In a method of injecting an electrically conductive epoxy into blind vias during drilling or shortly thereafter in order to avoid oxidation of the copper or other metal of the imbedded layer, a machine tool is provided with at least one controllable spindle and at least one injection device. Alternatively, two machine tools, one with at least one controllable spindle and one with at least one injection device, may be provided. A printed circuit board mounted on the machine tool table for drilling is registered in the usual way for the particular machine tool. The machine tool part program then drills a particular pattern for the circuit board for mounting of circuit board components. All of the blind vias as well as through hole vias are drilled at one time by the machine tool by the tools mounted in the spindle or by laser drilling systems, but may also be drilled and filled in any sequence. The drilling operation is followed by the epoxy injecting operation in which a controlled operating device, comprising a reservoir, a pumping mechanism, a hollow needle through which the conductive epoxy flows to the bottom of the hole, a control mechanism, and sensors detect various mechanism operations and when hole fill is completed.