Wiring Circuit Board Nickel Layers for Corrosion Protection
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Solution Overview
Problem
The existing circuit boards with nickel metal thin films require excessive time to remove unnecessary portions, leading to decreased producing efficiency and potential corrosion of the conductive circuits.
Innovation Solution
A wiring circuit board design with a first nickel layer containing 6% by mass or less phosphorus between the wire and insulating layer, allowing easy removal and protection from corrosion, and a second nickel layer with higher phosphorus content for terminal protection, enhancing design freedom and preventing gold diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal thin film is formed on the entire surface of the conductive circuit and then the cover layer is formed, then the wire can be protected from corrosion, but the time to remove unnecessary portions becomes excessive and producing efficiency decreases
Solution Approach 1:
The patent applies local quality by forming the nickel layer only on specific portions of the conductive circuit (wire surfaces) rather than the entire surface. This selective plating ensures corrosion protection where needed while minimizing the amount of material to be removed later, thereby maintaining producing efficiency.
Solution Approach 2:
The patent extracts the unnecessary nickel layer formation by using a resist pattern to prevent nickel deposition on specific areas. This allows the nickel layer to be formed only on necessary portions, eliminating the time-consuming step of removing excessive nickel from the entire surface.
2Reliability
If the nickel layer is formed to cover the terminal, then the terminal is protected, but the removal of unnecessary nickel takes excessive time
Solution Approach 1:
The patent applies local quality by differentiating the nickel layer formation for different regions: a first nickel layer with low phosphorus content (0-6%) is formed on wire portions requiring corrosion protection, while a second nickel layer with high phosphorus content (7-15%) is formed on terminal portions. This differentiation enables selective removal and reduces overall removal time.
Solution Approach 2:
The patent changes the phosphorus content parameter of the nickel layer to achieve different functional characteristics. By controlling phosphorus content between 0-6% for wire protection and 7-15% for terminal protection, the patent optimizes both protection effectiveness and removal efficiency.
3Reliability
If the first nickel layer contains high phosphorus content, then the wire protection is enhanced, but the removal of unnecessary portions becomes difficult and time-consuming
Solution Approach 1:
The patent changes the phosphorus content parameter to optimize both protection and removal characteristics. By limiting phosphorus content in the first nickel layer to 0-6%, the patent maintains adequate wire protection while ensuring easy and quick removal of unnecessary portions, avoiding the manufacturing difficulties associated with high phosphorus content.
4Device complexity
If a single nickel layer is used for both wire and terminal protection, then the process is simplified, but the design freedom and specialized protection are reduced
Solution Approach 1:
The patent segments the nickel layer formation into two distinct layers: a first nickel layer (0-6% phosphorus) for wire protection and a second nickel layer (7-15% phosphorus) for terminal protection. This segmentation provides specialized protection for each component while maintaining a relatively simple two-step plating process.
Solution Approach 2:
The patent applies local quality by tailoring the nickel layer composition to specific locations: low phosphorus content (0-6%) for wire portions requiring corrosion protection and high phosphorus content (7-15%) for terminal portions requiring different protective characteristics. This enables optimized protection for each region while maintaining process feasibility.
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 solution effectively suppresses wire corrosion while maintaining production efficiency by using a phosphorus-adjusted nickel layer and a separate nickel layer for terminals, ensuring crack prevention and gold stability.
Implementation Method 1
The metal thin film is made of nickel formed by electroless plating
Implementation Method 2
the first nickel layer covering the terminal can easily be removed by etching
Implementation Method 3
the diffusion of gold into the terminal can be suppressed
Data Source
AI summary
A wiring circuit board includes a first insulating layer, a conductive pattern, a second insulating layer, and a first nickel layer disposed between a wire and the second insulating layer and covering the wire without covering the terminal. The first nickel layer contains phosphorus, and the content ratio of phosphorus in the first nickel layer is 6% by mass or less.