The rat's nest is the web of straight lines, also called ratlines or air wires, that a layout tool draws between pins the netlist says must connect but that have no copper yet. Designers use it to judge placement, rotating and moving parts until the lines are short and untangled before routing starts. Leftover rat's nest lines at release mean unrouted nets, which the DRC should catch.
Placement's not done until the rat's nest stops looking like spaghetti, rotate that connector 180 and look again.
Also heard as
- ratsnest
- ratlines
- air wires
- connection lines
Related terms
Netlist
List of every electrical connection in a design, naming which pins belong to which net.
Fanout
Short connections that bring each pin of a dense part out to a via so it can be routed on other layers.
DRC
Design rule check: automated scan of a layout for spacing, width, drill and connectivity violations.