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Article
Publication date: 30 September 2024

Rilwan Kayode Apalowo, Muhamed Abdul Fatah Muhamed Mukhtar, Mohamad Aizat Abas and Fakhrozi Che Ani

This study aims to investigate the design configuration for an optimum solder height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly.

33

Abstract

Purpose

This study aims to investigate the design configuration for an optimum solder height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly.

Design/methodology/approach

A multiphase finite volume model is developed for reflow soldering simulations to determine the fillet height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly. Different solders, namely SAC305-x, SAC305-xNiO and SAC305-xTi, with varying percentage weight compositions of nanoparticles (x = 0 Wt.%, 0.01 Wt.%, 0.05 Wt.%, 0.10 Wt.%, 0.15 Wt.%) are investigated. A reflow soldering experiment is also conducted, and the cross-sections of the reflowed packages are examined using a High-Resolution Transmission Electron Microscope (HRTEM). The optimum design configurations (nanoparticle composition and material) for the solder fillet height are investigated using the Taguchi orthogonal array method.

Findings

Good correlations were recorded between the HRTEM micrographs and the numerical predictions of the nanoparticles' distribution in the molten solder. The numerical prediction of the fillet height also agrees with the experiment, with a maximum disparity of 5.43%. It was found that Ti nanoparticles, having the smallest density compared to NiO and, exhibit the highest buoyancy effect in the molten solder. The Taguchi analysis revealed that the nanoparticles' material factor is more significant than the Wt.% factor for an optimum fillet height. An optimum design configuration for fillet height was established as SAC 305–0.15 Wt.% Ti, corresponding to a 41.13% improvement of the plain SAC 305 solder.

Practical implications

The fillet height of solder joints greatly influences the solder joint reliability of miniaturized electronic packages. Solder joint reliability of ultra-fine capacitors can be improved using this study's findings on the optimum design configuration for the capacitor's solder fillet. The study’s findings can be practically implemented in industries such as electronics manufacturing, where enhanced solder joint reliability is critical.

Originality/value

Investigation of the optimum design configuration for reinforced SAC305 solder fillet is almost nonexistent in the literature. This study explored the optimization of fillet height of reinforced SAC305 solder joints in miniaturized capacitor assembly.

Details

Soldering & Surface Mount Technology, vol. 36 no. 5
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 15 April 2024

Rilwan Kayode Apalowo, Mohamad Aizat Abas, Fakhrozi Che Ani, Muhamed Abdul Fatah Muhamed Mukhtar and Mohamad Riduwan Ramli

This study aims to investigate the thermal fracture mechanism of moisture-preconditioned SAC305 ball grid array (BGA) solder joints subjected to multiple reflow and thermal…

125

Abstract

Purpose

This study aims to investigate the thermal fracture mechanism of moisture-preconditioned SAC305 ball grid array (BGA) solder joints subjected to multiple reflow and thermal cycling.

Design/methodology/approach

The BGA package samples are subjected to JEDEC Level 1 accelerated moisture treatment (85 °C/85%RH/168 h) with five times reflow at 270 °C. This is followed by multiple thermal cycling from 0 °C to 100 °C for 40 min per cycle, per IPC-7351B standards. For fracture investigation, the cross-sections of the samples are examined and analysed using the dye-and-pry technique and backscattered scanning electron microscopy. The packages' microstructures are characterized using an energy-dispersive X-ray spectroscopy approach. Also, the package assembly is investigated using the Darveaux numerical simulation method.

Findings

The study found that critical strain density is exhibited at the component pad/solder interface of the solder joint located at the most distant point from the axes of symmetry of the package assembly. The fracture mechanism is a crack fracture formed at the solder's exterior edges and grows across the joint's transverse section. It was established that Au content in the formed intermetallic compound greatly impacts fracture growth in the solder joint interface, with a composition above 5 Wt.% Au regarded as an unsafe level for reliability. The elongation of the crack is aided by the brittle nature of the Au-Sn interface through which the crack propagates. It is inferred that refining the solder matrix elemental compound can strengthen and improve the reliability of solder joints.

Practical implications

Inspection lead time and additional manufacturing expenses spent on investigating reliability issues in BGA solder joints can be reduced using the study's findings on understanding the solder joint fracture mechanism.

Originality/value

Limited studies exist on the thermal fracture mechanism of moisture-preconditioned BGA solder joints exposed to both multiple reflow and thermal cycling. This study applied both numerical and experimental techniques to examine the reliability issue.

Details

Soldering & Surface Mount Technology, vol. 36 no. 3
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 31 May 2024

Zuraihana Bachok, Aizat Abas, Hooi Feng Tang, Muhammad Zaim Hanif Nazarudin, Mohamad Fikri Mohd Sharif and Fakhrozi Che Ani

This study aims to investigate the influence of different solder alloy materials on passive devices during laser soldering process. Solder alloy material has been found to…

134

Abstract

Purpose

This study aims to investigate the influence of different solder alloy materials on passive devices during laser soldering process. Solder alloy material has been found to significantly influence the solder joint’s quality, such as void formation that can lead to cracks, filling time that affects productivity and fillet shape that determines the solder joint’s reliability.

Design/methodology/approach

Finite volume method (FVM)-based simulation that was validated using real laser soldering experiment is used to evaluate the effect of various solder alloy materials, including SAC305, SAC387, SAC396 and SAC405 in laser soldering. These solders are commonly used to assemble the pin-through hole (PTH) capacitor onto the printed circuit board.

Findings

The simulation results show how the void ratio, filling time and flow characteristics of different solder alloy materials affect the quality of the solder joint. The optimal solder alloy is SAC396 due to its low void ratio of 1.95%, fastest filling time (1.3 s) to fill a 98% PTH barrel and excellent flow characteristics. The results give the ideal setting for the parameters that can increase the effectiveness of the laser soldering process, which include reducing filling time from 2.2 s to less than 1.5 s while maintaining a high-quality solder joint with a void ratio of less than 2%. Industries that emphasize reliable soldering and effective joint formation gain the advantage of minimal occurrence of void formation, quick filling time and exceptional flowability offered by this solution.

Practical implications

This research is expected not only to improve solder joint reliability but also to drive advancements in laser soldering technology, supporting the development of efficient and reliable microelectronics assembly processes for future electronic devices. The optimized laser soldering material will enable the production of superior passive devices, meeting the growing demands of the electronics market for smaller, high-performance electronic products.

Originality/value

The comparison of different solder alloy materials for PTH capacitor assembly during the laser soldering process has not been reported to date. Additionally, volume of fluid numerical analysis of the quality and reliability of different solder alloy joints has never been conducted on real PTH capacitor assemblies.

Details

Soldering & Surface Mount Technology, vol. 36 no. 4
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 3 August 2023

Zuraihana Bachok, Aizat Abas, Hehgeraj A/L Raja Gobal, Norwahida Yusoff, Mohamad Riduwan Ramli, Mohamad Fikri Mohd Sharif, Fakhrozi Che Ani and Muhamed Abdul Fatah Muhamed Mukhtar

This study aims to investigate crack propagation in a moisture-preconditioned soft-termination multi-layer ceramic capacitor (MLCC) during thermal reflow process.

119

Abstract

Purpose

This study aims to investigate crack propagation in a moisture-preconditioned soft-termination multi-layer ceramic capacitor (MLCC) during thermal reflow process.

Design/methodology/approach

Experimental and extended finite element method (X-FEM) numerical analyses were used to analyse the soft-termination MLCC during thermal reflow. A cross-sectional field emission scanning electron microscope image of an actual MLCC’s crack was used to validate the accuracy of the simulation results generated in the study.

Findings

At 270°C, micro-voids between the copper-electrode and copper-epoxy layers absorbed 284.2 mm/mg3 of moisture, which generated 6.29 MPa of vapour pressure and caused a crack to propagate. Moisture that rapidly vaporises during reflow can cause stresses that exceed the adhesive/substrate interface’s adhesion strength of 6 MPa. Higher vapour pressure reduces crack development resistance. Thus, the maximum crack propagation between the copper-electrode and copper-epoxy layers at high reflow temperature was 0.077 mm. The numerical model was well-validated, as the maximum crack propagation discrepancy was 2.6%.

Practical implications

This research holds significant implications for the industry by providing valuable insights into the moisture-induced crack propagation mechanisms in soft-termination MLCCs during the reflow process. The findings can be used to optimise the design, manufacturing and assembly processes, ultimately leading to enhanced product quality, improved performance and increased reliability in various electronic applications. Moreover, while the study focused on a specific type of soft-termination MLCC in the reflow process, the methodologies and principles used in this research can be extended to other types of MLCC packages. The fundamental understanding gained from this study can be extrapolated to similar structures, enabling manufacturers to implement effective strategies for crack reduction across a wider range of MLCC applications.

Originality/value

The moisture-induced crack propagation in the soft-termination MLCC during thermal reflow process has not been reported to date. X-FEM numerical analysis on crack propagation have never been researched on the soft-termination MLCC.

Details

Soldering & Surface Mount Technology, vol. 35 no. 5
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 15 April 2024

Rilwan Kayode Apalowo, Mohamad Aizat Abas, Zuraihana Bachok, Mohamad Fikri Mohd Sharif, Fakhrozi Che Ani, Mohamad Riduwan Ramli and Muhamed Abdul Fatah bin Muhamed Mukhtar

This study aims to investigate the possible defects and their root causes in a soft-termination multilayered ceramic capacitor (MLCC) when subjected to a thermal reflow process.

64

Abstract

Purpose

This study aims to investigate the possible defects and their root causes in a soft-termination multilayered ceramic capacitor (MLCC) when subjected to a thermal reflow process.

Design/methodology/approach

Specimens of the capacitor assembly were subjected to JEDEC level 1 preconditioning (85 °C/85%RH/168 h) with 5× reflow at 270°C peak temperature. Then, they were inspected using a 2 µm scanning electron microscope to investigate the evidence of defects. The reliability test was also numerically simulated and analyzed using the extended finite element method implemented in ABAQUS.

Findings

Excellent agreements were observed between the SEM inspections and the simulation results. The findings showed evidence of discontinuities along the Cu and the Cu-epoxy layers and interfacial delamination crack at the Cu/Cu-epoxy interface. The possible root causes are thermal mismatch between the Cu and Cu-epoxy layers, moisture contamination and weak Cu/Cu-epoxy interface. The maximum crack length observed in the experimentally reflowed capacitor was measured as 75 µm, a 2.59% difference compared to the numerical prediction of 77.2 µm.

Practical implications

This work's contribution is expected to reduce the additional manufacturing cost and lead time in investigating reliability issues in MLCCs.

Originality/value

Despite the significant number of works on the reliability assessment of surface mount capacitors, work on crack growth in soft-termination MLCC is limited. Also, the combined experimental and numerical investigation of reflow-induced reliability issues in soft-termination MLCC is limited. These cited gaps are the novelties of this study.

Details

Microelectronics International, vol. 41 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 20 October 2022

Fei Chong Ng, Aizat Abas, Mohamad Riduwan Ramli, Mohamad Fikri Mohd Sharif and Fakhrozi Che Ani

This paper aims to study the interfacial delamination found in the boundary of the copper/copper-epoxy layers of a multi-layer ceramic capacitor.

118

Abstract

Purpose

This paper aims to study the interfacial delamination found in the boundary of the copper/copper-epoxy layers of a multi-layer ceramic capacitor.

Design/methodology/approach

The thermal reflow process of the capacitor assembly and the crack propagation from the initial micro voids presented in the boundary, and later manifested into delamination, were numerically simulated. Besides, the cross section of the capacitor assembly was inspected for delamination cracks and voids using a scanning electronic microscope.

Findings

Interfacial delamination in the boundary of copper/copper-epoxy layers was caused by the thermal mismatch and growth of micro voids during the thermal reflow process. The maximum deformation on the capacitor during reflow was 2.370 µm. It was found that a larger void would induce higher vicinity stress, mode I stress intensity factor, and crack elongation rate. Moreover, the crack extension increased with the exerted deformation until 0.3 µm, before saturating at the peak crack extension of around 0.078 µm.

Practical implications

The root cause of interfacial delamination issues in capacitors due to thermal reflow has been identified, and viable solutions proposed. These can eliminate the additional manufacturing cost and lead time incurred in identifying and tackling the issues; as well as benefit end-users, by promoting the electronic device reliability and performance.

Originality/value

To the best of the authors’ knowledge, the mechanism of delamination occurrence in a capacitor during has not been reported to date. The parametric variation analysis of the void size and deformation on the crack growth has never been conducted.

Details

Soldering & Surface Mount Technology, vol. 35 no. 3
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 22 September 2023

Mohamad Solehin Mohamed Sunar, Maria Abu Bakar, Atiqah A., Azman Jalar, Muhamed Abdul Fatah Muhamed Mukhtar and Fakhrozi Che Ani

This paper aims to investigate the effect of physical vapor deposition (PVD)-coated stencil wall aperture on the life span of fine-pitch stencil printing.

41

Abstract

Purpose

This paper aims to investigate the effect of physical vapor deposition (PVD)-coated stencil wall aperture on the life span of fine-pitch stencil printing.

Design/methodology/approach

The fine-pitch stencil used in this work is fabricated by electroform process and subsequently nano-coated using the PVD process. Stencil printing process was then performed to print the solder paste onto the printed circuit board (PCB) pad. The solder paste release was observed by solder paste inspection (SPI) and analyzed qualitatively and quantitatively. The printing cycle of up to 80,000 cycles was used to investigate the life span of stencil printing.

Findings

The finding shows that the performance of stencil printing in terms of solder printing quality is highly dependent on the surface roughness of the stencil aperture. PVD-coated stencil aperture can prolong the life span of stencil printing with an acceptable performance rate of about 60%.

Originality/value

Stencil printing is one of the important processes in surface mount technology to apply solder paste on the PCB. The stencil’s life span greatly depends on the type of solder paste, stencil printing cycles involved and stencil conditions such as the shape of the aperture, size and thickness of the stencil. This study will provide valuable insight into the relationship between the coated stencil wall aperture via PVD process on the life span of fine-pitch stencil printing.

Details

Soldering & Surface Mount Technology, vol. 36 no. 1
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 18 September 2019

Nurul Fadzila Zahari, Adi Irfan Che-Ani, Robiah Binti Abdul Rashid, Mas Ayu Mohd Tahir and Suzana Amat

The purpose of this paper is to reveal the significant factors that contribute to the development of the assessment framework for wheelchair accessibility to National Heritage…

685

Abstract

Purpose

The purpose of this paper is to reveal the significant factors that contribute to the development of the assessment framework for wheelchair accessibility to National Heritage Buildings.

Design/methodology/approach

A qualitative approach was conducted via semi-structured interviews and go-along interview (Accessible Audit) through selected multiple case studies to reveal the main factors that contribute to the development of the assessment framework for wheelchair users in National Heritage Buildings in Malaysia. There are four National Heritage Buildings (gazetted under National Heritage Act, 2005) selected for this research.

Findings

The findings revealed a few significant factors comprising the physical built environment, organizational behavior and structure, financial resources, and existing legislation.

Research limitations/implications

This research is limited to wheelchair users and National Heritage Buildings, which was conducted through semi-structured interviews and go-along interview (Accessible Audit).

Practical implications

This research investigates the standpoints of both the National Heritage Building operators and the wheelchair users pertaining to accessibility in National Heritage Buildings with regard to their respective roles as management and users.

Social implications

The research demonstrates the importance of social participation effects on the accessibility in National Heritage Buildings based on empirical evidence in highlighting operators’ and wheelchair users’ challenges toward enhancing their accessibility.

Originality/value

This research will be a great contribution to the development of the assessment framework for wheelchair accessibility in National Heritage Buildings in Malaysia, including accessibility for pushchair, elderly, and pregnant women.

Details

International Journal of Building Pathology and Adaptation, vol. 38 no. 2
Type: Research Article
ISSN: 2398-4708

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Article
Publication date: 6 April 2012

Chun‐Sean Lau, M.Z. Abdullah and F. Che Ani

The purpose of this paper is to develop a thermal coupling method of a ball grid array (BGA) assembly during a forced convection reflow soldering process.

776

Abstract

Purpose

The purpose of this paper is to develop a thermal coupling method of a ball grid array (BGA) assembly during a forced convection reflow soldering process.

Design/methodology/approach

The reflow oven was modeled in computational fluid dynamic (CFD) software (FLUENT 6.3.26) while the structural heating BGA package simulation was done using finite element method (FEM) software (ABAQUS 6.9). Both software applications were coupled bi‐directionally using the code coupling software MpCCI.

Findings

The convective heat transfer coefficient (h) simulated during the reflow process showed a sufficient view of the changing h in the BGA assembly of each reflow oven. The solder joints were found to experience phase change from solid to liquid during heating and liquid to solid during cooling. These phase changes were present at the melting temperature of the solder joint. The effect of the phase transition point was to cause a large range of temperature difference within the BGA assembly. This situation runs the risk of a skewing defect of components. The simulation results were compared with the experimental results and found to be in good conformity. In addition, the maximum thermal stress from simulation results was trapped in the interfaces between the solder joints and substrate, which tended to form the nucleation of initial crack.

Practical implications

The current study provides a methodology for designing a thermal profile for reflow soldering production.

Originality/value

The findings provide new guidelines for the thermal coupling method. This guideline is very useful for the accurate control of temperature distributions within components and printed circuit boards, which is one of major requirements for achieving high reliability in electronic assemblies.

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Article
Publication date: 22 June 2012

Chun‐Sean Lau, M.Z. Abdullah and F. Che Ani

The purpose of this paper is to develop thermal modelling to investigate the thermal response of sample boards (at board level) during the preheating stage of the reflow process…

1275

Abstract

Purpose

The purpose of this paper is to develop thermal modelling to investigate the thermal response of sample boards (at board level) during the preheating stage of the reflow process and to validate with experimental measurements.

Design/methodology/approach

A thermal‐coupling method that adopted the Multi‐physics Code Coupling Interface (MpCCI) was utilized. A forced‐convection reflow oven was modelled using computational fluid dynamic software (FLUENT 6.3.26), whereas structural heating at the board level was conducted using finite‐element method software (ABAQUS 6.9).

Findings

The simulation showed a complex flow pattern having characteristics of a free‐jet region, stagnation‐flow region, wall jet‐region, recirculation region and vortices. A sharp maximum heat‐transfer coefficient was detected in the stagnation region of the jet, resulting in a spatial variation of local heat transfer on a thermal profile board (TPB). This coefficient affected the temperature distribution in the TPB with different specific heat capacitances and thermal conductivity of the structure. The simulation results were in good agreement with the experimental data and analytical model. The cold region and temperature uniformity (ΔT) increased with increasing complexity of the TPB. The cold region can occur in two possible locations in the TPB. Both occurrences can be related to the flow field of the reflow oven. ΔT of the TPB decreased when the conveyor speed (v) was reduced. A suitable conveyor speed (1.0 cm/s) was determined to maintain ΔT below 10°C, which prevented the thermally critical package from overheating.

Practical implications

The paper provies a methodology for designing a thermal profile for reflow soldering production.

Originality/value

The findings provide fundamental guidelines to the thermal‐coupling method at the board and package levels, very useful for accurate control of ΔT at the board and package levels, one of the major requirements in achieving a high degree of reliability for electronic assemblies.

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