Assignment 7: Design and fabricate PCB board

For this assignment, I attempted to fabricate the base board to do the biometric sensing for my final project. The analog circuitry is based on the design for assignment 5. I originally tried playing with the modela to fab the board, but it is difficult in general to get the machine to fab nice usable boards (issues include etching depth problems due to the curving of the boards, the rather crude design rules/trace spacings because of the limits in resolution, etc). Here's a picture of the original layout using protel:

Using the modela seems like a very nice idea to be able to rapidly portable prototype boards in theory, such as in rural areas where pcb fabs are not readily available or you need to prototype a board immediately and cannot wait the few days turnaround time. However, for my purposes, I needed to fit the circuitry within the 2" x 4" footprint of the SAK/hoarder baseboard with some SOIC packages, which is not possible when using the modela. I ended up using a blank biometric board with the circuitry I needed that Vadim had previously fabbed.

Here's a couple pictures of the board, before it was populated and after I stuff it (the small delicate surface mounted soldering was really a pain to do, even with a magnifying glass and special surface mount soldering tips):

The sensor board was designed to plug directly into the daughterboard connector on the SAK/hoarder baseboard. Here we see how the two boards connect together:

 

 


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