Why Silica Powder Matters for EMC
Epoxy Molding Compound (EMC) is the core material of semiconductor packaging. As its primary filler, silica powder accounts for 70-90% of the composition, directly affecting packaging reliability, thermal performance and molding process.
Five Key Selection Criteria for EMC Silica
1. Purity
Low sodium, chloride and iron content is required (Na+Cl typically <10ppm) to ensure insulation and long-term reliability.
2. Particle Size Distribution
Proper coarse-fine gradation (bimodal or trimodal distribution) achieves maximum packing density while balancing flowability and moldability.
3. Sphericity
Spherical silica offers better flowability, higher loading and lower viscosity, reducing damage to wire bonds. EMC typically requires sphericity ≥90%.
4. Low Alpha Radiation
Radiation-sensitive devices such as memory require low-alpha silica (alpha rate <0.01cph/cm²) to reduce soft error rate (SER).
5. Moisture & Surface Treatment
Low moisture (<0.1%) prevents voids and moisture absorption; proper surface treatment (e.g., silane coupling agents) improves compatibility with epoxy resin.
Recommended Products
Maylynk SS series spherical silica (SS-2/SS-3/SS-5/SS-10) is designed for high-fill EMC with sphericity ≥95% and optional low-alpha grades. The FS series fused silica suits conventional EMC applications with low CTE. Contact us for samples and technical datasheets.
Frequently Asked Questions
- What is the typical loading of silica in EMC? Usually 70-90%, depending on package type and process.
- Spherical or angular silica? Choose spherical for high-fill and low-viscosity needs; angular is fine for conventional applications.
- Is low-alpha grade necessary? Essential for radiation-sensitive devices like memory; conventional grades suffice for general components.