Soldering PICqueño32 dev-board prototype

A video of the PICqueno32 prototype build and test process. About 70 minutes of soldering is reduced to 5 minutes.

First the big chips go down. This board has a 64pin TQFP PIC32 and a 28pin SOIC FT232 USB->serial chip. We had to salvage the FT232 from an old Bus Pirate prototype.

Next the small passive components are soldered. A spot of solder goes on one pad of every part. Parts are soldered in place on one side. When all the parts are on the board the remaining sides are soldered at once.

Connectors, headers, and through-hole stuff goes on last.

We’ll try to document all future prototype builds. The first test was rough, but it gave us ideas for next time.

This entry was posted in builds, Development, Status update and tagged .

Comments

  1. Sjaak says:

    I wish I could solder this quick :)

  2. Nice video Ian!

    Applying the flux reminded me of a personal incident which happened a couple of weeks ago.
    I used an expired Amtech paste flux, in a syringe, for assembling a hobby board of mine.
    Used IPA to clean the board thoroughly.
    No matter what i did the board simply did not work.

    After troubleshooting i realised the culprit was the flux which created shorts inspite of cleaning the board thoroughly. After I hot-air desoldered the IC cleaned the board with IPA again and used a different flux tube (from Amtech, but not past its expiry date) the board started functioning properly

    Just putting down an observation of mine so that it might be of use to other in the future.

    • rsdio says:

      Krishna,

      I never use flux, and I never use solder wick, so I stick to hand-soldering SOIC spaced SMD pins. Even still, I’ve had examples where the Eagle autorouter placed vias very close to the SMD pads but under the chip where I could not see them. Now, my habit is to use a digital ohm meter to check every pin for shorts with any other pin. If you have the Eagle layout on screen while doing this, you can highlight the trace that you’re testing to see where it might short – or, if you find a short, you can often figure out where it is (that’s the only way that I discovered the short under the chip between the pad and the via).

      In general, I would not consider gobbing on solder and using wick to remove the excess. That just seems like a lot of waste to me, and I prefer to only use the amount of solder needed. I’m convinced that solder wick could not have removed the solder bridge in the example I described above, so it seems like a less-than-perfect approach.

      In other words, your example seems to have only tried the expired and non-expired flux one time each. That’s not really enough data to make a scientific conclusion. It could have been entirely random chance that your first attempt failed and your second one was successful. It may have had nothing to do with expiration dates. This all assumes that you did not locate the exact short to confirm whether it was due to solder or flux.

      Thanks for sharing, of course, but there could be many explanations!

  3. erdabyz says:

    I wish I already had every required component to assemble mine as soon as the PCB arrives!

    But i’ll have to wait a bit.. D:

  4. J. Peterson says:

    Why not use solder paste and an oven or skillet? I find it much, much easier than trying to solder SMT ICs by hand.

    • Ian says:

      I guess I am used to it :) I like to solder everything by hand and don’t trust a prototype unless I solder every pin. Also, in my setup it takes longer to properly paste, then cleanup, the board when I do the skillet method.

  5. I really appreciate you making this video but the lighting and resolution could be way better. Interlacing is also disturbing but I understand that it’s a first step.

    • Ian says:

      Yes, video is terrible and it was really awkward to solder around it. The camera was upside down while the monitor was pointed at me, and I had to mirror it in post production to make it look “human”. Also, it is an old DV tape camera and I had to sit and wait for the video to dump in real time over firewire. The compression codec also stole about half of the brightness. Today I’m getting a couple cheap SD card cameras and it should get a lot better.

  6. Greg says:

    I’ve never thought of securing the board using blu-tac. Thanks for the tip, that will make soldering so much easier.

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