Multi-Layer Circuit Board Vias Using Plated Metal Pillars
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Solution Overview
Problem
Existing methods for manufacturing multi-layer circuit boards face difficulties in forming extreme fine vias and achieving fine pitch due to limitations in process capability, particularly with laser drilling.
Innovation Solution
A method involving photolithography and electrolytic plating processes is employed to form a metal pillar, followed by chemical mechanical polishing, enabling the creation of extreme fine vias and fine pitch without additional equipment investment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser drilling is used to form vias, then the manufacturing process is simple, but the via diameter cannot be made extremely small and fine pitch cannot be achieved
Solution Approach 1:
The via formation process is divided into multiple sequential steps: forming opening holes through the insulating layer, forming metal pillars through electrolytic plating, and planarizing the surface. This segmentation allows each step to be optimized independently, enabling extreme fine via formation with diameters of 14 μm or less while maintaining process feasibility
Solution Approach 2:
Metal pillars are formed in advance through electrolytic plating before the insulating layer is fully processed. This preliminary action establishes the via structure early in the manufacturing process, allowing subsequent steps to build upon this foundation and achieve the desired fine pitch and via dimensions
2Manufacturing precision
If laser drilling is used for via formation, then equipment requirements are minimal, but fine pitch (30 μm to 50 μm) cannot be achieved
Solution Approach 1:
The mechanical laser drilling process is replaced with a chemical-electrical process combining photolithography, electrolytic plating, and chemical mechanical polishing. This substitution enables precise control of via dimensions and pitch through chemical reactions and electrochemical deposition, achieving 30 μm to 50 μm pitch that is inaccessible to laser drilling
Solution Approach 2:
The manufacturing approach changes from direct mechanical removal (laser drilling) to controlled material deposition (electrolytic plating) followed by controlled removal (chemical mechanical polishing). This parameter change in the formation mechanism allows precise control of via diameter and spacing, achieving the required fine pitch through controlled electrochemical reactions rather than mechanical constraints
3Manufacturing precision
If traditional via formation methods are used, then the process is well-established, but extreme fine vias (14 μm diameter) cannot be formed
Solution Approach 1:
The electrolytic plating process continuously deposits metal to form pillars of precise dimensions, and the chemical mechanical polishing continuously planarizes the surface. These continuous processes eliminate the need for multiple discrete drilling and re-drilling operations, achieving extreme fine via diameters of 14 μm while maintaining efficient production throughput
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
This approach allows for the production of multi-layer circuit boards with vias as small as 14 μm in diameter and a center-to-center spacing of 30 μm to 50 μm, overcoming the limitations of traditional laser drilling.
Implementation Method 1
forming a metal pillar by plating the first opening by using an electrolytic plating method
Implementation Method 2
evenly polishing the metal pillar and the insulating layer
Data Source
AI summary
A method for manufacturing a multi-layer circuit board including an extreme fine that may include: providing a board having one surface on at least a part of which an upper conductive layer is formed and the other surface on at least a part of which a lower conductive layer is formed; forming a lower metal layer on the other surface of the board; forming a first resist layer on the one surface of the board through a photolithography process, and forming a first opening on the first resist layer; forming a metal pillar by plating the first opening by using an electrolytic plating method; removing the first resist layer; forming an insulating layer on a location from which the first resist layer is removed; and evenly polishing the metal pillar and the insulating layer.