The printed circuit board (PCB) is usually on a glass epoxy substrate bonded to a layer of copper, The copper thickness generally includes 18μm,35μm,55μm and 70μm and the most common copper thickness is 35μm. Not only 35～50μm of copper thickness used by domestic, also including 10μm,18μm , 70μm and etc.
As a conductor of PCB, copper is a kind of Negative electrolytic material and a thin layer,continuous metal foil under the basal layer of printed circuit board. Copper is easy to be bonded to insulating layer, to receive a printed protective layer and to form circuit pattern after corrosion.Composite copper thickness is 35μm among the l～3mm thickness of base panel; less than 1mm with 18μm thickness and above 5mm with 55μm thickness.
The most common unit of measure for the copper thickness on a PCBA is ounces(OZ). In the PCB industry, 1OZ means that 1OZ of copper is pressed flat and spread evenly over a one square foot area. Per unit area weight is used to present the average thickness of copper, Other converted unit of measure is as following: