Process, Design and Material Factors for Voiding Control for Thermally Demanding Applications
Authors: Amit Patel, Matthew Siebenhuhner, Gyan Dutt, Ranjit Pandher, Mitch Holtzer, T.W. Mok Company: Alpha Assembly Solutions Date Published: 9/17/2017
Abstract: Solder voiding is a common phenomenon across all semiconductor packaging and electronic board assemblies. Voids are a troublesome defect in assemblies created using surface mount technology. Voids can interfere with electric signals, can be insulators when heat dissipation is required, and they can also be the source of crack propagation and early failure of an assembly when occurring near the pad surface. The acceptable levels for voiding vary upon on the end-application and environment it’s used in. In the case of thermally demanding harsh environment applications such as automotive and outdoor LED lighting void control is required in order to optimize the performance and extend the lifetime of these components. The lower the voiding on these thermal and electrical pads, the better the connection to the PCB and subsequent layers. There are many factors that influence void frequency and size. This study focuses on several process, design and materials selection considerations which control or potentially reduce voiding to meet industry and end-market acceptance criteria. More specifically, package design, reflow profiles, and solder paste chemistry are discussed in the form of application studies. Commercial mid-power PLCC and high-power ceramic LED packages on aluminum metal core PCBs additionally BGA, DPak, and MLF on FR4 PBCs were used for these case studies.