Types Of Soldering You Should Know About

June 8, 2021

By definition, solder is a fusible metal alloy (i.e. low melting point) used to create a permanent bond between metal workpieces and any electric component such as circuit boards to create a connection, which can allow an electric current to flow.

This is widely used to create a very good electrical or mechanical very joint between two definitely certain materials by melting a lead-based solder fairly such as brass, copper, and tin.

For all intents and purposes, soldering is very important to on the whole create an essentially effective electrical connection.

If you have tried joining all the cables together and ended up frustrated for the reason that it did not work, it's because of the fact that when you perform soldering – it requires a complete and stable connection considered from various factors.

If you are confused on what to do, in this article, we are going to learn more of the details and everything that you in fact need to really know about soldering so keep reading.

Type of solder by temperature

Types Of Soldering You Should Know About
technician soldering an electrical circuit board

In this section, we will be tackling the three types of solder which use increasingly higher temperatures. This is proven to produce progressively stronger joints.

Soft soldering (90 °C - 450 °C)

This type of soldering is generally used in electronics and plumbing for it creates an electrical connection between components and circuit boards through using the lowest filler metal melting point.

These filler metals are usually alloys that are around 400°C. Oftentimes, these alloys contain lead with liquidus temperature that is below 350°C.

This process may thermally stress the components the least due to the low temperatures used in soft soldering. However, this does not produce strong joints which makes it inappropriate for mechanical load- bearing applications.

This type of solder also loses its strength and melts on the occasion of being exposed to great degree of hotness, thus disqualifying it for high-temperature use.

Hard (silver) soldering (>450 °C)

Hard soldering forms a strong joint as compared to soft soldering.

In this type of solder, brass or silver is the bonding metal that is being applied. Silver gives you a vigorous mechanical strength. In spite of the fact that it offers less ductility than metals like lead, it can heighten resistance to the fatigue from those thermal cycles of any lead-free solder.

With the use of a blowtorch in order to strengthen the connection, high temperature is to be achieved that should be 450°C or more, which these specific solder metals require.

Brazing (>450 °C)

Brazing is a popular metal joining process in which the base metal is not melted, but fused through heating up brazing rods or fillers.

Unlike those used in hard and soft soldering, this process uses a metal with a much higher melting point. However, the metal being bonded is heated opposite to being melted, which in that case is very similar to hard soldering.

The soldering metal that you will place in between your sufficiently heated base metals will melt and act as a bonding agent, thus securing you a stronger joint. 

Always remember that the material needs to be heated sufficiently to achieve the best outcome.

Type of solder by core

solder wire with acid core

The following types of solder are classified into three different types based on their type of core. 

Acid Core Solder

In this type of solder, the hollow core which consists of an acid-based flux known for its aggressiveness and strength is being wound with the solder in the form of wires. The wire is used at the site as a reducing agent.

This acid-base flux is operative to fully eliminate the metal oxide layer formed on the surface of the material. Other than that, it also hinders further oxidation of the metal. With that being said, you can be assured that the joints are solid and strong enough not to break.

Acid core solders are mainly used to fuse copper pipes and sheet metal in plumbing applications, or steel and other metals. But after soldering, it is a necessity to clean the flux residue to prevent corrosion in metals. 

Rosin Core Solder

Same with the acid core solder, this type of solder also has a hollow core present inside the solder wire but they differ in the type of flux being used which is a much milder flux made of rosin. 

The rosin core solder is advantageous when it comes to sustainability due to the fact that this milder flux does not cause corrosion. That is why this is the type of solder used in electrical appliances for the reason that it is difficult to remove the residue in electrical connections.

Sometimes, at the site of the joint, there are impurities such as oil, dirt or oxidation. The flux helps prevent the process of oxidizing on the metal surface and can sometimes chemically clean the metal itself. When rosin flux is used, this acts as an agent that enhances mechanical strength and electrical contact of electrical joints. There are also times where it is also possible to apply a ‘wetting agent’ to reduce the surface tension.

Solid Core Solder

This type of solder is very different from the two other core solders. Instead of a hollow core which is present in the two former core solders that have been given, solid core solder uses a solid wire containing the solder alloy or material.

This does not contain flux, thus requiring you to apply the flux separately in the event that you choose to use this solder.

Type of solder by alloy

The following types of solder are classified into four different types based on the type of alloy namely:

Lead Alloy Solders

soldering alloys

In this solder type, other alloys also known as soft solders are being mixed with the lead to get the required melting point and tensile strength. 

Tin is the most commonly used alloy along with the lead in this mixture.They are mixed in the ratio of 60% tin and 40% lead. This mixture will melt when it reaches its melting point of 180 to 1900C.

In light of the fact that it has a low melting point, tin is preferred among others.  Alongside with that, tin also improves the tensile strength and shear strength of the lead.

Lead, on the remarkably other hand, principally restraints the growth of tin bristles. Lead-based solders use a numbering system called the lead alloy ratio that determines the percentage of lead as well as the mixed metal in the alloy.

Common alloys that are tin solders include:

*Percentage of of tin / percentage of lead

  • 63/37
  • 60/40
  • 50/50
  • 30/70
  • 10/90

Lead-Free Solders

You will surely know from it's name that these types of solders do not contain any lead. These lead-free solders have a higher melting point compared with the lead alloy solders.

In the U.S.A, you can get tax benefits if you use lead-free solders. This is due to it's poisonous content towards your health and the environment. That is why the federal government of America provides incentives to manufacturers that choose to use lead-free solders.

Rather than using nickel, you can use additives such as nickel and conformal coatings to avoid tin whiskers.

Some examples of lead-free solder include indium solder, spelter brass solder which is pure zinc or a zinc alloy solder, platinum solder, gold solder, and silver solder  which are higher temperature solders used as jewelers’ solder.

Flux-Core Solders

The flux core solder is present in the form of wires coiled on a cylindrical device that acts as a reducing agent present at its core.

In the process of soldering, the flux is used to remove the oxidized layer formed on the surface of the metal that can cause corrosion if left uncleaned. As a result, the metal surface becomes clean and ready for soldering.

Apart from the benefit of removing the oxidized layer, it also adds on the solder’s wetting properties. When you intend to solder electronic components, rosin is used as a flux. For metal joining, fusing and plumbing, acid cores are used as a flux.

Silver Alloy Solders

silver soldering

Back in the old days, silver was only added to lead based alloy solders. This is to hinder an effect called silver migration. But at this point in time, silver alloy solders can either be lead-free or lead-based solders.

The silver that can be found in the silver plating gets into the solder. If this solder is put to practical use in the metals before soldering, it makes the joints weak and prone to breaking.

The silver alloy solders come in different ratios of silver, lead, and other alloys. The price of these various types of solders varies on the ratio of these alloys.

Types of solder by form factor

The solder form is to definitely be determined based on the type of application and the type of sort of metal to be soldered.

There are various types of solder according to form factor. Here are as follows:

  • Solder wire - the most common form of solder where the solder wire is wound over a spool.
  • Solder strips - Also known as solder ribbon. This is a soldering material that's made into a strip-like form.
  • Solder pellets - Also known as slugs, solder pellets are often used to join pieces of metal. This cost effective method for connecting electrical terminals to wire shortens the need for time-consuming crimping processes.
  • Solder rods - The very common form of solder used by almost every welder in most cases.
  • Solder bars - Solder bars melted into solder pots can be a faster, more automated method of soldering than hand-soldering with solder wire. Tri-Bar is a stick of solder that can be hand-held to provide a larger volume than wire solder with reference to making soldered sheet metal seams. 
  • Solder washers - These are pre coated washers that can automate the soldering process for through-hole components special cases in electronics.

Types of solder by application:

pipes

Plumbing

Good plumbing can prevent cross-contamination, hence keeping the water in your home pretty clean and safe at all times, for all intents and purposes.

This specifically is where soldering comes into the picture in a generally big way. It ensures that there are no leakages or any unresolved broken pipe lines by joining together copper pipes. This certain dillemas can cause  bigger damage and health risks when left unattended. 

Electronics

Soldering is essentially used in the electronics industry. This could be electrical appliances or anything that definitely needs connection between the component and the circuit board such as joining copper to printed circuit boards which literally is fairly significant.

Aircraft solder

Aircraft manufacturing and repair needs to specifically meet the specific needs of environmental conditions that involve vibration and thermal cycling in a definitely big way. This is where aircraft solder is exclusively used. 

Automotive solder

Soldering in the automotive industry is used to repair leaks that essentially develop in the coolant heat exchangers of cars and basically other motor vehicles, which is definitely contrary to how good vehicles and their machines should be..

Household repairs

Household repairs most of the time need soldering, or so they thought. Damaged electricity wires, broken very metal items or even the leakage on your sink, basically soldering for fairly sure comes very handy in a major way.

Conclusion

In the final analysis, there are sets of factors to consider upon choosing the right type of solder to use in order for you to attain satisfactory quality of outcome. 

As a matter of fact, there are sorts of alloys or materials used to produce solders for distinct applications. Basically, the proportion of elements used in solder alloys will be dictating the solder’s melting temperature which then aligns to the possible applications and intent use for that solder.

With that being said, it is safe to say that soldering can be quite tricky at first but when you are eager to learn and understand the process and the factors that come along with it, success is surely attainable!

It is our utmost desire to help you start up and improve your soldering journey. 

We really hope that we have been able to help you answer all your queries and doubts with regards to soldering. 

Resources:

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