Positive Photo-Sensitized Board

[smallbearelec]

I got in 3" x 5" pieces of this on the last boat and have posted for sale, my SKU 0411J. If you use it, I hope you will order from the Cave, because I have it for half the prices I have seen elsewhere. It's good material--I have tried it--the other sources are just charging more. A few notes:

The last time I worked with the positive process, some years ago, I used adhesive address/shipping label stock to make the transparencies. That stuff is translucent; I got the process to work, but the lack of full contrast between the pattern and the label stock made exposure time more critical than I thought it should be. I knew that I really needed either a contact-type spray adhesive to use with traspanency film, or, preferably, a truly clear, inkjet-compatible transparency stock with adhesive on one side. I went fishing today and found exactly that at an art-supply store. This company: http://www.grafixarts.com/ offers it, and I will ask if they'll sell to me wholesale. I believe that Avery # 53212 Window Decal Stock is a similar product, but I could not find it in the local Staples or Office Depot--might be one of those items that must be mail-ordered.

I printed to the transparency stock on a standard HP 4215 all-in-one and applied the resulting positive to the board. Exposure was 7 minutes @ 2 inches from a 15-watt fluorescent lamp. This turns out to be a little too long, and I will be doing some more experiments. Developer was made from one level teaspoon of Sodium Hydroxide to one pint of water. Etching was with Ferric Chloride. I have not tried Sodium Carbonate for the developer yet, nor Persulfate for the etchant.

Once I have all my ducks in a row, I'll do another tutorial and a kit.

Regards
SD

[toneman]

i'm interested in that U mixed your own developer!!

Keep us posted on the testing!

thanx for all the work!

T

[composition4]

I promise that once you go to photo-resist, you will never want to go back to toner transfer.  Initial set up is slightly harder (only slightly).  As long as you have transparencies, a fluoro light (even the UV fluoro blacklights are fine despite what people say) and a piece of glass, you're set. Expose board/transparency/glass sandwich to UV light for approx 10 mins (just do a staggered 2.5min x 7 test to determine the best time for your setup, will sacrifice a board but it's only 1 in your life!). 

I use sodium hydroxide to develop, 10g pellets to 1 litre room-temp water.  Then just etch with your favourite etchant.  The results are absolutely perfect, detail is unbelievable (I can do 5 mil traces and 5 mil gaps no problems, not that I want to).  And the whole process is very forgiving

Sorry to hijack but I'm just a big fan of photo-method and glad to see Steve is pushing for it

Jonathan

[smallbearelec]

Expose board/transparency/glass sandwich to UV light

Thanks for the encouragement! I have found that the adhesive transparency film makes the "sandwich" unnecessary. I hope to be able to offer that at a price competitive with toner transfer film. The board stock is much more expensive, and it has a shelf life. But I have brought the cost down initially and will ultimately order some more sizes if the small ones move.

SD

[Pigyboy]

^^^
Hi Smallbear,
If you get a good starter kit I am in too(if shipping to Spain is not too expensive ) I started to do some research into this method and am ready to give it a go!
Cheers,
Chris