Adhesive Composition for Electrical Conduction
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Solution Overview
Problem
Anisotropic conductive films face challenges in bonding electrical elements due to narrower bump surface areas and increased short-circuit probabilities, as they struggle to trap conductive particles effectively in the longitudinal direction and facilitate conduction in the transverse direction, especially with finer pitches between bumps.
Innovation Solution
A novel adhesive composition comprising nitrile-butadiene rubber, acrylate oligomer, thermoplastic resin, organic peroxides, and a coupling agent, which provides cohesive force, peeling force, and storage stability, while allowing flexibility for use in flexible electric components and circuits, and includes a specific ratio of components to ensure optimal bonding and conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anisotropic conductive film is used for bonding electrical elements, then conduction in the longitudinal direction can be achieved, but the narrower bump surface areas become more difficult to trap conductive particles and the finer pitch between bumps increases the short-circuit probability
Solution Approach 1:
The patent changes the fundamental parameters of the adhesive system by using a different chemical composition (acrylic-based adhesive with specific molecular weight range of 200,000 to 600,000) and adding rubber components (5-20 parts by weight) to modify the physical properties. This allows the adhesive to maintain reliability at finer pitches by providing better particle trapping and reduced short-circuit risk through enhanced cohesive force and flexibility.
Solution Approach 2:
The patent creates a composite adhesive material by combining acrylic-based adhesive with rubber components (such as polybutadiene, styrene-butadiene rubber, or nitrile-butadiene rubber). This composite structure provides both the conduction capability needed for reliability and the mechanical properties (flexibility and cohesive force) needed to handle finer bump pitches without short-circuits.
2Strength
If adhesive composition provides strong bonding force, then bonding strength between electrical elements is improved, but flexibility for application on flexible electric components is reduced
Solution Approach 1:
The patent combines acrylic-based adhesive (providing strong bonding strength through cohesive force) with rubber components (providing flexibility and elasticity). The rubber content of 5-20 parts by weight creates a balanced composite that maintains both strong bonding and sufficient flexibility for application on flexible electric components and circuits.
Solution Approach 2:
The patent modifies the molecular weight parameter of the acrylic-based adhesive to be in the range of 200,000 to 600,000, which optimizes the balance between bonding strength and flexibility. This specific molecular weight range provides adequate cohesive force while maintaining the adaptability needed for flexible applications.
3Adaptability or versatility
If adhesive composition includes rubber components, then flexibility is improved, but storage stability may be compromised
Solution Approach 1:
The patent carefully controls the rubber content parameter within 5-20 parts by weight and selects specific rubber types (polybutadiene, styrene-butadiene rubber, or nitrile-butadiene rubber) with controlled molecular weights. This parameter optimization ensures sufficient flexibility while maintaining storage stability by preventing excessive softening or degradation during storage.
Solution Approach 2:
The patent applies rubber components selectively to provide local flexibility where needed while maintaining the overall structural integrity and storage stability of the adhesive composition. The rubber is distributed within the acrylic-based adhesive matrix to provide localized adaptability without compromising global stability.
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 effectively maintains bonding and conduction between electrical elements, offering good peeling force and storage stability, and can be applied in low-temperature bonding processes, such as COG and COF applications, with improved durability and resistance to high temperature and humidity.
Implementation Method 1
two organic peroxides with different one minute half-life from each other
Implementation Method 2
one organic peroxide has a higher one minute half-life temperature in the range of 130° C. to 140° C., and the other organic peroxide has a lower one minute half-life temperature in the range of 110° C. to 120° C.
Implementation Method 3
a coupling agent
Implementation Method 4
25 to 46 parts by weight of a nitrile-butadiene rubber with Monney viscosity in the range of 50 to 75 (ML1+4@100)
Data Source
AI summary
The invention provides an adhesive composition for conduction between electrical elements, comprising 25 to 46 parts by weight of nitrile-butadiene rubber with Mooney viscosity ranged from 50 to 75 (ML 1+4@100)° C., 25 to 45 parts by weight of acrylic oligomer, 16 to 32 parts by weight of thermoplastic resin, two organic peroxides having different one-minute half-life temperatures from each other, and a coupling agent. The thermoplastic resin is selected from the group consisting of phenoxy resin, poly(methyl)methacrylate copolymer, polystyrene copolymer and Novolak resin.