Stretchable Interconnection Geometry for Reliable Metallization
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Solution Overview
Problem
Existing stretchable electronic devices face issues with the reliability of stretchable interconnections, which can break when stretched beyond a certain limit, leading to reduced device lifetime and the need for zero-ohm cross-over resistors in single level metallization.
Innovation Solution
A stretchable electronic device with a double level interconnection system, where the electrically conductive channels and flexible supporting layers have distinct geometries to control and limit stretchability, avoiding the use of zero-ohm cross-over resistors by using a flexible insulating layer to separate and support the channels, and incorporating a second conductive layer for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single level metallization with stretchable interconnections is used, then the device can achieve flexibility and space savings, but the interconnections can break when stretched beyond a certain limit, reducing reliability
Solution Approach 1:
The patent transitions from a single-level metallization to a double-level metallization structure. The first electrically conductive channel is supported by a first flexible supporting layer, and the second electrically conductive channel is supported by a second flexible supporting layer, with the channels arranged in different planes. This dimensional separation allows each channel to be independently optimized for stretchability while maintaining overall structural integrity, thereby improving reliability without sacrificing flexibility.
Solution Approach 2:
The stretchable interconnection is divided into multiple independent conductive channels (first and second channels) supported by separate flexible supporting layers. Each channel can be independently designed with specific geometries and stretch characteristics. This segmentation allows the system to distribute mechanical stress across multiple independent paths, preventing single-point failures and improving overall reliability.
2Adaptability or versatility
If zero-ohm cross-over resistors are used in single level metallization to enable channel crossings, then the circuit design becomes possible, but the device complexity increases and additional components are required
Solution Approach 1:
The patent uses a double-level metallization structure where the first electrically conductive channel and second electrically conductive channel are arranged in different planes (levels). This spatial separation in the vertical dimension allows the channels to cross each other without electrical interference, eliminating the need for zero-ohm cross-over resistors. The flexible supporting layers provide the necessary mechanical support and isolation, enabling complex circuit designs with fewer components.
3Reliability
If the electrically conductive channel geometry is optimized for maximum stretchability, then the elastic limit is increased, but the channel may still break due to lack of geometric deviation control
Solution Approach 1:
The patent specifies that the first flexible supporting layer has a predetermined second geometry with a predetermined deviation from the first geometry of the electrically conductive channel. This local geometric deviation is intentionally introduced in specific regions to control and limit the stretchability of the channel. By adjusting the deviation parameters in different locations, the design optimizes stretchability in critical areas while maintaining geometric precision in other areas, achieving a balance between reliability and manufacturing precision.
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
The solution increases the reliability and lifetime of the electronic device by controlling stretchability, reducing the risk of overstretching and breaking, and allowing for more complex and compact circuit designs without the need for additional resistors, facilitating the integration of electronic components with improved soldering connections.
Implementation Method 1
an electrically conductive channel having a predetermined first geometry by which said channel is stretchable up to a given elastic limit and a first flexible supporting layer provided for supporting the electrically conductive channel and having a predetermined second geometry by which said first supporting layer is stretchable
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3(a)~3(h)
AI summary
A stretchable electronic device comprising a stretchable interconnection electrically connecting two electronic components, the stretchable interconnection comprising an electrically conductive channel having a predetermined first geometry by which said channel is stretchable up to a given elastic limit and a first flexible supporting layer provided for supporting the electrically conductive channel and having a predetermined second geometry by which said first supporting layer is stretchable. The predetermined second geometry has a predetermined deviation from the predetermined first geometry chosen for restricting stretchability of the electrically conductive channel below its elastic limit.