Isı Bilimi ve Tekniği Dergisi, 33, 1, 43-53, 2013 J. of Thermal Science and Technology ©2013 TIBTD Printed in Turkey ISSN 1300-3615 FSI STUDY OF THE EFFECT OF AIR INLET/OUTLET ARRANGEMENTS ON THE RELIABILITY AND COOLING PERFORMANCES OF FLEXIBLE PRINTED CIRCUIT BOARD ELECTRONICS W.C. LEONG*, M.Z. ABDULLAH, C.Y. KHOR and H.J. TONY TAN Universiti Sains Malaysia,School of Mechanical Engineering, Engineering Campus, 14300 Nibong Tebal, Penang, Malaysia, *weichiat2008@hotmail.com, Phone: +60 124913898 (Geliş Tarihi: 23.06.2011 Kabul Tarihi: 18.08.2011) Abstract Abstract: Flexible printed circuit boards (FPCB) are being used extensively in current electronics devices because of its reduced thickness and ability to bend. Physical reliability and cooling capability are the main concern in the development of FPCB electronics. Therefore, present study investigates the reliability and cooling performance of FPCB, for different air inlet/outlet arrangements, in fan sucking mode. These inlet/outlet arrangements are found to have prominent effect on the performance of FPCB. The FSI (fluid-structure interaction) study is performed using the fluid flow solver FLUENT and structural solver ABAQUS at real-time online coupled by Mesh-based Parallel Code Coupling Interface (MpCCI). In addition, the present study also explores the effect of mass flow rates on the performance of FPCB. As the flow rate increases, the cooling capability is enhanced, but deterioration is observed on the reliability. Keywords: FSI; flexible printed circuit board; inlet/outlet arrangement; physical reliability; cooling capability. HAVA GİRİŞ/ÇIKIŞ KONUMLARININ ESNEK DEVRE KARTLARININ GÜVENİLİRLİĞİ VE SOĞUTMA PERFORMANSINA ETKİSİNİN İNCELENMESİ İÇİN AKE ÇALIŞMASI Özet: Esnek baskılı devre kartları (EBDK), azaltılmış kalınlığı ve esnekliği nedeni ile günümüz elektronik cihazlarında yoğun olarak kullanılmaktadır. Fiziksel güvenilirli k ve soğutulabilme özelliği EBDK elektronik katların geliştirilmesini etkileyen temel unsurlardır. Bundan dolayı, bu çalışmada fan emme durumunda değişik hava giriş/çıkış konumlarının EBDK’nın güvenilirliğine ve soğutulmasına etkisi incelenmiştir. Giriş/çıkış düzenlemelerinin EBDK performansı üzerinde önemli etkileri olduğu bulunmuştur. AKE (akışkan-katı etkileşimi) çalışması, gerçek zamanlı çevrimiçi Mesh-based Parallel Code Coupling Interface (MpCCI) ile akışkan akışı çözücüsü FLUENT ve yapısal çözücü ABACUS birlikte kullanılarak yapılmıştır. Ek olarak, kütlesel debinin EBDK’nın performansına etkileride incelenmiştir. Debi artarken, soğutma kapasitesinin artığı fakat güvenilirliğin azaldığı gözlemlenmiştir. Anahtar Kelimeler: AKE, Esnek baskılı devre kartı, giriş/çıkış düzenlemesi, fiziksel güvenilirlik, soğutma kapasitesi. INTRODUCTION Flexible printed circuit boards (FPCB) can be an alternative to rigid printed circuit board (PCB). It has been proven advantageous in some applications because of its excellent flexibility, twistability and light weight. In the majority of systems with moderate heat dissipation, fans are the most common devices used for cooling purpose. The fan flows can induce pressure on the electronic components and subsequently cause deflection on the board. Compared with rigid board, FPCB experiences much larger deformation during operation and also exhibits different cooling capability. Therefore, durability and long-term performance are the primary concern in the application of FPCB. Many researchers have focused on this area; a review of previous works, which build a background for the current study, is presented as follows. Azar and Russell (1990) experimentally studied the impact of component layout and geometry on flow distribution on a circuit pack. They found that the flow in electronic enclosures was highly three dimensional, and the location and orientation of components with large aspect ratio would significantly affect the flow distribution. Similar study was reported by Lee and Mahalingam (1993), who used a computational fluid dynamics (CFD) tool to evaluate the velocity and the temperature fields of air flow in a computer system enclosure, and correlated the predictions with real time experiments. Dealing with the component-PCB heat transfer, Rodgers and co-workers (Eveloy et al., 2000; Rodgers et al., 2003a; Rodgers et al., 2003b) performed numerical and experimental works to assess the predictive accuracy of CFD tools for the thermal analysis of electronic systems, in natural and forced convection modes. The