I was thinking of plotting right on the PCB. I found the violet LEDs
again (Mouser), and in reading the data sheet, it caution of UV
exposure. The wave length is fairly short ranging from 383nm to 410nm.
I believe one of the PCB sites said there UV tubes were 410nm, so I
think this would work. The LEDS emit a minimum of 2.6mw, typically 6mw
for an SMD up to 18mw min, 100mw typical for a T13/4.
So all I have to figure out now is how many milli-watt seconds
(milli-Joules?) it takes to harden the resist layer. Aperture size
will affect exposure times too. It's possible I'll have to move lenses
around when changing aperture size too (i.e. autofocus). It Might be
easier to locate some negative board and do trial runs at different
feed rates and aperture sizes.
Come to think of it, I have some positive board I could experiment
with. Just need to order some of the LEDs.
BTW, currently I use 4x6 boards. This is closely related to my using
the free version of Eagle. Keeps me thinking, and humble :-)
Thanks!
Regards,
JJ
On Friday, Apr 16, 2004, at 18:32 US/Eastern, ballendo wrote:
> Hello,
>
> Is this to be used for exposing the pcb directly? Or a photofilm?
>
> Bacause there are photofilms which can work with a standard red hene
> wavelength diode. (600-675nm)
>
> You'll need opticcs to focus the beam, and good parallelism between
> axes and table, to keep the spot size consistent.
>
> Be aware that either way, using the cnc/plotter in this xy way is
> SLOOooowwww.... (And you've got to maintain "safe" lighting condition
> during this time.)
>
> My cheap machines can easily accomodate this usage, but I'm looking
> into offering a cheap drum type photoplotter as well.
>
> Along that thought, would an 8x10 or 12x12 film size be adequate? Or
> do you guys need 12x18? Or?
>
> Ballendo
>
>
> --- In Homebrew_PCBs@yahoogroups.com, Cristian <bip@f...> wrote:
>>
>>>
>>>> I'm thinking about making a photo-plotter attachment for my
> router /
>>>> mill.
>>>> Do any of you know of a small UV light source that would be
> suitable?
>>
>>
>> Owing a Bungard CNC, I'm also interested.
>> Visit Maplin UK at www.maplin.co.uk, looking for N76AJ, 'High Power
> UV LED
>> Narrow Directivity' or N75AJ 'Wide.....
>> Cristian
>>
>> [Non-text portions of this message have been removed]
>
>
>
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