Homebrew PCBs

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.