LIBRARYComponent placement.
Placement decides how easy routing is and how well the board works. Connectors at the edges, decoupling caps at the power pin, parts grouped by function, and heat given room.
Placement is where you decide how easy the board is to route and how well it works. Place with intent: connectors at the edges, each chip's decoupling capacitor hard against its power pin, related parts grouped by function, and hot parts given room. Good placement makes routing almost fall out. Bad placement fights you the whole way.
Place the fixed things first
Start with what cannot move: the connectors, mounting holes, and any part whose position is set by the enclosure or the outside world. A USB connector belongs at a board edge because a cable has to reach it. Once the fixed parts anchor the layout, everything else places around them.
Group by function
Keep a circuit's parts together: the power section in one region, the microcontroller and its support in another, any analog or sensing parts in their own quiet corner. Parts that connect on the schematic should sit near each other on the board, because every net you shorten now is a trace you do not fight later.
Decoupling caps touch the pin
A decoupling capacitor only works if it is close. The loop from the capacitor to the chip's power pin and back through ground has inductance, and the longer that loop, the less the capacitor can react to a fast current demand. So the 100 nF cap goes right at the power pin, on the same side, with the shortest possible path, before you place anything less urgent.
Keep noisy and sensitive apart, and leave room for heat
A switching regulator or a fast digital bus radiates, and a sensitive analog input picks that up, so put distance between them. Give a part that dissipates real power, a regulator or a driver, open space and copper around it so its heat has somewhere to go. And leave lanes between the groups for the traces that will connect them.
Let the ratsnest guide you
The ratsnest draws a straight line for every unrouted connection. When a placement makes those lines short and untangled, routing is easy. When the lines cross into a knot, the placement is telling you to move something. Nudge parts until the ratsnest looks calm, and only then start laying copper.
▸Deep dive· Return-path-aware placement
Placement sets more than trace length; it sets where return current flows. A signal's return travels in the ground plane directly under the trace, so a part placed such that its signal has to hop over a gap or a board cutout forces that return on a long detour, and that loop radiates. Placing related parts over the same continuous stretch of ground plane keeps every return short and tight, the same low-inductance idea that makes a plane beat a trace in the first place (All About Circuits).
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One Thousand Drones engineering team · verified 2026-07
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