Solder Fillet Height Criteria for Surface Mounted Chip Components

Abstract

An evaluation has been performed to determine the effects of solder joint fillet height variations of blue tantalum chip capacitors (CWR06) when exposed to thermal shock. Capacitors were soldered to ceramic multilayer interconnect boards (MIBs) used on U.S. Navy Format D standard electronic modules (SEM). Three fillet heights were tested; 100 percent of the capacitor height, 50 percent of the capacitor height, and a minimum amount to wet the bottom edges and face of the components. Results showed that components with 50 percent and minimum wetting solder disclosed no detrimental conditions whereas those with the 100 percent fillet height showed cracks in the MIB material during and at the end of 125 cycles of thermal shock. Accordingly, it is concluded that the maximum desired solder joint fillet height for chip capacitors mounted on ceramic substrates is fifty percent (50 percent) of the component height. This conclusion agrees with research on ceramic chip components mounted on organic substrates in which the desirable condition is to have low solder volumes.