Liquid Resin Composition for Low-Viscosity Power Module Encapsulation
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Solution Overview
Problem
Existing liquid encapsulating materials for power semiconductor elements face challenges with high viscosity, sedimentation of inorganic fillers, and reduced reliability due to cracking, which affects the heat resistance and workability of the encapsulating resin.
Innovation Solution
A liquid resin composition is developed that includes an epoxy resin with an alicyclic epoxy resin, an acid anhydride, a curing accelerator, an inorganic filler, and a sedimentation preventing agent, which maintains low viscosity and reduces filler sedimentation, ensuring excellent workability and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If inorganic filler is added to reduce linear expansion coefficient, then heat resistance is improved, but viscosity increases and workability deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the epoxy resin system by selecting specific epoxy resins with appropriate viscosity and reactivity, and matching them with corresponding curing agents and accelerators. This parameter optimization allows the resin to maintain low viscosity even with high inorganic filler content (65-85% by mass), resolving the contradiction between heat resistance and workability
Solution Approach 2:
The patent creates a composite material system combining epoxy resin, curing agent, curing accelerator, and inorganic filler in specific proportions. This composite approach allows the synergistic effect of components to maintain low viscosity while achieving high heat resistance through the inorganic filler, thus resolving the technical contradiction
2Temperature
If inorganic filler is added to reduce linear expansion coefficient, then heat resistance is improved, but sedimentation occurs during curing and reliability decreases
Solution Approach 1:
The patent introduces a coupling agent as an intermediary substance that chemically bonds between the inorganic filler particles and the epoxy resin matrix. This coupling agent prevents filler sedimentation during curing by creating strong interfacial adhesion, thereby maintaining material homogeneity and preventing cracks that would reduce reliability, while still allowing high filler content for heat resistance
Solution Approach 2:
The patent optimizes the particle size distribution and surface treatment parameters of the inorganic filler to prevent sedimentation. By controlling these parameters and matching them with appropriate curing accelerators, the resin maintains homogeneity during curing, preventing the formation of weak zones that would lead to cracking
3Stability of the object's composition
If inorganic filler content is increased to reduce linear expansion, then thermal stability is improved, but viscosity increases and casting workability deteriorates
Solution Approach 1:
The patent carefully controls the particle size, shape, and surface characteristics of the inorganic filler, and optimizes the viscosity and molecular weight of the epoxy resin. These parameter changes allow high filler content (65-85% by mass) to be achieved while maintaining low viscosity and excellent casting workability
Solution Approach 2:
The patent applies local quality optimization by using filler particles with specific surface treatments and size distributions in different regions of the composition. This localized optimization ensures uniform dispersion and low viscosity throughout the material, while achieving the desired low linear expansion coefficient
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 resin composition achieves excellent workability, reduced sedimentation of inorganic fillers, and enhanced heat resistance, resulting in a power device with improved crack resistance, electrical, mechanical, and thermal properties.
Implementation Method 1
a sedimentation preventing agent... reduces sedimentation of the inorganic filler during storage
Implementation Method 2
the epoxy resin (A) includes an alicyclic epoxy resin, and a viscosity of the liquid resin composition at 25°C is 75 Pa·s or less
Implementation Method 3
an encapsulating material for a power module is required to have low linear expansion... In order to reduce the coefficient of linear expansion, it is common practice to add an inorganic filler
Implementation Method 4
the liquid resin composition containing: (A) an epoxy resin; (B) an acid anhydride
Data Source
AI summary
Provided is a liquid resin composition used for encapsulating, by a casting method, a power module which includes a substrate for a power module, over which a circuit layer is formed, and a power semiconductor element mounted over the circuit layer of the substrate for a power module, the liquid resin composition containing (A) an epoxy resin, (B) an acid anhydride, (C) a curing accelerator, (D) an inorganic filler, and (E) a sedimentation preventing agent, in which the epoxy resin (A) includes an alicyclic epoxy resin, and a viscosity of the liquid resin composition at 25°C is 75 Pa·s or less.