Duke University Motorsports is a student group that designs and builds open wheel, single seat race cars to compete in the Formula SAE competition sponsored by the Society of Automotive Engineers. The team consists of Duke students from both Pratt and Trinity, in all classes. The purpose of the team is to provide students with a way to gain practical design and manufacturing experience in a fun and challenging setting.

Friday, March 16, 2012

Aero controller electronics

I got the PCBs for the aero controller in the other day (also from Laen's PCB order), and soldered them up.  So far, so good.  The accelerometer was the part I was most worried about since it is a LFCSP package with no visible leads (and thus no real way to inspect and rework), but I tested the board and all three axes of the accelerometer work great.  The DAC works too, so the last step is just interfacing the Arduino and Jrk motor controller.
Aero controller board, all soldered up

Once again, the process of assembly is standard SMT reflow.
Starting with the boards and a pile of parts, apply solder paste on all the pads.  Next, place components on the board.  I usually inspect under the microscope to check alignment, and here it's crucial to have proper alignment marks on the silkscreen for parts with no visible leads (i.e. the ADXL335 accelerometer, which is a LFCSP package).  Stick it in the oven, and let it reflow.  This board was easy because all the SMT components are on one side (if it's possible, it's good practice to keep all components on one side to keep assembly easy).
Board in the toaster oven
After all the SMT parts are in, you can solder in the through-hole parts, which will be done by hand since you probably don't have a wave soldering machine.

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