Rewiring flexible circuit board

M-88 · Jul 20, 2018

Good day

I know that probably this will stay unanswered, but still need to try. I happened to have Olympus camera which has several wires disconnected from flexible circuit board. I have obtained service manual and right now I'm reading the diagrams on what goes where. I will need to reattach four wires on board, but unfortunately can't solder them (my hands aren't what they used to be).

Is there any way I can do it without a soldering tool? In fact I know there are "conductive epoxy" and "conductive glue" on the market, but has anyone actually tried it and can give any advise?

P.S. Please don't tell me to take/send the camera to service as I'm not from a country with qualified people in that field and shipping fees to any good repairman abroad will be ridiculous and not worth the effort.

Thank you in advance

Jim Jones · Jul 20, 2018

My experience with conductive glue in circuits handling somewhat more power was not very good. It might work better in low power circuits in cameras, but it might also make doing the job later with solder more difficult.

M-88 · Jul 20, 2018

Jim Jones said:
My experience with conductive glue in circuits handling somewhat more power was not very good. It might work better in low power circuits in cameras, but it might also make doing the job later with solder more difficult.

Unfortunately I don't know how much power goes from Spot metering circuit to main power circuit. Would something powered by two LR44 cells be a high power? As I dug deeper, however, I found that conductive epoxy is better than conductive glue - it's got higher conductivity and less viscosity, so less risk of it flowing to adjacent contacts and shorting them if I get sloppy.

jeffreyg · Jul 20, 2018

What might be helpful for you would be to get a gadget that will hold the parts for you. I have one but do not know what it is called or who makes it. It has a stand and adjustable arms that can accommodate alligator clips and a magnifying glass. All are on balls so they can rotate and be tightened in all directions. I bought it many years ago to hold small objects while I photographed them while needing my hands to be free for the camera. I'll try photographing it with my phone and put it in another reply.

http://www.jeffreyglasser.com/

jeffreyg · Jul 20, 2018

Here's the gadget sorry for the photo quality it's an old phone and I wanted to reply quickly

M-88 · Jul 20, 2018

jeffreyg said:
Here's the gadget sorry for the photo quality it's an old phone and I wanted to reply quickly

View attachment 204496

Thank you! I will look out for it. But the main problem with me is that I'd much rather hold a one-inch glue stick in hand instead of 5 inches long piece of hot metal. The shorter the thing, the better the aim for me.

shutterfinger · Jul 20, 2018

Do an Ebay search for helping hand in tools or soldering aids.
Do not use a soldering iron higher than 15 watts.

M-88 · Jul 20, 2018

Mine is 20W, but its working tip is somewhat big for a circuit that small. Maybe I will use a file to narrow it down. It's copper, should be easy to handle.

So no input on glue/epoxy?

shutterfinger · Jul 20, 2018

M-88 said:
So no input on glue/epoxy?

never heard of it until this thread.

This will work:
https://www.amazon.com/MG-Chemicals-Two-Part-Conductive-Adhesive/dp/B008UH4DB2
Is something similar available in your part of the world?

John Koehrer · Jul 20, 2018

I've just ordered conductive epoxy from the bay because the old stuff I had solidified. Right now I'm just
waiting for the stuff to magically appear in the mailbox.

I've used it in the past with OK results.

CMoore · Jul 20, 2018

How long does the Epoxy take to set.?
Could you get somebody to help you...maybe you can hold down the wire(s) and they can do the soldering.?
good luck

shutterfinger · Jul 20, 2018

CMoore said:
How long does the Epoxy take to set.?

Varies by brand and type formulation, and temperature. 5 to 30 minutes working time with 24 hours cure time at 70°F (room temperature) to a few hours at 150°F which is recommended, at least for the half dozen types I looked at via google search and amazon.

AgX · Jul 20, 2018

M-88 said:
P.S. Please don't tell me to take/send the camera to service as I'm not from a country with qualified people in that field and shipping fees to any good repairman abroad will be ridiculous and not worth the effort.

There is no need to send the camera to camera specialist. Once you made de flexible circuit board accessible, a good local electronics repair workshop accustomed to substituting so called SMD parts can do such soldering work. But in times of dumping a whole broken electronic device, such repair shops are getting more scarce...

CMoore · Jul 20, 2018

shutterfinger said:
Varies by brand and type formulation, and temperature. 5 to 30 minutes working time with 24 hours cure time at 70°F (room temperature) to a few hours at 150°F which is recommended, at least for the half dozen types I looked at via google search and amazon.

My question was kind of rhetorical.
I guess what i SHOULD have asked is.....is this a through hole or surface connection.?
If the wires simply solder to the surface (like an SMD part) even 5 minutes can be a Long Time. Will the wires stay in place, or can they be secured, as the epoxy goes off.?
Anybody familiar with this camera...do the wires go through the board, or do they sit on a trace.?
good luck

AgX · Jul 21, 2018

That "third hand" device shown above should solve all setting time issue.
I use it for soldering, not only as a third hand as such, but to keep flexible things steady during cooling as such can be critical at soldering too.

One may modify/substitute the clamps depending on the job.

Anon Ymous · Jul 21, 2018

M-88 said:
Mine is 20W, but its working tip is somewhat big for a circuit that small. Maybe I will use a file to narrow it down. It's copper, should be easy to handle.

So no input on glue/epoxy?

This may sound counter intuitive, but you don't need a tiny tip to solder any very small pins, so don't file the tip of your iron. You definitely need some flux (a no clean variety) and a tiny bit of solder (leaded, not lead free) on the soldering iron tip. Any shorts can be cleaned with the iron, but the tip has to be free of any solder. If that's not enough, some braid can be used. If you feel that this is not a job for you, then do what AgX hinted at. A laptop repair guy can probably do it in a matter of minutes.

M-88 · Jul 21, 2018

Woah. So much attention. Let me check...

shutterfinger said:
never heard of it until this thread.

This will work:
https://www.amazon.com/MG-Chemicals-Two-Part-Conductive-Adhesive/dp/B008UH4DB2
Is something similar available in your part of the world?

Unfortunately not, but I regularly order stuff from abroad so it'll be here within 14 days or so.

John Koehrer said:
I've just ordered conductive epoxy from the bay because the old stuff I had solidified. Right now I'm just

waiting for the stuff to magically appear in the mailbox.

I've used it in the past with OK results.

Can you recall the brand? Some have better conductivity, others - worse.

CMoore said:
How long does the Epoxy take to set.?

Could you get somebody to help you...maybe you can hold down the wire(s) and they can do the soldering.?
good luck

I could possibly ask my spouse for help, but considering how much she loves my film gear, she'll do everything to ruin it

AgX said:
There is no need to send the camera to camera specialist. Once you made de flexible circuit board accessible, a good local electronics repair workshop accustomed to substituting so called SMD parts can do such soldering work. But in times of dumping a whole broken electronic device, such repair shops are getting more scarce...

Ja, but the pricier the equipment, the higher the "service" price. It'll be around 200 GEL which is roughly the price I paid for a fully functional OM-4

CMoore said:
My question was kind of rhetorical.
I guess what i SHOULD have asked is.....is this a through hole or surface connection.?
If the wires simply solder to the surface (like an SMD part) even 5 minutes can be a Long Time. Will the wires stay in place, or can they be secured, as the epoxy goes off.?
Anybody familiar with this camera...do the wires go through the board, or do they sit on a trace.?
good luck

My circuit board is an older version (ca 1984-85), with no holes. I have checked the service manual already. Wish it had better quality though.

AgX said:
That "third hand" device shown above should solve all setting time issue.
I use it for soldering, not only as a third hand as such, but to keep flexible things steady during cooling as such can be critical at soldering too.

One may modify/substitute the clamps depending on the job.

I think my father had something similar years ago. I should ask him.

M-88 · Jul 21, 2018

Anon Ymous said:
This may sound counter intuitive, but you don't need a tiny tip to solder any very small pins, so don't file the tip of your iron. You definitely need some flux (a no clean variety) and a tiny bit of solder (leaded, not lead free) on the soldering iron tip. Any shorts can be cleaned with the iron, but the tip has to be free of any solder. If that's not enough, some braid can be used. If you feel that this is not a job for you, then do what AgX hinted at. A laptop repair guy can probably do it in a matter of minutes.

I meant "small" because the tip is too wide to touch only one of the contacts. It will inevitably touch the others too. Or maybe I should shop for smaller tool.

Anon Ymous · Jul 21, 2018

M-88 said:
I meant "small" because the tip is too wide to touch only one of the contacts. It will inevitably touch the others too. Or maybe I should shop for smaller tool.

Still not a problem, I've successfuly used a technique called drag soldering with a cheapo "pencil" tip soldering iron with smd chips.
See this example:

M-88 · Jul 21, 2018

Good lord! I'm gonna fry average metering circuit if I do that

shutterfinger · Jul 21, 2018

Look for a pencil tip soldering iron in your area that is less than 25 watts with a conical tip. Any I link to from here will not be compatible with your household power.

M-88 · Jul 21, 2018

shutterfinger said:
Look for a pencil tip soldering iron in your area that is less than 25 watts with a conical tip. Any I link to from here will not be compatible with your household power.

110 Volts are prolematic indeed

My iron has a tip shaped like a screwdriver. It's 20 Watts and I can file it down to pencil shape.

AgX · Jul 21, 2018

Anon Ymous said:
I've successfuly used a technique called drag soldering with a cheapo "pencil" tip soldering iron with smd chips.

This technique, the first sample technique in that video, was new to me.

But in small electronics cases I use no cheapo soldering iron, but one where the temperature can be set and is regulated.

shutterfinger · Jul 21, 2018

M-88 said:
My iron has a tip shaped like a screwdriver. It's 20 Watts and I can file it down to pencil shape.

That's called a chisel tip. Look for a conical (round) tip for it, a different make may fit.

John Koehrer · Jul 21, 2018

[QUOTE="M-88, post: 2098445, member: 87359")

Can you recall the brand? Some have better conductivity, others - worse.

**Not at all, I tossed the original and ordered blindly from the bay.

I could possibly ask my spouse for help, but considering how much she loves my film gear, she'll do everything to ruin it
No matter how small your wife's hands are, getting an extra finger in there is going to end up with conflict with the soldering iron.

.[/QUOTE]

Rewiring flexible circuit board

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