Hello Donald,
There is no magic for the formula check http://www.holowiki.com/index.php/Dichromated_Gelatin_Chemistry they have detailed information on it. I'm using PVA instead of gelatin. The problem is you need to be careful using dichromate, it is not environmentally safe disposing requires care. I'm always keeping water used for development in separate container for recycling/disposal center.
I've decided to switch another photoresist which is environmentally safe, they're also selling it on e-bay AQ 3000 Waterborne Photoresist, it is easier and much more sensitive than DCG.
Volkan
--- On Thu, 11/12/09, Donald H Locker <dhlocker@...> wrote:
From: Donald H Locker <dhlocker@...>
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Date: Thursday, November 12, 2009, 6:09 PM
Hello, Volkan.
Looks like you have your fingers in several pots (homebrew pcbs, direct print resist, homemade photo resist). I love it.
Are you willing to tell us more about your formula and processing for the homemade dichromated PVA resist? A friend (30 years ago) did some silkscreen work using (IIRC) Elmer's glue, which is a PVA product. What else is involved? Or a pointer to where you have already told everyone and I wasn't watching. :)
Thanks much,
Donald.
----- Original Message -----
From: "Volkan Sahin" <v_sahin@yahoo. com>
To: "Homebrew PCBs" <Homebrew_PCBs@ yahoogroups. com>
Sent: Thursday, November 12, 2009 5:46:45 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without complicated optics I can get ~3 mil trace width/space. Currently, I'm using Dichromated PVA based homemade photoresist. The problem is without polygon mirror scanner, it is very slow but result is impressive. The exposure time required for 1.5 mil spot is ~20 microseconds.
Volkan
--- On Thu, 11/12/09, lmri2071 <lmri2071@yahoo. com> wrote:
From: lmri2071 <lmri2071@yahoo. com>
Subject: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: Homebrew_PCBs@ yahoogroups. com
Date: Thursday, November 12, 2009, 8:38 AM
I had this idea about seven years ago. But at that time the Laser Diodes
of 405nm were impossible to obtain (USD$4000). Since last year, I have
taken this idea again, because now one can buy those laser diodes around
USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys
experimenting with this, but I have not see the results. Also I read
about a french engineer who made some experiments with UV LEDs coupled
with a fibre optic. I have a Polish paper which expose the use of this
idea to get 50um (2 mils) clear cut beatiful traces, but they use very
expensive optics ( telecentric lenses, glavos and others things which
are too costly for the DIYer ).
Now I struggling with optics. When I get some control of the LASER beam
waist, I gonna put my laser module in a CNC engraver.
There are anyone working on that in this group?
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