In the precision moulding of polymeric microfluidic chips with designs of complicated channel structure, precision moulding of micro features with sizes down to microns and sub-micrometers are often required. In order to successfully fill these micro features on mould cavity during injection moulding, the management of cavity entrapped air is critical for minimizing the variation in melt pressure distribution during the injection phase and also avoids polymer degradation at the last filling zone. In this paper, an investigation study was conducted to evaluate the effects of vacuum assist moulding on chip flatness and the micro-feature replication accuracy of the polymeric microfluidic chips as compared to conventional injection moulding process. Process optimization with the Design of Experiment (DOE) method is used to optimize the processing conditions which defined a processing window for the vacuum assisted micro-injection moulding process. The replication accuracy of vacuum assisted moulded polymeric chips achieved less than 1% error compared to the actual insert dimension. The overall warpage was controlled within 15um, which is better than that achieved by conventional micro-moulding process.
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