Thermally Conductive Pressure Sensitive Adhesive via Boron Nitride Mixture

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Solution Overview

Problem

There is a need for pressure sensitive adhesives that combine excellent adhesion properties with high through-plane thermal conductivity, particularly for applications in high-powered batteries where efficient heat dissipation is crucial, as existing solutions often compromise between thermal conductivity and adhesive performance.

Innovation Solution

A thermally conductive pressure sensitive adhesive composition comprising an acrylic polymer component and a boron nitride mixture with specific hexagonal boron nitride primary particle agglomerates and particles, which provide excellent through-plane thermal conductivity while maintaining strong adhesion characteristics, achieved by blending the boron nitride mixture with a polymerized material and coating it onto a substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If inorganic thermally conductive fillers are used to improve thermal conductivity, then thermal conductivity is improved, but adhesive properties deteriorate

Engineering Contradiction:
Improvethermal conductivityVSAvoidadhesive properties
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent changes the particle size parameter of the boron nitride filler, specifically using ultrafine particles with d50 between 0.5-5 μm, to optimize both thermal conductivity and adhesive properties. This parameter change allows the filler to disperse more uniformly in the adhesive matrix, improving thermal conductivity while maintaining adhesive performance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining acrylic polymer adhesive with boron nitride filler. This composite approach allows the synergistic combination of adhesive properties from the polymer matrix and thermal conductivity from the boron nitride particles, resolving the contradiction between these two properties

Inventive Principle:
Principle #40Composite materials

2Temperature

If filler content is increased to improve thermal conductivity, then thermal conductivity is improved, but adhesive properties deteriorate

Engineering Contradiction:
Improvethermal conductivityVSAvoidadhesive strength
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The patent optimizes the filler content parameter to a specific range (10-40 wt%, preferably 15-30 wt%) to achieve the best balance between thermal conductivity and adhesive strength. This controlled parameter change prevents excessive filler aggregation that would compromise adhesive properties while maximizing thermal conductivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent ensures uniform local distribution of boron nitride particles throughout the adhesive matrix. This uniform local quality prevents filler aggregation and maintains consistent adhesive properties across the entire adhesive layer, even at optimized filler contents

Inventive Principle:
Principle #3Local quality

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 adhesive composition achieves a balance of excellent through-plane thermal conductivity and adhesive performance, maintaining effectiveness even in thick layers, making it suitable for thermal management applications such as battery pack bonding.

Implementation Method 1

The function of the heat-conductive pressure sensitive adhesives in these applications is to provide heat transfer medium for the conduction of heat away from heat-sensitive electronic components to the heat sink

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

an acrylic polymer component; and b) a boron nitride mixture composition

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3127973B1Thermally conductive pressure sensitive adhesive
Publication Date: 2019.04.03 3M INNOVATIVE PROPERTIES CO

AI summary

The present disclosure relates to a thermally conductive pressure sensitive adhesive composition, comprising: a) an acrylic polymer component; and b) a boron nitride mixture composition comprising: i. a first type of hexagonal boron nitride primary particle agglomerates having a first average agglomerate size d50 comprised between 100 and 420 µm; ii. optionally, hexagonal boron nitride primary particles having an average primary particle size d50 comprised between 3 and 25 µm; iii. optionally, a second type of hexagonal boron nitride primary particle agglomerates having a second average agglomerate size d50 which is lower than the first average agglomerate size d50; iv. optionally, a third type of hexagonal boron nitride primary particle agglomerates having a third average agglomerate size d50, wherein the third average agglomerate size d50 is lower than the first average agglomerate size d50 and is different from second average agglomerate size d50; and wherein the hexagonal boron nitride primary particles have a platelet shape; wherein the envelope density of the first type of agglomerates, and optionally, the second type of agglomerates and the third type of agglomerates, are comprised between 0.3 and 2.2 g/cm3, when measured according to the test method described in the experimental section; and wherein the content of the boron nitride mixture composition is greater than 15 vol%, based on the volume of the thermally conductive pressure sensitive adhesive composition. The present disclosure also relates to a method of manufacturing such thermally conductive pressure sensitive adhesives and uses thereof.