PCB Substrate Conductive Ink Filling Openings
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Solution Overview
Problem
Conventional printed circuit board substrates with thin copper foil layers formed by sputtering cannot fill openings through the base film, limiting component mounting area due to insufficient thickness of the first conductive layers.
Innovation Solution
A substrate with a base film having openings filled with a first conductive layer formed by applying and heat-treating a conductive ink containing metal particles, followed by a second conductive layer formed through plating, ensuring dense conductor filling and high conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thin copper layers are formed by sputtering, then the substrate achieves high-density printed circuits with reduced conductive layer thickness, but the copper foil layers cannot fill openings through the base film, limiting component mounting area
Solution Approach 1:
The invention changes the formation method parameter from sputtering to screen printing with conductive paste, and changes the thickness parameter from thin (0.3μm) to thick (5μm or more), enabling the conductive layer to fill openings while maintaining high-density circuit capabilities
Solution Approach 2:
The invention adds a vertical dimension by forming conductive layers that extend through the opening depth, transforming the conductive path from surface-only to three-dimensional, thereby enabling both high-density circuits and adequate component mounting area
2Productivity
If thin copper layers of about 0.3 μm are formed by sputtering, then the substrate meets high-density requirements, but openings cannot be filled and lands for mounting components cannot be formed
Solution Approach 1:
The invention changes the thickness parameter from 0.3μm to 5μm or more, and changes the material form from pure copper foil to conductive paste with filler particles, enabling reliable opening filling while maintaining high-density circuit productivity
Solution Approach 2:
The invention uses composite conductive paste containing conductive fillers (metal powder or flake) in a binder resin, combining the advantages of thick conductive paths for opening filling with the ability to form precise high-density circuit patterns
3Area of stationary object
If conductive paste is applied by screen printing, then openings can be filled with thick conductive layers, but the process complexity increases compared to sputtering
Solution Approach 1:
The invention replaces the physical vapor deposition mechanism of sputtering with a mechanical screen printing process, using paste application and thermal curing instead of plasma and atomic deposition, thereby enabling opening filling while maintaining process simplicity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach allows for dense filling of openings with conductors, providing high conductivity and enabling the formation of a printed circuit board with increased component mounting area and improved adhesion strength between the conductive layer and the base film.
Implementation Method 1
a first conductive layer that is formed on both surfaces of the base film by applying and heat-treating a conductive ink containing metal particles
Implementation Method 2
performing heating at 150° C. or more and 500° C. or less in an atmosphere having an oxygen concentration of 1 ppm or more and 10,000 ppm or less to form a first conductive layer
Implementation Method 3
a second conductive layer formed, by plating, on at least one of surfaces of the first conductive layer
Data Source
AI summary
A substrate for a printed circuit board according to the present invention includes a base film having an insulating property and including at least one opening; a first conductive layer that is formed on both surfaces of the base film by applying and heat-treating a conductive ink containing metal particles, and that fills the at least one opening; and a second conductive layer formed, by plating, on at least one of surfaces of the first conductive layer. The metal particles preferably have a mean particle size of 1 nm or more and 500 nm or less.