Astronautic PBGA (plastic ball grid array) solder joints´ reliability: under successive-high acceleration shock condition

Along with development of the astronautic industry, more and more SMT solder joints have been used in missiles, rockets and other important equipment where the environment of astronautic equipment is more serious and complex than that in normal conditions. In this paper, reliability of a kind of astronautic PBGA256 assembly sample is considered under successive-high acceleration shock conditions. During the test, the thickness of IMCs is considered and calculated by equation to compare with each other. It is found that the growth rate of the phase of Cu₆Sn₅/Cu₃Sn and Ag₃Sn is larger that other phases. So, in the final micrographs the phase of Cu₆Sn₅/Cu₃Sn and Ag₃Sn is easy to observe. After 3 hours´ successive-high acceleration (7g) shock, although the sample PBGA solder joints are still in good condition and have no obvious cracks under SEM, in the micrographs of the solder joints there are some special phenomena that are not the same as that under normal conditions or thermal fatigue load.