Two-Stage Etching for Wiring Substrate Insulation
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Solution Overview
Problem
Existing methods for manufacturing wiring substrates face challenges in completely removing metal foils from insulating layers without excessive side etching, leading to residual metal that can decrease insulation between conductor patterns, especially in fine pitch formations.
Innovation Solution
A method involving a two-stage etching process where the first etching process removes the plating film and partially exposes the metal foil, followed by a second etching process that removes the metal foil after removing the etching resist, allowing for precise conductor pattern formation with rounded edges and improved insulation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single etching process is used to remove the plating film and metal foil, then the manufacturing process is simpler, but metal residues remain between conductor patterns decreasing insulation reliability
Solution Approach 1:
The patent divides the etching process into two distinct stages: a first etching process that removes the plating film while leaving the metal foil intact, and a second etching process that removes the metal foil to form the final conductor pattern. This segmentation allows each etching step to be optimized independently, ensuring complete removal of metal residues while maintaining manufacturing feasibility.
2Reliability
If the etching process is optimized to completely remove metal foil, then insulation reliability improves, but excessive side etching occurs distorting conductor pattern shapes
Solution Approach 1:
The first etching process performs a preliminary removal of the plating film layer before the second etching process removes the metal foil. This preliminary action exposes the metal foil surface while maintaining the protective effect of the etching resist during the initial etching stage, preventing excessive side etching and preserving the intended conductor pattern shapes.
Solution Approach 2:
The patent employs periodic action by conducting etching processes at different stages with the etching resist in place during the first etching, then removing the resist before the second etching. This periodic application and removal of the etching resist allows controlled etching at each stage, achieving complete metal foil removal while maintaining pattern precision.
3Manufacturing precision
If the etching resist is removed after both etching processes, then the conductor pattern is fully formed, but metal residues remain in fine pitch formations
Solution Approach 1:
The patent segments the etching process into two distinct operations: the first etching process removes the plating film while the etching resist is still in place, and the second etching process removes the metal foil after the etching resist has been removed. This segmentation ensures that in fine pitch formations, the metal foil is completely removed without leaving residues, while the conductor pattern shapes are maintained throughout the process.
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 effectively removes metal residues between conductor patterns, enhancing insulation reliability and maintaining intended conductor pattern shapes, even in dense wiring configurations.
Implementation Method 1
an electroless copper plating layer and an electrolytic copper plating layer is formed on an insulating layer
Implementation Method 2
an electroless copper plating layer and an electrolytic copper plating layer is formed on an insulating layer
Implementation Method 3
conducting a first etching process such that part of the plating film exposed from the opening of the etching resist is removed
Data Source
AI summary
A method for manufacturing a wiring substrate includes forming a plating film on a metal foil laminated on a surface of an insulating layer, forming an etching resist on the plating film such that the etching resist has an opening for forming a conductor pattern, conducting a first etching process such that part of the plating film exposed from the opening of the etching resist is removed and that part of the metal foil is exposed, removing the etching resist from the plating film on the metal foil laminated on the surface of an insulating layer, and conducting a second etching process such that the part of the metal foil exposed by the first etching process is removed and that a conductor layer having the conductor pattern is formed on the surface of the insulating layer.