Finite element modeling of thermal fatigue and damage of solder joints in a ceramic ball grid array package

A nonlinear finite element model is presented for analyzing the cyclic and thermal fatigue loading and for viscoplastic damage characterization of the lead-tin (Pb-Sn) solder joints in a ceramic ball grid array (CBGA) surface mount, package. An approach using a Delta is an element of(eq)(in)-modified Coffin-Manson equation is proposed to estimate the fatigue life of the solder joints, The Delta is an element of(in)(eq) represents a saturated equivalent inelastic strain range as determined by the finite element model, The present study shows that the predictied fatigue life and the associated damage mechanism of the solder joint agree reasonably well with the test data for the 18, 25, and 32 mm CBGA packages run at a cyclic temperature load of 0 degrees C/100 degrees C with a frequency of 1.5 cycles per hour. Analysis also shows that a preferred failure site is expected to occur in and around the Pb37-Sn63 solder attachment of tile solder joint A time-dependent (creep induced) damage mechanism is found to be more pronounced than the time-independent (plastic deformation) mechanism.