Introduction: SMD Soldering on DIY LED Chaser Kit

In spare time I conduct Basic Electronics Workshops for children up to class 6th to 12th. During the workshop I use breadboard, jumper wires, components and teach them how to interconnect wires after understanding the circuit diagram. Generally, I start from LED Chaser circuit using 555 and CD4017 ICs. After the workshop, children use the same components to construct other projects on same breadboard. But what happens after making a successful circuit on breadboard? Ultimately to construct it on PCB by soldering components I was looking for a DIY kit and found this one on AliExpress which costs just INR 29 (~.49USD).

Step 1: The Kit, the Components and SMD @ Home!

The DIY LED Chaser kit arrived in about one and half month from china. But the kit came with SMD components. The components which are not soldered through the PCB but on one surface of the PCB (i.e. Surface Mounted Devices). There size was also microscopic, smaller than mustard seed. Some how I have to do the SMD soldering at home!

Step 2: SMD Soldering

It was very difficult to solder these microscopic components on given PCB. It would have required 1mm soldering tip and 0.5mm solder wire. I sharpened my soldering iron tip like pencil using some abrasive paper and started soldering. The 555 IC first. I have observed that when I have applied solder directly to IC pins and the pad, it created a blob which shot circuit adjoining pins. After 4 or 5 solders I realized that it will require very small amount of solder on tip and just touch it to solder pad far from pin and it started flowing towards the pin and rest of the work done by surface tension. Wow!

Step 3: More SMD. Ever Time More Cleaner and Precise

Practice makes man perfect! As the things progressed, I started getting more cleaner and precise solder joints.

Step 4: Finally All Small Componets Done.

Finally all small components were done. Now is the time for larger ones, LED, Pot and power supply pin out.

Step 5: Mounting LED

All the components soldered. Take a proper visual inspection for short circuit and missing solders and power up the board.

Step 6: Success!

In first shot the board was working properly. It just cost me INR 29 (0.42US$) where as the breadboard and other individual components costs me INR 210 (3 US$). But the later one is more suitable to educate children. This one is just to show them how the final products are made after prototyping.