Tin plating DIY circuit boards

[John Lyons]

How are you guys plating you copper traces to prevent oxidation? It bothers me to have bare copper traces oxidize.
There is a product called Tinnit by Datak and there is the product Liquid Tin By MG chemicals.
I wanted to get some Tinnit from Parts express by it seems they are out of it. It's a dry powder you mix with water then soak your boards in it and it plates them with tin salts.

Any other products out there and where do you get them.

Thanks

John

[O]

Here's what I've been doing for the past few boards... it's a pain in the neck to do, but I think it gives the boards a little "extra" touch. When the boards are bare and drilled, I place the boards, trace side up into a newspaper that is sitting on top of a piece of foam. I then get some big-headed pins (not the ones with the plastic ball on top, but ones that are used to pin cloth together when making alterations) and stick them on the board. The pins are about the same size as component leads, so you get a snug fit in the holes. The head of the pins are big enough to mask the circumference of the solder that is about to come.

I got some "candy" spray paint from the auto store. Once the boards have been "pinned" I lightly spray a couple of coats on the board. Don't spray it too heavy, otherwise the boards will take a while to dry. Before the boards completely dry, I wiggle the piece of foam from under the board. The pins, without the foam, are really easy to pull out.

If you get the right pins, your results will look really good. I have a picture of a recent booster I made that is coated with transparent red spray. If I can find the pics, I'll upload them.

(If something doesn't make any sense, just ask and I'll try to explain)

[John Lyons]

Hmmm. That's pretty close to a solder mask. I think I'd use a clear spray Laquer so it looks less like a spray painted board.
Good ieda, thanks.

I would still like to go the tinned route though if I can get the stuff. Anyone else?

John

[$uperpuma]

normally once I get everything soldered on, I run some solder on the reamaining traces between components and that tins it right up... it sounds more tedious than it is.. it also helps in spreading out those globby solders that I get sometimes too...

[RedHouse]

I do the opposite, I apply liquid rosin and "tin" the traces with very thin solder, then apply solder-wick to suck up the excess.

It's a lot of work but looks real good.

[Gilles C]

I use MD Liquid Tin when I etch PCBs. It helps when you don't have time to wire them right away as it is the case for me.

I have some PCBs that have been sitting there for years, waiting for me to finish them. It's a luck that I tin them...

Gilles

[Cardboard Tube Samurai]

I don't bother with tinning. I figure the boards are so easy to make anyway, that if worst comes to worst and a board suffers oxidation, then I can simply make another one (and probably mod it some more!!!)

[sfr]

Is the oxidation bad?  I mean, I usually scruff it off before I start putting parts on a board if it's oxidized, (I etch my boards in larger batches and work on them as I find the time - hopefully before somebody puts out a newer revision!)  If I start working on a board, but know I'm not going to get to finishing it until later (usually the offboard wiring) then I tin the remaining pads with some solder just to make it easier to get in there later (harder to scrub the oxidation of a board that's mostly populated) 

But after I build the pedals, is oxidation a problem then?  Will it change things?  Or is this just so stuff *looks* proper?

[bancika]

I use some kind of plastic spray. It's intended for electronic use. Looks like lacquer and forms plastic like coat. But the great thing about it is you can solder through it, it doesn't burn, get black or anything....so I don't have to put masks or something.

[John Lyons]

Bancika
Is this spray you use a "conformal"  coating?

I just want to make a more professional board that will not oxidize before I or others start soldering on it. (and aftereverythigs done as well)
Some of the circuits I do are pretty complex so I don't want to spend all day tinning them with the iron. On a simple circuit this would be a way to go.

John

[bancika]

I don't know what "conformal" means
Also, I have no idea if this spray can be bought any more. It's very old bottle a friend gave me. It's real time saver

[Pushtone]

How about just spraying the trace side of the board with clear coat after all the soldering is done and tested?
No one mentioned it so I wondering if it's a bad thing to do?

[bancika]

before getting this spray I used my girlfriend's nail polish to cover all traces after soldering. Basically it's not a problem but if you wan't to desolder something lacquer will smell pretty bad and turn black. If you have patience take 20 minutes and do it with nail polish, it has small brush so you can do it precisely. Just skip solder joints...

[sfr]

I had seen a DIY wave soldering type rig online once - I'll have to see if I can find it again - wouldn't something like that help for tinning boards?

[R.G.]

1. Oxidation does not materially hinder circuit performance, except for certain high frequency or high impedance circuits. I have boards that I made over 30 years ago that look terrible, but they work fine.
2. The Tinnit stuff is fine, produces a nice 3-4 microinches of tin - that then oxidizes. The Tinnit liquid stuff makes soldering easy at first, but harder later. But I never let one wait long enough for it to be a problem.
3. Tin-lead solder coating is nice. Solder oxidizes too, but it's still solderable with flux. But it's a pain with a soldering iron
4. Spray paints that you can solder through are nice. Experiment and find a brand you like. You'll kick yourself for using anything except clear if you ever have to do any debugging.
5. Low volume single sided boards done by the pros used to be roller tinned. Roller tinning was done by having a pot of molten solder with a big metal wheel turning slowly in it. The solder heated the metal roller up to soldering temp and the wheel picked up a smooth coating of molten solder. The boards were painted with flux, then passed over the surface of the roller. They picked up a smooth, thin layer of solder on the copper from the surface of the wheel.
6. There is an easy (-ish) way to do something like roller tinning at home. But you have to be a workshop kind of guy. Go to a hardware store and get a suitable piece of brass plumbing pipe. I use 4" long, 1" diameter. Hacksaw the threaded parts at then end off. Thin copper pipe will not do - you want mass. Drill a hole into the center of the side of the pipe but not all the way through both sides. The hole should be the right diameter to be tapped for threaded rod. Tap it, then run in a threaded rod, and lock this with a locknut or lockwashers and locknuts on the outside. The threaded rod needs to be at least 6-8" long. Use the threaded rod to put an insulating handle on - you're going to hold that part. You now have a handle and the  pipe makes a T across one end.

When you're done with construction, sand the outside of the pipe  on the side opposite the handle smooth. Chuck the handle in a vise, pipe end up, and paint the round smooth surface with flux. Hold a propane torch at one side pointing through the hole in the middle. Heat the inside of the pipe until the flux starts running and smoking, and then run solder onto the surface of the pipe. It should immediately wet the whole surface. You now have a tinning tool.

To tin a board, lay the board on heat proof surface, ideally against an edge that will keep it from slipping. Paint it with liquid flux. Heat your tinning tool up to solder temperature, coat it with solder, then run the smooth surface across the tinned board. If you do this well - and it may take some practice - you will get a nice, smooth tinned surface.

[MR COFFEE]

I just want to make a more professional board that will not oxidize before I or others start soldering on it. (and aftereverythigs done as well)
Some of the circuits I do are pretty complex so I don't want to spend all day tinning them with the iron.

If all you want is to prevent oxidation until you are ready to solder up the board, you don't need to go to the trouble and expense of tin plating. Just coat the trace side with liquid rosin flux and let it dry. Prevents oxidation for years. Dip a small piece of a thin rag in flux and wipe it on.

I have been disappointed by the immersion tin-plating solution - it goes bad after a while and makes a not-too-solderable coating.

[John Lyons]

I was doing some boards last night and I soldered all the traces with a thin coat. Took lest time that I thought it would. I need to get a solder wick but my desoldering bulb did an ok job. I guess I'll go this route and look into the flux to keep boards fresh if I have to store them for any time between working on them.

John