Lo más seguro es que sean fiduciales. Son unos puntos que emplean las máquinas de montaje de componentes como referencia a la hora de colocar los integrados, resistencias, condensadores y demás.
Sacado de la wikipedia
In printed circuit board (PCB) design, fiducial marks, also known as circuit pattern recognition marks, allow automated assembly equipment to accurately locate and place parts on boards. These devices locate the circuit pattern by providing common measurable points. They are usually made by leaving a circular area of the board bare from solder-stop coating (similar to clearcoat), in which a filled copper circle is placed. This center metallic disc can be solder-coated, gold-plated or otherwise treated.
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