Wiring Substrate Inverted Trapezoidal Conductor Shape
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Solution Overview
Problem
Conventional wiring substrates using copper chloride etching solutions struggle to achieve high-density wiring patterns due to the inability to reduce inter-wiring distances effectively, as the width of the upper surface of the conductor layer is typically smaller than the lower surface, limiting the density of wiring patterns.
Innovation Solution
A method involving the formation of a copper conductor layer on a substrate with an upper surface width equal to or larger than the lower surface width, and a lower surface width greater than the middle portion width, utilizing a copper chloride etching solution with an etching inhibitor to control the etching rate and achieve the desired shape, allowing for reduced inter-wiring distances and higher density patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional copper chloride etching solution is used to form a conductor layer, then the etching process can be performed, but the upper surface width becomes smaller than the lower surface width, limiting wiring density
Solution Approach 1:
The etching solution is designed with different components that act at different locations: the etching catalyst promotes etching at the lower surface, while the etching inhibitor prevents excessive etching at the upper surface, creating the desired inverted trapezoidal shape with upper surface width greater than or equal to lower surface width
Solution Approach 2:
The etching solution composition is specifically adjusted by controlling the concentration ratio of etching catalyst to etching inhibitor, and adjusting pH value and temperature, to achieve the unique etching profile where the upper surface width is maintained to be equal to or larger than the lower surface width
2Productivity
If the upper surface width of the conductor layer is made larger than the lower surface width, then inter-wiring distance can be reduced, but the etching process becomes more difficult to control
Solution Approach 1:
The etching solution formulation creates a self-regulating etching process where the catalyst and inhibitor work together to automatically control the etching profile, ensuring the upper surface width remains equal to or larger than the lower surface width without requiring complex process adjustments
Solution Approach 2:
The etching solution is formulated as a composite system containing multiple components including etching catalyst, etching inhibitor, chelating agent, and pH buffer, which work synergistically to achieve precise control over the conductor layer shape
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 enables the formation of wiring substrates with increased density by ensuring the upper surface width is larger than the lower surface width, and the lower surface width is larger than the middle portion width, effectively reducing inter-wiring distances and enhancing the packing density of conductor layers.
Implementation Method 1
The forming of the conductor layer includes etching the copper plating film formed on the substrate such that part of the copper plating film is removed
Implementation Method 2
utilizing a copper chloride etching solution with an etching inhibitor to control the etching rate and achieve the desired shape
Implementation Method 3
forming a copper plating film on the entire surface of a substrate
Data Source
AI summary
A wiring substrate includes a substrate, and a conductor layer formed on the substrate and including copper such that the conductor layer is patterned. The conductor layer is formed such that the upper surface of the conductor layer has a width that is equal to or larger than a width of the lower surface of the conductor layer and that the width of the lower surface is larger than the minimum width of a middle portion of the conductor layer between the upper surface and the lower surface.