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Investigation of microlens array (MLA) replicated on polymer and glass substrates using partial filling hot embossing assisted with CO2 laser irradiation / Raja Murfiqah Binti Raja Mohamad Fouzy

By:

Raja Murfiqah Raja Mohamad Fouzy [author.]

Material type: Text

text

Media type:

unmediated

Carrier type:

volume

ISBN:

THE0010073 (Local)

Subject(s):

Dissertation note: Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2025 Abstract: Micro/nanostructures are essential in advanced technologies across industries such as biomedical, electronics, imaging, and optics. This study explores the integration of partial filling hot embossing (PFHE) with CO₂ laser irradiation for fabricating microlens arrays (MLAs) on polymer and glass substrates. The CO₂ laser eliminates the need for preheating, soaking, holding, and cooling steps, reducing thermal cycle time from 15 minutes to under 10 seconds. This approach enhances efficiency and reduces costs compared to conventional hot embossing. Conventional hot embossing experiments demonstrated that temperature, pressing load, and holding time significantly influence replication quality. Elevated temperatures soften thermoplastic materials like PMMA, improving mold filling through reduced viscosity. An optimal pressing load (1 MPa) ensures complete mold cavity filling, while insufficient load leads to incomplete formation. Similarly, holding time of 6 minutes produces precise MLA features by allowing thorough material flow, compared to inadequate results at shorter durations. The PFHE method with CO₂ laser irradiation leverages silicon molds' high transmittance and PMMA's strong optical absorption at a 10.6 μm wavelength. Optimized parameters— laser power (30 W), scanning speed (100 mm/s), and irradiation time (9 s)—achieve MLAs with lens diameters of 100 μm, 300 μm, and 500 μm, alongside a smooth surface finish (roughness of 0.032 μm). Lower power levels, insufficient irradiation times, or high scanning speeds result in incomplete patterns, while prolonged heating at slower scanning speeds (50 mm/s) causes deformation. This approach not only addresses challenges of conventional hot embossing but also enhances mold durability and process efficiency. The PFHE with CO₂ laser irradiation offers a fast, low-cost, and highthroughput solution for MLA fabrication, demonstrating strong potential for industrial applications and significant cost savings.

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Holdings ( 2 )
Title notes ( 4 )

Holdings
Item type	Current library	Call number	Status	Date due	Barcode
Thesis	UMPLIB PEKAN	FTKPM .M87 2025 r Thesis (Browse shelf(Opens below))	Not for loan		T000003569
Thesis	UMPLIB PEKAN	CD13763 (Browse shelf(Opens below))	Final Processing		T000003570

Faculty of Manufacturing & Mechatronics Engineering Technology

Thesis (Doctor of Philosophy) -- Universiti Malaysia Pahang – 2025

Includes bibliographical references

Micro/nanostructures are essential in advanced technologies across industries such as biomedical, electronics, imaging, and optics. This study explores the integration of partial filling hot embossing (PFHE) with CO₂ laser irradiation for fabricating microlens arrays (MLAs) on polymer and glass substrates. The CO₂ laser eliminates the need for preheating, soaking, holding, and cooling steps, reducing thermal cycle time from 15 minutes to under 10 seconds. This approach enhances efficiency and reduces costs compared to conventional hot embossing. Conventional hot embossing experiments demonstrated that temperature, pressing load, and holding time significantly influence replication quality. Elevated temperatures soften thermoplastic materials like PMMA, improving mold filling through reduced viscosity. An optimal pressing load (1 MPa) ensures complete mold cavity filling, while insufficient load leads to incomplete formation. Similarly, holding time of 6 minutes produces precise MLA features by allowing thorough material flow, compared to inadequate results at shorter durations. The PFHE method with CO₂ laser irradiation leverages silicon molds' high transmittance and PMMA's strong optical absorption at a 10.6 μm wavelength. Optimized parameters— laser power (30 W), scanning speed (100 mm/s), and irradiation time (9 s)—achieve MLAs with lens diameters of 100 μm, 300 μm, and 500 μm, alongside a smooth surface finish (roughness of 0.032 μm). Lower power levels, insufficient irradiation times, or high scanning speeds result in incomplete patterns, while prolonged heating at slower scanning speeds (50 mm/s) causes deformation. This approach not only addresses challenges of conventional hot embossing but also enhances mold durability and process efficiency. The PFHE with CO₂ laser irradiation offers a fast, low-cost, and highthroughput solution for MLA fabrication, demonstrating strong potential for industrial applications and significant cost savings.