Chap.8 Plastic Optical Devices Manufacturing Precision Manufacturing and Inspection of Optical Components Chap.8 Plastic Optical Devices Manufacturing Speaker: Ching-Yao Huang(黃靖堯) Advisor: Prof. Yi-Pai Huang(黃乙白教授) Prof. Chung-Hao Tien(田仲豪教授) Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan Jan. 17 2008

Outline Injection Molding - Micro Injection Molding - Introduction - Micro Injection Molding - Micro Injection-compression Molding - Optical Plastic Material Hot Embossing Molding - Manufacturing Parameter - Different ways to Micro Hot embossing Molding Conclusions

Injection Molding Disadvantages: Because of pressure, T, density Sink mark Shrinkage Residual stress Warpage filling stage packing stage cooling stage

Micro Injection Molding Definition: The products weight unit uses mg. Size unit uses μm. 4 types: Weight Size 1 mg x 2 μm 3 4 microstructure μm

Micro Injection-compression Molding Add compression mold process base on normal micro injection molding. Advantages: Reduce ejection pressure Reduce residual stress Reduce molecular orientation Overcome sink mark and warpage Increase size precision

Micro injection molding Micro injection-compression molding Comparison Micro injection molding Micro injection-compression molding Molding focus Filling stage Post-filling stage Open mold temperature Lower than Tg Lower than Tg and heat balance Thick product injection Easy Hard Thin product injection MICM solves the problem of molecular orientation and residual stress, but also creates the difficulty in controlling manufacturing.

Optical Plastic Material Material in common use: Polymethyl methacrylate(PMMA), Polycarbonate(PC), Polystyrene(PS)

Optical Plastic Material PMMA Good Bad Penetrability Water absorption higher Weathering quality UV resistibility Molding Temperature lower PC Heat-resistant Molding temperature higher Chemical resistant Molding stress relief Impact resistant PS Penetrability Brittleness Chip Electric insulation

Outline Injection Molding - Micro Injection Molding - Introduction - Micro Injection Molding - Micro Injection-compression Molding - Optical Plastic Material Hot Embossing Molding - Manufacturing Parameter - Different ways from Micro Hot embossing Molding Conclusions

Micro Hot Embossing Molding If pattern’s drawing temperature is high, the product ’s surface will be coarseness.

Manufacturing Parameter To emboss high-aspect-ratio structures, in addition the following process and material properties have to be taken into account: Sidewall roughness of the embossing master:<10nm Sidewall angle : about 90degree. The chemical interface between master and substrate: add release agents. Temperature coefficients : To avoid the creation of additional forces due to the larger shrinkage. Hot embossing as a method for the fabrication of polymer high aspect ratio structures Sensors and Actuators A: Physical Volume 83, Issues 1-3, 22 May 2000, Pages 130-135 , Holger Becker1, , and Ulf Heim

Nanoimprint lithography Electron beam, RIE mold RIE Evaporation metal, acetone Si substrate <100nm

Soft lithography Soft lithography uses elastomeric imprint mode to transfer patterns to substrate. Electron beam , metal, glass mold elastomeric liquid polymer elastomeric mold

Soft lithography 1. micro-contact printing, μCP Self-assembled monolayer, SAM

Soft lithography 2. Replica molding, REM (PU)

Soft lithography 3.Microtransfer molding, μTM

Soft lithography 4.Micromolding in capillaries, MIMIC

5. solvent-assisted micromolding, SAMIM SOFT LITHOGRAPHY Younan Xia and George M. Whitesides Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Annu. Rev. Mater. Sci. 1998. 28:153–84 5. solvent-assisted micromolding, SAMIM

Step and Flash Imprint lithography The process doesn’t need large pressure in RT, and is adoptable for flipping focus disposition because mold is transparent.

Outline Injection Molding - Micro Injection Molding - Introduction - Micro Injection Molding - Micro Injection-compression Molding - Optical Plastic Material Hot Embossing Molding - Manufacturing Parameter - Different ways to Micro Hot embossing Molding Conclusions

Conclusions The methods of optical plastic devices manufacturing - micro injection molding - micro hot embossing molding The material is suitable or not depend on your purpose. Manufacturing parameter should be carefully considered.

Thanks for your kind attention

PDMS(聚二甲基矽氧烷) Polydimethylsiloxane (PDMS) is the most widely used silicon-based organic polymer, and is particularly known for its unusual rheological (or flow) properties. Its applications range from contact lenses and medical devices to elastomers, caulking, lubricating oils and heat resistant tiles. PDMS is optically clear, and is generally considered to be inert, non-toxic and non-flammable. It has been assigned CAS number 63148-62-9, and is occasionally called dimethicone. It is one of several types of silicone oil (polymerized siloxane). PDMS Provides a surface that has a low interfacial free energy and good chemical stability. It is durable. The interfacial property can be changed readily either by modifying polymers or by treating the surface with plasma, followed by the formation of SAMs.

Glass Transition Temperature In the study of polymers and their applications, it is important to understand the concept of the glass transition temperature, Tg. As the temperature of a polymer drops below Tg, it behaves in an increasingly brittle manner. As the temperature rises above the Tg, the polymer becomes more rubber-like。

Abbe number In physics and optics, the Abbe number, also known as the V-number or constringence of a transparent material, is a measure of the material's dispersion The Abbe number V of a material is defined as where nD, nF and nC are the refractive indices of the material at the wavelengths of the Fraunhofer D-, F- and C- spectral lines (589.2 nm, 486.1 nm and 656.3 nm respectively). Low dispersion materials have high values of V.

RIE Reactive ion etching (RIE) is an etching technology used in microfabrication. It uses chemically reactive plasma to remove material deposited on wafers. The plasma is generated under low pressure (vacuum) by an electromagnetic field. High-energy ions from the plasma attack the wafer surface and react with it.

SAM SAMs exhibit many attractive characteristics: ease of preparation, good stability under ambient laboratory conditions, relatively low densities of defects in the final structures. Amenability to application in controlling interfacial (physical, chemical, electrochemical, and biochemical) properties.