Surface mount power converters

Application boards on which on-board power supplies are used are populated substantially with surface mount components. These are typically assembled with conventional single or double sided SMT (surface mount technology) reflow processes. The few remaining PTH (plated through hole) components need to be manually placed and soldered either by hand or by a process such as selective wave, selective jet or robotic soldering. The complexity of many modern application boards in terms of layer count and component density, combined with the desire to eliminate these additional process steps is leading to a desire for the elimination of the remaining PTH components of which the DC-DC converter is the most conspicuous. This paper deals with many of the challenges faced when designing and using a state of the art, surface mountable, high density power-supply which must be treated as a single surface mount component. These issues include interconnect design, joint strength and reliability, electrical and thermal conductivity, as well as manufacturing considerations such as pick and place compatibility, inspection and rework.