Method of making multilayered printed circuit board with filled conductive holes
View Patent ↗A method of making a printed circuit board in which conductive thru-holes are formed within two dielectric layers of the board's structure so as to connect designated conductive layers. One hole connects two adjacent layers and the other connects two adjacent layers, including one of the conductive layers connected by the other hole. It is also possible to connect all three conductive layers using one or more holes. The resulting holes may be filled, e.g., with metal plating, or conductive or non-conductive paste. In the case of the latter, it is also possible to provide a top covering conductive layer over the paste, e.g., to serve as a pad or the like on the board's external surface.
1. A method of making a multilayered printed circuit board, said method comprising:
providing a first dielectric layer having first and second opposing sides;
forming a first conductive layer on said first opposing side of said first dielectric layer;
forming a second conductive layer on said second opposing side of said first dielectric layer, said second conductive layer including at least one opening therein;
forming a second dielectric layer having first and second opposing sides on said second conductive layer on said second opposing side of said first dielectric layer, said first opposing side of said second dielectric layer being in contact with at least part of said second conductive layer including over said at least one opening therein;
forming first and second holes within said second dielectric layer using a laser, said first hole extending down to only said second conductive layer and a part of said second hole extending through said at least one opening in said second conductive layer and down to said first conductive layer, said first and second holes, including said part of said second hole extending through said at least one opening in said second conductive layer and down to said first conductive layer, each being of tapered configuration and having surfaces;
forming a third conductive layer on said second opposing side of said second dielectric layer;
forming a conductive coating on said surfaces of said first and second holes so as to electrically couple said first and second conductive layers with said conductive coating on said second hole and said second and third conductive layers with said conductive coating on said first hole;
plating said first and second holes having said conductive coatings thereon with plating material to fill said first and second holes, including said part of said second hole extending through said at least one opening in said second conductive layer and down to said first conductive layer; and
forming a substantially solid upper surface on said conductive material within each of said first and second holes.
2. The method of claim 1 wherein said conductive coating on said second hole also electrically couples said second conductive layer and said third conductive layer.
3. The method of claim 1 wherein said first, second and third conductive layers are formed using photolithographic processing.
4. The method of claim 1 wherein said conductive coatings are formed on said surfaces of each of said holes using a plating process.
5. The method of claim 1 wherein said second dielectric layer is formed on said second conductive layer using a laminating process.
6. A method of making a multilayered printed circuit board, said method comprising:
providing a first dielectric layer having first and second opposing sides;
forming a first conductive layer on said first opposing side of said first dielectric layer;
forming a second conductive layer on said second opposing side of said first dielectric layer, said second conductive layer including at least one opening therein;
forming a second dielectric layer having first and second opposing sides on said second conductive layer on said second opposing side of said first dielectric layer, said first opposing side of said second dielectric layer being in contact with at least part of said second conductive layer including over said at least one opening therein;
forming first and second holes within said second dielectric layer using a laser, said first hole extending down to only said second conductive layer and a part of said second hole extending through said at least one opening in said second conductive layer and down to said first conductive layer, said first and second holes, including said part of said second hole extending through said at least one opening in said second conductive layer and down to said first conductive layer, each being of tapered configuration and having surfaces;
forming a third conductive layer on said second opposing side of said second dielectric layer;
forming a conductive coating on said surfaces of said first and second holes so as to electrically couple said first and second conductive layers with said conductive coating on said second hole and said second and third conductive layers with said conductive coating on said first hole;
filling said first and second holes having said conductive coatings thereon with conductive paste, including said part of said second hole extending through said at least one opening in said second conductive layer and down to said first conductive layer; and
forming a conductive layer over said conductive paste within each of said first and second holes.
7. The method of claim 6 wherein said conductive coating on said second hole also electrically couples said second conductive layer and said third conductive layer.
8. The method of claim 6 wherein said first, second and third conductive layers are formed using photolithographic processing.
9. The method of claim 6 wherein said conductive coatings are formed on said surfaces of each of said holes using a plating process.
10. The method of claim 6 wherein said second dielectric layer is formed on said second conductive layer using a laminating process.