Chong Hooi Lim, M.Z. Abdullah, I. Abdul Azid, C.Y. Khor, M.S. Abdul Aziz and M.H.H. Ishaik
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…
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 (δ/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), δ/L and Nu have been established, in which the highest effect is of Re, followed by Pr and δ/L. The δ/L and
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.
Details
Keywords
Chong Hooi Lim, Mohd Zulkifly Abdullah, Ishak Abdul Aziz, Chu Yee Khor and Mohd Sharizal Abdul Aziz
This study aims to investigate the interaction of independent variables [Reynolds number (Re), thermal power and the number of ball grid array (BGA) packages] and the relation of…
Abstract
Purpose
This study aims to investigate the interaction of independent variables [Reynolds number (Re), thermal power and the number of ball grid array (BGA) packages] and the relation of the variables with the responses [Nusselt number ((Nu) ¯ ), deflection/FPCB’s length (d/L) and von Mises stress]. The airflow and thermal effects were considered for optimizing the Re of various numbers of BGA packages with thermal power attached on flexible printed circuit board (FPCB) for optimum cooling performance with least deflection and stress by using the response surface method (RSM).
Design/methodology/approach
Flow and thermal effects on FPCB with heat source generated in the BGA packages have been examined in the simulation. The interactive relationship between factors (i.e. Re, thermal power and number of BGA packages) and responses (i.e. deflection over FPCB length ratio, stress and average Nusselt number) were analysed using analysis of variance. RSM was used to optimize the Re for the different number of BGA packages attached to the FPCB.
Findings
It is important to understand the behaviour of FPCB when exposed to both flow and thermal effects simultaneously under the operating conditions. Maximum d/L and von Misses stress were significantly affected by all parametric factors whilst (Nu)¯ is significantly affected by Re and thermal power. Optimized Re for 1–3 BGA packages with maximum thermal power applied has been identified as 21,364, 23,858 and 29,367, respectively.
Practical implications
This analysis offers a better interpretation of the parameter control in FPCB with optimized Re for the use of force convection electronic cooling. Optimal Re could be used as a reference in the thermal management aspect in designing the BGA package.
Originality/value
This research presents the parameters’ effects on the reliability and heat transfer in FPCB design. It also presents a method to optimize Re for the different number of BGA packages attached to increase the reliability in FPCB’s design.