Lead Frame Support Lead Geometry for Transport Deformation Resistance
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Solution Overview
Problem
Existing lead frames for electronic components, such as DFN packages, are prone to deformation due to shocks during transportation, which can deteriorate the characteristics of the electronic components.
Innovation Solution
A lead frame design that includes a die pad, a plurality of leads, at least one support lead, and a frame member surrounding these components. The support lead is configured to have a cross-sectional second-order moment that is equal to or more than that in a perpendicular direction, making it less susceptible to bending and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If leads are made long in one direction to facilitate mounting and electrical connection, then ease of operation and electrical connectivity are improved, but the leads become more susceptible to deformation during transportation
Solution Approach 1:
The support lead is designed with asymmetric cross-sectional dimensions where the first dimension (width) is greater than the second dimension (thickness), creating an asymmetric I-shaped or rectangular cross-section. This asymmetric geometry provides greater moment of inertia against bending in the critical direction, reducing deformation while maintaining the lead's functional length for mounting and electrical connection.
Solution Approach 2:
The invention addresses the deformation problem by modifying the cross-sectional dimensions of the support lead rather than changing its length. By increasing the first cross-sectional dimension (width) relative to the second dimension (thickness), the lead gains enhanced bending resistance in the direction perpendicular to its length, thereby improving structural stability without compromising the ease of mounting and electrical connectivity provided by its longitudinal extent.
2Reliability
If the cross-sectional second-order moment of the support lead is increased to resist deformation, then reliability is improved, but device complexity increases
Solution Approach 1:
The asymmetric cross-sectional design is applied specifically to the support lead that connects the specific lead to the second connection bar, rather than to all leads in the assembly. This localized application of enhanced structural properties targets the critical deformation-prone section while keeping the rest of the lead frame structure simple and easy to manufacture.
Solution Approach 2:
The invention achieves improved reliability by changing the geometric parameters of the support lead's cross-section, specifically making the first dimension (width) greater than the second dimension (thickness). This parameter change increases the cross-sectional second-order moment and moment of inertia, providing greater resistance to deformation without requiring complex structural modifications or additional components.
Data Source
AI summary
A lead frame includes a die pad, a plurality of leads, at least one support lead, and a frame member. The frame member includes two first connection bars and two second connection bars. The plurality of leads include a plurality of specific leads. The plurality of specific leads are each connected to the first connection bar. At least one of the specific leads is connected to the second connection bar via the at least one support lead. The cross-sectional second-order moment of a cross section of the at least one support lead perpendicular to a Y direction around an X axis is equal to or more than the cross-sectional second-order moment of a cross section of the at least one support lead perpendicular to an X direction around a Y axis.