e-Gizmo Mechatronix @ Blogspot: SMD components Hand Soldering Technique

Electronics PC boards assemblies are fast switching towards the use of surface mount devices (SMD). SMD based assemblies have a number of advantages. Most obvious example of course is the small size. You can pack more component and features in a small volume of space. Other advantages would make a long list, so let me just wrap this up by mentioning the important fact that designers and manufacturers had taken notice. It is happening now, SMD is the component of choice for new designs.

With this development, through hole components are now on a path towards obsolescence. These are already getting harder to find each days.SMD components are the parts of the near future, yet hobbyists would still not dare to use these in their projects because of some unfounded myths, like that of SMDs requiring expensive specialized soldering tools to work on, coupled with a silly notion that SMDs are impossible to solder by hand.

In this photo narrative, I will show you how to hand solder SMD devices using just an ordinary iron and a pair of tweezers. We can use SOIC device for our exercise… now, that would be too easy. Let’s opt instead for a SSOP device.

Equipment needed:-15W soldering iron. A 10-60W temperature controlled iron is an excellent choice.
- Pair of tweezers
- Solder wick

Prepare the PCB by applying a dab of solder on one corner of the IC solder pads.

Using a pair of tweezers to hold the IC, position the IC and align its pins with the solder pads. Fix it in place by soldering the pins on the pre-soldered corner. Do not let yourself be bothered by solder bridging. We will deal with it later.

Solder the opposite side with a liberal amount of solder. You can’t fight solder bridging at this time, just make sure the IC pins stays aligned with the solder pads while letting the solder wet all IC pins and pads.

The soldering job may look like this after. Trust me in saying you are doing a good job so far. Solder the other side in a similar manner.

Now you are ready to remove the excess solder and solder bridges. Grab the PCB with your hands, holding it firmly along its edge. Make the PCB droop at an angle, and then reheat the soldered joints of the IC. When the solder melts, gently slide down the soldering iron towards the lowest pin. You should see the capillary action, aided by gravity, removing the excess solder and bridging. Work your way down towards the lowest IC pins, removing as much excess solder as possible. You may find excess solder on the last two or three pins stubbornly cling on. A solder wick will remove them just as easy shown in the next step.

Get rid of the remaining stubborn solder bridges using a solder wick. Apply the wick over the problem area, and heat the wick with your soldering iron. Slowly pull the solder wick away while the melted solder is sucked by the solder wick.

Remove the excess solder on the other side of the IC using the same procedure. The job is done when all the excess lead is successfully removed.

Once you got the hang of it, you will find soldering SMD components easier and more convenient compare to their leaded counterparts. While we are at it, might as well show you how to solder SMD chip components as well.

In this bonus photo narrative, we will show you how to solder chip components using a size 0805 chip capacitor as an example. The chip capacitor is shown in this photo held by the tip of the tweezers.