Sunday, November 1, 2015

Two More NMEA WiFi Bridge Boards

If I could only learn to take good photos
I etched two more of the NMEA WiFi Bridge boards. After only a week of messing with the layout in Eagle, I finally decided I had a valid rev x.3. It seems I left a Vcc trace off the x.2 board.

Printing the inkjet transparency went well this time, marking solid and black in eagle print, although the color came out greenish. I exposed the pre-sensitized board 1 minute 15 seconds in the 1:30 afternoon equatorial sun then immediately developed them in caustic soda from last year for about 3 minutes. Then etched in new peroxide and muriatic acid for about the same 3 minutes. They looked really nice for a change.

I then exposed them to the sun again for 2 minutes and used the caustic to get the rest of the green photo-resist off the traces so I could solder.

I tried to coat all the copper with solder, but the very fine letters just pealed off the board. I had levf a +, -,  G and Rx in copper near those pins.

It took less than 3 hours to print, etch and populate the 2 boards. Of course that doesn't count the week fussing with the layout!

I decided to leave the voltage regulator off these because I have a number of $2 Chinese buck converters that have good regulation in the 3.3v range to pair them with.