Author Topic: Prevent board from oxidizing  (Read 620 times)

marcelomd

Re: Prevent board from oxidizing
« Reply #20 on: June 09, 2021, 02:28:48 PM »
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.

Hmmm I usually etch, drill, tin and wash right away. Then I'll solder and wash again with isopropil alcohol and a toothbrush. I hate the residue that paste leaves. It gets gooey and nasty.

Gargaman

Re: Prevent board from oxidizing
« Reply #21 on: June 09, 2021, 03:25:45 PM »
Quote

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
Yes

Blz!
Encomendei uma pasta e fluxo (no clean) da Implastec, além do verniz.
Vou primeiro tentar fazer o esquema de espalhar o fluxo e cobrir com solda.
Uma coisa que já mudei aqui e deu certo foi furar depois de corroer; com o meio do pad corroído facilita centralizar a broca.
Testei também goma-laca como verniz; dá até pra soldar por cima, mas acredito que sirva só pra guardar a placa por um tempo caso não for soldar na hora e quando for soldar remover tudo com álcool.
PS.: caso use o verniz apropriado pra finalizar, não aplica no lado dos componentes, certo?

Just saying I tested etching before drilling (done good), experiment with shellac, etc. while waiting for a proper flux and lacquer.



"Such a shame, nothing but existing."
Jimi Hendrix

amptramp

Re: Prevent board from oxidizing
« Reply #22 on: June 10, 2021, 06:56:56 AM »
The companies I used to deal with used solder plating which is a room-temperature process that does not stress the connection between the copper and the board.  We found that high tin content in the plating made for very pretty almost mirror-finish boards but the duller boards with more lead in the mix actually soldered better.

At one time, there were 45 PCB shops in the Toronto area.  We used to use Graphico Precision a lot but we tried out a few more like Metaplast just to have a second source.  I am not sure any PCB houses remain.

StephenGiles

Re: Prevent board from oxidizing
« Reply #23 on: June 11, 2021, 02:29:59 AM »
I built most of the EH Rack Guitar Synth on vero (como siempre!!) in 1980 - no treatment and no oxidisation yet - after 41 years!!!
"I want my meat burned, like St Joan. Bring me pickles and vicious mustards to pierce the tongue like Cardigan's Lancers.".

Rob Strand

Re: Prevent board from oxidizing
« Reply #24 on: June 11, 2021, 03:38:56 AM »
Quote
I built most of the EH Rack Guitar Synth on vero (como siempre!!) in 1980 - no treatment and no oxidisation yet - after 41 years!!!
All the Vero I've ever had, and also those pre-made patternated boards for IC's, have been pre-coated with a fine clear lacquer by the manufacturer    That's why they never oxidize on the shelf in the stores.

I've got an old piece of vero from 1994 which is in my junk parts and it gets handled a bit more than normal because I'm digging through the pile.  It's just starting to develop small areas of oxidation partly because some lacquer has rubbed off against other parts and partly because the lacquer is starting to decompose and flake.   The other half of the same piece has been stored away in a box for years without anyone touching it.  I haven't looked at it for a while.  It would be interesting to see what state it is in.

EDIT:
I'm talking about the ones that look like copper here.   Some were tinned and I'm sure a lot of those didn't have lacquer.
« Last Edit: June 12, 2021, 12:18:12 PM by Rob Strand »
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