The relationship between microstructural characteristics and mechanical properties of electrodeposited copper foils for PCB applications
| Autor: | Ding-Shiang Wang, 王鼎翔 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 In this study, the microstructural characteristics and mechanical properties of the electro-deposited Cu foils with different preferred orientations were investigated. Three types of foils were studied, including HTE (High temperature elongation), MP (Middle profile) and VLP(Very low profile). Observation results indicate that the columnar grains of the HTE、MP and VLP-A samples with (220) preferred orientation were arranged with a fan-like appearance. The (200) oriented grains of samples VLP-B and VLP-C were more equi-axed. Sample VLP-D showed a strong (111) preferred orientation and possessed fine but elongated columnar grains grown along the thru-thinkness direction. There existed a close relationship between preferred orientation and nanoindentation responses. The elastic modulus in decreasing order was (111), (220) and then (200) oriented foils. Foils with different preferred orientations also behaved differently in tensile properties at room temperature, 150oC and 250oC. In general, (220)-oriented foils had better ductility, and the MP samples with (220) preferred orientation exhibited the best performance in tensile strength at different temperatures. Worthy of notice is, jerky flows appeared in the tensile stress-strain curves tested at 150oC and 250oC. Our experimental results demonstrate that the jerky flow resulted from the combined effect of dynamic recrystallization (DRX) and dynamic strain aging (DSA). The dynamic recrystallization occurred and the DSC analytical results verify that the electro-deposited Cu foils possessed much lower recrystallization temperatures than the bulk copper. Moreover, the dynamic strain aging could be ascribed to the dissolved Zn in the Cu matrix diffused from the heat resistant coating. The foils VLP-B, C, D with violet serrations in tensile curves were strengthened at 250oC by DSA. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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