Soldering Guide: Definition, Types & How to Do it?

If you were to take apart any electronic device that contains a circuit board, you’ll see the components are attached using soldering techniques. Soldering is the process of joining two or more electronic parts together by melting solder around the connection.

Solder is a metal alloy and when it cools it creates a strong electrical bond between the parts. Even though soldering can create a permanent connection, it can also be reversed using a de-soldering tool. Today, we’ll be learning all about soldering. What is it? What are its applications? How does the process go?

What Is Soldering?

Soldering is a joining process used to join different types of metals together by melting solder. Solder is a metal alloy usually made of tin and lead which is melted using a hot iron. The iron is heated to temperatures above 600 degrees Fahrenheit which then cools to create a strong electrical bond.

At its simplest form, soldering is the process of joining two metal pieces with a third type of metal, whose melting point is lower than theirs. This bonding metal is called “solder.” Think of an electric circuit, that classic look of a connective tissue on the PCB that links the circuit components together. This “connective tissue” you see is solder.

Soldering is an indispensable part of the electronics industry, where it’s the primary way to join electrical components together. It’s as equally important in making jewelry, joining pipes, air-conditioning, stained-glass work, sheet metal work, and the list goes on.

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One essential distinction to be made here is that soldering is different from welding and brazing. While all three processes have the same goal, which is joining metal pieces together, they do it differently.

According to the American Welding Society, soldering is joining metal pieces together in a temperature that’s below 840 Fahrenheit degrees. On the other hand, brazing and welding use higher temperatures and produce stronger bonds.

The main pitfall of soldering though is the difficulty of correcting its flaws. It’s like ink on paper, what’s done is done, and there is no way to fix it. That’s why it requires loads of practice to master soldering.

soldering

What Metals are Used?

Filler metals used in soldering used to be lead-based (lead solder). Due to regulations, lead-containing solders are increasingly being replaced by lead-free solders, which can consist of antimony, bismuth, brass, copper, indium, tin, or silver.

Which Flux Can be Used for Soldering?

Occasionally there will be impurities such as oil, dirt, or oxidation at the point of connection. The flux prevents oxidation and can sometimes dry clean the metal. The flux used is rosin flux which aids in mechanical strength and electrical contact of the electrical connections. Sometimes it is also possible to apply a wetting agent to reduce surface tension.

Types of Soldering

Types of Soldering

There are 3 types of solders; lead-free or without lead, lead-based, and flux. Lead-based solders are the most reliable and preferred in critical applications like medical electronics or aerospace.

Lead-free solder is very easily available for flux soldiers and electronics. It contains a reducing agent at the core, which is released during the process of soldering. It eliminates oxidation from the site of bonding.

  • Soft Soldering: This method is generally used in electronics and plumbing. It creates an electrical connection and connects electronic components in circuit boards. In all the soldering systems, it is the process in which the lowest metal melting point is what everyone uses. The fillers are generally the alloys, which often contain lead with liquid temperature under 350-degree Celsius. The lower temperature creates a strong joint while the high temperature creates a less strength and melts the bond.
  • Hard Soldering: Hard soldering forms a strong connection as compared to the soft soldering. The material that is used in this is usually silver or brass. To strengthen the connection, it requires a blowtorch to increase temperature and melt the main metal that is used to create a strong joint, called as base metal. It gets heated in a point to create a durable joint as it gets cool. It should be used with silver solder while joining parts of brass or copper.
  • Brazing: This type of soldering uses metal with a much higher melting point than those used in brazing and soldering. Similar to brazing, however, the metal to be bonded is heated and not melted. Once both materials are heated sufficiently, you can place the solder between them, which will melt and act as a binder.
  • Flux in Solder: The flux core is what you can say a coil or a wire, which is used at the site as a reducing agent. Flux is something that is released at the time of soldering. It reverses the oxidation of metals at a particular site of contact to give a clear electrical connection.

How Does Soldering Work?

The solder is melted using the heat of an iron connected to a temperature controller. It is heated to temperatures above its melting point of about 600 degrees Fahrenheit, causing it to melt and then cool, creating the solder joint.

In addition to creating a strong electrical joint, solder can also be removed with a desoldering tool.

Solder is a metal alloy used to create strong, permanent bonds. like copper connection in circuit boards and copper pipe joints. It can also come in two different types and diameters, lead and lead-free, and can also range from 0.032 “to 0.062”. Inside the solder, the core is the flux, a material that is used to reinforce and improve its mechanical properties.

How To Solder

To better explain how to solder, we’re going to demonstrate it with a real-world application. In this example, we’re going to solder an LED to a circuit board.

Step 1: Mount The Component: First, insert the cables from the LED into the holes in the circuit board. Flip the board over and bend the cables outward at a 45 ‘angle. This will help the component make a better joint with the copper pad and prevent it from falling out while soldering.

Step 2: Heat The Joint: Turn your soldering iron on and if it has an adjustable heat control, set it to 400’C. At this point, touch the tip of the iron to the copper pad and the resistor lead at the same time. You need to hold the soldering iron in place for 3-4 seconds in order to heat the pad and the lead.

Step 3: Apply Solder To Joint: Keeping the soldering iron on top of the copper pad and lead, touch the connection with your solder. IMPORTANT Do not touch the solder directly with the tip of the iron. You want the joint hot enough to melt the solder when touched. If the joint is too cold, a bad connection is formed.

Step 4: Snip The Leads Remove the soldering iron and let the solder cool naturally. Do not blow on the solder as this can result in a bad joint. After cooling, you can cut the extra wire from the cables.

A proper solder joint is smooth, shiny, and looks like a volcano or cone shape. You want just enough solder to cover the entire joint but not too much so it becomes a ball or spills to a nearby lead or joint.

How To Solder Wires

Now it’s time to show you how to solder wires together. It is recommended that you use helping hands or some other type of clamping device for this process.

First, strip the insulation from the ends of both wires that you are soldering together. When the wire is stranded, twist the strands together with your fingers. Make sure your soldering iron is fully heated and touch the tip to the end of one of the wires. Hold it by the wire for 3-4 seconds.

Holding the iron in place, touch the wire with the solder until it is completely coated. Repeat this process on the other wire. Hold the two tinned wires on top of each other and touch both wires with the soldering iron. This process should melt the solder and coat both wires evenly.

Remove the soldering iron and wait a few seconds for the solder joint to cool and harden. Use heat shrink tubing to cover the connection.

Desoldering

The good thing about using solder is the fact that it can be easily removed using a technique known as desoldering. This is useful when you need to remove a component or correct your electronic circuit.

To desolder a joint, you will need solder wick which is also known as desoldering braid.

  1. Place a piece of the desoldering braid on top of the joint/solder you want to be removed.
  2. Heat your soldering iron and touch the top of the braid with the tip. This heats the solder under which it is then absorbed by the desoldering braid. You can now remove the braid to see that the solder has been extracted and removed. Carefully touch the braid when heating it or it will get hot.

Optional – If you have a lot of soldiers you want to be removed, you may want to use a device called a solder sucker. This is a handheld mechanical vacuum that sucks up hot solder with a press of a button.

To use, push down the plunger on the end of the solder sucker. Heat the joint with your soldering iron and place the tip of the solder sucker over the hot solder. Press the release button to suck up the liquid solder. Push the plunger down to empty the suction cup.

Soldering Tools

The good thing about soldering is the fact that it doesn’t take much to get started. The following are the basic tools and materials you will need for most of your soldering projects.

1. Soldering Iron

Soldering iron is the most basic soldering equipment that is shaped in the form of a pen. This is used by beginners for DIY soldering works such as soldering PCBs and other electronic components. First, heat the tip of the iron by powering the device. Once heated, place it on the solder and melt it.

For beginners, it is recommended to use the pen soldering iron in the 15W to 30W range. Most soldering irons have interchangeable tips that can be used for various soldering applications. Be very careful when using a soldering iron as it can heat up to 896’F which is extremely hot.

Soldering-iron
Soldering Iron

2. Soldering Station

A soldering station is a complete kit that comes with all the essential tools for soldering. The common tools include soldering iron, hot air guns, and de-soldering tools. A soldering station is commonly used to solder sensitive electronic components as you can set the precise temperature of the soldering tip.

You have to plug the soldering station into a power outlet and set the temperature to the lowest. Step by step, you have to increase the temperature until the solder melts.

soldering station
Soldering station

3. Soldering Iron Tips

At the end of most soldering irons is a replaceable part known as a soldering tip. There are many variations of this tip and they come in a wide variety of shapes and sizes. Each tip is used for a specific purpose and offers a distinct advantage over another. The most common tips you use in electronics projects are the conical tip and the chisel tip.

  • Conical Tip Used in precision electronics soldering because of the fine tip. Because of its pointed end, it’s able to deliver heat to smaller areas without affecting its surroundings.
  • Chisel Tip This tip is well-suited to soldering wires or other larger components because of its broad flat tip.
soldering tip

4. Brass or Conventional Sponge

Using a sponge will help keep the soldering iron tip clean by removing any oxidation that builds up. Tips with oxidation tend to turn black and stop accepting solder as it was when it was new. You could use a conventional wet sponge, but doing so will shorten the life of the tip due to expansion and contraction.

Also, a damp sponge will temporarily lower the tip temperature when it is wiped off. A better alternative is to use a brass sponge as shown on the left.

Brass or Conventional Sponge

5. Soldering Iron Stand

A soldering iron stand is very simple, but very useful and practical. This stand prevents the hot iron tip from coming into contact with flammable materials or accidentally injuring your hand. Most soldering stations come with this built-in sponge and also include a sponge or brass sponge to clean the tip.

Soldering Iron Stand

6. Solder

Solder is a metal alloy material that is melted to create a permanent bond between electrical parts. It is available in both lead and lead-free variants, with diameters of 0.032 “and 0.062” being the most common. Inside the solder, the core is a material known as flux that helps improve electrical contact and its mechanical strength.

Lead-free rosin core solder is most commonly used for electronic soldering. This type of solder is usually made from a tin/copper alloy. You can also use leaded 60/40 (60% tin, 40% lead) rosin core solder, but this is becoming less and less popular for health reasons. If you use lead solder, make sure you have adequate ventilation and wash your hands after use.

When purchasing solder, be careful NOT to use acid core solder as this can damage your circuitry and components. Acid core solder is sold in hardware stores and is mainly used for installation and metalworking.

As mentioned earlier, solders come in a few different diameters. The thicker diameter (0.062 in) solder is good for soldering larger joint faster, but it can make soldering smaller joint difficult. Because of this, it’s always a good idea to have both sizes on hand for your different projects.

Solder
Solder

7. Helping Hand (Third Hand)

A helping hand is a device that has 2 or more alligator clips and sometimes a magnifying glass/light attached to it. These clips will help you hold the items that you want to solder while you use the soldering iron and solder. A very helpful tool for your maker space.

Helping Hand (Third Hand)

8. Soldering Safety

Now that you know what tools and materials you will need, it is time to briefly discuss ways of staying safe while soldering.

Soldering irons can reach temperatures of 800 ° F. So knowing where your iron is at all times is very important. We always recommend using a soldering iron stand to avoid accidental burns or damage.

Make sure you are soldering in a well-ventilated area. When the solder is heated, fumes are released which are harmful to the eyes and lungs. It is recommended to use a fume extractor, which is a fan with an activated charcoal filter that absorbs harmful solder smoke. You can visit locations like Integrated Air Systems for air filtration systems.

It is always a good idea to wear safety glasses if you accidentally splash hot solder. Lastly, be sure to wash your hands when you are done soldering, especially if you are using lead solder.

Soldering Safety

Tinning The Tip

Before you can start soldering, you need to prepare your soldering iron by tinning the tip with the solder. This process helps to improve the heat transfer from the iron to the object to be soldered. Tinning also helps 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 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.

Tinning 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.

Uses of a Soldering Iron

A soldering iron is a hand tool used to heat solder, usually from an electrical supply, at temperatures above the melting point of the metal alloy. This allows the solder to flow between the workpieces to be joined.

This soldering tool consists of an insulated handle and a heated, pointed metal iron tip. Good soldering is influenced by how clean the tip of your soldering iron is. To ensure cleanliness, a user holds the soldering iron firmly and cleans the soldering iron tip prior to soldering components or making the soldered joint.

In addition to the soldering iron, solder suckers are an important part of the soldering structure. When excessive solder is applied, these small tools are used to remove the solder, leaving only what you want.