Leadframe Sacrificial Anode Coating for Corrosion Protection
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Solution Overview
Problem
Conventional leadframes suffer from oxidation and corrosion issues that affect bondability and signal transition, with existing solutions impacting other properties and being unsatisfactory.
Innovation Solution
A leadframe design featuring a functional area with a first standard electrode potential and a non-functional area with a protective layer acting as a sacrificial anode, having a lower second standard electrode potential, to protect the functional area from corrosion and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the alloying condition of the leadframe is changed to prevent oxidation/corrosion, then the corrosion resistance is improved, but other properties of the leadframe are affected
Solution Approach 1:
The leadframe is divided into functional areas and non-functional areas, with the protective layer applied selectively to non-functional areas only. This segmentation allows corrosion protection without compromising the material properties of functional areas that require specific electrical or mechanical characteristics.
Solution Approach 2:
The protective layer is applied locally to non-functional areas rather than uniformly across the entire leadframe. This local quality approach provides corrosion protection where needed while preserving the original material properties of functional areas that require specific conductivity, bondability, or other performance characteristics.
2Reliability
If a protective layer is added to the leadframe to prevent oxidation/corrosion, then the corrosion resistance is improved, but the device complexity increases
Solution Approach 1:
The protective layer is segmented to cover only non-functional areas of the leadframe, excluding functional areas that require direct exposure or specific surface properties. This selective application reduces the overall complexity compared to a complete coating while maintaining effective corrosion protection.
Solution Approach 2:
The protective layer acts as an intermediary sacrificial anode that chemically interacts with the environment to protect the underlying functional areas. This mediator approach provides corrosion protection through electrochemical mechanisms without requiring complex multi-layer structures or additional protective systems.
3Reliability
If the protective layer covers the functional area, then the corrosion protection is improved, but the bondability and signal transition are affected
Solution Approach 1:
The leadframe surface is segmented into functional areas (requiring direct bonding and signal transmission) and non-functional areas (requiring corrosion protection). The protective layer is applied only to non-functional areas, eliminating interference with bondability and signal transition while providing comprehensive corrosion protection where needed.
Solution Approach 2:
Different surface qualities are applied to different areas: functional areas maintain their original material properties for optimal bonding and electrical performance, while non-functional areas receive the protective layer for corrosion resistance. This local differentiation resolves the contradiction between protection and performance.
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 protective layer effectively prevents corrosion and oxidation of the functional area without altering its material properties, ensuring reliable bondability and signal transmission.
Implementation Method 1
a protective layer having a second standard electrode potential lower than the first standard electrode potential and acting as a sacrificial anode to protect the functional area as a cathode from corrosion/oxidation
Data Source
AI summary
A leadframe (10) comprises: a functional area (12) having a first standard electrode potential; and a non-functional area (14) adjacent to the functional area (12) and including a protective layer, the protective layer (16) having a second standard electrode potential lower than the first standard electrode potential and acting as a sacrificial anode to protect the functional area (12) as a cathode from corrosion/oxidation. Embodiments of the present disclosure may help to protect functions of the leadframe (10) from affections of corrosion/oxidization, etc.