A soldering iron is a hand-held tool for soldering, i.e. for making a permanent connection between two metal objects using a different metal (solder) that has a lower melting point than the components being joined. Soldering is the most commonly used method of mounting electronic components on PCBs.
Choosing a soldering iron for your electronics workshop is a very important step in organizing such a place. Many novice electronic engineers and enthusiasts ask themselves the question: Which soldering iron is the most appropriate for me and my business and how to choose the best one? There are many solutions on the market and whether you need a simple or induction iron or something more professional like a soldering station depends on your specific application.
Types of soldering irons
The first choice to make is between a simple iron (also known as soldering pencil) and an induction iron (soldering gun). There are other types of soldering irons, such as a hot air soldering iron, a gas soldering iron, or a soldering iron that is heated by a burner flame, but they have specific applications usually outside the electronics field, so we will not dwell on them in detail.
You should bear in mind that induction irons heat up much faster than simple heating irons, but if you need a more precise tool, choose a heating one. They come with much smaller and pointed soldering tips, perfect for soldering small parts, which is why these tips (or beaks) are sometimes called “needles”.
There are a number of important parameters of a soldering iron for electronics that must be taken into account when choosing a tool: power, operating temperature range, size of soldering tip, etc. The choice depends on the purpose of the soldering iron – you must consider it before making your final choice.
When choosing a soldering iron for electronics, you need to know what its purpose will be. To solder cables, you will need a different soldering iron than for SMD components.
If you need a soldering iron mainly for soldering wires, especially with a larger cross-section, then it is best to choose a tool with high power (more than 100 W) and a large soldering tip. Induction soldering irons and simple heating irons are the perfect solution in this case.
For soldering larger electronic components, especially with THT mounting, the best option is a soldering iron with an appropriate size and shape of tip. An induction iron may also be used, but the correct tip for it must be selected.
For the soldering of small electronic components, particularly with SMD mounting, experts agree that the right choice is a pencil soldering iron with a sharp precision tip.
The soldering iron must have enough power to heat the working parts to the melting point of the solder used. The solder wire used for electronics melts at approximately 180 to 230°C depending on the composition and the percentages of its different ingredients. Solder containing lead usually has a melting point in the range 180-190°C. Lead-free solders are characterized by higher melting points between 210°C and 230°C. To melt the solder, the iron must be able to reach at least these temperatures and be able to heat up the parts to be soldered to the same values.
In fact, to heat up the parts and the solder to these temperatures as quickly and efficiently as possible, the tip of the soldering iron has to reach a much higher temperature. The required value is usually in the range 260°C – 350°C and depends on the size of the tip and the thermal characteristics of the soldered parts.
Not all soldering irons have a built-in thermostat and can maintain a constant tip temperature. There are jobs where this is unimportant and reaching a higher temperature is not a problem. However, when you solder sensitive electronic parts, this is of great importance. A soldering iron without temperature control, which reaches a much higher operating temperature than necessary, can damage the soldered parts and render their soldering pointless.
If your job includes soldering and preparation (so-called tinning) of cables and wires of large cross-section, you will need a high-power soldering iron. The iron must be able to heat up a large amount of metal in a short time. It is therefore recommended to choose either a heating iron of at least 100 W, or a powerful induction iron with a transformer.
The best choice for soldering of smaller wires and electronic components is a precision soldering pencil with a fine, sharp tip and power between 30 W and 90 W. As mentioned earlier, appropriate temperature control is required to ensure operation at a stable temperature and to prevent overheating that could damage the sensitive electronic components.
If you do not need to solder sensitive elements or if you are willing to invest in a more expensive soldering iron with good temperature control, we recommend that you choose a higher power model. The more powerful soldering iron heats up faster, maintains stable temperature, and overall improves the comfort of use.
Tips – types and shapes
The tip is the soldering iron’s working interface that transfers heat to the solder and makes the parts to connect. The tip is also a supply, which requires maintenance and, after long use, replacement due to wear and tear. When buying a soldering iron, ask whether different replacement tips are readily available and whether they are easy to replace.
Soldering tips (or bits) come in a large variety of sizes and shapes. The most common tip shapes include: chisel (also known as screwdriver), mini spoon, bevel (also known as hoof), cone and truncated cone. The choice of shape depends on the specific job or, quite often, on the soldering iron user’s personal preferences. The goal is to choose a shape that comes in best contact with the parts to connect in order to transfer heat and heat them up efficiently.
The size of the tip is directly dependent on the dimensions of the parts to solder: the larger the workpiece, the larger the tip must be to transfer the appropriate amount of heat.
Part two is coming soon