Introduction to Soldering 100

This class provides a basic overview of the principles of soldering. The type of solder and flux used during the soldering process can impact the workpiece. Soldering tools and accessories help to make soldering safe and efficient. Understanding the advantages and disadvantages of soldering can help technicians determine if soldering is the best joining process for the manufacturing task. Most industrial soldering occurs in electronics fabrication, making recognizing the different components and processes important. Soldering is a dangerous process due to its high temperatures and toxic materials, and the necessary precautions should be taken when soldering.

After taking this class, users will understand basic soldering processes, safety, and desoldering methods that contribute to successful soldering. The improper usage of solder, flux, or soldering tools can cause damage to components and harm the technician, so it is important to understand how to solder properly.

  • Difficulty Beginner

  • Format Online

  • Number of Lessons 11

  • Language English


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Course Outline
  • Soldering
  • Lead and Lead-Free Solder
  • Flux
  • Soldering Tools and Accessories
  • Basics of Soldering Review
  • Advantages and Disadvantages of Soldering
  • Electronics Fabrication
  • Soldering Process
  • Desoldering
  • Soldering Safety
  • Final Review
  • Describe soldering.
  • Distinguish between lead and lead-free solder.
  • Describe fluxes.
  • Identify soldering tools and accessories.
  • Identify the advantages and disadvantages of soldering.
  • Describe electronics fabrication and printed circuit boards.
  • Describe the soldering process.
  • Describe desoldering methods.
  • Describe the safety procedures for soldering.
Vocabulary Term


The measure of flux cleaning strength. Activity in flux determines the cleaning effectiveness and amount of residue left behind.

additive manufacturing

AM. The process of successively layering materials to make an object based on a three-dimensional computer model. Additive manufacturing can potentially be used to make PCBs lighter and more compact.


A mixture of two or more substances, one of which must be a metal. Alloys combine the beneficial properties of different metals.

automated soldering

Any soldering process that uses a specialized machine for assembly and is not performed by a technician. Automated soldering is used in the vast majority of electronics fabrication.

base metals

The metals to be fused together in a joining process. Base metals do not melt in the soldering process.


A reddish-gray metal that expands as it solidifies. Bismuth has gained popularity as a replacement for lead in lead-free solder.

brass sponge

A sponge made of thin threads of brass used for cleaning the tip of a soldering iron. Brass sponges clean without using water, which helps prevent rust from forming on metallic objects like soldering irons.


A low-heat metal joining process that uses brass in the filler metal, which is heated to liquid form and cooled to form a joint. Brazing is mainly used for plumbing applications and differs from soldering because it requires a higher temperature for melting the filler metal.

cable lugs

A device used for connecting a cable to an electrical device, other cables, surfaces, or mechanisms. Cable lugs are used to connect wires to an automotive battery.

capillary action

The process of a liquid contacting the space in a solid and moving upwards against the force of gravity. Capillary action occurs in the soldering process when solder seeps in between the metals being joined.

cellulose sponge

A sponge made from a fabricated material that consists of wood fibers. Cellulose sponges are used to clean solder off the tip of a soldering iron.


A device used to join, grip, support, locate, or compress mechanical or structural parts. Clamps are often used to hold delicate items.


A form of heat transfer that occurs when neighboring atoms vibrate against each other. Conduction occurs when a soldering iron melts the solder.


Able to effectively convey heat or electric current with low resistance. Soldered joints with good conduction are desirable.


A reddish metal that is very thermally and electrically conductive and corrosion resistant. Copper is often used in soldering alloys.


A chemical solid, liquid, or gas capable of irreparably harming living tissue or damaging material on contact. Corrosive residue is left on metals by some soldering fluxes.


The process of removing solder from a defective joint in order to redo the joint. Desoldering may be necessary to correct a bad seal on a joint or a defect that causes improper functioning of a component.

desoldering pump

A device that pulls liquid solder away from the surface of a workpiece. Desoldering pumps can remove substantial amounts of solder.

desoldering tool

A type of soldering iron that contains a hollow tip that can melt solder and is connected to a pump for extracting solder. Desoldering tools combine a soldering iron with a desoldering pump and enable quick removal of solder.

electrical conductivity

The ability to effectively transmit an electric current with low resistance. Good electrical conductivity is often a desired property of a soldered joint.

electronics fabrication

The designing, testing, manufacturing, and distributing of electronic components and assemblies. Electronics fabrication uses soldering for joining delicate components.

electrostatic discharge

ESD. A release of static electricity that occurs when two charged objects come into contact. Electrostatic discharge is a major concern when working with electronics as it can harm equipment and technicians.


Designed to decrease operator discomfort or fatigue and increase productivity. Ergonomic concerns include force, posture, and repetition.

filler metal

A type of metal added to a joint during a fusing process like soldering, brazing, or welding. Filler metals for soldering are called solders.


A substance that chemically cleans base metals to ensure proper and strong joining in soldering, brazing, and welding. Flux helps solder flow more evenly and freely.

flux pens

A flux application tool that is shaped like a marker pen and dispenses controlled amounts of flux onto metal surfaces. Flux pens can be used to supplement or replace flux in solder.

fume extractor

A fan or vent that diverts toxic fumes away from the soldering work area. Fume extractors are the most common type of exhaust system used in soldering.

hand soldering

The process of soldering manually using a soldering iron or soldering gun. Hand soldering is used for repair work and sensitive applications.


A soft, silvery-white metal that resembles tin in appearance. Indium has a low melting point and can be used as a replacement for lead in lead-free solder.

inorganic flux

A flux made from stronger acids that contain compounds of hydrogen with non-metals. Inorganic fluxes are the most active of all the fluxes.


The point at which two pieces of material are joined together. Joints that are soldered are formed using solder.

laser soldering

An automated soldering process that uses a laser to precisely melt solder and form joints. Laser soldering is primarily used for PCBs with heat-sensitive components and can be used for both through-hole components and surface mount devices.


A soft, heavy, toxic, and malleable metal. Lead was often used in solder but is being phased out because of its harmful health and environmental effects.


An electrically conductive component such as a wire or metal pad that connects two areas electrically. Leads in through-hole components are wires that pass through a PCB, and leads in surface mount devices are metal pads.

mechanical fastening

The joining of materials using objects such as nails, rivets, bolts, and screws. Mechanical fastening produces joints with a high degree of strength.

melting point

The temperature at which a material changes from a solid to a liquid. Melting points change based on the composition of the solder.

melting points

The temperature at which a material changes from a solid to a liquid. Melting point will change based on the composition of the solder.


A silvery-white metal with a golden tinge that is hard and ductile. Nickel can be used as a replacement for lead in lead-free solder.

no-clean flux

A flux made with either natural rosin or synthetic resins. No-clean flux is similar to rosin flux, but it contains lower amounts of natural rosins.

organic flux

A flux made from weaker acids that contain carbon. Organic flux is more active than rosin flux.


The process in which a material chemically reacts with oxygen. Oxidation causes rust and tarnish to form on metal surfaces and prevents solder from bonding.


Printed circuit board. An object that mechanically supports and electrically connects electronic components through conductive pathways, or traces, etched onto copper sheets laminated with a non-conductive surface. PCBs require soldering for joining electrical components to the board.

personal protective equipment

PPE. Any clothing or device worn to minimize exposure to hazards and prevent injury. Personal protective equipment for soldering should include safety glasses and flame-resistant clothing.


A material that has a long chain of large, linked molecules. Polymers are mixed with copper to increase electrical conductivity for producing electronics.

printed circuit boards

PCBs. An object that mechanically supports and electrically connects electronic components through conductive pathways, or traces, etched onto copper sheets laminated with a non-conductive surface. Printed circuit boards require soldering for joining electrical components to the board.

protective gloves

A hand covering, which can be made from different materials, that can prevent cuts, burns, and chemical absorption into the skin. Protective gloves are important for soldering as they prevent the absorption of chemicals into the skin and may protect against burns.


Energy that takes the form of waves or particles. Radiation is used in reflow soldering.

reflow soldering

An automated soldering process in which PCBs are passed through an oven on a conveyer belt in order to secure components to the board. Reflow soldering is commonly used for securing surface mount devices to PCBs.

rosin flux

A flux made of rosin, which is a substance derived from the sap of pine trees. Rosin fluxes leave little to no residue.

safety glasses

Protective eyewear, usually made of thick plastic, that shields the eyes from flying debris and other potentially hazardous irritants. Safety glasses should always be worn while soldering.


A chemical compound with a crystalline structure. Salts are one of the active ingredients in organic fluxes.

short circuits

An interruption in the intended flow of electricity, particularly when current flows "short" of reaching a device. Short circuits cause excess current flow that can destroy electronic components, cause fires, or electrocute soldering technicians.


A soft metal that has the highest electrical conductivity of all metals. Silver is used in soldering alloys to create strong joints.


An alloy filler metal with a low melting point that is used to join metals. Solder traditionally contained lead, but more companies are opting for lead-free solder because of the environmental and health hazards lead causes.

solder wick

A braid of flux-coated copper designed to absorb liquid solder. Solder wicks are used with soldering irons to remove small amounts of improperly placed solder.


A low-heat metal joining process in which a filler metal is heated to liquid form then cooled to form a joint. Soldering is used for delicate work such as creating jewelry or electronics.

soldering gun

A type of soldering device with a grip like a pistol and a wide work tip. Soldering guns are not precise, causing them to be used for more heavy-duty tasks.

soldering iron

A tool used to transfer heat to a metal surface and melt solder, which forms a joint. Soldering irons transfer heat through conduction.

soldering iron stand

A non-flammable stand used for resting a hot soldering iron. Soldering iron stands usually also have a place to hold a brass sponge.

soldering stations

A multipurpose soldering device that is equipped with sensors, alerts, and temperature regulation. Soldering stations help when dealing with different types of solder that have various melting points.

soldering technicians

A person who solders. Soldering technicians may use hand soldering for creating jewelry or electronic components.

soldering tips

An interchangeable bit for soldering irons. Soldering tips are specialized for different applications.


A mixture in which a minor component is evenly distributed in a major component. Solutions are usually liquid.

surface mount devices

SMDs. An electrical component that is secured directly to the surface of a printed circuit board. Surface mount devices are more common than through-hole components because they are cheaper and easier to manufacture.


Through-hole components. An electrical component that has leads designed to pass entirely through holes in a circuit board. THCs have strong bonds with the board.

thermal conductivity

A physical property that indicates how well heat energy transfers through materials. Thermal conductivity that is high works well in applications requiring thermal control.

through-hole components

THCs. An electrical component that has leads designed to pass entirely through holes in a circuit board. Through-hole components have strong bonds with the board.


A silvery white metal that is very soft and has poor strength. Tin is used in solder for its low melting point.


The process of applying a trace amount of solder to the tip of a soldering iron. Tinning helps facilitate heat transfer in soldering.

wave soldering

An automated soldering process in which a conveyer belt loaded with PCBs passes over a vat of molten solder. Wave soldering is commonly used for securing through-hole components to PCBs.


The joining of two pieces of metal through the application of heat or pressure. Welding generates high temperatures that melt the base metals to join the workpieces.


The behavior of a liquid when it contacts a solid surface. A good wetting capability is important for soldering because it allows liquids to spread out evenly across a solid surface.


A crystalline growth of tiny hair-like structures in a metal. Whiskers occur in solders that use tin and can cause electrical malfunction.