Complementary Leadframe Strip Layout for Deformation Resistance
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Solution Overview
Problem
Conventional leadframe strip designs for large semiconductor packages suffer from deformation and issues like no-stick on lead or pad during wire bonding and mold flash, particularly in flipchip packages, due to the uniformity of unit designs leading to mechanical instability.
Innovation Solution
Implementing leadframe strips with sets of complementary leadframe unit designs that create a stronger metal support network through continuous metal networks spanning the entire strip, using different tie bar configurations for mechanical support without affecting electrical functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform unit design is used throughout the leadframe strip, then manufacturing simplicity is improved, but mechanical stability deteriorates leading to deformation
Solution Approach 1:
The patent applies local quality by varying the tie bar configurations in different leadframe units along the strip. Specifically, alternating between Unit Type A (with first and second tie bars) and Unit Type B (with only first tie bars), creating localized structural differences that collectively enhance the overall mechanical stability of the strip while maintaining manufacturing simplicity through a repeating pattern.
2Strength
If complementary unit designs are implemented, then mechanical robustness is improved, but device complexity increases
Solution Approach 1:
The patent segments the leadframe strip into alternating units of two types (Type A and Type B), where each unit type has a specific tie bar configuration. This segmentation creates a modular design that enhances mechanical robustness through the complementary nature of the alternating units, while the repetitive segmented pattern actually simplifies the overall design process compared to a completely unique design for each unit.
Data Source
AI summary
A leadframe strip includes a two-dimensional mechanically interconnected array of leadframe units including a plurality of leadframe unit pairs, the leadframe strip having an overall length and an overall width. The plurality of leadframe unit pairs each include a first leadframe design including a first plurality of tie bars and a plurality of first leads, and a second leadframe design that is different from the first leadframe design including a second plurality of tie bars, and a plurality of second leads. The first plurality of tie bars and the second plurality of tie bars are configured together to provide a plurality of continuous metal support networks that span an entirety of the overall length or the overall width.