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Proceedings Paper

Growth and crystallinity of electroformed nickel structures
Author(s): Shih-Chia Chang; John Edens
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Paper Abstract

Nickel structures were electroformed from a commercially available nickel sulfamate bath. The plating molds were made of thick photoresist (approximately 20 micrometers) and delineated by a UV lithographic method. For mold cavities with very small aspect ratios (minimum planar dimension/mold thickness), the deposition rate is higher for those with smaller feature sizes than those with larger feature sizes. For mold cavities with large aspect ratios, no such correlation was observed. X-ray and transmission electron microscopy results show that the electroformed nickel is polycrystalline and in columnar form. For current density less than or equal to 8 mA/cm2, the nickel deposits orient preferably with <220> crystallographic direction normal to the substrate surface. For current density greater than or equal to 12 mA/cm+2), the nickel cantilevers tend to curl downward, and the nickel deposits orient preferably with <200> crystallographic direction normal to the substrate surface. There are only minor differences in the relative intensities of the (111), (200) and (220) x-ray peaks of the nickel deposits electroplated on gold, copper and chromium, implying that the effect of the plating base material on the nickel structure is minimal. The relative intensities of the (111), (200) and (220) x-ray peaks vary throughout the thickness of nickel structures. However, the variations are random, and therefore no correlation between the crystallinity and the built-in stress can be established at this point.

Paper Details

Date Published: 5 September 1997
PDF: 10 pages
Proc. SPIE 3223, Micromachining and Microfabrication Process Technology III, (5 September 1997); doi: 10.1117/12.284470
Show Author Affiliations
Shih-Chia Chang, General Motors Research and Development Ctr. (United States)
John Edens, General Motors Research and Development Ctr. (United States)


Published in SPIE Proceedings Vol. 3223:
Micromachining and Microfabrication Process Technology III
Shih-Chia Chang; Stella W. Pang, Editor(s)

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