PCB Design Basics: Stackup, Trace Width, Decoupling and Ground
Essential PCB design rules for hardware engineers: layer stackup, current-carrying trace width, decoupling placement, grounding and return paths.
Stackup, current and traces
Plan a continuous reference plane and choose a stackup that controls impedance for high-speed signals. Size power traces for current and temperature rise using IPC-2152, and use copper pours for heat dissipation.
Keep high-current loops short and wide, and match differential-pair length and spacing for USB, Ethernet and other serial links.
Decoupling and grounding
Place each IC decoupling capacitor as close to the supply pin as possible with the smallest loop, connecting directly to the ground plane. Use bulk plus ceramic combinations.
Avoid slots in return planes; route return current under the signal path. Split analog and digital grounds carefully and join at a single reference point near the converter.
Frequently Asked Questions
How close should decoupling capacitors be?
Place the smallest ceramic capacitor closest to the supply pin (millimeters away) to minimize the high-frequency loop inductance.
How wide should a power trace be?
Width depends on current, copper weight and allowed temperature rise; size it with IPC-2152 rather than guessing.