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Since the 1970s, the sustainable development was developed from science and environmental crusade. Since then, there were many programs done in the field but not named as “Sustainable Development.” The environments have affected because of the process of the development which was noticed by the world community. Malaysia has made a commitment to the 2030 Agenda in September 2015 for the future of mother earth. Despite the increasing attention toward sustainable development and circular economy across the world, understanding of the potential sustainability synergy among developing countries remains sluggish. This chapter therefore briefly discusses the development of circular economy within developed and developing countries. The chapter then narrowed the discussion toward Malaysian practices of the circular economy. Malaysia also recorded among the countries that faced waste management issues in Asia. The detailed discussion includes Malaysian acceptance and initiatives in reaching a circular economy within the past years, present, and future. The discussion surrounds the circular economy practiced by Malaysian industrial players as well as government's initiatives in encouraging and educating Malaysian toward embracing the idea of circular economy and sustainable consumption. As most countries embrace green technologies, Malaysia has taken proactive steps toward adopting green technology. Among the four main policy priorities are energy, environment, economy, and social, the key to green technology in driving the country's economy while promoting sustainable development. In fact, the major economic drivers of the Malaysian economy involve industrial activities such as palm oil, mining, and manufacturing, which are now beginning to take steps toward the development of green technology development. The application of green technology can provide a balance between economic development and environmental preservation as well as solutions to climate change issues. The initiative aims to make Malaysia one of the best countries in the world with sustainable economic growth, innovation, and prosperous citizens by 2050.

Mosques are built with dome-shaped ceilings for communal worship with common architectural styles worldwide for prayer. Since the acoustics of worship buildings are just as significant as their aesthetics, they should enhance people’s sense of hearing. This study evaluates the speech intelligibility of a small mosque with multiple domes to determine the space acoustic conditions.

The investigation involved extensive literature reviews to collect relevant data to model the case study. The Enhanced Acoustics Simulator for Engineers (EASE) software program was used to integrate critical parameters such as the absorption coefficient of materials, dome shapes and the number of domes in the simulation. The study employed speech intelligibility parameters such as C50, S.T.I. and %ALcons to assess the acoustic conditions. The assessment model was validated through statistical analysis and a paired t-test.

The study discovered that varying shapes of the multiple domes showed no significant impact on speech intelligibility. However, different multiple domes materials resulted in significant disparities in speech intelligibility. Applying high-absorption materials in multiple dome designs achieved the most effective acoustic performance. Except for C50 in some circumstances and receiver positions, all other alternatives met the optimal value for overall speech intelligibility because the sound was not sufficiently diffused early on, suggesting that the early reflection sounds were either weak or insufficient.

This study not only helps to determine the multiple-dome effect on mosque acoustics but also empowers archaeoacoustics and historic conservation by documenting these significant places of worship. The findings advocate using high-absorption materials in multiple dome designs and offer practical insight into mosque design material selection. By enhancing the understanding of the acoustic conditions in small-scale mosques, this study equips architects, engineers and builders with the knowledge to create spaces prioritizing speech clarity and intelligibility.

In line with the recent development of flip-chip reliability and underfill process, this paper aims to comprehensively investigate the effect of different hourglass shape solder joint on underfill encapsulation process by mean of experimental and numerical method.

Lattice Boltzmann method (LBM) numerical was used for the three-dimensional simulation of underfill process. The effects of ball grid arrays (BGA) encapsulation process in terms of filling time of the fluid were investigated. Experiments were then carried out to validate the simulation results.

Hourglass shape solder joint has shown the shortest filling time for underfill process compared to truncated sphere. The underfill flow obtained from both simulation and experimental results are found to be in good agreement for the BGA model studied. The findings have also shown that the filling time of Hourglass 2 with parabolic shape gives faster filling time compared to the Hourglass 1 with hemisphere angle due to bigger cross-sectional area of void between the solder joints.

This paper provides reliable insights to the effect of hourglass shape BGA on the encapsulation process that will benefit future development of BGA packages.

LBM numerical method was implemented in this research to study the flow behaviour of an encapsulation process in term of filling time of hourglass shape BGA. To date, no research has been found to simulate the hourglass shape BGA using LBM.

The purpose of this study is to investigate the effect of the adhesive force and density ratio using lattice Boltzmann method (LBM) during underfill process.

To deal with complex flow in underfill process, a framework is proposed to improve the lattice Boltzmann equation. The fluid flows with different density ratio and bump arrangement in underfill are simulated by the incorporated Carnahan–Starling (CS) equation of state (EOS). The numerical study conducted by finite volume method (FVM) and experimental results are also presented in each case at the different filling percentage for verification and validation purpose.

The numerical result is compared well with those acquired experimentally. Small discrepancy is detected in their flow profile. It was found that the adhesive force between fluid and solid was affected by the density ratio of the fluids and solder bump configuration. LBM has shown better adhesive force effect phenomenon on underfill process compared to FVM. LBM also demonstrated as a better tool to study the fluid flow in the underfill process.

This study provides a basis and insights into the impact of adhesive force and density ratio to the underfill process that will be advancing the future design of flip chip package. This study also provides superior guidelines, and the knowledge of how adhesive force is affected by flip chip package structure.

This study proposes the method to predict the adhesive force and density ratio effect for underfill flow in flip chip package. In addition, the proposed method has a good performance in representing the adhesive force during the underfill simulation for its natural physical basic. This study develops understanding of flow problems to attain high reliability for electronic assemblies.

This paper presents the synthesizing of carbon-carbon (CC) composites by preformed yarn (PY) method, by varying the percentage of carbon fiber volume. The PY used is carbon fiber bundle surrounded by coke and pitch which is enclosed in nylon-6. Three types of samples with fiber weight fractions of 30%, 40% and 50% respectively, are fabricated and tested. In each case, the PY is chopped and filled into a die of required shape and hot pressed at 600°C to get the carbonized composite. To obtain the graphitic structure, the specimen is heat treated at 1800°C followed by soaking for two hours. Further, one cycle pitch impregnation is done by hot isostatic pressing, to eliminate the voids. The characteristics such as hardness, compressive strength, creep, density and oxidation resistance are studied. It is observed that, as the carbon fiber percentage increases the properties also improved, provided sintering is done at fairly higher temperatures. The superiority of the new class of CC composites made by the proposed PY technique over those obtained by the conventional methods is also demonstrated.

The purpose of this study is to investigate the dynamics of capillary underfill flow (CUF) in flip-chip packaging, particularly in a multi-chip configuration. The study aims to understand how various parameters, such as chip-to-chip spacing (S12), chip thickness (tc) and others, affect the underfill flow process. By using computational fluid dynamics (CFD) simulations and experimental studies, the goal is to provide insights into understanding the dynamics of CUF in heterogeneous electronic packaging.

The paper introduces a CFD analysis and experimental study on CUF in a multi-chip configuration, aiming to understand underfill flow dynamics. A 3D geometry models of multi-chip arrangement are created using computer-aided design (CAD) software. After that, the CAD models are meshed and simulated in Ansys Fluent using incompressible and non-Newtonian fluid properties. The study maintains S12 of 2.86 and tc of 22.29 between experimental and simulation data for results validation. Next, a various of S12 values (1.14, 2.86, 5.71, 8.57, 14.29 and 20) which focus on tc of 22.29 have been investigated. Further studies have been conduct using S12 of 5.71 and tc of 8.00, 14.29 and 22.29.

Results show a strong correlation between simulation and experiment which validate the correctness and robustness of simulation. Further parameter’s studies using simulation for various of S12 indicated that higher S12 values lead to faster flow. This effect is due to large underfill weight from reservoir able to flow into S12 region which contributed to higher mass momentum movement. Furthermore, the effect of various of tc shows that the thicker the chip the faster the underfill to flow in S12 region.

The intentional exclusion of solder bump pattern arrangements from the experiment and simulation may limit the study's ability to fully understand the impact of solder bump patterns on underfill flow. Therefore, more parameters can be investigated such as solder bump pattern, underfill weight and dispense pattern in the future using CFD.

The manuscript provides a comprehensive examination of the contributions of CFD to the advancement of knowledge regarding CUF phenomena in heterogeneous electronic packaging assemblies. Moreover, it delineates the utilization of CFD methodologies to assess the influence of chip-to-chip spacing (S12) and the thickness of the chip (tc) on the underfill flow characteristics.

This paper fulfills an identified need of computational fluid dynamics method to study capillary underfill flow dynamics in heterogenous electronic packaging.

The aim of this study is to investigate the effects of offset angle in wave soldering by using thermal fluid structure interaction modeling with experimental validation.

The authors used a thermal coupling approach that adopted mesh-based parallel code coupling interface between finite volume-and finite element-based software (ABAQUS). A 3D single pin-through-hole (PTH) connector with five offset angles (0 to 20°) on a printed circuit board (PCB) was built and meshed by using computational fluid dynamics preprocessing software called GAMBIT. An implicit volume of fluid technique with a second-order upwind scheme was also applied to track the flow front of solder material (Sn63Pb37) when passing through the solder pot during wave soldering. The structural solver and ABAQUS analyzed the temperature distribution, displacement and von Mises stress of the PTH connector. The predicted results were validated by the experimental solder profile.

The simulation revealed that the PTH offset angle had a significant effect on the filling of molten solder through the PCB. The 0° angle yielded the best filling profile, filling time, lowest displacement and thermal stress. The simulation result was similar to the experimental result.

This study provides a better understanding of the process control in wave soldering for PCB assembly.

This study provides fundamental guidelines and references for the thermal coupling method to address reliability issues during wave soldering. It also enhances understanding of capillary flow and PTH joint issues to achieve high reliability in PCB assembly industries.

This paper aims to study the filling progression of underfill flow and void formation during the flip-chip encapsulation process.

A new parameter of filling progression that relates volume fraction filled to filling displacement was formulated analytically. Another indicative parameter of filling efficiency was also introduced to quantify the voiding fraction in filling progression. Additionally, the underfill process on different flip-chips based on the past experiments was numerically simulated.

All findings were well-validated with reference to the past experimental results, in terms of quantitative filling progression and qualitative flow profiles. The volume fraction filled increases monotonically with the filling displacement and thus the filling time. As the underfill fluid advances, the size of the void decreases while the filling efficiency increases. Furthermore, the void formed during the underfilling flow stage was caused by the accelerated contact line jump at the bump entrance.

The filling progression enabled manufacturers to forecast the underfill flow front, as it advances through the flip-chip. Moreover, filling progression and filling efficiency could provide quantitative insights for the determination of void formations at any filling stages. The voiding formation mechanism enables the prompt formulation of countermeasures.

Both the filling progression and filling efficiency are new indicative parameters in quantifying the performance of the filling process while considering the reliability defects such as incomplete filling and voiding.

This paper aims to present new analytical model for the filling times prediction in flip-chip underfill encapsulation process that is based on the surface energetic for post-bump flow.

The current model was formulated based on the modified regional segregation approach that consists of bump and post-bump regions. Both the expansion flow and the subsequent bumpless flow as integrated in the post-bump region were modelled considering the surface energy–work balance.

Upon validated with the past underfill experiment, the current model has the lowest root mean square deviation of 4.94 s and maximum individual deviation of 26.07%, upon compared to the six other past analytical models. Additionally, the current analytically predicted flow isolines at post-bump region are in line with the experimental observation. Furthermore, the current analytical filling times in post-bump region are in better consensus with the experimental times as compared to the previous model. Therefore, this model is regarded as an improvised version of the past filling time models.

The proposed analytical model enables the filling time determination for flip-chip underfill process at higher accuracy, while providing more precise and realistic post-bump flow visualization. This model could benefit the future underfill process enhancement and package design optimization works, to resolve the productivity issue of prolonged filling process.

The analytical underfill studies are scarce, with only seven independent analytical filling time models being developed to date. In particular, the expansion flow of detachment jump was being considered in only two previous works. Nonetheless, to the best of the authors’ knowledge, there is no analytical model that considered the surface energies during the underfill flow or based on its energy–work balance. Instead, the previous modelling on post-bump flow was based on either kinematic or geometrical that is coupled with major assumptions.

This paper aims to present experimental and finite volume method (FVM)-based simulation studies on the scaling effect on the capillary contact angle and entrant pressure for a three-dimensional encapsulation process of ball-grid array (BGA).

With the development of various sizes of BGA packages, the scaling effect of BGA model on capillary underfill (CUF) process is investigated together with the influences of different industrial standard solder bump arrangements and dispensing methods used as case study.

The experimental results agree well to the simulation findings with minimal deviation in filling time and similar flow front profiles for all setups. The results revealed that the capillary contact angle of flow front decreases in scale-up model with larger gap height observed and lengthens the encapsulation process. Statistical correlation studies are conducted and accurate regression equations are obtained to relate the gap height to the completion filling time and contact angle. CUF threshold capillary pressures were computed based on Leverett-J function and found to be increasing with the scale size of the package.

These statistical data provide accurate insights into the impact of BGA’s scale sizes to the CUF process that will be benefiting the future design of BGA package. This study provided electronic designers with profound understanding on the scaling effect in CUF process of BGA, which may be extended to the future development of miniature-sized BGA and multi-stack device.

This study relates the flow behaviour of encapsulant to its capillary contact angle and Leverett-J pressure threshold, in the CUF process of different BGA and dispensing conditions. To date, no research has been found to predict the threshold pressure on the gap between the chip and substrate.