Russell Shaw wrote:
> Mike Young wrote:
>
>> ----- Original Message ----- From: "derekhawkins"
>> <derekhawkins@...>
>> To: <Homebrew_PCBs@yahoogroups.com>
>> Sent: Wednesday, November 16, 2005 4:37 PM
>> Subject: [Homebrew_PCBs] Re: A $500.00 "UV" non-trivial exposure box.....
>>
...
> From then-on, whenever you want to make a double-sided pcb, just put the
> blank into the sandwich, then put that into the lightbox and expose for
> 90secs. Turn over and do the other side for 90secs. Pull out pcb and remove
> cellophane plastic layer from pcb. Put into flat container that has 10g/L
> of swimming-pool NaCO3 (sodium carbonate pre-heated in microwave for 30secs
> to 25-30degC). Brush developer for 1-2mins until well done, repeating for
> both sides.
Now etch for 7-8mins in ferric-chloride bubble etcher at room-temp, or put
into flat tray and brush over with paint brush. After bubble etching, it's
always a good idea to brush a bit to etch any stubborn parts. Precoated
boards get more stubborn areas of unetched copper you can get etched by
this brushing step, and the problem gets worse with age. I've still got
perfect results from 5-year old board i kept in a fridge, after some
brushing. The bubble etcher was $50 from a shop and is slightly larger
area than an A4 page (it stands vertical).
> Rinse, then put into flat tray with 10g/L NaOH (sodium
> hydroxide garage floor cleaner), and heat in microwave for 1min to 50-60degC. The
> resist just wrinkles and falls off. Rinse then dry. No scrubbing or cleaning is
> needed anywhere.