An evaluation of effects of molding compound and substrate material properties on reliability of Cu wire BGA components

The transitions to copper (Cu) from gold (Au) bond wires is occurring for an increasingly broader range of semiconductor components. For ball grid array (BGA) packages, key packaging materials including molding compound and substrate all need to be re-evaluated as they may interact with Cu wire bond differently from Au wires and introduce new failure mechanisms. In this work, we investigate the impact of molding compound chemistry and halogen content of substrate on the reliability performance of an organic BGA package. For the molding compound, two material properties, pH level and C1-concentration are varied and a total of 9 formulations are generated. For substrates, a high-halogen substrate and a Halogen Free substrate are evaluated. Two types of acceleration tests, HTS (High Temperature Storage) test and biased-HAST (Highly Accelerated Stress Testing) are performed on the components. The effects of molding compound pH/C1-levels and substrate halogen content on the failure rates will be discussed. Additionally, analytical results on the failed components using FIB (Focus Ion Beam), SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), and EDX (Energy Dispersive X-ray) will be reported. The reliability testing and analytical results will demonstrate the importance of controlling packaging material properties and provide guidelines for the selection of these materials. For high-reliability and mission-critical electronic systems, improved and better-controlled packaging material formulations will be needed to ensure the long-term reliability of components using Cu bond wires.