Methods of forming high aspect ratio plated through holes and high precision stub removal in a printed circuit board
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.
Claims20
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 second hole drilled a predetermined depth which is shorter than half the vertical distance of the PCB, and the upper surface opposite the lower surface;
- plating the first hole and the second hole with a conductive material;
- drilling a third hole having a third diameter through the first hole and the second hole;
- and
- adding copper to any remaining conductive surface by electrolytic plating.
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;
- drilling a third hole having a third diameter through the first hole and the second hole;
- and
- plating the third hole with a conductive material forming a plated through hole;
- wherein the second hole is drilled to a top of the first hole;
- and
- wherein the third diameter is larger than the first diameter and the second diameter.
A method for forming a plated through hole having a high aspect ratio in a printed circuit board, the printed circuit board comprising an upper surface and a lower surface, the method comprising:
- drilling a first hole having a first diameter from the lower surface of the printed circuit board to approximately half the vertical distance of the printed circuit board;
- drilling a second hole having a second diameter from the upper surface of the printed circuit board to an upper end of the first hole;
- drilling a third hole having a third diameter through the first hole and the second hole from the lower surface to the upper surface, wherein the third diameter is larger than both the first diameter and the second diameter;
- and
- plating the third hole with a conductive material forming a plated through hole.
Dependencies are inferred from the claim text.