IC Package Lead Overhang and Ridge Interlock
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Solution Overview
Problem
Conventional integrated circuit packaging technologies face challenges in achieving high lead density and structural integrity, particularly in compact designs, leading to issues like lead pull-out and weak lead pull strength, which are not adequately addressed by existing solutions.
Innovation Solution
The development of an integrated circuit packaging system that includes a package paddle with a lead overhang and ridge structure, where the lead is connected to an electrical connector and encapsulated under the overhang, enhancing interlocking features and pull strength through a mold interlock mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional packaging technologies are used, then manufacturing simplicity is maintained, but lead density increases are limited and structural integrity deteriorates
Solution Approach 1:
The leadframe is segmented into modular components including a package paddle, multiple leads with overhangs, and ridges. This segmentation allows each component to be optimized independently for its specific function while maintaining overall structural integrity and enabling high lead density through efficient space utilization.
Solution Approach 2:
The lead structure extends into the vertical dimension with overhangs protruding from the lead body and ridges forming raised portions. This three-dimensional configuration increases lead density by utilizing vertical space rather than only horizontal arrangement, while the overhangs and ridges provide additional structural reinforcement.
2Area of stationary object
If lead density is increased to reduce package footprint, then package size is reduced, but lead pull strength decreases
Solution Approach 1:
Each lead is segmented into distinct functional portions: a body portion for electrical connection, an overhang portion protruding from the body, and a ridge portion forming a raised structure. This segmentation allows the overhang and ridge to provide mechanical reinforcement specifically at the lead-encapsulation interface, compensating for the reduced overall lead size necessary for high density.
Solution Approach 2:
The leadframe structure combines metal leads with an encapsulation material that forms an interlocking mechanism. The encapsulation material surrounds and bonds to both the lead body and the overhang/ridge portions, creating a composite structure where the metal provides electrical conductivity and the encapsulation provides mechanical reinforcement, thereby increasing lead pull strength despite reduced lead dimensions.
3Area of stationary object
If package size is reduced for compact devices, then footprint area decreases, but structural integrity and surface mounting capability deteriorate
Solution Approach 1:
The package utilizes vertical dimensionality through lead overhangs and ridges that protrude from the planar leadframe structure. This allows the package to maintain a small footprint while developing mechanical strength in the vertical direction, enabling robust surface mounting capability through the interlocking engagement of overhangs and ridges with the encapsulation and PCB.
4Ease of manufacture
If conventional leadframe structures are used, then manufacturing simplicity is maintained, but manufacturing scalability is limited
Solution Approach 1:
The leadframe is designed as a segmented modular structure where standard formation processes can be applied to create repeating units of leads with overhangs and ridges. This modularity enables scalable manufacturing through techniques such as stamping, etching, or additive manufacturing, allowing high-volume production while maintaining manufacturing simplicity through standardized processes.
Data Source
AI summary
A method of manufacture of an integrated circuit packaging system includes: forming a package paddle; forming a lead adjacent the package paddle, the lead having a lead overhang protruding from a lead non-horizontal side and a lead ridge protruding from the lead non-horizontal side; mounting an integrated circuit over the package paddle; connecting an electrical connector to the lead and the integrated circuit; and forming an encapsulation over the integrated circuit, the lead, and the package paddle, the encapsulation under the lead overhang.