Homebrew PCBs

Adam,

I do have a 20mm grid spacing, and I'm so far satisfied. Even though it 
never formed a problem of any kind, one can SEE the grid on the 
resulting exposed laminate. It's seen like kind of darker and lighter 
circular shaped areas on the exposed resist. Again, developping the 
result always worked excellent with no irritations in the result whatsoever.

At the very surprisingly low prices of these LEDs, I would consider 
using an even more narrow grid. My box (kingbright leds, with what I 
understand only 160mcd typical) result in a one minute exposure time. 
So, with the 7000mcd ones, you might be not fast enough in flashing them 
on and off for the exposure :-) ....

Let us know what the outcome of this will be. Me thinks that the first 
seller in your list is the more interesting one due to the fact that 
those LEDs seem to have a more narrow angle and compared to what I have 
(160 vs 3000) those LEDs still seem to be superior. On the other hand I 
heard from a guy who bought UV leds over e-bay that they were not 
useable at all. This sounds odd to me though if the specs given on the 
sellers pages reflect the truth. Again, I will be interested to hear 
about your experience, and with $11 you risk not that much. I probably 
would try to expose a sqare inch of resist using one LED "on the fly" 
(make sure you don't look into the UV but who am I to tell you this) 
before I would spend the time to build a complete exposure unit to make 
sure they work.

Markus

Adam Seychell schrieb:
>
> Hi,
>
> I'm wondering if anyone knows where is a good place to buy >= 100 UV
> LED's for home made PCB exposure box ? There are two sellers on eBay
> that I have found: (all prices below include delivery)
>
> http://stores.ebay.com/Winsome-House-Store 
> <http://stores.ebay.com/Winsome-House-Store>
> They are advertising 100 x 3000mcd(typ.) 20 degree UV LEDs for US$11.
> This sounds almost too cheap.
>
> http://stores.ebay.com/Light-of-Victory-Led-Store-lvehk 
> <http://stores.ebay.com/Light-of-Victory-Led-Store-lvehk>
> They have 100 x UV LEDs 20 degree 7000mcd(typ.) for US$32.
> or 100 x UV LEDs 20 degree 3000mcd(typ.) for US$15.
>
> It would seem I could use half as many of I buy the 7000mcd compared to
> 3000mcd. I'm guessing a 20mm grid spacing would be a good layout for the
> LEDs.
>
> regards,
>
> Adam
>
>