TY - JOUR
T1 - Improvement of form accuracy and surface integrity of Si-HDPE hybrid micro-lens arrays in press molding
AU - Abdul Manaf, Ahmad Rosli
AU - Yan, Jiwang
N1 - Funding Information:
The authors would like to thank Mitsubishi Chemical Corporation and Global Wafers Japan Co. Ltd, Japan for providing HDPE and Si samples and technical data. We also thank Toshiba Machine Co. Ltd, Shizuoka, Japan, for technical assistance in the pressing molding experiments using the GMP–311 V machine, and Dr. Tsunetoshi Sugiyama (Light for Wave Co., Japan) for his support during the lens design. This work has been partially supported by Keio University KLL Research Grant (000017) for Ph.D. Program for 2015 Academic Year, and Keio University Doctorate Student Grant-in-Aid Program 2015.
Publisher Copyright:
© 2016 Elsevier Inc.
Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 2017/1/1
Y1 - 2017/1/1
N2 - Press molding of silicon (Si)/high-density polyethylene (HDPE) composite is an important technology for producing thin hybrid infrared (IR) optics with microstructures. In this research, Si-HDPE hybrid micro-lens arrays were press molded under various conditions, and the form accuracy and surface integrity of the molded lenses were evaluated. Air trapping occurs inside the micro-lens cavities during molding in a non-vacuum environment, which leads to severe surface defects. To investigate the air trapping phenomenon, a new in-situ observation system was developed which enables real-time direct observation of the molding process. From the in-situ observations, it was found that air traps were formed among the HDPE pellets during melting, and an increase in the pressing force will increase the pressure of the trapped air, forming trenches on the lens surface. The trapped air also impacts the mold coating, causing trench formation on the coating surface. To minimize air trapping, the molding temperature, and pressing force must be strictly controlled. By performing press molding in a vacuum environment, trench formation was completely eliminated. Moreover, polymer shrinkage compensation was performed to improve the lens form accuracy.
AB - Press molding of silicon (Si)/high-density polyethylene (HDPE) composite is an important technology for producing thin hybrid infrared (IR) optics with microstructures. In this research, Si-HDPE hybrid micro-lens arrays were press molded under various conditions, and the form accuracy and surface integrity of the molded lenses were evaluated. Air trapping occurs inside the micro-lens cavities during molding in a non-vacuum environment, which leads to severe surface defects. To investigate the air trapping phenomenon, a new in-situ observation system was developed which enables real-time direct observation of the molding process. From the in-situ observations, it was found that air traps were formed among the HDPE pellets during melting, and an increase in the pressing force will increase the pressure of the trapped air, forming trenches on the lens surface. The trapped air also impacts the mold coating, causing trench formation on the coating surface. To minimize air trapping, the molding temperature, and pressing force must be strictly controlled. By performing press molding in a vacuum environment, trench formation was completely eliminated. Moreover, polymer shrinkage compensation was performed to improve the lens form accuracy.
KW - Hybrid optics
KW - Infrared lens
KW - Lens array
KW - Microstructure
KW - Press molding
UR - http://www.scopus.com/inward/record.url?scp=84995921511&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84995921511&partnerID=8YFLogxK
U2 - 10.1016/j.precisioneng.2016.10.002
DO - 10.1016/j.precisioneng.2016.10.002
M3 - Article
AN - SCOPUS:84995921511
SN - 0141-6359
VL - 47
SP - 469
EP - 479
JO - Precision Engineering
JF - Precision Engineering
ER -