HIGH QUALITY REFLOW SOLDERING WITH VAPOR PHASE THE NEW APPROACH OF VAPOR PHASE TECHNOLOGY

摘要

Vapor Phase Soldering is known today as one of the provenrnreflow soldering methods, however it is still seen beingrnexotic to many users and also the discussions on benefitsrnand shortfalls are not necessarily considering today′srntechnology.rnThe Vapor Phase process was reinvented in the 90srnovercoming the challenges of the original process. Based onrnthis renewed Vapor Phase procedure, various new machinesrnwere developed. Vapor Phase Soldering now offers newrnfeatures, in particular when it comes to lead free soldering.rnThe main advantages of a state of the art Vapor Phasernsystem are low process temperatures, freely adjustablerntemperature gradients and profiles, automatically controlledrntime above liquidus and a perfectly inert process atmospherernwithout using cost intensive protective gas measures.rnThe task in reflow soldering is to evenly heat up PCBrnboards to a level that soldering can be accomplished even onrnsockets or in the center of large BGA’s but at the same timernto be sure that nothing is overheated or delaminated. Sornespecially for lead free soldering the process windowrnbecomes pretty small. With Vapor Phase Soldering evenrnFR4 boards, double sided densely packed, can be solderedrnreliably and with no danger of overheating since thernmaximum board temperature is physically limited to thernvapor temperature (e.g. 230-235°C for lead-free SnAgCu).rnBecause of it′s perfect inert atmosphere the wetting withrnlead free solder paste in a Vapor Phase oven is the bestrnpossible wetting today. A thorough temperature gradientrncontrol in Vapor Phase becomes crucial as soon asrntombstoning is becoming immanent in the process. Like inrnconvection reflow, the sensitivity of tombstoning isrnsignificantly influenced by the temperature profile.rnThe advantages of the Vapor Phase heat transfer inrncombination with new machines and options offer anrnexcellent tool for easy and defect free reflow soldering,rnindependent whether lead free or leaded solders are used.