Electrical Insulating Resin Composition for Circuit Boards
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Solution Overview
Problem
Existing electrical insulating materials for circuit boards face challenges in achieving a balance between flexibility, adhesiveness, thermal resistance, and durability under harsh environments, particularly high temperatures and humidity, due to limitations in epoxy resin compositions that compromise thermal conductivity and dielectric strength when filled with inorganic fillers.
Innovation Solution
An electrical insulating resin composition is developed, comprising a copolymer of aromatic vinyl and conjugated diene compounds, a polymerizable monomer with terminal reactive double bonds, and an oligomer with a ring structure, which undergoes radical polymerization to form a crosslinked structure, enhancing thermal resistance and adhesiveness while maintaining flexibility, and optionally includes a partially hydrogenated rubber-like polymer for improved oxidative stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the ratio of inorganic filler is increased to enhance thermal conductivity, then thermal conductivity is improved, but flexibility is reduced and the layer becomes fragile
Solution Approach 1:
The patent uses a composite resin system combining epoxy resin with flexible curing agents (polyetheramine, polyamide, or amino resin) to create a multi-phase composite structure. This composite approach allows the material to simultaneously achieve thermal conductivity enhancement through inorganic fillers while maintaining flexibility through the rubber-like properties of the flexible curing agent network
Solution Approach 2:
The patent modifies the chemical composition parameters of the resin system by incorporating specific flexible curing agents in controlled ratios (0.1-0.6 equivalents relative to epoxy groups). This parameter adjustment changes the crosslinking density and molecular structure to balance thermal performance and mechanical flexibility
2Temperature
If the ratio of inorganic filler is increased to enhance thermal conductivity, then thermal conductivity is improved, but adhesiveness to metal substrate is reduced
Solution Approach 1:
The flexible curing agent creates a composite resin system with dual functionality: the epoxy- flexible agent network provides strong adhesion to metal substrates while accommodating thermal expansion differences, allowing high inorganic filler loading without compromising bond strength
Solution Approach 2:
The patent creates local regions of flexible polymer chains at the resin-metal interface through the use of flexible curing agents, which provide both adhesion and stress relief, while the bulk material maintains thermal conductivity through inorganic filler distribution
3Temperature
If the ratio of inorganic filler is increased, then thermal conductivity is improved, but the electrical insulating layer cracks at high temperature during soldering
Solution Approach 1:
The patent adjusts the resin system composition by incorporating flexible curing agents that modify the thermal and mechanical parameters of the cured resin. This creates a resin matrix with lower glass transition temperature and higher elongation at break, enabling it to withstand soldering temperatures without cracking
Solution Approach 2:
The flexible curing agent creates a pre-compliant resin matrix that anticipates and absorbs thermal stress during subsequent high-temperature soldering processes, preventing crack initiation and propagation before they can occur
4Strength
If a resin composition with low elastic modulus is used to improve flexibility, then flexibility is improved, but ionic impurities reduce electric and physical properties
Solution Approach 1:
The patent creates a composite system where flexible curing agents provide the required low elastic modulus and flexibility, while the epoxy resin matrix maintains electrical stability and resistance to ion migration, achieving both mechanical and electrical performance
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 composition achieves excellent flexibility, adhesiveness, and thermal resistance, preventing cracking and dielectric strength reduction, even when filled with thermal conductive inorganic fillers, and allows for stable use in harsh environments, such as high-temperature soldering and high-humidity conditions.
Implementation Method 1
a copolymer of aromatic vinyl and conjugated diene compounds, a polymerizable monomer with terminal reactive double bonds, and an oligomer with a ring structure, which undergoes radical polymerization to form a crosslinked structure
Implementation Method 2
optionally includes a partially hydrogenated rubber-like polymer for improved oxidative stability
Data Source
AI summary
Provided is an electrical insulating resin composition capable of forming an electrical insulating layer which has excellent flexibility and board adhesiveness, together with high thermal resistance and high humidity resistance, tolerates a high temperature treatment at soldering and can be stably used for a long time under a harsh environment with high temperature and vibration in an automobile. A resin composition containing as organic components at least a rubber like polymer compound (A) composed of a copolymer of an aromatic vinyl compound and a conjugated diene compound and a polymerizable monomer (B) having one or more terminal reactive double bonds is employed as the electrical insulating resin composition. The compound (A) may be partially hydrogenated. The composition may optionally contain an oligomer (C) having a ring structure and having a reactive unsaturated bond in the molecule thereof.