Damaged pads / traces on mobo, repair tips wanted

[eXeler0]

Hi,

Short version:
I could use some tips on how to fix pads and traces that have been damaged on a CD32 motherboard. (In a couple of places, the pad under the caps fell off completely)

Long version:
I have a faulty CD32 (apart from 2 working ones ;-) which I decided to "see what I can do about it". I don't usually do PCB repairs, but I do have some background in DIY electronics from way back in the 90s and I have some basic soldering/desoldering eqipment, multimeters etc...

Now to the problem. The CD32 motherboard had leaky caps and I decided to remove them all.. Some actually fell off because of the corrosion underneath.
And I may have helped damage some additional traces.

The big issue here is how to repair the pads that "fell off" and or fix traces, although traces can always be replaced by wires ;-)

I saw a guy on YouTube who used heat-bed + epoxy glue that can withstand 400deg C then cut out tiny bits of copper foil and glued it back on.
This seemed a bit over my head so I started looking for "Conductive Epoxy Glue". Found one that seemed perfect for the job but Amazon won't ship it to Sweden.
https://www.amazon.co.uk/dp/B003BDMJ...I2WCJQUUBGG3D9
Then I started looking on ebay and found some alternatives.. Typically called silver glue or similar. Ordered a few variants but havent tried them out yet.
Providing I can apply this silver epoxy to the PCB in a controlled manner, is this way of repairing a bad idea or common practice?
Any other methods?

Thanx for your time and potential help

[wmsteele]

The first pad I lifted was on a CD32, basic fix but worked well...



Currently restoring a A600 that was literately swimming in electrolytic fluid, particularity around the modulator. Both of the caps next to audio sockets had broken loose during shipping taking all four pads with them I Plan to fix this with 4 short wires to the nearest via, soldered to the cap and then heat shrink tubing to protect and dab of hot glue.

[eXeler0]

Originally Posted by wmsteele

The first pad I lifted was on a CD32, basic fix but worked well...



Currently restoring a A600 that was literately swimming in electrolytic fluid, particularity around the modulator. Both of the caps next to audio sockets had broken loose during shipping taking all four pads with them I Plan to fix this with 4 short wires to the nearest via, soldered to the cap and then heat shrink tubing to protect and dab of hot glue.

Yea, that was my first thought too, to fix everything with wires, accepting it won't "look pretty"
My second thought was "Conductive glue /cold solder" but I realize once done, any future fixes will be real hard. OTOH, if it works for another 20 years, it's not gonna matter a lot ;-)

[Pat the Cat]

Originally Posted by eXeler0

Hi,
t

I saw a guy on YouTube who used heat-bed + epoxy glue that can withstand 400deg C then cut out tiny bits of copper foil and glued it back on.
This seemed a bit over my head so I started looking for "Conductive Epoxy Glue". Found one that seemed perfect for the job but Amazon won't ship it to Sweden.
https://www.amazon.co.uk/dp/B003BDMJ...I2WCJQUUBGG3D9
Then I started looking on ebay and found some alternatives.. Typically called silver glue or similar. Ordered a few variants but havent tried them out yet.
Providing I can apply this silver epoxy to the PCB in a controlled manner, is this way of repairing a bad idea or common practice?
Any other methods?

Thanx for your time and potential help

The "copper shim" method takes a fair bit of practise to get right, but it works better. As a rule of thumb, I have used it for audio repairs but not for SMD work.

The "conductive epoxy" method takes a similar level of practice, the snag with it can be that it isn't conductive enough for the particular fix. It's OK for power contacts on say a battery powered touch, but you do need quality material for it to work on digital signalling levels.

Silver based epoxy sounds promising though. Never tried it, it could well be ideal, so test out on some old boards and MAKE SURE IT WILL WORK.

One simple way to practise that isn't too expensive - cheap calculator. If you can damage a track / pad and repair it, you can been pretty sure it's going on work inside a CD32.

[Daedalus]

@eXeler0

I think I know the video you're talking about, and that's how I repair lifted pads too. It's not really all that difficult, just needs a steady hand and a little practice. Sometimes if you're not too worried about aesthetics however, just using a jumper wire does the job fine. You have to make sure the capacitor can't move though, as if it's soldered on one side you have a lot of extra stress on the one remaining pad. Some of that high temperature epoxy will do the job there, or a dab of heat glue on the side opposite the good joint (after you've done the soldering obviously )

I would much rather do the repair using thin wire such as Kynar wire than conducting glue, which might become brittle with time and crack. I've used silver paint before for modelling work but always use wire when I can.

[amiman99]

this video should give you info you need: [ Show youtube player ]
Proper way to fix lifted pads.

[Acill]

Originally Posted by amiman99

this video should give you info you need: [ Show youtube player ]
Proper way to fix lifted pads.

Great video! I recommend this one all the time myself.

[eXeler0]

@amiman99 and @Acill
Yes, that is the video I was referring to in the original post, seen it but came to the conclusion it was a step above my comfort level (also, I might be lacking some useful equipment).

@Daedelus do you recommend a certain brand of high temp epoxy you know from experience will work -for gluing pads onto the pcb? Usually some good out there mixed with cheap knock-offs :-)
And I share your scepticism towards conducting glue, but mostly because it's a "novelty" for me :-)

@PatTheCat, good idea to test the silver glue on cheap stuff first. Main reason for my post here is because I'm skeptical about it.

[Zetr0]

Originally Posted by amiman99

this video should give you info you need: [ Show youtube player ]
proper way to fix lifted pads.

Originally Posted by acill

great video! I recommend this one all the time myself.

+1

[Daedalus]

Yep, that's the video I also use the CW2500 epoxy that he mentions. It's expensive but you really only need a tiny amount, and it's good for years. Farnell / Element 14 stock it and is where I got it, though in the UK at least it's currently on backorder: http://uk.farnell.com/chemtronics/cw...oat/dp/1663186

[eXeler0]

Originally Posted by Daedalus

Yep, that's the video I also use the CW2500 epoxy that he mentions. It's expensive but you really only need a tiny amount, and it's good for years. Farnell / Element 14 stock it and is where I got it, though in the UK at least it's currently on backorder: http://uk.farnell.com/chemtronics/cw...oat/dp/1663186

Ah yes Chemtronics, thanx.. Now I see they actually have a reseller in Sweden with "better pricing"
http://www.digikey.se/product-detail...es&pmt=b&pdv=c
I'm a little worried of the "properly cured" part. Is a heat-bed necessary or what is the recommended process?

Speaking of Chemtronic..
This is the sort of thing I'd rather use, but damn the price.. (Might as well get a new CD32 mobo for that kind of money.)
http://www.ebay.com/itm/CHEMTRONICS-...4AAOSwhkRWdC-B

[Daedalus]

A heat bed isn't required, no, but it will make it much faster. The tubes themselves specify 4 hours at 25 degrees C to cure, so a reasonably warm room should be fine. I would generally give any epoxy 24 hours to reach full strength if at all possible however - a head bed might reduce that time down to an hour or two instead.

Yeah, the conducting pen might be useful alright, but that is pretty expensive!

[Pat the Cat]

Originally Posted by eXeler0

@PatTheCat, good idea to test the silver glue on cheap stuff first.

I am in similar position to you - lots of through hole experience, very limited SMD experience.

So it's practice, practice, practice to get skill levels and confidence higher.

[ptyerman]

There is this: http://www.maplin.co.uk/p/electrical...er-paint-n36ba which is a lot cheaper than what you linked to.
I have used this in the past to repair a VGA Geforce card that had a worn connector and wouldn't work when plugged in a VGA slot. After carefully applying a thin sliver of this to the edge connector and letting it dry overnight it worked.
Googling silver conductive pen also gives several links you might like to investigate.

[idrougge]

I would just use wire, and have done so on my severely damaged A4000. If doing so, you may also use standard through-hole capacitors if you prefer to connect them that way.