Cyanate Ester Prepreg Flame Retardancy
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Solution Overview
Problem
Conventional laminates for semiconductor plastic packages face challenges with moisture resistance, heat resistance, and thermal expansion mismatch, leading to warping and unreliable connections, while existing flame retardants pose environmental concerns and toxicity risks.
Innovation Solution
A resin composition combining cyanate ester resin, non-halogen epoxy resin, silicone rubber powder, and fused silica filler, which enhances curability, flame retardancy, and reduces thermal expansion without using halogen or phosphorus compounds, improving the reliability and safety of semiconductor packages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If inorganic filler is incorporated to decrease the coefficient of thermal expansion, then thermal expansion is reduced, but the resin composition becomes fragile and drilling processing quality deteriorates
Solution Approach 1:
The patent uses a composite resin system combining cyanate ester resin with thermosetting and thermoplastic resins, incorporating both inorganic filler and rubber elasticity powder. This composite approach allows the inorganic filler to reduce thermal expansion while the rubber elasticity powder compensates for fragility, maintaining drilling processing quality despite the presence of filler particles.
Solution Approach 2:
The patent specifies precise parameter ranges: inorganic filler at 30-150 parts by weight per 100 parts resin composition, and rubber elasticity powder at 1-30 parts by weight per 100 parts resin composition. By optimizing these parameters, the patent achieves the balance between thermal expansion reduction and maintaining processability.
2Object-affected harmful factors
If bromic flame-retardants are used to render laminates flame-resistant, then flame retardancy is improved, but environmental safety deteriorates due to toxicity concerns
Solution Approach 1:
The patent changes the chemical composition parameters by completely excluding halogen compounds and phosphorus compounds from the resin system. Instead, it achieves flame retardancy through the inherent properties of cyanate ester resin and by incorporating specific inorganic fillers that provide fire resistance without toxic byproducts.
Solution Approach 2:
The patent replaces expensive and environmentally problematic flame retardant chemicals with a formulation approach using naturally flame-resistant resin systems and inorganic fillers, eliminating the need for harmful additive-based flame retardants.
3Ease of manufacture
If phenol novolak type cyanate ester resins are used, then curability is improved, but adhesion to metal foil and moisture resistance deteriorate due to remaining unreacted cyanate groups
Solution Approach 1:
The patent creates a composite resin system where phenol novolak type cyanate ester resin is combined with other cyanate ester resins, thermosetting resins, and thermoplastic resins. This composite formulation ensures complete reaction of cyanate groups while maintaining curability, eliminating the issue of unreacted groups that cause poor adhesion and moisture resistance.
Solution Approach 2:
The patent merges multiple resin types in specific weight ratios: phenol novolak type cyanate ester resin (10-50 parts), other cyanate ester resins (30-70 parts), thermosetting resins (0-70 parts), and thermoplastic resins (0-50 parts). This combination allows the benefits of phenol novolak curability while compensating for its deficiencies through the other resin components.
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 high glass transition temperature, excellent heat resistance, and low thermal expansion, ensuring reliable connections and environmental safety for semiconductor packages with enhanced flame retardancy and processability.
Implementation Method 1
curability is increased by decreasing reaction inhibition factors
Implementation Method 2
the coefficient of thermal expansion of semiconductor elements is 3 to 6 ppm/°C. It is smaller than the coefficient of thermal expansion of general printed wiring boards
Implementation Method 3
organic fillers having rubber elasticity are incorporated into varnishes containing epoxy resins
Implementation Method 4
high-degree flame retardancy without a halogen compound or a phosphorus compound
Data Source
AI summary
A prepreg for a printed wiring board, comprising a cyanate ester resin having a specific structure, a non-halogen epoxy resin, a silicone rubber powder as a rubber elasticity powder, an inorganic filler and a base material, which prepreg retains heat resistance owing to a stiff resin skeleton structure, has high-degree flame retardancy without the use of a halogen compound or a phosphorus compound as a flame retardant, and has a small thermal expansion coefficient in plane direction without using a large amount of inorganic filler, and a laminate comprising the above prepreg.