the.com/circuit board
A city map where electricity is the only commuter, and it never takes a detour.
means A flat board of insulating material that holds electronic components and connects them with printed metal pathways instead of loose wires.
from 'Circuit' traces back to Latin circuitus, 'a going around' (circum, 'around' + ire, 'to go') — originally describing any closed loop a thing travels in. Electrical circuits borrowed that sense in the 1700s-1800s for the closed loop current must complete to flow. 'Board' is just the old Germanic word for a flat slab of wood, later stretched to mean any flat panel. Printed circuit boards themselves are a 20th-century invention — etching the 'wires' as copper traces directly onto a board, replacing tangles of hand-wired connections, so the 'board' is literal and the 'circuit' is the ancient loop, now printed rather than strung.
- copper highways
- traces are literally etched roads for electrons
- color code
- green is just the cheapest solder mask color
- layer count
- modern boards stack up to 20 layers deep
- first one
- invented in 1936, hidden inside a radio