Abstract
This study proposes a technique for manufacturing a printed circuit board (PCB) with fine Cu line width of less than 5 μm. Fabrication of a fine Cu structure on both sides of liquid crystal polymer (LCP) substrates was demonstrated using a combination of (i) structuring with thermal nanoimprint lithography and (ii) Cu plating followed by etching technique. Two Si master molds possessing many linear trenches (1 μm width, 2 μm pitch, and 5 μm depth) on the surface were used. The mold shapes were coinstantaneously transferred to both sides of LCP using an appropriate nanoimprint condition. These formed trenches were filled by electroless and electrolytic Cu plating under suitable plating conditions while restraining excess Cu deposition to about 1 μm on the LCP surface. After eliminating the excess Cu on the surface using etching solutions, we fabricated an isolated linear Cu structure of 1 μm width on both sides of LCP. The fabrication technique for narrow lines of less than 5 μm width for PCB is still not established, but results show that thermal nanoimprinting will be applicable to the manufacture of PCB with about 1 μm line width.
