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Topic: Solder mask paste alternatives (SOLVED) (Read 633 times) previous topic - next topic

noob314

Dec 14, 2019, 10:58 am Last Edit: Dec 17, 2019, 03:53 am by noob314
I have made some PCB for SMD micro SD card holder. However, I'm searching for mask paste alternatives, since I don't have any in order to isolate traces metal holder will definitely short. Something easily available, non conductive, with ability not to disintegrate due time.

I have though about nail polisher, however it is very tick and I'm not certain what will happens due time. It also may contain water, thus may also be conductive

Another though was pen used to correct broken traces during process of making PCB. I'm not certain of it's durability.

Then perhaps custom permanent markers.Oil based paint marker may be conductive.

What I'm almost certain it should probably do, may be plastic spray used to protect PCBs from corrosion. I'm out of that as well...

Anyone know what potentially may be used as an alternative?

Paul_KD7HB

Dilute the nail polish with remover until it is just the thickness you want!

Paul

larryd

#2
Dec 14, 2019, 07:28 pm Last Edit: Dec 14, 2019, 07:30 pm by larryd
If you are talking about solder mask, it is design as a solder mask only maybe to prevent oxidation too, not as an electrical insulator.

You could use diluted conformal coating, a mica washer, UV glue or similar.








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MarkT

I'd suggest applying it over the whole area, and carefully abrading it off the pads with a fine abrasive pad or similar - it should remain on the PCB between the traces and pads.

My adivce for small SMT parts is don't try to make your own PCB, get one manufactured complete with solder mask, and stencil, and then you can apply solder paste through the stencil perfectly.  Then there's oven, hotplate
or hot-air rework station routes to flowing the solder paste.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

noob314

#4
Dec 14, 2019, 09:02 pm Last Edit: Dec 14, 2019, 09:05 pm by noob314
It is not that simple. It is not possible to obtain here exactly what I need, else than need to order out of county, additionally pay astronomical postage, pray that customs will not calculate some insane taxes if I order more than one board, etc.

Concrete for this board, I needed to have physical pin to indicate ejection state of the card, which many industrially produced and cheap boards just omit.

Yes I know very well. It is a PITA, however I have to make myself some simpler SMD boards, even I do not really have any proper equipment for that.

larryd

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Paul_KD7HB

It is not that simple. It is not possible to obtain here exactly what I need, else than need to order out of county, additionally pay astronomical postage, pray that customs will not calculate some insane taxes if I order more than one board, etc.

Concrete for this board, I needed to have physical pin to indicate ejection state of the card, which many industrially produced and cheap boards just omit.

Yes I know very well. It is a PITA, however I have to make myself some simpler SMD boards, even I do not really have any proper equipment for that.
Are you the ONLY one in your country doing anything with printed circuit boards with SMT components? IF not, find out how they do it?

What proper equipment do you need? We had an engineer developing a prototype circuit board that was too big for our reflow oven. We did all the work we could and he finished the board by soldering the remaining SMT components by using a big frying pan on his kitchen stove. Said it worked fine.

Surely you have others in your country that can help.

Paul

noob314

Can you find UV glue.
Not sure about  UV glue. I may search for that. Thanks for suggestion.

larryd

#8
Dec 14, 2019, 09:37 pm Last Edit: Dec 14, 2019, 09:38 pm by larryd
I sometimes use 1 or 2 layers of Kapton tape under components.





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noob314

I have actually considered scotch and electrical tape, but the quality is extremely low and they decompose rapidly on air. Electrical tape is better choice, but anyway, I have seen some in electrical installation turned to dust and it was just plain luck it didn't catch fire...

Kapton tape seems to be much more quality and may be used in this case. I can find it here, but price is insane - 20mm X 100FT is around 7 Euro. Here I need just few square cm...

But anyway, thank you very much, it is certainly worth to know.

noob314

#10
Dec 15, 2019, 12:00 am Last Edit: Dec 15, 2019, 12:03 am by noob314
Dilute the nail polish with remover until it is just the thickness you want!
I suppose, if nail polish doesn't contain tap water, this also may work with clean acetone mix...

Thank you as well for suggestion.

WattsThat

Quote
However, I'm searching for mask paste alternatives, since I don't have any in order to isolate traces metal holder will definitely short. Something easily available, non conductive, with ability not to disintegrate due time.
Solder mask is not an insulation layer, it there to prevent solder bridging. If you need to insulate something, use a proper insulator and the kapton tape mentioned is the easiest, fastest and best suggestion. Rolls in just about any width can be had on eBay for next to nothing.

If you cannot use an appropriate tape, some homemade fish paper may work if the thickness is usable for the application. Start with a piece of chipboard, the heavy paper used as a backing for a writing tablet, spray with clear lacquer on both sides to prevent moisture absorption and give it a try.
Vacuum tube guy in a solid state world

wvmarle

Kapton tape seems to be much more quality and may be used in this case. I can find it here, but price is insane - 20mm X 100FT is around 7 Euro. Here I need just few square cm...
Maybe expensive for tape, it's also just 7 Euro, that's not much money.

You really should look for your local makerspace, no way you're the only one in your country that likes to play around with circuit boards.

Shenzhen based Seeed Studio makes boards at just 5 USD for 10 pcs (up to 100x100mm), and a stencil adds some 8 USD to that, plus shipping of course. There are also European producers of boards; as you apparently use Euros there'll be no import duty involved (it's within the EU after all). Good quality boards. With the stencil you can get your solder paste to apply perfectly - it's a bit of trial and error of course the first time, but not that hard, really.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

JohnRob

I would use clear package tape.   I used it on a bathroom fixture 15 years ago.  We remodeled last year and the tape was still clear and well adhered to the surface.  The only issue I see is soldering a component near the tape might cause it to release from the board.

The other possibility someone already suggest would be conformal coating.  I've used some silicone spray conformal coating and it works great.  Be sure to clean the board very well and be sure it is very dry before coating.

Lastly, if the above two don't work for you..... coat the board with GE Silicone II.  You should be able to find it at a hardware store.  It must be the II version.  The older version GE Silicone contains acidic acid and will corrode the board.  The old one smells like vinegar while curing, the Silicone II has very little smell.

John


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DrAzzy

I would also give thought to getting the boards made by one of those cheap chinese board houses - it's surprisingly cheap for surprisingly good PCBs. Unless you urgently need a one-off, it's hard to justify the time it takes to make boards at home.
ATTinyCore for x4/x5/x61/x7/x8/x41/1634/828/x313 megaTinyCore for the megaavr ATtinies - Board Manager:
http://drazzy.com/package_drazzy.com_index.json
ATtiny breakouts, mosfets, awesome prototyping board in my store http://tindie.com/stores/DrAzzy

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