Homebrew PCBs

I use four cheap fluorescent lamps (9W each, if I do not miss-remember)
attached together with a diffuser cover and the time is between eight and
nine minutes for a simple-sided pcb or seven minutes each side for a
duble-sided pcb. It is absolutely. As Robin appointed, fluorescent lamps
need a pre-heat time to work best.


2013/1/7 Jeff Heiss <jeff.heiss@...>

> **
>
>
> What are thoughts on exposure time vs. resolution? Pretend a 100w bulb
> gives a 10 minute exposure and a 200w bulb gives a 5 minute exposure. Is
> either better, worse, the same?
>
> Jeff
>
>
> -----Original Message-----
> From: Boman33 boman33@...>
> Sent: Monday, January 07, 2013 2:41 AM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: RE: [Homebrew_PCBs] UV nail lamps - sharpness of shadow,
> phototool-PCB contact closeness, 500W floodlamp
>
> Use thicker glass and let the PCB deform to lay flat against it. The force
> of the vacuum (air-pressure) is very large over the big area of the PCB.
>
> Bertho
>
> From: Jeff Heiss Sent: Monday, January 07, 2013 01:46
>
> I experimented with a ziplock bag and a vacuum pump. The transparency is
> held to the board very very well. Much better than glass can ever do.
> However, I found a drawback and that is the plastic forms imperfections and
> scratches from fingernails, stretching and pulling to get wrinkles out
> during vacuum, and around the transparency and copper clad edges.
>
> I question, as I have not tested, if these imperfections can cause
> diffusion
> of the light as it passes through and decrease results especially if the
> imperfections are over a thin trace or spacing between traces. I tried
> blanket storage bags, same problem. My conclusion is that very thin glass
> like microscope cover slide glass is the ideal material because it is thin
> enough to deform over the copper clad. I searched for glass as thin as
> cover slide glass but I could not find a place who sells it. Maybe
> something better than ziplock bag plastic can be used too that I am not
> aware of.
>
> Jeff
>
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>
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>  
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