The July 2006 Regulatory deadline for Lead-Free assembly is rapidly approaching.  The industry is seeking consensus on a standard Lead-Free Alloy for surface mount reflow process.  SAC Alloy is being adopted by many CEM/OEM(s).  However, the best PCB surface finish is still being debated.  Everyone agrees that the lowest-cost finish option is OSP; however, post reflow test problems may require that we deploy a probe-compatible alternative.   Immersion TIN is a leading candidate in Europe.   Asian PCB suppliers favor immersion SILVER but they are also capable of providing both (Sn & Ag) finishes on demand.   Even now, there are those who propose electrolytic-flash GOLD as a solution.     The goal of our test program is to cut through this haze and provide your engineering management with pertinent data on which to base their decision when choosing among the many paste and surface finish options available in the industry. 

See Solderpaste - Surface Finish HALT Evaluation for more information on testing the interaction of the surface finish with the solderpaste and process.

Thomson Lab Services is at the leading edge in the selection of the lead-free process for your application.  Reference current article on lead-free wave solder selection in STM by Thomson Lab Services (Local Copy of SMT Article - PDF format).