US Patent No. 10,512,174


Patent No. 10,512,174
Issue Date December 17, 2019
Title Method Of Filling Through-holes To Reduce Voids And Other Defects
Inventorship Nagarajan Jayaraju, Framingham, MA (US)
Leon Barstad, Raynham, MA (US)
Assignee Rohm and Haas Electronic Materials LLC, Marlborough, MA (US)

Claim of US Patent No. 10,512,174

1. A method comprising:a) providing a printed circuit board with a plurality of through-holes comprising a layer of electroless copper, copper flash or combinations thereof on a surface of the printed circuit board and walls of the plurality of through-holes, wherein the through-holes have diameters of 75-125 ?m and the printed circuit board is 100 ?m thick or greater;
b) immersing the printed circuit board in a copper electroplating bath comprising an anode; and
c) filling the through-holes with copper by a direct current cycle consisting of applying a current density for a first predetermined period of time followed by applying a lower current density for a second predetermined period of time, wherein the current density for the first predetermined period of time is of a shorter time period than the predetermined time period of the lower current density without repeating the direct current cycle.