The invention discloses a double-surface pressing connecting through hole structure of a printed-circuit board and a
machining method of the double-surface pressing connecting through hole structure of the printed-circuit board. The
machining method comprises the following steps that a
small hole A is drilled in the upper surface of a substrate in a depth-
control mode; a pressing connecting hole B is drilled in the same position of the
small hole A; the substrate is overturned; a
small hole C is drilled in the surface opposite to the small hole A in a depth-
control mode and is communicated with the small hole A; a pressing connecting hole D is drilled in the position of the small hole C; electroless
copper plating,
copper electroplating and
tinning are carried out; a hole E is drilled in the position of the small hole A in a depth-
control mode; the substrate is overturned; a hole F is drilled in the position of the small hole C in a depth-control mode;
alkaline etching and
tin stripping are carried out; part of a
copper layer at each pressing connecting hole is thickened in a plating mode until the design requirement of a finished product is met, and finally the double-surface pressing connecting through hole structure is obtained. The double-surface pressing connecting through hole structure of the printed-circuit board and the
machining method of the double-surface pressing connecting through hole structure of the printed-circuit board completely eliminate the stray
capacitance among pressing connecting elements, facilitates the integrality of
signal transmission and improves wire distribution density; the process is reasonable, the difficulty that plating
layers of the middle small holes are eliminated in a drilling mode is largely lowered, and the
diameter of the pressing connecting holes is made to be the smallest; the completeness of the plating
layers on the walls of the pressing connecting holes is guaranteed, and the non-metallic middle small holes are achieved;
copper wire defects in the holes are avoided.