Grain structure of thin electrodeposited and rolled copper foils
- Gould Electronics, Eastlake, OH 44095 (United States)
- University of Kentucky, Lexington, KY 40506 (United States)
- University of Central Florida, Orlando, FL 32826 (United States)
Planar and cross-section light optical and transmission electron microscopy (TEM) and X-ray diffraction analysis have been used to characterize the technologically relevant thin copper films and foils. The grain structure and grain orientation of (i) 1-15 {mu}m deposit on the polyimide (PI) substrate (ii) 5-35 {mu}m free-standing foil and (iii) 200 {mu}m sheet prepared by the industrial scale rolling or electrodeposit process have been examined. It is shown that the rolled foil structure is highly anisotropic due to grain stretching during rolling; the pancaked grains circumscribe a dislocation cell substructure. Thermal exposure in the 423-453 K range results in full anneal softening, while initiating the polygonization of cellular substructure, the formation of new large grains by discontinuous recrystallization and the transformation of the near <111> deformation textures into the near <100> anneal textures. The texture transformation is facilitated when the oxygen content of copper is reduced from the normal 100-400 ppm level or when a low level silver ({approx}200 ppm) addition is made to copper. Depending upon the electrodeposition conditions or the nature of additives introduced in the electrolyte, it is possible to develop an electrodeposit with (a) a truly equiaxed, fine, twin-free, randomly oriented grain structure or (b) a relatively coarse grain structure, accompanied by extensive twinning, z (growth)-direction grain extension, columnar grain morphology and strong <220> crystallographic texture. Between (a) and (b), it is possible to tailor the processing to obtain a mix of fine and coarse grains, a large fraction of random orientation component (weak near <220> textures), moderate twinning, and vestiges of columnar grain morphology and z-direction grain extension. The anneal softening is not accompanied by significant grain structure modification or by texture change; somewhat above the softening temperature, an in situ grain growth ensues. For both rolled and electrodeposited (ED) foils, at 100 K or more above the softening temperature, grain growth is impeded by the foil surfaces.
- OSTI ID:
- 20748652
- Journal Information:
- Materials Characterization, Vol. 53, Issue 5; Other Information: DOI: 10.1016/j.matchar.2004.07.013; PII: S1044-5803(04)00194-9; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
- Country of Publication:
- United States
- Language:
- English
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