Conformal Thermal Gap Filler Assembly for Shear-Resistant POM Cooling
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Solution Overview
Problem
Conventional thermal gap fillers in pluggable optical module (POM) heatsinks suffer from high thermal resistance due to micro-scale gaps between the POM and heatsink surfaces, which are not effectively addressed by existing solutions like thermal gap pads and thermal interface materials, which are prone to compression and shear forces, and polymer laminate of a polymer and a phase-change material to the heatsink base, with phase-change material transitioning to conform to the interstitial space when the POM becomes warm and the polymer allowing the surfaces to slide against one another over multiple POM insertion-removal cycles.
Innovation Solution
A shear resistant conformal thermal gap filler assembly is introduced, comprising a compressible material layer of aligned graphite or similar, covered by a shear resistant bearing surface with slits or openings, which flexes to conform to the POM surface, reducing thermal resistance by filling air gaps and enhancing thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal gap pad is placed between the POM contact surface and the heatsink base, then thermal contact resistance is reduced, but the gap pad becomes thick and prone to compression set
Solution Approach 1:
The thermal gap filler is segmented into multiple functional layers: a compressible base layer (0.5-1 mm thick) that fills gaps and absorbs compression, and a thin slotted metallic bearing surface layer that provides shear resistance. This segmentation allows each layer to specialize in one function, preventing the single-layer compression set problem while maintaining thermal contact.
Solution Approach 2:
The invention uses a composite structure combining a compressible material (such as aligned graphite or elastomer) with a thin metallic bearing surface. This composite material combines the gap-filling and compression-absorbing properties of the soft material with the shear strength and thermal conductivity of the metal, resolving the contradiction between compliance and structural stability.
2Reliability
If a thin compliant thermal interface material is applied to the heatsink base, then thermal contact resistance is reduced, but the TIM fails to fully close all gaps
Solution Approach 1:
The invention changes the thickness parameter of the compressible material to 0.5-1 mm, which is thicker than conventional TIM but thinner than traditional gap pads. This intermediate thickness, combined with the material's compressibility, allows it to deform and fill irregularities in the mating surfaces, achieving complete gap closure while maintaining thermal performance.
3Shape
If a laminate of polymer and phase-change material is applied to the heatsink base, then conformality is improved, but the polymer allows excessive surface sliding during POM insertion-removal cycles
Solution Approach 1:
The thermal gap filler is segmented into multiple functional layers: a compressible base layer (0.5-1 mm thick) that fills gaps and absorbs compression, and a thin slotted metallic bearing surface layer that provides shear resistance. This segmentation allows each layer to specialize in one function, preventing the single-layer compression set problem while maintaining thermal contact.
Solution Approach 2:
The thin slotted metallic bearing surface acts as a flexible yet strong film that conforms to the POM contact surface while resisting shear forces. The slots in the metallic layer provide flexibility for conformality while the metal material itself provides the shear strength that the polymer laminate lacked.
4Shape
If the bearing surface is made thin and flexible to conform to the POM surface, then conformality is improved, but the bearing surface becomes vulnerable to shear damage
Solution Approach 1:
The thin slotted metallic bearing surface acts as a flexible yet strong film that conforms to the POM contact surface while resisting shear forces. The slots in the metallic layer provide flexibility for conformality while the metal material itself provides the shear strength that the polymer laminate lacked.
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 assembly significantly reduces thermal resistance, enabling efficient cooling of high-power POMs, allowing air-cooling or liquid-cooling where previously not feasible, by eliminating most air gaps and maintaining structural integrity during POM insertion and removal.
Implementation Method 1
a 0.5-1 mm thick layer of aligned graphite or the like that is thermally conductive (10-80 W/mK) and (elastically) rebounds with limited compression set
Implementation Method 2
thermally conductive compressible material layer... thermally conductive shear resistant bearing surface... reduces thermal resistance by filling air gaps and enhancing thermal conductivity
Implementation Method 3
a thin slotted metallic structure or the like that adequately flexes and conforms to the POM contact surface and the compressible material
Data Source
AI summary
A shear resistant conformal thermal gap filler assembly for a circuit pack including a heatsink base collocated with an opening in a cage adapted to receive a pluggable optical module, a thermally conductive compressible material layer disposed on the heatsink base, and a thermally conductive shear resistant bearing surface disposed adjacent to the thermally conductive compressible material layer opposite the heatsink base, where the thermally conductive shear resistant bearing surface is adapted to contact a surface of the pluggable optical module through the opening in the cage when the pluggable optical module is received within the cage, and where the thermally conductive compressible material layer and the thermally conductive shear resistant bearing surface are adapted to conform to deviations in the surface of the pluggable optical module.