Heat Dissipation Sheet Gradient Particle Distribution

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Solution Overview

Problem

Conventional thermally conductive sheets containing boron nitride face challenges in enhancing both thermal conduction and adhesiveness, leading to issues with void generation, reduced insulation properties, and peeling of circuit patterns, which compromises long-term insulation reliability.

Innovation Solution

A heat dissipation sheet comprising first inorganic particles with an average aspect ratio of 2 or less and second inorganic particles with an average aspect ratio greater than 2, along with a binder resin, is designed with specific volume content gradients to enhance adhesiveness and thermal conductivity, utilizing boron nitride as the second inorganic particle to improve orientation and thermal conduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hexagonal boron nitride particles are used to improve thermal conductivity, then thermal conduction is enhanced, but adhesiveness deteriorates due to particle orientation and peeling

Engineering Contradiction:

Improvethermal conductionVSAvoidadhesiveness

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent changes the aspect ratio parameter of inorganic particles from high (hexagonal boron nitride with aspect ratio > 2) to low (aspect ratio ≤ 2). This parameter change transforms the particle shape from scaly to spherical or slightly elongated, which fundamentally alters both thermal conduction behavior and adhesiveness. The spherical particles provide excellent adhesion to copper circuits while still enabling effective thermal conduction through the resin matrix.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining spherical inorganic particles (alumina, aluminum nitride, or silicon carbide) with a resin matrix. This composite approach allows optimization of both thermal conduction and adhesiveness by selecting appropriate particle materials and controlling their distribution, avoiding the peeling issues associated with pure hexagonal boron nitride while maintaining high thermal performance.

Inventive Principle:

Principle #40Composite materials

2Reliability

If ceramic substrate is used for heat dissipation, then thermal conduction is improved, but processability and multilayer formation deteriorate

Engineering Contradiction:

Improveheat dissipation performanceVSAvoidprocessability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material state from rigid ceramic substrate to flexible resin composite. This parameter change in material flexibility enables the heat dissipation sheet to be easily processed, cut, bent, and integrated into multilayer structures without the complex machining and joining processes required for ceramic substrates.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive ceramic substrates with a more cost-effective resin-based composite material. The resin matrix with inorganic particles provides adequate thermal conduction at lower material cost and processing cost, making the heat dissipation solution more economically viable for mass production.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If copper circuit is mounted on ceramic substrate, then electrical conduction is improved, but reliability deteriorates due to thermal expansion mismatch causing peeling

Engineering Contradiction:

Improveelectrical conductionVSAvoidthermal expansion compatibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the linear expansion coefficient parameter of the heat dissipation material by using resin matrix with inorganic particles instead of ceramic. The resin-based composite has a lower linear expansion coefficient that is closer to copper, reducing thermal stress during temperature cycling and preventing circuit peeling while maintaining electrical conduction pathways.

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 proposed configuration effectively enhances adhesiveness and long-term insulation reliability by controlling the orientation of inorganic particles, reducing peeling, and improving thermal conduction, thereby addressing the limitations of conventional sheets.

Implementation Method 1

a heat dissipation sheet containing first inorganic particles having an average aspect ratio of 2 or less, second inorganic particles having an average aspect ratio of more than 2, and a binder resin

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11492528B2Heat dissipation sheet, method for producing heat dissipation sheet, and laminate

Publication Date: 2022.11.08 SEKISUI CHEMICAL CO LTD

AI summary

Provided is a heat dissipation sheet capable of effectively enhancing adhesiveness and long-term insulation reliability. The heat dissipation sheet according to the present invention contains first inorganic particles having an aspect ratio of 2 or less, second inorganic particles having an aspect ratio of more than 2, and a binder resin. In this heat dissipation sheet, a content of the second inorganic particles is larger than a content of the first inorganic particles in 100% by volume of a region having a thickness of 15% on a first surface side in a thickness direction, and the content of the first inorganic particles in 100% by volume of the region having a thickness of 15% is larger than the content of the first inorganic particles in 100% by volume of a central region having a thickness of 70%.