IC Package Pad Extension and Conductive Layer for Solder Creep Control
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Solution Overview
Problem
Current integrated circuit packaging technologies face challenges in achieving high lead density, structural integrity, and efficient surface mount technology performance, particularly due to issues with solder creep and non-uniform solder distribution, which hinder the scalability and miniaturization of chip packaging.
Innovation Solution
The proposed solution involves a packaging system with a package paddle, pad extension, and conductive layer that provides electrical connections while resisting solder creep, featuring a conductive layer formed directly on and between the package paddle and pad extension, and an integrated circuit connected to both the pad extension and lead, ensuring uniform solder distribution and preventing solder creep during surface mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional leadframe packaging is used to achieve electrical connections, then electrical interconnect functionality is provided, but lead density is limited and package footprint area is large
Solution Approach 1:
The patent transitions from two-dimensional leadframe layouts to three-dimensional vertical stacking with multiple lead levels connected via vias through the substrate. This dimensional change allows significantly higher lead density within the same package footprint area, as leads are arranged in multiple tiers rather than single-plane configurations.
Solution Approach 2:
The patent implements nested structures where multiple lead levels are stacked vertically within the package substrate, with lower leads nested beneath upper leads. The vias penetrate through the substrate to connect these nested lead levels, enabling high-density interconnection without increasing the package footprint.
2Area of stationary object
If lead density is increased to reduce package size, then package footprint is reduced, but manufacturing scalability is limited
Solution Approach 1:
The patent segments the leadframe into modular units that can be independently manufactured and then assembled into the final package. The leadframe is divided into separate sections that are processed individually through stamping and forming operations, improving manufacturing scalability while maintaining high lead density in the final assembled package.
Solution Approach 2:
The patent performs preliminary forming of the leadframe structure before final assembly, including pre-stamping lead patterns and pre-forming connection points. This preliminary action enables more complex high-density configurations to be achieved through standardized preprocessing steps that can be scaled across production volumes.
3Area of stationary object
If package size is reduced for miniaturization, then compactness is improved, but structural integrity is compromised
Solution Approach 1:
The patent employs composite packaging structures combining substrate materials, leadframe materials, and encapsulant materials with complementary mechanical properties. The substrate provides rigid support for vertical stacking, while the encapsulant material fills voids and distributes mechanical stresses, maintaining structural integrity in miniaturized packages.
Solution Approach 2:
The nested vertical stacking of leads within the substrate creates a structurally reinforced configuration where multiple lead levels mutually support each other. This nested arrangement distributes mechanical loads throughout the three-dimensional structure, enhancing overall structural integrity despite reduced package dimensions.
4Productivity
If surface mount technology is implemented for efficient mounting, then mounting speed is improved, but solder creep and non-uniform distribution occur
Solution Approach 1:
The patent implements local quality variations in the substrate and leadframe design, with strategically placed solder resist patterns and varied lead configurations at different locations. This local differentiation controls solder flow during reflow processing, preventing solder creep while ensuring uniform solder distribution across all connection points during automated surface mount operations.
Data Source
AI summary
A method of manufacture of an integrated circuit packaging system includes: providing a package paddle; forming a pad extension having a spacing to the package paddle; forming a lead adjacent the pad extension, the pad extension between the package paddle and the lead; forming a conductive layer directly on and between the package paddle and the pad extension; and connecting an integrated circuit to the pad extension and the lead, the integrated circuit over the package paddle.