Reactive-Coated Press-In Pin for Whisker-Free Electrical Joining
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Solution Overview
Problem
Existing press-in pin technologies for electrical contacting arrangements face challenges with high compressive stresses leading to mechanical damage and the formation of tin whiskers, which result in errors such as deformation, short circuits, and reduced reliability.
Innovation Solution
A press-in pin with a reactive multilayer coating, comprising materials like aluminum and nickel, that undergoes an exothermic reaction upon activation by an energy pulse, forming a material-locking connection with the metallized plated-through hole without significant compressive stress, thereby eliminating whisker formation and mechanical damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tin-based coating is used to achieve material connection and high reliability, then the connection resilience is improved, but tin whisker formation occurs leading to short circuits
Solution Approach 1:
The patent changes the material composition parameters of the coating by replacing tin-based materials with nickel and copper combinations. The nickel layer provides the necessary mechanical properties and the copper layer ensures electrical conductivity, achieving reliable connection without tin whisker formation through parameter modification of the coating system.
Solution Approach 2:
The patent applies a composite coating structure consisting of multiple layers (nickel layer and copper layer) with distinct functions. The nickel layer provides mechanical strength and frictional connection, while the copper layer provides electrical conductivity and material connection through diffusion bridges, achieving reliable connection without tin whiskers through composite material design.
2Strength
If high compressive stress is applied to achieve strong electromechanical connection, then the connection strength is improved, but mechanical damage occurs such as deformation and cracks
Solution Approach 1:
The patent changes the surface property parameters by applying nickel and copper coatings with optimized thicknesses and mechanical properties. This allows achieving strong electromechanical connection through improved surface friction and diffusion bonding without requiring excessive compressive stress that would cause mechanical damage to the substrate.
3Reliability
If tin-lead-based coating is used to achieve material connection, then the connection reliability is improved, but lead content increases environmental harm
Solution Approach 1:
The patent changes the chemical composition parameters of the coating by completely eliminating lead and tin from the coating system. The nickel-copper composite coating achieves equivalent or superior connection reliability through diffusion bridges and frictional connection without any lead content, resolving the environmental harm issue.
4Ease of operation
If friction-reducing lubricant layers are applied to nickel surfaces, then the ease of insertion is improved, but the material connection capability is reduced
Solution Approach 1:
The patent changes the surface property parameters by controlling the thickness and properties of the nickel layer. The nickel layer is designed with optimized thickness (0.5-5 μm) and surface characteristics that provide sufficient friction for material connection through diffusion bridges without requiring additional lubricant layers, thus maintaining both insertion ease and connection strength.
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 solution enables a highly resilient, gas-tight connection with reduced joining forces, minimizing structural changes and avoiding common errors in press-in technology, while reducing the risk of whisker formation and mechanical stress, thus enhancing the reliability and design flexibility of the electrical contacting arrangement.
Implementation Method 1
The coating comprises a reactive multilayer applied to the press-in pin... that undergoes an exothermic reaction upon activation by an energy pulse
Data Source
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Figure 5~6
AI summary
The invention relates to a press-in pin (10) for an electrical contacting assembly (1), having an elastic press-in region (12) and an electrically conductive coating (14). The invention further relates to a corresponding contacting assembly (1), and to a method for joining a press-in pin (10) and a metallized via (7). The coating (14) comprises a reactive multi-layer applied to the press-in pin (10) and a first contact layer applied to the reactive multi-layer.