Thermally Conductive Thermoplastic Compositions Using Expanded Graphite

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Solution Overview

Problem

Current thermally conductive thermoplastic compositions exhibit low thermal conductivity, which limits their effectiveness in applications such as LED heat sinks and other electronic devices.

Innovation Solution

A composition comprising 90 wt.-% to 30 wt.-% of an amorphous thermoplastic, preferably polycarbonate, combined with 10 wt.-% to 70 wt.-% of expanded graphite, where 90% of the graphite particles have a particle size of at least 200 microns, without polytetrafluoroethylene (PTFE) or potassium perfluorobutane sulphonate, enhancing thermal conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If thermally conductive fillers are added to thermoplastic resin, then thermal conductivity is improved, but mechanical stresses and CTE differentials worsen

Engineering Contradiction:

Improvethermal conductivityVSAvoidmechanical stresses

Core Design Contradiction:

TemperatureVSStress or pressure

Solution Approach 1:

The patent changes the particle size parameter of the graphite filler to at least 200 microns (coarse particles), which reduces the filler loading required to achieve target thermal conductivity, thereby reducing CTE differential and mechanical stresses in the composite

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material combining coarse graphite particles (≥200 microns) with thermoplastic resin, optimizing the balance between thermal conductivity and mechanical stress by using larger particles that create fewer stress concentration points

Inventive Principle:

Principle #40Composite materials

2Ease of operation

If graphite particle size is increased to reduce mechanical stresses, then ease of operation is improved, but manufacturing precision may worsen

Engineering Contradiction:

Improveease of moldingVSAvoidmolding precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent optimizes the particle size parameter to a specific range (at least 200 microns) that balances ease of molding with manufacturing precision, avoiding both fine particle difficulties and excessive coarse particle challenges

Inventive Principle:

Principle #35Parameter changes

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 high thermal conductivity and improved flammability ratings, making it suitable for demanding applications like LED heat sinks without introducing mechanical stresses or compromising dielectric properties.

Implementation Method 1

The composition achieves high thermal conductivity... combined with 10 wt.-% to 70 wt.-% of expanded graphite

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Expanded graphite has been known in the art for some time... describes ways of making expanded graphite

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2721111B1Thermally conductive thermoplastic compositions

Publication Date: 2019.05.15 THERMAL SOLUTION RESOURCES LLC

AI summary

The present invention provides a composition containing about 90% to about 30% of at least one amorphous thermoplastic or at least one semi crystalline thermoplastic or a mixture thereof and about 10% to about 70% of expanded graphite, wherein about 90% of the particles of the expanded graphite have a particle size of at least about 200 microns. The inventive compositions may find use in LED heat sink applications.