Standard Copper thickness is 35um which can not meet many power supplies or other high current requirements. Storm Circuit has much experience in heavy copper PCB from 2 OZ to 12 OZ.90% of heavy copper we made is 5-8oz,and few is over 10OZ. Here is a simple board with 5oz copper we made again.
 5OZ board |  5 OZ PCB |
Heavy copper PCB are most used in power supplies,like this board has a transformer on it.