The green stuff on a 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

[The Master]

So this laquer stuff. Did i understand correctly that it works as both a protective layer and soldering flux so i could spray it over the whole board and solder ontop of it? (something like that anyway)

Whats an SMD? Probably not because i dont know what they are.

How do you "tin" a board and what is scotch tape?

I have 2 soldering irons. the old one is the best although the tip is about a sharp as a balloon and the new one (brand new!) doesnt appear to heat up enough to melt the solder properly so i dont use that so often. I dont know if my solder is lead free (ill have to check when i get home)

Just having a look on SparkFun.com now to see if i can find that article

Edit: If any of these questions have already been answered then i didnt understand it

[mister_e]

So this laquer stuff. Did i understand correctly that it works as both a protective layer and soldering flux so i could spray it over the whole board and solder ontop of it? (something like that anyway)

Protective layer only. You want to spray your board at the end unless you will smell the burned varnish all the time.. not a good idea.

Whats an SMD? Probably not because i dont know what they are.

Surface Mount Device. they came in various flavors.
http://en.wikipedia.org/wiki/Surface-mount_technology

How do you "tin" a board and what is scotch tape?

There's several way, i use the Liquid Tin i suggested above. Once your PCB is done, you just drop it in the liquid for ~1 minutes... then you clean it with hot water and let it dry for few minutes... then you solder your parts on.

Or you can use your iron, apply solder on all tracks, then remove the "excess" (not sure of the translation... sorry) with solder wick (desoldering braid). What's desoldering braid? http://www.mgchemicals.com/products/braid.html

Scotch tape... something like that

[mackrackit]

Laquer is not a flux. Can not solder through it.

SMD= surface mount device

Scotch tape= generic for the clear tape that you might use on a package (birthday, Christmas)

I tin a board by fluxing the traces and melting a very little bit of solder on before I place the part. The are other ways though.

Dull iron, get a file .

[duncan303]

So this laquer stuff. Did i understand correctly that it works as both a protective layer and soldering flux so i could spray it over the whole board and solder ontop of it? (something like that anyway)

The SK10 to which I was refering to is NOT the same as the laqur that you might have.


Your product could probably be sourced from Maplin:
PCB Lacquer
• Fast drying acrylic coating
• Acid and alkali resistant
• Multi application
• Seals printed circuitry
• Use for over-lacquering of metal and paintwork
• Ideal as a waterproof coating for maps and technical documents
• Supplied in a 200ml can

Is this the same product it would say Maplin on it?

It is a bit of a nightmare as there are more "service aids" stuff in aerosols and bottles than one man can reasonably want or use.




The tinning I use is
Seno Immerse Tin 90g for 1ltr £11.50 from megauk, mix it yourself as it has a short useable life in weeks, It is extreamly poisonous, not really to be chucked down the drain! as with almost anything to do with PCB production these days.


Whooaa this thread is sure am moving

Duncan

[The Master]

I will check out the laquer when i get home. I cant remember where its from.

So, i cant put normal laquer on the PCB before soldering. Is it fine to do it if somehow it doesn touch any of the pads?

Ive always been told never to file a soldering iron because it wont work properly. Something about the heat not being focused to the point or something. Ive not seen anywhere that sels the kind of tips the old one uses. I could do with a new really expensive one from Rapid that will work well.

If you cant put it down the drain then where does it go?

I dont have any Surface Mount Devices but i do put components on the underside of the PCB to save space sometimes

I tin a board by fluxing the traces and melting a very little bit of solder on before I place the part. The are other ways though.

Traces? Should that have been "tracks"? Do you mean you flux the whole thing but only put a bit of solder on the pad or do you put solder on the whole thing too?

[duncan303]

Get a tip instead unless the soldering process is not going to work really good. IMHO.

This could be a big subject about tips etc, personally I never touch my tips with anything other than solder, I used to wipe them on a pad using pure water from the reverse osmosis kit, but I do not even do that now I only use Weller wool balls.

Tips are pretty expensive. anything I can do to extend thier life is worthwhile.

working on say an 0402 series without a decent iron is a total non starter.

However making sure that the tip is in "proper thermal contact" with the heating element is a daily good housekeeping task, even an oxidation layer can make a differrence, I do use several tips during a session so try I to make sure even little bits of grit get in.


Just the thought of somebody coming anywhere near my tips with a rasp file is well and truly an

Duncan

[Luciano]

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

Hi Duncan,

After I apply the spray SK10 on the PCB, I bake the PCB for about 10 minutes in a preheated
pizza oven at about 100°C. After this treatment, the SK10 film on the PCB is dry.

Best regards,

Luciano

[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
Wylds Road
Castlefield Industrial Estate
GB-BRIDGWATER. SOMERSET TA6 4DD
ENGLAND
Phone : +44 1278 727200
E-mail Address : [email protected]

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Best regards,

Luciano