Reliability Study for Photosensitive RDL Material

In recent years, as electronic devices such as smartphones become more functional, more compact, and lower cost, many semiconductor makers are studying the packages such as WLP (Wafer Level Package) having re-distribution layer (RDL). With the miniaturization and the increase in the number of pins of a semiconductor package, the method of conduction between a semiconductor chip and an external electrode has been changed from wire connection to bump connection and RDL. And the application of a wafer coating material is also required to have higher functions from a buffer coat film to bump protection and an interlayer insulating film for RDL. Further, in recent years, in addition to the purpose of avoiding the performance deterioration of the semiconductor device due to the high-temperature treatment, a packaging material having low heat resistance is sometimes used in the FOWLP, and therefore, the wafer coating material is required to lower temperature curable. We have studied the reliability of the RDL package with various RDL photosensitive materials.