Surface Mount Silliness

[martin manning]

I've been curious about this stuff so I decided to give it a try. This is a "Simon" game kit from Spark Fun that is designed for learning SMD soldering. In the middle of the pic below is the 32-pin processor, with 0.032 (0.8 mm) solder for a size reference. The smallest parts are 330R resistors like the one on the right, 0.8 x 1.6 mm. The thing has a boost converter PS, turning 1.5V from a AA battery into 5V for the circuitry, and the 22uH inductor at the upper right is part of that.

This is not hard to do, and the only special tools required are a magnifier of some sort, a flux pen, and a good pair of tweezers. I watched a few You Tubes, and in fact the booklet that comes with the kit explains the techniques quite well. Like anything, most will develop their own blend that works for them.

Spark Fun and Adafruit are two places catering to hobbyists interested in micro controllers (Arduino), micro computers (Raspberry Pi), robotics, and the like. There's a growing electronic music element too, with Moog getting in on the act with their DIY Werkstatt synth. This is the way kids will get into electronics now.

[martin manning]

The controller can be reprogrammed, BTW, since the interface pins are broken out on the board, ready for adding pin headers.

[xtian]

I love this stuff. Look at the size of the Arduino-compatible controllers you can get today!

http://www.ebay.com/itm/Pro-Mini-atmega ... 0941830171

I used a much larger, less capable model years ago to create a MIDI footswitch specifically for the EHX 2880 loop pedal.

[Aurora]

You forgot something. You also need a good temp controlled soldering station with some small tips, but not necesseary in the 400$+++ range.
SMD is no place for guns........

[martin manning]

Ah yes, you are right. I used my moderately priced Weller solder station with a small chisel tip, same as I use for everything else!

[vibratoking]

This is interesting. I thought most guys already knew how to do this. I almost never use flux. The soldering iron tip should be small enough to contact a single pin without contacting it's neighbors. Installing parts is simple.

Removing them is a very different story.

[Aurora]

I have a Pace desoldering station at my disposal, with some various special tools, but when those don't fit, I use a pair of very pointed snippers to clip each leg, and the some good solder braid to clean up the footprint...

[John_P_WI]

I have a Pace desoldering station at my disposal, with some various special tools, but when those don't fit, I use a pair of very pointed snippers to clip each leg, and the some good solder braid to clean up the footprint...

or a sharp xacto knife works too, rather mid-evil - but works.

[vibratoking]

We have a nice hot air station at work...perfection. Desoldering station is nice to. But most of these guys aren't going to have or have access to one. Snipping legs and braid to clean up is great, but the part is destroyed in the process. My main point here is that getting parts off is harder than getting them on, at least for parts with rows of pins.

[martin manning]

I found that the added flux helps the solder wick into the pin-pad interface, so much so that a tiny bit of solder can be dragged across and evenly distributed along a row of pins without forming bridges. The amount of flux contained in such a tiny length of flux core solder is miniscule. I imagine the flux pen might come in handy for reflowing solder joints on lugs, eyelets, and turrets too.

[Aurora]

I use both spray flux and a flux pen. Pace had some very good demo videos, where they show soldering large quad packs by tacking the pack down first, and then attachin a piece of solder all the way round the pack, and th other stuff on YouTube, then hot air flowing the connections. Flux is then necesseary to make the solder flow nicely. Didn't find the videos, but they are probabl somewhere on the net, along with other stuff on YouTube....