How you protect pcbs from oxidation?

[ubaid88]

Please suggest some cheap method protecting pcb from oxidation. That are easy to adapt by diyers like us. I sometime clearcoat them with lacquer. But they are not gud, if u want some mods in your circuit.

[pazuzu]

desiccant bags and and sealed containers?

you are talking about storing them or preventing oxidization after the build?

[Mark Hammer]

Personally, I take a cotton swab, smear the entire drilled and buffed PCB with liquid flux and tin the whole thing.  Although solder will also eventually oxidize if not protected, it will oxidize much more slowly than bare copper.  Since I am prone to mods that involve tacking on extra components on the copper side, I find that tinning the entire surface gives me a bigger palette to work with than if I merely solder the pads and everything else gets "obstinate" when it comes to soldering in 3 months.

I do this regardless of the size and complexity of the board.  But it takes a long time, you say.  Sure, and so does trying to get that damn parallel resistor/cap to solder properly to the board 3 months later.

[ubaid88]

desiccant bags and and sealed containers?

you are talking about storing them or preventing oxidization after the build?

Prevention of from oxidizing after building them. I dont about you guys. But the where i live in, got very high level of humidity because of sea. And that poisonous for copper. It can easily damage the thin copper tracks. If its exposed for a long time.

[pazuzu]

clear coat?

[danielzink]

MG Chemicals Tinning solution.....

http://www.alliedelec.com/search/productdetail.aspx?SKU=6610091


Dan

[davent]

Edit. Like Dan said and here's a description of the process someone put up on the web.  http://www.delorie.com/pcb/liquidtin/

dave

[SonicVI]

+1 on the Liquid Tin.  It seems expensive but you can use it over and over again so even the small size bottle will last a long time.

[OnLyTNT]

Get some natural resin (not synthetic one). It looks like small, yellowish, transparent rocks. Also get some cellulosic thinner. When you put the resin into the thinner it will dissolve easily. You can adjust the mixture according to your application. If you use much thinner it will take more time to dry, less thinner means thicker coat. Yes, as you understand from the last sentence, you're gonna cover the copper side of your PCB with that chemical after etching it.

When its dry, soldering will be much easier, it protects solder tip and after soldering it will look very shiny. You wont need any solder paste. It doesn't need to be cleaned after the process. Finally, it protects the copper very well. If you want to get rid of it, just wipe/brush with some thinner again.

It's the cheapest and best way ever.

[ubaid88]

Get some natural resin (not synthetic one). It looks like small, yellowish, transparent rocks. Also get some cellulosic thinner. When you put the resin into the thinner it will dissolve easily. You can adjust the mixture according to your application. If you use much thinner it will take more time to dry, less thinner means thicker coat. Yes, as you understand from the last sentence, you're gonna cover the copper side of your PCB with that chemical after etching it.

When its dry, soldering will be much easier, it protects solder tip and after soldering it will look very shiny. You wont need any solder paste. It doesn't need to be cleaned after the process. Finally, it protects the copper very well. If you want to get rid of it, just wipe/brush with some thinner again.

It's the cheapest and best way ever.

Thanks you. Look worthy to try. Its easy and cheap.

One question.
Pcb must be coated before soldering or after soldering?

[potul]

I use a spray to protect my pcbs. I don't remember the name of it, but I bought it in an electronics shop. It protects from oxidation but allows re-soldering if needed. When I'm back at home tonight I will see if I find it and give you the name.

Regards

[darron]

yeah... the acid on your fingers from touching the board tarnishes them badly.

ever electronics shop i go to has circuit board lacquer with a nitro base that you can solder through.

so my process is to make the board, brush them back with fine steel wool, then solder-through-lacquer them, THEN drill them. if you drill them first then it can leave spurs that the steel wool can catch on and rip up traces. sigh....


having said that last night i ordered a container of tinning crystals, sounds like that would be the best thing. a can of PCB lacquer would only cost like $10 though.

edit: far out.. just followed the link for that tinning liquid. now i feel like i've been ripped off by farnell!!

[OnLyTNT]

Get some natural resin (not synthetic one). It looks like small, yellowish, transparent rocks. Also get some cellulosic thinner. When you put the resin into the thinner it will dissolve easily. You can adjust the mixture according to your application. If you use much thinner it will take more time to dry, less thinner means thicker coat. Yes, as you understand from the last sentence, you're gonna cover the copper side of your PCB with that chemical after etching it.

When its dry, soldering will be much easier, it protects solder tip and after soldering it will look very shiny. You wont need any solder paste. It doesn't need to be cleaned after the process. Finally, it protects the copper very well. If you want to get rid of it, just wipe/brush with some thinner again.

It's the cheapest and best way ever.

Thanks you. Look worthy to try. Its easy and cheap.

One question.
Pcb must be coated before soldering or after soldering?

I suggest you to do it before soldering. As I mentioned in my first message it has many advantages.

But if you have a PCB already soldered, you can always apply coating to protect the copper surface. Even you can apply resoldering to make sure the solder last longer.

[davent]

Something else i tried before getting Liquid Tin is Testor's Candy Green lacquer from a model shop. You can solder through it and it leaves you with a board that looks sort of like it has a solder mask on it.

dave

[sixstringphil]

I tried clearcoating a board a while back with the same Krylon clear I used on enclosures. It actually seemed to work well. I was still able to solder, but I wondered if the fumes might be super-nasty, so I haven't tried it since. I guess it would work well if you had soldered everything onto the board and didn't plan to do alot of modding later.

[R.G.]

PCBs used to be roller-tinned. This was a process where a steel roller was coated with a layer of solder like tinning a soldering iron - which it became.

The roller was rotated above and just dipping into a pot of molten solder. The roller picked up both heat and solder from the pot to maintain a layer of molten solder on the roller.

PCBs fresh from etch were painted with liquid flux, then moved across the rotating roller so that it heated the copper spaces and deposited a thin layer of solder. Bingo, solder-tinned PCB.

I adapted this process to DIY boards this way. You don't need either a pot of solder nor a big heated roller setup for one or two boards. What you need is an inches-wide soldering iron. I went to Home Depot and bought a 6" long piece of 3/4" brass pipe, a 12" length of all-threaded rod, some matching nuts, washers, and lock washers, and a bit of dowel rod of 1" diameter. Back home I drilled a hole in the middle of one side of the brass pipe. I tapped this hole to take the threads in the threaded rod, then screwed the rod into the hole and locked it into place with a lockwasher/nut. I drilled a hole lengthwise through a 6" length of the dowel, stuck the dowel through it and held it in place with nuts/lockwashers on both ends. It's a heat-resistant handle. Result is a handle with the brass pipe across the end of it like the letter "T".

Then I sandpapered the side of the brass pipe opposite the handle until it was smooth and shiny, painted it with liquid flux, and heated it by directing the flame of a propane torch through the middle of the pipe. When the flux started flowing, I touched solder to the fluxed area, tinning the brass pipe with solder. In a couple of minutes, I had a smooth, shiny layer of molten solder on the whole face of the pipe.

Now I can tin PCBs. Paint the PCB with liquid flux, and the brass pipe. Lay the PCB on a heat-proof surface, flux/traces side up. Fire up the propane torch, and holding the handle of the coating rig by the dowel/cold end, direct the flame through the middle of the brass pipe. This gives better control than trying to heat it over a fire or some such and keeps the solder coating clean. When the solder flows, swipe the pipe across a slightly dampened sponge or disposable towel to get the crud off, load it up with some more solder, reheat if needed to get a good, liquid coating, and then run the brass pipe, solder side down, flat on the fluxed PCB traces. The brass pipe/solder retains enough heat to heat the PCB traces and flow solder onto them, tinning the entire surface in a single swipe ... if you're good. It may take some practice. If you have to make repeated swipes to correct things, let the PCB get cool between times because the large heat source in the brass pipe can overheat and lift traces if you dawdle, reheat and swipe several times, or press too hard. If things are done properly and you have a good touch, it's like magic - one swipe tins the entire PCB.

You can still spray lacquer, etc. on it as a solder mask, but the pads will now solder nicely if you leave it sitting for years. Copper will tarnish if not protected.

If you have a copper-only PCB, you can protect it by spraying it completely with lacquer. When you want to solder, just swipe it off with lacquer thinner. You can do exactly the same with shellac, which can be swiped off with alcohol instead of the nastier lacquer thinner.

[tranceracer]

I tried clearcoating a board a while back with the same Krylon clear I used on enclosures. It actually seemed to work well. I was still able to solder, but I wondered if the fumes might be super-nasty, so I haven't tried it since. I guess it would work well if you had soldered everything onto the board and didn't plan to do alot of modding later.

I use Krylon Crystal clear and it works well, just add some flux to the pad when you're ready to use it and you can solder right thru the clear, .  Fume emissions are about the same as flux fumes either way i just have a fan on low to blow the smoke away.  I just use a very thin coat of clear.  Only need to spray 1 light coat.

[Minion]

I use a spray on Nitrocelulose , You can even solder through it if you need to solder a joint over it again .......

[head_spaz]

Something else i tried before getting Liquid Tin is Testor's Candy Green lacquer from a model shop. You can solder through it and it leaves you with a board that looks sort of like it has a solder mask on it. - dave

Like davent, I'm also using Testors' paint to GREEN my boards as well. It gives it a very professional "solder mask" look, and it's
easy to melt right thru it when soldering. I like the paint better than using tin-it plating.
But I couldn't find the transparent candy green color in laquer, so I'm using enamel. My only complaint is that enamel takes
quite awhile to dry.
I also iron on a toner "silkscreen," and then iron over it using Pulsar's White Pigment Toner Foils to color the lettering.
The end result is fantastic, lookin just like pro made PCBs. The toner foils are coated with a colored pigmentation. When you
iron it over the toner, the pigmentation melts into the toner, coloring it to perfection. Looks like silkscreen. They even have
metallic colors now, but I haven't tried them because they might be conductive.
(Pulsar invented the toner transfer method, and the decal processes we've been using)

Anyway... here's the paint part numbers in case anyone is interested.
TRANSPARENT CANDY GREEN - 3 OZ. SPRAY CAN ENAMEL
SKU# 1601 Enamel
USD$ 4.94

When I etch "fancy colored" pcbs, I often use clear lacquer to protect the copper from corroding. The lacquer dries super fast,
and it's no problem to solder thru it afterwards. Hardly know it's there.
I often clear coat my boards after they're fully assembled too, using their Wet Look clear lacquer. This protects the project from
moisture and helps to prevent the wires from corroding at the solder joint.
The best part is that it gives the finished board a nice polished look. Fresh and sparkly clean looking... like it's ready for the front
page of a magazine. Try it... you'll like it.

Wet Look Clear Coat One Coat Lacquer
SKU# 1834M
USD$ 4.99

[Paul Marossy]

Something else i tried before getting Liquid Tin is Testor's Candy Green lacquer from a model shop. You can solder through it and it leaves you with a board that looks sort of like it has a solder mask on it.

dave

That looks nice. The only thing is that spray enamel takes so darn long to dry!