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Solder joint integrity has long been recognized as a key issue affecting the reliability of integrated circuit packages. In this study, both experimental and finite element simulation methods were used to characterize the mechanical performance and fracture behavior of micro-scale ball grid array (BGA) structure Cu/Sn–3.0Ag–0.5Cu/Cu solder joints w...
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... values of 16 lm and 37 lm, respectively. Sn-3.0Ag-0.5Cu (simplified as SAC305) solder balls with different diameters were used to prepare BGA structure Cu/ Sn-3.0Ag-0.5Cu/Cu (i.e., Cu/SAC305/Cu) solder joint samples by twice reflow soldering process with a typical ramp-soak-spike (RSS) curve offered by a BGA rework machine (RD-300), as shown in Fig. 1. The peak temperature was 250 °C and the dwell time at 250 °C was 30 s. The measured heating rate from 120 to 250 °C was 1.5 °C/s and the cooling rate from 250 °C to 150 °C was $2.3 °C/s [17]. Fig. 2(a) shows an as-reflowed single BGA solder joint. Solder joint samples were prepared with three different standoff heights (h) of 500, 300 ...
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... FE simulation results indicate that the shear strength of solder joints increases with decreasing standoff height, the experimental shear strength data of the micro-scale joints show a parabolic trend with the standoff height (see Fig. 10, where each point is the average value (±1 standard deviation) of twelve sam- ples). Clearly, the average shear strength increases with decreasing h from 500 to 300 lm, but it decreases further when h is reduced from 300 to 100 lm. These results may be explained that with the standoff height decreasing from 300 to 100 lm, the solder ...
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... Crack driving force at the SAC305/IMC interface of BGA joints Fig. 11 shows the fracture mode of a BGA joint with a standoff height of 500 lm aged at 125 °C for 1000 h. Clearly, fracture may happen at the interface of SAC305/IMC after long-time thermal aging. This is mainly because the bonding strength of the SAC305/IMC interface has been decreased after aging for long-time [34]. Thus, the crack ...
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... l 1 and l 2 are shear moduli of the Cu 6 Sn 5 layer and SAC305, respectively, which can be calculated according to Eq. (14), in which (E 1 , E 2 ) and (m 1 , m 2 ) are elastic modulus and Poisson's ratio of Cu 6 Sn 5 and SAC305, respectively, and j i = (3 À 4m i ) (i = 1, 2). The oscillatory index e is given by Eq. (15): Fig. 12. SIFs and total strain energy release rates at the crack tip at the SAC305/IMC interface of BGA joints with different standoff heights: (a) SIFs; and (b) total strain energy release ...
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... property of SAC305 and ensure the validity of the calculated results of SIFs at the SAC305/IMC interface based on interfacial fracture mechanics, a loading shear stress of 11.05 MPa (i.e., F = 2 N, see Fig. 4) was applied with a quasi-static loading rate of 1 N/min to investigate the interfacial mechanical behavior of the BGA solder joints. Fig. 12(a) shows that K I is larger than K II when h > 200 lm, which means failure at the interface occurs by opening (i.e., mode I), while K II is larger than K I when h 6 200 lm, failure is by shearing (mode II). Hence, the fracture mode may change from the opening mode to the shearing mode when h is decreased. Further, both SIFs and G I (see ...
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... Fig. 12(a) shows that K I is larger than K II when h > 200 lm, which means failure at the interface occurs by opening (i.e., mode I), while K II is larger than K I when h 6 200 lm, failure is by shearing (mode II). Hence, the fracture mode may change from the opening mode to the shearing mode when h is decreased. Further, both SIFs and G I (see Fig. 12(b)) at the interface crack increase significantly with increasing standoff height h, and this explains why interface failure is more prone to occur in the BGA joints with large h after long-time thermal aging. Fig. 13 shows the brittle fracture in the IMC layer of BGA joints after isothermal aging at 150 °C for 1200 h. Here, cracks form ...
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... the fracture mode may change from the opening mode to the shearing mode when h is decreased. Further, both SIFs and G I (see Fig. 12(b)) at the interface crack increase significantly with increasing standoff height h, and this explains why interface failure is more prone to occur in the BGA joints with large h after long-time thermal aging. Fig. 13 shows the brittle fracture in the IMC layer of BGA joints after isothermal aging at 150 °C for 1200 h. Here, cracks form at the interface of Cu 6 Sn/Cu 3 Sn according to the chemical composition and element distribution results analyzed by electron probe micro- analysis and shown in Figs. 13(b) and (d).The interface between two IMCs ...
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... BGA joints with large h after long-time thermal aging. Fig. 13 shows the brittle fracture in the IMC layer of BGA joints after isothermal aging at 150 °C for 1200 h. Here, cracks form at the interface of Cu 6 Sn/Cu 3 Sn according to the chemical composition and element distribution results analyzed by electron probe micro- analysis and shown in Figs. 13(b) and (d).The interface between two IMCs with a layered structure often serves as an easy path for brittle crack propagation [41]. Besides, the formation of Cu 3 Sn requires more Cu atoms than Cu 6 Sn 5 , excessive growth of Cu 3 Sn promotes the formation and growth of Kirkendal voids in the Cu 3 Sn layer and at the Cu 3 Sn/Cu interface, which ...
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... an applied stress of 22.10 MPa (i.e., F = 4 N) is used in the simulation to evaluate the geometry effect on the crack driving force in the IMC layer. Fig. 14 shows the distribution of von Mises stress in the BGA solder joint. The highest stress appears at the crack tip of the IMC layer, but this does not mean that failure will occur. Herein, the SIFs and strain energy release rate are used to characterize the crack growth in the middle of the IMC layer. The mode I and II SIFs are given by ...
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... l is shear modulus; Dm and Dx are the relative displacements of the selected nodes of one crack-face relative to the other, and c is the original distance between the nodes selected to calculate the relative displacements and the crack tip, and c = 1.2 lm (see Fig. 3(c)). Since K III in the symmetry model must be zero, it is not considered here. Fig. 15 presents the FE results of SIFs and strain energy release rates at the crack tip in the IMC layer with different standoff heights. Clearly, K I increases sharply and K II gradually with increas- ing h as shown in Fig. 15(a). This can be explained as follows. With increasing h, the stress along the SAC305/IMC interface increases ...
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... and the crack tip, and c = 1.2 lm (see Fig. 3(c)). Since K III in the symmetry model must be zero, it is not considered here. Fig. 15 presents the FE results of SIFs and strain energy release rates at the crack tip in the IMC layer with different standoff heights. Clearly, K I increases sharply and K II gradually with increas- ing h as shown in Fig. 15(a). This can be explained as follows. With increasing h, the stress along the SAC305/IMC interface increases significantly due to stress concentration as indicated by the result and analysis in Section 3.2.2. During shear loading, the von Mises stress distributes more uniformly in the solder matrix of the BGA joint with h = 100 lm, being ...
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... increases significantly due to stress concentration as indicated by the result and analysis in Section 3.2.2. During shear loading, the von Mises stress distributes more uniformly in the solder matrix of the BGA joint with h = 100 lm, being more prone to concentrate along the SAC305/Cu 6 Sn 5 interface with increasing standoff height (see Fig. 9(a1)-(c1)). This means that the stress level around the crack, which is in the IMC layer and very close to the stress concentration zone, increases with increasing h. Thus, the SIFs at the crack tip also increase with ...
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... it is also clear that K I is obviously larger than K II under shear loading, as shown in Fig. 15(a). Thus, the opening mode (i.e., mode I) fracture occurs in the IMC layer. In mode I fracture, the strain energy release rate, G I , is given ...
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... v and E are Poisson ratio and elastic modulus of the Cu 6 Sn 5 layer, respectively, as given in Table 2. Under a shear force of 4 N, G I increases dramatically from 12.9 to 64.4 J/m 2 with increasing h from 100 to 500 lm, see Fig. 15(b). Therefore, increasing standoff height leads to increasing crack driving force and raises the risk of brittle fracture in the IMC layer. ...
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In this study, the shear performance and fracture behavior of microscale ball grid array (BGA) structure Cu/Sn–3.0Ag–0.5Cu/Cu joints with same solder volume and different heights at increasing current density were systematically investigated by experimental characterization, theoretical analysis, and finite element simulation. The results showed th...
Citations
... In that seek, many studies have analyzed the effect of the geometry of solder joints on their reliability as the work by (Ghenam et al., 2023) provided the optimal design of BGA solder joints using a Deterministic Design Optimization (DDO). Qin et al. (Qin et al., 2015) have investigated the geometry effect on mechanical performance and fracture behavior of micro-BGA structure solder joints using experimental and numerical procedures. Furthermore, Lau et al. (Lau et al., 2014) have evaluated the effect of solder joint geometry of ball grid array assembly with flexible and rigid PCBs on their reliability. ...
Metaheuristic optimization algorithms are powerful for solving complex optimization problems, almost when we lack information about the nature of their objective function. Meanwhile, the Finite Element Method (FEM) is a very powerful method for predicting and simulating the behavior of systems subjected to various stresses, whether electrical, thermal, mechanical, vibratory or magnetic.
In the current study, we have proposed an optimization methodology that couples a metaheuristic algorithm - the Search and Rescue Algorithm (SAR) - with the finite element method. We then investigated the proposed methodology for optimizing the reliability of solder balls with respect to their geometry in a Ball Grid Array (BGA) assembly subjected to thermal cycling load. First, we performed a sensitivity analysis to determine the parameters influencing solder ball reliability, then we optimized the plastic deformation of solder balls, hence increasing their reliability as a function of their geometry through the proposed methodology, which results in improving the reliability of the entire electronic component.
... As a result, the interfacial strain concentration is more serious when the deformation temperature is higher, which further accelerate the interfacial damage. The geometry and dimension of the microelectronic devices are also important external factors affecting the thermal fatigue resistance, because that will significantly affect the thermal strain and the stress concentration [39][40][41], and in turn the thermal fatigue damage rate. Besides, the microdefects formed in the solder joints usually become the crack initiation locations, and these defects are inevitable, thus these defects will decrease the resistance of the solder joint to thermal fatigue damage. ...
To intuitively reveal the influences of original solder grain orientation on thermal fatigue damage mechanisms of the SnAgCu/Cu solder joints at relatively high temperature, in this study the solder joints were prepared, and their thermal fatigue damage and microstructure evolution processes were in-situ characterized. It was found that most of the solder joints are single crystal, and the others have 2 or 3 solder grains. Under the thermal cycling of 20 °C ~ 140 °C, the interfacial strain concentration is more serious than that cycled at relatively low temperature, and the damage accumulation rate is higher. The original solder grain orientation determines the activation of slip systems and the plastic deformation degree, especially at the interfacial strain concentration zone. Due to softening of the solder and the high recovery rate, deformation of the solder not close to the joint interface is not very serious. The slip bands are not straight, and the activated slip systems are the {110}<001 > and {100}<001 > systems, but different slip systems can be activated at different zones within one solder grain. For the solder joints with 2 or 3 solder grains, deformation of the grain with higher Schmidt factor is restricted by the other grains, and the deformation mismatch resulting in grain boundary (GB) sliding. The high temperature recovery and relative torsion between different parts of the solder grains form new low-angle GBs. For a group of solder joints, the joint most susceptible to deformation determines the life of the device.
... Kim et al. [9] conducted the machine learning analysis to investigate the effect of the design pattern of the package substrate on the thermal properties that can effect deformation. Qin et al. [10] investigated the geometrical effects of individual solder joint models under the shear loading. Parametric modeling and lab-scale experiments on rectangular single solders were conducted by Shen et al. [11] and Chawla et al. [12], respectively. ...
Solder joints of ball grid arrays (BGA) have been widely used to connect electronic components to printed circuit boards (PCBs) and are often subjected to mechanical stress. Several studies have been conducted on the mechanical reliability of solder joints. While these studies have been useful in the industry, detailed studies on how the inelastic deformation path of the solder ball joints evolves under specific loading conditions have not been sufficiently reported. This study aims to understand how the inelastic deformation path evolves when a solder joint is subjected to a constant external force by utilizing the theory of mechanics. It has also been found that the mechanical failure is strongly influenced by the evolution history of the deformation modes in materials. For this study, an elastoplastic constitutive model and a ductile fracture criterion were implemented into the vectorized user-defined material (VUMAT) subroutine of the ABAQUS program for finite element (FE) analysis. With the model, the evolution of the inelastic deformation path of a single solder ball under different loading conditions was numerically analyzed. Three loadings (shear, compression, and bending) were chosen as the basic loading conditions. In addition, combinations of the basic loadings resulted in three dual loadings and one complex loading. The simulation results showed that the shear and bending caused the fracture for both single and dual loadings, but when combined with compression, the fracture was suppressed. The results indicate that fracture is not solely determined by the magnitude of equivalent plastic strain but also by the evolution of inelastic deformation mode. This research offers an improved understanding of the significance of the inelastic deformation path and fracture.
... Esta consideração é importante, pois ressalta a importância da presença de IMCs, que dificultam a condutividade elétrica nas interfaces dos contatos elétricos de cobre, onde tendem a ser mais numerosos. Desta forma, os IMCs são um fator relevante para a confiabilidade das uniões entre componentes eletrônicos e precisam ser avaliados em estudos mais amplos, como abordado por QIN et al. (2015); Tan et al. (2020) e Ren e Huang (2021). ...
Objetivo: Analisar as características de confiabilidade no uso de ligas isentas de chumbo empregadas na união elétrica, por soldagem branda, de circuitos eletrônicos. Métodos: Trata-se de uma revisão narrativa, realizada em 2023, focado na simulação mecânica do desempenho destas ligas em uniões de componentes eletrônicos do tipo Ball Grid Array (BGA), realizada por soldagem branda, incluindo estudos dos últimos cinco anos, de modo a descrever as particularidades dos fenômenos mecânico-metalúrgicos presentes nestas ligas especialmente sobre fadiga térmica, principal fenômeno degradativo associado às suas falhas. Resultados: Os resultados apontam que juntas SAC possuem diferentes graus de efetividade, em função da distribuição e posição das esferas (balls). Além disso, certas condições vinculadas à proximidade ao ponto eutético das ligas e a formação de compostos intermetálicos mostraram-se relevantes. Conclusões: a forma de análise abordada pode ser vantajosa para avaliar diferentes geometrias (arquiteturas) de juntas BGA, mas que precisa de complementações posteriores para abranger os efeitos dos mecanismos de alteração microestrutural das ligas estudadas.
... Decreasing standoff height increases the stiffness of BGA joints under shear loading due to decreasing coefficient of stress state in the solder matrix and torque caused by an induced moment of force. 36 It was also stated that a decrease in standoff height decreases the concentration of stress and plastic strain energy along the interface of solder and pad in BGA assembly, and a fracture location change from the solder matrix's middle to near the SAC305/ IMC interface was observed. Another related study advised on the effect of bump (component) height on plastics strain range and related it to fatigue life and reliability of Pb-free solder joints in electronic products. ...
Solder interconnection in electronic packaging is the weakest link and thus drives electronic modules and systems reliability. Improving the integrity of interconnection in safety-critical applications is vital in enhancing application reliability. This investigation qualifies the random vibration response of five essential solder compositions in ball grid array (BGA) solder joints used in safety-critical applications. The solder compositions are eutectic Sn63Pb37 and SnAgCu (SAC) 305, 387, 396, and 405. Computer-aided engineering (CAE) employing ANSYS FEA and SolidWorks software is implemented in this investigation. The solder Sn63Pb37 deformed least at 0.43 µm, followed by SAC396 at 0.58 µm, while SAC405 deformed highest at 0.88 µm. Further analysis demonstrates that possession of higher elastic modulus and mass density culminates in lower solder joint deformation. Stress is concentrated at the periphery of the solder joints in contact with the printed circuit board (PCB). The SAC396 solder accumulates the lowest stress of 14.1 MPa, followed by SAC405 at 17.9 MPa, while eutectic Sn63Pb37 accrues the highest at 34.6 MPa. Similarly, strain concentration is found at the interface between the solder joint and copper pad on PCB. SAC405 acquires the lowest elastic strain magnitude of 0.0011 mm/mm, while SAC305 records the highest strain of 0.002 mm/mm. These results demonstrate that SAC405 solder has maximum and SAC387 solder has minimum fatigue lives.
... Shear strength of Cu/SAC305/Cu solder joints at room temperature varies considerably under different experimental conditions, with most in the range of 30 * 60 MPa [45][46][47]. Isothermal aging and cyclic thermal aging tend to reduce shear strength of solder joints [21]. A Cu-ball solder joint always has a higher shear strength than a SAC joint [20]. ...
The thermal reliability, which results from CTE (coefficient of thermal expansion) mismatch among packaging materials, is essential to BGA (ball grid array) packaging electronic components. For reducing the CTE mismatch, tungsten ball BGA packaging was proposed in the present study. Core–shell-structured W@Cu balls were fabricated by copper electroplating on surfaces of tungsten balls. Single-ball joint specimens were made by reflow soldering a sandwich-structured Cu/W@Cu/Cu using Sn–Ag–Cu (SAC) solder paste. Two kinds of thermal aging treatments, namely isothermal aging and cyclic thermal aging, were conducted. The microstructure and shear strength of the joints were investigated. The results show that the average shear strength of the as-soldered single-ball joint samples is 57.9 MPa. It drops to 36.8 MPa and 33.4 MPa after isothermal aged at 170 °C for 250 h and cyclic thermal aged for 500 cycles, respectively. Cu6Sn5 IMC layer forms at boundaries of solder/Cu and grows with either isothermal aging time or cyclic thermal aging time. The roughness of the IMC increases with cyclic thermal aging time, but it changes little during isothermal aging process. The mechanism of microstructure and property evolution of single-ball solder joints under thermal aging have been briefly discussed.
... IMCs can give rise to a huge impact on the structural strength and material properties of solder interconnects, which powerfully correlate with the thermal-mechanical behavior of microelectronic packages. For instance, Qin et al. [16] reported that the growth in the IMCs' thickness above a threshold point would elevate the risk of interconnect damage under loads. Cheng et al. [17] also found that the drop impact interconnect fatigue life of three-dimensional (3D) chip-on-chip packaging would reduce with an increasing IMC thickness. ...
The intermetallic compounds (IMCs) at the interface between the solder joint and metal bond pad/under bump metallization (UBM) exert a significant impact on the thermal–mechanical behavior of microelectronic packages because of their unique physical properties. In this study, a theoretical investigation of the physical properties, namely structural, mechanical, and thermodynamic properties, of the Ag9In4 IMC was conducted using ab initio density functional theory (DFT) calculations. The calculated equilibrium lattice constants were in good agreement with the literature experimental data. Furthermore, with the calculated elastic constants, we can derive the ductility and brittleness nature, elastic anisotropy, and direction-dependent elastic properties of Ag9In4 through several elastic indices, three-dimensional surface representation, and two-dimensional projections of elastic properties. The calculations inferred that the cubic Ag9In4 IMC confers structural and mechanical stability, ductility, relative low stiffness and hardness, and elastic anisotropy. Finally, the thermodynamic properties, i.e., Debye temperature, heat capacity, and minimum thermal conductivity, were also investigated. Evidently, the low-temperature heat capacity conforms to the Debye heat capacity theory and the high-temperature one complies with the classical Dulong–Petit law.
... Previous studies have found that the joint size has a significant impact on solder joint reliability, including the mechanical reliability, such as tensile [11], shear [12], creep [13], and fatigue [14] performances. While, both the solder volume and joint height change simultaneously in some studies [15], leading to the uncertainty of which dimension factor dominating the variation of mechanical performance. Besides, after electronics production, the serving circumstances affect the solder joint reliability too [16]. ...
... One of the primary serving circumstances is electro-thermo-mechanical (ETM) coupled loads [17]. A large number of studies have been conducted on the reliability of solder joints under single load [15] or two loads [12]. In addition, the microstructure of solder joints varies with joint size after both electromigration and thermomigration [18][19][20], which should influence the subsequent mechanical performances of the solder joint too. ...
... Similar phenomenon was also reported in the line-type solder joint, where the theory of mechanical constraint was applied to explain the relationship between the tensile strength and joint height [34], which was also used in this paper. The mechanical constraint can be characterized by the average stress triaxiality of solder joint, R avc [15]: J Mater Sci: Mater Electron ...
In this study, the shear performance and fracture behavior of microscale ball grid array (BGA) structure Cu/Sn–3.0Ag–0.5Cu/Cu joints with same solder volume and different heights at increasing current density were systematically investigated by experimental characterization, theoretical analysis, and finite element simulation. The results showed that the shear strength of the solder joint decreased with increasing current density, while it increased with decreasing joint height. These changes were mainly due to Joule heating, the non-thermal effect of current stressing, and mechanical constraint in the solder joint. As current density increased, both Joule heating and the non-thermal effect of current stressing aggravated solder joint shear strength more and more severely. At the same current density, Joule heating’s deterioration on the shear strength was less serious in the smaller height joint, and the non-thermal effect was insensitive to the change in joint height. The higher shear strength of the smaller height joint was due to the larger mechanical constraint in the solder matrix induced by the substrate. Moreover, as current density increased, the fracture position changed from the solder matrix to the solder/IMC layer interface. The fracture mode shifted from ductile one to ductile–brittle-mixed one, and the critical current density corresponding to the fracture mode transition increased with decreasing joint height. The above findings indicate that the BGA structure solder joint with a smaller joint height is more reliable.
... Area array 30 devices, such as ball grid array (BGA) components, have 31 shown to be a viable solution for the needs of the industry. 32 BGA components, as one of the most essential component 33 packaging types, are widely utilized in many electronic appli-34 cations due to their high packaging density and reliability 35 [1]. Due to the high density printed circuit board assem-36 bly (PCBA) design, the BGA package development technol-37 ogy is heading toward finer pitch, smaller die, and thinner 38 packages [2]. ...
... 49 Crack initiation, crack propagation, damage accumulation, and 50 failures are all symptoms of fatigue failure of solder junctions 51 associated with the above factors due to the cyclic loadings [4]. 52 BGA solder joints are primarily prone to cyclic shear 53 stress in service due to the coefficient of thermal expansion 54 (CTE) mismatch between the chips, solder junctions, and 55 substrates [1]. 56 During the product development, accelerated reliability 57 testing via thermal cycling test (TCT) is often used for 58 analyzing and extrapolating the findings of these accelerated 59 reliability tests to real-world electronic assembly applica-60 tions. ...
... This is to ensure that the design and manufacturing 61 or assembly procedures are complying with the product's 62 desired performance goals [5]. Numerous research has been 63 carried out to investigate and simulate the solder joint crack 64 propagation behavior on BGA components when exposed 65 to thermal cycle loadings and most of them focus on the 66 individual solder joint [1], [ In this context, we analyzed the crack propagation orien-73 tation behavior on the BGA component solder array when test conditions profile was in the range of 0 • C-100 • C with 119 10 min for each hot and cold soak duration by a 10 • C per 120 minute ramp rate [9]. In the TCT chamber, all the test vehicle 121 samples were vertically mounted in individual slot fixtures 122 to provide suitable spacing between them together with a 123 thermocouple cable attached. ...
An accelerated reliability testing via thermal cycling test (TCT) was used to test ball grid array (BGA) components’ reliability. Five variables were observed; control sample J and samples K, L, M, and N were BGA component samples that have been exposed to TCT between 500 and 1250 cycles with the TCT profile in the range of 0 °C–100 °C. The crack orientation of the individual solder joint was analyzed along with the propagation path pattern on the solder array of the BGA component pad by analyzing the dye and pull test results that were then mapped and analyzed using the cardinal and ordinal directions approach. This is to determine the crack propagation path direction in the solder array and track the potential of warpage on the BGA package as the TCT cycles progressed. A cross section was performed on sample M with the 3-D X-ray and scanning electron microscopy (SEM) analysis to observe the solder joints’ fracture lines and surface topographies. The results showed that individual solder joint crack orientation is correlated to the crack propagation location on the BGA package. The solder joint from northwest (NW), northeast (NE), southeast (SE), and southwest (SW) of the BGA package is prone to solder crack compared to the solder joint array in the middle. A solder grain structure coarsening occurred at the crack propagation due to the high cyclic strain from the TCT.
... The interconnection joints are used in electronic packaging to provide electrical, thermal, and mechanical connections between components and chips in electronic devices [12]. There are different types of interconnection: inclusive of high-Pb solder bumps joined to a ceramic substrate, high-Pb bumps on-chip joined to eutectic PbSn on a laminate substrate, eutectic PbSn bumps, Pb-free bumps, Cu pillar bumps, and Au stud bumps [13]. ...
... Therefore, the discretization process takes place to convert the PDEs and corresponding boundary and initial conditions into discrete algebraic equations through the finite difference method (FDM) [95], finite element method (FEM) [41,48,81,86,91,[96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112], finite volume method (FVM) [96,97,[113][114][115][116], and lattice Boltzmann method [117]. The comparison between these discretization methods is briefed in Table 5 [12,117,118]. The FVM-based CFD is preferable because the mathematical formulation of FVM is based on physics laws and conservation principles. ...
This paper reviewed the state-of-art copper pillar technology in flip-chip packaging, driven by the semiconductor industry’s demands for thinner and faster data transmission. This technology with area array feature is a surface mount technology process used to form interconnection bonding between ball grid array chip and printed circuit board (PCB) by the reflow soldering process. The conversion of the flip-chip interconnection bump from the solder ball to the Cu pillar bump with the solder cap and the joint performance within the reflow oven are presented in this review. The simulation tools have recently facilitated the Cu pillar bump research during the PCB assembly process. Thus, this review focuses on the simulation modeling of the PCB assembly within a reflow oven using different numerical approaches. The thermal and air flow aspects of the reflow process are reviewed. The temperature distribution and the thermal stress condition of the PCB assembly within the reflow oven are predicted to understand better the fluid–structure interaction in the reflow oven. The considerations of air flow and thermal effects enhanced the study of fluid flow on the PCB assembly. Moreover, the Cu pillar technology challenges are also highlighted in this review. This review paper is expected to provide necessary information and direction to future researchers and industrial engineers when designing a brand-new surface-mounted component.
