“…This could be because of the fact that their heat capacities/thermal conductivities differ, which will result in their uneven heating up (Kim et al , 2015). The thermal conductivity of an FR4 substrate is very low and varies from 0.25 W/m·K (Mauney and Qian, 2007) to 0.35 W/m·K (Lin et al , 2013), whereas for copper, the values are much higher 355 W/m·K (Mauney and Qian, 2007) or 398 W/m·K (Lin et al , 2013). However, the specific heat capacity of copper is around 385 J/kg·K, whereas for laminate it is 880 J/kg·K (Wong, 2010) − 1,210 J/kg·K (Backryd and Elden, 2006).…”