Bondpad arrays on a PCB allow the installation of unpackaged IC silicon dies directly onto the PCB laminate. They then may or may not be sealed in an encapsulation resin.
Bondpads are electroplated with hard gold and serve as a weld point for a thin gold wire leading to the silicon die.
Soldermask is kept out of the immediate area of the bond pads because registration tolerance is on the same order of magnitude as the size of the bond pads themselves.