I've used a 400 watt hi-bay lamp (480V ballast) without an envelope
since 1973 - same bulb still going strong. Just keep it in a complete
enclosure with a slot to insert the PCB sandwich.
Norm
guja wrote:
>
> "envelope or not?" poll question.
>
> Leon Heller <leon.heller@...
> <mailto:leon.heller%40bulldoghome.com>> wrote: ----- Original Message
> -----
> From: "Stefan Trethan"
> To:
> Sent: Saturday, October 14, 2006 8:01 PM
> Subject: Re: [Homebrew_PCBs] Mercury lamp for UV exposure
>
> > On Sat, 14 Oct 2006 19:51:57 +0200, Leon Heller
> > wrote:
> >
> >>
> >> It will be mounted in a light-tight box.
> >> Leon
> >
> >
> > But in case it does no good (or little good) what is the point in
> breaking
> > the envelope?
> > Does it really speed up exposure that much?
>
> Everyone else using them does it. It will also help with collimation
> as it
> will be more like a point source. The high-speed exposure units used
> by PCB
> manufacturers use much more powerful mercury arc lamps with special
> optical
> systems consuming 3.5 kW or more and delivering 15 mW/sq cm of UV at the
> PCB!
>
> Leon
>
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>
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>
>
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