โ Scribed by Nihal Sinnadurai; Kenneth Cooper; John Woodhouse
No coin nor oath required. For personal study only.
With the advent of surface-mounting technology, an apparent problem that has received much attention is the potential failure of solder joints between microcomponents and printed circuit boards. One tequnique used to assess such joints is to subject the assemblies to thermal cycling over a wide temperature range. The validity of the method has, however, not been proven and there are serious reservations about its relevance when considering: the mechanical and thermal properties of solders and other materials associated with the assemblies, the temperature excursions and their rates likely to be encountered in real life, and the more probable problems due to intermittent power dissipation in surface-mounted components.
Thus, thermal cycling may prove to be useful only in process development and quality testing. In the event, if the object is to subject the joint to cycling strain, then a more rapid and therefore more efficient test has been devised whereby mechanical cycling is employed to simulate the effects of thermal cycling.
๐ SIMILAR VOLUMES
The surface mount assembly industry, especially the contract manufacturing segment, is currently undergoing a transition from an assembly process that requires a cleaning step to one that does not. In addition, maximization of yields is critical to the contract assembly environment. This paper addre