Conformal Coating on control boards not allowing me to solder

[VMWkmdealer]

i am an appliance tech specializing in digitally controlled washing machines, and am looking to replace This blown capacitor



Problem is, the board has a coating on the backside of it which will not allow me to solder or desolder the bad cap i want to change, ive been hunting up and down, and have come up with a conformal coating remover pen or micro abrasive blasting to be the only methods to removing this coating

and thats why im posting this thread, i intend on staying because im very interested in soldering and learning about this stuff

[keeney123]

Re: Conformal Coating on control boards not allowing me to solder

i am an appliance tech specializing in digitally controlled washing machines, and am looking to replace This blown capacitor



Problem is, the board has a coating on the backside of it which will not allow me to solder or desolder the bad cap i want to change, ive been hunting up and down, and have come up with a conformal coating remover pen or micro abrasive blasting to be the only methods to removing this coating

and thats why im posting this thread, i intend on staying because im very interested in soldering and learning about this stuff

You do understand that a lot of boards use solder with no flux in it so when you desolder a part use need to apply liquid flux first before you can heat up the joint. If the conformal coating was applied correctly it should not cover the solder joints. If it is covering the solder joints and you only need to desolder one cap you can use an X-acto knife to scrape of the coating just on the solder joints to get to the solder connection.

[stj]

Re: Conformal Coating on control boards not allowing me to solder

try IPA or white spirit.

[comptek]

Re: Conformal Coating on control boards not allowing me to solder

fiberglass scratch pen £2 on ebay

[VMWkmdealer]

Re: Conformal Coating on control boards not allowing me to solder

You do understand that a lot of boards use solder with no flux in it so when you desolder a part use need to apply liquid flux first before you can heat up the joint. If the conformal coating was applied correctly it should not cover the solder joints. If it is covering the solder joints and you only need to desolder one cap you can use an X-acto knife to scrape of the coating just on the solder joints to get to the solder connection.

No i didnt know that, but ive been reading and researching and now see one key thing im missing Flux......


But the board is pretty coated in this stuff, the joints appear to be coated with it, the same shine on the board is covering the solder joint

[VMWkmdealer]

Re: Conformal Coating on control boards not allowing me to solder

hows the Conformal coating remover pen from Mouser Electronics?, i see theres a few Pens which claim to remove the coatings, but im debating if theyre safe or not, as i have no experience with this

[keeney123]

Re: Conformal Coating on control boards not allowing me to solder

So if you are only removing one cap then you can just scrap the coating off.

[stj]

Re: Conformal Coating on control boards not allowing me to solder

some coatings are hard, some are soft.
you cant scrape a lot of them - you need to disolve them.
i get this every time i need to work on a honda ecu

[VMWkmdealer]

Re: Conformal Coating on control boards not allowing me to solder

i ordered a fiberglass scratch pen just to see if that would work, the coating seems very hard and applied to the entire surface of the board up to around the very edges, i just want to make it an efficient process, because i will be replacing ALOT of them once i get past this coating ordeal, of course im gonna practice on quite a few boards before officially putting them in machines

[VMWkmdealer]

Re: Conformal Coating on control boards not allowing me to solder

the fiberglass scratch pen was an utter failure, while messing with the boards, i discovered one version of the boards is light green versus dark green as pictured, and i can actually flake off the coating from the other board that is light green

the scratch pen did little to nothing to the coating on both boards, thats why i grabbed a razor blade and figured id try a few things out

i ordered some conformal coating remover pens to see if that would help, im not finding much information on how to remove this coating

and its probably that hard of a coating Because it is used for a device which contains and works with water

[diif]

Re: Conformal Coating on control boards not allowing me to solder

Perhaps some heat applied will soften it to scrape it off ?
A little research shows different types of conformal coating and different chemicals to remove them depending on type.

[VMWkmdealer]

Re: Conformal Coating on control boards not allowing me to solder

so three methods tried, three methods failed.... fiberglass scratch pen is out of question, Conformal coating remover pen is out of the question, and heat hasnt done much of any help

the farthest ive gotten is with a razor blade, but i had trouble doing it

[stj]

Re: Conformal Coating on control boards not allowing me to solder

acetone on a cotton bud maybe

[keeney123]

Re: Conformal Coating on control boards not allowing me to solder

Conformal coating is no picnic. It is often toxic to breath. The chemicals used to take it off can also be toxic to handle and breath. The coating should only be less then the thickness of a human hair applied on the board. If you are going to do a large area on a board it is best to find a manufacturer with a vat for these chemical process or a micro sandblaster with an enclosed hood. If you are doing a few pads for soldering a scalpel will work. If you use heat to remove it, either a soldering iron or heat gun, you will need a hooded exhaust fan that has a vent to the outside with a filter to capture some of the toxins. Most of the conformal coatings are urethane. It is hard and resistant to chemicals. I believe today they they use conformal coatings over the solder joints because the joints are so close together that any dirt can interact with the signal. This is the price of miniaturization. Certain epoxies have the capability of encapsulation like urethane with even higher resistance values then urethane, but they may not be as cheap.

[diif]

Re: Conformal Coating on control boards not allowing me to solder

The board I worked on that had conformal coating was done to waterproof Keeney.

Maybe some MEK on a cotton bud would help remove,

[VMWkmdealer]

Re: Conformal Coating on control boards not allowing me to solder

MEK???

yes this coating seems invincible, i learned how to solder (not perfectly) and am anxious to get into swapping the caps on the boards i wish to fix, but this coating about has me ready to quit, The most effective thing i can think of is the micro media blaster which isnt cheap, but if its something im going to be doing alot of, i dont mind buying it

[keeney123]

Re: Conformal Coating on control boards not allowing me to solder

The board I worked on that had conformal coating was done to waterproof Keeney.

Maybe some MEK on a cotton bud would help remove,

So you were using it in water?

[diif]

Re: Conformal Coating on control boards not allowing me to solder

So you were using it in water?

NO, it was the controller for an electric mobility scooter, it lived by the back wheels inside an aluminium case sealed with a gasket.

I half scratched the coating, half melted it with my iron, was a bit messy, but my friend wasn't concerned with looks.

[keeney123]

Re: Conformal Coating on control boards not allowing me to solder

My friend lives in a powered wheelchair. When she first drove it in the rain it quit working. It left her 0.5 miles from her home. Later on the techs told her to put a bag over the control arm. To me the solution is to make the container of the board water tight so the water does not get to the control board.
Why I said the comformal coating is dirt etc. is because I know very well what the elements can cause in sensitive electronics. I worked for a company call World Precision Instruments.They made research electronic devices. One of my jobs was making special probes that operated down to 1 X 10-14 Amperes. The whole probe was the size of a ones little finger. They consisted of 7 or so parts on a circuit board. That had to slide down inside a gold plated container and that container slide down another gold plated container. None of the parts on the board could touch the container. Seven wires needed to be attached to the circuit board. After all this they went into a mold and had to be potted with special high resistance epoxy. Cleaning the board were critical. Most cleaners in the electronic industries would not work. When I took over this position these probes had only a 30% success rating on ever making it out of the company. After I took over that went up to 95%. I worked for this company from 1992 to 1994.

[stj]

Re: Conformal Coating on control boards not allowing me to solder

is that for the oil drilling industry by any chance?