Liquid Resin Composition for Flexible Semiconductor Wiring
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Solution Overview
Problem
Conventional circuit boards with embedded wiring and resin compositions face challenges in achieving a balance between flexibility and stiffness, particularly when used in wafer-level chip size packages, where they often suffer from insufficient flexibility and increased brittleness due to high ceramic filler content for thermal expansion matching with semiconductors.
Innovation Solution
A liquid resin composition comprising a silicone-modified liquid epoxy resin, a liquid polyphenol curing agent, and an inorganic filler with specific particle size and content, which forms a cured product with a glass transition temperature between 50°C to 120°C and an elastic modulus of 20 GPa or less, allowing for high adhesion and flexibility while maintaining necessary stiffness for semiconductor mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filling rate of ceramic filler in resin is increased to match thermal expansion coefficient with semiconductor, then thermal expansion compatibility is improved, but flexibility of circuit board decreases and it becomes more brittle
Solution Approach 1:
The patent uses a composite resin system combining liquid epoxy resin and liquid polyphenol resin with ceramic fillers. This composite material achieves both thermal expansion compatibility (CTE matched to semiconductor) and maintained flexibility through the specific resin combination and curing characteristics, resolving the contradiction between thermal stability and mechanical flexibility.
Solution Approach 2:
The patent controls the glass transition temperature (Tg) of the cured resin within a specific range (50°C to 120°C) and limits the elastic modulus to 20 GPa or less. By adjusting these parameters through resin composition and curing conditions, the material achieves both thermal expansion matching and sufficient flexibility, preventing brittleness while maintaining thermal compatibility.
2Length of stationary object
If metallic heat dissipation plate is removed to thin the circuit board, then thickness is reduced, but flexibility is further compromised and breakage risk increases
Solution Approach 1:
The patent achieves thinning of the circuit board while maintaining flexibility by controlling the resin's glass transition temperature (50°C to 120°C) and elastic modulus (≤20 GPa). These parameter adjustments allow the thinned board to remain flexible and resistant to breakage without requiring a heat dissipation plate, thus reducing thickness while preserving mechanical properties.
3Ease of operation
If resin composition is optimized for low viscosity to fill minute parts, then filling performance is improved, but adhesion and structural integrity may be compromised
Solution Approach 1:
The patent employs a composite system of liquid epoxy resin and liquid polyphenol resin that maintains low viscosity for excellent filling performance in minute parts while achieving high adhesion through the synergistic interaction between the two resin types and the curing accelerator, thus resolving the contradiction between fillability and adhesion.
Solution Approach 2:
The curing accelerator acts as an intermediary that enables the low-viscosity liquid resin composition to achieve high adhesion and structural integrity after curing. The accelerator facilitates the curing reaction that transforms the easily-fillable liquid state into a strong, adhesive solid state, bridging the gap between filling performance and adhesion 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 provides a wiring structure and package with enhanced flexibility and reliability, suitable for thin interposers and semiconductor mounting, outperforming conventional glass epoxy boards and build-up boards in terms of flexibility and mountability without requiring additional support substrates.
Implementation Method 1
A liquid resin composition contains a liquid epoxy resin, a liquid curing agent, a curing accelerator and a ceramic filler. The liquid curing agent has a plurality of phenolic hydroxy groups per molecule.
Implementation Method 2
The ceramic filler has an average particle diameter of 50 μm or less, and a content of the ceramic filler in the liquid resin composition is in a range from 50% to 90% by mass, inclusive. The liquid resin composition has a viscosity of 100 Pa·s or less at 25° C.
Implementation Method 3
A cured product of the liquid resin composition has a glass transition temperature in a range from 50° C. to 120° C., inclusive and an elastic modulus of 20 GPa or less at 25° C.
Data Source
AI summary
A liquid resin composition includes a liquid epoxy resin, a liquid curing agent, a curing accelerator and a ceramic filler. The liquid epoxy resin contains a first epoxy resin having a polyalkylene glycol framework. The liquid curing agent has a plurality of phenolic hydroxy groups per molecule. A content of the first epoxy resin in the liquid epoxy resin is in a range from 30% to 70% by mass, inclusive. The ceramic filler has an average particle diameter of 50 μm or less, and a content of the ceramic filler in the liquid resin composition is in a range from 50% to 90% by mass, inclusive. The liquid resin composition has a viscosity of 100 Pa·s or less at 25° C.