Tuesday, June 01, 2010

I Can Has Surface Mount Electronics?

(It's goin' here 'cos it is state-of-the art. If I come up with vintage-type packaging, the finished item will be featured at Retrotechnologist).

At the Dayton Hamvention, I picked up a little kit, a "digital dial" frequency display for receivers, transcievers or transmitters. It was tiny, not terribly expensive and looked like fun.

Took a closer look at it when I got home and -- oh, horrors! -- it was mostly teeny-tiny surface-mount parts.

But why not try? Sunday afternoon, I took a deep breath, got out my second-smallest soldering iron* and the good solder, and set to. I ended up using a mechanical pencil to hold the parts in place, which makes it a three-handed operation. Next time, I'll try eutectic solder (63/37, it melts superfast), as even the small-gauge silver-bearing stuff tends to be overly gummy, and wanted to carry parts away on the soldering iron tip:

The working side.

Scale? The holes in the corners are about 1/8" diameter. The leads on the ICs are on 0.05" centers. On my monitor, the full-size image is about twice life-size.

The solder is kind of globby, I need to deflux it and some of the parts are a bit askew -- but it works!
* I own (but cannot find) a miniature Wahl/Iso-Tip, one of the best, tiniest controlled-temperature soldering irons ever made. Unlike all other Iso-Tips, it's not cordless. They're not made any more; I don't think even Wahl remembers them.


homebru said...

When I discovered that the 1/8" chisel tip on my 60 watt iron was way too big for surface mount feetsies, I grabbed some 18-gauge solid buss wire, wrapped it several times around the shank of the too big tip, and left a half-inch pigtail sticking off the end. The 18-gauge pigtail was perfectly size and heat for those little feetsies.

The buss wire is easy to clean with brush or sponge and dead cheap to replace.

wv: voriums - The place where aircraft navigation radios go to die.

NYEMT said...

Done a lot of that sort of thing doing bench repairs for a small two-way radio outfit (my side job for several years). In that scenario, usually I had to remove a faulty component and replace it with a new one. I always found my easiest route was to heat the old component while prying it gently away from the board with a very small pair of tweezers until it separated from the board. Then "tin" the pads where the component was mounted before setting the new one in place, holding it with the tweezers while heating both ends alternately to allow it to "settle" into the soldered pads. Multi-pin components like your IC are WAY harder.

Standard Mischief said...

Years past I got a Wahl/Iso-Tip cordless for Christmas. Loved that iron, but the Nicad batteries died rather quickly.

(This was before I knew how to blow out the needles in the cell with the careful application of jumper-cables and a running car engine)

Always wanted to make a wired version, maybe foot-switch activated. I liked the near zero warm-up time and the fine tip.

I've super-glued the little parts down to hold them in place long enough to solder them. But I don't have a whole lot of experiance to go on here.

Lots of people are using solder paste and a hotplate.


Have not tried that yet.

Ed Skinner said...

Get the 0.015" diameter solder.

I bought two pounds but, frankly, will never finish the first. (Want the second one?)

Turk Turon said...

Ah, the smell of hot solder in the morning!

SpeakerTweaker said...

Turk beat me to it;)

Nice work! My soldering is generally done on the big, clunky side of audio/video. I've never even attempted small parts and board-level stuff.

But I envy those that do!

MOBro said...

Cool! I know better than to even try. ;^)

Eck! said...

It much easier with the right tip and really fine solder.

Steve, KD1JV has had a load of little kits like that over the years at really great prices. I've built a few the best
was QBSA IT was freq counter, audio amp, low current variable supply and 10W digital Forward reflected power meter. I use one of them for a bench instrument as it's just way handy.

6m has been open to your area since 14:00Z.


Crucis said...

I have a neat device containing two clip-grips and a magnifying glass that I've used to surface mount works. My issue is that little quiver in my solder hand after peering through the glass for an hour soldering/resoldering those tiny resistors/capacitors/ICs onto the proper pads.

My last surface mount project was a GRP xceiver for 80Ms. Worked well with about 100mw output in a small Altoids tin.

Ritchie said...

At the laser mine, I usually do this sort of thing with Binolux type magnifier headgear. Starting with clean pads, melt a small mound of solder on one pad. Grasping the component with tweezers, expeditiously but not rushing, re-melt the solder and set one end of the comp into it, and allow to cool. Solder other end at leisure. This also works for setting ICs in place, starting with diagonal corners. And the key to removing SM parts? Add more solder. It holds the heat and allows you to melt the solder at both ends and shift the part off the pads.

reflectoscope said...

I'd say PID toaster oven reflexivly, but it looks like you're doing fine without.

To preference I'll work with crimp-together parts, but I've soldered a joint or two.


HTRN said...

Like Reflectoscope and Standard Mischief mentioned reflow soldering using hot air(modded toaster ovens and desoldering irons are two most common jerry rigged heat sources) is generally the way to go when building surface mount stuff - trying to use a conventional iron and wire solder is not something you want to do if you don't have steady hands and a magnifier, because solder bridges are really easy to do at that scale..