3D Coil Interconnection for Stretchable Electronics
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Solution Overview
Problem
Existing stretchable electronic devices face limitations in stretchability, reliability, and manufacturing complexity due to restricted metal interconnection expansion, high electric resistance in conductive materials, and localized strain concentration in 2D spring-shaped interconnections.
Innovation Solution
A stretchable electronic device with a 3D coil interconnection and a method of manufacturing that includes forming coil interconnections on a substrate, covering them with a stretchable insulating layer, separating substrates, and forming transistors, using sacrificial layers and electroplating methods to create a zigzagged coil structure that distributes strain uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wave-shaped metal interconnection is used to provide stretchability, then the electronic device can be stretched, but the stretchability is restricted by the pre-strain amount and manufacturing processes become complex
Solution Approach 1:
The patent transitions from 2D wave-shaped interconnections to 3D coil-shaped interconnections. The coil structure extends into the vertical dimension, allowing the interconnection to accommodate larger strain while maintaining a compact footprint. This dimensional change enables greater stretchability without proportionally increasing manufacturing complexity, as the coil geometry can be formed through standard electroplating processes on pre-strained substrates.
2Adaptability or versatility
If conductive stretchable material is used instead of metal interconnection, then expandability increases, but electric resistance becomes higher
Solution Approach 1:
The patent employs a composite interconnection structure consisting of a metal core (such as copper or aluminum) coated with a stretchable conductive material or encapsulated in a stretchable insulating layer. This composite approach combines the low electrical resistance of metal with the high expandability of stretchable materials. The metal core provides excellent electrical conductivity while the surrounding stretchable material allows the interconnection to expand and contract with the substrate without breaking.
3Ease of manufacture
If 2D plane spring interconnection is used, then manufacturing costs reduce and reliability improves, but expanding rate is limited due to localized strain concentration
Solution Approach 1:
The patent transitions from 2D plane spring interconnections to 3D coil-shaped interconnections. The coil structure extends into the vertical dimension, distributing strain more uniformly throughout the volume of the interconnection. This dimensional change allows the interconnection to accommodate larger expansion rates without concentrating stress at specific points, thereby preventing damage while maintaining compatibility with standard manufacturing processes.
4Reliability
If metal interconnection is used, then conductivity is high, but stretchability is restricted by pre-strain amount
Solution Approach 1:
The patent employs a 3D coil geometry for metal interconnections, which allows the metal to accommodate larger strains through the coil's geometric deformation. The coil structure can expand and contract by changing its coil diameter and pitch, enabling the metal interconnection to achieve stretchability beyond the limitations of pre-strained flat substrates while maintaining continuous metal pathways for high conductivity.
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 3D coil interconnection design enhances stretchability, minimizes strain concentration, and simplifies manufacturing, providing a reliable and scalable solution for stretchable electronic devices.
Implementation Method 1
forming a first seed layer on the sacrificial layer; forming a first photoresist pattern on a part of the first seed layer; and forming a first cap interconnection layer on the first seed layer exposed by the first photoresist pattern
Data Source
AI summary
Provided are a stretchable electronic device and a method of manufacturing the same. The manufacturing method includes forming coil interconnection on a first substrate, forming a first stretchable insulating layer that covers the coil interconnection, forming a second substrate on the first stretchable insulating layer, separating the first substrate from the coiling interconnection and the first stretchable insulating layer, and forming a transistor on the coil interconnection.