Epoxy Thiol Gap Filler Composition for Thermal Conductivity and Adhesion

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Solution Overview

Problem

Current curable compositions used as gap fillers in electronic applications face challenges in achieving high thermal conductivity while maintaining good adhesion, toughness, elongation at break, and hydrolytic stability, particularly due to high loadings of inorganic thermally conductive fillers, which adversely affect these properties.

Innovation Solution

A curable composition is formulated by blending an epoxy resin with a multifunctional thiol containing compound, incorporating an inorganic filler at least 40% by weight, which provides a balance of high thermal conductivity, bonding strength, and high elongation at break.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If high loading of inorganic thermally conductive fillers is used, then thermal conductivity is improved, but adhesion, toughness, elongation at break, and hydrolytic stability deteriorate

Engineering Contradiction:
Improvethermal conductivityVSAvoidadhesion and toughness
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters by introducing a multifunctional thiol curing agent with specific molecular weight and functionality ranges, and using an epoxy resin with hydrolytic stability. This chemical parameter optimization allows achieving high thermal conductivity (≥1.0 W/m·K) while maintaining good adhesion and toughness, resolving the contradiction between thermal performance and mechanical reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite curable composition combining epoxy resin, multifunctional thiol curing agent, and inorganic filler (40-90 wt%). The synergistic interaction between these components produces a material that simultaneously achieves high thermal conductivity, good adhesion, toughness, and hydrolytic stability, overcoming the limitations of simple filler loading

Inventive Principle:
Principle #40Composite materials

2Temperature

If high loading of inorganic fillers is used, then thermal conductivity is improved, but elongation at break deteriorates

Engineering Contradiction:
Improvethermal conductivityVSAvoidelongation at break
Core Design Contradiction:
TemperatureVSStability of the object's composition

Solution Approach 1:

The patent optimizes the molecular weight of the multifunctional thiol curing agent (500-5000 g/mol) and its functionality (2-6), creating a flexible polymer network that maintains chain mobility even with high filler content. This enables achieving thermal conductivity ≥1.0 W/m·K while preserving elongation at break ≥5%, resolving the contradiction between thermal performance and compositional stability

Inventive Principle:
Principle #35Parameter changes

3Temperature

If high loading of inorganic fillers is used, then thermal conductivity is improved, but bonding strength deteriorates

Engineering Contradiction:
Improvethermal conductivityVSAvoidbonding strength
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The multifunctional thiol curing agent acts as an intermediary between the epoxy resin and inorganic filler particles. Its molecular structure with multiple reactive groups enables it to crosslink with epoxy while also interacting with filler surfaces, creating strong interfacial adhesion. This mediator role allows achieving thermal conductivity ≥1.0 W/m·K while maintaining overlap shear adhesion ≥5 N/mm², resolving the contradiction between thermal performance and bonding strength

Inventive Principle:
Principle #24Intermediary (Mediator)

4Temperature

If high loading of inorganic fillers is used, then thermal conductivity is improved, but hydrolytic stability deteriorates

Engineering Contradiction:
Improvethermal conductivityVSAvoidhydrolytic stability
Core Design Contradiction:
TemperatureVSStability of the object's composition

Solution Approach 1:

The patent selects epoxy resin with inherent hydrolytic stability and combines it with a multifunctional thiol curing agent that forms a crosslinked network resistant to hydrolysis. This chemical composition optimization enables achieving thermal conductivity ≥1.0 W/m·K while maintaining hydrolytic stability, resolving the contradiction between thermal performance and chemical stability

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 a good balance of thermal conductivity, bonding strength, toughness, and hydrolytic stability, while accommodating fast curing profiles suitable for automated processing.

Implementation Method 1

a curable composition is provided. The composition includes a first part comprising an epoxy resin; and a second part comprising a multifunctional, functional thiol containing compound

Methodology Applied
Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 2

an inorganic filler present in an amount of at least 40 weight %, based on the total weight of the curable composition

Methodology Applied
Scientific EffectThermal Conduction: Conduction (thermal)

Data Source

PatentEP3947510B1Curable compositions, articles therefrom, and methods of making and using same
Publication Date: 2026.03.18 3M INNOVATIVE PROPERTIES CO
  • EP3947510B1 patent drawingFigure 1~2
  • EP3947510B1 patent drawingFigure 3
  • EP3947510B1 patent drawing

AI summary

A curable composition includes a first part comprising an epoxy resin; and a second part comprising a multifunctional, functional thiol containing compound. The curable composition further includes an inorganic filler present in an amount of at least 40 weight %, based on the total weight of the curable composition. The multifunctional, functional thiol containing compound comprises an ether in the backbone thereof.