Soldering & Surface Mount TechnologyTable of Contents for Soldering & Surface Mount Technology. List of articles from the current issue, including Just Accepted (EarlyCite)https://www.emerald.com/insight/publication/issn/0954-0911/vol/36/iss/2?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestSoldering & Surface Mount TechnologyEmerald Publishing LimitedSoldering & Surface Mount TechnologySoldering & Surface Mount Technologyhttps://www.emerald.com/insight/proxy/containerImg?link=/resource/publication/journal/aca55900acbe06e96eaac35800126c7e/urn:emeraldgroup.com:asset:id:binary:ssmt.cover.jpghttps://www.emerald.com/insight/publication/issn/0954-0911/vol/36/iss/2?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestLow-cycle fatigue life assessment of SAC solder alloy through a FEM-data driven machine learning approachhttps://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0045/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis paper aims to present the novel stacked machine learning approach (SMLA) to estimate low-cycle fatigue (LCF) life of SAC305 solder across structural parts. Using the finite element simulation (FEM) and continuous damage mechanics (CDM) model, a fatigue life database is built. The stacked machine learning (ML) model's iterative optimization during training enables precise fatigue predictions (2.41% root mean square error [RMSE], R2 = 0.975) for diverse structural components. Outliers are found in regression analysis, indicating potential overestimation for thickness transition specimens with extended lifetimes and underestimation for open-hole specimens. Correlations between fatigue life, stress factors, nominal stress and temperature are unveiled, enriching comprehension of LCF, thus enhancing solder behavior predictions. This paper introduces stacked ML as a novel approach for estimating LCF life of SAC305 solder in various structural parts. It builds a fatigue life database using FEM and CDM model. The stacked ML model iteratively optimizes its structure, yielding accurate fatigue predictions (2.41% RMSE, R2 = 0.975). Outliers are observed: overestimation for thickness transition specimens and underestimation for open-hole ones. Correlations between fatigue life, stress factors, nominal stress and temperature enhance predictions, deepening understanding of solder behavior. The findings of this paper highlight the successful application of the SMLA in accurately estimating the LCF life of SAC305 solder across diverse structural components. The stacked ML model, trained iteratively, demonstrates its effectiveness by producing precise fatigue lifetime predictions with a RMSE of 2.41% and an “R2” value of 0.975. The study also identifies distinct outlier behaviors associated with different structural parts: overestimations for thickness transition specimens with extended fatigue lifetimes and underestimations for open-hole specimens. The research further establishes correlations between fatigue life, stress concentration factors, nominal stress and temperature, enriching the understanding of solder behavior prediction. The authors confirm the originality of this paper.Low-cycle fatigue life assessment of SAC solder alloy through a FEM-data driven machine learning approach
Vicente-Segundo Ruiz-Jacinto, Karina-Silvana Gutiérrez-Valverde, Abrahan-Pablo Aslla-Quispe, José-Manuel Burga-Falla, Aldo Alarcón-Sucasaca, Yersi-Luis Huamán-Romaní
Soldering & Surface Mount Technology, Vol. 36, No. 2, pp.69-79

This paper aims to present the novel stacked machine learning approach (SMLA) to estimate low-cycle fatigue (LCF) life of SAC305 solder across structural parts. Using the finite element simulation (FEM) and continuous damage mechanics (CDM) model, a fatigue life database is built. The stacked machine learning (ML) model's iterative optimization during training enables precise fatigue predictions (2.41% root mean square error [RMSE], R2 = 0.975) for diverse structural components. Outliers are found in regression analysis, indicating potential overestimation for thickness transition specimens with extended lifetimes and underestimation for open-hole specimens. Correlations between fatigue life, stress factors, nominal stress and temperature are unveiled, enriching comprehension of LCF, thus enhancing solder behavior predictions.

This paper introduces stacked ML as a novel approach for estimating LCF life of SAC305 solder in various structural parts. It builds a fatigue life database using FEM and CDM model. The stacked ML model iteratively optimizes its structure, yielding accurate fatigue predictions (2.41% RMSE, R2 = 0.975). Outliers are observed: overestimation for thickness transition specimens and underestimation for open-hole ones. Correlations between fatigue life, stress factors, nominal stress and temperature enhance predictions, deepening understanding of solder behavior.

The findings of this paper highlight the successful application of the SMLA in accurately estimating the LCF life of SAC305 solder across diverse structural components. The stacked ML model, trained iteratively, demonstrates its effectiveness by producing precise fatigue lifetime predictions with a RMSE of 2.41% and an “R2” value of 0.975. The study also identifies distinct outlier behaviors associated with different structural parts: overestimations for thickness transition specimens with extended fatigue lifetimes and underestimations for open-hole specimens. The research further establishes correlations between fatigue life, stress concentration factors, nominal stress and temperature, enriching the understanding of solder behavior prediction.

The authors confirm the originality of this paper.

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Low-cycle fatigue life assessment of SAC solder alloy through a FEM-data driven machine learning approach10.1108/SSMT-08-2023-0045Soldering & Surface Mount Technology2023-09-28© 2023 Emerald Publishing LimitedVicente-Segundo Ruiz-JacintoKarina-Silvana Gutiérrez-ValverdeAbrahan-Pablo Aslla-QuispeJosé-Manuel Burga-FallaAldo Alarcón-SucasacaYersi-Luis Huamán-RomaníSoldering & Surface Mount Technology3622023-09-2810.1108/SSMT-08-2023-0045https://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0045/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2023 Emerald Publishing Limited
Temperature and current density prediction in solder joints using artificial neural network methodhttps://www.emerald.com/insight/content/doi/10.1108/SSMT-07-2023-0040/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestDue to the miniaturization of electronic devices, the increased current density through solder joints leads to the occurrence of electromigration failure, thereby reducing the reliability of electronic devices. The purpose of this study is to propose a finite element-artificial neural network method for the prediction of temperature and current density of solder joints, and thus provide reference information for the reliability evaluation of solder joints. The temperature distribution and current density distribution of the interconnect structure of electronic devices were investigated through finite element simulations. During the experimental process, the actual temperature of the solder joints was measured and was used to optimize the finite element model. A large amount of simulation data was obtained to analyze the neural network by varying the height of solder joints, the diameter of solder pads and the magnitude of current loads. The constructed neural network was trained, tested and optimized using this data. Based on the finite element simulation results, the current is more concentrated in the corners of the solder joints, generating a significant amount of Joule heating, which leads to localized temperature rise. The constructed neural network is trained, tested and optimized using the simulation results. The ANN 1, used for predicting solder joint temperature, achieves a prediction accuracy of 96.9%, while the ANN 2, used for predicting solder joint current density, achieves a prediction accuracy of 93.4%. The proposed method can effectively improve the estimation efficiency of temperature and current density in the packaging structure. This method prevails in the field of packaging, and other factors that affect the thermal, mechanical and electrical properties of the packaging structure can be introduced into the model.Temperature and current density prediction in solder joints using artificial neural network method
Yang Liu, Xin Xu, Shiqing Lv, Xuewei Zhao, Yuxiong Xue, Shuye Zhang, Xingji Li, Chaoyang Xing
Soldering & Surface Mount Technology, Vol. 36, No. 2, pp.80-92

Due to the miniaturization of electronic devices, the increased current density through solder joints leads to the occurrence of electromigration failure, thereby reducing the reliability of electronic devices. The purpose of this study is to propose a finite element-artificial neural network method for the prediction of temperature and current density of solder joints, and thus provide reference information for the reliability evaluation of solder joints.

The temperature distribution and current density distribution of the interconnect structure of electronic devices were investigated through finite element simulations. During the experimental process, the actual temperature of the solder joints was measured and was used to optimize the finite element model. A large amount of simulation data was obtained to analyze the neural network by varying the height of solder joints, the diameter of solder pads and the magnitude of current loads. The constructed neural network was trained, tested and optimized using this data.

Based on the finite element simulation results, the current is more concentrated in the corners of the solder joints, generating a significant amount of Joule heating, which leads to localized temperature rise. The constructed neural network is trained, tested and optimized using the simulation results. The ANN 1, used for predicting solder joint temperature, achieves a prediction accuracy of 96.9%, while the ANN 2, used for predicting solder joint current density, achieves a prediction accuracy of 93.4%.

The proposed method can effectively improve the estimation efficiency of temperature and current density in the packaging structure. This method prevails in the field of packaging, and other factors that affect the thermal, mechanical and electrical properties of the packaging structure can be introduced into the model.

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Temperature and current density prediction in solder joints using artificial neural network method10.1108/SSMT-07-2023-0040Soldering & Surface Mount Technology2023-12-04© 2023 Emerald Publishing LimitedYang LiuXin XuShiqing LvXuewei ZhaoYuxiong XueShuye ZhangXingji LiChaoyang XingSoldering & Surface Mount Technology3622023-12-0410.1108/SSMT-07-2023-0040https://www.emerald.com/insight/content/doi/10.1108/SSMT-07-2023-0040/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2023 Emerald Publishing Limited
A 3D coaxial transition with continuous ground wall fabricated by a 12-inch wafer-level packaging method for radio frequency applicationshttps://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0051/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis paper aims to realize the vertical interconnection in 3D radio frequency (RF) circuit by coaxial transitions with broad working bandwidth and small signal loss. An advanced packaging method, 12-inch wafer-level through-mold-via (TMV) additive manufacturing, is used to fabricate a 3D resin-based coaxial transition with a continuous ground wall (named resin-coaxial transition). Designation and simulation are implemented to ensure the application universality and fabrication feasibility. The outer radius R of coaxial transition is optimized by designing and fabricating three samples. The fabricated coaxial transition possesses an inner radius of 40 µm and a length of 200 µm. The optimized sample with an outer radius R of 155 µm exhibits S11 < –10 dB and S21 > –1.3 dB at 10–110 GHz and the smallest insertion loss (S21 = 0.83 dB at 77 GHz) among the samples. Moreover, the S21 of the samples increases at 58.4–90.1 GHz, indicating a broad and suitable working bandwidth. The wafer-level TMV additive manufacturing method is applied to fabricate coaxial transitions for the first time. The fabricated resin-coaxial transitions show good performance up to the W-band. It may provide new strategies for novel designing and fabricating methods of RF transitions.A 3D coaxial transition with continuous ground wall fabricated by a 12-inch wafer-level packaging method for radio frequency applications
Xinran Zhao, Yingying Pang, Gang Wang, Chenhui Xia, Yuan Yuan, Chengqian Wang
Soldering & Surface Mount Technology, Vol. 36, No. 2, pp.93-100

This paper aims to realize the vertical interconnection in 3D radio frequency (RF) circuit by coaxial transitions with broad working bandwidth and small signal loss.

An advanced packaging method, 12-inch wafer-level through-mold-via (TMV) additive manufacturing, is used to fabricate a 3D resin-based coaxial transition with a continuous ground wall (named resin-coaxial transition). Designation and simulation are implemented to ensure the application universality and fabrication feasibility. The outer radius R of coaxial transition is optimized by designing and fabricating three samples.

The fabricated coaxial transition possesses an inner radius of 40 µm and a length of 200 µm. The optimized sample with an outer radius R of 155 µm exhibits S11 < –10 dB and S21 > –1.3 dB at 10–110 GHz and the smallest insertion loss (S21 = 0.83 dB at 77 GHz) among the samples. Moreover, the S21 of the samples increases at 58.4–90.1 GHz, indicating a broad and suitable working bandwidth.

The wafer-level TMV additive manufacturing method is applied to fabricate coaxial transitions for the first time. The fabricated resin-coaxial transitions show good performance up to the W-band. It may provide new strategies for novel designing and fabricating methods of RF transitions.

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A 3D coaxial transition with continuous ground wall fabricated by a 12-inch wafer-level packaging method for radio frequency applications10.1108/SSMT-08-2023-0051Soldering & Surface Mount Technology2023-12-21© 2023 Emerald Publishing LimitedXinran ZhaoYingying PangGang WangChenhui XiaYuan YuanChengqian WangSoldering & Surface Mount Technology3622023-12-2110.1108/SSMT-08-2023-0051https://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0051/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2023 Emerald Publishing Limited
Numerical investigation of thermal fatigue crack growth behavior in SAC305 BGA solder jointshttps://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0049/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis study aims to investigate the reliability issues of microvoid cracks in solder joint packages exposed to thermal cycling fatigue. The specimens are subjected to JEDEC preconditioning level 1 (85 °C/85%RH/168 h) with five times reflow at 270°C. This is followed by thermal cycling from 0°C to 100°C, per IPC-7351B standards. The specimens' cross-sections are inspected for crack growth and propagation under backscattered scanning electronic microscopy. The decoupled thermomechanical simulation technique is applied to investigate the thermal fatigue behavior. The impacts of crack length on the stress and fatigue behavior of the package are investigated. Cracks are initiated from the ball grid array corner of the solder joint, propagating through the transverse section of the solder ball. The crack growth increases continuously up to 0.25-mm crack length, then slows down afterward. The J-integral and stress intensity factor (SIF) values at the crack tip decrease with increased crack length. Before 0.15-mm crack length, J-integral and SIF reduce slightly with crack length and are comparatively higher, resulting in a rapid increase in crack mouth opening displacement (CMOD). Beyond 0.25-mm crack length, the values significantly decline, that there is not much possibility of crack growth, resulting in a negligible change in CMOD value. This explains the crack growth arrest obtained after 0.25-mm crack length. This work's contribution is expected to reduce the additional manufacturing cost and lead time incurred in investigating reliability issues in solder joints. The work investigates crack propagation mechanisms of microvoid cracks in solder joints exposed to moisture and thermal fatigue, which is still limited in the literature. The parametric variation of the crack length on stress and fatigue characteristics of solder joints, which has never been conducted, is also studied.Numerical investigation of thermal fatigue crack growth behavior in SAC305 BGA solder joints
Rilwan Kayode Apalowo, Mohamad Aizat Abas, Muhamed Abdul Fatah Muhamed Mukhtar, Fakhrozi Che Ani, Mohamad Riduwan Ramli
Soldering & Surface Mount Technology, Vol. 36, No. 2, pp.101-110

This study aims to investigate the reliability issues of microvoid cracks in solder joint packages exposed to thermal cycling fatigue.

The specimens are subjected to JEDEC preconditioning level 1 (85 °C/85%RH/168 h) with five times reflow at 270°C. This is followed by thermal cycling from 0°C to 100°C, per IPC-7351B standards. The specimens' cross-sections are inspected for crack growth and propagation under backscattered scanning electronic microscopy. The decoupled thermomechanical simulation technique is applied to investigate the thermal fatigue behavior. The impacts of crack length on the stress and fatigue behavior of the package are investigated.

Cracks are initiated from the ball grid array corner of the solder joint, propagating through the transverse section of the solder ball. The crack growth increases continuously up to 0.25-mm crack length, then slows down afterward. The J-integral and stress intensity factor (SIF) values at the crack tip decrease with increased crack length. Before 0.15-mm crack length, J-integral and SIF reduce slightly with crack length and are comparatively higher, resulting in a rapid increase in crack mouth opening displacement (CMOD). Beyond 0.25-mm crack length, the values significantly decline, that there is not much possibility of crack growth, resulting in a negligible change in CMOD value. This explains the crack growth arrest obtained after 0.25-mm crack length.

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

The work investigates crack propagation mechanisms of microvoid cracks in solder joints exposed to moisture and thermal fatigue, which is still limited in the literature. The parametric variation of the crack length on stress and fatigue characteristics of solder joints, which has never been conducted, is also studied.

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Numerical investigation of thermal fatigue crack growth behavior in SAC305 BGA solder joints10.1108/SSMT-08-2023-0049Soldering & Surface Mount Technology2024-01-01© 2023 Emerald Publishing LimitedRilwan Kayode ApalowoMohamad Aizat AbasMuhamed Abdul Fatah Muhamed MukhtarFakhrozi Che AniMohamad Riduwan RamliSoldering & Surface Mount Technology3622024-01-0110.1108/SSMT-08-2023-0049https://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0049/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2023 Emerald Publishing Limited
Structural, thermal and mechanical properties of rapidly solidified Bi-0.5Ag lead-free solder reinforced Tb rare-earth element for high performance applicationshttps://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0052/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThe purpose of the present work is to study the impacts of rapid cooling and Tb rare-earth additions on the structural, thermal and mechanical behavior of Bi–0.5Ag lead-free solder for high-temperature applications. Effect of rapid solidification processing on structural, thermal and mechanical properties of Bi-Ag lead-free solder reinforced Tb rare-earth element. The obtained results indicated that the microstructure consists of rhombohedral Bi-rich phase and Ag99.5Bi0.5 intermetallic compound (IMC). The addition of Tb could effectively reduce the onset and melting point. The elastic modulus of Tb-containing solders was enhanced to about 90% at 0.5 Tb. The higher elastic modulus may be attributed to solid solution strengthening effect, solubility extension, microstructure refinement and precipitation hardening of uniform distribution Ag99.5Bi0.5 IMC particles which can reasonably modify the microstructure, as well as inhibit the segregation and hinder the motion of dislocations. It is recommended that the lead-free Bi-0.5Ag-0.5Tb solder be a candidate instead of common solder alloy (Sn-37Pb) for high temperature and high performance applications.Structural, thermal and mechanical properties of rapidly solidified Bi-0.5Ag lead-free solder reinforced Tb rare-earth element for high performance applications
Rizk Mostafa Shalaby, Mohamed Saad
Soldering & Surface Mount Technology, Vol. 36, No. 2, pp.111-122

The purpose of the present work is to study the impacts of rapid cooling and Tb rare-earth additions on the structural, thermal and mechanical behavior of Bi–0.5Ag lead-free solder for high-temperature applications.

Effect of rapid solidification processing on structural, thermal and mechanical properties of Bi-Ag lead-free solder reinforced Tb rare-earth element.

The obtained results indicated that the microstructure consists of rhombohedral Bi-rich phase and Ag99.5Bi0.5 intermetallic compound (IMC). The addition of Tb could effectively reduce the onset and melting point. The elastic modulus of Tb-containing solders was enhanced to about 90% at 0.5 Tb. The higher elastic modulus may be attributed to solid solution strengthening effect, solubility extension, microstructure refinement and precipitation hardening of uniform distribution Ag99.5Bi0.5 IMC particles which can reasonably modify the microstructure, as well as inhibit the segregation and hinder the motion of dislocations.

It is recommended that the lead-free Bi-0.5Ag-0.5Tb solder be a candidate instead of common solder alloy (Sn-37Pb) for high temperature and high performance applications.

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Structural, thermal and mechanical properties of rapidly solidified Bi-0.5Ag lead-free solder reinforced Tb rare-earth element for high performance applications10.1108/SSMT-08-2023-0052Soldering & Surface Mount Technology2024-02-09© 2024 Emerald Publishing LimitedRizk Mostafa ShalabyMohamed SaadSoldering & Surface Mount Technology3622024-02-0910.1108/SSMT-08-2023-0052https://www.emerald.com/insight/content/doi/10.1108/SSMT-08-2023-0052/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2024 Emerald Publishing Limited
The research on the application of self-propagating interconnection technology in silicon optical transceiver module for aerospacehttps://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0056/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis paper aims to investigate the bonding of the photonic integrated circuit (PIC) chip with the heat sink using the AlNi self-propagating soldering method. Compared to industrial optical modules, optical modules for aerospace applications require better reliability and stability, which is hard to achieve via the dispensing adhesive process that is used for traditional industrial optical modules. In this paper, 25 µm SAC305 solder foils and the AlNi nanofoil heat source were used to bond the back of the PIC chip with the heat sink. The temperature field and temperature history were analyzed by the finite element analysis (FEA) method. The junction-to-case thermal resistance is 0.0353°C/W and reduced by 85% compared with the UV hybrid epoxy joint. The self-propagating reaction ends within 2.82 ms. The maximum temperature in the PIC operating area during the process is 368.5°C. The maximum heating and cooling rates of the solder were 1.39 × 107°C/s and −5.15 × 106°C/s, respectively. The microstructure of SAC305 under self-propagating reaction heating is more refined than the microstructure of SAC305 under reflow. The porosity of the heat sink-SAC305-PIC chip self-propagating joint is only 4.7%. Several metastable phases appear as AuSn3.4 and AgSn3. A new bonding technology was used to form the bonding between the PIC chip with the heat sink for the aerospace optical module. The reliability and thermal resistance of the joint are better than that of the UV hybrid epoxy joint.The research on the application of self-propagating interconnection technology in silicon optical transceiver module for aerospace
Fei Chu, Hongzhuan Chen, Zheng Zhou, Changlei Feng, Tao Zhang
Soldering & Surface Mount Technology, Vol. 36, No. 2, pp.123-131

This paper aims to investigate the bonding of the photonic integrated circuit (PIC) chip with the heat sink using the AlNi self-propagating soldering method.

Compared to industrial optical modules, optical modules for aerospace applications require better reliability and stability, which is hard to achieve via the dispensing adhesive process that is used for traditional industrial optical modules. In this paper, 25 µm SAC305 solder foils and the AlNi nanofoil heat source were used to bond the back of the PIC chip with the heat sink. The temperature field and temperature history were analyzed by the finite element analysis (FEA) method. The junction-to-case thermal resistance is 0.0353°C/W and reduced by 85% compared with the UV hybrid epoxy joint.

The self-propagating reaction ends within 2.82 ms. The maximum temperature in the PIC operating area during the process is 368.5°C. The maximum heating and cooling rates of the solder were 1.39 × 107°C/s and −5.15 × 106°C/s, respectively. The microstructure of SAC305 under self-propagating reaction heating is more refined than the microstructure of SAC305 under reflow. The porosity of the heat sink-SAC305-PIC chip self-propagating joint is only 4.7%. Several metastable phases appear as AuSn3.4 and AgSn3.

A new bonding technology was used to form the bonding between the PIC chip with the heat sink for the aerospace optical module. The reliability and thermal resistance of the joint are better than that of the UV hybrid epoxy joint.

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The research on the application of self-propagating interconnection technology in silicon optical transceiver module for aerospace10.1108/SSMT-10-2023-0056Soldering & Surface Mount Technology2023-12-15© 2023 Emerald Publishing LimitedFei ChuHongzhuan ChenZheng ZhouChanglei FengTao ZhangSoldering & Surface Mount Technology3622023-12-1510.1108/SSMT-10-2023-0056https://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0056/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2023 Emerald Publishing Limited
Anand constitutive modeling of multilayer Silver-Tin transient liquid phase foils using tensile and creep testinghttps://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0061/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis paper aims to present two Anand’s model parameter sets for the multilayer silver–tin (AgSn) transient liquid phase (TLP) foils. The AgSn TLP test samples are manufactured using pre-defined optimized TLP bonding process parameters. Consequently, tensile and creep tests are conducted at various loading temperatures to generate stress–strain and creep data to accurately determine the elastic properties and two sets of Anand model creep coefficients. The resultant tensile- and creep-based constitutive models are subsequently used in extensive finite element simulations to precisely survey the mechanical response of the AgSn TLP bonds in power electronics due to different thermal loads. The response of both models is thoroughly addressed in terms of stress–strain relationships, inelastic strain energy densities and equivalent plastic strains. The simulation results revealed that the testing conditions and parameters can significantly influence the values of the fitted Anand coefficients and consequently affect the resultant FEA-computed mechanical response of the TLP bonds. Therefore, this paper suggests that extreme care has to be taken when planning experiments for the estimation of creep parameters of the AgSn TLP joints. In literature, there is no constitutive modeling data on the AgSn TLP bonds.Anand constitutive modeling of multilayer Silver-Tin transient liquid phase foils using tensile and creep testing
Mohammad A Gharaibeh, Markus Feisst, Jürgen Wilde
Soldering & Surface Mount Technology, Vol. 36, No. 2, pp.132-143

This paper aims to present two Anand’s model parameter sets for the multilayer silver–tin (AgSn) transient liquid phase (TLP) foils.

The AgSn TLP test samples are manufactured using pre-defined optimized TLP bonding process parameters. Consequently, tensile and creep tests are conducted at various loading temperatures to generate stress–strain and creep data to accurately determine the elastic properties and two sets of Anand model creep coefficients. The resultant tensile- and creep-based constitutive models are subsequently used in extensive finite element simulations to precisely survey the mechanical response of the AgSn TLP bonds in power electronics due to different thermal loads.

The response of both models is thoroughly addressed in terms of stress–strain relationships, inelastic strain energy densities and equivalent plastic strains. The simulation results revealed that the testing conditions and parameters can significantly influence the values of the fitted Anand coefficients and consequently affect the resultant FEA-computed mechanical response of the TLP bonds. Therefore, this paper suggests that extreme care has to be taken when planning experiments for the estimation of creep parameters of the AgSn TLP joints.

In literature, there is no constitutive modeling data on the AgSn TLP bonds.

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Anand constitutive modeling of multilayer Silver-Tin transient liquid phase foils using tensile and creep testing10.1108/SSMT-10-2023-0061Soldering & Surface Mount Technology2024-01-15© 2024 Emerald Publishing LimitedMohammad A GharaibehMarkus FeisstJürgen WildeSoldering & Surface Mount Technology3622024-01-1510.1108/SSMT-10-2023-0061https://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0061/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2024 Emerald Publishing Limited
A temperature control method of hot-bar soldering based on extended Kalman filterhttps://www.emerald.com/insight/content/doi/10.1108/SSMT-02-2023-0006/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis study aims to introduce a novel technique for nonlinear sensor time constant estimation and sensor dynamic compensation in hot-bar soldering using an extended Kalman filter (EKF) to estimate the temperature of the thermocouple. Temperature optimal control is combined with a closed-loop proportional integral differential (PID) control method based on an EKF. Different control methods for measuring the temperature of the thermode in terms of temperature control, error and antidisturbance are studied. A soldering process in a semi-industrial environment is performed. The proposed control method was applied to the soldering of flexible printed circuits and circuit boards. An infrared camera was used to measure the top-surface temperature. The proposed method can not only estimate the soldering temperature but also eliminate the noise of the system. The performance of this methodology was exemplary, characterized by rapid convergence and negligible error margins. Compared with the conventional control, the temperature variability of the proposed control is significantly attenuated. An EKF was designed to estimate the temperature of the thermocouple during hot-bar soldering. Using the EKF and PID controller, the nonlinear properties of the system could be effectively overcome and the effects of disturbances and system noise could be decreased. The proposed method significantly enhanced the temperature control performance of hot-bar soldering, effectively suppressing overshoot and shortening the adjustment time, thereby achieving precise temperature control of the controlled object.A temperature control method of hot-bar soldering based on extended Kalman filter
Min Zeng, Jianxing Xie, Zhitao Li, Qincheng Wei, Hui Yang
Soldering & Surface Mount Technology, Vol. ahead-of-print, No. ahead-of-print, pp.-

This study aims to introduce a novel technique for nonlinear sensor time constant estimation and sensor dynamic compensation in hot-bar soldering using an extended Kalman filter (EKF) to estimate the temperature of the thermocouple.

Temperature optimal control is combined with a closed-loop proportional integral differential (PID) control method based on an EKF. Different control methods for measuring the temperature of the thermode in terms of temperature control, error and antidisturbance are studied. A soldering process in a semi-industrial environment is performed. The proposed control method was applied to the soldering of flexible printed circuits and circuit boards. An infrared camera was used to measure the top-surface temperature.

The proposed method can not only estimate the soldering temperature but also eliminate the noise of the system. The performance of this methodology was exemplary, characterized by rapid convergence and negligible error margins. Compared with the conventional control, the temperature variability of the proposed control is significantly attenuated.

An EKF was designed to estimate the temperature of the thermocouple during hot-bar soldering. Using the EKF and PID controller, the nonlinear properties of the system could be effectively overcome and the effects of disturbances and system noise could be decreased. The proposed method significantly enhanced the temperature control performance of hot-bar soldering, effectively suppressing overshoot and shortening the adjustment time, thereby achieving precise temperature control of the controlled object.

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A temperature control method of hot-bar soldering based on extended Kalman filter10.1108/SSMT-02-2023-0006Soldering & Surface Mount Technology2024-03-18© 2024 Emerald Publishing LimitedMin ZengJianxing XieZhitao LiQincheng WeiHui YangSoldering & Surface Mount Technologyahead-of-printahead-of-print2024-03-1810.1108/SSMT-02-2023-0006https://www.emerald.com/insight/content/doi/10.1108/SSMT-02-2023-0006/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2024 Emerald Publishing Limited
Influences of hygrothermal conditions and structure parameters on moisture diffusion behavior in a system‐in‐package module by moisture-thermal-mechanical-coupled finite element modelinghttps://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0059/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis paper aims to investigate the moisture diffusion behavior in a system-in-package module systematically by moisture-thermalmechanical-coupled finite element modeling with different structure parameters under increasingly harsh environment. A finite element model for a system-in-package module was built with moisture-thermal-mechanical-coupled effects to study the subsequences of hygrothermal conditions. It was found in this paper that the moisture diffusion path was mainly dominated by hygrothermal conditions, though structure parameters can affect the moisture distribution. At lower temperatures (30°C~85°C), the direction of moisture diffusion was from the periphery to the center of the module, which was commonly found in simulations and literatures. However, at relatively higher temperatures (125°C~220°C), the diffusion was from printed circuit board (PCB) to EMC due to the concentration gradient from PCB to EMC across the EMC/PCB interface. It was also found that there exists a critical thickness for EMC and PCB during the moisture diffusion. When the thickness of EMC or PCB increased to a certain value, the diffusion of moisture reached a stable state, and the concentration on the die surface in the packaging module hardly changed. A quantified correlation between the moisture diffusion coefficient and the critical thickness was then proposed for structure parameter optimization in the design of system-in-package module. The different moisture diffusion behaviors at low and high temperatures have seldom been reported before. This work can facilitate the understanding of moisture diffusion within a package and offer some methods about minimizing its effect by design optimization.Influences of hygrothermal conditions and structure parameters on moisture diffusion behavior in a system‐in‐package module by moisture-thermal-mechanical-coupled finite element modeling
Li Liu, Chunhua Zhang, Ping Hu, Sheng Liu, Zhiwen Chen
Soldering & Surface Mount Technology, Vol. ahead-of-print, No. ahead-of-print, pp.-

This paper aims to investigate the moisture diffusion behavior in a system-in-package module systematically by moisture-thermalmechanical-coupled finite element modeling with different structure parameters under increasingly harsh environment.

A finite element model for a system-in-package module was built with moisture-thermal-mechanical-coupled effects to study the subsequences of hygrothermal conditions.

It was found in this paper that the moisture diffusion path was mainly dominated by hygrothermal conditions, though structure parameters can affect the moisture distribution. At lower temperatures (30°C~85°C), the direction of moisture diffusion was from the periphery to the center of the module, which was commonly found in simulations and literatures. However, at relatively higher temperatures (125°C~220°C), the diffusion was from printed circuit board (PCB) to EMC due to the concentration gradient from PCB to EMC across the EMC/PCB interface. It was also found that there exists a critical thickness for EMC and PCB during the moisture diffusion. When the thickness of EMC or PCB increased to a certain value, the diffusion of moisture reached a stable state, and the concentration on the die surface in the packaging module hardly changed. A quantified correlation between the moisture diffusion coefficient and the critical thickness was then proposed for structure parameter optimization in the design of system-in-package module.

The different moisture diffusion behaviors at low and high temperatures have seldom been reported before. This work can facilitate the understanding of moisture diffusion within a package and offer some methods about minimizing its effect by design optimization.

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Influences of hygrothermal conditions and structure parameters on moisture diffusion behavior in a system‐in‐package module by moisture-thermal-mechanical-coupled finite element modeling10.1108/SSMT-10-2023-0059Soldering & Surface Mount Technology2024-03-18© 2024 Emerald Publishing LimitedLi LiuChunhua ZhangPing HuSheng LiuZhiwen ChenSoldering & Surface Mount Technologyahead-of-printahead-of-print2024-03-1810.1108/SSMT-10-2023-0059https://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0059/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2024 Emerald Publishing Limited
Influence of doping SiN nanoparticles on the properties and microstructure of Sn58Bi solder for connecting Cu substratehttps://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0060/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestThis study aims to explore the feasibility of adding Si3N4 nanoparticles to Sn58Bi and provides a theoretical basis for designing and applying new lead-free solder materials for the electronic packaging industry. In this paper, Sn58Bi-xSi3N4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 Wt.%) was prepared for bonding Cu substrate, and the changes in thermal properties, wettability, microstructure, interfacial intermetallic compound and mechanical properties of the composite solder were systematically studied. The experiment results demonstrate that including Si3N4 nanoparticles does not significantly impact the melting point of Sn58Bi solder, and the undercooling degree of solder only fluctuates slightly. The molten solder spreading area reached a maximum of 96.17 mm2, raised by 19.41% relative to those without Si3N4, and the wetting angle was the smallest at 0.6 Wt.% of Si3N4, with a minimum value of 8.35°. When the Si3N4 nanoparticles reach 0.6 Wt.%, the solder joint microstructure is significantly refined. Appropriately adding Si3N4 nanoparticles will slightly increase the solder alloy hardness. When the concentration of Si3N4 reaches 0.6 Wt.%, the joints shear strength reached 45.30 MPa, representing a 49.85% increase compared to those without additives. A thorough examination indicates that legitimately incorporating Si3N4 nanoparticles into Sn58Bi solder can enhance its synthetical performance, and 0.6 Wt.% is the best addition amount in our test setting. In this paper, Si3N4 nanoparticles were incorporated into Sn58Bi solder, and the effects of different contents of Si3N4 nanoparticles on Sn58Bi solder were investigated from various aspects.Influence of doping SiN nanoparticles on the properties and microstructure of Sn58Bi solder for connecting Cu substrate
Kai Deng, Liang Zhang, Chen Chen, Xiao Lu, Lei Sun, Xing-Yu Guo
Soldering & Surface Mount Technology, Vol. ahead-of-print, No. ahead-of-print, pp.-

This study aims to explore the feasibility of adding Si3N4 nanoparticles to Sn58Bi and provides a theoretical basis for designing and applying new lead-free solder materials for the electronic packaging industry.

In this paper, Sn58Bi-xSi3N4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 Wt.%) was prepared for bonding Cu substrate, and the changes in thermal properties, wettability, microstructure, interfacial intermetallic compound and mechanical properties of the composite solder were systematically studied.

The experiment results demonstrate that including Si3N4 nanoparticles does not significantly impact the melting point of Sn58Bi solder, and the undercooling degree of solder only fluctuates slightly. The molten solder spreading area reached a maximum of 96.17 mm2, raised by 19.41% relative to those without Si3N4, and the wetting angle was the smallest at 0.6 Wt.% of Si3N4, with a minimum value of 8.35°. When the Si3N4 nanoparticles reach 0.6 Wt.%, the solder joint microstructure is significantly refined. Appropriately adding Si3N4 nanoparticles will slightly increase the solder alloy hardness. When the concentration of Si3N4 reaches 0.6 Wt.%, the joints shear strength reached 45.30 MPa, representing a 49.85% increase compared to those without additives. A thorough examination indicates that legitimately incorporating Si3N4 nanoparticles into Sn58Bi solder can enhance its synthetical performance, and 0.6 Wt.% is the best addition amount in our test setting.

In this paper, Si3N4 nanoparticles were incorporated into Sn58Bi solder, and the effects of different contents of Si3N4 nanoparticles on Sn58Bi solder were investigated from various aspects.

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Influence of doping SiN nanoparticles on the properties and microstructure of Sn58Bi solder for connecting Cu substrate10.1108/SSMT-10-2023-0060Soldering & Surface Mount Technology2024-02-15© 2024 Emerald Publishing LimitedKai DengLiang ZhangChen ChenXiao LuLei SunXing-Yu GuoSoldering & Surface Mount Technologyahead-of-printahead-of-print2024-02-1510.1108/SSMT-10-2023-0060https://www.emerald.com/insight/content/doi/10.1108/SSMT-10-2023-0060/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2024 Emerald Publishing Limited
Improvement of SAC0307/Cu column friction plunge micro-welding quality by static constrainthttps://www.emerald.com/insight/content/doi/10.1108/SSMT-12-2023-0070/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatestTo solve the problems caused by using precise molds for copper column positioning in the current column grid array package, this paper aims to optimize the proposed friction plunge micro-welding (FPMW) technology without mold assistance, to overcome the problems of low interfacial bonding strength, shrinkage cavities and flash defects caused by the low hold-tight force of solder on the copper column. A pressurizing device installed under the drill chuck of the friction welding machine is designed, which is used to apply a static constraint to the solder ball obliquely downward to increase the hold-tight force of the peripheral solder on the copper column during welding and promote the friction metallurgical connection between them. The results show that the application of static constraint during welding can increase the compactness of the solder near the friction interface and effectively inhibit occurrences of flash, shrinkage cavities and crystal defects such as vacancies. Therefore, compared with the unconstrained (UC) FPMW, the average strength of the statically constrained (SC) FPMW joints and aged SC-FPMW joints can be increased by 51.1% and 122.6%, and the problem of the excessive growth of the interfacial connection layer in the UC-FPMW joints during aging can be effectively avoided. The application of static constraint effectively inhibits the occurrence of defects such as shrinkage cavities, vacancies and flash in FPMW joints, and the welding quality is significantly improved.Improvement of SAC0307/Cu column friction plunge micro-welding quality by static constraint
Zhenkun Li, Zhili Zhao, Jinliang Liu, Xin Ding
Soldering & Surface Mount Technology, Vol. ahead-of-print, No. ahead-of-print, pp.-

To solve the problems caused by using precise molds for copper column positioning in the current column grid array package, this paper aims to optimize the proposed friction plunge micro-welding (FPMW) technology without mold assistance, to overcome the problems of low interfacial bonding strength, shrinkage cavities and flash defects caused by the low hold-tight force of solder on the copper column.

A pressurizing device installed under the drill chuck of the friction welding machine is designed, which is used to apply a static constraint to the solder ball obliquely downward to increase the hold-tight force of the peripheral solder on the copper column during welding and promote the friction metallurgical connection between them.

The results show that the application of static constraint during welding can increase the compactness of the solder near the friction interface and effectively inhibit occurrences of flash, shrinkage cavities and crystal defects such as vacancies. Therefore, compared with the unconstrained (UC) FPMW, the average strength of the statically constrained (SC) FPMW joints and aged SC-FPMW joints can be increased by 51.1% and 122.6%, and the problem of the excessive growth of the interfacial connection layer in the UC-FPMW joints during aging can be effectively avoided.

The application of static constraint effectively inhibits the occurrence of defects such as shrinkage cavities, vacancies and flash in FPMW joints, and the welding quality is significantly improved.

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Improvement of SAC0307/Cu column friction plunge micro-welding quality by static constraint10.1108/SSMT-12-2023-0070Soldering & Surface Mount Technology2024-01-31© 2024 Emerald Publishing LimitedZhenkun LiZhili ZhaoJinliang LiuXin DingSoldering & Surface Mount Technologyahead-of-printahead-of-print2024-01-3110.1108/SSMT-12-2023-0070https://www.emerald.com/insight/content/doi/10.1108/SSMT-12-2023-0070/full/html?utm_source=rss&utm_medium=feed&utm_campaign=rss_journalLatest© 2024 Emerald Publishing Limited