3D Thermally Conductive Support for MMIC Heat Management
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Solution Overview
Problem
Existing cooling structures for Monolithic Microwave Integrated Circuits (MMICs) face challenges in efficiently managing heat while minimizing surface area usage and addressing thermal expansion mismatches, which can lead to mechanical strain and reduced performance.
Innovation Solution
A three-dimensional thermally conductive support structure with anisotropic heat conducting properties is used, featuring a heat spreader with basal planes that intersect the surface of heat-generating components, coupled with a conductive material providing a ground plane for microwave transmission lines and a heat sink, optimized for efficient heat transfer and reduced thermal-induced stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If diamond is used as a thermally conductive structure, then thermal conductivity is improved, but mechanical strain and thermal expansion mismatch occur
Solution Approach 1:
The patent uses a composite structure combining diamond with copper or aluminum, where diamond provides high thermal conductivity at the die interface and metal provides thermal expansion matching and mechanical compliance. This composite approach resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The patent modifies the thermal expansion parameters by introducing compliant layers and flexible thermal interface materials between the diamond and the die, allowing the system to accommodate thermal expansion differences while maintaining high thermal conductivity pathways.
2Reliability
If conventional cooling structures are used, then thermal expansion mismatch is reduced, but surface area consumption increases
Solution Approach 1:
The patent transitions from a planar cooling structure to a three-dimensional architecture with vertical thermal vias and stacked layers. This vertical integration allows heat to be conducted away through the thickness of the substrate rather than requiring large lateral surface area, thus reducing the footprint while maintaining effective heat dissipation.
Solution Approach 2:
The patent divides the cooling structure into multiple functional layers including thermal vias, intermediate thermal management layers, and heat sink structures. This segmentation allows each layer to be optimized for its specific function while collectively achieving high thermal conductivity with minimal surface area.
3Area of stationary object
If vertical thermal vias are used, then surface area is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent implements thermal vias only in specific locations where heat generation is highest, rather than uniformly throughout the substrate. This localized approach reduces the total number of vias required and simplifies manufacturing while still achieving effective heat management with reduced surface area.
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 effectively reduces the surface area required for MMICs, enhances heat dissipation, and improves mechanical reliability by matching Coefficients of Thermal Expansion (CTE) between components, thereby increasing the choice of thermally performing materials and reducing thermal-induced stresses.
Implementation Method 1
The PGS graphite has anisotropic heat conducting properties for conducing heat therethrough in the basal planes of the PGS graphite
Implementation Method 2
The PGS graphite has anisotropic heat conducting properties for conducing heat therethrough along directions parallel to the upper surface of the heat source and the bottom surface of the heat sink
Implementation Method 3
the MMIC is affixed (bonded) to a thermally conductive structure having a base/cold plate directly using a Thermal Interface Material (TIM), such as solder
Implementation Method 4
one technique used to cool electrical circuits, such as Monolithic Microwave Integrated Circuits (MMICs)
Data Source
Figure 1A~1C
Figure 1D
Figure 2A~2A'
AI summary
A MMIC support and cooling structure having a three-dimensional, thermally conductive support structure having a plurality of surfaces and a circuit having a plurality of heat generating electrical components disposed on a first portion of the surfaces and interconnected by microwave transmission lines disposed on a second portion of the plurality of surfaces of the thermally conductive support structure.