OPTIMIIZING THE ORGANIC SOLDERABILITY PRESERVATIVE PROCESS (OSP) FOR LEAD-FREE ASSEMBLY

摘要

There has been a paradigm shift in the last three years with respect to surface finishes. While Electroless Nickel/Immersion Gold has long dominated the lead-free surface finishing category, OSPs (organic solderability preservatives have expanded into Fine-Pitch BGA(FBGA), Flip Chip BGA(FCBGA) for mobile applications because the microelectronic packages require higher solder joint strength as well as lower cost. Unfortunately, most fabricators and assemb y firms lack sufficient understanding of the performance and process optimization requirements for successful implementation of next generation OSP. The author will detail critical temperature sensitivities of OSP materials and the impact on solderability performance. In addition, key success factors for the improvement in solderability will be discussed in detail, including surface preparation, micro-etch influence, OSP film thickness and assembly parameters.