3D Flex-Foil Package Structure for Ultra-Thin Flip-Chip Mounting
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Solution Overview
Problem
Conventional electronic device packages face challenges in reducing size while maintaining compatibility and flexibility, with existing technologies struggling to achieve ultra-thin profiles and high performance without increasing costs or complexity.
Innovation Solution
A foil-based package with an electrically conductive layer and an electronic device mounted using flip-chip technology, featuring a recessed design with offset foil portions and a casting compound to enclose the device, allowing for reduced thickness and flexibility while maintaining standardization compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional SMD or QFN packages are used, then compatibility with standardized parameters is maintained, but package height exceeds 300 μm and flexibility is lost
Solution Approach 1:
The patent transitions from a conventional planar package structure to a three-dimensional recessed structure. The foil substrate is deformed to create a recess that accommodates the electronic device, allowing the package height to be reduced below 300 μm while maintaining standardized terminal pad layouts for compatibility with existing mounting systems.
Solution Approach 2:
The patent employs a foil substrate instead of rigid traditional package materials. This flexible foil allows the package to achieve both reduced height and cylindrical curvature flexibility, while the recessed structure formed in the foil maintains the necessary mechanical support and electrical connectivity for standardized compatibility.
2Length of stationary object
If package height is reduced to below 300 μm, then flexibility is improved, but manufacturing complexity increases
Solution Approach 1:
The foil substrate is divided into functionally distinct regions: a first foil portion containing package terminal pads and a second foil portion containing the recess with the electronic device. This segmentation allows each region to be optimized independently while simplifying the overall manufacturing process through specialized tooling for each area.
Solution Approach 2:
The recess is pre-formed in the foil substrate before the electronic device is mounted. This preliminary structuring of the foil substrate enables subsequent assembly steps to be simpler and more precise, reducing overall manufacturing complexity despite the advanced three-dimensional structure.
3Quantity of substance
If the number of IC contact pads increases to several hundred, then integration density improves, but electrical contacting becomes increasingly difficult
Solution Approach 1:
The patent extracts the bonding complexity from the assembly process by using direct flip-chip mounting where the electronic device is bonded directly to the foil substrate without intermediate bond wires. This eliminates the need for precision wire bonding equipment and simplifies the electrical contacting process for high-density IC pads.
Solution Approach 2:
The foil substrate with its electrically conductive layer serves as an intermediary between the high-density IC pads and the package terminal pads. This intermediate structure provides a simplified bonding surface that facilitates electrical contacting of several hundred IC pads without requiring complex wire bonding infrastructure.
4Length of stationary object
If recessed structure with offset foil portions is implemented, then package height is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The offset between the first and second foil planes is pre-determined by the depth of the recess formed in the foil substrate. This preliminary structuring establishes the precise geometric relationship between different foil portions before device assembly, reducing the precision requirements for subsequent mounting operations.
Solution Approach 2:
The foil substrate exhibits different geometric properties in different regions: the first foil portion maintains a reference plane for terminal pad mounting, while the second foil portion is recessed to accommodate the electronic device. This local differentiation of geometric quality allows precise control of the offset relationship through localized deformation rather than requiring precision across the entire substrate.
Data Source
AI summary
A flexible foil-based package is disclosed which comprises at least one flexible foil substrate on which at least one electronic device is mounted in flip-chip mounting technology. The flexible foil substrate is bent so that a recess is created in which the electronic device is arranged. A casting compound is applied to cover the electronic device.