Layered Lead Frame Oxidation Prevention
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Solution Overview
Problem
Electronic components face challenges in achieving reliable bonding between gold and aluminum bond wires and lead frames due to oxidation issues with copper and nickel materials, especially at high temperatures, which affects electrical conductivity and increases production costs.
Innovation Solution
A lead frame assembly with a base layer of copper or iron, a nickel layer, a palladium layer, and a gold layer is used, where the nickel and gold layers inhibit oxidation and provide reliable bonding for both gold and aluminum bond wires, allowing for efficient transmission of high current signals without the high cost of gold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper or nickel materials are used in the lead frame, then electrical conductivity is improved, but oxidation occurs at high temperatures reducing reliability
Solution Approach 1:
The lead frame employs a multi-layer composite structure with copper or nickel base layer providing electrical conductivity, nickel intermediate layer preventing oxidation, and gold outer layer providing oxidation resistance and bonding reliability. This composite approach allows the material to simultaneously achieve good electrical conductivity and oxidation resistance that single materials cannot provide.
2Reliability
If gold layers are used extensively, then bonding reliability is improved, but production cost increases significantly
Solution Approach 1:
The gold layer is applied selectively only to the bond wire attachment areas rather than the entire lead frame surface. This localized application provides oxidation resistance and bonding reliability exactly where needed for wire bonding, while minimizing gold material usage and associated costs. The copper/nickel base layers provide conductivity in areas where gold is not required.
3Ease of manufacture
If aluminum bond wires are used, then production cost is reduced, but bonding reliability deteriorates due to oxidation issues
Solution Approach 1:
The nickel and gold layers serve as intermediary protective barriers between the aluminum bond wires and the oxidizable copper/nickel base material. These intermediate layers prevent direct oxidation of the bond wire attachment area, enabling reliable bonding of cost-effective aluminum bond wires while maintaining oxidation resistance through the protective nickel and gold coating layers.
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 ensures reliable bonding and prevents oxidation, enabling efficient transmission of high current signals while reducing production costs by utilizing less expensive aluminum bond wires, thus addressing the challenges of oxidation and cost in existing technologies.
Implementation Method 1
the nickel and gold layers inhibit oxidation
Implementation Method 2
provide reliable bonding for both gold and aluminum bond wires
Data Source
AI summary
An electronic component and method of making an electronic component is disclosed. In one embodiment, the electronic component includes a frame having a base layer, a first layer, a second layer including palladium placed on the first layer, and a third layer including gold placed on the second layer. A semiconductor chip is positioned on the frame.