Hi,
I am trying to understand about PCB layer stack up.
It is a 4 layer PCB, 1oz copper, 1.6mm PCB thickness, FR4 Hi TG, ENIG finish.
The stack up is:
Top solder mask
Top Copper
Prepreg
Inner 1 GND
Core
Inner 2 Power
Prepreg
Bottom.Copper
Bottom solder mask
My question is how to I assign appropriate copper thicknesses for top, inner1/2 and bottom layers? What should the core thickness and prepreg thickness be?
I was going to talk to them, but I wanted to understand from my point of view.
For example 1oz - does that mean top / bottom / inner 1 and inner 2 should all be at 35um? I have seen 18um for the top and bottom, then 35um for inner layers? Not sure why?
My other question is, if the PCB thickness is to be 1.6mm, then should the thickness of each layer totalled together be 1.6mm?
How do I know what the prepreg and core thickness should be?
Hi,
What Klaus shared are almost the right answer. as an experienced PCB technical guy in PCB industry, I would like to offer much more information to your questions.
1. when define 1oz for both inner and outer layer, the copper thickness should be controlled as following:
inner layer 24.9um(min), typical thickness 28-32um.
top and bottom layer 33.4um(min), typical 35-38um.
refer to copper control defined in IPC 6012E ( default IPC class 2)
when PCB house offer the stack-up for approval , the copper thickness for outer layer don't cover plating copper (average 20um) , this is why you could only see 18um for top and bottom layer in stack-up.
regarding the 1.6mm total thickness , if you could share the stack-up your present PCB supplier offered , I can explain and make your clear if the thickness 1.6mm covers all material like solder mask , plating copper, original copper , prepare and core thickness .
I hope above shares could help you out.
Koen.Hu