PCB, protection

[Light_Chaser]

I can make printed circuit board easily. But I'm having a hard time trying find a way to make them last longer and protect them from oxidation and corrosion. I have to make a lot of these boards and each board requires a bunch of soldering. Want do my best to make them last.

I gave a UV solder mask paint a try, but it was really hard to put on evenly across my large boards,and over all they just didn't look good. So I had to look into some other options. I found this Conformal Coating that you could spray on. But after a week, my copper started to tarnish in small areas across my circuit board. I put three coats on, allowed each one to fully dry before applying the next one, but it didn't work out for me. I feel like there is more out there that could fix my problem.
I saw this stuff a few days ago called liquid tin. But I couldn't find much information about it other than its used to tin the copper. I didn't want to buy it until I was sure it could be used for my needs. What do you all think I should do?


MG Chemicals Acrylic Lacquer Conformal Coating, 340g (12 Oz) Aerosol Can, Clear
Link to https://www.amazon.com/gp/product/B008OA7178/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

My PCBs are 2" x 9" They only hold LEDs and Resistors
120 5mm LEDs and 40 1/2w Resistors
need to make 12 to 16 of these boards

 

[Minder]

Conformal coating of some kind is usually used for this application, I have never heard of its use for tinning copper?
I have used the one you show in the link and it is for the application you are looking for.
M.

 

[shrtrnd]

Like Minder, conformal coating is the way I do it.
I don't know what you mount your boards in, and it sounds like it's an outdoor application.
My first thought is to find a good enclosure to try to protect the board.
www.mgchemicals.com makes a couple of things you might consider:
4228-55ML Red insulating varnish
4223-55ML Urethane conformal coating
My last, last-ditch thought, if this is some kind of critical failure you're experiencing, and you're not interested
in being pretty or having to troubleshoot and replace parts later, RTV silicone ain't pretty (pretty messy though), but
nothing will get at your board under that stuff.
I like the spray can conformal coatings. Maybe the one you used just isn't good quality.

 

[Chemelec]

Liquid Tin is Available, But Tin Also Oxidizes.

 

[Light_Chaser]

, I have never heard of its use for tinning copper?

talking about liquid tin?

I don't know what you mount your boards in, and it sounds like it's an outdoor application.
My first thought is to find a good enclosure to try to protect the board.
www.mgchemicals.com makes a couple of things you might consider:
4228-55ML Red insulating varnish
4223-55ML Urethane conformal coating

The thing I'm making is a full size light bar like you would see on an emergency vehicle. Enclosure I was thinking about is a flat rectangular plexiglass box with a top that could be removed. Its not going be left out side all the time, only when I need to use it. What ever I find to protect my boards it needs be removable so if I have to replace a LED.. Why I liked the conformal coating I had, I could solder through it.

Liquid Tin is Available, But Tin Also Oxidizes.

Wouldn't it be better for the tin to oxidize than my copper? The thought I had was tin my boards with the liquid tin and use the conformal coating I got now to try keep the tin from oxidizing. Kind of trading one problem for another, but yeah.

 

[Chemelec]

Years Ago, Tin plating was common but Not very Effective, so it is not used much now.
A good Conformal Coating Will protect Both the Copper and Solder Joints.
But Make Sure you REMOVE all SOLDER Flux, Before coating the Board.

 

[Bluejets]

https://www.jaycar.com.au/circuit-board-lacquer-spray-can/p/NA1002

 

[Light_Chaser]

Years Ago,
But Make Sure you REMOVE all SOLDER Flux, Before coating the Board.

I normally use a tooth brush dipped in rubbing alcohol to clean my boards once I got them made.

https://www.jaycar.com.au/circuit-board-lacquer-spray-can/p/NA1002

Looks nice but I feel little uncomfortable buying things from website I don't know.

 

[Bluejets]

1. Jaycar is a well known and respected electronics supplier in Aus.

2. The reference was to show you what was available not necessarily to have you outlay your money there.

 

[Light_Chaser]

What is the main difference between a lacquer and silicone? I saw this one that looks exactly like one I have.

Mine:
https://www.amazon.com/gp/product/B008OA7178/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

Other:

https://www.amazon.com/MG-Chemicals...rd_wg=pOZGC&psc=1&refRID=SW35GK3CZB0Q6A9TH9GG