New Boards Have Arrived

July 19, 2008 | 2 Minute Read

Just received my revised Ifos circuit boards from the manufacturer yesterday, so most of the evening was devoted to assembly.

The boards themselves look great, with my corrections in place (fixing the DRC errors of the last batch) and no obvious defects.

New PCB front

The new PCB, showing mostly SMD components (this time with blue solder mask)

My plan had been to assemble only the bare minimum on the first board, just to verify functionality, but once I got started I just couldn’t stop—it was mesmerizing to see the thing coming together, and I convinced myself it would save time in the long run. (Adding the surface-mount components is certainly easier when there aren’t any larger, through-hole components in the way.) So, about four hours and 10” of solder later, I had a substantially complete prototype!

In the end, I did make a few cautious allowances.

  • I only added 6 LEDS (2 RGB and 4 white) out of 24.
  • I didn’t add any of the RS485 line-biasing components, since they’re optional anyway.
  • I didn’t add the second Flash memory chip, since the first one isn’t even used yet.
  • I only added a single LED driver chip, since the MAX6957 is expensive.

The MAX6957 was also very difficult to solder, which discouraged me from adding both. It’s a fine-pitch SSOP chip (0.65mm), which I’ve soldered before, but for some reason this one was a nightmare. I just could not get the solderwick to work for me, so ended up resorting to gentle, then slighly more forceful, then aggressive tapping of the board on the workbench (never a good idea). It wasn’t until later I realized I hadn’t used any flux on the wick. Oops.

New PCB back

Backside of the unassembled PCB, showing ground plane

Some of the through-hole parts were harder than I expected, due (I guess) to the exceptionally small pads. Otherwise, overall assembly difficulty was about what I expected. The 0603-size caps were particularly bad, but that wasn’t a surprise. With a little more practice, I think I’ll probably be able knock out a board in about 60-70 minutes.