Late last week the parts arrived from my Carambola i2c IO board and I was busy over the weekend making and assembling the PCB. Here are the results!
I used KiCad to create the artwork and my ink-jet printer to print it out onto OHP film. Got better results with my ink-jet than my laser printer, the ink is a lot darker than toner. As this is a double sided PCB I spent a good while getting the alignment correct, which was tricky!
For a UV source, I got an external 24W CLF bulkhead light which at a five minute exposure time worked the business. The back of the PCB worked out fine apart from the dodgy cheep FR4 board I got from Radionics. The photo resist film on the copper was really crappy as you can see in the photo below (look in the centre of the PCB, the artwork was black but you can see the Cu has been etched in patches).
The top side was a little better apart from the PCB area at the top right of the board where there was a big blotch of resist.. Also the alignment of the top and bottom artwork was a little out on the right despite my best efforts.
Here is a close up of the track detail where they are at their closest, nice crisp tracks.
The switcher PSU with the 3.3V regulator:
And finally the assembled PCB..
The good news: it works!
Well I haven’t tried the Ethernet UTP connection yet, but the WiFi, PSU, input stage and relays work fine.