Compliant Micro-Coaxial Interconnects for High-Speed Photonic Systems
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Solution Overview
Problem
High-speed interconnects between substrates with differing thermal expansion coefficients, such as silicon and Lithium Niobate, face challenges with parasitic limitations and high fabrication costs due to the need for interposer layers and individual wire bonds, which impact bandwidth and performance in photonic systems.
Innovation Solution
A compliant micro-coaxial interconnect is formed with a cantilevered end portion and angled joints to minimize mechanical stress and facilitate movement between substrates, using a semiconductor lithography process to create a structure with an elongate conductive shield, core, and dielectric straps, allowing for efficient electrical coupling and reduced stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If interposer layers and wire bonds are used to connect substrates with differing CTE, then mechanical compliance is improved, but bandwidth and performance deteriorate due to parasitic effects
Solution Approach 1:
The patent removes the interposer layer from the interconnect structure, directly connecting the coaxial cable to the substrate. This extraction eliminates the parasitic effects introduced by the interposer while maintaining mechanical compliance through the flexible coaxial cable itself, thereby resolving the contradiction between mechanical compliance and bandwidth performance.
Solution Approach 2:
The patent employs a flexible coaxial cable with a compliant structure that can accommodate thermal expansion differences between substrates. The flexible nature of the coaxial cable provides mechanical compliance without requiring rigid interposer layers, thus maintaining both mechanical compliance and high bandwidth performance by avoiding parasitic effects.
2Stability of the object's composition
If interposer layers and individual wire bonds are used, then mechanical compliance is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent eliminates the interposer layer and complex wire bonding process by using a direct coaxial cable connection. This simplifies the manufacturing process significantly, reducing both the number of fabrication steps and the overall device complexity while maintaining mechanical compliance through the flexible cable design.
Solution Approach 2:
The patent combines the functions of mechanical support, electrical connection, and thermal compliance into a single coaxial cable structure. This merging of functions eliminates the need for separate interposer layers and wire bonds, thereby reducing fabrication complexity and manufacturing cost while maintaining mechanical compliance.
3Reliability
If rigid interconnect structures are used between substrates with differing CTE, then electrical continuity is maintained, but mechanical stress and breakage risk increase
Solution Approach 1:
The patent uses a flexible coaxial cable structure that can bend and deform to accommodate thermal expansion differences between substrates. This flexibility allows the interconnect to maintain electrical continuity while absorbing mechanical stress, thereby preventing breakage and improving reliability under thermal cycling conditions.
Solution Approach 2:
The patent employs a dynamic, flexible coaxial cable structure that can adapt its shape and position in response to thermal expansion forces. This dynamic compliance allows the interconnect to maintain electrical continuity while accommodating mechanical stress, resolving the contradiction between electrical continuity and mechanical stress resistance.
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 enables high-speed data transfer with reduced parasitic losses and dispersion, supporting bandwidths over 100 Gb/s while lowering production costs and maintaining electrical continuity across temperature changes.
Implementation Method 1
The cantilevered end portion has a first angled joint so that a pushing force and a pulling force applied thereby to the first coupler is minimized when mismatching movements of the first and second substrates occur
Implementation Method 2
using a first coupler (e.g., solder or a conductive adhesive) to electrically couple the cantilevered end portion to a second substrate
Implementation Method 3
a plurality of dielectric straps suspending the elongate conductive core within the elongate conductive shield
Data Source
AI summary
Systems (100) and methods (900) for providing a compliant micro-coaxial interconnect with an integrated circuit or other electronic device. The methods comprise: forming a well (108) in a first substrate (102) having a first Coefficient of Thermal Expansion (“CTE”); forming at least one three-dimensional micro-coaxial interconnect (100) on the first substrate so as to have a cantilevered end portion (110) disposed over the well; and using a first coupler (606) to electrically couple the cantilevered end portion to a second substrate (604) having a second CTE different from the first CTE. The cantilevered end portion has an angled joint (302) so that at least one of a pushing force and a pulling force applied thereby to the first coupler is minimized when mismatching movements of the first and second substrates occur.