Heavy Copper Board does not have a certain definition per IPC. According to PCB industry use this name“heavy copper“ to identify a printed circuit board with copper conductors 3 oz – 10 oz for outer and inner layers. And Extreme heavy copper PCB refers to 20 oz to 100 oz printed circuit board.

Heavy copper normally used for a various products but not limited to: high power distribution, heat dissipation, planar transformers, power convertors, etc…