Laser Curing of Encapsulated Epoxy Resin for Electronics

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Solution Overview

Problem

Conventional resin composition curing methods face challenges such as long curing times, heat load on adherends, non-uniform performance, acid corrosion, and low durability in electronic components, particularly in methods involving one-part epoxy resins, two-part epoxy resins, UV-curable adhesives, and instant adhesives.

Innovation Solution

A resin composition curing method using an epoxy resin with an encapsulated curing agent, filler, and color material, where the resin composition is irradiated with laser light to achieve rapid curing at low temperatures, reducing heat load and ensuring stable bonding quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If one-part epoxy resin adhesive agent is cured by heating, then bonding strength is improved, but curing time is excessively long (approximately one hour) and heat load on adherend increases

Engineering Contradiction:
Improvebonding strengthVSAvoidcuring time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The curing agent is pre-encapsulated in microcapsules and mixed with the epoxy resin in advance. The microcapsules remain stable during storage and application, but rupture upon laser irradiation to release the curing agent and initiate rapid curing. This preliminary preparation enables instant curing activation without requiring advance mixing or long curing times.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces conventional thermal heating methods with laser irradiation to activate the curing process. The laser energy directly breaks the microcapsule walls and triggers the curing reaction, eliminating the need for prolonged thermal heating and significantly reducing curing time from one hour to seconds.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If one-part epoxy resin adhesive agent is cured by heating, then bonding strength is improved, but heat load on adherend and deformation increase

Engineering Contradiction:
Improvebonding strengthVSAvoidheat load and deformation
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent replaces conventional thermal heating with laser irradiation to initiate curing. The laser energy is absorbed by the microcapsules and converts to localized thermal energy only at the adhesive location, avoiding widespread heat distribution to the adherend. This substitution eliminates thermal deformation and heat load on sensitive electronic components.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The curing reaction is activated locally only at the adhesive application site through targeted laser irradiation. The microcapsules rupture locally where the laser beam strikes, releasing the curing agent only in the bonding zone. This localized activation prevents heat spread to surrounding areas and avoids thermal damage to the adherend.

Inventive Principle:
Principle #3Local quality

3Loss of time

If two-part epoxy resin adhesive agent is mixed and applied, then curing time is short, but uniform mixing is difficult and stable bonding quality cannot be obtained

Engineering Contradiction:
Improvecuring timeVSAvoidbonding quality uniformity
Core Design Contradiction:
Loss of timeVSManufacturing precision

Solution Approach 1:

The curing agent is segmented into microcapsules that are uniformly distributed throughout the epoxy resin matrix. This segmentation allows the curing agent to be pre-mixed without aggregation or separation issues. When laser irradiation occurs, the microcapsules rupture uniformly, ensuring consistent curing throughout the adhesive layer and achieving stable bonding quality.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The curing agent is pre-encapsulated and uniformly distributed in the resin before application. This preliminary encapsulation eliminates the need for on-site mixing of two parts, ensuring uniform distribution of curing agent throughout the adhesive. The uniform pre-mixed composition guarantees consistent bonding quality across all applications.

Inventive Principle:
Principle #10Preliminary action

4Loss of time

If UV-curable adhesive agent is used, then curing time is short and low temperature curing is achieved, but acid remains in resin causing corrosion of electronic components

Engineering Contradiction:
Improvecuring timeVSAvoidacid corrosion
Core Design Contradiction:
Loss of timeVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by using epoxy resin with amine-based curing agent instead of UV-curable adhesive systems. This parameter change eliminates the acid byproduct generation inherent in UV-curing chemistry. The resulting cured adhesive is free from corrosive acids, making it suitable for electronic component applications while maintaining short curing time through laser activation.

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 method enables efficient bonding or sealing of electronic components with high durability and reduced heat load, minimizing component retention and deformation, while maintaining a long work life and stability of the resin composition.

Implementation Method 1

irradiating a resin composition (A) with laser light directly and/or indirectly

Methodology Applied
Scientific EffectLaser heating: Laser

Implementation Method 2

the resin composition (A) containing (i) an epoxy resin, (ii) an encapsulated curing agent including a core that contains a curing agent and a shell that covers the core

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 3

curing can be carried out in a short time without placing a heat load on an adherend and a cured product having stable bonding quality can be obtained

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentEP3118237B1Method for curing resin composition
Publication Date: 2021.09.01 OMRON CORP
  • EP3118237B1 patent drawingFigure 1~3
  • EP3118237B1 patent drawingFigure 4~5
  • EP3118237B1 patent drawingFigure 6(a)~7(b)

AI summary

The present invention provides a method with which curing can be carried out in a short time without a heat load on an adherend and a cured product having stable quality can be obtained. The resin composition curing method in accordance with the present invention includes the step (a) of directly and/or indirectly irradiating, with laser light, a resin composition (A) which contains (i) an epoxy resin, (ii) an encapsulated curing agent including a core that contains a curing agent and a shell that covers the core, (iii) a filler, and (iv) a color material.