European Microelectronics Packaging Conference September 2015, Friedrichshafen, Germany www.empc2015.org Effects of Component Stand-off Height on Reliability of Solder Joints in Assembled Electronic Component Jude E. Njoku l , Sabuj Mallik* l , Raj Bhatti l , Emeka H. Amalu 2 , B. Ogunsem ? 1 Faculty of Engineering and Science, University of Oreenwich, UK 2 School of Science and Engineering, University of Wolverhampton, UK. * Corresponding Author: s.mallik@gre.ac.uk, +44 (0)1634 883243 Abstract The structural performance of electronic devices depends immensely on the standof height of the components used to assemble them. The component standof height (CSH) of electronic assemblies can be varied either by changing the settings of the reflow profile parameters or by vaying the diameter of bond pad on the printed circuit board (PCB). The continued desire by electronic manufacturing industries to improve the reliabiliy of their devices has driven researchers to seek in-depth understanding of the contribution of CSH on the integriy of solder joints in these assemblies. This is coupled with the fact that there is no industy standard for CS, for electronic components. This investigation studies the efect of CSH on the shear strength and failure mechanism uf assembled Ball Grid Array (BGA) electronic components. Five diff erent CSHs were achieved by vaying the bond pads on the PCB while keeping the reflow proile parameters constant. These test vehicles were subjected to shear stress using aDage 4000 series bond teste. The results obtained demonstrate that the dff erent vehicles produce dff erent load proiles and their shear strength increases with decrease in their CSH. It was found that the mechanics of failure of the specimen is both by crack propagation at the interface between solder bulk and the intermetallic layer; and by pad lfting. These indings would be useful to benchmark the CHS for BGAs, for their optimal mechanical reliabiliy. 1 Introduction The electronics manufacturing industries across the globe serve as one of the most important and dynamic industries. Electronic products not only satisfy the consumer market needs but also play a crucial role in high-reliability and safety-critical applications II automotive, aerospace and energy sectors. These products directly or indirectly affect people's lives. Examples of electronic products include but are not limited to mobile phones, personal computers, electronic organisers, television, super computers, electronic control units in vehicles and aircrafts. This paper looks into the reliability of these electronic devices, with a special focus on solder joint component standoff height. The surface mount electronic assembly and packaging technology is one of key technologies that ensure that the manufacture of these electronic products is possible. In surface mount technology (SMT), 'soldering' is the primary means of forming interconnection between electronic components (such as the ball grid arrays (BOAs), diode, transistors, capacitors and other integrated circuits (ICs)) and printed circuit board (PCB). For more than 30 years, lead-free solders dominated as the soldering material. However, owing to the environment and human health hazard, several legislations aganst the use and disposal of lead-based electronic products have been adapted in Japan, Europe ISBN 978-0-9568086-2-2 and some parts of the United States [I]. As a result, electronics manufacturers are forced to replace lead based solders with new lead-free solders. Reliability of these new lead-free solders is a real concen and has been the focus of many research studies [2 - 5]. There is an ever-increasing demand for electronic portable devices, coupled with growing trend towards miniaturization, increased functionality and high power density. In order to match these demands many area array packages are developed, such as Ball Orid Array (BOA), Chip-Scale Package (CSP) and Flip-Chip. Among these BOAs are now widely used as high performance miniature package and offer some distinct advantages over other surface mount packages. BOAs are mounted with the substrates at its bottom surface using solder balls. As there are no leads, BOAs have reduced co-planarity issues and are easier to handle [2]. Other important benefits of BOA include self-centering of solder balls during placement, higher ball pitch than the leaded flat packages, higher heat dissipation from the package to the substrate and also better electrical performance due to low induction leads. Component standoff height (CSH) represents the solder joint height between the component and substrate. BOA is prone to warpage during surface mount assembly, which produces higher CSH at the coners than the centre of the package. It is therefore, important to evaluate the impact of CSH on solder joint reliability. Indeed, CSH has been the focus of many recent studies. © IMAPS/EMPC2015