IC Packaging Lead Conductive Cap for Reliability
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Solution Overview
Problem
Current integrated circuit packaging technologies face challenges in achieving increased lead density and structural integrity while maintaining a compact package size, which is essential for portable electronic devices, and existing solutions are not scalable or reliable enough to meet these demands.
Innovation Solution
The method involves forming a package paddle and a lead with a conductive cap composed of a nickel layer (2.55 μm to 8.00 μm thick), a palladium layer, and a gold layer, mounting an integrated circuit, attaching an electrical connector, and encapsulating the components to enhance structural integrity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional leadframe packaging is used, then manufacturing simplicity is maintained, but lead density and package size reduction are limited
Solution Approach 1:
The leadframe is segmented into a reusable support frame and disposable lead portions. The support frame retains the structural functions while the leads are separated as consumable elements that are attached to the integrated circuit and then discarded after serving their electrical connection purpose. This segmentation enables higher lead density by allowing leads to be optimized for electrical connection rather than structural support.
Solution Approach 2:
The disposable leads are extracted as a separate component from the traditional integrated leadframe structure. These leads are attached to the integrated circuit separately and then removed from the final package, leaving only the reusable support frame. This extraction allows for increased lead density while simplifying the permanent package structure.
2Area of stationary object
If lead density is increased to reduce package footprint, then package size is reduced, but structural integrity and reliability deteriorate
Solution Approach 1:
Different parts of the packaging system are assigned different qualities and functions. The support frame is designed with high structural integrity for mechanical support and surface mounting, while the disposable leads are optimized for electrical connection with appropriate conductivity and bonding characteristics. This local differentiation allows the package to achieve both small footprint and high reliability.
Solution Approach 2:
The packaging system uses a composite structure combining a permanent support frame material (optimized for mechanical strength) with disposable lead materials (optimized for electrical connection). This composite approach allows each component to be made from materials best suited for its specific function, achieving both compact size and high reliability.
3Volume of moving object
If package size is reduced for portable devices, then compactness is improved, but structural integrity and surface mounting capability worsen
Solution Approach 1:
The packaging system is segmented into a permanent support frame that provides structural integrity and disposable leads that provide electrical connection. This segmentation allows the support frame to be optimized for mechanical strength and surface mounting while the leads are optimized for electrical performance, enabling compact packaging without sacrificing structural integrity.
Solution Approach 2:
The support frame serves multiple functions: providing structural support for the integrated circuit, enabling surface mounting to the PCB, and serving as a permanent mechanical anchor. This multi-functionality allows the package to maintain structural integrity and mounting capability in a compact form factor.
4Reliability
If conventional nickel plating thickness is used, then manufacturing cost is reduced, but reliability in cyclic bending and thermal cycling deteriorates
Solution Approach 1:
The nickel plating thickness parameter is changed from conventional thin layers to a substantially uniform thickness of at least 2.55 μm. This parameter change significantly improves reliability in cyclic bending and thermal cycling tests while maintaining manufacturability through standardized plating processes. The increased thickness provides better corrosion resistance and mechanical durability.
Solution Approach 2:
The lead conductive cap uses a composite material structure with multiple layers (nickel, palladium, gold) where each layer provides specific functions. The nickel layer provides structural integrity and corrosion resistance, while the palladium and gold layers provide enhanced conductivity and surface properties. This composite structure achieves superior reliability while remaining manufacturable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves board-level reliability, with a 40% increase in cyclic bending performance and doubled reliability in thermal cycling tests, allowing the packaging system to withstand 30 drop tests without failure, compared to prior art systems that fail after the first drop.
Implementation Method 1
a nickel layer having a thickness between 2.55 μm to 8.00 μm deposited on the lead
Implementation Method 2
a palladium layer deposited on the nickel layer
Implementation Method 3
a gold layer deposited on the palladium layer
Data Source
AI summary
A method of manufacture of an integrated circuit packaging system includes: forming a package paddle; forming a lead adjacent to the package paddle; depositing a lead conductive cap on the lead, the lead conductive cap includes a nickel layer having a thickness between 2.55 μm to 8.00 μm deposited on the lead, a palladium layer deposited on the nickel layer, and a gold layer deposited on the palladium layer; mounting an integrated circuit over the package paddle; attaching an electrical connector between the lead conductive cap and the integrated circuit; and forming an encapsulation over the integrated circuit, a portion of the lead, and a portion of the package paddle.