Title :
Reinforcing effect of coverlayers on the fatigue life of copper-Kapton flex cables
Author :
Zehnder, Alan T. ; Ingraffea, Anthony R.
Author_Institution :
Dept. of Theor. & Appl. Mech., Cornell Univ., Ithaca, NY, USA
fDate :
11/1/1995 12:00:00 AM
Abstract :
Flex cables constructed of copper sandwiched between Kapton (polyimide) fail under repeated bending due to the formation and propagation of fatigue cracks in the copper. It is observed that fatigue life of rolled-annealed copper cables with a coverlayer of Kapton is significantly higher than cables without a coverlayer. This result is explained using a fracture mechanics analysis where the Kapton layers bridge across cracks in the copper, shielding the crack from the full stresses. This retards crack growth, hence increasing fatigue life of the cables
Keywords :
bending; cables (electric); copper; fatigue; fatigue cracks; fracture mechanics; polymer films; stress analysis; Cu; Cu-Kapton flex cables; Kapton coverlayer; bending; crack growth retardation; fatigue cracks; fatigue failure; fatigue life; flexible printed wiring; fracture mechanics model; polyimide; reinforcing effect; rolled-annealed Cu cables; stress analysis; Bridge circuits; Cables; Copper; Disk drives; Fatigue; Polyimides; Printers; Stress; Transmission line matrix methods; Wiring;
Journal_Title :
Components, Packaging, and Manufacturing Technology, Part B: Advanced Packaging, IEEE Transactions on
