In the course of doing some modifications to a very expensive Sony 3 chip HD
camcorder I have accidentally cut through 3 tracks on the edge of a mylar?
flexible cable. On the good side the damage is very accessible but the bad
bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally one would
just replace the flex pcb but in practice that would involve dismantling the
camera and lens to get to all the places the pcb branches out to, and in
some places it actually goes into the lens mechanism itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My other
idea is to make my own miniature insulation displacement/piercing connector
using a stack of razor blade bits sandwiched with insulation layers.

The last option would be to use wire links and solder but I think this could
only be done with some sort of mechanical micropositioning rig in view of
the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has any.

Cheers



Ian

This is "not unlike" fixing a PCB trace. How would you do that?

What about globbing some eutectic solder over the traces (even though it
shorts them), then using "something" to break the solder into individual
"strands" while it's still liquid?

I'm wondering whether zebra strip would be conductive enough? It might not
matter over such a short (ar, ar) distance.

I wish you success. And if this happened this morning, please put it aside
and relax. Work on something else, something easy, and try to forget about
this problem for the time being.

On Thu, 29 Jul 2010 07:47:37 -0700, William Sommerwerck wrote:

This is "not unlike" fixing a PCB trace. How would you do that?

What about globbing some eutectic solder over the traces (even though it
shorts them), then using "something" to break the solder into individual
"strands" while it's still liquid?

I'm wondering whether zebra strip would be conductive enough? It might
not matter over such a short (ar, ar) distance.

I wish you success. And if this happened this morning, please put it
aside and relax. Work on something else, something easy, and try to
forget about this problem for the time being.

Flexible pcb connector as in a ribbon connector? I've had some limited
success repairing these with conductive paint designed to repair
automotive window heaters.

Ian P wrote in message
...
In the course of doing some modifications to a very expensive Sony 3 chip
HD
camcorder I have accidentally cut through 3 tracks on the edge of a mylar?
flexible cable. On the good side the damage is very accessible but the bad
bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally one would
just replace the flex pcb but in practice that would involve dismantling
the
camera and lens to get to all the places the pcb branches out to, and in
some places it actually goes into the lens mechanism itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My other
idea is to make my own miniature insulation displacement/piercing
connector
using a stack of razor blade bits sandwiched with insulation layers.

The last option would be to use wire links and solder but I think this
could
only be done with some sort of mechanical micropositioning rig in view of
the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

Cheers



Ian




Assuming you're not in a stripline-type situation with ground plane/rf
considerations, try plaiting some magnet wire and soldering to the 3 pcb
solder points at either end of the plaited section of "ribbon", you may
have to make a hole through the pcb though.

"Ian P" wrote in message
...
In the course of doing some modifications to a very expensive Sony 3 chip
HD camcorder I have accidentally cut through 3 tracks on the edge of a
mylar? flexible cable. On the good side the damage is very accessible but
the bad bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally
one would just replace the flex pcb but in practice that would involve
dismantling the camera and lens to get to all the places the pcb branches
out to, and in some places it actually goes into the lens mechanism
itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My other
idea is to make my own miniature insulation displacement/piercing
connector using a stack of razor blade bits sandwiched with insulation
layers.

The last option would be to use wire links and solder but I think this
could only be done with some sort of mechanical micropositioning rig in
view of the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

Cheers



Ian



Based on my experience of trying to repair accidental damage to flexiprints
(yes, it happens to us all no matter how long we've been in the game and how
experienced we are !) I think that you are going to struggle to get a fix on
one of that tiny pitch. I have had plenty of success with abrading and
soldering ones of a slightly greater pitch, doing it with a tiny
needle-point soldering tip and under a microscope, and using a single strand
from superflex instrument cable, such as is used for better quality meter
leads, for instance.

I don't know whether this is a commercial job, or one for a friend, or maybe
even for yourself, but before you commit to any strategy that's going to
waste a lot of time, and end up with no fix at the end of it anyway, the job
would probably stand being left for a day or two, before revisiting it with
a clear head, to look at how hard replacing the flexiprint would *really*
be. I've often found that things that look as though they are going to be a
copper-bottomed-gold-plated bitch to do, are actually not so bad, when
looked at again after you've calmed down, and forced a degree of 'san fairy
ann' into your head over it. If you have a copy of the service manual or can
obtain one, a look at the parts list will tell you if replacement is even an
option (if you're really unlucky it might be an integral part of the lens
assembly) and if it is available, a look at the exploded view diagram, would
be helpful to determine how many 'hidden' branches the flexiprint has, and
where they go.

I really feel for you on this one. I've been there many times over the years
....

Good luck with it, and please post back, and let us know how you get on with
it :-\

Arfa

"William Sommerwerck" wrote in message
...
This is "not unlike" fixing a PCB trace. How would you do that?

What about globbing some eutectic solder over the traces (even though it
shorts them), then using "something" to break the solder into individual
"strands" while it's still liquid?

I'm wondering whether zebra strip would be conductive enough? It might not
matter over such a short (ar, ar) distance.

I wish you success. And if this happened this morning, please put it aside
and relax. Work on something else, something easy, and try to forget about
this problem for the time being.



William

I too wondered about how conductive zebra strip is but considered it for
this because the tracks are so narrow they are probably only carrying logic
level signals whereas some of the other tracks in this particular flex are
over 1.5mm wide.

It 'happened' several days ago so have got over the initial shock and
annoyance with myself. I am not rushing in until feel right.

Ian

"Meat Plow" wrote in message
news
On Thu, 29 Jul 2010 07:47:37 -0700, William Sommerwerck wrote:

This is "not unlike" fixing a PCB trace. How would you do that?

What about globbing some eutectic solder over the traces (even though it
shorts them), then using "something" to break the solder into individual
"strands" while it's still liquid?

I'm wondering whether zebra strip would be conductive enough? It might
not matter over such a short (ar, ar) distance.

I wish you success. And if this happened this morning, please put it
aside and relax. Work on something else, something easy, and try to
forget about this problem for the time being.

Flexible pcb connector as in a ribbon connector? I've had some limited
success repairing these with conductive paint designed to repair
automotive window heaters.

Its a paper thin flexible pcb, golden brown in colour which I think is made
from Mylar. Because of the narrowness of the tracks and their spacing I
doubt it could be done with paint.

Ian

"N_Cook" wrote in message
...
Ian P wrote in message
...
In the course of doing some modifications to a very expensive Sony 3 chip
HD
camcorder I have accidentally cut through 3 tracks on the edge of a
mylar?
flexible cable. On the good side the damage is very accessible but the
bad
bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally one would
just replace the flex pcb but in practice that would involve dismantling
the
camera and lens to get to all the places the pcb branches out to, and in
some places it actually goes into the lens mechanism itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My
other
idea is to make my own miniature insulation displacement/piercing
connector
using a stack of razor blade bits sandwiched with insulation layers.

The last option would be to use wire links and solder but I think this
could
only be done with some sort of mechanical micropositioning rig in view of
the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

Cheers



Ian




Assuming you're not in a stripline-type situation with ground plane/rf
considerations, try plaiting some magnet wire and soldering to the 3 pcb
solder points at either end of the plaited section of "ribbon", you may
have to make a hole through the pcb though.


Its just low level analogue signals but the break is close to the end of the
ribbon where the tracks are gold plated to fit in the board connector. The
copper conductors are encapsulated in the Mylar and drilling through the
track which is only 0.004" wide would not be easy!

Ian

It happened several days ago so have got over the initial shock
and annoyance with myself. I am not rushing in until feel right.

Good. That means you'll probably come up with the "least bad" solution.

"Arfa Daily" wrote in message
news:bHh4o.61130$0e3.22364@hurricane...


"Ian P" wrote in message
...
In the course of doing some modifications to a very expensive Sony 3 chip
HD camcorder I have accidentally cut through 3 tracks on the edge of a
mylar? flexible cable. On the good side the damage is very accessible but
the bad bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally
one would just replace the flex pcb but in practice that would involve
dismantling the camera and lens to get to all the places the pcb branches
out to, and in some places it actually goes into the lens mechanism
itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My
other idea is to make my own miniature insulation displacement/piercing
connector using a stack of razor blade bits sandwiched with insulation
layers.

The last option would be to use wire links and solder but I think this
could only be done with some sort of mechanical micropositioning rig in
view of the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

Cheers



Ian



Based on my experience of trying to repair accidental damage to
flexiprints (yes, it happens to us all no matter how long we've been in
the game and how experienced we are !) I think that you are going to
struggle to get a fix on one of that tiny pitch. I have had plenty of
success with abrading and soldering ones of a slightly greater pitch,
doing it with a tiny needle-point soldering tip and under a microscope,
and using a single strand from superflex instrument cable, such as is used
for better quality meter leads, for instance.

I don't know whether this is a commercial job, or one for a friend, or
maybe even for yourself, but before you commit to any strategy that's
going to waste a lot of time, and end up with no fix at the end of it
anyway, the job would probably stand being left for a day or two, before
revisiting it with a clear head, to look at how hard replacing the
flexiprint would *really* be. I've often found that things that look as
though they are going to be a copper-bottomed-gold-plated bitch to do, are
actually not so bad, when looked at again after you've calmed down, and
forced a degree of 'san fairy ann' into your head over it. If you have a
copy of the service manual or can obtain one, a look at the parts list
will tell you if replacement is even an option (if you're really unlucky
it might be an integral part of the lens assembly) and if it is available,
a look at the exploded view diagram, would be helpful to determine how
many 'hidden' branches the flexiprint has, and where they go.

I really feel for you on this one. I've been there many times over the
years ...

Good luck with it, and please post back, and let us know how you get on
with it :-\

Arfa

Arfa

Thanks for your advice. As you postulated this pcb is integral with the lens
and although I have the full service manual for the camera it give no
information at all on the lens which is a bought in item (not removable
though). The job is not really commercial, for a friend or myself but it a
sort of combination of all three. I caused the damage though and I need to
repair it because there is not really any alternative.

I have in the past repaired and modified boards and components and used thin
wire just as you described, this cable though has track and spacing widths
that are really challenging, and I don't have any microscope.

I have lots of old bits of similar flexible boards and cables so I am going
to experiment with them.

Ian

Thanks for your advice. As you postulated this pcb is integral with the
lens and although I have the full service manual for the camera it give no
information at all on the lens which is a bought in item (not removable
though). The job is not really commercial, for a friend or myself but it a
sort of combination of all three. I caused the damage though and I need
to repair it because there is not really any alternative.

I have in the past repaired and modified boards and components and used
thin wire just as you described, this cable though has track and spacing
widths that are really challenging, and I don't have any microscope.

I have lots of old bits of similar flexible boards and cables so I am
going
to experiment with them.

I'm starting to get the feeling that maybe you should "bite the bullet" and
have Sony do the repair. It's going to cost a lot of money, but it might be
worth it, simply in the grief saved.

On Thu, 29 Jul 2010 15:17:56 +0100, "Ian P" wrote:

In the course of doing some modifications to a very expensive Sony 3 chip HD
camcorder I have accidentally cut through 3 tracks on the edge of a mylar?
flexible cable. On the good side the damage is very accessible but the bad
bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally one would
just replace the flex pcb but in practice that would involve dismantling the
camera and lens to get to all the places the pcb branches out to, and in
some places it actually goes into the lens mechanism itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My other
idea is to make my own miniature insulation displacement/piercing connector
using a stack of razor blade bits sandwiched with insulation layers.

The last option would be to use wire links and solder but I think this could
only be done with some sort of mechanical micropositioning rig in view of
the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has any.

I feel for you, it's a serious oops moment to recover from.

Contact Sony for an idea of cost of fix, so you can place importance
of fixing yourself in your mind? If you can afford the fix at least
there's a way out.

You've got stuff to practice with, but I can't see how you're going to
reliably connect to that fine pitch. Are there accessible places where
the cut tracks get wider? Do the cut tracks terminate to accessible
places where you can create another, separate cable to bridge the
breaks?

IOW, sidestep trying to repair the damage by creating an alternate
circuit.

Seems to me it's a cable replacement, but that could be sub-assembly
replacement if the flex also gets glued in place to some smaller parts.

Take it easy, it is not a rush job.

Grant.

"William Sommerwerck" wrote in message
...
Thanks for your advice. As you postulated this pcb is integral with the
lens and although I have the full service manual for the camera it give
no
information at all on the lens which is a bought in item (not removable
though). The job is not really commercial, for a friend or myself but it
a
sort of combination of all three. I caused the damage though and I need
to repair it because there is not really any alternative.

I have in the past repaired and modified boards and components and used
thin wire just as you described, this cable though has track and spacing
widths that are really challenging, and I don't have any microscope.

I have lots of old bits of similar flexible boards and cables so I am
going
to experiment with them.

I'm starting to get the feeling that maybe you should "bite the bullet"
and
have Sony do the repair. It's going to cost a lot of money, but it might
be
worth it, simply in the grief saved.



I am not sure that Sony would want to repair the camera now because I was in
the process of carrying out electromechanical modifications so its a bit non
standard.

Ian

"Grant" wrote in message
...
On Thu, 29 Jul 2010 15:17:56 +0100, "Ian P" wrote:

In the course of doing some modifications to a very expensive Sony 3 chip
HD
camcorder I have accidentally cut through 3 tracks on the edge of a mylar?
flexible cable. On the good side the damage is very accessible but the bad
bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally one would
just replace the flex pcb but in practice that would involve dismantling
the
camera and lens to get to all the places the pcb branches out to, and in
some places it actually goes into the lens mechanism itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My other
idea is to make my own miniature insulation displacement/piercing
connector
using a stack of razor blade bits sandwiched with insulation layers.

The last option would be to use wire links and solder but I think this
could
only be done with some sort of mechanical micropositioning rig in view of
the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

I feel for you, it's a serious oops moment to recover from.

Contact Sony for an idea of cost of fix, so you can place importance
of fixing yourself in your mind? If you can afford the fix at least
there's a way out.

You've got stuff to practice with, but I can't see how you're going to
reliably connect to that fine pitch. Are there accessible places where
the cut tracks get wider? Do the cut tracks terminate to accessible
places where you can create another, separate cable to bridge the
breaks?

IOW, sidestep trying to repair the damage by creating an alternate
circuit.

Seems to me it's a cable replacement, but that could be sub-assembly
replacement if the flex also gets glued in place to some smaller parts.

Take it easy, it is not a rush job.

Grant.

The subassembly in question is the lens. Parts of the cable are wrapped
round and glued to the lens body, and the only way to access it is to
completely dismantle the bulk of the camera, more or less reversing the
original manufacturers assembly procedure.

Ian

Ian P wrote:

"Grant" ? wrote in message
...
? On Thu, 29 Jul 2010 15:17:56 +0100, "Ian P" ? wrote:
?
??In the course of doing some modifications to a very expensive Sony 3 chip
??HD
??camcorder I have accidentally cut through 3 tracks on the edge of a mylar?
??flexible cable. On the good side the damage is very accessible but the bad
??bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally one would
??just replace the flex pcb but in practice that would involve dismantling
??the
??camera and lens to get to all the places the pcb branches out to, and in
??some places it actually goes into the lens mechanism itself.
??
??I am considering abrading off the top mylar coating to expose the copper
??then bridging the breaks with some very narrow pitch zebra strip. My other
??idea is to make my own miniature insulation displacement/piercing
??connector
??using a stack of razor blade bits sandwiched with insulation layers.
??
??The last option would be to use wire links and solder but I think this
??could
??only be done with some sort of mechanical micropositioning rig in view of
??the small sizes involved.
??
??I would be interested to hear any thoughts or experiences if anyone has
??any.
?
? I feel for you, it's a serious oops moment to recover from.
?
? Contact Sony for an idea of cost of fix, so you can place importance
? of fixing yourself in your mind? If you can afford the fix at least
? there's a way out.
?
? You've got stuff to practice with, but I can't see how you're going to
? reliably connect to that fine pitch. Are there accessible places where
? the cut tracks get wider? Do the cut tracks terminate to accessible
? places where you can create another, separate cable to bridge the
? breaks?
?
? IOW, sidestep trying to repair the damage by creating an alternate
? circuit.
?
? Seems to me it's a cable replacement, but that could be sub-assembly
? replacement if the flex also gets glued in place to some smaller parts.
?
? Take it easy, it is not a rush job.
?
? Grant.

The subassembly in question is the lens. Parts of the cable are wrapped
round and glued to the lens body, and the only way to access it is to
completely dismantle the bulk of the camera, more or less reversing the
original manufacturers assembly procedure.


Look for a dead unit on ebay for parts.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

"Ian P" wrote in message
...

"Arfa Daily" wrote in message
news:bHh4o.61130$0e3.22364@hurricane...


"Ian P" wrote in message
...
In the course of doing some modifications to a very expensive Sony 3
chip HD camcorder I have accidentally cut through 3 tracks on the edge
of a mylar? flexible cable. On the good side the damage is very
accessible but the bad bit is the tracks are only 0.1mm wide on a 0.2mm
pitch! Ideally one would just replace the flex pcb but in practice that
would involve dismantling the camera and lens to get to all the places
the pcb branches out to, and in some places it actually goes into the
lens mechanism itself.

I am considering abrading off the top mylar coating to expose the copper
then bridging the breaks with some very narrow pitch zebra strip. My
other idea is to make my own miniature insulation displacement/piercing
connector using a stack of razor blade bits sandwiched with insulation
layers.

The last option would be to use wire links and solder but I think this
could only be done with some sort of mechanical micropositioning rig in
view of the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

Cheers



Ian



Based on my experience of trying to repair accidental damage to
flexiprints (yes, it happens to us all no matter how long we've been in
the game and how experienced we are !) I think that you are going to
struggle to get a fix on one of that tiny pitch. I have had plenty of
success with abrading and soldering ones of a slightly greater pitch,
doing it with a tiny needle-point soldering tip and under a microscope,
and using a single strand from superflex instrument cable, such as is
used for better quality meter leads, for instance.

I don't know whether this is a commercial job, or one for a friend, or
maybe even for yourself, but before you commit to any strategy that's
going to waste a lot of time, and end up with no fix at the end of it
anyway, the job would probably stand being left for a day or two, before
revisiting it with a clear head, to look at how hard replacing the
flexiprint would *really* be. I've often found that things that look as
though they are going to be a copper-bottomed-gold-plated bitch to do,
are actually not so bad, when looked at again after you've calmed down,
and forced a degree of 'san fairy ann' into your head over it. If you
have a copy of the service manual or can obtain one, a look at the parts
list will tell you if replacement is even an option (if you're really
unlucky it might be an integral part of the lens assembly) and if it is
available, a look at the exploded view diagram, would be helpful to
determine how many 'hidden' branches the flexiprint has, and where they
go.

I really feel for you on this one. I've been there many times over the
years ...

Good luck with it, and please post back, and let us know how you get on
with it :-\

Arfa

Arfa

Thanks for your advice. As you postulated this pcb is integral with the
lens and although I have the full service manual for the camera it give no
information at all on the lens which is a bought in item (not removable
though). The job is not really commercial, for a friend or myself but it a
sort of combination of all three. I caused the damage though and I need to
repair it because there is not really any alternative.

I have in the past repaired and modified boards and components and used
thin wire just as you described, this cable though has track and spacing
widths that are really challenging, and I don't have any microscope.

I have lots of old bits of similar flexible boards and cables so I am
going to experiment with them.

Ian

Another possibility, if you get to the point of 'kill or cure', and
depending on how much space you've got to play with. I have had considerable
success on remaking the ends of flexiprints, that have failed from bending
at the stiffening film at the connection point. You can carefully knife off
the last few mm of cable, then re-expose the print 'fingers' by abrading the
plastic. I actually use a blunt curved scalpel blade. Once the fingers have
been thus exposed, the cable can be reinserted in the connector, and then
the original stiffener pushed back in behind to give a good tension on the
connector again. Suppose now that you could cut right across where the
damage is, and re-expose connector fingers at each cut end. If you could
then obtain connectors, and solder them back to back, you could then use
this as a joint to remake your cable. I realise that with such a fine pitch,
the soldering would not be easy, but at least you would be doing it on the
bench, in the open, and with good light. A strong magnifier would be enough
to be able to see what you are doing, and some liquid flux, and desoldering
braid, should make the job do-able.

Along similar lines, another possibility might be to again cut right across
the cable, and expose the conductors on the upper surface of one end, and
the lower of the other. Then treat it as a surface mount soldering job. If
you use liquid flux, solder paste, and hot air, and do a good job of lining
up the tracks and preventing movement before you start, there's a good
chance of success at making a satisfactory join. Capillary action will pull
the solder onto the tracks, and providing you've been sparing with it, there
shouldn't be any shorts between tracks.

Arfa

Ian P wrote in message
...

"N_Cook" wrote in message
...
Ian P wrote in message
...
In the course of doing some modifications to a very expensive Sony 3
chip
HD
camcorder I have accidentally cut through 3 tracks on the edge of a
mylar?
flexible cable. On the good side the damage is very accessible but the
bad
bit is the tracks are only 0.1mm wide on a 0.2mm pitch! Ideally one
would
just replace the flex pcb but in practice that would involve
dismantling
the
camera and lens to get to all the places the pcb branches out to, and
in
some places it actually goes into the lens mechanism itself.

I am considering abrading off the top mylar coating to expose the
copper
then bridging the breaks with some very narrow pitch zebra strip. My
other
idea is to make my own miniature insulation displacement/piercing
connector
using a stack of razor blade bits sandwiched with insulation layers.

The last option would be to use wire links and solder but I think this
could
only be done with some sort of mechanical micropositioning rig in view
of
the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

Cheers



Ian




Assuming you're not in a stripline-type situation with ground plane/rf
considerations, try plaiting some magnet wire and soldering to the 3 pcb
solder points at either end of the plaited section of "ribbon", you may
have to make a hole through the pcb though.


Its just low level analogue signals but the break is close to the end of
the
ribbon where the tracks are gold plated to fit in the board connector. The
copper conductors are encapsulated in the Mylar and drilling through the
track which is only 0.004" wide would not be easy!

Ian




No, making hole/s through the pcb, to take the plait, so you can make proper
solder joins to pre-existing solder joints on the ribbon sockets

Ian P wrote in message
...

"Meat Plow" wrote in message
news
On Thu, 29 Jul 2010 07:47:37 -0700, William Sommerwerck wrote:

This is "not unlike" fixing a PCB trace. How would you do that?

What about globbing some eutectic solder over the traces (even though
it
shorts them), then using "something" to break the solder into
individual
"strands" while it's still liquid?

I'm wondering whether zebra strip would be conductive enough? It might
not matter over such a short (ar, ar) distance.

I wish you success. And if this happened this morning, please put it
aside and relax. Work on something else, something easy, and try to
forget about this problem for the time being.

Flexible pcb connector as in a ribbon connector? I've had some limited
success repairing these with conductive paint designed to repair
automotive window heaters.

Its a paper thin flexible pcb, golden brown in colour which I think is
made
from Mylar. Because of the narrowness of the tracks and their spacing I
doubt it could be done with paint.

Ian




If heat resistant then probably kapton tape. If signal levels and you have a
fairy godmother then anisotropic tape is another possibility , if you can
bare back to the underlying condusctors .

"Arfa Daily" wrote in message
news:gcp4o.319800$Yb4.133179@hurricane...


"Ian P" wrote in message
...

"Arfa Daily" wrote in message
news:bHh4o.61130$0e3.22364@hurricane...


"Ian P" wrote in message
...
In the course of doing some modifications to a very expensive Sony 3
chip HD camcorder I have accidentally cut through 3 tracks on the edge
of a mylar? flexible cable. On the good side the damage is very
accessible but the bad bit is the tracks are only 0.1mm wide on a 0.2mm
pitch! Ideally one would just replace the flex pcb but in practice that
would involve dismantling the camera and lens to get to all the places
the pcb branches out to, and in some places it actually goes into the
lens mechanism itself.

I am considering abrading off the top mylar coating to expose the
copper then bridging the breaks with some very narrow pitch zebra
strip. My other idea is to make my own miniature insulation
displacement/piercing connector using a stack of razor blade bits
sandwiched with insulation layers.

The last option would be to use wire links and solder but I think this
could only be done with some sort of mechanical micropositioning rig in
view of the small sizes involved.

I would be interested to hear any thoughts or experiences if anyone has
any.

Cheers



Ian



Based on my experience of trying to repair accidental damage to
flexiprints (yes, it happens to us all no matter how long we've been in
the game and how experienced we are !) I think that you are going to
struggle to get a fix on one of that tiny pitch. I have had plenty of
success with abrading and soldering ones of a slightly greater pitch,
doing it with a tiny needle-point soldering tip and under a microscope,
and using a single strand from superflex instrument cable, such as is
used for better quality meter leads, for instance.

I don't know whether this is a commercial job, or one for a friend, or
maybe even for yourself, but before you commit to any strategy that's
going to waste a lot of time, and end up with no fix at the end of it
anyway, the job would probably stand being left for a day or two, before
revisiting it with a clear head, to look at how hard replacing the
flexiprint would *really* be. I've often found that things that look as
though they are going to be a copper-bottomed-gold-plated bitch to do,
are actually not so bad, when looked at again after you've calmed down,
and forced a degree of 'san fairy ann' into your head over it. If you
have a copy of the service manual or can obtain one, a look at the parts
list will tell you if replacement is even an option (if you're really
unlucky it might be an integral part of the lens assembly) and if it is
available, a look at the exploded view diagram, would be helpful to
determine how many 'hidden' branches the flexiprint has, and where they
go.

I really feel for you on this one. I've been there many times over the
years ...

Good luck with it, and please post back, and let us know how you get on
with it :-\

Arfa

Arfa

Thanks for your advice. As you postulated this pcb is integral with the
lens and although I have the full service manual for the camera it give
no information at all on the lens which is a bought in item (not
removable though). The job is not really commercial, for a friend or
myself but it a sort of combination of all three. I caused the damage
though and I need to repair it because there is not really any
alternative.

I have in the past repaired and modified boards and components and used
thin wire just as you described, this cable though has track and spacing
widths that are really challenging, and I don't have any microscope.

I have lots of old bits of similar flexible boards and cables so I am
going to experiment with them.

Ian

Another possibility, if you get to the point of 'kill or cure', and
depending on how much space you've got to play with. I have had
considerable success on remaking the ends of flexiprints, that have failed
from bending at the stiffening film at the connection point. You can
carefully knife off the last few mm of cable, then re-expose the print
'fingers' by abrading the plastic. I actually use a blunt curved scalpel
blade. Once the fingers have been thus exposed, the cable can be
reinserted in the connector, and then the original stiffener pushed back
in behind to give a good tension on the connector again. Suppose now that
you could cut right across where the damage is, and re-expose connector
fingers at each cut end. If you could then obtain connectors, and solder
them back to back, you could then use this as a joint to remake your
cable. I realise that with such a fine pitch, the soldering would not be
easy, but at least you would be doing it on the bench, in the open, and
with good light. A strong magnifier would be enough to be able to see what
you are doing, and some liquid flux, and desoldering braid, should make
the job do-able.

Along similar lines, another possibility might be to again cut right
across the cable, and expose the conductors on the upper surface of one
end, and the lower of the other. Then treat it as a surface mount
soldering job. If you use liquid flux, solder paste, and hot air, and do a
good job of lining up the tracks and preventing movement before you start,
there's a good chance of success at making a satisfactory join. Capillary
action will pull the solder onto the tracks, and providing you've been
sparing with it, there shouldn't be any shorts between tracks.

Arfa


Arfa

You have made some very good suggestions there and I can tell you've had
some experience in repairing things others would not even consider! I can
see no reason why the lapped joint idea wouldn't work, however the backside
of the flex is probably the substrate that the copper was plated onto and
scraping that off might be very tricky.

I'm leaning towards fine wire soldered jumpers across the breaks.

Ian

In article ,
"Ian P" wrote:

I'm leaning towards fine wire soldered jumpers across the breaks.

I wouldn't hesitate to do this, but I'd not attempt it whatsoever
without a microscope. Can you borrow one?

"Smitty Two" wrote in message
news
In article ,
"Ian P" wrote:

I'm leaning towards fine wire soldered jumpers across the breaks.

I wouldn't hesitate to do this, but I'd not attempt it whatsoever
without a microscope. Can you borrow one?

Unfortunately I don't have anything other than strong magnifying glasses and
I cannot think of anyone or anywhere I could borrow one from.

In the past I have tried soldering etc whilst looking through a magnifying
glass but have struggled because of only really looking through one eye so
really stereo magnification is what I need.

Ian

"Ian P" wrote in
:


"Smitty Two" wrote in message
news
In article ,
"Ian P" wrote:

I'm leaning towards fine wire soldered jumpers across the breaks.

I wouldn't hesitate to do this, but I'd not attempt it whatsoever
without a microscope. Can you borrow one?

Unfortunately I don't have anything other than strong magnifying glasses
and I cannot think of anyone or anywhere I could borrow one from.

In the past I have tried soldering etc whilst looking through a
magnifying glass but have struggled because of only really looking
through one eye so really stereo magnification is what I need.

Do you have a video camera that can do closeups?
Can you work while watching what you are doing via a monitor?

If you have a piece of similar cable that you can glue along side the cut
one, you might be able to use straight pins to pierce both conductors
simultaneously and then turn the pins into 'rivets' permanently connecting
the broken conductors through the 'bridging' conductor.
Stagger the 'rivets' so they don't short to each other.

You may be able to get some very thin diameter straight pins such as used
for mounting butterflies or from a hobby store, used as nails, etc on small
models. Perhaps even with a copper coating, so that you could touch them
with a bit of solder to 'make things permanent'.

Try it first on some pieces of similar flex from the trash/junk box.

Stagger the pins to give more room to work.

Good luck!

On Jul 29, 7:17*am, "Ian P" wrote:
In the course of doing some modifications to a very expensive Sony 3 chip HD
camcorder I have accidentally cut through 3 tracks on the edge of a mylar?
flexible cable.

If you're very lucky, there are redundant traces and you
can jumper to them from the nonworking conductors at the
connectors (on the non-flexing boards). Otherwise, contact
Sony for a new part (or subassembly).

After mulling over all the good guidance and advice I recieved in response
to my original posting I decided which method to use and this evening have
successfully repaired the cut tracks.

I went for the soldered wire jumpers over the breaks, straightforward under
normal circumstances but in this case on a small scale. I bridged four
adjacent tracks using wire 0,05mm (2 thou) diameter taken from super
flexible test lead wire. The tracks were were between 0.1 and 0.15mm wide
and the whole repaired area ended up 0.9mm wide and 4mm long.

With the right equipment, microscope etc I can now see that a repair of this
sort could be done fairly easily, I managed with a strong magnifyng glass
that I fixed in place so I had both hands free. After I fixed the first
jumper I improved my technique and was able to work one handed by using a
longer length of jumper held taught exactly in line with the track by bits
of masking tape at either end. Because of its length its really easy to
position the jumper, I also put a little bit of packing under the ribbon so
that it formed a raised surface to keep the wire in contact with the
previously tinned tracks.

I still have to test the repair but mechanically all the joints are sound
and separated from each other so I'm happy.

Many thanks to all that responded.

Ian

"Ian P" wrote in message
...
After mulling over all the good guidance and advice I recieved in response
to my original posting I decided which method to use and this evening have
successfully repaired the cut tracks.

I went for the soldered wire jumpers over the breaks, straightforward
under normal circumstances but in this case on a small scale. I bridged
four adjacent tracks using wire 0,05mm (2 thou) diameter taken from super
flexible test lead wire. The tracks were were between 0.1 and 0.15mm wide
and the whole repaired area ended up 0.9mm wide and 4mm long.

With the right equipment, microscope etc I can now see that a repair of
this sort could be done fairly easily, I managed with a strong magnifyng
glass that I fixed in place so I had both hands free. After I fixed the
first jumper I improved my technique and was able to work one handed by
using a longer length of jumper held taught exactly in line with the track
by bits of masking tape at either end. Because of its length its really
easy to position the jumper, I also put a little bit of packing under the
ribbon so that it formed a raised surface to keep the wire in contact with
the previously tinned tracks.

I still have to test the repair but mechanically all the joints are sound
and separated from each other so I'm happy.

Many thanks to all that responded.

Ian


Glad you got a fix ! If the flexiprint doesn't have to bend at the point
where you've repaired it - and I assume that it doesn't as you say that you
have put some strengthening behind it - you might want to coat over the
repair with some clear nail laquer, just to add a bit of 'stay still' to the
wires, and offer a bit of physical protection.

Don't know if you might have a need in the future to do any very fine work
like this again, but if you do, a stereo microscope with built in work lamp
is indispensible. You can pick them up quite cheaply on eBay. Mine came from
Farnell when they had them on offer a few years back. It takes a bit of
getting used to soldering under one, as even the finest tipped iron looks
like a wrought iron poker that the local smithy has just turned out, and the
solder looks like a steel ship hawser, but then even very fine tracks look
like roads, so it's all relative ...

Arfa

On Sat, 31 Jul 2010 23:55:21 +0100, "Ian P" wrote:

After mulling over all the good guidance and advice I recieved in response
to my original posting I decided which method to use and this evening have
successfully repaired the cut tracks.

I went for the soldered wire jumpers over the breaks, straightforward under
normal circumstances but in this case on a small scale. I bridged four
adjacent tracks using wire 0,05mm (2 thou) diameter taken from super
flexible test lead wire. The tracks were were between 0.1 and 0.15mm wide
and the whole repaired area ended up 0.9mm wide and 4mm long.

With the right equipment, microscope etc I can now see that a repair of this
sort could be done fairly easily, I managed with a strong magnifyng glass
that I fixed in place so I had both hands free. After I fixed the first
jumper I improved my technique and was able to work one handed by using a
longer length of jumper held taught exactly in line with the track by bits
of masking tape at either end. Because of its length its really easy to
position the jumper, I also put a little bit of packing under the ribbon so
that it formed a raised surface to keep the wire in contact with the
previously tinned tracks.

I still have to test the repair but mechanically all the joints are sound
and separated from each other so I'm happy.

Many thanks to all that responded.

Great news! Even if it not work first time, sounds like you find a good
technique to repeat.

Grant.

Congratulations! Or should I say "Congratos!"?

On Sat, 31 Jul 2010 23:55:21 +0100, Ian P wrote:

After mulling over all the good guidance and advice I recieved in
response to my original posting I decided which method to use and this
evening have successfully repaired the cut tracks.

I went for the soldered wire jumpers over the breaks, straightforward
under normal circumstances but in this case on a small scale. I bridged
four adjacent tracks using wire 0,05mm (2 thou) diameter taken from
super flexible test lead wire. The tracks were were between 0.1 and
0.15mm wide and the whole repaired area ended up 0.9mm wide and 4mm
long.

With the right equipment, microscope etc I can now see that a repair of
this sort could be done fairly easily, I managed with a strong magnifyng
glass that I fixed in place so I had both hands free. After I fixed the
first jumper I improved my technique and was able to work one handed by
using a longer length of jumper held taught exactly in line with the
track by bits of masking tape at either end. Because of its length its
really easy to position the jumper, I also put a little bit of packing
under the ribbon so that it formed a raised surface to keep the wire in
contact with the previously tinned tracks.

I still have to test the repair but mechanically all the joints are
sound and separated from each other so I'm happy.

Many thanks to all that responded.

Ian

Get yourself a 25x stereo magnifying visor. It's a good investment.

On Sun, 1 Aug 2010 22:15:44 +0000 (UTC), Meat Plow
wrote:

On Sat, 31 Jul 2010 23:55:21 +0100, Ian P wrote:

After mulling over all the good guidance and advice I recieved in
response to my original posting I decided which method to use and this
evening have successfully repaired the cut tracks.

I went for the soldered wire jumpers over the breaks, straightforward
under normal circumstances but in this case on a small scale. I bridged
four adjacent tracks using wire 0,05mm (2 thou) diameter taken from
super flexible test lead wire. The tracks were were between 0.1 and
0.15mm wide and the whole repaired area ended up 0.9mm wide and 4mm
long.

With the right equipment, microscope etc I can now see that a repair of
this sort could be done fairly easily, I managed with a strong magnifyng
glass that I fixed in place so I had both hands free. After I fixed the
first jumper I improved my technique and was able to work one handed by
using a longer length of jumper held taught exactly in line with the
track by bits of masking tape at either end. Because of its length its
really easy to position the jumper, I also put a little bit of packing
under the ribbon so that it formed a raised surface to keep the wire in
contact with the previously tinned tracks.

I still have to test the repair but mechanically all the joints are
sound and separated from each other so I'm happy.

Many thanks to all that responded.

Ian

Get yourself a 25x stereo magnifying visor. It's a good investment.

2.5x (5 diopter)?

--
Rich Webb Norfolk, VA