Author Topic: What household glues, if any, are good for minor PC board repair (loose traces)?  (Read 886 times)

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Offline cvanc

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Hi all-

I've got a piece on the bench that has apparently been dropped 'a little' in the past.  It runs fine, no boards are cracked or anything severe like that.  However, there are some TO-202 transistors with small freestanding heat sinks that have clearly flexed and loosened all the pads they are connected to.  So you can grab them and gently wiggle them and the pads and traces on the other side are loose.   All the connections are good but I'd hate to leave it like this.

I wonder if simply hitting it with a hot glue gun would be OK?  I know that would immobilize things but is hot glue electrically benign?  Or how about good old fashioned super glue (Cyanoacrylate glue)?  Or even epoxy?

If those aren't suitable feel free to advise something that is... thank you.
 

Offline DC1MC

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IMHO and experience, from worst to best you have:

 hot glue - worst and most useless, it changes geometry of the board, it's difficult to put it under the traces and, of course, the biggest problem it is that is not heat resistant and the transistors there will get hot and spread the heat trough the traces ( this is why actually the original PCB glue gets weak round hot spots).

 super glue, aka cyano-acrylate, it's excellent because it's very fluid and easily goes under the trace, and when it grabs, it holds  :D. It also has reasonable HF proprieties, but I suppose you don't have to high of a frequency there. The main weakness it's that it doesn't have long term heat resistance and become brittle, but could still be considered if the temperature it's not so high.

 epoxy, two components glue it's the best IMO if you manage to find the one that when it's cured it becomes transparent glassy, not darkish colour, that is, it doesn't have any added powders for extra mechanical resistance. This type of glue has real strength and it will protect the are good, very good heat tolerance and can be applied relatively easy before polymerization and curing.

 AS usually, IMMV.
 

Online james_s

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There's also that stuff that's sold as Amazing Goop, Shoe Goo, Household Goo, etc, I suspect it's all the same stuff. It's viscous and sticks well to a lot of materials.
 

Offline TMM

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From what you describe, I would epoxy blob it around/over the tracks/leads on both sides of the board. The '5 minute' formulations that come in the dual syringe packs will do what you want.

Cyanoacrylate will probably be too brittle and crack. Common hot melt glues usually have a very low melting point and will soften and start to drip/flow at as little as 60-80*C.
 

Offline BradC

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Common hot melt glues usually have a very low melting point and will soften and start to drip/flow at as little as 60-80*C.

So do most common 5 minute epoxies. If you want higher heat resistance you'll want to use a slower curing epoxy and some post cure heat.
 

Offline TMM

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Common hot melt glues usually have a very low melting point and will soften and start to drip/flow at as little as 60-80*C.

So do most common 5 minute epoxies. If you want higher heat resistance you'll want to use a slower curing epoxy and some post cure heat.
The 5 minute epoxies I have used are good to a least 100*C. It may become slightly softer, but still nowhere near as soft as room temperature hot melt glue and won't migrate to another location at that temp like hot melt glue will do. The melting point of epoxy (completely liquid) is somewhere north of 150*C. The slower setting epoxy formations have higher yield strength than the 5minute ones but they are also more flexible and as far as i'm aware the ones that you can get from a local hardware store aren't any better than the 5minute versions at standing up to heat.
 

Offline BradC

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The 5 minute epoxies I have used are good to a least 100*C..

Can I get a name? I've tried araldite and jb-Kwik and both of those soften below 100C. 24hr araldite with a post cure heat does ok. If it's something I can get relatively easily I'm there.
 

Offline SeanB

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Would not use the goo type glues, they tend to chemically react with time and heat and turn into an acid that eats the board, and which also becomes conductive.

Epoxy, preferably the slow curing types, works well. I have done quite a few cracked board repairs though with epoxy and superglue to bond delaminated SRBP, and for fibreglass epoxy is the best. Just remember with all at least degrease the surfaces with IPA, dry thoroughly and preferably roughen the  smooth surfaces with either sandpaper or a sharp scalpel blade prior to application.

I have used some ABE Epidermix with good results, though it is quite expensive, smells a bit in the uncured state and takes 24 hours to cure after 3 hours of gel time. Non hot I have used Pratley quickset white, it works well and I have used it to bond heatsinks to hot running integrated circuits before., though there the Pratley quickset steel is also good, just not as good insulating wise.
 

Offline KE5FX

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Bondic.  It's not really an adhesive but it's really good for this kind of thing.
 

Offline branadic

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What I can recommend for trace repair on FR4 boards is UHU Plus endfest 300 (the green one). It's a two component expoy adhesive, that needs some time to dry, but if you can bake the board, you can increase stability of the adhesive join. No problem soldering that trace after glue has dryed. This is one of the best and long lasting glues I know of.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Offline Samogon

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Chemtronics cw2500
This is high temp epoxy overcoat. Specifically designed for circuit boards repair.
 

Offline DC1MC

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Chemtronics cw2500
This is high temp epoxy overcoat. Specifically designed for circuit boards repair.
The best but also the most expensive form the whole gang, at least in EU, but for some device it's worth the price:
http://www.ebay.de/itm/1-st-Sicherungsbeschichtung-7-4g/172980068097
 

Offline Samogon

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Chemtronics cw2500
This is high temp epoxy overcoat. Specifically designed for circuit boards repair.
The best but also the most expensive form the whole gang, at least in EU, but for some device it's worth the price:
http://www.ebay.de/itm/1-st-Sicherungsbeschichtung-7-4g/172980068097
It payed off after two applications one drop each time.
 


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