circuit
traces laminated between two pieces of dark orange plastic
(Kynar???).
The cable was torn in two, and I need to repair it. If I could
remove
about an eighth of an inch of the insulation on one side of each
end, I
could lap them and solder the conductors. The plastic it totally
resistant to every solvent I have on hand, and a 750F soldering iron
has
no effect.

Does anybody know of a solvent for the plastic, or some other way to
strip the traces?

Isaac

A small cylindrical centrided burr in a dremmel can be useful for
stripping
back, surprisingly controllable if you hold it the "right" way round
so
it
doesn't skud.

Or make up some fine wire plaited braid to replace the whole thing

It's in the lens assembly of a small camera. The cable is less than
0.25
cm wide, and has twelve conductors (I had to use a loupe to count
them).
Making a replacement is probably not in the cards.

Isaac

Don't you just HATE that sinking feeling you get in your stomach when
something like this happens, especially when it's a customer's unit ...
:-(

Yeah, and especially because I've fixed two of these cameras previously
(there's a design weakness in a supporting strut inside the lens; a bit
of brass tubing and some epoxy is all it takes). This time, the strut
was fine but somebody had spilled something like orange juice in the
camera, and the moving parts got all gunky and sticky. I think that's
what tore the cable.

Long experience of working with flexiprints of all descriptions, leads me
to
believe that you are really going to struggle to reliably repair one that
small and fine-pitched. I suppose it would be really silly to ask if
there's
any chance at all of getting a replacement ?

The only way would be to get a good cable from another scrapped out
camera (which this one now is). The cable terminates on the "sled" that
carries the anti-shake lens, and the driving coils for that are etched
right onto the orange plastic substrate; there are not any "terminals"
to attach replacement wires to...

Isaac
Click to expand...
Ah well, some ya win, some ya lose ... At least if the owner has filled the
thing up with juice, there's justification for declaring it BER, and at
least it's not a problem that you have caused whilst repairing some really
simple thing. That one's the killer. When you've fixed the dirty volume
control with a lttle squib of switch cleaner, and then you drop your
screwdriver into the output stage ... >:-\

Have a good 'un

Arfa
 
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