Degradable Epoxy Conductive Adhesive with Recyclable Curing Agent
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Solution Overview
Problem
Conductive adhesives face challenges such as lower conductivity, thermal conductivity, conductive fatigue, limited current carrying capacity, and poor impact strength due to the use of conventional curing agents like dicyandiamide and aromatic amines, which are difficult to melt, dissolve, and recover, leading to high recovery costs and environmental concerns.
Innovation Solution
A degradable and recoverable epoxy conductive adhesive is developed using a recyclable epoxy resin curing agent with a specific molecular structure, allowing for degradation under normal pressure and mild conditions, improving shear strength and reducing recovery costs, and incorporating a conductive filler like graphene for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional curing agents (dicyandiamide, aromatic amines) are used to achieve high heat resistance and rigidity, then the conductive adhesive has sufficient thermal stability, but the cured product becomes difficult to melt, dissolve, and recover, leading to high recovery costs and environmental concerns
Solution Approach 1:
The patent changes the chemical parameters of the curing agent from conventional dicyandiamide or aromatic amines to a specific aliphatic amine curing agent with defined molecular structure (formula 1). This parameter change enables the cured epoxy resin to maintain heat resistance while becoming degradable under specific conditions (acidic environment at 60-80°C), thus resolving the contradiction between thermal stability and recoverability.
2Strength
If conventional curing agents are used to ensure structural rigidity and strength, then the conductive adhesive meets mechanical performance requirements, but the three-dimensional network structure formed is difficult to break down, resulting in complex processing steps and high costs for recovering precious metals and graphene
Solution Approach 1:
The patent modifies the chemical structure parameter of the curing agent to an aliphatic amine with specific molecular formula (1), which creates a cured product that maintains mechanical strength (shear strength ≥20 MPa) while introducing degradable bonds that can be broken under mild acidic conditions, thereby simplifying the recovery process and reducing complexity.
Solution Approach 2:
The patent employs a degradable curing agent system that allows the epoxy matrix to be intentionally designed as temporarily stable but ultimately degradable. This enables the precious metals and graphene to be easily recovered after use, treating the polymer matrix as a temporary carrier that can be discarded or regenerated, thus reducing overall system cost and complexity.
3Reliability
If the amount of conductive filler (silver, graphene) is increased to improve electrical conductivity, then the conductive adhesive achieves sufficient conductivity, but the viscosity increases and the mechanical properties such as impact strength and toughness deteriorate
Solution Approach 1:
The patent applies local quality modification by using graphene surface-modified metallic silver filler instead of conventional filler. The graphene coating on the silver particles provides localized conductive pathways while the polymer matrix maintains its mechanical integrity. This local enhancement of conductivity through surface modification allows lower overall filler content while maintaining electrical performance and preserving mechanical properties.
Solution Approach 2:
The patent employs a composite filler system combining metallic silver particles with graphene surface modification. This composite structure leverages the high electrical conductivity of silver and the surface-enhancing properties of graphene, achieving sufficient conductivity at lower filler loadings while the polymer matrix (epoxy resin with degradable curing agent) maintains toughness and impact strength.
4Object-affected harmful factors
If lead-free solder with high melting point (217°C) is used to meet environmental regulations, then the solder is environmentally friendly, but the processing temperature must be increased by 30-40°C above melting point, reducing integration, reliability and functionality of the printed circuit board and components
Solution Approach 1:
The patent creates an alternative bonding system (conductive adhesive) that copies the environmental benefits of lead-free solder while avoiding its high processing temperature requirement. The degradable epoxy conductive adhesive can be processed at lower temperatures (60-80°C degradation, bonding below 150°C), providing an environmentally friendly solution that preserves component integrity and reliability.
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 solution significantly increases the shear strength of the conductive adhesive, enhancing its reliability and lifetime while simplifying the recovery process, offering economic and environmental benefits by allowing for easy degradation and recycling.
Implementation Method 1
Curing agent has great effect on the use characteristics of the conductive adhesive, and the performance of the thermosetting polymer formed by curing and having a three-dimensional network structure
Implementation Method 2
the conductive filler provides conductive property
Implementation Method 3
The electron mobility thereof at room temperature is more than 15000 cm2/V·s, which is higher than that of carbon nanotubes or silicon crystals
Data Source
AI summary
The present invention provides a degradable and recyclable epoxy conductive adhesive, which comprises the following raw materials in percentage by weight: 15% to 30% of epoxy resin, 1% to 10% of a curing agent, 0.1% to 2% of a reaction diluent and 15% to 85% of a conductive filler, wherein the curing agent comprises a breakable molecular structure. According to the epoxy conductive adhesive of the present invention, after the epoxy resin in the conductive adhesive is cured by using the recyclable and degradable epoxy resin curing agent of a specific molecular structure, the conductive adhesive can be degraded in normal pressure, mild and specific conditions, the process is simple and the operation is convenient, no contamination is brought to the environment, the recycling cost is largely reduced, and the recycling of the conductive adhesive has enormous economic and environmental advantages. By using the recyclable and degradable epoxy resin curing agent of a specific molecular structure, the shear strength of the conductive adhesive is greatly increased, and the reliability and the service life of the conductive adhesive are largely improved.