Leadframe With Stepped Outer Frame For Thinner Devices
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Solution Overview
Problem
Conventional leadframes face challenges in reducing thickness while maintaining stiffness, which affects the performance of semiconductor devices, as both the product and non-product regions have the same thickness, leading to potential deformation and difficulties in modifying the shape or material to address this issue.
Innovation Solution
A leadframe design where the outer frame part is thicker than the individual regions, with a stepped structure and uneven surface features, allowing for reduced thickness of the product regions while maintaining stiffness and enhancing adhesion with resin through increased surface area, thereby preventing delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the leadframe is reduced to produce thinner semiconductor devices, then the device thickness is improved, but the leadframe stiffness deteriorates causing deformation
Solution Approach 1:
The leadframe is designed with non-uniform thickness where the outer frame part maintains greater thickness for stiffness while the individual region thickness is reduced for thinner devices. This local differentiation allows simultaneous optimization of both device thickness and leadframe stiffness.
Solution Approach 2:
The leadframe is divided into two functional regions with different thickness characteristics: the outer frame part and the individual region. This segmentation allows each part to be optimized independently - the outer frame for structural support and the individual region for device thinness.
2Length of moving object
If the thickness of the leadframe is reduced, then the device thickness is improved, but the adhesion with resin deteriorates leading to delamination
Solution Approach 1:
Instead of increasing thickness in the vertical dimension to improve adhesion, the invention creates an uneven surface with increased surface area through lateral dimensional changes. The uneven surface features extend the adhesion interface area without increasing the overall device thickness.
Solution Approach 2:
The surface of the individual region is made uneven with varying height to locally increase the adhesion area. This local surface modification enhances resin bonding while maintaining the overall thin profile of the device.
3Length of moving object
If the thickness of the leadframe is reduced, then the device thickness is improved, but the manufacturing complexity increases due to required shape modifications
Solution Approach 1:
The invention changes the thickness parameter from uniform to non-uniform, and creates an uneven surface profile. These parameter variations are achieved through standard etching processes, maintaining manufacturing simplicity despite the complex final geometry.
Data Source
AI summary
A leadframe includes an individual region to become a semiconductor device, and an outer frame part supporting the individual region through its peripheral edge. The thickness of the outer frame part is greater than the thickness of the individual region.