Sunlight.
Short wavelength UV doesn't pass through glass very well. The good UV
bulbs are made of quartz, hence they're kinda pricey.
I've done boards in sunlight with some success. The trouble is, the
amount of UV you get from the sun varies widely from day to day and I
think humidity eats it up.
Russell Shaw wrote:
> David McNab wrote:
>
>> Hi,
>>
>> I'm looking to try out photo etching and am considering the options.
>>
>> Can someone please recommend a UV lighting source which:
>> - is cheap
>> - has consistent UV output
>> - is readily available, or easily made up from items from general
>> hardware stores
>> - gives good results with low exposure time (preferably 5-10 mins,
>> I'm not keen on 30 minutes)
>>
>
> Bunnings sell a helical dark blue (Woods glass) fluro tube that screws
> into a normal light socket. Rig up six of them. (I haven't tried these).
>
>
>> Also, is it hard to get good results using spray-on resist?
>>
>
> Yes. With 4 "small" flouro tubes about 50-100mm from the pcb, PRP takes
> about 3-5mins IIRC.
>
> > Should I
>
>> just cop the extra cost of pre-coated PCBs?
>>
>
> To make PRP work well means cleaning the PCB well before coating it.
>
> Precoated PCB is less hassle to prepare, but more expen$ive from retail
> shops. I get mine much cheaper from the pcb house i use.
>
> The normal precoated pcb from the board house is 100x more sensitive
> to uv light, so exposure time in normal uv light boxes may be ridiculously
> short.
>
>