Over the Labor Day weekend, I could not bear to leave my computer at home.  While my wife read in the evenings, I worked out the design for my newest circuit board.  This board will incorporate an Atmega 2560, TQFP 100.  That's 100 pins at 1/2 mm spacing.  Good stuff. Now, I've done a TQFP 144 board...but it was just a breakout board.  This board actually has to do something.  That's a bit more challenging.  Getting the whole shebang to work on one layer may have been possible, but not very practical.  I have big plans for this board! (Insert maniacal laughter)  These big plans necessitated a two layer board.  My first, as it turns out. Although I have never created a two layer board, I have rehearsed the process in my mind many, many times.  The big problem is getting the registration right between the two sides.  My technique was pretty darn good.  I would glue a paper printout of the circuit to the outside of board and drill holes through the board before removing the plastic sheeting and exposing it....

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