Heat transfer and deformation analysis of flexible printed circuit board under thermal and flow effects Chong Hooi Lim Faculty of Engineering and Green Technology, Universiti Tunku Abdul Rahman, Kampar, Malaysia and School of Mechanical Engineering, Universiti Sains Malaysia – Engineering Campus Seri Ampangan, Nibong Tebal, Malaysia M.Z. Abdullah School of Mechanical Engineering, Universiti Sains Malaysia – Engineering Campus Seri Ampangan, Nibong Tebal, Malaysia I. Abdul Azid Mechanical Section, Universiti Kuala Lumpur, Selangor, Malaysia C.Y. Khor Faculty of Engineering Technology, Universiti Malaysia Perlis, Arau, Malaysia M.S. Abdul Aziz School of Mechanical Engineering, Universiti Sains Malaysia – Engineering Campus Seri Ampangan, Nibong Tebal, Malaysia, and M.H.H. Ishaik School of Aerospace Engineering, Universiti Sains Malaysia – Engineering Campus Seri Ampangan, Nibong Tebal, Malaysia Abstract Purpose – The purpose of this study is to investigate heat transfer and deformation of flexible printed circuit board (FPCB) under thermal and flow effects by using fluid structure interaction. This study simulate the electronic cooling process when electronic devices are generating heat during operation at FPCB under force convection. Design/methodology/approach – The thermal and flow effects on FPCB with attached ball grid array (BGA) packages have been investigated in the simulation. Effects of Reynolds number (Re), number of BGA packages attached, power supplied to the BGA packages and size of FPCB were studied. The responses in the present study are the deflection/length of FPCB (d /L) and Nusselt number (Nu). Findings – It is important to consider both thermal and flow effects at the same time for understanding the characteristic of FPCB attached with BGA under operating condition. Empirical correlation equations of Re, Prandtl number (Pr), d /L and Nu have been established, in which the highest effect is of Re, followed by Pr and d /L. The d /L and Nu were found to be significantly affected by most of the parametric factors. Practical implications – This study provides a better understanding of the process control in FPCB assembly. Originality/value – This study provides fundamental guidelines and references for the thermal coupling modelling to address reliability issues in FPCB design. It also increases the understanding of FPCB and BGA joint issues to achieve high reliability in microelectronic design. Keywords CFD, Flexible printed circuit board, BGA, Electronic cooling, Empirical correlation equations Paper type Research paper Nomenclature a = Area of FPCB; b = Height of component; H = Wind tunnel height; h = Heat transfer coefficient; h = Average heat transfer coefficient; k = Thermal conductivity; L = Length; l = Width of component; Nu = Local Nusselt number; Nu = Average Nusselt number; Pr = Prandtl number; Re = Reynolds number; U = Linear displacement; UR = Rotational displacement; and v; v ! = Velocity. The current issue and full text archive of this journal is available on Emerald Insight at: https://www.emerald.com/insight/0305-6120.htm Circuit World © Emerald Publishing Limited [ISSN 0305-6120] [DOI 10.1108/CW-02-2020-0016] The authors would like to thank Universiti Sains Malaysia, Penang, Malaysia, for the financial support through Research University Grant (RUI)1001/PMEKANIK/8014072. Received 4 February 2020 Revised 11 May 2020 Accepted 16 June 2020