An electric soldering iron is a must - have tool for electronic hardware engineers.
It's mainly used to solder electronic components onto a PCB board, for tasks like repair, verification, and analysis. So, how do we use it?
First, let's take a look at the basic appearance of an electric soldering iron.
It usually converts electrical energy into heat to heat the tip of the soldering iron head. The temperature can generally reach 200 - 500 °C. So, if you accidentally touch the soldering iron head, pull your hand away quickly (otherwise, it's like roasting your hand).
Also, after the soldering iron tip is heated, it easily gets oxidized and dirty in the air, and the next time it might not pick up solder well. So, after using the soldering iron each time, you need to dip some solder on the soldering iron head to prevent it from oxidizing.
Then, there are the essential soldering materials, that is, the solder. Usually, it's called solder wire, and now we generally use lead - free solder wire. The lead in lead - containing solder wire is toxic and not good for the human body (even though its soldering characteristics are great). Although lead - free solder wire has no toxic lead, the fumes generated during soldering are still bad to your health. Try not to inhale them. Make sure you're in a well - ventilated area when using it.
During the soldering process, we also need a flux - rosin. It can remove the oxidized layer on the solder wire or the PCB surface, increase the fluidity of the solder, and make the soldering process go more smoothly.
After getting all the tools ready, we can start soldering.
Through - Hole Soldering (Pins Connect to the PCB through Holes)
The steps are as follows: First, pass the corresponding pins of the component through the PCB board. Then, dip the tip of the solder wire in some rosin. Next, place the soldering iron close to the pin on the PCB that needs to be soldered (usually for about 1 second). Then, touch the solder wire with rosin to the soldering iron (put it under the soldering iron head or parallel to the soldering iron head, not on top of it). The solder wire will melt under the high temperature of the soldering iron head and form a drop - like shape to cover the area of the pin and the PCB board. After it melts, quickly move the solder wire away. But at this time, don't move the soldering iron head yet. Keep the soldering iron head in the original position for about 1 second to let the solder fully melt and flow around the pad and the wire, thus perfectly completing the entire soldering process. Of course, after soldering, if the pins of the soldered component are too long, you need to cut off the extra parts.
Surface - Mount Soldering
Surface - mount soldering with an electric soldering iron is usually more difficult than through - hole soldering because sometimes the components are really small, so the operation requires more precision. For example, for a 0603 - sized resistor, a more precise soldering iron head is needed, and a relatively sharp one is often chosen.
When soldering it to the PCB board, first, de - oxidize the soldering points on the PCB board. Then, use the soldering iron to pick up a small amount of solder and apply it to the surface of the PCB board. Next, use tweezers to place the 0603 resistor on the soldering point of the PCB. Heat the soldering point with solder using the soldering iron, thus completing the soldering of one point. One soldering point should be fixed, and the component can't be moved temporarily. For the other end, just do a spot - solder with the solder wire to complete the soldering of the entire 0603 - sized resistor. For components with multiple pins, I'll share that separately next time.
In terms of technique, generally, hold the soldering iron in your right hand and the solder wire in your left hand (you can also do it the other way around, depending on your preference).
After the soldering work is done, you can check the result of your soldering. A good soldering job has the solder completely covering the pad and also including the wire. This requires long - term practice.
So, what if the soldering goes wrong or fails?
At this time, you can use an electric soldering iron or a hot - air gun to remove the component from the PCB board and re - solder it. For the solder that remains on the pad in a bad state, you can use solder wick to deal with it. It can absorb the liquid solder by heating with the soldering iron, thus removing the extra solder on the PCB.
