A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate.
PCB Substrates are specialized materials that do not conduct electric current. They act as laminated insulator between the circuitry.
Following are the common types
1. FR-2(Fire resistant 2)
It is a low grade substrate and is made up of impregnated paper also called phenolic. It is easy to machine over as compared to a fibre glass substrate. this type of substrate is found in inexpensive electronic products.
2. FR-4(Fire resistant 4)
It is made up of woven fibre glass material and is impregnated with flame resistant material. this substrate is more stronger than FR-2 .It is usually found in higher grade electronics.
These substrate are composed of material having low dielectric value and are used in applications where high power radio frequencies are involved.
4. FLEX SUBSTRATE
Thin and flexible plastics or films are used to make them. These are used at places where bending is required or repetitive bending is required or their is constraint of space.
As he name suggests these are made up of metals and have non conductive coating,these are used in high power circuits and act as heat sink in addition to providing path for flow of current. Usually found in high wattage LED base.