Opportunity
In modern plastic molding industries, particularly in semiconductor IC molding and packaging, a critical challenge is the adhesion of epoxy molding compounds (EMC) to the surface of injection molds. During the molding process, EMC tends to cure and adhere to the mold surfaces, leading to frequent cleaning cycles (e.g., every 500 operations) and reduced productivity. Traditional solutions involve applying release agents (e.g., silicone or fluoropolymer coatings), which are time-consuming, costly, and often degrade under high temperatures (145–200°C). Moreover, the abrasive fillers and chemical additives in EMC exacerbate wear and corrosion of mold components. Existing hard coatings like electroplated chromium (Cr) or PVD coatings (e.g., TiN, CrN) exhibit high surface energy (>30 mN/m) and hydrophilic properties, making them prone to adhesion. There is a pressing need for a durable, high-performance anti-adhesion material that combines low surface energy, high hardness, and thermal stability to address these limitations.
Technology
The patent introduces an innovative anti-adhesion material composed of at least one hard-phase material (e.g., transition metal nitrides like CrN, MoN) and a soft-phase metal (e.g., Ni, 10–30 at.%). The material is fabricated via physical vapor deposition (PVD), specifically plasma-enhanced magnetron sputtering, which embeds soft-phase metal grains into the hard-phase matrix to form a fine-grained, dense microstructure. This design eliminates the columnar grain structure and porosity typical of conventional PVD coatings, resulting in a surface with ultra-low total surface energy (≤20 mN/m) and high hydrophobicity (water contact angle: 110–120°). Key innovations include:
- Multi-Phase Composition: The Cr-Mo-Ni-N system forms a hybrid of Cr₂N, CrN, MoN, and Ni phases, enhancing mechanical properties (hardness: 30–35 GPa) and fracture toughness.
- Surface Energy Control: The material’s surface polarity is reduced to 0.1–0.2 mN/m, mimicking polytetrafluoroethylene (PTFE) but with superior wear resistance.
- Process Optimization: A closed-loop plasma emission monitoring (PEM) system dynamically adjusts reactive gas flow (N₂/O₂) during sputtering to stabilize coating stoichiometry.
Advantages
- Low Adhesion: Reduces EMC adhesion force by 95% compared to uncoated molds.
- High Durability: 40× higher wear resistance than steel; steady-state friction coefficient of 0.3–0.4. Thermal Stability: Retains properties at temperatures up to 500°C.
- Corrosion Resistance: 20,000× improvement in acid resistance over steel substrates.
- Eco-Friendly: Eliminates need for liquid release agents.
Applications
- Semiconductor Packaging: Molds for IC encapsulation with EMC.
- Plastic Injection Molding: Non-stick coatings for high-temperature polymers (e.g., PPS, PPA).
- Tooling: Wear-resistant coatings for screws, nozzles, and feed rods.
- Aerospace/Automotive: Lightweight composite molding tools.
