What is stack up in PCB?

It is the composite of all the layers of artwork for the circuit layers and photo masks and screens.Before designing a multilayer PCB circuit board, the designer needs to first determine the circuit board structure to be used according to the circuit size, circuit board size, and electromagnetic compatibility (EMC) requirements, that is, the decision to use 4 layers, 6 layers, or more layers of circuit boards. After the number of layers is determined, the placement of the internal electrical layers and how to distribute different signals on these layers are determined.
A Stackup is the arrangement of copper layers and insulating layers that combines to make up a PCB prior to the board layout design. A stackup helps in getting more circuitry on a single board through various PCB layers. It can help in minimizing the circuit’s vulnerability to noise, minimize radiation, and reducing impedance and crosstalk concerns on high speed layouts.
A typical stack up for a 6 layer board may be :
Top Silkscreen layer 9
Top Soldermask layer 7
Layer 1 copper signals
Dielectric
Layer 2 copper ground plane
Dielectric
Layer 3 copper signals
Dielectric
Layer 4 copper signals
Dielectric
Layer 5 copper ground plane
Dielectric
Layer 6 copper signals
Layer 8 Bottom Soldermask
Layer 10 bottom Silkscreen

To know more:
What is the ideal RF( Radio frequency )PCB stack up?
Introduction for Formal PCB stackups by fabricators
Go to the PCB knowledge Page
Go to the PCB design resources page
Back to the technology data