| CPC H05K 3/425 (2013.01) [C25D 3/38 (2013.01); C25D 5/022 (2013.01); C25D 5/18 (2013.01); C25D 5/34 (2013.01); C25D 5/48 (2013.01); C25D 7/00 (2013.01); H01L 21/4857 (2013.01); H01L 21/76877 (2013.01); H05K 3/108 (2013.01); H05K 3/423 (2013.01); H05K 3/429 (2013.01); H05K 3/4623 (2013.01); H05K 3/181 (2013.01); H05K 2203/0353 (2013.01); H05K 2203/072 (2013.01); H05K 2203/0723 (2013.01); H05K 2203/1492 (2013.01)] | 13 Claims |

|
1. A method of preparing a high density interconnect printed circuit board (HDI PCB) including microvias filled with copper, the method comprising the steps of:
a2) providing a multi-layer substrate (10) comprising
(i) a stack assembly of an electrically conductive interlayer (14) embedded between two insulating layers (12) having a peripheral surface,
(ii) a microvia (20) extending from the peripheral surface of the insulating layers (12) of the multi-layer substrate (10) and ending on the conductive interlayer (14);
b2) depositing a conductive layer (30) on the peripheral surface of the insulating layers (12) of the multi-layer substrate (10) and on an inner surface of the microvia (20);
c) electrodepositing a copper filling (42) in the microvia (20) and a first copper layer (40) on the conductive layer (30) wherein a thickness of the first copper layer (40) is from 0.1 to 3 μm and wherein the copper filling (42) and the first copper layer (40) form together a planar surface (32);
and, subsequent to step c):
d) forming a patterned masking film (50) on the first copper layer (40);
e) electrodepositing a second copper layer (60) in the area not covered by the patterned masking film (50); and
f) removing the patterned masking film (50).
|