Prevent board from oxidizing

[Gargaman]

Well, no time for searching..
I decided to apply a clear coat on the copper side of the board, to prevent oxidizing.
I did that after soldering and testing the board to make sure its rocking.
I was aware that I would not be able to take measures with the multimeter after the coat,
but the fact is that all the wires are shorting after the clear coat...
What I am missing?
I started to apply a remover after that, the continuity test is showing a little resistance, but some wires are still shorted.
Any suggestions?
Thanks

PS.: I searched a little and I found some products that may do the job. Meanwhile I read the composition of the 'clear coat' that I've used; will these components lead to short connections? = metallic pigment, titanium dioxide, aluminum silicate

[davent]

Well, no time for searching..
I decided to apply a clear coat on the copper side of the board, to prevent oxidizing.
I did that after soldering and testing the board to make sure its rocking.
I was aware that I would not be able to take measures with the multimeter after the coat,
but the fact is that all the wires are shorting after the clear coat...
What I am missing?
I started to apply a remover after that, the continuity test is showing a little resistance, but some wires are still shorted.
Any suggestions?
Thanks

PS.: I searched a little and I found some products that may do the job. Meanwhile I read the composition of the 'clear coat' that I've used; will these components lead to short connections? = metallic pigment, titanium dioxide, aluminum silicate

Yes.

Why does clearcoat have pigment in it, that's not clearcoat that's paint. Watch out for carbon black too.

Try a mist coat of clear lacquer.
dave

[Rob Strand]

You can buy clear lacquer for PCBs.   There's a few types.  You want the basic clear pcb lacquer not the conformal coating stuff.

[anotherjim]

I think it's the polyurethane clear gloss lacquer you want. You can solder through it if you have to. The Poly' isn't as common as it once was - acrylics have taken a lot of the DIY/Decor market.

[Gargaman]

All right!
Tks for the tips

[Mark Hammer]

Whenever I etch a board these days, I immediately wipe it with liquid flux after the resist is removed, and tin the whole thing with solder, then clean the flux off with methyl hydrate, before I drill a single hole.  Works like a charm.  Doesn't take much solder, either, and the flux helps that tiny bit spread easily.  Solder will eventually tarnish, but not nearly as quickly as exposed copper.

[Marcos - Munky]

Whenever I etch a board these days, I immediately wipe it with liquid flux after the resist is removed, and tin the whole thing with solder, then clean the flux off with methyl hydrate, before I drill a single hole.  Works like a charm.  Doesn't take much solder, either, and the flux helps that tiny bit spread easily.  Solder will eventually tarnish, but not nearly as quickly as exposed copper.

+1 to that. I do it too. Just be sure to do it before drilling holes, as pointed by Mark.

[Gargaman]

Whenever I etch a board these days, I immediately wipe it with liquid flux after the resist is removed, and tin the whole thing with solder, then clean the flux off with methyl hydrate, before I drill a single hole.  Works like a charm.  Doesn't take much solder, either, and the flux helps that tiny bit spread easily.  Solder will eventually tarnish, but not nearly as quickly as exposed copper.

+1 to that. I do it too. Just be sure to do it before drilling holes, as pointed by Mark.

Even if theres a big ground plane you cover with solder?
After cleaning the flux, you dont apply anything to protect the solder?
I started to print small traces and cover the traces with solder, assuming that it will be more resistent and less prone to break than the copper itself. But I thought it wasn't economic.
Marcos, can you point these products in Brazil: flux and clean lacquer pcb?
I'm having trouble to translate and find the right lacquer.
I think this guy is using 'breu' and 'alcool isopropilico' to make his own flux.
https://www.youtube.com/watch?v=MY4QdROhu6w

[Gargaman]

I'll try this out:
- Etch the board (I'm drilling before etching)
- Apply flux all the board, this > https://www.baudaeletronica.com.br/fluxo-para-solda-500ml.html
- Populate
- Aplly lacquer, this > https://www.baudaeletronica.com.br/isotec-verniz-protetivo-170-g-300-ml.html
Sound good?
I tried to find a non-conformal as pointed by Rob, but wasn't lucky

PS. I was perfuratng a bit out of center so I use a pen to make up, then etching after drilling. But now I got some skills to perfurate it right and maybe I should switch the order and etch before drill

[davent]

I'll try this out:
- Etch the board (I'm drilling before etching)
- Apply flux all the board, this > https://www.baudaeletronica.com.br/fluxo-para-solda-500ml.html
- Populate
- Aplly lacquer, this > https://www.baudaeletronica.com.br/isotec-verniz-protetivo-170-g-300-ml.html
Sound good?
I tried to find a non-conformal as pointed by Rob, but wasn't lucky

PS. I was perfuratng a bit out of center so I use a pen to make up, then etching after drilling. But now I got some skills to perfurate it right and maybe I should switch the order and etch before drill

With any of the lacquers i've used whether water based or spirit based a light coating of the bare copper after etching will protect the copper from oxidizing. No issues at all in soldering to the lacquered copper and i've had boards sit for a few year before populating and soldering and the lacquered boards solder like to freshly etched, newly exposed copper. Works great, quick and easy to do, very economical.

Etch before drilling and if the hole center of the etched pads is the right size, it can help the drill bit self center in the etched pad, very light touch on the drill advancement and the board gently secured/held.
dave

[Mark Hammer]

Even if theres a big ground plane you cover with solder?
After cleaning the flux, you dont apply anything to protect the solder?

Yes.  Especially big ground planes.  The reason is that if I am going to add any more controls or jacks, I'll need a good easy place to attach ground wires.  Solder covering the ground plane lets me connect a ground wire o any part of it.

And no, I do not cover the solder with anything.  Can it possibly oxidize/tarnish?  Yes, but it will take several years.  It's my own preference.  No obligation on anyone else to copy me.

[iainpunk]

this is a great cautionary tale, haha

cheers

[marcelomd]

+1 for tining the whole thing before soldering. Protects the board and helps with the solder. I do it with perfboard too.

I just "draw" the traces with a bead of solder. On planes/perfboard I use a strip of copper braid saturated with solder.

[deadastronaut]

''With any of the lacquers i've used whether water based or spirit based a light coating of the bare copper after etching will protect the copper from oxidizing.''


yep, ive done this with home made pcbs, a shot of clearcoat, and you can still solder through it no problem..

and retain the shine/protection years later...

[PRR]

...Can it possibly oxidize/tarnish?....

If it does, a touch of the iron will break it up. (Unlike copper oxides.)

[Marcos - Munky]

Even if theres a big ground plane you cover with solder?
After cleaning the flux, you dont apply anything to protect the solder?
I started to print small traces and cover the traces with solder, assuming that it will be more resistent and less prone to break than the copper itself. But I thought it wasn't economic.
Marcos, can you point these products in Brazil: flux and clean lacquer pcb?
I'm having trouble to translate and find the right lacquer.
I think this guy is using 'breu' and 'alcool isopropilico' to make his own flux.
https://www.youtube.com/watch?v=MY4QdROhu6w

Verdade, você é brasileiro. Eu uso pasta de solda da cobix, não é o recomendado mas funciona. Aquele que você postou o link é melhor. O verniz, também o que você postou. E, assim como o Mark, eu cubro toda a placa, até mesmo quando tem bastante plano de terra.

Sobre o procedimento que você postou, o correto é corroer e já aplicar o verniz. O fluxo você pode aplicar na hora de soldar pra facilitar, e depois limpa com álcool isopropílico. Se aplicar o fluxo primeiro e depois o verniz, fica uma lambuzeira na placa e o verniz não adere direito. Caso você opte pela camada de solda, passa o fluxo pela placa toda antes de furar, aplica uma pequena gotinha de solda e vai espalhando ela pela placa. Você vai ver que pouquinha solda vai ser o suficiente pra cobrir um bom tanto do cobre, o fluxo ajuda a espalhar. Depois que cobrir tudo, lava com álcool, de preferência isopropílico, e aí é só furar e soldar. Nesse método, nem precisa de fluxo pra soldar, o próprio estanho já aplicado na placa facilita até demais.

TL,DR for non portuguese speakers : they're also brazilian, I replied in portuguese cause they asked for help on finding flux and lacquer here. Basically, I said I also cover ground planes with solder. If they go this way, then flux goes forst (before drilling the board), then just a bit of solder will be enough to cover the whole board. Then clear the board with isopropyl alcohol. If they go with lacquer, then it's lacquer first, then flux to help the soldering, and then clear the flux with isopropyl alcohol.

[Gargaman]

Valeu, Marcos!

[marcelomd]

Verdade, você é brasileiro. Eu uso pasta de solda da cobix, não é o recomendado mas funciona. Aquele que você postou o link é melhor. O verniz, também o que você postou. E, assim como o Mark, eu cubro toda a placa, até mesmo quando tem bastante plano de terra.

Pasta da Cobix, vulgo cera de ouvido, funciona bem. Nunca entendi por que não é recomendada. Também fui descobrir "fluxo" propriamente dito bem depois, pela internet.

Pra espalhar solda, eu gosto de usar um pedaço de malha de cobre. Funciona como um pincel. Ajuda a "pular" o espaço entre as trilhas. O importante é mão ficar muito tempo num local, pra não descolar as trilha da placa.

Se cobrir a placa toda com solda, pode lavar com água e sabão também. O cobre vai estar protegido.

tl;dr;en: After covering the traces and planes with solder, you can wash the board with soap and water. Copper is already protected after all.

[Kevin Mitchell]

I've used automotive clear coat spray paint without any trouble. I like using "stained glass" or "headlight tint" spray paint as well. Definitely check the ingredients if you can find the sheet. But usually anything that's obviously nonmetallic is fine.

If you're into science experiments you could also make your own liquid tin. Made a thread a couple years back on that.
Homemade Liquid Tin Thread

[Marcos - Munky]

Pasta da Cobix, vulgo cera de ouvido, funciona bem. Nunca entendi por que não é recomendada.

Aquela pasta da cobix que vem no potinho laranjado é corrosiva. Ela é feita pra soldas mais brutas, tipo soldar canos. Até dá pra usar em placas, mas se você não limpar bem, ela oxida e pode resultar em descontinuidade. Uma vez eu fiz uma placa, soldei, e só depois passei a pasta e fiz a camada de estanho. Funcionou por um tempo, depois parou tudo, e tive que refazer a placa. Em outra, furei a placa antes de fazer a camada de estanho. Deixei a placa guardada por umas semanas, quando fui pegar pra montar a pasta que estava nos furos entrou em contato com o cobre e oxidou tudo. O certo mesmo é usar na placa sem furos, fazer a camada de estanho, depois limpar muito bem.