Real image: CORE3588, rendered by KiCad from our board file
CORE3588 top side, the three ESP32 recovery pads. Our fab notes order ENIG for this board.
1Test pads for the ESP32 boot and reset lines: bare pads with no part on them, so the finish shows. The render paints them gold, which is what ENIG pads look like.
How it works
Where it fits
ENIG is the surface finish on CORE3588. The cheaper alternative is HASL. Either way the finish sits only on exposed pads; everything else is under soldermask.