The impact of packaging on the reliability of flip chip solder bonded devices

The authors report on the assessment of flip-chip solder-joint reliability for a hybrid device assembly in which a zirconium-titanium-stannate (ZTS) dielectric ceramic chip is flip-chip-bonded to a silicon circuit. This device assembly was subjected to severe thermal cycling testing involving up to 2000 cycles from -55 to +125 degrees C. A range of device solder-bond geometries and chip passivation structures was investigated, with devices packaged in both hermetic and nonhermetic enclosures. The results showed that flip-chip solder bonds can be extremely reliable under such tests, with no failures being detected in devices that were hermetically packaged. Fatigue failures were observed in nonhermetically packaged devices. Extrapolation to likely operating conditions predicted field lifetimes of between 15 and 300 yr.>