While taking stock of the components I had on hand last weekend I found a small box of sample components that I had ordered from Maxim a while back; Two each of several components: DS2717 RTC, DS2438 Smart Battery Monitor, DS2762 Hi-precision Li+ Battery Monitor with Alerts, and an DS2408 8-channel addressable switch. These parts all have a couple things in common – first, they are all 1-Wire devices, but more to the point they are all surface mount components. The 2717 is a TSOC-6, the 2438 is a SOIC-8, the 2762 is a TSSOP-16, and the 2408 is a SOIC-16. And they are *tiny*. Seriously. My renewed interest in electronics and the Arduino spurred me on to research whether hand soldering was even possible with these parts, and I was pleased to discover that not only is it possible, it’s really quite easy as long as you use decent tools and follow a few simple guidelines.
I really wanted to use the DS2438 in my project – battery monitoring, temperature measurement, and analog measurement in a single, tiny, low-power-consuming device is a really great combination for a remote wireless sensor. After a bunch of extremely frustrating online searching and research I finally stumbled upon Proto Advantage, a little company out of Ontario, Canada. The company sells a huge number of adapters and other devices useful for prototyping, but what caught my eye was the clear instructions and videos showing how to deal with these tiny components.
My early experiments with SMC soldering didn’t end well – I was using a cheap soldering iron and attempting to solder leads directly to the tiny device. This was NOT a recipe for success; I destroyed the poor little chip and put my collection of devices away for a rainy day.
There are a few must-haves before attempting this. At a minimum, here’s what I’d recommend:
- A Helping Hand With Magnifier to hold the work piece steady and give you a bit of magnification in the process
- A decent Adjustable Soldering Iron with a 1/32″ chisel tip
- A liquid flux pen
- Curved-tip, ESD-Safe Tweezers
Some other items that are nice to have but not absolutely necessary:
- A Panavise Junior instead of helping hands. More expensive, but a bit more stable.
- A Vacuum Pickup Tool for handling those tiny components
- A Dry Tip Cleaner for keeping the soldering tip clean
- A 5x Magnifying Lamp makes life a lot easier too (unless your one of them young’ins, in which case get off my lawn<g>)
You don’t have to spend a fortune to do this, but two things are absolutely critical: first, invest in a decent soldering iron. Not everyone needs a $500 Hakko soldering station, as nice as it may be, but the $5 Radio Shack iron that you inherited from Dad ain’t gonna cut it. Trust me, spend the money and you’ll thank me later. If you’re on a budget, adafruit sells a very, very nice unit for about $20 – this is what I used until very recently when I upgraded to a Weller WES51. If your soldering iron is too hot, you will just end up destroying components and/or lifting pads off of the breakout board.
The second critical piece is a flux pen. This process just won’t work well without it.
The process itself is quite simple:
- Place the breakout board in the helping hands; you will want magnification for this!
- Place the SMC component on the breakout board, making sure that it is properly centered and that the leads are correctly touching the pads of the breakout board. USE YOUR ESD-SAFE TWEEZERS for this.
- Damp the leads of the chip with the flux – it’s OK if it seems like a bit too much.
- Double-check the position of the chip.
- Tin the tip of the iron with a small blob of solder; a bit more than just lightly tinned, but less than a droplet; these leads are tiny, and it doesn’t take much.
- Touch a lead in one corner of the chip with the flat side of the tip near the body of the component and lightly drag the iron to the end of the lead, then remove the tip.
- Wait a second – the solder should have flowed over and around the lead. Once the solder joint is cool, proceed with the other pins.
That’s it. Solder is really magical stuff, I’m always fascinated by how it flows. Clean off the excess flux and examine the leads under magnification – the solder joints should appear clean and shiny. If you see any solder bridges between pins, use a bit of soldering braid and a clean tip, remove the solder, apply more flux and try again.
Once you get the swing of things it’s an incredibly easy process. I mounted all eight of the devices that I mentioned earlier on SMT to DIP breakout boards in well under 10 minutes.
Now that the devices are on DIP breakout boards, they can be installed on protoboard, breadboards, or used just like any other through-hole components. Pretty cool.
Being able to work with surface-mount components opens up tons of opportunities for working with new devices; there are a LOT of ICs that simply are not available in larger DIP packages. More and more hobby retailers are beginning to realize this fact, and are beginning to offer breakout adapters to support these packages – sparkfun, adafruit, and many others have lots of new offerings in this area. Don’t be afraid to experiment, stay safe, and have fun!