In a recent SMT007 survey, we asked the following question: " What are your challenges when it comes to solder paste selection/qualification?" Here are just a few of the replies, slightly edited for clarity.
Jon Ashton, Vergent Products: “The IPC/J-STD test methods are applied to all new pastes. This leads to all manufacturers saying that their material ‘meets the requirements’ but the rest of their pitch is all marketing. There needs to be a simple battery of tests, using a simple (cheap) PCB test vehicle, that can qualify a given paste in a specific process. This also applies to cleaning residues. Finally, the old pastes are still available. There is no reason to disturb an existing qualified process with a paste change. As such, they hang on forever to the long tail.”
Allen Bennink, VAL Engineering Sciences Inc.: "Usage of end product, and powder size and chemistry (of metal and flux carrier)."
Bob Rooks, Trak Microwave: “ROHS, age of components, and halogen-free RMA flux.”