pcb trace repair

[dnhb]

I'd be grateful to hear about techniques colleagues have tried - successfully or otherwise - for repairing pcb traces in quartz movements.

[watchweasol]

Hi.  You can get a silver oxide conductive paint (not cheap) for re drawing Brocken and cracked tracks. I have used it ti repair coils works ok.  You can get the paint off eBay  ( conductive Paint).

[AndyGSi]

It all depends on the PCB and track size so a photo would help.

[dnhb]

6 minutes ago, AndyGSi said:

It all depends on the PCB and track size so a photo would help.

Thanks for your response. I was interested quite generally but here's the one that lead me to ask for advice (the gap in the trace - caused by corrosion- is where I've placed the sticky-back foil as an initial attempt to understand the scale at which one would have to work if such repair were possible, whatever the technique)

59 minutes ago, watchweasol said:

Hi.  You can get a silver oxide conductive paint (not cheap) for re drawing Brocken and cracked tracks. I have used it ti repair coils works ok.  You can get the paint off eBay  ( conductive Paint).

I had heard of this but reports of its efficacy in online reviews seem to vary widely. Maybe it's an approach in which sucess depends on good preparation (although the watch pcb traces I've tested don't have protective coatings) as well as product quality - is there a brand you'd suggest I try?

[AndyGSi]

From my experience Silver / Conductive paints are only any good for small
breaks in tracks and not suitable when large portions have been corroded.

What's the movement and have you looked for a replacement circuit?

My solution here would be to solder a replacement wire in place of the track.

[dnhb]

3 hours ago, AndyGSi said:

What's the movement and have you looked for a replacement circuit?

My solution here would be to solder a replacement wire in place of the track.

It's from a Casio MQ24 but my intetest is in it (it's not mine) as a test piece for pcb repair.

Thanks for giving your solution but in thinking of such an approach, which I know is used on 'general' electronics pcbs, I'd wondered if the height (qua diameter) of the wire would be an issue in a watch context.

[AndyGSi]

15 minutes ago, dnhb said:

I'd wondered if the height (qua diameter) of the wire would be an issue in a watch context.

I've never had an issue when I've done it but you are having to deal with a hair like wire.

[watchweasol]

Hi a repair like that is best done with a wire soldered at both ends  once continuity has been established and the cut tested run a little super glue along the wire for protection. Too big a break for the paint method I am afraid.

[dnhb]

On 8/17/2024 at 4:57 PM, watchweasol said:

Hi a repair like that is best done with a wire soldered at both ends  once continuity has been established and the cut tested run a little super glue along the wire for protection. Too big a break for the paint method I am afraid.

I went on to buy some conductive tape which was said to be conductive on the adhesive side too. I cut as thin a sliver as could but when I first applied it I couldn't get connectivity. I put the pcb to one side while I researched a smaller soldering iron than the one I had thinking I'd try the technique you mention using perhaps a piece of coil wire. However, when I dug the pcb out recently I found that the break was mended - maybe the adhesive had solidified &/or I'd applied enough pressure with my Multimeter probe to complete the circuit. I half expected that the fix would fail as I re-assembled the watch but to my surprise it began ticking as soon as I inserted the battery keeping good time. The person whose watch it is was delighted when I phoned with the good news as it had some sentimental value. She sent a gratifying message in a thank you card plus a (unsolicited) contribution to my 'Tool Fund'!