2G ECU protective coating pulled up after cleaning, is it trashed?

[kyler021]

So I picked up an expensive EPROM ECU this weekend at The Shootout and noticed a little bit of grime along the connectors so I sprayed it down with some sensitive electronic contact cleaner. Boy, that was a mistake. When it dried, it left white residue all over the board, and I believe it pulled up (a lot) of flux from all over the board.

When I got home I attempted to clean it down with isopropyl alcohol to get rid of the white residue, and it just won't go away. I've probably spent around 2 hours with a soft bristle toothbrush and 91% isopropyl trying to clean it off, when it dries the white residue keeps coming back and it looks like the white residue is getting on the contacts of the soldered points of the components on the board.

Will this hurt the ECU if I try to run it? How should I attempt to clean it off? Should I even bother trying to clean it? Is it too far gone?

I've attached some pictures to this so hopefully you guys will know what I'm talking about. I should also mention that the white residue will wipe off, as I believe it's salt to protect from condensation. I'm mostly worried about the flux/residue touching the solder points. At this point, I wish I hadn't cleaned it in the first place. Any advice on this? I know this is a more general electronics question, but I've searched around and haven't found much other than people telling me to isopropyl and toothbrush, and it seems like that's not helping anymore

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[steve]

It was your attempt to clean it with a solvent that caused this. The conformal coating looks to be wax based.
I believe it's originally applied by dipping the PCB into a bath of hot coating and then allowed to drip as it cools.

You might be able to heat it up and get it to melt but I'd leave it so you don't make things worse. As long as you haven't contaminated the IC socket pins it's likely OK the way it is other than the lack of moisture protection.

 

[kyler021]

It was your attempt to clean it with a solvent that caused this. The conformal coating looks to be wax based.
I believe it's originally applied by dipping the PCB into a bath of hot coating and then allowed to drip as it cools.

You might be able to heat it up and get it to melt but I'd leave it so you don't make things worse. As long as you haven't contaminated the IC socket pins it's likely OK the way it is other than the lack of moisture protection.

Gotcha, thank you for the insight. Everyone says to clean PCBs with IPA or contact cleaner and I've never seen this before on any other PCB. I'm going to drop it off at a computer shop tomorrow to see if they say anything or can do anything about it. Appreciate the help!

 

[steve]

Gotcha, thank you for the insight. Everyone says to clean PCBs with IPA or contact cleaner and I've never seen this before on any other PCB. I'm going to drop it off at a computer shop tomorrow to see if they say anything or can do anything about it. Appreciate the help!

If the board wasn't covered in a conformal coating isopropyl alcohol would be a good choice but for our ECUs I use a Non-Ionic Detergent like Dawn and a soft brush followed by a full rinse and blown dry with compressed air to get all the trapped water out.

 

[FIBA M - EC17PSE]

I use IPA 70% and its never done any wrong doing. Likely just the product you used. Either way it looks bad now so either leave it before its made worse or send it to someone who can work on it and then leave it alone to not create other issues afterwards.

 

[CrackedDSM]

Questions for you that know: could you just add more conformal coating and be fine?

 

[danl]

Questions for you that know: could you just add more conformal coating and be fine?

They sell it in spray cans but it’s not as good as the factory applied stuff. You would want to test a small area to see how it reacts. It has extremely strong fumes, so use outside if possible. Though I feel it’s overkill for this application.

 

[kyler021]

I use IPA 70% and its never done any wrong doing. Likely just the product you used. Either way it looks bad now so either leave it before its made worse or send it to someone who can work on it and then leave it alone to not create other issues afterwards.

Yeah it's gonna go to a computer shop later, fingers crossed that something comes out of it and they can do something about it. After that I think I'll be done touching electronics for a while .

Thanks for all the insight guys! I appreciate it.

 

[CrackedDSM]

They sell it in spray cans but it’s not as good as the factory applied stuff. You would want to test a small area to see how it reacts. It has extremely strong fumes, so use outside if possible. Though I feel it’s overkill for this application.

There's a guy on youtube I watch from time to time, named TronicsFix and he uses stuff that comes in what looks to be a nail polish bottle. I've also seen him use one that's green that you set with a UV light.


Electronics fascinate me. I know nothing about them, but have always been curious. Thanks for the answer!

 

[steve]

There's a guy on youtube I watch from time to time, named TronicsFix and he uses stuff that comes in what looks to be a nail polish bottle. I've also seen him use one that's green that you set with a UV light.

Make sure you not confusing some sort of UV cured solder mask with conformal coating.

 

[CrackedDSM]

*writes in his notebook with a red crayon* conformal coating…solder mask…different.

 

[steve]

On our ECUs the solder mask is the transparent green coating over the top of the copper circuit traces. The conformal coating the the soft waxy yellow coating over the top of everything.