Intro: Advanced Soldering: Fast and Easy Soldering of Surface Mount Components
Easily solder surface mount components like the tiniest LEDs and SOIC sized ICs. Make your own break out boards.
As more and more DIP ICs are being fazed out, some of them are now only available as surface mount devices. Creating a custom printed circuit board for each one is impractical for the amateur robot builder or electronics experimenter. Pre-etched Breakout boards which adapt a surface mount IC to the standard .1" spacing of breadboards are available. Unfortunately, they often cost more than the IC itself.
In this instructable are some techniques for making your own breakout board using standard copper traced strip board or perfboard. Also included are some techniques for easily mounting other ridiculously small surface mount components.
The first pic shows a breakout board for a SOIC-8 sized surface mount IC.
Step 1: Materials
.015" diameter Kester 44 solder from: http://www.mouser.com/
30 gauge heat strippable magnet wire from Mouser
Heavy duty aluminum foil from WalMart
Loctite mounting putty from WalMart
Soldering iron with 1/32" tip
Brass shavings tip cleaner available from: http://www.jameco.com/
.055" spring wire or music wire to make a surface mount clamp
Step 2: Using Magnet Wire and Special Solder
There are two main difficulties with soldering very small components-- avoiding too large a solder joint which can short nearby contacts and soldering fast enough that you do not damage the component.
This Breakout board (intro pic) works well with SOIC sized ICs. This technique can also be used to mount several SOICs or other surface mount components on a project perfboard for more complex circuits. To make it easy requires two specialty items--special solder and magnet wire.
When components are very close together, it can be difficult to solder them without blobbing over and shorting nearby pads and wires. The best solution i have found is to use a small tipped adjustable heat soldering iron (1/32") and the thinnest solder you can find. Standard solder and low temp solder is usually .032" in diameter which works fine for most things. Using thinner .015" diameter solder allows you to easily control the amount of solder on the joint.
If you use the least amount of solder necessary, it not only takes up the smallest volume, but it also allows you to solder a joint as quickly as possible. This reduces the chance of overheating and damaging delicate components like ICs and surface mount LED s. You can find the .015" solder at: Mouser.com
Instead of attempting to solder a SOIC IC to thin copper traces on a circuit board I have found it easier to solder magnet wire to the IC pins. I use 30 AWG heat strippable magnet wire available at: Mouser.com. You can use regular magnet wire, but it does not strip as easily, so I prefer the heat strippable magnet wire. This wire has a coating that can be stripped by soldering it with enough heat to melt the insulation. I let a large blob of solder hang from the soldering iron in contact with the wire for 5 or ten seconds while sliding the iron back and forth. In this way I strip the insulation and pre-tin the end before attempting to solder it to an IC or other surface mount component.
Step 3: Solder to SOICs
Solder Wire to IC
Insert the edge of a small square of heavy duty aluminum foil underneath the pin you are going to solder and over the pins on either side (pic4). This will prevent the solder from flowing on to the adjacent pins. It will also act as a heat sink. Clamp the IC onto a sheet of FR-4 fiberglass or perfboard. Put a piece of the Loctite mounting putty over one end of the foil to hold it in place. The magnet wire can then be held in place with the putty and in contact with the IC pin.
Strip and tin enough magnet wire to go to all the pins. You can then clamp one wire to the board holding the IC and aluminum foil shield and use the thin solder to solder the end of the wire to the IC pin. Move the foil and repeat the process for the rest of the pins. When you're done, you should have something which looks about like pic5.
Make a Breakout Board
Solder some .1" header pins to the perfboard that has the traces drilled out where the IC goes. Glue the IC to the perfboard. When the glue is dry, bend and solder the pre tinned wires to the header pins. Try to avoid getting the wires to close to each other as that can cause crosstalk or stray capacitance in some circuits.
You could of course forget the magnet wire and simply use shorter pieces of #30 uninsulated tinned wire. The advantage of leaving the magnet wire long and insulated is that it allows you to solder to the header pins without reheating the solder joints on the IC pins. This reduces the chance of damaging the joint or the IC. After you have tested the circuit, it is probably a good idea to coat the wires with epoxy or liquid tape to increase their insulation value, reduce the chance of crosstalk, and protect them from accidental damage from handling.
Pic5b shows a Picaxe 20x-2 SOIC breakout board module. It gives you the best of both worlds--a powerful microcontroller in a small package and an easy to use plug in module.
Step 4: Soldering to the Smallest Surface Mount LED, Resistor or Capacitor
Pic 6 shows a 0603 sized LED unlit and lit which has been soldered to magnet wire.
Pic 7 shows how it was held in the putty before soldering to the pre-tinned wire.
Step 5: Make a Clamp for Holding Surface Mount Components.
Pic8 shows a clamp I made that works well to hold down small flat surface mount components when soldering them directly to a circuit board. It was made with spring wire that is sharpened to a point on one end and then bent to the form shown.
Pic9 shows the clamp in use.
pic10 shows how tight you can solder in a Picaxe 08 microcontroller in a remote control ring: