A study of self-assembled monolayer coating for non-stick encapsulation mold

A major factor that affects the reliability and production yield of green packages is the adhesion between green molding compound and encapsulation mold. The non-stick coating on molds by physical vapor deposition (PVD) has been regarded as an alternative of the environmentally unfriendly electroplated hard-Cr coating but its cost is high. In this paper, we report a self-assembled monolayer (SAM) technique that uses methacryloxypropyl trimethoxysilane (MPTMS) as the coupling agent for photo crosslinking to form a dense and durable anti-stick film on the encapsulation mold surface. The presence of the coated MPTMS thin film was identified by the X-ray photoelectron spectroscopy (XPS). Hydrophobicity and roughness of the film were analyzed through contact angle measurement and 3D optical imaging profiler, respectively. Mold releasing tests show that the MPTMS coating has a better mold releasing capability than electroplating hard-Cr and PVD CrN coatings.