Homebrew PCBs

24.05.2003 06:13:44, "Jonathan W" <n0ym@...> wrote:

>--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon_heller@h...>
>wrote:
>> 
>> 
>> 
>> >From: Neil <cobra_neil@a...>
>> >Reply-To: Homebrew_PCBs@yahoogroups.com
>> >To: pcblist <Homebrew_PCBs@yahoogroups.com>
>> >Subject: [Homebrew_PCBs] I have a dream...
>> >Date: Fri, 23 May 2003 03:36:00 -0500
>> >
>> 
>> Even better would be something like a home-made laser plotter with a UV 
>> laser plotting directly onto the resist-coated PCB. Send it the
>Gerber file 
>> and take out the exposed PCB a few minutes later, into the developer
>and 
>> etchant, and one has an etched PCB. That's what I dream of!
>> 
>> Leon
>
>It would appear that several people are thinking along the same lines.
> The LCD screen idea occurred to me (either with changing the
>backlighting to a UV source or using one of the older overhead
>projector LCD screens), as did using a TI Digital Mirror Device
>(something that looks like it might already be in the works at some
>companies for some photoprocessing equipment and PCB manufacturing). 
>Given the resolution needed, obviously you'd probably want an image
>that could be stepped across the board -- no single DMD has sufficient
>pixels to cover a good-sized board with thousandths-of-an-inch resolution.
>
>As for the laser idea, well, that's something I've been thinking about
>a lot lately, too.  I recently dismantled a malfunctioning Laserjet
>III and obtained the laser diode scanning assembly; replacing the
>laser diode should be easy enough once Nichia and others start
>mass-producing them, although I'll need to ask HP whether the optics
>will pass UV light and focus it sufficiently.  
>
>The challenges would be installing the scanner on a precision-motion
>shuttle with some sort of stepper motor for moving the laser down the
>PCB as each line is "drawn" (maybe using the original LJIII stepper),
>correctly spacing the optical assembly for accurate to-scale imaging
>for several thicknesses of copper-clad board, and controlling the
>whole deal based upon image or gerber files.  It would also be nice to
>know whether the laser scanning assembly is actually capable of
>1/600th of an inch (or better) spot size focusing.
>
>It would be necessary to slow down the laser scanning from that used
>in the original LJ III; with a 2 mW laser and reasonably sensitive
>(e.g. 50 mJoule/cm^2) photoresist, covering an entire board could take
>more than an hour (25 seconds per square centimeter, give-or-take). 
>Of course, if one used higher-sensitivity resist, one could go faster.
> It would be nice to be able to adjust speed to compensate.
>
>I guess if I make it work, I'll let you guys know :)
>
>Jonathan
>

the hp3d has 300x300 dpi.
i don't think this would work.
but it would really be nice to simply print to a normal lj.

(in a laser printer, how is the laser deflected in the horizontal?)

you would also have to adopt all the paper sensors for x/y exposing.

regards
stefan

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