Switch Contact Element With Discontinuous Precious Metal Layer
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Solution Overview
Problem
Traditional contact components in switches and keypads face challenges in simultaneously maintaining mechanical properties, electrical conductivity, and cost-effectiveness, with issues related to dust and oil stain resistance and high precious metal consumption.
Innovation Solution
The development of switch contact components with a three-layer structure comprising a rubber underlayer, a continuous base metal mid-layer, and a discontinuous precious metal or bimetallic composite upper layer, featuring stripes, dots, or lattices for enhanced conductivity and reduced precious metal usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a precious metal layer is used as the contact material, then electrical conductivity and chemical stability are improved, but cost increases significantly
Solution Approach 1:
The patent applies different metal materials to different regions of the contact component. The surface layer uses precious metals (gold, silver, or copper) only where electrical contact is needed, while the bulk uses base metals (stainless steel, aluminum alloy, or titanium alloy). This localized application of precious metals maintains electrical conductivity at contact points while dramatically reducing overall material cost.
Solution Approach 2:
The patent creates a composite structure combining base metal and precious metal layers. The surface layer (0.5-5 μm thick) contains precious metals for conductivity, while the substrate provides mechanical strength. This composite approach achieves both electrical performance and cost efficiency by optimizing material distribution across different functional zones.
2Quantity of substance
If a base metal is used as the contact material, then cost is reduced, but electrical conductivity and chemical stability deteriorate
Solution Approach 1:
The patent concentrates precious metals specifically at the contact surface where electrical conduction occurs, while using cost-effective base metals for the bulk structure. This localized quality differentiation ensures high conductivity where needed while maintaining overall cost efficiency through base metal utilization in non-critical areas.
Solution Approach 2:
The composite structure combines base metal substrate with precious metal surface coating. The base metal provides mechanical properties and cost efficiency, while the precious metal layer (0.5-5 μm) provides the necessary electrical conductivity and chemical stability at the contact interface, resolving the contradiction between cost and performance.
3Reliability
If a thick precious metal layer is applied to increase surface area for better conductivity, then electrical conductivity is improved, but precious metal consumption increases
Solution Approach 1:
The patent applies precious metals locally only where electrical contact is required, rather than uniformly across the entire surface. The surface layer thickness is optimized at 0.5-5 μm, providing sufficient conductivity while minimizing material usage. This localized application eliminates unnecessary precious metal consumption in areas where conductivity is not critical.
Solution Approach 2:
The patent optimizes the thickness parameter of the precious metal layer to 0.5-5 μm, finding the optimal balance between electrical conductivity and material consumption. This parameter optimization ensures adequate conductivity performance while significantly reducing precious metal usage compared to traditional thicker coatings.
4Strength
If a roughened metal surface is used to increase bonding area with rubber, then bonding strength is improved, but precious metal consumption increases due to larger surface area
Solution Approach 1:
The patent applies the roughened surface treatment selectively to the base metal substrate layer, not to the precious metal surface layer. This allows the roughened surface to provide enhanced bonding with the rubber substrate while the smooth precious metal layer maintains low material consumption and optimal electrical conductivity at the contact surface.
Solution Approach 2:
The composite structure separates the bonding function from the conductivity function. The base metal substrate with roughened surface provides mechanical bonding with rubber, while the precious metal surface layer provides electrical conductivity with minimal thickness (0.5-5 μm). This functional separation allows bonding strength enhancement without increasing precious metal consumption.
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 provides improved mechanical strength, dust and oil stain resistance, reduced precious metal consumption, and increased reliability in circuit conduction, while maintaining effective electrical conductivity at a lower cost.
Implementation Method 1
Gold, silver and other precious metals have good electrical conductivity
Implementation Method 2
an adhesive is coated, to the upper surface of a baseplate
Data Source
AI summary
A switch contact element, having a layered structure comprising three layers: the bottom layer is silicone rubber, the middle layer is a continuous base metal sheet layer, and the upper layer is a discontinuous (stripe-shaped, raised-point-shaped or lattice-shaped) precious metal plated layer or a double-metal composite layer of a discontinuous base metal plated layer and a precious metal plated layer. The thickness of the bottom layer is greater than that of the middle layer, the thickness of the middle layer is greater than that of the upper layer, and the thickness of the upper layer meets the conditions that the conductive current is greater than safe current of conductive contacts on a circuit board, and the service life of a switch for the design is ensured.