A simple basic question.
Most stack-up calculators show a Thickness for each layer involved but when building a PCB, There is a base copper that is drilled then the base is plated over to make the interconnection. So are the stack-up generators using the base or final copper thicknesses?
I had one company state they start with a base of 1/2 to 1 oz copper and plate 1-2 oz. Which means a final plating of between 1.5 and 3 oz of copper which can have a wild impact on impedances etc!
I have attached a sample stackup for example.
In layer1 the specified thickness of 1.45 mil (1 oz) is referring to the final plated copper thickness. The starting copper thickness of 0.35 mil (0.25 oz) and the plating thickness of 1.1 mil combine to achieve the final thickness of 1.45 mil (1oz).
It’s essential to consider the final plated copper thickness when designing PCB stack-ups because it directly impacts various parameters such as impedance, current carrying capacity, and mechanical strength. The difference between the starting copper thickness and the final plated copper thickness can indeed have significant implications for the electrical performance of the PCB. Therefore, it’s crucial to communicate clearly with your PCB manufacturer regarding your requirements and specifications to ensure the desired performance of your PCB design.
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