Vacuum venting enhances the replication of nano/micro-features in microinjection molding process

Abstract

Vacuum venting is a method proposed to improve feature replication in microparts that are fabricated using micro injection molding (MIM). A qualitative and quantitative study has been carried out to investigate the effect of vacuum venting on nano/micro feature replication in MIM. Anodized aluminium oxide containing nanofeatures and a bulk metallic glass tool mold containing micro features were used as mold inserts. The effect of vacuum pressure at constant vacuum time, and of vacuum time at constant vacuum pressure on the replication of these features is investigated. It is found that vacuum venting qualitatively enhances the nano-scale feature definition as well as increases the area of feature replication. In the quantitative study, higher aspect ratio features can be replicated more effectively using vacuum venting. Increasing both vacuum pressure and vacuum time are found to improve the depth of replication, with the vacuum pressure having more influence. Feature orientation and final sample shape could affect the absolute depth of replication of a particular feature within the sample.