SMT ASSEMBLY CHALLENGES AND PROVEN SOLUTIONS FOR IMPROVING YIELDS

摘要

Surface mount technology (SMT) assemblies are getting more complex as advancements in the areas of printed circuit board (PCB) manufacturing and component design become more main stream. Most SMT manufacturing processes have to now be capable of building "hybrid" assemblies, which contain both previous generation technology and more cutting edge technological advancements. Increasing SMT assembly yields is a must, but it is getting more and more difficult to just maintain yields, let alone increase them, as new technologies continue to be introduced. There are many variables in the SMT assembly process. Some, like SMT assembly equipment, process parameters, and personnel, are directly controlled by the SMT assembly company. Some, like PCB layout, PCB fabrication, component availability, component substitution, and solder paste stencil fabrication, are provided either by the end customer or through suppliers. There are many times where everything in the SMT assembly process is within specifications, but SMT defects still occur and yields are not as expected. What challenges can those in SMT assembly expect to face when building these more advanced assemblies? What can be done, if anything, to reduce SMT defects and improve process yields? This paper will present the most common SMT yield challenges being confronted today, discuss their root cause, and then provide solutions that are proven, repeatable, and economical.