The green stuff on a PCB

[The Master]

Hi. I have a few questions about the green stuff that goes on the underside of a PCB over the tracks.

First of all whats it called?

Is it possible to put it on a home made PCB?

[duncan303]

Hi

the green stuff is referred to as Soldermask.

Is it possible to put it on a home made PCB?

it is possible there are various products, but if you are not wave soldering(essentially dipping the whole board in molten solder) it could depend on the reason you wish to apply a coating as there could be something better.

Duncan

[mackrackit]

I always thought the green stuff was mold

If you are just wanting to seal the board from corrosion when it is finished, a can of clear spray paint works well. Clear finger nail polish for small jobs or touch ups.

[The Master]

wow, you guys replay fast on here.

I want to apply it because of corrosion, making soldering easier (the solder wont run down the track like it does when its bare) and it prevent things accidentally touching tracks (things include screwdrivers, metal filings, wires and fingers :P)

I would like to apply it before soldering because making soldering easier is one of the reasons i want to do it. The problem i see is how do i keep the pads clear?

Clear spray paint sounds like a good idea.

I have some stuff called "PCB Laquer" i think. Someone gave it to me a while ago and siad it was something to do with protecting PCBs but ive never used it. Is that anything similar?

[mister_e]

When i do some home-made PCB, i use Liquid Tin (MG Chemical 421-500ml)

And then i solder my components on, clean the board with Isopropyl alcohol to remove flux, and that's it.

You can still apply some clear varnish on if you want. Clear spray would do the job.

[duncan303]

No hanging about here!

well fair enough you have listed all the advantages of a soldermask, except cosmetic so that makes it easier.
ruffling about in her handbag you could end up with any colour nail varnish

cheap and cheerfull you could leave the bare copper untinned and let it oxidise for a few days, then get a standard pencil rubber and clean just your annular rings and pads etc. if you do not add extra flux you will find that the oxidation acts as a sort of mask, then when you have finished populating use your acrylic laquer to spray the whole PCB.

it sounds also a bit like you may be overdoing it with the solder if it has decided to run off down the tracks , try getting in the samllest guage solder you can. also do you have enough heat in your iron tip and are you using lead free?

I should be able to remember what you could use to speed up the oxidation, would hydrogen peroxide on some cotton wool placed in a sealed jar with the board do it? or is it sliced potatoes?

There are some "conformal coatings" that allow you to rework I think electrolube do one but I am not sure.

Are you mounting SMD's? one trick I have used that may help is to tidyup using thin solder braid that can leave tidy pads especially in a very restricted area and due to extreamly small pitches.

Don't know if this is helping so I will stop

Duncan

[duncan303]

Hi Luciano

I have some of the SK10 I found it really sticky as if it never properly dried out, it worked well as a flux and to protect against oxidation but it just kept attracting dust.

I can remember having a hell of a time getting it off, the only product that seemed to work effectivly was Chemtronics Flux-Off.

Duncan

[mackrackit]

wow, you guys replay fast on here.

I am at work...so I am keeping busy

I have some stuff called "PCB Laquer" i think. Someone gave it to me a while ago and siad it was something to do with protecting PCBs but ive never used it. Is that anything similar?

Same idea. Me, I like to "tin" the boards first, makes surface mounts easier. Then some scotch tape across the pads before I spray paint (if I paint first). Then when the board is tested and ready to go I will spray the whole thing again. I have gotten to these maybe extremes because most of my stuff ends up in very high corrosion places.

I do a lot of one time stuff, so I do not very often use an outside service to make the really nice boards. Takes some time though to make a board that will last.

I think sparkfun.com has an article about solder masking.

[Luciano]

Hi,

I use that:

http://www.crcind.com/wwwcrc/tds/TKC...20FLUXSK10.htm


http://www.crcind.com/csp/web/ProdDi...XG003674297023

CRC Industries UK Ltd
Ambersil House
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Castlefield Industrial Estate
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ENGLAND
Phone : +44 1278 727200
E-mail Address : [email protected]

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Best regards,

Luciano