Method of making fine-pitch circuit lines

Abstract

A method of making fine-pitch circuit lines includes steps of preparing an insulative substrate, disposing a conductive metal layer on the insulative substrate, disposing on a whole or a part of a top surface of the conductive metal layer a hetero layer having an etching rate smaller than that of the conductive metal layer, forming a patterned mask of circuit lines on the hetero layer, wet etching the hetero layer and the conductive metal layer, and removing the patterned mask and the hetero layer so as to form fin-pitch circuit lines having a high etching factor on the insulative substrate.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates generally to a method of making a printed circuit board (hereinafter referred to as “PCB”), and more specifically to a method of making a PCB having fine-pitch circuit lines thereon.[0003]2. Description of the Related Art[0004]Conventionally, integrated circuit chips or electronic components are mechanically supported by and electrically connected with a PCB or a wiring substrate for a chip package. For electrical connection with the chips or the electronic components, the circuit board or the substrate is provided at the top thereof with circuit lines forming a specific circuit pattern. It is well known that the circuit pattern is mainly made by wet etching. In the known conventional etching methods, the wet etching, which is developed and adopted by manufacturers long time ago, is nowadays still being used extensively because of its economic advantage. Basically, the production of circuit...

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