Segmented Lead Frame with Bimetallic Interface for Press-Fit Control
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Solution Overview
Problem
Conventional lead frames made from a single material compromise between high electrical conductivity for power leads and elasticity for press-fit control leads, resulting in suboptimal performance and increased material cross sections, which affects both electrical resistance and mechanical strength.
Innovation Solution
A lead frame comprising power terminals made from a highly conductive material and control terminals made from an elastic material, formed into sub-lead frames that are bonded together at a bimetallic interface using methods like laser welding or epoxy resins, allowing for tailored properties and reduced material cross sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single material is used for the entire lead frame, then manufacturing simplicity is maintained, but electrical conductivity for power leads and elasticity for control leads cannot both be optimized
Solution Approach 1:
The lead frame is divided into multiple sub-lead frames, each made from materials optimized for specific functions. Power leads use highly conductive materials while control leads use elastic materials suitable for press-fit connectors, allowing each segment to be independently optimized for its intended purpose.
Solution Approach 2:
The lead frame employs a composite structure combining different metallic materials within a single integrated component. This allows the simultaneous presence of materials with high electrical conductivity for power transmission and materials with high elasticity for press-fit control leads, resolving the contradiction between manufacturing simplicity and performance optimization.
2Reliability
If pure copper is used for power leads to maximize electrical conductivity, then current carrying capability is improved, but elasticity required for press-fit control leads is reduced
Solution Approach 1:
Different regions of the lead frame are assigned different material properties according to their specific functional requirements. Power leads are made from pure copper or highly conductive alloys for maximum electrical conductivity, while control leads are made from elastic materials with appropriate tensile strength for press-fit applications, allowing each local region to have the optimal material characteristics.
3Device complexity
If a single material lead frame is used, then material selection is simplified, but material cross sections must be increased to satisfy both power and control lead requirements
Solution Approach 1:
The lead frame is segmented into function-specific sub-lead frames that can be manufactured separately and then assembled. This segmentation allows each segment to use the minimum necessary material cross section optimized for its specific function, reducing overall material usage while maintaining the ability to meet both power and control lead requirements.
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 better electrical conductivity for power terminals and high elasticity for control terminals, minimizing material usage and allowing for separate plating processes without masks, while maintaining existing molding and forming processes.
Implementation Method 1
bonded together at a bimetallic interface using methods like laser welding or epoxy resins
Implementation Method 2
bonded together at a bimetallic interface using methods like laser welding or epoxy resins
Data Source
AI summary
A lead frame is provided, including one or more power terminals and one or more control terminals, wherein at least one of the control terminals is externally terminated with a press-fit contact member, and wherein at least one of the control terminals and at least one power terminals are formed from different materials. With the disclosed lead frame of the invention, lower material cross sections in the power terminals will be provided because of the better electrical conductivity when using pure copper compared to alloys with higher mechanical strengths. Also specific/different plating could be added to the individual needs of the different pin types without using masks in the plating process.