Hydraulic bulge test of electrodeposited copper foil

The 18 mu m to 72 mu m thick commercial electrodeposited copper foils GR 1 and GR 3, the experimental foil TCAM and the commercial rolled foil GR 8 ar e tested in bulge and in tension at temperatures up to 300 degrees C. Utili zing the bulge data, pressure and deflection at rupture, the through-thickn ess fracture stress (sigma(t)) and fracture strain (epsilon(t)) are calcula ted and compared to the corresponding average tensile values sigma(av) and epsilon(av). The effects of foil thickness, orifice size and test temperatu re on sigma(t) and epsilon(t) are characterized. In many instances approxim ately one-to-one correspondence exists between sigma(t), epsilon(t) and sig ma(av), epsilon(av); there are, however, significant exceptions due to text ure hardening, thermal embrittlement and grain pancaking. The extent of emb rittlement is greatest for the GR 1 foil, increasing with the foil thicknes s; it is virtually non-existent for the (rolled) GR 8 foil. Thermal anneali ng overshadows the embrittlement effects for the GR 3 foil. The TCAM foil e mbrittles modestly but displays poor resistance to thinning at room tempera ture; however, the resistance improves markedly with increasing test temper ature.