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Electronics => Electronics => Topic started by: blackbeard on December 18, 2009, 07:04:07 PM

Title: not sure if i have all the right chemicals for photo etching
Post by: blackbeard on December 18, 2009, 07:04:07 PM
so i've researched photo etching using a developing agent and a UV lamp before submersing in enchant. i think i have all the chemicals i need but the people at the store i bought them at didn't sound very knowledgeable so i'm not sure that i have the right ones. i have ferric chloride for etching the pcb and a chemical called "negative developer" which they said is what i need for untreated copper clad. according to them the positive developer was for pcbs that come pretreated with another chemical. does anyone know if there are any chemicals i need to etch basic copper clad? also will a few compact fluorescent bulbs produce enough  UV light for this process or should i use uv leds?
Title: Re: not sure if i have all the right chemicals for photo etching
Post by: Soeren on December 19, 2009, 05:39:44 AM
Hi,

You need negative developer if you use negative resist (some presensitized board are with negative resist, but they're very rare (=close to impossible to find) on the hobby market.

You cannot make a photo transfer without the PCB having a photo-resist film (being "sensitized") and you need the developer to match the resist.

If you buy presensitized boards, simple drain cleaner can be used for developing it (after the transfer by UV).

Does any of that answer your question?
Title: Re: not sure if i have all the right chemicals for photo etching
Post by: blackbeard on December 19, 2009, 09:00:48 AM
yes it does most certainly does! it's also thought me that my local electronics store is not the right place to ask for advice :P. i think i'm going to try the toner transfer method since it seems to require the least amount of  time and chemicals. also it looks like the cheapest since the pre-treated boards are about tripple the cost of basic copper clad. do you know of any sites where you can buy all the chemicals needed to do the photo etching method on regular copper clad boards?
Title: Re: not sure if i have all the right chemicals for photo etching
Post by: SmAsH on December 19, 2009, 03:58:47 PM
Is that including a printer/paper?
Title: Re: not sure if i have all the right chemicals for photo etching
Post by: blackbeard on December 19, 2009, 04:07:23 PM
Is that including a printer/paper?

nope. people throw out laser printers all the time around here (likely for windows compatibility) and most even have some toner left. as for paper i can get inkjet photo paper or translucent printable plastic from the local staples but if you know of specialized paper for the photo process i'd give that a try. what i really need to know is a place for economical photo etching supplies such as chemicals to pre treat copper clad boards or economical pre treated boards.
Title: Re: not sure if i have all the right chemicals for photo etching
Post by: Soeren on December 20, 2009, 04:51:11 AM
Hi,

For photo transfer to presensitized board, I use drafting paper printed on a LASER.
In case you don't know what drafting paper is, or in case it might have a different meaning where you live... It is a matte translucent "paper" most often made of some kind of plastic. If you lay it on top of another drawing, you can copy it by tracing (perhaps could be called tracing paper in some places?).
It outperforms clear acetate sheets, as the toner sticks better on the matte surface and the diffusion of the light helps too.

A fairly rigid (thick) sheet is what I have had the best result with - the equivalent of at least 90g/sqr.meter (so somewhat heavier stock than regular copying paper (which is usually 80g/sqr.m).

Make sure to get a type that works with a LASER, so it doesn't curl up inside the very hot fuser.


This stuff works well as a diffuser for LEDs as well.