Making PCBS

[Alec Hayward]

Hi everyone, I was thinking of making my own PCB's but am confused as to what chemicals are needed.

I want to use some dry film photoresist, which i will apply to copper boards.

Can I use Sodium Hydroxide to develop the photresist? Then just use Ferric Chloride to etch the PCB?

Thanks,
Alec

 

[Harald Kapp]

That's the usual way.

Try Gogle for more tips (etch times, transfer methods for the traces, etch jigs etc.)

 

[Alec Hayward]

I have been researching for a while, but the different methods people use confuse me a little.

Some people use different other solutions to develop. This person in the link below recommends using
sodium metasilicate pentahydrate. Saying it's much better than sodium hydroxide, because it makes it difficult to over develop.


http://www.electricstuff.co.uk/pcbs.html

 

[(*steve*)]

I would start by using whatever is recommended by the manufacturer of the film.

If you decide to experiment later, you will have something to compare it to.

 

[Jouellet]

Personnally, I use Ammonium Persulfate:
http://www.mgchemicals.com/products...-repair/prototyping/ammonium-persulphate-410/

I prefer that over Ferric chloride which is messy like hell ! I also tried Sodium persulfate, but found Ammonium persulfate more efficient.

with 1 Kg of ammonium persulfate I make about 20-25 4x6 board , Warming it up, makes the process faster.

To develop my board, i use http://www.mgchemicals.com/products...it-repair/prototyping/positive-developer-418/

the recipe is roughly 10:1 (10 being the water part) You will be able to develop almost 200 boards with a bottle of developper

I print (LASER) my artwork on regular transparencies (Staples): I use 2 copies of the same artwork to get a real good opacity,

I have made 150+ boards using that method...

 

[Alec Hayward]

I'm not too worried about the mess, but its good to know a different etching solution incase I choose differently.

I use 2 copies of the same artwork to get a real good opacity

I really like the idea, perhaps printing twice on the same transparency would work?


So do I need a positive developer or negative developer? Is the different in the photo-resist dry film or the solution?

 

[Jouellet]

Alec: depending of the size of the board to make, you may be able to print twice on the same page.. I do print them on 2 pages and put them one on top of the other (and scotch them)

As for being worried or not and the messy etchant, just do it once on the kitchen counter top, when your wife is around, and you WILL worry: survival instinct takes over pretty quickly !

I use positive method. I buy my board "positive-ready". I normally buy them from Ebay or Aliexpress. do a search for "Positive Acting Presensitized PCB". Ebay is a bit more expensive than Aliexpress. I buy them 10 at a time, and pay approx. 26-30$ w/shipping, for 10 x 4"x6" boards.

I have tried a spay called "Positiv 20" that claim to allow you to sensitize a regular PCB board. First this spray is a bit expensive, but it is extremely hard to find in North America (got mine from Europe). the results are so-so and it is hard to get a good coat of that stuff evenly applied. Not worth the effort !

Dry-film is also an option that I tried, but they are mostly for negative method, and at about 3$ for a positive board, once again, not worth the effort for the small saving that you get .....

hope that helps to clarify....

 

[Colin Mitchell]

It's all cheaper to get the boards made in China with an overlay, solder mask and tinned lands.
I stopped making PCB's 40 years ago as they look atrocious.

 

[(*steve*)]

I stopped making PCB's 40 years ago as they look atrocious.

Your constraints and limitations are not going to be the same as everyone else's Colin.

 

[Jouellet]

If I need quantity, I use China as well

When prototyping/designing I make them myself: When the schematic is done, I have a board made/drilled in less than 2 hours... Your chinese dude can't beat that... Period !

I don't know how you used to make your boards, but mine are nothing to be ashamed of !