Conformal Coating on control boards not allowing me to solder

[keeney123]

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

No, I should of said Medical Research Electronic Devices

[RudolfNta]

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

Hi.. as per my experience 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

If the conformal coating was applied correctly it should not cover the solder joints.

of course it should - it should cover everything.
it's to protect the board from chemicals or moisture - solder can rust!

[eccerr0r]

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

Well yes, conformal coating should cover everything (soldermask is probably the main thing that does not cover solder joints... but conformal coating should cover soldrermask) I don't think solder actually rusts or at least it does not rust quickly. However, through hole components tend to have steel leads...

[stj]

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

leadfree solder is 99+% tin, i'v seen it rust outside.

[eccerr0r]

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

It would require a bit of scraping and high temperatures if tin actually "rusted" but tin IV oxide should be off white in color. If you see any red/brown, that's the iron in the through hole pins of many resistors/capacitors.
Tin should generate a passivization layer that makes it react extremely slowly to water much like aluminum.

[stj]

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

leave an old (leadfree) pcb in the garden / on the roof for a month - see what i mean.

[eccerr0r]

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

How about the solder by itself, perhaps just soak it in water? Don't want to introduce copper and steel stuff that's in the rest of the components that are known to corrode.

[stj]

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

maybe.
try it - stick a bit on a window ledge.