PCB design glossary
Autorouter
An EDA tool that lays down copper traces on a PCB automatically, based on the schematic netlist and a set of design rules.
An autorouter takes the connections defined in a schematic (the netlist) and figures out where to put copper on the PCB so every net is connected. Modern autorouters respect design rules — minimum trace width, clearance, via size — and try to minimize total trace length, layer changes, and crosstalk.
Traditional autorouters rely on greedy shortest-path search with rip-up-and-retry. PCBEditor's router routes every layer, gives the same board for the same netlist and rules, checks every result against the design rules and names any net it could not finish.
How autorouters work
Most autorouters treat the board as a grid or a set of shapes and search for a path for each connection, net by net. When a later net is blocked, the router rips up earlier routes and tries again in a different order. That loop, called rip-up and reroute, is what lets a router finish a dense board instead of stalling on the first conflict.
- Maze (grid) routers search cell by cell, like Lee's algorithm. They are thorough but slow on fine grids.
- Shape-based routers work on the real copper geometry, so they handle odd pad shapes and fine pitch better.
- Topological routers decide the order in which nets pass each other first, then fix exact geometry afterwards.
- Push-and-shove routers, common as interactive tools, move existing traces aside to make room for a new one.
Where autorouters struggle
The usual workflow is to place carefully, route critical nets (power, clocks, differential pairs) by hand, then let the autorouter finish the rest, and always run DRC afterwards.
- Intent they cannot read: which nets are sensitive, which must stay short, where the return current should flow.
- Dense fine-pitch parts (QFN, BGA) whose pins need an escape pattern before routing can start.
- High-speed nets that need matched length, controlled impedance or a solid reference plane underneath.
- Poor placement. No router fixes a layout where connected parts sit on opposite corners.
Autorouting in PCBEditor
PCBEditor routes every layer of a generated or imported board, checks every result against the design rules and names any net it could not finish. The same netlist and rules give the same board.
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PCBEditor's router is repeatable: the same netlist and rules always give the same board, and every run finishes with a design-rule report instead of a guess.
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