Method for backdrilling via stubs of multilayer printed circuit boards with reduced backdrill diameters

A printed circuit board (PCB) comprising:

• a first substrate, said first substrate including a first and a second surface wherein said surfaces are approximately parallel to each other and wherein a separation distance between said first and said second surface defines a thickness of said first substrate, wherein said first substrate comprises a plurality of layers laminated together to form said first substrate;
• a plurality of vias extending from said first surface, through said first substrate, to said second surface, wherein a length of a first via of said plurality of vias extends from said first surface to said second surface, wherein said first via comprises a first portion along said length and a second portion along said length, wherein a diameter of said second portion is less than 3 mils larger than a diameter of said first portion;
• a first plating layer covering an entirety of said first portion and at least partially covering said second portion;
• and
• a second plating layer covering an entirety of said first plating layer covering an entirety of said first portion, wherein the chemical composition of said first plating layer is different than the chemical composition of said second plating layer, wherein said second portion is free of said second plating layer.