How to solder
How To Solder: A Beginner’s Guide
Soldering is defined as “the joining of metals by a fusion of alloys which have relatively low melting points”. In other words, you use a metal that has a low melting point to adhere the surfaces to be soldered together. Consider that soldering is more like gluing with molten metal, unlike welding where the base metals are actually melted and combined. Soldering is also a must have skill for all sorts of electrical and electronics work. It is also a skill that must be taught correctly and developed with practice. All you need is a soldering iron and some solder.
The goal of this guide is to explain how to solder electronic components, and also provide some guidance on choosing tools and materials.
What Is Soldering?
Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the workpiece. Soldering differs from welding in that soldering does not involve melting the work pieces. In brazing, the filler metal melts at a higher temperature, but the workpiece metal does not melt. Formerly nearly all solders contained lead, but environmental concerns have increasingly dictated use of lead-free alloys for electronics and plumbing purposes.
The good thing about learning how to solder is the fact that you don’t need a lot to get started. Below we’ll outline the basic tools and materials you will need for most of your soldering projects.
01. Soldering Iron
Most people opt for using a soldering iron to solder. It’s a great heat source that heats up and cools down quickly and can maintain a pretty constant temperature.For electronic circuits, you should use a 25- to 40-watt (W) soldering iron.Higher wattage soldering irons are not necessarily hotter; they are just able to heat larger components. A 40-W soldering iron makes joints faster than a 25-W soldering iron does.02. Solder
Solder is a metal alloy material that is melted to create a permanent bond between electrical parts. It comes in both lead and lead-free variations with diameters of .032″ and .062″ being the most common. Inside the solder core is a material known as flux which helps improve electrical contact and its mechanical strength.When buying solder, make sure NOT to use acid core solder as this will damage your circuits and components. Acid core solder is sold at home improvement stores and is mainly used for plumbing and metal working.03. Soldering Station
A soldering station acts as a control station for your soldering iron if you have an adjustable iron. The station has the controls for adjusting the temperature of the iron as well as other settings. You may plug your iron into this soldering station.04. Fume Extraction Equipment
Fumes created when soldering may be toxic. Fume extraction devices pull fumes from the air to reduce health and safety risks.05. Sponge/brass wool
Often overlooked, this part is absolutely critical to soldering well. Your soldering iron tip should always be shiny silver to provide the best heat conductivity and clean solder joints. To keep the tip clean you should be wiping it across a sponge or brass wool every time you remove it from the stand.
Soldering Health and Safety Tips
- Caution: A soldering iron can heat to around 400°C, which can burn you or start a fire, so use it carefully.
- Unplug the iron when it is not in use.
- Keep the power cord away from spots where it can be tripped over.
- Take great care to avoid touching the tip of the soldering iron on a power line. If a power cord is touched by a hot iron, there is a serious risk of burns and electric shock.
- Always return the soldering iron to its stand when it is not in use.
- Never put the soldering iron down on your work bench, even for a moment!
- Work in a well-ventilated area.
- The smoke that will form as you melt solder is mostly from the flux and can be quite irritating. Avoid breathing it by keeping your head to the side of, not above, your work.
- Solder contains lead, which is a poisonous metal. Wash your hands after using solder.
Tinning The Tip
Before you can start soldering, you need to prep your soldering iron by tinning the tip with solder. This process will help improve the heat transfer from the iron to the item you’re soldering. Tinning will also help to protect the tip and reduce wear.
Step 1: Begin by making sure the tip is attached to the iron and screwed tightly in place.
Step 2: Turn on your soldering iron and let it heat up. If you have a soldering station with an adjustable temp control, set it to 400′ C/ 752′ F.
Step 3: Wipe the tip of the soldering iron on a damp wet sponge to clean it. Wait a few seconds to let the tip heat up again before proceeding to step 4.
Step 4: Hold the soldering iron in one hand and solder in the other. Touch the solder to the tip of the iron and make sure the solder flows evenly around the tip.
You should tin the tip of your iron before and after each soldering session to extend its life. Eventually, every tip will wear out and will need replacing when it becomes rough or pitted.
How To Solder
Once you’ve completed the above steps, you’re ready to solder your components together. The techniques you’ll use will vary from project to project, but the basic step-by-step instructions are as follows:
- First, determine the right temperature for your project. Which temperature to use depends on the materials you’re joining and the kind of solder you’re using. As a general rule of thumb, the best temperature to use is the one that’s as low as possible while still being high enough to get the job done. In other words, if the temperature needed to do the job is 370 degrees or above, then set the temperature to exactly 370. This will help extend the life of your tools and avoid damaging any electronic components.
- Once your iron is heated to the appropriate temperature, pick up the iron by the handle in one hand and hold a piece of solder in the other hand. Hold the hot iron to the place where the two metal components will meet for about a second to heat them up. You want to heat the metal parts, not the solder itself.
- Then, touch the solder to the heated components. As the solder melts, it will flow into the gaps it needs to fill. Continue to feed in solder until a sufficient amount is melted. While you need enough to form a solid connection, you don’t want to have too much solder either. The right amount will vary from project to project. This typically won’t take more than a few seconds.
- Allow the solder to cool. You don’t need to take any action to cause it to cool. It will do so on its own and shouldn’t take longer than a few more seconds.
- Check the soldering joint for quality. A good connection will appear smooth, uniform and shiny. Make sure that aren’t any problematic gaps between the components or globs of excess solder.
Final Soldering Tips and Tricks
- When soldering wires, make sure that you don’t touch the plastic insulation as it will almost immediately melt.
- When the soldering iron is hot, oxidation will happen at the tip. Make sure to regularly clean it on a wet sponge.
- You can get a third hand (a small metal helper for soldering) to make connecting wires easier. This is especially helpful for beginners.
- When soldering components, don’t trim their legs off too close to the board because the solder joint might crack.
- Don’t heat the pads on the PCB up for too long, they might lift off and destroy the board.
- Don’t add too much solder. A good solder joint looks like a shiny cone.