Solder interconnect reliability under drop impact loading conditions using High-speed Cold Bump Pull
Abstract The use of microelectronic components in mobile appliances is constantly increasing. Appliances like mobile phones, PDA’s and navigation systems contain more and more functionality and smaller microelectronic components. Dropping an appliance during its lifespan is very common and the product is required to survive this. The drop however, generates significant forces and vibrations on the internal assembly of the product. The performance of a microelectronic component under drop conditions has thus become an important reliability parameter. Assessing the solder interconnect quality by means of drop impact testing, as standardized by e.g. JEDEC, during normal production requires considerable amounts of time and effort. Besides this, the repeatability of the drop impact test is low and introduces elaborate and time-consuming analysis of the results after testing. Already many researchers have investigated new test techniques capable of replacing the drop impact test. In the CBP test the solder bump is pulled in vertical direction from the die using a small pair of jaws. In this test, by varying the pull speed several different strain rates can be applied to the solder bump. In our research a correlation between the drop impact test and Cold Bump Pull test is investigated. This can be divided into three parts. First by investigating the Cold Bump Pull test apparatus for uncontrolled parameters that might introduce a bias or spread in the results. Secondly by means of modeling the Cold Bump Pull test to investigate solder bump deformation and solder bump loading during pull off. Finally in a comparison the differences and similarities between the two tests are briefly discussed and some observations concerning the solder joint performance are presented.