Naphthalene Epoxy Resin Composition for Lead-Free Soldering
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Solution Overview
Problem
Current epoxy resin compositions for semiconductor encapsulation face challenges such as warpage after molding, delamination, high moisture absorption, and compromised flow during molding, especially with the transition to lead-free solders, which require higher soldering temperatures and result in increased modulus and moisture absorption.
Innovation Solution
An epoxy resin composition combining a naphthalene type epoxy resin with a phenolic resin curing agent and an inorganic filler, along with a phosphazene compound, which provides good flow, low coefficient of linear expansion, high glass transition temperature, minimal moisture absorption, crack resistance, and flame retardance without using brominated epoxy resins or antimony trioxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the crosslink density of resins is increased to elevate glass transition temperature, then heat resistance is improved, but moisture absorption increases and delamination occurs at interfaces
Solution Approach 1:
The patent changes the chemical structure parameters of the epoxy resin by introducing naphthalene rings and controlling the ratio of specific epoxy resin components (formula (i) at 40-95 parts and formula (ii) at 5-60 parts per 100 parts total). This structural modification allows achieving high glass transition temperature (above 140°C) while maintaining low moisture absorption (0.15-0.30%) and good interface adhesion, resolving the contradiction between heat resistance and interface reliability
Solution Approach 2:
The patent creates a composite resin system combining multiple epoxy resin components with specific curing agents and inorganic fillers (60-90 mass% of total composition). The synergistic combination of naphthalene-type epoxy resins, phenolic curing agents, and controlled inorganic filler content (10-40 mass%) achieves both high heat resistance and maintained interface adhesion by balancing crosslink density and moisture uptake
2Reliability
If more inorganic filler is loaded to provide low water absorption and low coefficient of expansion, then moisture resistance is improved, but viscosity increases and flow during molding is compromised
Solution Approach 1:
The patent optimizes the particle size parameters of inorganic fillers to D50=3-20 μm and D90<40 μm, and controls the filler content at 60-90 mass% of total composition. This parameter optimization maintains low viscosity during molding (enabling good flow) while achieving low moisture absorption (0.15-0.30%) and low coefficient of linear expansion (60-90 ppm/K), resolving the contradiction between moisture resistance and moldability
Solution Approach 2:
The patent applies surface treatment to inorganic fillers using silane coupling agents or titanate coupling agents, creating different properties at the filler surface versus the bulk material. This surface modification improves dispersion and reduces aggregation, maintaining good flow during molding while enhancing moisture resistance and interfacial adhesion, thus resolving the contradiction between moldability and moisture resistance
3Adaptability or versatility
If lead-free solders are used to eliminate lead, then environmental compliance is improved, but soldering temperature increases and causes delamination and crack
Solution Approach 1:
The patent modifies the resin's thermal properties by incorporating naphthalene-type epoxy resins with specific molecular structures and controlling the crosslink density through curing agent selection. This achieves high glass transition temperature (above 140°C) and appropriate modulus at elevated temperatures, enabling the resin to withstand lead-free soldering temperatures (200-250°C) without delamination or crack, thus resolving the contradiction between environmental compliance and crack resistance
Solution Approach 2:
The patent matches the coefficient of linear expansion of the cured resin (60-90 ppm/K) to be close to that of common substrates and semiconductor chips. This thermal expansion matching reduces thermal stress during lead-free soldering processes, preventing delamination and crack even at high soldering temperatures, thereby resolving the contradiction between environmental compliance 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 composition achieves full flowability, low coefficient of linear expansion, high glass transition temperature, minimal moisture absorption, and enhanced flame retardance and moisture-proof reliability, making it suitable for semiconductor encapsulation and improving the reliability of semiconductor devices.
Implementation Method 1
by further adding a phosphazene compound of the compositional formula (2), shown below, the composition is improved in flame retardance and moisture-proof reliability
Implementation Method 2
an epoxy resin composition comprising (A) an epoxy resin... (B) a curing agent... which provides... a high glass transition temperature, minimal moisture absorption
Data Source
AI summary
An epoxy resin composition comprising (A) a naphthalene type epoxy resin in which 35-85 parts by weight of 1,1-bis(2-glycidyloxy-1-naphthyl)alkane and 1-35 parts by weight of 1,1-bis(2,7-diglycidyloxy-1-naphthyl)alkane are included per 100 parts by weight of the resin, (B) a curing agent in the form of a naphthalene type phenolic resin, (C) an inorganic filler, and (D) a phosphazene compound is best suited for semiconductor encapsulation because it has good flow, a low coefficient of linear expansion, a high Tg, minimal moisture absorption, and crack resistance upon lead-free soldering.