| Peel strength of Cr/polyimde interfaces was measured on Cu/Cr/polyimide structures using T-peel test. Peel strength of Cr/BPDA-PDA interfaces decreased with increasing the thickness of Cu/Cr metal films to a critical value, and then increased with further increasing metal film thickness. When the thickness of Cu/Cr films was below a critical value, plastic bending of metal films mainly occurred during T-peel test. With metal films thicker than a critical thickness, however, plastic bending of polyimide films has been observed. A critical thickness of metal films, where transition from metal bending to polyimide bending occurred, became thinner with lower yield strength of metal films and with thicker polyimide film. Without depending on the plastic bending of metal or polyimide films, peel strength increased with increasing the peeling angle during T-peel test. |
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