Potting Compound Removal from ECU - Page 1
Forum section: electronics / beginners

author: Adam60
author_rank: Regular Contributor
timestamp: April 25, 2017, 01:57:53 am
content: Good Evening.I have an ECU from a marine engine that has a rubber epoxy type coating on the rear of it to seal and probably prevent people from looking inside it. I have seen videos where people have taken such units and boiled them in hot water to remove the coating. Does anyone have any experience doing this or used any other methods that might be better? I am trying to stay away from the stench that comes with heating it up and this sounds like a good method but never tried it before. The outer cover is just a polypropylene cover.I have a pin or two that has corroded off and needs to be replaced. The unit is worth $2600 new so it is worth a shot.

author: Ian.M
author_rank: Super Contributor
timestamp: April 25, 2017, 02:15:02 am
content: First you need to identify the potting compound or at least what degrades it. You'll need to cut enough away as samples you can try soaking in various solvents to see what, if any, can be used to soften it without dissolving the PCB and components. Most epoxies are hard so the fact its rubbery means its more likely to be a silicone or urethane rubber based compound. If it is epoxy, you are in for a world of grief as most PCBs use the epoxy bonded FR4 laminate and chip and other semiconductor packages are usually some form of epoxy so anything that attacks the potting epoxy is likely to damage the PCB and components.

author: joeqsmith
author_rank: Super Contributor
timestamp: April 25, 2017, 02:33:55 am
content: At first I saw Epoxy in the title, then I see rubber type epoxy. I have never seen rubber type epoxy. I have seen a lot of rubber sort of potting and it is easy enough to dig out with a plastic or wooden stick. Something about the size of a pencil with a wedge cut into the end like a chisel works well.I have had to remove some of the hard epoxy stuff to repair one of my ignitions. I used a propane torch and a wooden stick. Slowly heating it and scraping out sections. Fairly quick, maybe a few hours to get it cleaned up enough to do the repairs.

author: Adam60
author_rank: Regular Contributor
timestamp: April 25, 2017, 03:30:48 am
content: Quote from: joeqsmith on April 25, 2017, 02:33:55 amI guess I had that coming. I do know the difference. It is more of a rubbery type compound like silicone based. I have cut around the outside of the compound and it cuts quite easily. I was hoping there was a way to remove it quickly rather than picking away at it. That is why I asked about boiling but that doesn't sound like a good method either now.

author: james_s
author_rank: Super Contributor
timestamp: April 26, 2017, 12:59:38 am
content: It sounds like silicone based potting. I haven't found a good way of removing it other than picking at it, silicone is impervious to practically everything, which is what makes it work well as a sealant and insulator.

author: Teledog
author_rank: Regular Contributor
timestamp: April 26, 2017, 03:19:03 pm
content: If it's silicone, 99% IPAmayhelp loosen it a bit.It won't dissolve silicone, but it tends to weaken the bond.Try to squeeze it in any gaps & then let it sit 30 seconds or so & carefully hack away.IPA is the cat's ass for removing hot glue bonds, BTW!

author: CJay
author_rank: Super Contributor
timestamp: April 26, 2017, 06:42:57 pm
content: Dunno if this is safe for electronics or if it'd be suitable for your potting compound but:http://www.screwfix.com/p/no-nonsense-sealant-remover-100ml/88987