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Title: Mechanical fatigue of thin copper foil

Abstract

The electrodeposited and the rolled 12 to 35 {micro}m thick copper foils are subjected to the bending/unbending strain-controlled flex fatigue over a wide range of strain amplitudes. The fatigue life is associated with an increase in electrical resistance of the specimen beyond a preassigned threshold. For each foil type, in the rolled or as-deposited as well as in the (recrystallization-like) annealed conditions, the inverse Coffin-Manson (C-M) relationship between strain amplitude ({Delta}{epsilon}/2) and fatigue life (N{sub f}) is established in the high {Delta}{epsilon}/2 (low N{sub f}) and the low {Delta}{epsilon}/2 (high N{sub f}) regimes. The N{sub f}, {Delta}{epsilon}/2, and C-M slopes (c,b) are utilized to calculate the cyclic strain hardening (n{prime}) and fatigue ductility (D{sub f}) parameters. It is shown that for a given foil thickness, an universal relationship exists between D{sub f} and the strength ({sigma}) normalized fatigue life (N{sub f}/{sigma}). The propagation of fatigue crack through the foil thickness and across the sample width is related to the unique fine grain structure for each foil type: pancaked grains for the rolled foil and equiaxed grains for the electrodeposited foil. The fatal failure corresponds to convergence of the through-thickness and the across-the-width fatigue cracks. The variations in (i) electrical resistance,more » (ii) mid-thickness microhardness and grain structure and (iii) dislocation configurations with fatigue are monitored. Except for a small but significant fatigue induced softening (or hardening), nonconvincing evidence of strain localization (and the associated dislocation configurations generally observed for the bulk samples) has been found.« less

Authors:
; ;
Publication Date:
Research Org.:
Gould Electronics, Eastlake, OH (US)
OSTI Identifier:
20000141
Alternate Identifier(s):
OSTI ID: 20000141
Resource Type:
Journal Article
Journal Name:
Journal of Electronic Materials
Additional Journal Information:
Journal Volume: 28; Journal Issue: 9; Conference: 1999 TMS Annual Meeting, San Diego, CA (US), 03/02/1999--03/03/1999; Other Information: PBD: Sep 1999; Journal ID: ISSN 0361-5235
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; FATIGUE; COPPER; FOILS; ELECTRODEPOSITION; ANNEALING; STRAINS; CRACKS; DISLOCATIONS

Citation Formats

Merchant, H.D., Minor, M.G., and Liu, Y.L. Mechanical fatigue of thin copper foil. United States: N. p., 1999. Web. doi:10.1007/s11664-999-0176-x.
Merchant, H.D., Minor, M.G., & Liu, Y.L. Mechanical fatigue of thin copper foil. United States. doi:10.1007/s11664-999-0176-x.
Merchant, H.D., Minor, M.G., and Liu, Y.L. Wed . "Mechanical fatigue of thin copper foil". United States. doi:10.1007/s11664-999-0176-x.
@article{osti_20000141,
title = {Mechanical fatigue of thin copper foil},
author = {Merchant, H.D. and Minor, M.G. and Liu, Y.L.},
abstractNote = {The electrodeposited and the rolled 12 to 35 {micro}m thick copper foils are subjected to the bending/unbending strain-controlled flex fatigue over a wide range of strain amplitudes. The fatigue life is associated with an increase in electrical resistance of the specimen beyond a preassigned threshold. For each foil type, in the rolled or as-deposited as well as in the (recrystallization-like) annealed conditions, the inverse Coffin-Manson (C-M) relationship between strain amplitude ({Delta}{epsilon}/2) and fatigue life (N{sub f}) is established in the high {Delta}{epsilon}/2 (low N{sub f}) and the low {Delta}{epsilon}/2 (high N{sub f}) regimes. The N{sub f}, {Delta}{epsilon}/2, and C-M slopes (c,b) are utilized to calculate the cyclic strain hardening (n{prime}) and fatigue ductility (D{sub f}) parameters. It is shown that for a given foil thickness, an universal relationship exists between D{sub f} and the strength ({sigma}) normalized fatigue life (N{sub f}/{sigma}). The propagation of fatigue crack through the foil thickness and across the sample width is related to the unique fine grain structure for each foil type: pancaked grains for the rolled foil and equiaxed grains for the electrodeposited foil. The fatal failure corresponds to convergence of the through-thickness and the across-the-width fatigue cracks. The variations in (i) electrical resistance, (ii) mid-thickness microhardness and grain structure and (iii) dislocation configurations with fatigue are monitored. Except for a small but significant fatigue induced softening (or hardening), nonconvincing evidence of strain localization (and the associated dislocation configurations generally observed for the bulk samples) has been found.},
doi = {10.1007/s11664-999-0176-x},
journal = {Journal of Electronic Materials},
issn = {0361-5235},
number = 9,
volume = 28,
place = {United States},
year = {1999},
month = {9}
}