Excimer Light Separation of Methacrylate Bonded Substrates

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Solution Overview

Problem

Conventional methods for separating bonded parts using adhesives often compromise adhesion reliability, particularly in terms of heat resistance, moisture resistance, and lightfastness, as they require exposure to heat or UV light, which weakens these properties and makes separation difficult in high humidity conditions.

Innovation Solution

The method involves using an acrylic adhesive with specific methacrylate components and irradiating the bonded parts with excimer light of a center wavelength between 1 to 300 nm, preferably 172 nm or 193 nm, to effectively separate substrates while maintaining superior heat resistance, moisture resistance, and lightfastness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional adhesives with high adhesion strength are used to secure components, then adhesion reliability is improved, but separation becomes difficult

Engineering Contradiction:
Improveadhesion reliabilityVSAvoidseparation ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The adhesive composition is designed with built-in separation functionality from the beginning. It contains photopolymerization initiators that remain dormant during normal adhesion operations but activate upon exposure to specific wavelength light (e.g., 365 nm UV light), enabling controlled separation without compromising initial adhesion strength. This preliminary design of dual functionality (adhesion + separation) resolves the contradiction between strong bonding and easy separation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The separation process is achieved by changing the physical parameter of light wavelength exposure. The adhesive maintains its adhesive properties under normal conditions but undergoes a fundamental change when exposed to specific wavelength light, which triggers photopolymerization reversal or degradation. This parameter change (light wavelength exposure) enables separation while maintaining adhesion reliability during normal operation.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If heat or UV light is used to separate bonded parts, then separation is achieved, but heat resistance and lightfastness are compromised

Engineering Contradiction:
Improveseparation easeVSAvoidheat resistance and lightfastness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

A specific wavelength light (e.g., 365 nm UV light) serves as an intermediary trigger for separation. This light wavelength is carefully selected to activate the photopolymerization initiators embedded in the adhesive without significantly affecting the heat resistance and lightfastness properties of the bonded parts. The intermediary light trigger enables separation while preserving the structural integrity and resistance properties of the bonded components.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The separation functionality is localized to the adhesive layer itself, which contains the photopolymerization initiators. The bulk bonded parts (optical lenses, prisms, semiconductor components) do not require special properties to resist separation, as only the adhesive responds to the light trigger. This local quality differentiation allows separation without compromising the heat resistance and lightfastness of the valuable bonded components.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If organic solvents or strong acid/alkali solutions are used to separate bonded parts, then separation is achieved, but environmental harm and health impacts increase

Engineering Contradiction:
Improveseparation easeVSAvoidenvironmental harm and health impacts
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The chemical separation methods (organic solvents, strong acids, alkalis) are replaced with a physical method using light energy. The photopolymerization initiators in the adhesive respond to specific wavelength light by undergoing photopolymerization reversal or degradation, enabling separation through light exposure rather than harsh chemicals. This substitution eliminates environmental harm and health impacts associated with chemical solvents while maintaining effective separation capability.

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

Solution Approach 2:

Instead of using strong acid or alkali solutions for separation, the invention employs photopolymerization initiators that undergo accelerated oxidation or degradation when exposed to specific wavelength light. This light-induced chemical change enables separation without requiring harmful chemical solvents, thereby eliminating environmental harm and health impacts while maintaining separation effectiveness.

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

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

This approach allows for easy separation of bonded parts with enhanced heat resistance, moisture resistance, and lightfastness, improving production yield in applications like optical lenses, prisms, and semiconductor packaging without sacrificing adhesion strength.

Implementation Method 1

the adhesive composition is applied between two elements, and the elements are firmly affixed to one another by irradiating the adhesive with light. By later stimulating the adhesive composition with light or heat, a gas is emitted from the gas generating agent

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

irradiating the bonded part with excimer light of a center wavelength between 1 to 300 nm, preferably 172 nm or 193 nm, to effectively separate substrates

Methodology Applied
Scientific EffectPhotodissociation: Photodissociation

Data Source

PatentUS8845858B2Method for separating bonded bodies using excimer light irradiation
Publication Date: 2014.09.30 DENKA CO LTD

AI summary

Disclosed is a method for separating a bonded body, whereby the bonded body can be separated easily. Specifically disclosed is a method for separating bonded bodies that includes a step that irradiates excimer light with a central wavelength of 1 to 300 nm on to a bonded body that has been formed by using an adhesive composition to bond substrates together, which includes and is formed by one type or two or more types of meth (acrylate) that have one or more (meth)acryloyl groups, and by hardening of said adhesive composition. At least one of the substrates is permeable to the excimer light.