Flip chip (FC) has been used to replace wire bond due to its better performance. The 1st interconnection in FC plays an important role in terms of reliability study. Au/Cu stud bump capped with Sn tends to have Kirkendall void in the joint which can cause open circuit. This paper focuses on depth analysis on solderless chip bumping by using only Cu stud bump in the chip on chip (CoC) ball grid array (BGA) package. High temperature storage 150 °C has been applied on package and the result was compared with those the use of Au stud bump capped with Sn. The result shows that Cu stud bump has a better reliability in term of electrical resistance compared with Au stud bump capped with Sn. Therefore, solderless chip bumping has the potential to replace Au stud bump capped with Sn for FC BGA package.
