A printed circuit board (PCB) assembly is provided. The PCB assembly comprises a printed wiring board (PWB) and one or more electrical components mounted thereon. The PWB comprises a plurality of layers including conductive layers and insulative layers, where one or more of the insulative layers is a prepreg layer that is halogen-free; one or more slotted portions on a surface of the PWB, which are indented into the PWB; and one or more pads disposed on the surface of the PWB, which are paired with the one or more slotted portions. Each of the one or more electrical components is mounted on the surface of the PWB through a pair of a slotted portion and a pad.