Thin Dual Foil Package for Flexible Electronics
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Solution Overview
Problem
Conventional SMD packages face challenges with increased pad count, reduced pad size, and distance, making electrical contacting difficult, especially in small spaces, and lack flexibility and reduced height, which complicates heat dissipation and signal transmission while being costly and inflexible.
Innovation Solution
A thin dual foil package is developed with two foil substrates and an electronic device in between, featuring electrically conductive layer structures and a casting compound, allowing for reduced thickness and flexibility, with conductive paths and pads that maintain compatibility with standard parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SMD packages are used with increased pad count and reduced pad size, then electrical contacting capability is improved, but package height is increased beyond 300 μm and flexibility is lost
Solution Approach 1:
The patent transitions from conventional three-dimensional SMD package structure to a two-dimensional thin foil structure. The package consists of two foil substrates with electronic devices arranged between them in a planar configuration, reducing the height dimension while maintaining electrical contacting capability through optimized pad and trace layouts on the foil surfaces.
Solution Approach 2:
The patent employs thin foil substrates instead of rigid package bodies. The foils have thicknesses of at most 130 μm each, providing inherent flexibility and enabling the package to be bent without damage. This thin film approach directly addresses the height reduction requirement while maintaining structural integrity for electrical connections.
2Length of stationary object
If package height is reduced to below 300 μm, then flexibility is improved, but manufacturing complexity increases due to fine-mechanical requirements
Solution Approach 1:
The patent divides the package into two separate foil substrates with distinct functions. The first foil substrate carries the electronic device and associated traces, while the second foil substrate provides the opposing structural layer. This segmentation allows each foil to be manufactured and prepared independently, reducing overall manufacturing complexity despite the thin dimensions.
Solution Approach 2:
The foil substrates serve multiple functions simultaneously: they provide mechanical support, electrical connectivity through traces and pads, thermal management pathways, and structural flexibility. This multi-functionality reduces the need for additional specialized components, simplifying the overall manufacturing process despite the reduced height constraints.
3Length of stationary object
If thin foil substrates with thickness less than 130 μm are used, then flexibility for bending is improved, but structural strength decreases
Solution Approach 1:
The foil substrates are constructed as composite structures combining multiple material layers. Each foil integrates metallic traces for electrical conductivity, polymeric or ceramic matrix materials for mechanical strength and flexibility, and functional coatings for protection and adhesion. This composite approach maintains structural strength despite the thin overall thickness of less than 130 μm.
Solution Approach 2:
The foil substrates exhibit different material properties at different locations to optimize both strength and flexibility. Areas requiring higher strength (such as regions with dense trace patterns or device mounting areas) have enhanced local reinforcement, while other areas maintain higher flexibility. This localized quality variation allows the thin foils to withstand mechanical stresses while preserving bendability.
Data Source
AI summary
A foil package includes a first foil substrate with a first and a second main surface, a second foil substrate with a first and a second main surface, wherein its first main surface is arranged facing the second main surface of the first foil substrate. The foil package includes at least one electronic device arranged between the first foil substrate and the second foil substrate and a first electrically conductive layer structure structured into a plurality of first partial areas arranged on the second main surface of the first foil substrate. The plurality of partial areas incompletely cover the second main surface of the first foil substrate. The at least one electronic device includes a terminal side and a side opposite to the terminal side.