Alicyclic Epoxy Terminated Polysiloxane: High Refractive Index & Low Stress for Refractive Index Matching in Optoelectronic Encapsulation Changfu BEX12B

As optoelectronic and semiconductor devices develop toward higher power, miniaturization and superior optical efficiency, optical encapsulation materials are required to deliver better performance in refractive index matching, yellowing resistance, low stress and long-term reliability. Changfu^® BEX12B is a high-refractive-index alicyclic epoxy terminated polysiloxane. High-refractive phenyl groups are incorporated into the siloxane backbone, with alicyclic epoxy functional groups retained at both terminals. It combines the flexible siloxane skeleton with high refractive index properties. When participating in crosslinking and curing of epoxy systems, it effectively mitigates refractive index mismatch in optoelectronic encapsulation and serves well for formulations requiring high refractive index.

Product Features

✅ High Refractive Index & Outstanding Yellowing Resistance

The phenyl backbone raises molar refractivity, narrows the refractive index gap between encapsulation resin and optical chips and reduces interfacial reflection loss. It also improves heat and aging resistance, greatly suppressing yellowing under long-term photo-thermal conditions and securing stable optical performance.

✅ High Reactivity & Tunable Crosslinking System

Alicyclic epoxy groups on both ends of the molecule feature excellent reactivity, compatible with cationic curing systems. Crosslink density can be flexibly adjusted according to formulation requirements.

✅ Excellent Compatibility with Epoxy Resins

It is miscible with mainstream epoxy resins including alicyclic epoxy and bisphenol‑A epoxy, improving leveling of the system. It brings low surface tension to the formulation with favorable lubricating and defoaming effects.

✅ Low Curing Internal Stress & Balanced Comprehensive Properties

Flexible siloxane segments relieve internal stress caused by curing shrinkage, significantly lowering risks of cracking and delamination of devices under thermal cycling. Cured products feature good dielectric performance, weather resistance and coating hardness.

Applications

l  Optical Encapsulation for LED & Optoelectronic Devices

Used for high-power LED encapsulation resins and optical coupling adhesives. Refractive index matching cuts interfacial light reflection to boost light extraction efficiency; low curing stress enhances thermal shock resistance and provides long-term protection against photo-thermal yellowing.

l  Optical Coatings & Optical Films

Used for high-transmittance protective films and wear-resistant lens coatings. It tunes coating refractive index while maintaining high visible light transmittance, improving weather resistance, hardness and elasticity to avoid coating cracking under temperature variation.

l  High-End Semiconductor Electronic Encapsulation

Used as a modifier for epoxy molding compounds and optical-grade encapsulation resins. Flexible siloxane chains ease epoxy curing shrinkage stress and deliver favorable dielectric properties, suitable for hybrid optoelectronic-semiconductor packaging.

l  Special Optical Adhesives & Sealants

Used for high-RI optical adhesives and optical coupling sealants. It strengthens interfacial bonding, improves the flexibility of cured layers, and balances optical transparency and long-term bonding reliability.

Changfu^® BEX12B high-refractive-index alicyclic epoxy terminated polysiloxane balances optical performance, curing process and device reliability. It provides high-performance silicone modification solutions for high-end sectors including optoelectronic encapsulation, optical coatings and semiconductor packaging. We help customers optimize formulations and improve the optical efficiency and service life of end products.

(Note: The specific application shall be determined according to actual conditions. Feel free to contact our technical team for relevant technical service support.)

For more information about our products and applications, please contact:

Mobile: (+86) 181-6277-0058

Email: sales@cfsilanes.com

Key words: High-refractive-index;  Alicyclic epoxy terminated polysiloxane;  Optoelectronic encapsulation;  Optical coatings; Semiconductor packaging.