I already found what I was looking for; that photo-resistant lacquer is ideal: easy, cheap, fast, and you make the solder mask as well as the track etching in the same application.

Can you provide a link to that particular product? If it is used also for the solder mask, how do you remove it from the pads? Or, are you simply soldering through it?

John

 

You only apply it once, but you need to radiate it twice with 2 transparencies; the first for the etching, and the second for removing the product from the pads. Then the product itself remains as the solder mask.

There are various brands, though "Positiv 20" from Kontakt Chemie was the one recommended.

 

Thanks for the link. That product is a typical DNQ-sensitived Novolak resin. The DNQ allows near UV and short-wavelength visible light to work (e.g. 420 nm light will work).

Is there an Instructable or YouTube link for the second exposure and development? One thing you may need to consider is the lighting present while you develop and etch the board. Fluorescent lights are quite common today and they produce considerable light in the wavelength range that will affect the photoresist. Most etchants will be opaque to UV light, but the board will not be in the etchant 100% of the time.

If you get removal of too much of the original resist covering the traces when you do the second exposure and development for the solder mask, you might want to consider doing the first development and etching in a dimly lit room with incandescent lamps.

John

 

You can find an example of the whole process in this video:

 

I need a 2 layers PCB for a new design prototype, and can't find anyone that would just print me one (75 x 100 mm) for a good price -the cheap ones will only print a minimum of 5, the ones that do are too expensive, or the P&P is too high

You can check prototype PCB prices, including shipping, from 21 different PCB manufacturers by going to **********.com and entering your board's specs and the quantity you want.

If all you want is one board, tell it that, even if you know that most places sell a minimum of 3 or 5 or 10. ********** will look for the cheapest way to obtain one board, and if that manufacturer happens to give you more than one, ********** will let you know.

 

Thanks, I'll have a look.

If anyone is interested: Last week I found this other place: http://smart-prototyping.com

They also send you 10 PCBs with the same characteristics as discussed above, but for half the price; only $9.99 plus P&P.