Coplanar Leadframe Singulation for Multi-Row IC Packages
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Solution Overview
Problem
Multi-row leadframes present complexity in lead separation and non-planar design, which complicates the separation process and risks the reliability of chip packages, necessitating a solution to reduce complexity and improve efficiency.
Innovation Solution
A semiconductor package system with a leadframe featuring coplanar inner and outer frame bars, tiebars, and rows of leads, where the semiconductor chip is attached to a die pad and bonded with wires, encapsulated, and then singulated by cutting grooves to remove inner and outer frame bars, simplifying the separation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-row leadframes are used to provide additional leads, then the quantity of leads increases, but the complexity of lead separation increases and reliability decreases
Solution Approach 1:
The leadframe is segmented into modular units with standardized lead configurations. Each leadframe module contains a specific number of leads arranged in a consistent pattern, allowing complex multi-row configurations to be built from simpler repeating units. This segmentation reduces the overall complexity of lead separation by breaking down the intricate multi-row structure into manageable segments that can be processed systematically.
Solution Approach 2:
The leadframe structure is pre-configured with leads temporarily attached to a die attach paddle before final packaging. This preliminary arrangement allows all leads to be positioned and secured in their final configurations before the encapsulation process, eliminating the need for complex post-encapsulation lead separation operations. The preliminary action of attaching leads to the die attach paddle simplifies the overall manufacturing process and reduces separation complexity.
2Reliability
If non-planar leadframe structure is used to prevent cutting of outer row leads, then the reliability of lead protection improves, but the complexity of leadframe design and separation process increases
Solution Approach 1:
The leadframe transitions from a non-planar three-dimensional structure to a planar two-dimensional structure. By arranging all leads and the die attach paddle in a single plane, the design eliminates the complexity of multi-level configurations while maintaining adequate protection for outer row leads through the planar layout and encapsulation process. This dimensional simplification reduces design complexity without sacrificing lead protection reliability.
Solution Approach 2:
The leadframe uses a standardized planar template that can be repeatedly copied and manufactured. Instead of custom non-planar designs for each application, a proven planar leadframe configuration serves as a master template that can be replicated across different packages. This copying approach simplifies design by eliminating the need for complex custom non-planar structures while maintaining consistent lead protection through the standardized planar configuration.
3Reliability
If non-planar leadframe structure is used to prevent cutting of outer row leads, then the protection of leads during separation improves, but the efficiency of the separation process decreases
Solution Approach 1:
All leads are temporarily attached to the die attach paddle before the encapsulation and separation processes. This preliminary attachment secures leads in their final positions and protects them during subsequent manufacturing steps. By performing this attachment action beforehand, the actual separation process becomes simpler and more efficient, as leads are already protected and positioned correctly, eliminating the need for complex protective measures during separation.
Solution Approach 2:
The transition to a planar two-dimensional leadframe structure enables more efficient separation processes compared to non-planar three-dimensional configurations. The planar layout allows for straightforward cutting and separation operations using standard manufacturing equipment, whereas non-planar structures would require complex multi-axis machining and handling. This dimensional simplification maintains lead protection through the planar encapsulation while dramatically improving separation process efficiency.
Data Source
AI summary
A semiconductor package system includes: providing a leadframe having inner frame bars, outer frame bars, a die pad, tiebars, and rows of leads, the inner frame bars being coplanar with outer frame bars; attaching a semiconductor chip to the die pad; attaching bond wires between the semiconductor chip and the rows of leads; encapsulating the semiconductor chip, the bond wires, the inner frame bars, the outer frame bars, the die pad, the tiebars, and the rows of leads in an encapsulant; cutting a groove to remove the inner frame bars; and singulating the leadframe and the encapsulant to remove the outer frame bars.