Voltage Distribution
Continuous sheets of copper within a multilayer printed circuit board provide a low-impedance path for DC power. In modern electronics, power planes act as the primary reservoir for current distribution to integrated circuits and other active components. They simplify routing.
A solid copper layer also acts as an electromagnetic shield and provides a stable reference for signal layers.
Thermal Management
Heat dissipation is a secondary function of large copper areas. High-power components transfer thermal energy into the power planes through vias, allowing the heat to spread across the entire board surface. This spreading lowers the operating temperature of individual devices and prevents localized hot spots.
The thickness of the copper determines the current-carrying capacity and the effectiveness of the thermal conduction.
Stackup Design
Layer arrangement affects the capacitance and noise performance of the distribution system. Placing ground and power planes on adjacent layers creates a decoupling capacitor that filters high-frequency noise from the power supply. Small gaps or splits in these power planes allow for multiple voltage levels on a single plane but require careful routing to avoid signal integrity issues.
A balanced stackup prevents the board from warping during the soldering process. When high-speed traces cross a split in the plane, the return path is interrupted and electromagnetic interference increases. Designers must ensure that signals stay over a continuous reference to maintain low noise levels.
