Soldering is one of the most basic skills required to handle electronic projects. Although beginners can very well work with breadboards and other simple-to-operate components, once they learn how to solder, it gives them access to a whole new world of innovative ideas and possibilities.
As we have discussed earlier, the PCBs are little more complex to handle than breadboards, in the same way, soldering is also a crucial skill to learn for the beginners. This is why we have come up with some soldering tips and guidelines for the electronic engineers. So, if you are afraid to even touch the soldering iron, these dos and don’ts will definitely help you a long way in your projects.
Let’s get started with the basic understanding of the soldering procedure and the required list of tools.
What is Soldering?
Soldering: What is it and how it’s done? (Image Courtesy: Digital Trends)
Soldering is the process of joining two metal pieces by heating them to a suitable temperature. This is done by using a filler material which cools down to form a bond between the two pieces.
In order to solder the required items, one needs to be aware of the tools that are quite important throughout the procedure. These are enlisted below-
Solder Wire (Image Courtesy: teknuclei.com)
It’s the alloy that is usually available as a long, thin wire in spools or tubes. In conventional form, solder contains lead, tin, and few other trace metals. However, with the harmful effects of lead, another category of lead-free solder was later introduced which is used in certain countries.
Soldering Iron (Image Courtesy: eBay)
The most basic tool to solder components is the soldering iron. There are various types of soldering irons but the functionality is almost same in all of them. It further has different parts explained below:
Soldering Tips- Bevel, Conical, Chisel (Image Courtesy: Adafruit Industries)
Tip is the part of the iron that heats up and allows solder to flow around the two components that are to be joined. As opposed to the belief that the tip transfers the solder, it rather transfers the heat which raises the temperature of the metal components and the solder melts accordingly.
Often the tip of a soldering iron can be changed, as per the requirement. It’s mainly of three types- Bevel, Conical, and Chisel.
Soldering Wand (Image Courtesy: snapdeal.com)
This part of the iron holds the tip and is handled by the user. It’s made of various insulating materials to prevent the heat of the tip from transferring to the outside of the wand. Besides, it also contains wires and metal contacts that transfer the heat from the base to the tip. Owing to this dual role of heating and preventing burns, it is very important that you use a high quality wand.
Soldering Base- Analog and Digital (Image Courtesy: Sparkfun.com)
It’s the control box of the soldering iron that regulates the temperatures. In the analog one, it is carried out with the help of dials while there is a button equipped with the digital ones. It is basically composed of a large transformer and other control components that ease the variation of the heat of the tip.
Soldering Iron Stand (Image Courtesy: Adafruit Industries)
The stand is used to house the iron when it’s kept ideal. This is because leaving an unattended iron on the desk can cause a fire. These stands feature auto-shutoff function that reduces the temperature of the tip when the wand is kept in the cradle. This, in turn, prevents the wearing of the tip over time.
Over a period of time and with continuous use, the tip tends to oxidize and turns black, thus not accepting the solder. Also, in case of lead-free solder, the impurities of the solder build up on the tip causing this problem. This is why a sponge is used to clean the tip and prevent it from wearing off. Earlier a wet sponge was used but now a brass sponge is common.
Flux Pen (Image Courtesy: Alibaba.com)
It is the chemical agent that eases the flow of lead-free solder. It is used when certain components are too difficult to solder so as to make it look like a proper solder joint.
Desoldering Vacuum Pump
Desoldering Vacuum Pump (Image Courtesy: Walmart)
It’s a tool used for desoldering components by removing the solder left behind in through-holes.
Solder Wick (Image Courtesy: Amazon)
It is used to erase the extra chunks of solder while desoldering the components. Containing thin cooper wire braided together, this wick is placed over a connection and the opposite side is heated with an iron.
In order to ensure an effective soldering and reduce the chances of damage, there are certain soldering tips, which can be really helpful for electronic engineers, particularly the beginners. Here we are listing down some valuable soldering tips:
1. First and foremost, it’s important to understand what kind of tools you really need for your projects. As there are various varieties of tips and solder, you have to make sure that you have small tips and thin solder.
Soldering Iron Tips (Image Courtesy: SRA)
2. Before getting started with your first project, it’s better to practice soldering on some old piece of electronic equipment so that you don’t have to bear any loss.
Practice soldering on an old piece of electronic equipment
(Image Courtesy: shutterstock.com)
3. There are soldering kits available with training materials so that you can work on your soldering skills. So start with a few cheap test components into a test prototype board.
Soldering Iron Kit (Image Courtesy: feala.com)
4. Be careful while soldering PCB mounted components and IC chips as excessive heat may damage or break the sensitive part or burn up a circuit board trace. Instead of soldering the component directly, solder a socket to the circuit board and then insert the component into the socket.
Excessive heat damages a circuit board trace (Image Courtesy: Billm)
5. It’s always advisable to wear safety goggles before handling soldering because the hot solder can splash into your eyes and can cause severe injury.
Safety Goggles (Image Courtesy: mtmc.co.uk)
6. Always work in properly ventilated environment because the smoke from soldering is harmful for health, especially when it’s lead solder. Either work outside or use fans while soldering.
Practice soldering in well-ventilated area (Image Courtesy: Pinterest)
7. Needless to say, soldering irons are hot and hence you have to be careful that you don’t lay them down on your desk while it’s still heated. Spread a non-flammable material on your workspace so that the hot solder doesn’t drip down as it may cause fire.
Using non-flammable material on the solder station (Image Courtesy: WorkingSilver)
8. As mentioned above, there are two varieties of solder: leaded and lead-free. While you are free to choose any of them as per your preference, it’s important to know that even though lead-free solder is safer as it’s not toxic, the leaded one is believed to perform relatively better.
Lead and Lead-Free Solder
9. If you have an unlabeled solder and want to find out which one is leaded and which one is unleaded, just heat them up. On cooling down, the leaded solder looks shiny while the other one looks corroded.
Identifying Lead and Lead-free Solder (Image Courtesy: ChrisFix)
10. While soldering wires, use rosin paste flux to prevent the wire from getting oxidized. It’s a non-acidic paste obtained from tree sap. Coat this paste onto the wire before soldering and it will be protecting against oxidation.
Rosin Paste Flux (Image Courtesy: Amazon)
11. If you are working with thin wires and small components, a soldering iron is quite convenient to use, particularly while working on circuit boards and tight spaces. However, a soldering gun is well suited to both thin and thick wires as it’s more powerful.
Soldering Gun (Image Courtesy: Sears)
12. A soldering gun has specialized tips which cost 5 bucks each. So, if you want to use a soldering gun but find it too pricey then grab a 7-stranded non-insulated electrical wire and cut smaller strands measuring 5-6 inches long. Bend these strands in the exact same shape as the store-bought tips use the soldering gun at a much economical rate.
Soldering gun specialized tips (Image Courtesy: ChrisFix)
13. If you are working in a remote area devoid of any electricity, then you can use a portable butane torch along with an adapter that fits on the top. This device can easily melt solder.
Butane Soldering Torch (Image Courtesy: wonderfulengineering.com)
14. While using a helping hand tool to hold the wires in place, cover up the end of the alligator clips with shrink tubes. This is because the bare clips are sharp enough to cut through the wire insulation, leaving it exposed.
The end of alligator clips covered with shrink tubes (Image Courtesy: eBay)
15. In order to make the soldering tip last longer, keep it clean and also tinned. Heat the tip and add a little amount of solder to cover the tip. Then wipe it off on a wet sponge removing everything except a thin layer of solder. This would help in making the tip last longer and will also speed up the heat transfer.
Tinned Soldering Tip (Image Courtesy: Control Chat)
16. If you wish to make the soldered joint last longer (in case of wire) then rub some silicone paste on the joint and the slide a heat shrink tube. Then use a heat gun to heat the tube, starting from the middle and moving it outwards. This would remove all the extra silicone out of the tube. This would make the joint much more stable ad well as water-free.
Covering the soldered joint with heat shrink tube to make it stable
(Image Courtesy: ChrisFix)
17. Don’t touch the soldered joint until it has completely cooled down. Since the solder is still in the liquid form, disturbing the joint could create cracks in the solder or air gaps.
Cracks appearing on the solder joints (Image Courtesy: E28-535i.com)
18. Instead of dripping down solder directly on the wire, place the tip underneath the wire and feed a little bit of solder between the tip and the wire. Otherwise, the solder won’t be able to penetrate through the wire, resulting in a poor electrical connection.
Place the tip beneath the wire and feed solder in between (Image Courtesy: ChrisFix)
19. The leads at the solder joint tops should be trimmed otherwise if these come in contact with the nearby traces, a short circuit may take place.
Trimming the solder joint tops (Image Courtesy: Adafruit)
20. Always ensure that the melted solder doesn’t appear like a blob which can cause a cold solder joint. The smoother it clings to the PCB and the components, the better is the connection.
Cold Solder Joint (Image Courtesy: Allpar)
Filed Under: ARM, Tech Articles