Characterization of Micro Injection Molding Process for the Replication of Micro/Nano Features Using Bulk Metallic Glass Insert

Microsytems are motivating the development of complex, net-shape products weighing a few milligrams or having micro/nano features. Such small components or micro/nano features are subject to extreme shear rates and thermal gradients in the micro injection molding process due to their large surface to volume ratio. Detailed process monitoring and characterization are desirable to create a viable manufacturing process with acceptable part quality for MEMS and Microsystems. This work covers the replication of micro/nano scale features using Bulk Metallic Glass (BMG), implementation of a suite of PT (pressure and temperature) sensors on a commercial reciprocating micro injection molding machine, and detailed analysis of the relationship between process-rheology-replication. The results indicate that injection velocity dominates the average viscosity of polymer melts; holding pressure can adjust the input pressure history for micro/nano features and mold temperature can enhance feature filling by elevating the po-mold interface temperature. Tailored strategies to set machine parameters for different molds and plastics can be developed to meet the quality requirement for both small components and micro/nano features.