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Home > Archive > Electrical Engineering > April 2007 > Repairing mylar cable?
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Repairing mylar cable?
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| John E. 2007-04-09, 1:25 pm |
| Cable was damaged by melting several (6) traces worth of conductors. It's
part of an expensive controller assembly for which no individual replacement
parts such as this are available. Terminated end is under membrane switch
panel which is affixed to the front of the controller. Disassembly to reach
the other end of the cable would be near-destructive.
So I'm resolved to fix it. The best approach I can think of is to scrape away
the light protective coating over the conductors (which aren't copper PC, but
some painted-on conductive substance) but not scrape too deeply (I've found
by experimenting that this is Not Good )c: ) and affix 30 ga wires via
conductive epoxy, bridging the damage.
I dread this approach because of the fine pitch of the conductors, and not
knowing until I've finished each patch whether 1) there remains enough
conductor to patch and 2) the epoxy "took".
There is about 1 inch undamaged conductor on either side of the damage to
effect a connection, so if any one attempt at bridging a conductor fails I
can attempt another, if need be.
It's going to be rough going, I fear.
Any other suggestions? Maybe find source for this type of cable and graft it
to the existing one?
Sources for these cables?
Thanks,
--
John English
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| bill.sloman@ieee.org 2007-04-09, 1:25 pm |
| On Apr 9, 5:25 pm, John E. <incogn...@yahoo.com> wrote:
> Cable was damaged by melting several (6) traces worth of conductors. It's
> part of an expensive controller assembly for which no individual replacement
> parts such as this are available. Terminated end is under membrane switch
> panel which is affixed to the front of the controller. Disassembly to reach
> the other end of the cable would be near-destructive.
>
> So I'm resolved to fix it. The best approach I can think of is to scrape away
> the light protective coating over the conductors (which aren't copper PC, but
> some painted-on conductive substance) but not scrape too deeply (I've found
> by experimenting that this is Not Good )c: ) and affix 30 ga wires via
> conductive epoxy, bridging the damage.
>
> I dread this approach because of the fine pitch of the conductors, and not
> knowing until I've finished each patch whether 1) there remains enough
> conductor to patch and 2) the epoxy "took".
>
> There is about 1 inch undamaged conductor on either side of the damage to
> effect a connection, so if any one attempt at bridging a conductor fails I
> can attempt another, if need be.
>
> It's going to be rough going, I fear.
>
> Any other suggestions? Maybe find source for this type of cable and graft it
> to the existing one?
What is the pitch of the conductors?
Printed circuit manufacturers make flexible printed cables - flexies -
which are patterns of copper on a variety of substrates. They are
usually supplied with an insulating layer on both sides of the
conducting traces.
You define where you want the copper with "Gerber plots" in the same
way that you describe a rigid printed circuit board you want
manufactured.
Tell us where you are, and someone may be able to suggest the name of
a supplier in your area.
--
Bill Sloman, Nijmegen
| |
| John Larkin 2007-04-09, 1:25 pm |
| On Mon, 09 Apr 2007 15:25:48 GMT, John E. <incognito@yahoo.com> wrote:
>Cable was damaged by melting several (6) traces worth of conductors. It's
>part of an expensive controller assembly for which no individual replacement
>parts such as this are available. Terminated end is under membrane switch
>panel which is affixed to the front of the controller. Disassembly to reach
>the other end of the cable would be near-destructive.
>
>So I'm resolved to fix it. The best approach I can think of is to scrape away
>the light protective coating over the conductors (which aren't copper PC, but
>some painted-on conductive substance) but not scrape too deeply (I've found
>by experimenting that this is Not Good )c: ) and affix 30 ga wires via
>conductive epoxy, bridging the damage.
>
>I dread this approach because of the fine pitch of the conductors, and not
>knowing until I've finished each patch whether 1) there remains enough
>conductor to patch and 2) the epoxy "took".
>
>There is about 1 inch undamaged conductor on either side of the damage to
>effect a connection, so if any one attempt at bridging a conductor fails I
>can attempt another, if need be.
>
>It's going to be rough going, I fear.
>
>Any other suggestions? Maybe find source for this type of cable and graft it
>to the existing one?
>
>Sources for these cables?
>
>Thanks,
3M makes connectors that pierce such flexprint conductors, with spikes
that fold over and make good contact.
John
| |
| John E. 2007-04-10, 3:25 am |
| > What is the pitch of the conductors?
20 conductor, 1 mm pitch, "painted" conductor (not copper strip).
[...]
> Tell us where you are, and someone may be able to suggest the name of
> a supplier in your area.
SF bay area, N. California, USA.
> Bill Sloman, Nijmegen
Thanks for your suggestions, Bill.
On further examination the "flexie" seems to be contiguous with the membrane
switch backplane; it's one piece, so a replacement doesn't sound likely.
Now, if a means exists for easily (!) and reliably grafting another
20-conductor flexie to the good stub, I'm all ears!
Or... other ideas?
Thanks again,
--
John English
| |
| John E. 2007-04-10, 3:25 am |
| > 3M makes connectors that pierce such flexprint conductors, with spikes
> that fold over and make good contact.
>
> John
I wonder if they make a splice connector that would simply connect two
flexies. Man, that would just save my bucket.
Other possibility with such connectors: crimp on a female flexie connector
and use another flexie to bridge the gap.
Can you recall a trade name? P/N, by chance or by prayer? Source? (c:
Thanks for your assistance, John. It's a glimmer in the dark...
--
John English
| |
| N Cook 2007-04-10, 9:25 am |
| John E. <incognito@yahoo.com> wrote in message
news:0001HW.C23FA9F604788CFAF05096C8@news.sf.sbcglobal.net...
> Cable was damaged by melting several (6) traces worth of conductors. It's
> part of an expensive controller assembly for which no individual
replacement
> parts such as this are available. Terminated end is under membrane switch
> panel which is affixed to the front of the controller. Disassembly to
reach
> the other end of the cable would be near-destructive.
>
> So I'm resolved to fix it. The best approach I can think of is to scrape
away
> the light protective coating over the conductors (which aren't copper PC,
but
> some painted-on conductive substance) but not scrape too deeply (I've
found
> by experimenting that this is Not Good )c: ) and affix 30 ga wires via
> conductive epoxy, bridging the damage.
>
> I dread this approach because of the fine pitch of the conductors, and not
> knowing until I've finished each patch whether 1) there remains enough
> conductor to patch and 2) the epoxy "took".
>
> There is about 1 inch undamaged conductor on either side of the damage to
> effect a connection, so if any one attempt at bridging a conductor fails I
> can attempt another, if need be.
>
> It's going to be rough going, I fear.
>
> Any other suggestions? Maybe find source for this type of cable and graft
it
> to the existing one?
>
> Sources for these cables?
>
> Thanks,
> --
> John English
>
Bare back to conductors , cover whole area with silver loaded paint and when
cured score lines with ruler and scalpel , pairs of close lines and scrape
off the areas between lines with a slightly blunt needle against ruler.
You need a magnifier lamp and check with a DVM before and after the process.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
| |
| John E. 2007-04-10, 1:25 pm |
| > Bare back to conductors, cover whole area with silver loaded paint and when
> cured score lines with ruler and scalpel, pairs of close lines and scrape
> off the areas between lines with a slightly blunt needle against ruler.
> You need a magnifier lamp and check with a DVM before and after the process.
Not quite clear to me... does this involve any new flexie material? Or just
paint? Is paint expected to bridge a gap in the flexie?
This seems a good way to repair breaks in conductive traces, but a damaged
flexie...?
If you could explain in a bit more detail...
Thanks,
--
John English
| |
| N Cook 2007-04-10, 1:25 pm |
| John E. <incognito@yahoo.com> wrote in message
news:0001HW.C24108BB04872046F04076C8@news.sf.sbcglobal.net...
when[color=darkred]
scrape[color=darkred]
process.[color=darkred]
>
> Not quite clear to me... does this involve any new flexie material? Or
just
> paint? Is paint expected to bridge a gap in the flexie?
>
> This seems a good way to repair breaks in conductive traces, but a damaged
> flexie...?
>
> If you could explain in a bit more detail...
>
> Thanks,
> --
> John English
>
does it flex in use or just to assemble/disassemble ?
| |
| John E. 2007-04-10, 1:25 pm |
| > does it flex in use or just to assemble/disassemble ?
No movement in use. It is just a means of getting membrane switch inputs to
the PCB.
Thanks,
--
John English
| |
| John Fields 2007-04-10, 5:25 pm |
| On Tue, 10 Apr 2007 18:15:35 GMT, John E. <incognito@yahoo.com>
wrote:
>
>No movement in use. It is just a means of getting membrane switch inputs to
>the PCB.
See my post to seb.
--
JF
| |
| PeterD 2007-04-10, 5:25 pm |
| On Tue, 10 Apr 2007 18:15:35 GMT, John E. <incognito@yahoo.com> wrote:
>
>No movement in use. It is just a means of getting membrane switch inputs to
>the PCB.
>
>Thanks,
John,
I've done repairs such as you describe. A PITA, but it worked when I
was done. I figured it would last a few months and that was maybe four
years ago. It still works, and sees service in a rugged environment
with lot's of abuse!
In my case I used a technique such as your initial idea of the
conductive epoxy and 30 gauge wires...
| |
| John E. 2007-04-11, 3:25 am |
| > In my case I used a technique such as your initial idea of the
> conductive epoxy and 30 gauge wires...
Thanks, Peter. If I can't find a connector-cable-connector solution to my
problem, it's nice to know that someone has blazed this particular trail with
these particular tools before.
Thanks again,
--
John English
| |
| John Fields 2007-04-11, 9:25 am |
| On Tue, 10 Apr 2007 15:06:10 -0500, John Fields
<jfields@austininstruments.com> wrote:
>On Tue, 10 Apr 2007 18:15:35 GMT, John E. <incognito@yahoo.com>
>wrote:
>
>
>See my post to seb.
---
Which one? ;)
Check this out:
https://portal.fciconnect.com/porta...tx_pages_list=%
7CPRODUCT_TYPE&ctx_urlparams_list=%7CcategoryNodeName%3DFLEX
If the link wraps, go here:
https://portal.fciconnect.com/porta...TAL&language=EN
and navigate the menu.
I think AMP (Tyco) also makes essentially the same thing.
I think you'll have trouble finding mating males, but if you're
lucky and the conductor pitch is right, (I'm guessing 0.1")
you'll be able to use two females and insert a male-male
header between them.
--
JF
| |
| Tam/WB2TT 2007-04-11, 1:25 pm |
|
"John E." <incognito@yahoo.com> wrote in message
news:0001HW.C23FA9F604788CFAF05096C8@news.sf.sbcglobal.net...
> Cable was damaged by melting several (6) traces worth of conductors. It's
> part of an expensive controller assembly for which no individual
> replacement
> parts such as this are available. Terminated end is under membrane switch
> panel which is affixed to the front of the controller. Disassembly to
> reach
> the other end of the cable would be near-destructive.
>
> So I'm resolved to fix it. The best approach I can think of is to scrape
> away
> the light protective coating over the conductors (which aren't copper PC,
> but
> some painted-on conductive substance) but not scrape too deeply (I've
> found
> by experimenting that this is Not Good )c: ) and affix 30 ga wires via
> conductive epoxy, bridging the damage.
>
> I dread this approach because of the fine pitch of the conductors, and not
> knowing until I've finished each patch whether 1) there remains enough
> conductor to patch and 2) the epoxy "took".
>
> There is about 1 inch undamaged conductor on either side of the damage to
> effect a connection, so if any one attempt at bridging a conductor fails I
> can attempt another, if need be.
>
> It's going to be rough going, I fear.
>
> Any other suggestions? Maybe find source for this type of cable and graft
> it
> to the existing one?
>
> Sources for these cables?
>
> Thanks,
> --
> John English
I can't quite visualize your cable, but can you cut it at the bad spot, and
clamp it between two pieces of PC board, where one or both PC boards have
traces on them that line up with your conductors? The connection would be
made by compression.
Tam
| |
| John E. 2007-04-11, 5:25 pm |
| > I can't quite visualize your cable,
It's just a single-sided, translucent mylar flex cable with 20 "printed"
conductors on 1 mm centers.
> but can you cut it at the bad spot, and
> clamp it between two pieces of PC board, where one or both PC boards have
> traces on them that line up with your conductors? The connection would be
> made by compression.
The success of this would depend on how well I could scrape away the
protective layer above the "painted" conductors without removing the
conductive material. I'm not so confident to be able to do that 40 times
reliably such that the resultant bare conductors would all line up nicely
with the PC traces.
--
John English
| |
|
| On 2007-04-10, John E <incognito@yahoo.com> wrote:
>
> Not quite clear to me... does this involve any new flexie material? Or just
> paint? Is paint expected to bridge a gap in the flexie?
>
> This seems a good way to repair breaks in conductive traces, but a damaged
> flexie...?
if there's a gap glue a bridge behind it (you'll have to find an adhesive
that sticks to it and goes hard, )
--
Bye.
Jasen
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