Electrical wires are part of every electrical circuit. They carry current (in the form of electrons) that power all electrical and electronic devices we use today.

But, why is solder used for joining electrical wires? Solder is used in joining electrical wires to create a permanent bond between them Also, solder is made of a conducting material that allows current to flow between electrical wires. There are many different types of electrical wire, as well as solder that is used to join them. 

Main purpose why solder is used for joining electrical wires

Electricity (electrical current) is the flow of electrons in an electrical circuit. It is what powers every electrical device from Lights, Motors, Microwaves, Televisions etc.

This flow of electrons requires a path to travel in a circuit to get from one component/device to the next. However, electrons can only flow through conducting materials like metals. An insulator like plastic will inhibit the flow of current. 

Electrical wires are composed of conducting materials that allow electrons flow in a circuit. 

There are many different types of electrical wires that range in materials, core diameter, and number of strands. 

Where does solder play its part?

Some of the time you will need to join two pieces of electrical wires to complete the path to allow current to flow. 

Solder is used to create a permanent connection between these two wires while allowing current to still flow.

A deeper look at solder

So, what is solder?

Solder is a material that in most cases is an alloy which has the ability of joining electrical wires. 

A soldering iron is needed to metal the solder that can then adhere to the pieces of electrical wire being joined together.

Different types of solder used for joining electrical wires

There are many different types of solder available, that are made using a number of different conducting materials. 

Traditional solder was lead based (made with lead). However, the use of lead based solder proved very dangerous as it creates fumes that are detrimental to a person’s health.

It can cause health problems that relate to the reproductive system, digestion, memory, and muscle/joint pain.

Due to this, regulations have been put in place to replace lead based solders with Lead-Free solders. 

These lead-free solders contain materials such as Antimony, Bismuth, Brass, Copper, Indium, Tin and Silver. 

They come in a variety of diameters as well. The larger diameters are better for larger joints, while smaller diameters are suitable for smaller hard to get joints. 

Is solder used to join wires in electronic applications as well?

Electronics is a sub-category of Electrical Engineering which also deals with the flow of currents. 

Electrical applications are of higher voltages and currents, electronic applications deal with lower voltage and current applications. 

While the wires used in electronics might vary due to the lower currents, solder is still used as a bonding agent to join wires. 

The only thing that will vary will be the type of solder used.

Best solder for joining electrical wires?

Since there are so many different types of solder available, which is the best for joining electrical wire.

The most commonly used is a lead-free rosin core solder which is typically a Tin/Copper alloy. 

If you opt to use a lead based solder, the 60/40 (60% tin, 40% lead) rosin core solder is your best option. 

However, when using lead based solders, remember to follow safety practices such as having proper ventilation, and wearing a face mask.

Other considerations to make when choosing solder to join wires, is to make sure they are not acid core as they can damage your circuit and components. 

Is there a substitute for solder to join electrical wires?

There might be instances where you have run out of solder, and need to join two electrical wires. 

Is it possible to join two wires without using solder?

Yes. You can join electrical wires if you do not have solder. 

Common ways to do so are:

• Twist the stripped ends of wires together or
• Use electrical tape to create a bond between the stripped ends. 

However, if the electrical wires carry high currents, it is not advisable to make bonds using the methods mentioned above. 

These should only be used for temporary purposes only, like if you are testing the functionality of the circuit. 

They should never be used as a permanent solution. 

Advantages of using solder to join electrical wires

The most common advantages of using solder to join electrical wires is that it creates a long lasting bond, and it allows current to flow as it is a conducting material. 

It is a better option compared to the alternatives that I mentioned above (twisting the wires and electrical tape). Using these temporary methods does not create a good connection between wires and has the potential of falling apart. 

Using solder will avoid these downfalls.

It also has many other advantages which include:

• Low power required
• Low process temperature 
• No thermal distortions and residual stresses in the joint parts
• High variety of materials may be joined
• Low level of skill required 

What is used to melt solder to join electrical wires?

So, solder is the ‘glue’ that is used to connect electrical wires together. But,what is the process of joining wires?

Soldering is the process that is used to join electrical wires. The solder needs to be melted in order to join two pieces of electrical wire. It needs to be heated up to temperatures around  441 degrees fahrenheit ( 227 degrees celsius). 

The way it is heated to these temperatures so it can melt is by using something known as a soldering iron. A soldering iron is a very useful tool used a lot in the Electrical and Electronic Field. 

Is solder only used for joining electrical wires?

You might assume that solder and soldering is only used for joining electrical wires and wiring components in electrical and electronics applications. 

While it’s mainly used in these fields, solder and soldering is very versatile and can be used in other applications as well. 

Other soldering applications include:

• Plumbing
• Jewelry
• Sheet Metal work
• Stained glass work

Since the sole purpose of solder is to be the ‘glue’ between two pieces of metal, applications where metal pieces need to be joined together can use solder.

Can solder be used for welding applications?

I mentioned above that solder can be used for applications where metal pieces need to be joined. 

However, this is only applicable for smaller pieces of metal. 

There are instances where larger pieces of metal need to be connected. Solder will not be suitable for these applications. 

This requires a process known as welding. Welding is similar to soldering in its processes. It uses a filler bonding material (similar to solder) and high heat to melt it to join two pieces of metal together. The main distinction is that welding uses higher temperatures and melts the base metal as well. 

Is solder used for DC and AC applications when joining wires?

We now know that solder helps create strong bonds and help current flow between two wires that are joined together. 

But, there are two types of current used to power devices ; Alternating Current (AC) , and Direct Current (DC).

Alternating current is charge that changes its directions periodically. It is most commonly found in electrical applications. 

Direct current, on the other hand, is a charge that only travels in one direction. It is commonly found in electronic applications. 

Solder can be used in joining wires that carry both AC and DC types currents. 

The only considerations that need to be taken into account is how much current travels through these wires. Higher currents will require larger diameter wires. Therefore, larger diameter solder will be needed to create a stronger bond, and be able to handle these high currents. 

Is the bond of solder permanent when joining electrical wires?

Solder is used to create a ‘permanent’ bond between electrical wires. But, is this bond really permanent?

The bond that is created by solder between electrical wires is permanent but reversible. 

The removal of solder between electrical wires and components is known as Desoldering. 

There might be a faulty wiring in a circuit, or you might have soldered the wrong wires together. You do not have to worry as you can remove the solder and start again.

Tools used to desolder include:

• Solderwick
• Desoldering pump

For a comprehensive guide on how to desolder check this article.

Tips and Tricks on how to solder electrical wires

Using solder to join electrical wires can be cumbersome and annoying at times. But, there are tips and tricks you can use to make the process less stressful. 

These tips and tricks will also help you create stronger bonds that will last longer and let current flow better.

Check the video below on how to solder electrical wires.

The post why is solder used for joining electrical wires? appeared first on Electronic Guidebook.

It is the process of joining metals together which provides a permanent hold which is also reversible.

In plumbing it is used as a connection between copper pipes, electronics to secure components and connection purposes in jewelry.

Flux is like solering’s sidekick. It is a cleaning agent used to clean surfaces to remove oxidation, to provide a better means of soldering. 

But, is it essential? Can you solder without flux?

Yes, you can solder without flux. While it is helpful in the process of soldering as the flux helps break down the oxides on the metal, it is not needed. Also, most solder nowadays come with a rosin core which does the job of flux helping breaking down oxides.

It depends on many variables such as, what the application is, whether the solder you are using already contains flux or not etc. I will also cover the benefits of using flux.

Soldering and Solder

Before we dive into whether you have to use flux when soldering, let us learn the basics of soldering.

Learning the basics behind soldering will help to better understand the importance of flux later on.

Also, I will cover solder and what it is made of, as well as different types of solder.

What is Soldering?

Soldering in its most basic definition is, when two or more items are joined together. These items are commonly metals.

A soldering iron is a piece of equipment used in the process of heating solder (a metal alloy usually made of tin and lead) to join these metals. 

The soldering iron is heated to temperatures ranging from 200 – 600 degrees Fahrenheit ( 95-315 degrees Celsius) in order to melt the solder. 

Soldering irons come in  a range of prices and qualities. When buying a soldering iron, it is best to spend money on high quality ones, as lower quality soldering irons sometimes have trouble melting the solder. 

Welding is sometimes confused with soldering. However, these two processes are quite different. 

The main difference between them is the melting process. In soldering, the metals involved are heated but never melted. With welding, the base metal is melted.

Types of Soldering

When it comes to soldering, there are three categories or forms of soldering ; Soft soldering, silver soldering, and brazing.

As we advance from one form to the next, the temperatures increase as well as the strength of the joints. The lowest temperatures start with soft soldering, then silver and finally brazing.

The temperatures increase due to the melting point of the filler materials.

Soft soldering uses a tin and lead alloy as a filler. Silver soldering uses an alloy containing silver and brazing uses an alloy that contains brass. 

It was common in the past for solder to only be lead based. But, due to environmental and health concerns the use of lead free alloys is more common.

Applications of Soldering

As we saw the soldering and solder are used in order to join metals. 

It is utilized in many jobs. The most common of them which you might be more familiar with is in electronics. 

Apart from just electronics, soldering is used in plumbing, metalwork, flashing and in industries involving jewelry and musical instruments. 

In electronics soldering provides connection between electronic components also allowing the flow of electricity. It is an essential part of electronics. 

Plumbing requires a secure, permanent but reversible connection between copper systems. Soldering provides exactly that. 

Jewelry and musical instruments use a combination of silver soldering and brazing in their assembly as well as repair. 

So you can see soldering plays a crucial role in many areas.

Solder

As I briefly mentioned, solder is a filler material used in the process of soldering.

To create permanent but reversible bonds between metal pieces, solder is used. It is a fusible metal alloy. It is a key element in the process of soldering. 

Having a great mechanical joint is crucial and having a great electrical joint in electronic applications is a necessity. Without a strong electrical joint, electricity will not be able to flow rendering the circuit and those components useless. 

 Solder traditionally was used in the electronics industry. It used a blend of Tin and Lead.

Types of Solder

However, as I mentioned the different applications, there also exist different types of solder. 

With many things there comes an abundance of choice. The same goes with the choices of solder. So picking the right solder can be confusing. 

Fortunately for you and me, there are three main categories that solder falls into.They are Lead based, Lead Free and Flux Core solder.

The first type of solder was the traditional solder used for electronics and  contained 60% tin and 40% lead. This type of solder has a low melting point ranging from 356 – 374 degrees fahrenheit (or 180 – 190 degrees celsius). This type of solder is often referred to as soft solder and is commonly used with soft soldering. 

Second on the list is a Lead Free Solder. After a while, the health risks and environmental effects of lead in consumer electronics was known to be negative. So having lead based solder was not the ideal situation.

Due to this, a Lead Free solder was created and Lead based solder banned from being sold commercially. 

Lead free solder usually contain 99.3% tin and 0.7% copper with higher melting temperatures around 422 degrees Fahrenheit (217 degrees Celsius).

The final solder, and most important to the question at hand (can you solder without flux) is Flux Core solder. This solder has the flux embedded in the solder and does the job of what flux does without needing to apply it externally. 

I will cover the benefits of this type of solder later when I discuss whether you can or cannot solder without flux. 

I mentioned above about two other techniques of soldering which included silver soldering and brazing.

For silver soldering, silver solder is used which is an alloy that contains silver and another metal ranging from copper, zinc, nickel , manganese, cadmium, tin, silicon and many others.

Brazing uses solder that contains metals including gold, silver, copper, brass and iron.

Solder Sizes

With different types of solder also comes different solder sizes. The size of the solder is determined by its gauge. The gauge is effectively determined by its diameter.

Different gauges of solder will be beneficial depending on the application.

When it comes to electronics work, the smaller the gauge size the better. 

Applications involving plumbing on the other hand would require a larger gauge solder. 

So, depending on the application you are using solder for will determine what size solder you will need. 

Flux

As we saw that soldering plays a vital role in many applications and solder is an essential part in the soldering process. We cannot have one without the other.

But, where does flux come in? What is its role? And is it really needed when you solder?

Let’s learn a little about flux.

What is flux?

Flux is a water based solution that contains a cleaning agent, activator and wetting agent. 

It has many functions that are used when soldering. It has to spread on the metals being soldered, it has to clean the surfaces and help spread the solder.

For a flux to be effective it has to satisfy all these three criteria. 

The first being a spreading on metals is known as wetting. Fluxes contain a wetting agent that allows the flux to flow better. The flatter the wetting the better as this will cover more surface area. 

Consequently, the better the wetting agent will result in the flux being more efficient. The more efficient a flux results in less solder having to be used and thus less cost (because you will have to buy less solder).

Next is cleaning of the surface. 

Most metal surfaces have a lot of build up of oxides, oil and dirt. Trying to solder metals that are dirty will not create a secure long lasting bond. 

So, fluxes also have the added benefit of cleaning these metal surfaces. The activator package of a flux is a specific chemical designed to remove oxides, oil and dirt.

The flux is acidic in nature because acids are great at removing oxides by converting them to soluble salts.

A great analogy here is the use of detergent in removing grease and grime from your dirty dishes. 

Detergent’s were created to do a job that water by itself would not be able to do. Imagine having to wash your dishes with just water alone. It does not have the chemical attributes of a detergent to remove all that dirt.

Dissolved oxides and dirt are then moved away by the flux leaving the metal surfaces clean. 

Another important role a flux plays during the cleaning phase is to protect the metal from re-oxidizing. After the metals are cleaned they are exposed to oxygen in the air. 

The activator package (which is rosin based) stays active throughout the entire process thus protecting the metal from re-oxidizing.

Finally, flux should promote a good flow of solder. You will know if you have ever tried soldering how annoying it is when the solder just does not stick or flow well and create good joints.

A good flux allows the solder to flow well by lowering the surface tension between the metal and melted solder.

Different types of flux

The flux you use will depend on the application. There are two main applications which include Industrial, and Electronics.

Industrial Applications include  plumbing, roofing, automobile, where metals like copper, brass, steel, stainless steel, Aluminum and Aluminium alloys are used.

Electronics Applications use three standards of flux ; rosin, water soluble and no clean fluxes.

Rosin Flux  is a natural based resin that is derived from the pine tree. There are three types of rosin flux. They are divided up based on how active they are (resulting in a cleaner surface and more residue). 

Rosin (R)  is the least active followed by Rosin Mildly Active (RMA) and finally Rosin activated (RA) being the most active.

Water Soluble fluxes are composed of organic materials and are also sometimes referred to as an organic acid flux. It has good flux activity and a great wetting agent. 

A No Clean flux has its description in its name. It does not require any cleaning after soldering.

Can you solder without flux?

So, we have covered the process of soldering as well as solder (filler materials) used to bond metals together. 

Knowing how the soldering process works will give you a better understanding of whether you need flux or not when soldering.

So can you solder without flux? The best way to approach this question is to give you all of the advantages of soldering with flux.

Also, different applications will demand the use of flux more than others.

The first and most important advantage is, better solder joints. As you saw in the section about flux, its main purpose is to clean and remove oxide as well as any other impurities from the metals being joined. 

If you have weak solder joints, the metals being soldered are prone to damage overtime.With electronic soldering having a weak solder joint results in poor electrical conduction.

Next is a better flow of solder. Flux enables a better flow of solder. This has many advantages. Having a better flow of solder means having to use less solder. Using less solder has the added benefit of lowering your cost as you will be using and buying less solder.

Also, soldering at lower temperatures, solder does not melt, flow and adhere well. Using flux will help promote a better flow and alleviate your frustrations.

Lastly, allow for desoldering. If you have ever had the misfortune of having to desolder a solder joint without flux, you know how hard it is. Desoldering a solder joint that has oxidation is near impossible. Since flux removes this oxidation, desoldering will be much easier.

Also using a lead-free solder without flux is quite a challenging task. It is best practice to use flux here.

Like I mentioned above, the application will dictate if you really need flux.

If you are a hobbyist dealing with soldering electronic circuits, it will not really be much of an issue if you solder without flux. 

Industrial applications involving electronics, plumbing, automobiles, or construction and repair of jewelry will need better and more secure bonds. These can only be achieved with the use of the right flux.

If you are using a flux, make sure it is matched to the solder you are using.

Solder that contains flux

The good news is, there is a solder out there that has flux embedded in its core. This is known as Rosin Core Solder. As you saw before, Rosin Flux is a widely used natural flux.

The Kester Rosin Core Solder is a great solder which contains flux. It is the difference between good and great soldering joints.

So, for smaller electronic applications you can use this solder without having to externally apply flux and still get the same benefits. 

Plumbing solder however, does not contain flux. So, flux will have to be applied externally. 

Using flux has many benefits and will only make your life easier during the soldering and desoldering process. 

However, if you are not wanting to use flux and are soldering electronic components and circuit boards you have the fortune of having a solder that contains flux.

Soldering Flux Alternatives

Flux in its simplest definition is a cleaning agent. It’s earliest form was carbonate of soda, charcoal, borax, lime etc.

There are many options of cleaning agents you can use with common everyday house items.

If you ever want to make your own flux check this tutorial out. It’s great for the environment too!

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