Epoxy Underfill for Flip-Chip Void Prevention
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Solution Overview
Problem
Conventional underfill materials for flip-chip semiconductor devices face challenges in maintaining reliability due to increased bump density, narrower gaps, and the use of lead-free solder, which is more brittle, leading to void generation, uneven fillet formation, and stress-related breakdowns.
Innovation Solution
A liquid resin composition comprising a liquid epoxy resin, a curing agent with a liquid aromatic amine, a hardening accelerator, and silicone polymer particles is developed to enhance fluidity, reduce voids, and improve adhesiveness and stress dissipation, while maintaining moisture and thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of bumps is increased and bump pitch is decreased to achieve higher integration, then productivity and functionality are improved, but the gap between semiconductor element and substrate becomes narrower making void generation more likely
Solution Approach 1:
The patent modifies the physical and chemical parameters of the underfill material, specifically controlling viscosity (0.1 to 10 Pa·s at 25°C), surface tension (20 to 35 mN/m), and gel time (10 to 300 seconds at 150°C) to enable proper flow into narrow gaps while preventing void formation during curing
Solution Approach 2:
The underfill material is formulated as a composite system containing epoxy resin, aromatic amine curing agent, rubber particles (5-50 μm diameter), and inorganic filler, where each component contributes specific properties that collectively solve the void generation problem in narrow gaps
2Area of stationary object
If chip size is increased to accommodate higher integration, then functionality is improved, but the flow pathway becomes more complicated making voids easier to generate
Solution Approach 1:
The patent optimizes the viscosity parameter (0.1 to 10 Pa·s) to balance flow capability across large chip areas while maintaining control during dispensing, and adjusts gel time (10 to 300 seconds) to allow complete filling of complicated flow pathways before curing begins
Solution Approach 2:
Rubber particles (5-50 μm) act as intermediaries that modify the rheological properties of the underfill material, enhancing its ability to navigate complicated flow pathways and fill gaps uniformly across large chip areas without trapping voids
3Adaptability or versatility
If lead-free solder is used to meet environmental requirements, then environmental compliance is improved, but mechanical brittleness increases making bump connection reliability more difficult to maintain
Solution Approach 1:
Rubber particles (5-50 μm) are incorporated into the underfill material to provide flexible, stress-absorbing characteristics that compensate for the brittleness of lead-free solder, maintaining bump connection reliability through mechanical compliance
Solution Approach 2:
The underfill material is designed as a composite system combining epoxy resin with rubber particles and inorganic filler, creating a material that exhibits both structural integrity and mechanical flexibility to support brittle lead-free solder bumps
4Area of stationary object
If the underfill material is required to flow on large areas in narrow gaps, then coverage is improved, but the formulation becomes more complex
Solution Approach 1:
The patent establishes specific parameter ranges for viscosity (0.1 to 10 Pa·s), surface tension (20 to 35 mN/m), and gel time (10 to 300 seconds) that enable the material to flow across large areas while maintaining formulation simplicity through controlled composition
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 effectively prevents void generation, ensures even fillet formation, and enhances the reliability of flip-chip semiconductor devices by improving adhesiveness and stress management, even with lead-free solder and larger semiconductor elements.
Implementation Method 1
a curing agent containing a liquid aromatic amine
Implementation Method 2
a hardening accelerator
Implementation Method 3
silicone polymer particles
Data Source
AI summary
The invention relates to a liquid resin composition for electronic components which is used in sealing of electronic components, comprising a liquid epoxy resin, a curing agent containing a liquid aromatic amine, and an inorganic filler, and further comprising at least one member selected from a hardening accelerator, silicone polymer particles, and a nonionic surfactant. There is thereby provided a liquid resin composition for electronic components, which is excellent in fluidity in narrow gaps, is free of void generation, is excellent in adhesiveness and low-stress characteristic and is excellent in fillet formation, as well as an electronic component device having high reliability (moisture resistance, thermal shock resistance), which is sealed therewith.