The shrinking solder dimensions greatly impact the reliability of devices and increase entire failure modes. Limited solder volumes can be consumed completely and transformed into intermetallic compound (IMC) microbumps. Microvoids surface when microbumps are formed and may be attributed to a mismatch of the thermal expansion coefficient between the constituents. After thermal aging at 150 degrees C, the stress induced by the growth of IMCs relaxes and enhances propagation of the cracks along the middle of the bumps. The brittle nature of the IMC showed minimal resistance to cracks and incurred a failure mode. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671391]
