Pub Date : 2020-09-23DOI: 10.1108/SSMT-06-2020-0025
Wenhui Cai, F. Huang, Kai Liu, M. Alaazim
Purpose As in real applications several alternating current (AC) currents may be injected to the electronic devices, this study aims to analyze their effects on the lifetime of the solder joints and, consequently, shed the light on these effects at the design phase for other researchers to consider. Design/methodology/approach In this paper, the authors investigated on current waveform shapes on the performance and reliability of the solder joints in electronic package. Three common and extensively used current shapes in several simulations and experiments were selected to study their effects on the solder joint performance. Findings The results demonstrate a sever thermal swing and stress fluctuation in the solder joint induced in the case of triangle current type because the critical states lack any relaxation time. In fact, the stress intensification in the solder under application of the triangle current type has been shown to contribute to increasing brittle intermetallic compounds. An accelerated increase of on-state voltage of power semiconductor was also observed in under application of the triangle current type. Originality/value The originality of this paper is confirmed.
{"title":"An investigation on function of current type on solder joint degradation in electronic packages","authors":"Wenhui Cai, F. Huang, Kai Liu, M. Alaazim","doi":"10.1108/SSMT-06-2020-0025","DOIUrl":"https://doi.org/10.1108/SSMT-06-2020-0025","url":null,"abstract":"\u0000Purpose\u0000As in real applications several alternating current (AC) currents may be injected to the electronic devices, this study aims to analyze their effects on the lifetime of the solder joints and, consequently, shed the light on these effects at the design phase for other researchers to consider.\u0000\u0000\u0000Design/methodology/approach\u0000In this paper, the authors investigated on current waveform shapes on the performance and reliability of the solder joints in electronic package. Three common and extensively used current shapes in several simulations and experiments were selected to study their effects on the solder joint performance.\u0000\u0000\u0000Findings\u0000The results demonstrate a sever thermal swing and stress fluctuation in the solder joint induced in the case of triangle current type because the critical states lack any relaxation time. In fact, the stress intensification in the solder under application of the triangle current type has been shown to contribute to increasing brittle intermetallic compounds. An accelerated increase of on-state voltage of power semiconductor was also observed in under application of the triangle current type.\u0000\u0000\u0000Originality/value\u0000The originality of this paper is confirmed.\u0000","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/SSMT-06-2020-0025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48499103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-21DOI: 10.1108/SSMT-12-2019-0043
Rui Xi, Jiangyou Yu, L. Cao, Xiaojiang Zheng, Jun Guo
Purpose Most solder paste printers are configured to periodically clean the stencil to maintain printing quality. However, a periodical cleaning control may result in excessive cleaning operations. The purpose of this paper is to develop a control method to schedule stencil cleaning operations appropriately. Design/methodology/approach A hybrid failure rate model of the stencil printing process with age reduction factor and failure rate increase factor is presented. A stencil cleaning policy based on system reliability is introduced. An optimization model used to derive the optimal stencil cleaning schedule is provided. Findings An aperiodic stencil cleaning control with good adaptability is achieved. A comparative analysis indicates that aperiodic control has better printing system reliability than traditional periodical control under the same cleaning resource consumption. Originality/value Periodical cleaning control commonly used in industrial printing process often results in excessive cleaning operations. By incorporating the printing system reliability, this paper develops an aperiodic stencil cleaning control method based on hybrid failure rate model of the stencil printing process. It helps to reduce unnecessary cleaning operations while keeping printing quality stable.
{"title":"Cleaning control of stencil printing subject to performance deterioration","authors":"Rui Xi, Jiangyou Yu, L. Cao, Xiaojiang Zheng, Jun Guo","doi":"10.1108/SSMT-12-2019-0043","DOIUrl":"https://doi.org/10.1108/SSMT-12-2019-0043","url":null,"abstract":"\u0000Purpose\u0000Most solder paste printers are configured to periodically clean the stencil to maintain printing quality. However, a periodical cleaning control may result in excessive cleaning operations. The purpose of this paper is to develop a control method to schedule stencil cleaning operations appropriately.\u0000\u0000\u0000Design/methodology/approach\u0000A hybrid failure rate model of the stencil printing process with age reduction factor and failure rate increase factor is presented. A stencil cleaning policy based on system reliability is introduced. An optimization model used to derive the optimal stencil cleaning schedule is provided.\u0000\u0000\u0000Findings\u0000An aperiodic stencil cleaning control with good adaptability is achieved. A comparative analysis indicates that aperiodic control has better printing system reliability than traditional periodical control under the same cleaning resource consumption.\u0000\u0000\u0000Originality/value\u0000Periodical cleaning control commonly used in industrial printing process often results in excessive cleaning operations. By incorporating the printing system reliability, this paper develops an aperiodic stencil cleaning control method based on hybrid failure rate model of the stencil printing process. It helps to reduce unnecessary cleaning operations while keeping printing quality stable.\u0000","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/SSMT-12-2019-0043","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45291631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-07DOI: 10.1108/ssmt-05-2020-0017
Fei Chong Ng, M. Zawawi, M. A. Abas
Purpose The purpose of the study is to investigate the spatial aspects of underfill flow during the flip-chip encapsulation process, for instance, meniscus evolution and contact line jump (CLJ). Furthermore, a spatial-based void formation mechanism during the underfill flow was formulated. Design/methodology/approach The meniscus evolution of underfill fluid subtended between the bump array and the CLJ phenomenon were visualized numerically using the micro-mesh unit cell approach. Additionally, the meniscus evolution and CLJ phenomenon were modelled analytically based on the formulation of capillary physics. Meanwhile, the mechanism of void formation was explained numerically and analytically. Findings Both the proposed analytical and current numerical findings achieved great consensus and were well-validated experimentally. The variation effects of bump pitch on the spatial aspects were analyzed and found that the meniscus arc radius and filling distance increase with the pitch, while the subtended angle of meniscus arc is invariant with the pitch size. For larger pitch, the jump occurs further away from the bump entrance and takes longer time to attain the equilibrium meniscus. This inferred that the concavity of meniscus arc was influenced by the bump pitch. On the voiding mechanism, air void was formed from the air entrapment because of the fluid-bump interaction. Smaller voids tend to merge into a bigger void through necking and, subsequently, propagate along the underfill flow. Practical implications The microscopic spatial analysis of underfill flow would explain fundamentally how the bump design will affect the macroscopic filling time. This not only provides alternative visualization tool to analyze flow pattern in the industry but also enables the development of accurate analytical filling time model. Moreover, the void formation mechanism gave substantial insights to understand the root causes of void defects and allow possible solutions to be formulated to tackle this issue. Additionally, the microfluidics sector could also benefit from these spatial analysis insights. Originality/value Spatial analysis on underfill flow is scarcely conducted, as the past research studies mainly emphasized on the temporal aspects. Additionally, this work presented a new mechanism on the void formation based on the fluid-bump interaction, in which the formation and propagation of micro-voids were numerically visualized for the first time. The findings from current work provided fundamental information on the flow interaction between underfill fluid and solder bump to the package designers for optimization work and process enhancement.
{"title":"Spatial analysis of underfill flow in flip-chip encapsulation","authors":"Fei Chong Ng, M. Zawawi, M. A. Abas","doi":"10.1108/ssmt-05-2020-0017","DOIUrl":"https://doi.org/10.1108/ssmt-05-2020-0017","url":null,"abstract":"\u0000Purpose\u0000The purpose of the study is to investigate the spatial aspects of underfill flow during the flip-chip encapsulation process, for instance, meniscus evolution and contact line jump (CLJ). Furthermore, a spatial-based void formation mechanism during the underfill flow was formulated.\u0000\u0000\u0000Design/methodology/approach\u0000The meniscus evolution of underfill fluid subtended between the bump array and the CLJ phenomenon were visualized numerically using the micro-mesh unit cell approach. Additionally, the meniscus evolution and CLJ phenomenon were modelled analytically based on the formulation of capillary physics. Meanwhile, the mechanism of void formation was explained numerically and analytically.\u0000\u0000\u0000Findings\u0000Both the proposed analytical and current numerical findings achieved great consensus and were well-validated experimentally. The variation effects of bump pitch on the spatial aspects were analyzed and found that the meniscus arc radius and filling distance increase with the pitch, while the subtended angle of meniscus arc is invariant with the pitch size. For larger pitch, the jump occurs further away from the bump entrance and takes longer time to attain the equilibrium meniscus. This inferred that the concavity of meniscus arc was influenced by the bump pitch. On the voiding mechanism, air void was formed from the air entrapment because of the fluid-bump interaction. Smaller voids tend to merge into a bigger void through necking and, subsequently, propagate along the underfill flow.\u0000\u0000\u0000Practical implications\u0000The microscopic spatial analysis of underfill flow would explain fundamentally how the bump design will affect the macroscopic filling time. This not only provides alternative visualization tool to analyze flow pattern in the industry but also enables the development of accurate analytical filling time model. Moreover, the void formation mechanism gave substantial insights to understand the root causes of void defects and allow possible solutions to be formulated to tackle this issue. Additionally, the microfluidics sector could also benefit from these spatial analysis insights.\u0000\u0000\u0000Originality/value\u0000Spatial analysis on underfill flow is scarcely conducted, as the past research studies mainly emphasized on the temporal aspects. Additionally, this work presented a new mechanism on the void formation based on the fluid-bump interaction, in which the formation and propagation of micro-voids were numerically visualized for the first time. The findings from current work provided fundamental information on the flow interaction between underfill fluid and solder bump to the package designers for optimization work and process enhancement.\u0000","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/ssmt-05-2020-0017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47169189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-06DOI: 10.1108/ssmt-03-2020-0012
Przemysław Ptak, K. Górecki, A. Skwarek, K. Witek, J. Tarasiuk
This paper aims to present the results of investigations that show the influence of soldering process parameters on the optical and thermal parameters of power LEDs.,The power LEDs were soldered onto metal core printed circuit board (MCPCB) substrates in different soldering ovens: batch and tunnel types, characterized by different thermal profiles. Three types of solder pastes based on Sn99Ag0.3Cu0.7 with the addition of TiO2 were used. The thermal and optical parameters of the diodes were measured using classical indirect electrical methods. The results of measurements obtained were compared and discussed.,It was shown that the type of oven and soldering thermal profile considerably influence the effectiveness of the removal of heat generated in the LEDs tested. This influence is characterized by thermal resistance changes. The differences between the values of this parameter can exceed 20%. This value also depends on the composition of the soldering paste. The differences between the diodes tested can exceed 15%. It was also shown that the luminous flux emitted by the diode depends on the soldering process used.,The results obtained could be useful for process design engineers for assembling power LEDs for MCPCBs and for designers of solid-state light sources.,This paper presents the results of investigations into the influence of the soldering profiles and soldering pastes used on the effectiveness of the removal of heat generated in power LEDs. It shows and discusses how the factors mentioned above influence the thermal resistance of the LEDs and optical parameters that characterize the light emitted.
{"title":"The influence of soldering process parameters on the optical and thermal properties of power LEDs","authors":"Przemysław Ptak, K. Górecki, A. Skwarek, K. Witek, J. Tarasiuk","doi":"10.1108/ssmt-03-2020-0012","DOIUrl":"https://doi.org/10.1108/ssmt-03-2020-0012","url":null,"abstract":"This paper aims to present the results of investigations that show the influence of soldering process parameters on the optical and thermal parameters of power LEDs.,The power LEDs were soldered onto metal core printed circuit board (MCPCB) substrates in different soldering ovens: batch and tunnel types, characterized by different thermal profiles. Three types of solder pastes based on Sn99Ag0.3Cu0.7 with the addition of TiO2 were used. The thermal and optical parameters of the diodes were measured using classical indirect electrical methods. The results of measurements obtained were compared and discussed.,It was shown that the type of oven and soldering thermal profile considerably influence the effectiveness of the removal of heat generated in the LEDs tested. This influence is characterized by thermal resistance changes. The differences between the values of this parameter can exceed 20%. This value also depends on the composition of the soldering paste. The differences between the diodes tested can exceed 15%. It was also shown that the luminous flux emitted by the diode depends on the soldering process used.,The results obtained could be useful for process design engineers for assembling power LEDs for MCPCBs and for designers of solid-state light sources.,This paper presents the results of investigations into the influence of the soldering profiles and soldering pastes used on the effectiveness of the removal of heat generated in power LEDs. It shows and discusses how the factors mentioned above influence the thermal resistance of the LEDs and optical parameters that characterize the light emitted.","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":"32 1","pages":"191-199"},"PeriodicalIF":2.0,"publicationDate":"2020-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/ssmt-03-2020-0012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41459605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-14DOI: 10.1108/ssmt-03-2019-0009
Rabiatul Adawiyah Mohamed Anuar, S. A. Osman
Purpose The surface finish is an essential step in printed circuit boards design because it provides a solderable surface for electronic components. The purpose of this study to investigate the effects of different surface finishes during the soldering and ageing process. Design/methodology/approach The solder joints of Sn-4.0Ag-0.5Cu/Cu and Sn-4.0Ag-0.5Cu/electroless nickel/immersion silver (ENImAg) were investigated in terms of intermetallic (IMC) thickness, morphology and shear strength. The microstructure and compositions of solder joints are observed, and analyzed by using scanning electron microscopy (SEM-EDX) and optical microscope (OM). Findings Compounds of Cu6Sn5 and (Cu, Ni)6Sn5 IMC were formed in SAC405/Cu and SAC405/ENImAg, respectively, as-reflowed. When the sample was exposed to ageing, new layers of Cu3Sn and (Ni, Cu)3Sn5 were observed at the interface. Analogous growth in the thickness of the IMC layer and increased grains size commensurate with ageing time. The results equally revealed an increase in shear strength of SAC405/ENImAg because of the thin layer of IMC and surface finish used compared to SAC405/Cu. Hence, a ductile fracture was observed at the bulk solder. Overall, the ENImAg surface finish showed excellent performance of solder joints than that of bare Cu. Originality/value The novel surface finish (ENImAg) has been developed and optimized. This alternative lead-free surface finish solved the challenges in electroless nickel/immersion gold and reduced cost without affecting the performance.
{"title":"The formation of intermetallic layer structure of SAC405/Cu and SAC405/ENImAg solder joint interfaces","authors":"Rabiatul Adawiyah Mohamed Anuar, S. A. Osman","doi":"10.1108/ssmt-03-2019-0009","DOIUrl":"https://doi.org/10.1108/ssmt-03-2019-0009","url":null,"abstract":"Purpose The surface finish is an essential step in printed circuit boards design because it provides a solderable surface for electronic components. The purpose of this study to investigate the effects of different surface finishes during the soldering and ageing process. Design/methodology/approach The solder joints of Sn-4.0Ag-0.5Cu/Cu and Sn-4.0Ag-0.5Cu/electroless nickel/immersion silver (ENImAg) were investigated in terms of intermetallic (IMC) thickness, morphology and shear strength. The microstructure and compositions of solder joints are observed, and analyzed by using scanning electron microscopy (SEM-EDX) and optical microscope (OM). Findings Compounds of Cu6Sn5 and (Cu, Ni)6Sn5 IMC were formed in SAC405/Cu and SAC405/ENImAg, respectively, as-reflowed. When the sample was exposed to ageing, new layers of Cu3Sn and (Ni, Cu)3Sn5 were observed at the interface. Analogous growth in the thickness of the IMC layer and increased grains size commensurate with ageing time. The results equally revealed an increase in shear strength of SAC405/ENImAg because of the thin layer of IMC and surface finish used compared to SAC405/Cu. Hence, a ductile fracture was observed at the bulk solder. Overall, the ENImAg surface finish showed excellent performance of solder joints than that of bare Cu. Originality/value The novel surface finish (ENImAg) has been developed and optimized. This alternative lead-free surface finish solved the challenges in electroless nickel/immersion gold and reduced cost without affecting the performance.","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/ssmt-03-2019-0009","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49321964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-13DOI: 10.1108/ssmt-10-2019-0033
Faisal Rehman, Rafiq Asghar, Kashif Iqbal, Ali Aman, Agha Ali Nawaz
Purpose In surface mount assembly (SMA) process, small components are subjected to high temperature variations, which result in components’ deformation and cracking. Because of this phenomenon, cracks are formed in the body of carbonyl powder ceramic inductor (CPCI) in the preheat and cooling stages of the reflow oven. These cracks become the main cause of board failure in the ageing process. The purpose of this paper is to ascertain the thermal stress, thermal expansion of carbonyl iron ceramics and its effects on crack commencement and proliferation in the preheat stage of reflow oven. Moreover, this paper also categorized and suggested important parameters of reflow profile that could be used to eliminate these thermal shock failures. Design/methodology/approach In this paper, two different reflow profiles were studied that evaluate the thermal shock of CPCI during varying ΔT at the preheat zone of the reflow oven. In the first profile, the change in temperature ΔT at preheat zone was set to 3.26°C/s, which has resulted in a number of device failures because of migration of micro cracks through the CPCI. In the second profile, this ΔT at preheat stage is minimized to 2.06°C/s that eliminated the thermal stresses; hence, the failure rates were significantly reduced. Findings TMPC0618H series lead (Pb)-free CPCI is selected for this study and its thermal expansion and thermal shock are observed in the reflow process. It is inferred from the results that high ΔT at preheat zone generates cracks in the carbonyl powder-type ceramics that cause device failure in the board ageing process. Comparing materials, carbonyl powder ceramic components are less resistant to thermal shock and a lower rate of temperature change is desirable. Originality/value The proposed study presents an experimental analysis for mitigating the thermal shock defects. The realization of the proposed approach is validated with experimental data from the printed circuit boards manufacturing process.
{"title":"An experimental study of carbonyl powder power inductor cracking during reflow process","authors":"Faisal Rehman, Rafiq Asghar, Kashif Iqbal, Ali Aman, Agha Ali Nawaz","doi":"10.1108/ssmt-10-2019-0033","DOIUrl":"https://doi.org/10.1108/ssmt-10-2019-0033","url":null,"abstract":"\u0000Purpose\u0000In surface mount assembly (SMA) process, small components are subjected to high temperature variations, which result in components’ deformation and cracking. Because of this phenomenon, cracks are formed in the body of carbonyl powder ceramic inductor (CPCI) in the preheat and cooling stages of the reflow oven. These cracks become the main cause of board failure in the ageing process. The purpose of this paper is to ascertain the thermal stress, thermal expansion of carbonyl iron ceramics and its effects on crack commencement and proliferation in the preheat stage of reflow oven. Moreover, this paper also categorized and suggested important parameters of reflow profile that could be used to eliminate these thermal shock failures.\u0000\u0000\u0000Design/methodology/approach\u0000In this paper, two different reflow profiles were studied that evaluate the thermal shock of CPCI during varying ΔT at the preheat zone of the reflow oven. In the first profile, the change in temperature ΔT at preheat zone was set to 3.26°C/s, which has resulted in a number of device failures because of migration of micro cracks through the CPCI. In the second profile, this ΔT at preheat stage is minimized to 2.06°C/s that eliminated the thermal stresses; hence, the failure rates were significantly reduced.\u0000\u0000\u0000Findings\u0000TMPC0618H series lead (Pb)-free CPCI is selected for this study and its thermal expansion and thermal shock are observed in the reflow process. It is inferred from the results that high ΔT at preheat zone generates cracks in the carbonyl powder-type ceramics that cause device failure in the board ageing process. Comparing materials, carbonyl powder ceramic components are less resistant to thermal shock and a lower rate of temperature change is desirable.\u0000\u0000\u0000Originality/value\u0000The proposed study presents an experimental analysis for mitigating the thermal shock defects. The realization of the proposed approach is validated with experimental data from the printed circuit boards manufacturing process.\u0000","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/ssmt-10-2019-0033","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45532786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-30DOI: 10.1108/ssmt-11-2019-0035
N. Ismail, A. Jalar, M. A. Bakar, N. Safee, W. Yusoff, Ariffin Ismail
Purpose The purpose of this paper is to investigate the effect of carbon nanotube (CNT) addition on microstructure, interfacial intermetallic compound (IMC) layer and micromechanical properties of Sn-3.0Ag-0.5Cu (SAC305)/CNT/Cu solder joint under blast wave condition. This work is an extension from the previous study of microstructural evolution and hardness properties of Sn-Ag-Cu (SAC) solder under blast wave condition. Design/methodology/approach SAC/CNT solder pastes were manufactured by mixing of SAC solder powder, fluxes and CNT with 0.02 and 0.04 by weight percentage (Wt.%) separately. This solder paste then printed on the printed circuit board (PCB) with the copper surface finish. Printed samples underwent reflow soldering to form the solder joint. Soldered samples then exposed to the open field air blast test with different weight charges of explosives. Microstructure, interfacial IMC layer and micromechanical behavior of SAC/CNT solder joints after blast test were observed and analyzed via optical microscope, field emission scanning microscope and nanoindentation. Findings Exposure to the blast wave induced the microstructure instability of SAC305/Cu and SAC/CNT/Cu solder joint. Interfacial IMC layer thickness and hardness properties increases with increase in explosive weight. The existence of CNT in the SAC305 solder system is increasing the resistance of solder joint to the blast wave. Originality/value Response of micromechanical properties of SAC305/CNT/Cu solder joint has been identified and provided a fundamental understanding of reliability solder joint, especially in extreme conditions such as for military applications.
{"title":"Microstructural evolution and micromechanical properties of SAC305/CNT/CU solder joint under blast wave condition","authors":"N. Ismail, A. Jalar, M. A. Bakar, N. Safee, W. Yusoff, Ariffin Ismail","doi":"10.1108/ssmt-11-2019-0035","DOIUrl":"https://doi.org/10.1108/ssmt-11-2019-0035","url":null,"abstract":"\u0000Purpose\u0000The purpose of this paper is to investigate the effect of carbon nanotube (CNT) addition on microstructure, interfacial intermetallic compound (IMC) layer and micromechanical properties of Sn-3.0Ag-0.5Cu (SAC305)/CNT/Cu solder joint under blast wave condition. This work is an extension from the previous study of microstructural evolution and hardness properties of Sn-Ag-Cu (SAC) solder under blast wave condition.\u0000\u0000\u0000Design/methodology/approach\u0000SAC/CNT solder pastes were manufactured by mixing of SAC solder powder, fluxes and CNT with 0.02 and 0.04 by weight percentage (Wt.%) separately. This solder paste then printed on the printed circuit board (PCB) with the copper surface finish. Printed samples underwent reflow soldering to form the solder joint. Soldered samples then exposed to the open field air blast test with different weight charges of explosives. Microstructure, interfacial IMC layer and micromechanical behavior of SAC/CNT solder joints after blast test were observed and analyzed via optical microscope, field emission scanning microscope and nanoindentation.\u0000\u0000\u0000Findings\u0000Exposure to the blast wave induced the microstructure instability of SAC305/Cu and SAC/CNT/Cu solder joint. Interfacial IMC layer thickness and hardness properties increases with increase in explosive weight. The existence of CNT in the SAC305 solder system is increasing the resistance of solder joint to the blast wave.\u0000\u0000\u0000Originality/value\u0000Response of micromechanical properties of SAC305/CNT/Cu solder joint has been identified and provided a fundamental understanding of reliability solder joint, especially in extreme conditions such as for military applications.\u0000","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/ssmt-11-2019-0035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43512467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-29DOI: 10.1108/ssmt-03-2020-0013
C. Morando, O. Fornaro
Purpose The purpose of this paper is to carry out a study of the evolution of the microstructure and the microhardness of Sn-Cu-Ag alloys from as-cast condition and under artificial isothermal aging at different temperatures (100ºC and 180ºC) for a treatment time up to 500 h. A comparison with Sn-37% Pb eutectic solder samples was also made. Design/methodology/approach Sn-3.5%Ag, Sn-0.7%Cu and Sn-3.5%Ag-0.9%Cu were poured in two different cooling rate conditions and then aged at 100ºC (373ºK) and 180 °C (453ºK) during 500 h. Microstructural changes were observed by optical microscopy, scanning electron micrograph and energy dispersive X-ray microanalysis. Differential scanning calorimetry technique (DSC) was also used to confirm the obtained results. Findings A decrease up to 20% in microhardness respect to the value of the as-cast alloy was observed for both aging temperatures. These changes can be explained considering the coarsening and recrystallization of Sn dendrites present in the microstructures of all the systems studied. Originality/value There is no evidence of dissolution or precipitation of new phases in the range of studied temperatures that could be detected by DSC calorimetry technique. The acting mechanisms must be the result of coarsening of Sn dendrites and the residual stresses relaxation during the first stages of the isothermal aging.
{"title":"Influence of aging on microstructure and hardness of lead-free solder alloys","authors":"C. Morando, O. Fornaro","doi":"10.1108/ssmt-03-2020-0013","DOIUrl":"https://doi.org/10.1108/ssmt-03-2020-0013","url":null,"abstract":"\u0000Purpose\u0000The purpose of this paper is to carry out a study of the evolution of the microstructure and the microhardness of Sn-Cu-Ag alloys from as-cast condition and under artificial isothermal aging at different temperatures (100ºC and 180ºC) for a treatment time up to 500 h. A comparison with Sn-37% Pb eutectic solder samples was also made.\u0000\u0000\u0000Design/methodology/approach\u0000Sn-3.5%Ag, Sn-0.7%Cu and Sn-3.5%Ag-0.9%Cu were poured in two different cooling rate conditions and then aged at 100ºC (373ºK) and 180 °C (453ºK) during 500 h. Microstructural changes were observed by optical microscopy, scanning electron micrograph and energy dispersive X-ray microanalysis. Differential scanning calorimetry technique (DSC) was also used to confirm the obtained results.\u0000\u0000\u0000Findings\u0000A decrease up to 20% in microhardness respect to the value of the as-cast alloy was observed for both aging temperatures. These changes can be explained considering the coarsening and recrystallization of Sn dendrites present in the microstructures of all the systems studied.\u0000\u0000\u0000Originality/value\u0000There is no evidence of dissolution or precipitation of new phases in the range of studied temperatures that could be detected by DSC calorimetry technique. The acting mechanisms must be the result of coarsening of Sn dendrites and the residual stresses relaxation during the first stages of the isothermal aging.\u0000","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/ssmt-03-2020-0013","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43615491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-29DOI: 10.1108/ssmt-03-2020-0011
Wenjie Chen, Nian Cai, Huiheng Wang, Lin Jianfa, Han Wang
Purpose Automatic optical inspection (AOI) systems have been widely used in many fields to evaluate the qualities of products at the end of the production line. The purpose of this paper is to propose a local-to-global ensemble learning method for the AOI system based on to inspect integrated circuit (IC) solder joints defects. Design/methodology/approach In the proposed method, the locally statistically modeling stage and the globally ensemble learning stage are involved to tackle the inspection problem. At the former stage, the improved visual background extraction–based algorithm is used for locally statistically modeling to grasp tiny appearance differences between the IC solder joints to achieve potential defect images for the subsequent stage. At the latter stage, mean unqualified probability is introduced based on a novel ensemble learning, in which an adaptive weighted strategy is proposed for revealing different contributions of the base classifier to the inspection performance. Findings Experimental results demonstrate that the proposed method achieves better inspection performance with an acceptable inspection time compared with some state-of-the-art methods. Originality/value The approach is a promising method for IC solder joint inspection, which can simultaneously grasp the local characteristics of IC solder joints and reveal inherently global relationships between IC solder joints.
{"title":"Automatic optical inspection system for IC solder joint based on local-to-global ensemble learning","authors":"Wenjie Chen, Nian Cai, Huiheng Wang, Lin Jianfa, Han Wang","doi":"10.1108/ssmt-03-2020-0011","DOIUrl":"https://doi.org/10.1108/ssmt-03-2020-0011","url":null,"abstract":"\u0000Purpose\u0000Automatic optical inspection (AOI) systems have been widely used in many fields to evaluate the qualities of products at the end of the production line. The purpose of this paper is to propose a local-to-global ensemble learning method for the AOI system based on to inspect integrated circuit (IC) solder joints defects.\u0000\u0000\u0000Design/methodology/approach\u0000In the proposed method, the locally statistically modeling stage and the globally ensemble learning stage are involved to tackle the inspection problem. At the former stage, the improved visual background extraction–based algorithm is used for locally statistically modeling to grasp tiny appearance differences between the IC solder joints to achieve potential defect images for the subsequent stage. At the latter stage, mean unqualified probability is introduced based on a novel ensemble learning, in which an adaptive weighted strategy is proposed for revealing different contributions of the base classifier to the inspection performance.\u0000\u0000\u0000Findings\u0000Experimental results demonstrate that the proposed method achieves better inspection performance with an acceptable inspection time compared with some state-of-the-art methods.\u0000\u0000\u0000Originality/value\u0000The approach is a promising method for IC solder joint inspection, which can simultaneously grasp the local characteristics of IC solder joints and reveal inherently global relationships between IC solder joints.\u0000","PeriodicalId":49499,"journal":{"name":"Soldering & Surface Mount Technology","volume":" ","pages":""},"PeriodicalIF":2.0,"publicationDate":"2020-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1108/ssmt-03-2020-0011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46190998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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