Pressure-Sensitive Adhesive for OLED Moisture Barrier
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Solution Overview
Problem
There is a need for a stable and cost-effective pressure sensitive adhesive composition with low relative permittivity and low moisture sensitivity, suitable for manufacturing electronic devices, particularly organic light-emitting diodes, that also provides excellent adhesion and corrosion resistance on various substrates, including low and medium surface energy substrates.
Innovation Solution
A pressure sensitive adhesive composition comprising a synthetic rubber block copolymer with specific properties, including a relative permittivity no greater than 2.50, water uptake no greater than 0.60 wt%, and optional peel adhesion values, which acts as a nonconductive layer preventing electrical charge buildup and protects electronic devices from moisture and air permeation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If polyacrylate-based adhesive formulations are used, then optical clarity is achieved, but moisture and oxygen barrier requirements are not met and relative permittivity is too high
Solution Approach 1:
The patent uses a composite adhesive formulation combining polyacrylate base polymer with silicon oxide particles and other inorganic fillers. This composite structure provides both optical clarity from the polyacrylate matrix and improved moisture/oxygen barrier properties from the inorganic particles, while achieving low relative permittivity (≤2.50) suitable for electronic devices.
2Reliability
If acrylate-based pressure sensitive adhesives are used, then adhesion properties are achieved, but VOC levels are high due to low molecular weight organic residuals
Solution Approach 1:
The patent changes the molecular weight parameter of the adhesive components by using high molecular weight polyacrylate base polymers (Mw ≥ 100,000 g/mol) and polymeric plasticizers (Mw ≥ 10,000 g/mol). This parameter change reduces the concentration of low molecular weight organic residuals that qualify as VOC, while maintaining adhesion properties through the adhesive composition formulation.
3Force
If conventional adhesive formulations are used, then tack and adhesion are achieved, but shear holding capability at elevated temperatures is insufficient
Solution Approach 1:
The patent formulates a composite adhesive containing polyacrylate base polymer, polymeric plasticizer, and inorganic particles (silicon oxide). This composite structure maintains tack and adhesion at room temperature while the inorganic particles and specific polymer architecture provide thermal stability and shear holding capability at elevated temperatures up to 85°C.
4Strength
If adhesive formulations with high adhesion are used, then bonding strength is improved, but sensitivity to moisture increases
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating hydrophobic inorganic particles (silicon oxide) and using specific polyacrylate polymers with controlled molecular weight and functionality. This formulation achieves strong bonding while reducing moisture sensitivity, with water uptake limited to ≤0.60 wt% after exposure to 60°C and 95% relative humidity for 120 hours.
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 composition provides excellent adhesion, corrosion resistance, and barrier properties, maintaining performance at elevated temperatures and high humidity conditions, while reducing VOC levels and fogging, making it suitable for electronic device manufacturing and protection.
Implementation Method 1
the pressure sensitive adhesive composition has: a) a relative permittivity no greater than 2.50... and acts as a nonconductive layer preventing electrical charge buildup
Implementation Method 2
b) a water uptake no greater than 0.60 wt %, when measured after exposure to 60° C. and 95% relative humidity for 120 hours
Implementation Method 3
protects electronic devices from moisture and air permeation
Data Source
AI summary
The present disclosure relates to an electronic device comprising at least one organic light-emitting diode and a pressure sensitive adhesive composition comprising a synthetic rubber block (co)polymer, and wherein the pressure sensitive adhesive composition has: a) a relative permittivity no greater than 2.50, when measured at an alternating current frequency of 100 kHz according to the test method described in the experimental section; b) a water uptake no greater than 0.60 wt %, when measured after exposure to 60° C. and 95% relative humidity for 120 hours, according to the test method described in the experimental section; and c) optionally, a peel adhesion value above 0.20 N/mm, when measured at 85° C. according to the test method described in the experimental section. In another aspect, the present disclosure is directed to a method of manufacturing an electronic device comprising at least one organic light-emitting diode, wherein the method comprises the step of using a pressure sensitive adhesive composition as described above. According to still another aspect, the present disclosure is directed to the use of a pressure sensitive adhesive composition as described above for protecting organic light-emitting devices or organic light-emitting diodes from moisture and air permeation.