Differential Phase Skew Mitigation through Spread Glass Prepreg Selection
Spread glass prepreg selection eliminates differential phase skew by flattening fiber bundles and reducing dielectric constant variations across signal paths.
High-Speed Stackup Architecture
Layer Configuration
Strategic arrangements of signal, ground, power, and isolation planes in a multilayer board optimize electromagnetic compatibility and signal integrity. Developing a high-speed stackup architecture involves selecting dielectric materials and copper weights that meet impedance and loss targets. This process defines the vertical transition paths for vias and the coupling between traces.
It provides the foundation for reliable data transmission at microwave frequencies.
Signal Isolation
Shielding between sensitive signal layers is achieved by placing ground planes in close proximity to the signal paths. A high-speed stackup architecture often utilizes thin dielectric layers to increase capacitive coupling to the reference planes. This reduces crosstalk and electromagnetic interference.
Proper spacing between differential pairs and unrelated signals is calculated during the design phase.
Fabrication Tolerance
Manufacturing a board with multiple high-frequency layers requires precise control over the lamination process. Each layer in a high-speed stackup architecture must be registered with high accuracy to ensure via-to-pad alignment. The resin flow of the prepreg layers determines the final distance between planes.
Slight variations in the pressed thickness can shift the characteristic impedance by several ohms. Fabricators use specialized software to predict these variations and adjust the design files accordingly. Testing with impedance coupons verifies that the finished board meets the electrical requirements.