http://irplus.eng.usm.my:8080/ir_plus/viewContributorPage.action;jsessionid=A98ED840157D1EB4DDFE2566A045ACC7?personNameId=5262 Contributor Page for: Chong Hooi Lim EngLib USM http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action;jsessionid=A98ED840157D1EB4DDFE2566A045ACC7?institutionalItemVersionId=6683 Teknologi elektronik dan mikroelektronik yang berkembang pantas meningkatkan permintaan terhadap peranti elektronik yang fleksibel dan ringan. Papan Litar Tercetak Fleksibel (FPCB) yang digunakan untuk menggantikan Papan Litar Tercetak Tegar (RPCB) dilengkapi dengan ciri-ciri tersebut. Walaubagaimanapun, ciri-ciri lembut yang terdapat pada FPCB menghadapi pesongan (δ) yang tidak diperlukan dan tegasan yang hadir daripada aliran dan haba yang dijana daripada komponen-komponen semasa operasi. Di dalam penyelidikan yang dijalankan, kesan haba dan aliran terhadap FPCB dengan pakej Jaringan Grid Bola (BGA) telah berganding secara setemu di dalam simulasi untuk mengkaji kesannya terhadap FPCB. Kesan-kesan aliran telah dikaji pada permulaan penyelidikan, diikuti dengan penambahan sumber haba terhadap pakej BGA. Disamping itu, pemindahan haba yang 24 % lebih tinggi pada FPCB telah ditunjukkan apabila dibandingkan dengan RPCB. Beberapa faktor parametrik telah dikaji termasuklah halaju aliran (v) (1 – 5 m/s), 1 - 4 pakej BGA yang dilampirkan, sumber kuasa (0 – 0.213 W) yang dikenakan pada pakej BGA, saiz FPCB (80mm2 – 140mm2) dan jarak antara pakej BGA (15 mm – 45 mm). Disamping itu, kecekapan pemindahan haba (h) telah ditambah sebagai tindak balas terhadap kajian pemindahan dalam kes yang melibatkan sumber haba. Kemudian v, δ dan h telah dinormalkan kepada nombor Reynolds (Re), δ/panjang FPCB (L) dan nombor Nusselt (􀴤􀜰􀴤􀴤􀝑􀴤􀴤 ) yang tidak berdimensi. Kebanyakan faktor-faktor parametrik telah dijumpai amat mempengaruhi tegasan δ/L dan 􀴤􀜰􀴤􀴤􀝑􀴤􀴤 . Tambahan pula, pengoptimuman telah dijalankan melalui kaedah permukaan tindakbalas (RSM) bagi menyediakan pendekatan rekabentuk yang berasaskan faktor-faktor dalam kajian awal untuk kepentingan jurutera dan perekabentuk FPCB. Berdasarkan penemuan penyelidikan, pengaruh aliran lebih tinggi terhadap tindak balas apabila sumber haba rendah. Sebaliknya, pengaruh haba lebih tinggi daripada pengaruh aliran apabila sumber haba tinggi. Selain itu, korelasi empirik 􀴤􀜰􀴤􀴤􀝑􀴤􀴤 , Re, nombor Prandtl (Pr) dan δ/L telah berjaya ditemukan, di mana pengaruh yang paling tinggi ialah Re diikuti oleh Pr dan δ/L. Di dalam penyelidikan terkini, di bawah pengaruh aliran dan sumber haba, δ/L, tegasan dan 􀴤􀜰􀴤􀴤􀝑􀴤􀴤 yang tertinggi boleh mencecah 0.0043, 8.69 MPa and 85.54. Oleh itu, adalah amat penting untuk mengambilkira aspek haba bersama pengaruh aliran untuk mendapatkan ciri-ciri FPCB bersama pakej BGA semasa operasi. Kejayaan simulasi ini boleh membantu kajian tentang ciri-ciri fleksibel substrat dengan komponen yang beroperasi di bawah pengaruh aliran. __________________________________________________________________________ The rapid development of electronic and microelectronic technology increases the demands for electronics device with flexible and light weight capability. Flexible printed circuit board (FPCB) which can be used to replace rigid printed circuit board (RPCB) is well equipped with those features. However, the soft feature of FPCB poses unwanted deflection (δ) and stress from the flow and heat generated by the operating components. In present research, thermal and flow effects on FPCB with attached ball grid array (BGA) packages have been investigated where the numerical simulation with coupled of flow and thermal effects concurrently has been successfully developed in the simulation. The effects of flow are studied at the initial stage of the research, followed by the addition of heat source to the BGA packages. The experimental work with actual attached ball grid array (BGA) packages was carried out to verify and validate the results. Findings show that better heat transfer performance on FPCB with an average 24 % higher than RPCB. Several parametric factors are explored including flow velocities (v) (1 – 5 m/s), 1 - 4 number of BGA packages attached, power supplied to the BGA packages (0 – 0.213 W), size of FPCB (80mm2 – 140mm2) and distance between BGA packages (15 mm – 45 mm). The heat transfer coefficient (h) has been added into the responses to study the heat transfer in the cases that involved heat source. Later on, v, δ and h had been normalized into dimensionless Reynolds number (Re), δ/length of FPCB (L) and Nusselt number (􀴤􀜰􀴤􀴤􀝑􀴤􀴤 ), respectively. Most the parametric factors were found to be significantly affected the δ/L, stress and 􀴤􀜰􀴤􀴤􀝑􀴤􀴤 . Optimization is then carried out by response surface methodology (RSM) to provide the design approaches based on those factors in present study for the interests of FPCB designers or engineers. Based on the results and findings, the flow has significant effect on the responses when thermal power is low. On the other hand, the thermal effect is higher than flow when thermal power is high. Besides, empirical correlation equations of Re, Prandtl number (Pr), δ/L and 􀴤􀜰􀴤􀴤􀝑􀴤􀴤 has been established, in which the highest effect is Re, followed by Pr and δ/L. In present research, under the influences of flow and thermal power supplied, the highest δ/L, stress and 􀴤􀜰􀴤􀴤􀝑􀴤􀴤 could reach 0.0043, 8.69 MPa and 85.54, respectively. Therefore, it is important to consider thermal effect together with flow influences for understanding the characteristic of FPCB attached with BGA under operating condition. With the successful development of thermal-mechanicalfluid- structure interaction numerical coupling method, in which thermal and flow effects have been considered simultaneously could help to study flexible substrate characteristic under operating condition and flow environment which is closer to real life scenario. Tue, 25 Aug 2020 09:32:20 +0800 institutional_item_version_id:6683