Sunday, September 14, 2008

PCB Components: Copper Planes

Copper planes are typically found when power planes and ground planes are utilized. Planes make an excellent high frequency capacitor and can often be utilized for high frequency bypassing in complement with traditional capacitors.

The use of a solid ground plane is generally preferred over a grid plane. A solid plane minimizes inductance to the absolute minimum which is a desirable trait for high speed signals – which includes both Analog and Digital signals. But, as will be discussed later, this plane can cause
capacitance problems to sensitive nodes of the circuit. Be aware of all attributes of the circuit and do not blindly use planes everywhere.

A side benefit of a solid plane is it becomes a very good thermal conductor and can act as a heat sink to keep thermal levels of all devices minimized. But on the flip side, temperature sensitive components may not want to have the ground plane nearby due to this heat spreading.

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