Leadframe IC Packages with Dual Heat Spreader Caps
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Solution Overview
Problem
Commercially available leadframe packages exhibit poor thermal performance and inadequate electromagnetic interference (EMI) shielding, leading to increased susceptibility and emission of EMI, which can cause logic failures and interference in integrated circuit (IC) devices.
Innovation Solution
The implementation of a leadframe IC package design that incorporates first and second heat spreader caps forming an enclosure structure with the leadframe, which includes a die attach pad, leads, and tie bars, to enhance thermal dissipation and EMI shielding. The caps are coupled to the leadframe using thermally and electrically conductive materials, forming a Faraday Cage-like structure to enclose the IC die and provide improved structural integrity and environmental protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional leadframe packages are used, then the structure is simple and manufacturing is easy, but thermal performance is poor and EMI shielding is inadequate
Solution Approach 1:
The patent merges multiple functions into the heat spreader caps: thermal dissipation, EMI shielding, and structural enclosure. The caps are made of thermally and electrically conductive materials that simultaneously perform heat spreading and form a Faraday Cage-like structure for EMI shielding, eliminating the need for separate thermal and EMI protection components.
Solution Approach 2:
The heat spreader caps serve multiple functions: they act as thermal pathways to dissipate heat from the IC die, form an enclosure structure to shield against EMI, provide mechanical support, and protect the internal components from environmental factors. This multi-functionality resolves the contradiction by improving reliability without proportionally increasing complexity.
2Temperature
If heat spreader caps are added to improve thermal performance, then thermal dissipation improves, but device complexity increases
Solution Approach 1:
The heat spreader caps combine thermal management and EMI shielding functions into a single component structure. The caps are positioned to directly contact or closely approach the IC die for efficient heat transfer, while simultaneously forming an enclosed structure with the leadframe that provides EMI shielding without requiring additional separate components.
3Object-affected harmful factors
If an enclosure structure is formed to provide EMI shielding, then EMI susceptibility and emission are reduced, but manufacturing complexity increases
Solution Approach 1:
The enclosure structure is segmented into modular components: the leadframe forms the base structure and one side of the enclosure, while the heat spreader caps form the top and/or bottom covers. This segmentation allows each component to be manufactured independently using standard processes, then assembled together, simplifying the overall manufacturing process compared to forming a complete enclosure as a single piece.
Solution Approach 2:
The heat spreader caps are designed to be attached to the leadframe in a preliminary assembly step before final packaging. The caps are positioned and secured to form the enclosure structure, which then serves as the foundation for subsequent assembly steps such as die attachment and wire bonding, streamlining the overall manufacturing process.
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 design significantly improves thermal performance and EMI shielding, reducing the risk of logic failures and interference by effectively dissipating heat and shielding EMI, while also enhancing structural rigidity and environmental protection against mechanical stress and corrosion.
Implementation Method 1
The first and second caps and the leadframe form an enclosure structure that substantially encloses the IC die(s)... The enclosure structure spreads heat from the IC die(s) during operation
Implementation Method 2
The first and second caps and the leadframe form an enclosure structure that substantially encloses the IC die(s)... the enclosure structure shields EMI emanating from the IC die(s) and EMI radiating toward the IC die(s) from outside the package
Data Source
AI summary
Methods and apparatus for improved thermal performance and electromagnetic interference (EMI) shielding in integrated circuit (IC) packages is described. A die-up or die-down package includes first and second caps defining a cavity, an IC die, and a leadframe. The leadframe includes a centrally located die attach pad, a plurality of leads, and a plurality of tie bars that couple the die attach pad to the leads. The IC die is mounted to the die attach pad. Planar rim portions of the first and second caps that surround the cavity are coupled to the leadframe. The first and second caps and the leadframe form an enclosure structure that substantially encloses the IC die, and shields EMI emanating from and radiating towards the IC die. The enclosure structure also dissipates heat generated by the IC die during operation.