The Novel Fabrication Method and Optimum Tooling Design Used for Microlens Arrays

This paper reports a simple and novel procedure for mass production of microlens arrays. In this paper, a microlens array master is formed by room temperature imprint lithography and thermal reflow process. Next, electroforming is carried out to fabricate the metal mold insert from the microlens array master. Finally, micro-hot embossing is used to replicate microlens arrays. In this paper, a L₉ experimental matrix design based on the Taguchi method is constructed to optimize the replication quality of molded microlens arrays. The results of the statistical analysis indicated that the processing temperature is the principal parameter affecting the sag height of the molded microlens array. The optimal processing parameters are processing temperature of 150degC, embossing pressure of 5.21MPa, processing time of 90s and de-molding temperature of 70degC. The 200times200 arrays of molded microlens, with a diameter of 150mum, a pitch of 200mum and a sag height of 31.51mum have been successfully fabricated. The average surface roughness of the molded microlens array is 4.31nm