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US 12,575,036 B2Granted
Method of forming high aspect ratio plated through holes
AssigneeSanmina Corporation
InventorsDouglas Ward Thomas, Shinichi Iketani, Dale Kersten
Life of this patent
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Abstract
The present invention relates to printed circuit boards (PCBs), and more particularly, to methods of forming high aspect ratio through holes and high precision stub removal in a printed circuit board (PCB). The high precision stub removal processes may be utilized in removing long stubs and short stubs. In the methods, multiple holes of varying diameter and depth are drilled from an upper and/or lower surface of the printed circuit board utilizing drills of different diameters.
Claims5
A method for forming a plated through hole in a printed circuit board, comprising:
- drilling a first hole having a first diameter from a lower surface of the printed circuit board;
- drilling a second hole having a second diameter through an upper surface of the printed circuit board to the first hole of the printed circuit board, the upper surface opposite the lower surface;
- plating the first hole and the second hole with a conductive material;
- and
- drilling a third hole having a third diameter through the first hole and the second hole, thereby forming a continuous plated through hole having uninterrupted metal plating from the upper surface to the lower surface of the printed circuit board;
- wherein the second hole is drilled a predetermined depth;
- and wherein the predetermined depth is shorter than half a vertical distance of the printed circuit board;
- and
- wherein the second diameter is larger than the first diameter;
- and wherein the third diameter is smaller than the second diameter and larger than the first diameter.
7 more elements
Dependencies are inferred from the claim text.