Encapsulation Adhesive for Optoelectronic Barrier Performance

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Solution Overview

Problem

Current adhesive solutions for encapsulating (opto)electronic arrangements are inadequate in providing a robust barrier against oxygen and water vapor, leading to degradation of sensitive components like OLEDs and solar cells, and they often require complex application processes and high temperatures, which can damage the structures.

Innovation Solution

A pressure-sensitive adhesive composition comprising copolymers with isobutylene or butylene, hydrogenated adhesive resins, and reactive cyclic ethers, which can be crosslinked using photoinitiators for cationic curing, offering improved flexibility, adhesion, and transparency while maintaining a low permeability to oxygen and water vapor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If glass or metal substrates are used for encapsulation, then permeation barrier performance is improved, but mechanical stress resistance deteriorates and assembly thickness increases

Engineering Contradiction:
Improvepermeation barrier performanceVSAvoidmechanical stress resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent uses flexible polymer foils as encapsulation substrates instead of rigid glass or metal substrates. These flexible foils provide the necessary permeation barrier performance while being resistant to mechanical stress and enabling thin, lightweight assemblies that can bend and flex without damage.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent employs composite adhesive compositions combining multiple polymer components (polyisobutylene, polybutylene, and other copolymers) with specific molecular weights and compositions to achieve both barrier performance and mechanical flexibility in a single integrated material system.

Inventive Principle:
Principle #40Composite materials

2Reliability

If complex adhesive application processes are used, then adhesion performance is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveadhesion performanceVSAvoidapplication process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The adhesive composition is designed to self-adhere to the substrate surfaces upon application without requiring complex activation steps. The specific polymer composition provides inherent tack and bonding capability that simplifies the application process while maintaining strong adhesion performance.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent optimizes the molecular weight and composition parameters of the adhesive polymers to achieve the desired balance between adhesion performance and processability, allowing for simple application methods while maintaining reliable bonding.

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 adhesive provides a strong barrier against oxygen and water vapor, ensuring the longevity of (opto)electronic components, is easy to apply, and can be processed at lower temperatures, reducing the risk of damage to the electronic structures while maintaining high transparency and flexibility.

Implementation Method 1

at least one type of photoinitiator for initiating cationic curing

Methodology Applied
Scientific EffectPhotopolymerisation: Photopolymerisation

Implementation Method 2

maintaining a low permeability to oxygen and water vapor

Methodology Applied
Scientific EffectPermeation: Permeation

Data Source

PatentEP2768919B1Adhesive substance, in particular for encapsulating an electronic assembly
Publication Date: 2015.08.05 TESA SE
  • EP2768919B1 patent drawingFigure 1~2
  • EP2768919B1 patent drawingFigure 3~4
  • EP2768919B1 patent drawing

AI summary

The invention relates to an adhesive substance, in particular for encapsulating an electronic assembly against permeates, said substance comprising: (a) at least one copolymer containing at least isobutene or butene as comonomer types and at least one comonomer type which, when regarded as a hypothetical homopolymer, has a softening temperature greater than 40°C; (b) at least one type of an at least partially hydrogenated adhesive resin; (c) at least one cyclic ether-based type of reactive resin with a softening temperature less than 40 °C, preferably less than 20°C; and (d) at least one type of photoinitiator for initiating cationic curing.