An accelerated method for characterization of bi-material interfaces in microelectronic packages under cyclic loading conditions

In this paper, an accelerated and cost-effective characterization method for bi-material interfaces under cyclic loading using a Miniaturized Cyclic Mixed-mode Bending (MCMB) test setup is presented. The Modified Single Leg Bending (MSLB) samples are acquired directly from production-line Thin Quad Flat Package (TQFP) which provide a mixed-mode I + II loading condition. Under sub-critical cyclic loading, crack was found to occur at the polymer-metal interface. The crack length is measured using three methods: (i) in-situ measurements using microscope (ii) gray scale correlation method (iii) numerical method. The crack growth rate was found to have a power-law dependence on the strain Energy Release Rate (ERR) range. In addition influence of plasma cleaning on interfacial adhesion properties namely, crack initiation and propagation is discussed.