Manufacturing of 3D Microlens Array Mold on Bulk Metallic Glass by Self-Aligned Multi-Ball Hot Embossing
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Manufacturing of 3D Microlens Array Mold on Bulk Metallic Glass by Self‑Aligned Multi‑Ball Hot Embossing Xiaohua Liu1,2 · Ruodong Mo1 · Kangsen Li1 · Jun Shen1 · Jiang Ma1 · Feng Gong1 Received: 10 May 2020 / Revised: 24 August 2020 / Accepted: 1 September 2020 © Korean Society for Precision Engineering 2020
Abstract Bulk metallic glasses (amorphous alloys) exhibiting both high hardness and extraordinary thermoplastic forming ability, are perfect mold material for 3D optical microlens array. However, conventional 3D micro fabrication for metallic glass requires Si templates which are extremely costly and eco-unfriendly to machine and demold. In this study, we report a green and lowcost self-aligned multi-ball hot embossing process to create 3D micro dimple array on metallic glass by replicating spherical crowns of self-aligned precision balls. A 3D metallic glass micro dimple array with aperture of 867.2 μm and surface roughness of 8.2 nm was fabricated in 30 s. Different from conventional hot embossing that material full-filled into mold, the new process enables micro dimple fabrication with different specifications by freely controlling the down displacement of balls. Therefore, the relationship between down displacement and depth of micro dimple was revealed through exploring the material flow behavior by a verified FE model. In addition, to test the feasibility of the fabricated metallic glass mold, a PMMA compound eye structure was embossed and its focusing and imaging performance were subsequently evaluated. This research demonstrates a new manufacturing process for rapid fabrication of 3D microlens arrays metallic glass mold in a neat and economic way. Keywords Bulk metallic glass · 3D microlens array mold · Self-aligned multi-ball hot embossing · Material flow behavior
1 Introduction Bulk metallic glasses (BMGs) possess excellent mechanical properties including extremely high specific strength [1], super wear and corrosion resistance [2] as well as low elastic modulus with large elastic limit [3], which have aroused extensive interests since they were firstly prepared by Klement et.al in 1960 [4]. Despite these remarkable engineering features, BMGs are especially known for their excellent
* Jiang Ma [email protected] * Feng Gong [email protected] 1
Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering, College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen 518060, China
Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
2
formability in the supercooled liquid region, which enables efficient and environment-friendly thermoplastic forming of metallic glasses like polymers or oxide glasses [5]. Benefiting from this ability, unlike general hard material processed by material removal methods such as etching and precision cutting, BMGs are capabl
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