Non-Contacting Microwave Interlayer Interconnect for CTE Mismatch
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Solution Overview
Problem
Multilayer substrate circuit modules face issues with deformation and degradation of interlayer interconnects due to differences in coefficient of thermal expansion (CTE) when exposed to wide temperature ranges, leading to reliability and performance degradation.
Innovation Solution
The implementation of non-contacting microwave interlayer interconnects using a broadside coupler with conductive elements separated by a dielectric spacer, allowing for independent expansion and contraction of substrates without direct electrical contact, thereby maintaining electrical integrity across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plated-through holes are used for interlayer interconnects, then electrical connection between layers is achieved, but deformation and degradation occur due to CTE differences in wide temperature ranges
Solution Approach 1:
The patent removes the direct electrical connection through the substrate thickness by eliminating plated-through holes. Instead, it uses surface-mounted conductive elements that connect layers through electromagnetic coupling without penetrating the substrate, thereby extracting the source of thermal stress concentration at hole interfaces
Solution Approach 2:
The patent replaces the mechanical plated-through hole interconnect system with an electromagnetic field-based coupling system. Broadside couplers use electromagnetic induction to transfer signals between layers without physical contact through the substrate, substituting mechanical/electrical penetration with field-based interaction that is immune to CTE mismatch
2Stability of the object's composition
If CTE-matched materials are used for substrate layers, then thermal expansion compatibility is improved, but material selection freedom and optimization for specific electrical properties are reduced
Solution Approach 1:
The patent segments the interconnection function from the substrate structure by using separate surface-mounted conductive elements rather than integrated plated holes. This allows independent optimization of substrate materials for their respective electrical properties without being constrained by CTE matching requirements for mechanical interconnect integrity
Solution Approach 2:
By replacing mechanical plated-through interconnects with electromagnetic coupling between surface elements, the patent enables independent material selection for each substrate layer based on optimal electrical characteristics rather than thermal expansion compatibility, as the electromagnetic field coupling is not affected by substrate dimensional changes
3Reliability
If direct electrical contact through substrate layers is used, then interlayer connectivity is achieved, but signal loss and degradation occur due to contact points under thermal stress
Solution Approach 1:
The patent introduces an electromagnetic field as an intermediary between conductive elements on different layers, eliminating the need for direct physical contact through the substrate. The field couples the elements wirelessly across the dielectric, avoiding signal degradation at mechanical contact points while maintaining efficient energy transfer
Solution Approach 2:
The patent substitutes mechanical contact-based electrical interconnection with non-contact electromagnetic coupling. This eliminates resistive losses, contact resistance, and degradation at plated-hole interfaces, achieving lower insertion loss and higher signal integrity for microwave frequencies
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
This solution ensures reliable and efficient microwave signal coupling with low insertion loss over a wide frequency range, preventing degradation of interlayer interconnects and maintaining performance across extreme temperatures.
Implementation Method 1
couple a microwave signal from a first conductive element formed on a second side of the first substrate to a second conductive element formed on a third side of the second substrate
Implementation Method 2
The first substrate and the second substrate are separated and attached by a dielectric spacer
Data Source
AI summary
A circuit module may include a first substrate having a first side and a second side, a second substrate having a third side and a fourth side, the third side facing the second side, and a resilient bond layer coupling the second side to the third side. The first substrate may have a first coefficient of thermal expansion and the second substrate may have a second coefficient of thermal expansion substantially different from the first coefficient of thermal expansion. A broadside coupler may couple a microwave signal from the first substrate to the second substrate. The broadside coupler may include a first conductive element formed on the second side and a second conductive element formed on the third side proximate the first conductive element.