Printed Wiring Board Processes
The additive process is to form a conductor path by adding copper to exposed substrate at the desired location. By screening the conductive paste, copper is plated on the predefined conductor track or the insulated conductor is placed on the substrate.
Subtractive process is of the PWB (printed wiring board) type in which unnecessary portions of the copper foil on the base substrate are etched away leaving behind the required conductor pattern.
The organic substrate is composed of a paper layer soaked with phenol resin or woven or nonwoven glass material drenched with an epoxy resin or a cyanate ester. The use of such substrates depends on physical features required for the use of printed circuit boards, such as operating temperature, voltage, current, frequency, or mechanical properties.
The non-organic substrate contains metal and ceramic materials like aluminum, insulated metal substrate IMS, soft iron, Kapton, Pyralux, FR-2, FR-4 used for flexible PCBs. The use of these substrates is determined by the need for heat dissipation and thermal properties.