Printed circuit board
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Solution Overview
Problem
The challenge of delamination between micropatterns and organic insulating layers during the etching of seed metal layers for plating in printed circuit boards, particularly in high-density wiring applications, is exacerbated by the thickening of the seed layer, which increases etching time and undermines structural integrity.
Innovation Solution
A multi-layer seed metal structure is employed, where one metal layer is thicker than the others, utilizing metals with high electrical conductivity, such as aluminum, iridium, molybdenum, tungsten, cobalt, nickel, or ruthenium, to stabilize the plating process and prevent delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seed layer is made thicker to enable stable plating, then plating stability is improved, but etching time increases and delamination occurs
Solution Approach 1:
The seed layer is divided into multiple sub-layers with different thicknesses and materials. The first seed layer has greater thickness for plating stability, while the second seed layer has lesser thickness to reduce etching time and prevent undercut. This segmentation allows each layer to fulfill different functional requirements simultaneously.
Solution Approach 2:
The patent uses composite seed layer structure combining different metal materials (e.g., copper and tungsten, or copper and molybdenum) with different properties. The first seed layer uses copper for high conductivity and plating stability, while the second seed layer uses tungsten or molybdenum for etching resistance and structural support, creating a composite structure that balances plating stability and etching time.
2Reliability
If the seed layer is made thicker to enable stable plating, then plating stability is improved, but delamination occurs between micropattern and organic insulating layer
Solution Approach 1:
The seed layer is segmented into first and second seed layers with different thicknesses. The first seed layer (thicker) provides plating stability, while the second seed layer (thinner) is positioned to prevent undercut and delamination. This segmentation allows the structure to maintain integrity while achieving stable plating.
Solution Approach 2:
The patent employs composite materials in the seed layer structure, combining copper (for plating stability) with tungsten or molybdenum (for structural support and undercut prevention). This composite structure maintains structural integrity while enabling stable plating without delamination.
3Productivity
If high wiring density is implemented, then circuit functionality is improved, but delamination risk increases due to thicker seed layers
Solution Approach 1:
The seed layer is segmented into multiple layers with optimized thicknesses. The first seed layer enables high wiring density through stable plating, while the second seed layer prevents undercut and delamination. This segmentation allows high wiring density to be achieved without compromising structural integrity.
Solution Approach 2:
The patent uses composite materials (copper combined with tungsten or molybdenum) in the seed layer structure to enable high wiring density while preventing delamination. The copper layer provides plating stability for high-density wiring, while the tungsten/molybdenum layer prevents undercut and maintains structural integrity.
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 multi-layer seed metal structure effectively reduces etching time, prevents undercut and delamination, and ensures smooth plating, maintaining the integrity of micropatterns in high-density circuit boards.
Implementation Method 1
the first metal may be one selected from the group consisting of aluminum (Al), iridium (Ir), molybdenum (Mo), tungsten (W), cobalt (Co), nickel (Ni), and ruthenium (Ru)
Implementation Method 2
patterning may be basically possible through a wet etching process
Data Source
AI summary
A printed circuit board including: a conductive pattern including a seed metal layer and a pattern metal layer disposed on the seed metal layer, and the seed metal layer includes a first metal layer including a first metal, and a second metal layer disposed on the first metal layer and connected to the pattern metal layer and including a second metal, the first metal layer has a thickness thicker than the second metal layer, and the first metal is one selected from the group consisting of aluminum (Al), iridium (Ir), molybdenum (Mo), tungsten (W), cobalt (Co), nickel (Ni), and ruthenium (Ru).