Are you worried about not being able to solder the surface mount components onto the MAVRIC-IB and MAVRIC-IIB board(s)? If so, please read the following quick tutorial. I was worried about it too, but with a few simple techniques and the right tools, anyone can do it.

Soldering the ATmega128

The following video demonstrates the technique. Click on the image below to view the video (4.3 MB).

The basic technique for soldering the ATmega128 TQFP package as well as SOIC and other SMD chips is as follows:

  • Use small diameter solder - 0.015 inch diameter works well most SMD parts. The solder I use is Digikey part #KE1303-ND.

  • Next, make sure that your soldering iron is hot enough. If the iron is not hot enough, you will have trouble.

    While not absolutely required, a good temperature controlled iron can make the process easier. You don't have to pay a lot of money for one, the one in the photo here was found on e-bay for a good price. Expect to pay around $40 to $100 or so new.

  • Carefully position the ATmega128 over the pads.

  • With the ATmega128 in position, keep it in position with your finger. Use flux to wet the one or two sides of the TQFP package that you can reach without lifting your other finger. Heat several of the pins on the part to tack it in place. Because of the flux, the existing solder on the PCB pads will wick up on the leads and hold them in place temporarily.

  • You can now lift your finger. Apply flux the other side of the chip. If it's a quad chip, flux the other three sides. Using the small diameter solder, lay the solder right across all the pins of a side so the solder is on top of the pins parallel to the chip edge. Drag the hot iron across that row, contacting both the solder and the leads (lightly). You have to have the flux on there otherwise it won't work very well. Physics is a wonderful thing - just the right amount of solder will flow around each pin, the flux is the key.

  • If you do happen to cause a solder bridge, just add a bit more flux, sponge off your iron, then use the iron to wick up the bridge. Alternatively, just drag the iron over the bridge and redistribute its solder across the other pins or dump it into a nearby via, no need for solder braid.

  • Repeat for the other chips on the board. The same technique works with the SOIC chips and other pinned SMD packages.

Soldering 0603 Sized Surface Mount Resistors and Capacitors

The 0603 sized surface mount resitors and capacitors are quite small but they can be easily soldered by hand. I've found that the easiest way to solder these is as follows:

  • The cap we'll solder is capacitor C3 on the MAVRIC board located below. This is a 0603 sized .1uF bypass cap for the DS1307Z real time clock.

  • Begin by preparing one pad by melting a small amount of solder onto it.

    This will create a raised nub of solder on the pad as shown.

  • Next, use tweezers to position the cap over it's location:

  • Use the fingernail of the index finger of your free hand to hold the part in place while you heat the solder nub that you created a moment ago:

    The solder nub will melt and the part will sink into position and be held securely:

    Be sure and use your fingernail which has no nerves and you won't burn yourself. If you have really short fingernails, perhaps use an exacto knife to hold the part in place for this step.

  • Now just use your iron and a small amount of solder to solder the other end:

  • Finished:

Notes for Success
  • Use your solder sparingly, it only takes a small amount per pin. Bridging is the result of using too much solder.

  • Use a small diameter solder (0.015 inches is good) for the small pins. It is much easier to control the amount of solder being applied when using the small diameter.

  • Iron temperature plays an important part. If your iron is not hot enough, the process will be very difficult. However, don't get it too hot, otherwise you could damage the part. I've found that 630 to 680 degrees F works well for my iron, but the ideal temperature will probably vary from iron to iron and even the type of solder used. It may be a good idea to give the part a short rest for a few seconds every few pins to cool down a bit.

Using these simple techniques, you can successfully mount the SMT parts to the MAVRIC-IB and MAVRIC-IIB boards and save a few bucks.