What is the definition of "solder"?
A fusible metal alloy, with a melting point or melting range below 840°F (450° C), which is melted to join metallic surfaces, especially in the fields of electronics and plumbing, in a process called soldering.

Learn more about solder in the class What Is Soldering? 110 below.

Soldering Training

Class Information
Soldering Training Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:What Is Soldering? 110
Description:This class provides an overview of the basic tools and components used for soldering, briefly explores the importance of soldering to the electronics industry, and covers basic procedures for soldering preparation, safety, and cleanup.
Prerequisites: none
Number of Lessons:13
Language:English, Spanish
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Class Outline
  • Objectives
  • What Is Soldering?
  • What Is Solder?
  • Advantages of Soldering
  • Disadvantages of Soldering
  • What Is Flux?
  • Types of Flux
  • Manual Soldering vs. Automated Soldering
  • Electronics Fabrication
  • The Soldering Process
  • Soldering Tools and Accessories
  • Basic Safety Precautions
  • Summary
Class Objectives
  • Define soldering.
  • Define solder.
  • List the advantages of soldering.
  • List the disadvantages of soldering.
  • Define flux.
  • List the common types of flux.
  • Compare and contrast manual soldering with machine soldering.
  • Provide general background on soldering in the electronics industry.
  • Explain what happens during the soldering process.
  • List the tools and accessories used in soldering.
  • Discuss basic soldering preparation and safety procedures.

Class Vocabulary

Vocabulary TermDefinition
activator A substance that initiates or accelerates a chemical reaction without being affected itself.
activity The measure of flux cleaning strength. The more active the flux, the more effectively it cleans.
adhesive bonding The joining of two or more materials through the use of a nonmetallic material such as liquids, drops, or gels.
alloy A uniform mixture of two or more materials. One of the materials must be a metal.
ammonia A toxic and corrosive compound with a characteristic pungent odor.
antimony A blue-white metal used in a wide variety of alloys, electronics, and rubber.
arcing Overheating that occurs when electricity flows from one surface to another. Electric arcs are dangerous because they can cause electric shock as well as burns and UV radiation.
bismuth A white, brittle metal with a pinkish tinge that is added to steel to improve machinability.
brazing A process in which a filler metal is melted at a temperature above 840° F (450° C), but below the melting point of the base metals to form a joint between two base metals. Brazing differs from welding because only the filler metal is melted.
capillary action The ability of a substance to draw a liquid upwards against the force of gravity. For example, solder clings to a lead wire protruding upward from a PCB hole through capillary action.
clamps Devices used to join, grip, support, or compress mechanical or structural parts.
cold joint A dull, poorly soldered joint that does not provide good conductivity.
conduction The transmission of heat across matter.
conductivity The measure of a material's ability to conduct heat or electric current.
convection The transfer of potential energy, for example heat, by currents within a fluid.
desoldering The removal of solder and components from a circuit for troubleshooting and repair purposes.
electrical assembly An electrical assembly is made from a frame, an electrical connector, and a self-contained part known as a module.
electrically conductive Electrical conductivity refers to an object's ability to transmit an electrical charge.
electronics fabrication The design, test, manufacture, and distribution of electronic components and assemblies.
eutectic point The lowest temperature at which a substance will melt.
flux A substance that facilitates soldering, brazing, and welding by chemically cleaning the metals to be joined.
flux pen A flux application tool, usually shaped like a marker pen, that channels controlled amounts of water-soluble flux onto metal surfaces.
fume extractor A fan or vent that diverts toxic fumes away from the soldering work area.
hand soldering Soldering that is performed manually with a soldering iron.
heat transfer The passage of thermal energy, i.e. energy in the form of heat, from a hot to a cold body.
hydrochloric acid An acidic, highly corrosive chemical compound used in industry.
inorganic Composed of matter other than plant or animal.
joint The point at which two pieces of metal make contact and are bonded together with solder.
lead A soft, heavy, toxic and malleable metal often used in solder.
organic Derived from a living organism.
oxidation A material's chemical reaction with oxygen. Oxidation causes rust and tarnish to form on metal surfaces, and prevents solder from bonding.
PCBs In electronics, printed circuit boards, or PCBs, are used to mechanically support and electrically connect electronic components using conductive pathways, or traces, etched from copper sheets laminated onto a non-conductive surface.
photons Particles of light energy produced by the sun.
radiation A process of emission of energy in the form of waves or particles.
reflow soldering An automated soldering process in which PCBs are run through an oven on a conveyor belt. Heat from the oven causes granules of solder to melt and form a joint.
residue A substance deposited or left behind by a reaction or event.
robot A mechanical device that automatically performs complicated and repetitive taks. Robots often perform work that is too dangerous or strenuous for humans.
rosin-based A rosin-based flux is composed of rosin, a substance derived from the sap of pine trees.
short circuits An interruption in the intended flow of electricity, especially when current flows "short" of reaching a device. A short circuit causes excess current flow.
silver A silvery white metal that has the highest electrical conductivity of all metals. Silver is also fairly expensive.
solder A fusible metal alloy, with a melting point or melting range below 840°F (450° C), which is melted to join metallic surfaces, especially in the fields of electronics and plumbing, in a process called soldering.
soldering A process in which a filler metal is melted at temperatures below 840° (450° C) to form a joint between two base metals. Soldering is often used for delicate projects such as jewelry and electronics.
soldering iron A tool used to transfer heat to a metal surface in order to melt solder and form a joint or circuit. Most soldering irons resemble a large pen.
soldering iron stand A non-flammable stand upon which to set a hot soldering iron.
soldering station An all-in-one combination of soldering accessories: soldering iron, iron stand, cleaning pad, energy source. Some stations include fume extractors as well.
tin A silvery white metal that is very soft and has poor strength. Tin is used in soldering alloys.
tinning The action of applying a trace amount of solder to the tip of the soldering iron in order to facilitate the heat transfer process.
toxic Poisonous or harmful. Lead is considered to be highly toxic.
vapor-phase soldering An automated soldering process in which PCBs are put in a chamber with a volatile liquid chemical at the bottom. The chemical is heated to its boiling point to form steam, and the steam heats the solder paste at the bottom of the board.
water-soluble The ability of a substance to dissolve in water.
wave soldering An automated soldering process in which PCBs are loaded onto a conveyor that passes over a vat of molten solder. As the conveyor belt moves, a wave is created with a pump. The bottom of the board hits the crest of the wave, and the solder sticks through capillary action.
welding The joining of two pieces of metal together through the application of heat.
wetting The behavior of a liquid when the liquid contacts a solid surface. Liquids with poor wetting ability tend to form droplets, while liquids with good wetting ability tend to spread out evenly over the solid surface area.
whiskers A crystalline metallurgical phenomenon whereby metal grows tiny, filiform hairs. The effect is primarily seen on elemental metals but also occurs with alloys.