Manufacturing of Micro-Lens Array Using Contactless Micro-Embossing with an EDM-Mold

Kangsen Li,Feng Gong,Gang Xu,Zhiwen Xie,Xinfang Huang

doi:10.3390/app9010085

Kangsen Li, Feng Gong + Show 3 more

Open Access

https://doi.org/10.3390/app9010085

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Abstract

Micro embossing is an effective way to fabricate a polymethyl methacrylate (PMMA) specimen into micro-scale array structures with low cost and large volume production. A new method was proposed to fabricate a micro-lens array using a micro-electrical discharge machining (micro-EDM) mold. The micro-lens array with different shapes was established by controlling the processing parameters, including embossing temperature, embossing force, and holding time. In order to obtain the friction coefficient between the PMMA and the mold, ring compression tests were conducted on the Shenzhen University’s precision glass molding machine (SZU’s PGMM30). It was found that the friction coefficient between the PMMA specimen and the mold had an interesting change process with increasing of temperature, which affected the final shape and stress distribution of the compressed PMMA parts. The results of micro-optical imaging of micro-lens array indicated that the radius of curvature and local length could be controlled by adjusting the processing parameters. This method provides a basis for the fabrication and application of micro-lens arrays with low-cost, high efficiency, and mass production.

Highlights

The micro-lens array (MLA), called a Fly-eye lens, is widely used in optical communication, lighting displays, optical sensors, and illumination because of its unique structures and function.There are many methods that can fabricate micro-lenses, including plasma etching [1], laser ablation [2], micro-milling [3], photolithography [4], micro-injection [5], glass reflow [6] and micro hot embossing [7,8,9,10,11,12]
To understand the deformation behaviors of polymethyl methacrylate (PMMA), numerical simulation is an effective method to predict the shape of molded PMMA
The simulation results of the PMMA ring for different interface friction coefficients, assuming the ring was pressed to the same vertical displacement

Summary

Introduction

The micro-lens array (MLA), called a Fly-eye lens, is widely used in optical communication, lighting displays, optical sensors, and illumination because of its unique structures and function.There are many methods that can fabricate micro-lenses, including plasma etching [1], laser ablation [2], micro-milling [3], photolithography [4], micro-injection [5], glass reflow [6] and micro hot embossing [7,8,9,10,11,12]. Micro hot embossing is regarded as one of the most promising processes for mass production. Micro hot embossing is a flexible and low-cost technique, consisting of heating, embossing, and cooling. Many types of hot embossing processes have been reported, including PDMS (polydimethylsiloxane) soft mold imprinting [13,14,15,16,17], Deep reactive ion etching (DRIE) Si template duplicating [18], LIGA (Acronym of German words: Lithografie, Galvanik, Abformung) Ni mold copying [19], focused ion beam (FIB) mold embossing [20,21], and roll-to-roll embossing [22,23]. The quality of the embossed micro-lens depends on the precision of the mold insert

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Results

Conclusion