Effects of cleaning process on the reliability of ultra-fine gap for 3D package

Fine pitch interconnection is a key stream to accommodate increased I/O applications. This enabling technology provides more I/O in shrunken die area, and hence high density interconnection. However, the majority of studies are focusing on the solder material and failure mode by using various intermetallic compounds (IMC) formation. In order to improve the reliability of the mirco-interconnects, it is indispensable to remove flux residues in the center of the package as clean as possible through washing process to avoid the delamiantions along the interfaces between the u-joint and the underfill. Spin cleaning replace conventional water jet to challenge ultra-fine gap for 3D package. As a result, cleaning procedures with different chemical solvent will major impact to cleaning situation. Several DOEs have been constructed for solvent to increase BGA reliability by optimizing cleaning process. A comparison of flux cleaning process technologies for chip and wafer level interconnection were be discussed. This paper shows methods and comparison of the conveyer, spin clean, water jet for chip level, and spin cleaning for wafer level. In addition, multi reflow (at time zero, 1×, 3×) and thermal cycling test were performed for underfill delamiantion. The detailed influence of u-joint with various bump density on the hydrodynamics was investigated and discussed.