Saturn is UL-Certified for up to 6-oz copper on inner and outer layers and capable of producing both plated and non-plated PCBs with up to 20 oz copper for double-sided and multilayers. Heavy Copper PCB issues include delamination, inner layer alignment, and etching.
Heavy Cu does not have a set definition per IPC. We generally define Heavy Copper PCB as the use of 3 ounce copper or higher in inner and/or outer layers of a printed circuit or power distribution board.
Heavy copper can be used for a variety of purposes to include high power distribution heat dissipation, planar transformers, and power convertors. New industries such as EV and PV utilize heavy copper for its high current-carrying capabilities while BMS uses it in conjunction with Flex PCB.