Semiconductor Molding Compound[2]

Updated: 2026-09-15

Overview

Semiconductor Molding Compound is a thermosetting epoxy resin composite formulated for encapsulating microelectronic components. It serves as a protective shell against moisture, chemicals, and mechanical stress while ensuring electrical insulation. Developed specifically for semiconductor packaging, these compounds undergo transfer molding processes at high temperatures and pressures. Their formulations are optimized for low thermal expansion (CTE) to match silicon chips and lead frames, preventing delamination or cracking during thermal cycling.

Physical and Chemical Properties

These compounds exhibit glass transition temperatures (Tg) ranging from 125°C to 210°C, with coefficients of thermal expansion (CTE) below 20 ppm/°C below Tg. Flame-retardant grades typically meet UL94 V-0 standards. The cured material demonstrates high dielectric strength (>15 kV/mm) and volume resistivity (>1e15 Ω·cm). Fillers like silica (60–90% by weight) reduce CTE, while additives enhance thermal conductivity (up to 2 W/mK) or UV stability for LED applications.

Main Applications

Primary use cases include encapsulation of discrete semiconductors (diodes, transistors), QFN/BGA packages, and high-power modules. Automotive-grade variants withstand -55°C to 175°C operating temperatures. LED packages demand optically reflective or light-diffusing formulations. Emerging applications include fan-out wafer-level packaging (FOWLP), where low warpage and fine-pitch compatibility are critical. Halogen-free versions are increasingly adopted for environmental compliance.

Safety and Storage

Uncured compounds may contain irritants like phenolic hardeners. Use local exhaust ventilation during molding and post-cure operations. Store in moisture-proof bags with desiccants. Shelf life is typically 6–12 months at 5°C. Thaw frozen material at room temperature for 24 hours before use to prevent condensation. Discard material if moisture absorption exceeds 0.2% (measured by Karl Fischer titration).

B2B Procurement Guide

Key specifications to evaluate include spiral flow length (150–200 cm indicates flowability), gel time (20–60 sec at 175°C), and wire sweep performance. For high-frequency applications, request dielectric constant (Dk) and loss tangent (Df) data. Supplier audits should verify ISO 9001/14001 certification and change notification procedures. Minimum order quantities (MOQs) range from 25 kg for specialty grades to tonnage quantities for standard grades. Lead times vary from 4 weeks (stock items) to 12 weeks (custom formulations).