Reliability testing of electrically conductive joints made of sintered nano silver

The studies are focused on sintered nano silver as a possible replacement or an alternative material for current interface materials used inside electronic packages (i.e. flip chip solder joints, gold wire bonds, die-attach materials, thermal interface materials) as well as used for interconnections of embedded components, 3D stacked assembly etc. Durability of sintered nano silver joints of SMD 1206 chip jumpers assembled on printed circuit boards (PCBs) has been the main object of the study. Nano silver interconnections had been sintered on copper pads covered by electroless nickel immersion gold coating (ENIG). Two different nano silver pastes have been applied and compared. The pastes varied in silver concentration and size of particles. After sintering process the interconnections were subjected to random vibration. During reliability test time to failure (cracks of interconnections) was measured by dedicated event detector. Reliability of interconnections made of both test materials was estimated based on comparative Weibull analysis. Failure mode was confirmed by the results of X-Ray nanofocus computed tomography.