Graphite Laminated Body with Thermoplastic Polyimide Adhesive

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Solution Overview

Problem

Graphite composite films used in electronic devices face issues with mechanical strength, heat dissipation, and durability, particularly when exposed to high temperatures, leading to electrical shorts, contamination, and reduced performance.

Innovation Solution

A graphite laminated body comprising a graphite film bonded with a non-thermoplastic polyimide film using a thermoplastic polyimide or fluororesin adhesive layer, which provides enhanced mechanical strength, heat resistance, and thermal conductivity, suitable for temperatures above 200°C.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If a graphite sheet is directly used as a thermally conductive material, then thermal conductivity is improved, but electrical conductivity causes short circuits between electronic components

Engineering Contradiction:

Improvethermal conductivityVSAvoidelectrical conductivity causing short circuits

Core Design Contradiction:

Use of energy by stationary objectVSObject-affected harmful factors

Solution Approach 1:

The graphite sheet is segmented into fine graphite powder particles that are dispersed and embedded within an insulating resin matrix. This segmentation maintains the thermal conductivity benefits of graphite while the resin insulation prevents electrical short circuits between components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An insulating resin material acts as an intermediary between the graphite particles and the electronic components. The resin provides electrical insulation to prevent short circuits while allowing thermal conduction through the embedded graphite particles.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by stationary object

If a graphite sheet is used, then thermal conductivity is improved, but surface wearing away creates carbon powder that disperses and electrically affects the device

Engineering Contradiction:

Improvethermal conductivityVSAvoidcarbon powder dispersion causing electrical effects

Core Design Contradiction:

Use of energy by stationary objectVSObject-generated harmful factors

Solution Approach 1:

A composite material structure is created where graphite powder is embedded within a resin matrix. This composite provides thermal conductivity from the graphite while the resin binding structure prevents surface wearing and carbon powder dispersion that would otherwise occur with pure graphite sheets.

Inventive Principle:

Principle #40Composite materials

3Object-affected harmful factors

If a graphite composite film with resin coating is used, then electrical conductivity issues are prevented, but repeated bending causes graphite film to lift from coating layer reducing heat dissipation

Engineering Contradiction:

Improveelectrical conductivity controlVSAvoidheat dissipation properties under repeated bending

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The adhesive properties of the resin are optimized by controlling its molecular weight and composition to maintain strong bonding between the graphite-containing layer and coating under repeated bending conditions. This parameter optimization prevents delamination while maintaining electrical insulation.

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If epoxy or acrylic adhesive is used for heat spreading sheet, then bonding is achieved, but adhesive deterioration at high temperature causes peeling off limiting usage to 200°C or less

Engineering Contradiction:

Improvebonding capabilityVSAvoidheat resistance above 200°C

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The adhesive resin is formulated with specific molecular weight parameters and chemical composition that provide both adequate bonding capability and high-temperature stability. By optimizing these parameters, the adhesive maintains its bonding strength at temperatures above 200°C where conventional epoxies and acrylics would deteriorate.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

A composite adhesive system is used where the resin matrix combines bonding agents with heat-resistant components. This composite adhesive structure provides both the manufacturing ease of adhesive bonding and the heat resistance required for high-temperature applications.

Inventive Principle:

Principle #40Composite materials

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 solution achieves excellent mechanical properties and thermal conductivity in the surface direction while maintaining heat dissipation capabilities, preventing issues like electrical shorts and contamination, and ensuring durability at high temperatures.

Implementation Method 1

an adhesive layer for bonding the graphite film to the non-thermoplastic polyimide film

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

a graphite film excellent in thermal conductivity in the surface direction

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10946617B2Graphite laminated body

Publication Date: 2021.03.16 PANASONIC HOLDINGS CORP

AI summary

Provided is a graphite laminated body having excellent properties such as excellent mechanical properties, excellent heat resistance, and excellent thermal conductivity. In particular, provided is a graphite laminated body comprising a graphite film, a non-thermoplastic polyimide film, and an adhesive layer for bonding the graphite film to the non-thermoplastic polyimide film, the adhesive layer being made of a thermoplastic polyimide or a fluororesin.