The quartz halogen car headlamp bulb successfully exposed the PCB.
I ran the bulb at 13.8V with just the 65W filament connected at a distance of about 4" from the PCB for three and a half minutes.
The artwork was produced with SprintLayout v5 and inkjet printed with a canon MP600 on to regular A4 copy paper with printer set
to highest quality. I took the inkjet print to a copy centre who photocopied it at darkest setting on to what looked like
tracing paper but was probably a plastic material they use to print technical drawings.
I will probably get a number lower wattage quartz halogen car bulbs and make up a light exposure box. Quartz halogen car bulbs
are easily obtainable and not too expensive and no ballast is needed.
I did the test on an old piece of SRBP. I'll repeat it with some new RS glass epoxy FR-4.
John G3UGY
--------------------------------------------------
From: "Robin Whittle" <
rw@...>
Sent: Wednesday, August 01, 2012 3:01 PM
To: <
Homebrew_PCBs@yahoogroups.com>
Cc: "v321uk" <
v321uk@...>
Subject: 12 volt QI headlight lamp as UV source for exposing photoresist?
> Hi John,
>
> I am responding to your message in: "Re: PCB light box - hf ballast /
> tube wattage - 400W floodlight instead?", in which you wrote:
>
>> Do you think a car quartz halogen headlamp would have sufficient UV
>> output ? I have a new 12V dual filament 50W + 65W which I could
>> parallel to give 115W.
>
>> My PC is only 8cm x 3cm.
>
> I guess a quartz iodide (AKA quartz halogen) headlight lamp would work
> OK with a distance suitable for small boards and with a few minutes for
> exposure. However it would depend greatly on the voltage you ran it
> from. The UV output of an incandescent filament goes up dramatically
> with its temperature, so if you ran it from 11 volts and got little
> action, and from 13 volts and got a much greater UV output, I wouldn't
> be surprised.
>
> With these currents and voltages I think it would be good to use thick
> wires and measure the voltage at the lamp terminals. I suggest running
> it at 13.8 volts - which is a typical maximum voltage in a car.
>
> Some kind of reflector, such as made from a nicely bent fragment of
> aluminium pie dish would help.
>
> As with the 400W quartz halogen floodlamp, I think heating of the board
> might be a problem. A fan blowing on the board should fix this.
>
>
>> Alternatively, I have a new 12W T5 circular (11cm 41/2") Fly Zapper
>> tube.
>>
>> The sensitised PCB needs energy around 360nm.
>
> I don't know what their output wavelengths are, but as far as I know
> they are not in the 350 to 380nm near UV range. Do you have a tube
> number? Googling it should turn up a spec sheet.
>
>
> - Robin http://www.firstpr.com.au/pcb-diy/
>