Deep X-ray lithography and low-stress high-hardness electroplating technologies for the micro structure
| Autor: | Min-Chieh Chou, 周敏傑 |
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| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 This investigation studied the deep X-ray lithography and the Ni-based alloy electroplating technologies for the low-stress, high-hardness and high-aspect-ratio micro structures. How the exposure dosage and developing temperature affected the development and how the composition of the plating bath and current density affected the composition, metallurgical microstructure, residual stress and hardness of Ni-Co and Ni-P-SiC deposits were discussed. The results of low-aspect-ratio X-ray lithography reveal that, with ultrasonic agitation, the developing rate of PMMA in developer is linearly proportional to the logarithm of the exposure dosage, and also to the developed depth. The codeposition of Ni-Co alloy becomes more anomalous while the cobalt content in the deposit is over 58.3 wt.%. When the cobalt content is about 27 wt.%, the hardness is maximum of Hv 580. By adding the stress reducer, the residual stress can be adjusted to 0.012 kg/mm2 with the smallest grain size of 50 nm in the deposit. The results of the Ni-P-SiC electroplating reveal that increasing current density and SiC concentration in the bath can increase the SiC content in the deposit. Adding SiC into Ni-P alloy matrix significantly reduces the residual stress in the deposit and consequently eliminates the surface crack of the deposit. SiC also greatly lowers the phosphorus content in the deposit, and then increases the hardness to a maximum of Hv 770 as the mass fraction of phosphorus in the deposit is approximately 3.66 %. At higher phosphorus contents, the deposits are associated only with (111)Ni preferred oriented grains. When the phosphorus content is close to or below 3.66 %, the structure becomes more random and is accompanied by the presence of (200)Ni and (220)Ni planes. The microstructure of Ni-P-SiC composite deposit with 3.5 wt.% phosphorus is composed of fine columnar fcc polycrystalline, which are perpendicular to the surface of substrate. The diameter of the columar grain is about 20 nm. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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