Excellent news, I thought that Bichromate photoresist needs a high energy density. I gonna try with dry films for etch resist and solder mask with a LASER diode of 65 mW to 85 mW. They are sensitive between 350nm to 420nm wavelength and have an energy density between 25 to 60 mJ/cm2 (Think & Tinker Ltd.). At the begining I though to modify an old LASER printer (replace the IR diode) and try. Is good to know that you get 3 mils with your own implementation.
Lucho
--- In Homebrew_PCBs@yahoogroups.com, Volkan Sahin <v_sahin@...> wrote:
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> 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
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> --- On Thu, 11/12/09, lmri2071 <lmri2071@...> wrote:
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> From: lmri2071 <lmri2071@...>
> Subject: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
> To: Homebrew_PCBs@yahoogroups.com
> Date: Thursday, November 12, 2009, 8:38 AM
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> I had this idea about seven years ago. But at that time the Laser Diodes
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> of 405nm were impossible to obtain (USD$4000). Since last year, I have
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> taken this idea again, because now one can buy those laser diodes around
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> USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys
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> experimenting with this, but I have not see the results. Also I read
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> with a fibre optic. I have a Polish paper which expose the use of this
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> idea to get 50um (2 mils) clear cut beatiful traces, but they use very
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> expensive optics ( telecentric lenses, glavos and others things which
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> Now I struggling with optics. When I get some control of the LASER beam
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> waist, I gonna put my laser module in a CNC engraver.
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> There are anyone working on that in this group?
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