Thermally Conductive Polymer Compositions with Magnesium Oxide
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Solution Overview
Problem
Thermally conductive polymer compositions for electronic devices face challenges in achieving high thermal conductivity, low Coefficient of Linear Thermal Expansion (CLTE), mechanical strength, and flowability while maintaining moisture resistance under high temperature and pressure conditions, as existing compositions often suffer from decreased performance in severe environments.
Innovation Solution
A thermally conductive polymer composition comprising 15-70 weight percent thermoplastic polymer, 20-60 weight percent highly moisture-resistant magnesium oxide, and 5-50 weight percent filler with an aspect ratio greater than 5, where the magnesium oxide exhibits less than 1% weight gain at 90°C and 90% RH for 100 hours, and the filler is processed with a coupling agent to enhance interfacial bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high filler loading is used to increase thermal conductivity and decrease CLTE, then thermal conductivity is improved, but flowability of polymer compositions deteriorates
Solution Approach 1:
The patent uses a composite filler system combining magnesium oxide particles with high aspect ratio fillers (graphite, boron nitride, or metal fibers) to achieve synergistic effects. The high aspect ratio fillers provide thermal conductivity pathways while the magnesium oxide matrix maintains processability, resolving the contradiction between thermal performance and flowability
Solution Approach 2:
The patent optimizes the aspect ratio parameter of fillers to be greater than 5, and controls magnesium oxide particle size distribution and surface treatment parameters. These parameter changes enable the composition to achieve high thermal conductivity while maintaining adequate flowability for molding processes
2Stability of the object's composition
If high filler loading is used to decrease CLTE, then CLTE is improved, but flowability of polymer compositions deteriorates
Solution Approach 1:
The combination of magnesium oxide with high aspect ratio fillers creates a composite structure where the anisotropic fillers provide CLTE matching in critical directions while the overall composite maintains processable rheology, resolving the contradiction between CLTE control and flowability
3Reliability
If magnesium oxide is used to improve moisture resistance, then moisture resistance is improved, but thermal conductivity may be insufficient
Solution Approach 1:
The patent creates a composite where magnesium oxide provides moisture resistance and thermal stability while high aspect ratio fillers (graphite, boron nitride, or metal fibers) provide enhanced thermal conductivity pathways, resolving the contradiction between moisture resistance and thermal conductivity
Solution Approach 2:
The filler system is segmented into different functional components: magnesium oxide for moisture resistance and thermal stability, and high aspect ratio fillers for thermal conductivity. This segmentation allows each component to optimize its specific function without compromising the other
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 composition achieves a thermal conductivity of at least 0.5 W/mK, maintains seal integrity, and provides mechanical strength and heat shock resistance, while maintaining flowability and moisture resistance, making it suitable for severe environments.
Implementation Method 1
wherein said (b) magnesium oxide has a weight gain by conditioning at 90° C., 90% RH for 100 hours of less than 1%
Implementation Method 2
wherein said polymer composition has a thermal conductivity of at least 0.5 W/mK
Data Source
AI summary
Thermally conductive polymer compositions comprising polymer, highly moisture resistant magnesium oxide, and filler having higher aspect ratio than 5. The compositions are particularly useful for metal/polymer hybrid parts.