Week 3 -- FabISP
FabISP IntroThis week we're learning how to mill circuit boards, solder components, and program the previously mentioned boards. We'll be making a FabISP (in-system programmer) that will be used for the remainder of the course to program any other boards we go on to design.
I milled my first board directly after the training sessoin, so everything was fresh in my head. I used the older machine, so I had to be a bit careful about the sacrificial board being warped. I tested my z-height in several locations to make sure I would always be hitting the board. In the Fab Modules, I set my 2D z-depth to 0.12 and got nice results from the cut. Instead of using the Modella to cut out the board, I decided to try the pressure chopper. I messed up the board on my first cut by going too slowly. The proper way is to line up the board, hold the board firm, and do a nice quick, chop. By going slowly and not holding the board completely tight, I gave the FR1 a chance to splinter and crack - which it did. On my second iteration, I used the Modella to cut out the board.
Soldering all the components onto the board went fairly smoothly. For the components with very small leads (the microprocessor and the usb jack) I made a long solder bridge across all of the leads and then used copper solder wick to pull off the excess. This produced nice results with no bridges and little excess.
The key to soldering these boards, for me, was a good pair of tweezers. Being able to finely manipulate all of the components made the process quite smooth.