Here is the stack of ten boards fresh from PCB Train:


The white card behind them is a standard business card, which gives you some idea of how tiny these things are. These were then promptly cut with a PCB guillotine to separate the eyes from the expansion board:

Two eyes will stand vertically at the front of each expansion board, as the following mock up demonstrates:

The first problem experienced during construction is that the reverse of the inductor (shown in photo below) has a lot of exposed contact area. This is fine, except there is some ground plane and some signal lines routed directly under it on the board. To get around this I experimented with electrical tape stuck to insulate these tracks from the inductor.
LESSON #1: If you decide not to get a solder mask, be sure that you have not routed signals underneath components such as inductors, which have exposed conductive surfaces.

I have so far assembled only the DC-DC convert sub-circuit, due to the majority of the components being held captive by `stores' (My departments woefully inefficient system for ordering parts). Nonetheless, what has been built, works. This surprised me! The photo below shows the current state of assembly:

1 comment:
Nice. Kapton tape is the correct stuff for that situation - much thinner than pvc tape, stronger and heat resistant. You can put it through a reflow oven, and it comes out unchanged!
eg. http://uk.farnell.com/3m/92-tape-12mm-x-33m/92-tape-kapton-12mmx33m-amber/dp/3309691
Post a Comment