Homebrew PCBs

That makes sense. ... Thanks for the great explanation.  Basically the
quality (intensity and spectrum) of the UV is better.
><> ... Jack

On Thu, Jan 28, 2010 at 6:31 PM, jcarlosmor <jcarlosmor@...> wrote:

>
> > I have a feeling its because professional production have big 300mm x
> > 400mm size panels and the number of LEDs in one unit just makes it too
> > large. It would have like 400 LEDs per side. Where as at present they
> > just stick a few tubes in which can be replaced easily.
> >
> > Trev
>
> No, sorry but that is not the reason. A typical exposure UV unit for
> industrial use can cost USD$10,000.00 and that is just the beginning prices.
> Although thousands of LEDs per side would be required, the number (and
> price) of them it is not significant in the industrial shops. The other main
> reason to avoid LEDs that I forgot to explain in another post is that the UV
> emission is very poor compared to fluorescent and mercury lamps. You could
> fix that getting closer the LEDs to the PCB board but that is not desirable
> in any way. To obtain real small traces and details the solution is to put
> the UV source and the PCB so far that is practical, so you would need very
> high ouput in the light source. Some professional UV units have the PCB and
> UV source separated more than 90 centimeters. However they use very high
> mercury-lamps and the exposure only needs a few seconds. Typical
> semi-professional UV exposure units (like MegaUK and so) made from
> fluorescent tubes also have narrow distances between the PCB and UV tubes,
> but that is a reason of compromise, trying to balance cost and performance.
>
>


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