Tag Archives: SMD


Soldering Accelerometer MMA7660 in DFN-10 package using a Hot Air Rework Station


Freescale makes some nifty accelerometer chips, like the popular MMA8452, for which Sparkfun, USA sells a breakout board. But unfortunately (for hobbyists) they all come in hard-to-solder tiny little packages, like the 16 pin QFN which is just 3 mm x 3mm across.

After a few unsuccessful attempts to solder the MMA8452 chip at home, I found a better candidate – the MMA7660 which has a DFN-10 package. As you can see from the schematic below, the latter has only 10 pins, and the pins extend to the sides, which makes it easier to solder.

MMA7660 vs MMA8452
[From Freescale MMA8452/MMA7660 datasheets, for illustrative purpose.]

I was able to successfully solder the MMA7660 on to DFN-10 prototype board using a hot air rework station.

I basically followed the technique shown in the video below:

  1. Apply flux and tin the pads.
  2. Place chip on tinned pads – align correctly, apply flux.
  3. Heat the chip with the hot air gun.
  4. Solder exposed pins on the sides.
  5. Reheat the chip with hot air gun to reflow the solder.
  6. At each stage, inspect pads with magnifier for shorts, and use flux generously.

Sjaak solders a QFN chip, attempts a BGA chip:

A couple of photos of the chip after soldering:

MMA 7660 MMA 7660 Magnified

So why torture yourself soldering these microscopic chips when you can buy breakout boards?

A few reasons to consider, especially if you are trying to make a product that you might sell:

  • Cost: The breakout board is usually 4-5 times more expensive than buying the chip.
  • Size: If you are designing a PCB yourself, it’s going to be much more compact if you just use the chip and not the whole breakout board.
  • Bragging Rights: When you walk into a bar and announce that you hand soldered a DFN-10 chip, that will surely make you popular. Right? Right? ;-)


nocte lux – A low cost motion activated night lamp

No, it’s not the $10000 Leica lens of similar name. ;-)

For this project, I wanted to try and make a simple night lamp – something that you can put under your cot and use it simply by picking it up. Useful in case you get up in the middle of the night and need a quick light. So I used a tilt switch and a 555 IC to design the circuit.

I used SMD components for this project for compactness. If you haven’t done any SMD soldering before, don’t be intimidated by it. You can solder many types of SMD packages (SOT23, TQFP, 1206, etc) using just a soldering iron with a small chisel tip, and a pair of tweezers. If you add a hot air rework station to your tools, you can even solder tiny QFN packages which have all leads under the device.

Here is a very informative and entertaining cartoon guide to SMD soldering.

Here is a video of the project:

You can find all relevant files at our GitHub link below: