Substrate- This is the base material that gives a PCB its thickness. For most printed circuit boards, this is usually fiberglass or kapton. The substrate, often known as FR4, gives the PCBs the rigidity required to hold several components in place. The thickness and weight of the substrate will vary from one manufacturer to the other.
Solder-starved joint- In soldering, a solder-starved joint is the point of a bond formed by molten solder that did not receive as much solder as required. Solder starved joints can be caused by a wide range of factors including incorrect soldering temperatures, poor contact between the solder and iron tip and use of poor quality solder. A solder-starved joint often develops cracks with time, forms poor bonding of components and is thus generally unreliable as a contact point especially in soldered electrical components.
Solder- Solder is the metal alloy commonly used to join work-pieces that include sheets of metal, wires, plumbing and other elements common in soldering. The alloy is designed to have a melting point that is lower than that of the components it joins. Without this characteristic, the work-pieces would probably be damaged by the solder or even before the solder effectively binds them.
Soldering- This is the process by which solder is heated using an external heat source and melts to flow into joints and make bonds between metals.
Soldering iron- It is in essence a small, often hand-held tool that could be power or gas operated depending on a variety of factors that melts solder from a source of heat to join various elements known as work-pieces. A soldering iron is made of four components, the power cord –for electric soldering irons- , the tip, thermostat control and the grip. There are various types and configurations of soldering irons.