Effects of Solder Voiding on the Reliability and Thermal Characteristics of Quad Flatpack No-lead (QFN) Components

Test vehicles were assembled with Quad Flatpack No-lead (QFN) components and subjected to thermal cycle conditioning. Components were inspected to measure voiding within the component thermal pads for different solder alloys and different configurations of microvias in the test boards. The resulting distributions of voiding showed that lead-free solders had substantially more voiding and that the presence of microvias increased the voids in components with tin-lead solder. Thermal modeling was used to assess whether the presence of these voids would adversely affect the thermal characteristics of the QFN. This modeling indicates that voiding in the range measured in this study would have little impact on the component's thermal resistance.