Wiring Board Dual Underlayer for Even Metal Thickness
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Solution Overview
Problem
Conventional methods for manufacturing wiring boards face challenges in achieving even metal layer thickness and maintaining power transmission efficiency due to high electrical resistance and surface roughness issues in the underlayer, particularly when using low-conductivity materials and high-frequency currents.
Innovation Solution
A method involving a substrate with two conductive underlayers, where the first underlayer has higher electrical conductivity than the second, allowing uniform current flow and selective metal deposition, thereby forming an even metal layer thickness and suppressing power transmission efficiency decreases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single underlayer with low electrical conductivity is used to prevent metal deposition, then metal deposition is suppressed on the underlayer surface, but the underlayer develops high electrical resistance causing uneven current distribution and uneven metal layer thickness
Solution Approach 1:
The underlayer is divided into two separate layers: a first underlayer with low electrical conductivity to prevent metal deposition, and a second underlayer with high electrical conductivity to ensure uniform current distribution. This segmentation resolves the contradiction by assigning different functional requirements to separate layers rather than attempting to satisfy both requirements in a single layer.
Solution Approach 2:
Different regions of the underlayer structure are assigned different electrical conductivity properties. The first underlayer (contacting the insulating substrate) has low conductivity to prevent unwanted metal deposition, while the second underlayer (contacting the seed layer) has high conductivity to ensure uniform current distribution during electroplating. This local differentiation of properties resolves the contradiction between preventing metal deposition and maintaining electrical conductivity.
2Ease of manufacture
If the underlayer has high electrical resistance, then metal deposition can be prevented on non-wiring areas, but current distribution becomes uneven resulting in non-uniform metal layer thickness
Solution Approach 1:
The underlayer is segmented into two functional layers: the first underlayer provides selective metal deposition control through low conductivity, while the second underlayer ensures uniform current distribution through high conductivity. This segmentation allows both selective deposition and thickness uniformity to be achieved simultaneously.
Solution Approach 2:
The underlayer structure uses a composite of two materials with different electrical conductivity characteristics. The first underlayer material has low conductivity for selective deposition, while the second underlayer material has high conductivity for uniform current distribution. This composite structure resolves the contradiction between selective deposition ease and manufacturing precision.
3Manufacturing precision
If a single high-conductivity underlayer is used, then uniform current distribution is achieved, but metal deposits on the underlayer surface where seed layer is absent
Solution Approach 1:
The underlayer is segmented into two layers with different conductivity properties. The first underlayer with low conductivity prevents metal deposition on non-wiring areas, while the second underlayer with high conductivity ensures uniform current distribution. This segmentation resolves the contradiction between current uniformity and selective deposition control.
Solution Approach 2:
Different regions of the underlayer structure have different electrical conductivity properties tailored to local requirements. The first underlayer region has low conductivity to prevent metal deposition, while the second underlayer region has high conductivity to ensure uniform current distribution. This local quality differentiation resolves the contradiction between selective deposition and current uniformity.
4Reliability
If low-conductivity material is used for the underlayer, then metal deposition is prevented, but power transmission efficiency decreases when high-frequency current is supplied
Solution Approach 1:
The underlayer is segmented into two layers: the first underlayer with low conductivity controls metal deposition, while the second underlayer with high conductivity maintains power transmission efficiency. This segmentation resolves the contradiction between deposition control and energy loss by separating these functions into different layers.
Solution Approach 2:
The underlayer structure uses a composite of two materials with different electrical conductivity properties. The first underlayer material provides metal deposition control through low conductivity, while the second underlayer material maintains power transmission efficiency through high conductivity. This composite structure resolves the contradiction between deposition control and energy loss.
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 method ensures even metal layer thickness and maintains power transmission efficiency even with high-frequency currents by using a dual underlayer configuration, enhancing current distribution and reducing noise and unevenness.
Implementation Method 1
disposing a solid electrolyte membrane between an anode and the seed layer as a cathode, pressing the solid electrolyte membrane against at least the seed layer, and applying voltage between the anode and the first underlayer to reduce metal ions contained in the solid electrolyte membrane
Implementation Method 2
a first underlayer disposed on the surface of the substrate and formed of a material having a higher electrical conductivity than that of the second underlayer
Implementation Method 3
applying voltage between the anode and the first underlayer to reduce metal ions contained in the solid electrolyte membrane and so form a metal layer on the surface of the seed layer
Data Source
AI summary
A method for manufacturing a wiring board is capable of forming a metal layer included in a wiring layer to have an even thickness. The method includes preparing a conductive first underlayer on a surface of a substrate; a conductive second underlayer on a surface of the first underlayer; and a seed layer on a surface of the second underlayer and containing metal. The method disposes a solid electrolyte membrane between an anode and the seed layer as a cathode; applies voltage between the anode and the first underlayer to form a metal layer on the surface of the seed layer; removes an exposed portion of the second underlayer without the seed layer from the substrate; and removes an exposed portion of the first underlayer without the seed layer from the substrate. The first underlayer is a material having a higher electrical conductivity than that of the second underlayer.