The electromigration (EM) damage is becoming a severe problem in the printed flexible electronics as the printed circuits are fabricated thinner and thinner due to the development of printing technology. In this work, the EM behavior of printed silver wires was investigated by EM experiments and numerical simulations. The EM tests showed that voids are generated in the cathode area and hillocks are formed in the anode area for a wire with a small length. However, with the increase of wire length, hillocks tend to occur on the two sides of the silver wire middle part. The results of numerical simulations based on the atomic flux divergence (AFD) method revealed that the formation of the hillocks on the printed wire is caused by not only the mechanism of electron wind, but also the strong temperature gradient along the wire length and width direction. Also, it can be concluded that the temperature gradient induced by Joule heating plays a more important role than electron wind in the atomic migration of the printed silver wire subjected to a high current density. The influence of the printed silver wire size on the EM behavior was also analyzed by numerical simulation, and the results demonstrated that the printed silver wires with a larger length and a smaller width-to-thickness ratio are more likely to develop hillocks on the two sides of silver wire middle part while subjected to a high current density.
{"title":"Experimental and Numerical Investigation of Electromigration Behavior of Printed Silver Wire Under High Current Density","authors":"Haibin Zhang, Quanshe Sun, Zhidan Sun, Yebo Lu","doi":"10.1115/1.4055469","DOIUrl":"https://doi.org/10.1115/1.4055469","url":null,"abstract":"\u0000 The electromigration (EM) damage is becoming a severe problem in the printed flexible electronics as the printed circuits are fabricated thinner and thinner due to the development of printing technology. In this work, the EM behavior of printed silver wires was investigated by EM experiments and numerical simulations. The EM tests showed that voids are generated in the cathode area and hillocks are formed in the anode area for a wire with a small length. However, with the increase of wire length, hillocks tend to occur on the two sides of the silver wire middle part. The results of numerical simulations based on the atomic flux divergence (AFD) method revealed that the formation of the hillocks on the printed wire is caused by not only the mechanism of electron wind, but also the strong temperature gradient along the wire length and width direction. Also, it can be concluded that the temperature gradient induced by Joule heating plays a more important role than electron wind in the atomic migration of the printed silver wire subjected to a high current density. The influence of the printed silver wire size on the EM behavior was also analyzed by numerical simulation, and the results demonstrated that the printed silver wires with a larger length and a smaller width-to-thickness ratio are more likely to develop hillocks on the two sides of silver wire middle part while subjected to a high current density.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43464868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin Wei, M. Belhadi, S. Hamasha, Ali Alahmer, R. Zhao, B. Prorok, N. Sakib
The reliability of SAC-based solder alloys has been extensively investigated after the prohibition of lead in the electronics industry owing to their toxicity. Low-temperature solder (LTS) alloys have recently received considerable attention because of their low cost and reduced defects in complex assemblies. The shear and fatigue properties of individual solder joints were tested using an Instron micromechanical testing system in this research. Two novel solder alloys (Sn-58Bi-0.5Sb-0.15Ni and Sn-42Bi) with low melting temperatures were examined and compared with Sn-3.5Ag and Sn-3.0Ag-0.8Cu-3.0Bi. The surface finish was electroless nickel-immersion gold (ENIG) during the test. Shear testing was conducted at three strain rates, and the shear strength of each solder alloy was measured. A constant strain rate was used for the cyclic fatigue experiments. The fatigue life of each alloy was determined for various stress amplitudes. The failure mechanism in shear and fatigue tests were characterized using scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS). The results revealed that Sn-3.0Ag-0.8Cu-3.0Bi had superior shear and fatigue properties compared to other alloys, but was more susceptible to brittle failure. The shear strain rate affected the failure modes of Sn-3.0Ag-0.8Cu-3.0Bi, Sn-58Bi-0.5Sb-0.15Ni, and Sn-42Bi; however, Sn-3.5Ag was found to be insensitive. Several failure modes were detected for Sn-3.5Ag in both shear strength and fatigue tests.
{"title":"Shear and Fatigue Properties of Lead-Free Solder Joints: Modeling and Microstructure Analysis","authors":"Xin Wei, M. Belhadi, S. Hamasha, Ali Alahmer, R. Zhao, B. Prorok, N. Sakib","doi":"10.1115/1.4055318","DOIUrl":"https://doi.org/10.1115/1.4055318","url":null,"abstract":"\u0000 The reliability of SAC-based solder alloys has been extensively investigated after the prohibition of lead in the electronics industry owing to their toxicity. Low-temperature solder (LTS) alloys have recently received considerable attention because of their low cost and reduced defects in complex assemblies. The shear and fatigue properties of individual solder joints were tested using an Instron micromechanical testing system in this research. Two novel solder alloys (Sn-58Bi-0.5Sb-0.15Ni and Sn-42Bi) with low melting temperatures were examined and compared with Sn-3.5Ag and Sn-3.0Ag-0.8Cu-3.0Bi. The surface finish was electroless nickel-immersion gold (ENIG) during the test. Shear testing was conducted at three strain rates, and the shear strength of each solder alloy was measured. A constant strain rate was used for the cyclic fatigue experiments. The fatigue life of each alloy was determined for various stress amplitudes. The failure mechanism in shear and fatigue tests were characterized using scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS). The results revealed that Sn-3.0Ag-0.8Cu-3.0Bi had superior shear and fatigue properties compared to other alloys, but was more susceptible to brittle failure. The shear strain rate affected the failure modes of Sn-3.0Ag-0.8Cu-3.0Bi, Sn-58Bi-0.5Sb-0.15Ni, and Sn-42Bi; however, Sn-3.5Ag was found to be insensitive. Several failure modes were detected for Sn-3.5Ag in both shear strength and fatigue tests.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42250054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Qin, Qi He, Yanpeng Gong, Chuantao Hou, Hao Cheng, Tong An, Yanwei Dai, Pei Chen
We introduce a coupled finite and boundary element method for elastic-plastic analysis over multiscale electronic packaging structures. Based on the FE-BE coupling algorithm, an automatic implementation procedure for the coupling of the Abaqus with a self-written elastic BE code is introduced for elastic problems. In the mixed FEM-BEM model, the effective stiffness and effective forces at the interfacial boundary are evaluated by the self-written BE code. Then, the obtained effective stiffness and effective forces are assembled to the global FE formulations by using the user subroutine (UEL) in Abaqus. Numerical simulation of structures with plastic deformation, stress concentration, etc. is carried out by using FEM theory. The boundary element method is used for linear elastic domains with large-scale structure. The proposed method offers several key improvements compared with current analysis methods available for multi-scale electronic packaging structures. The benefits are: (i) the powerful pre- and post-processing of ABAQUS; (ii) the higher accuracy of the solution; (iii) the computational cost and time can be reduced by using the scheme; and (iv) solving systems with infinite extension by using the BEM as a supplement. Furthermore, we demonstrate the ability of the proposed approach to handle multiscale structures in electronic packaging problems.
{"title":"An Automatic Fem-bem Coupling Method for Elastic-plastic Problems of Multiscale Structures in Electronic Packaging","authors":"F. Qin, Qi He, Yanpeng Gong, Chuantao Hou, Hao Cheng, Tong An, Yanwei Dai, Pei Chen","doi":"10.1115/1.4055125","DOIUrl":"https://doi.org/10.1115/1.4055125","url":null,"abstract":"\u0000 We introduce a coupled finite and boundary element method for elastic-plastic analysis over multiscale electronic packaging structures. Based on the FE-BE coupling algorithm, an automatic implementation procedure for the coupling of the Abaqus with a self-written elastic BE code is introduced for elastic problems. In the mixed FEM-BEM model, the effective stiffness and effective forces at the interfacial boundary are evaluated by the self-written BE code. Then, the obtained effective stiffness and effective forces are assembled to the global FE formulations by using the user subroutine (UEL) in Abaqus. Numerical simulation of structures with plastic deformation, stress concentration, etc. is carried out by using FEM theory. The boundary element method is used for linear elastic domains with large-scale structure. The proposed method offers several key improvements compared with current analysis methods available for multi-scale electronic packaging structures. The benefits are: (i) the powerful pre- and post-processing of ABAQUS; (ii) the higher accuracy of the solution; (iii) the computational cost and time can be reduced by using the scheme; and (iv) solving systems with infinite extension by using the BEM as a supplement. Furthermore, we demonstrate the ability of the proposed approach to handle multiscale structures in electronic packaging problems.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43028168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shuv Dey, Luis Diego Monge Jimenez, J. M. Brown, Y. Joshi
Outdoor digital displays have become increasingly popular and common for smart city applications, and more recently provides a concealment solution and integration point for outdoor communications devices meant to be attached to buildings, streetlamps, or traffic poles. Given the larger energy requirements for powering next generation 5G cellular networks, these devices create unique difficulties in developing and evaluating thermal management solutions. The present study develops and validates the extreme condition transient (ECT) climate model using a CFD/HT numerical model, to evaluate diurnal thermal responses from a representative 5G small cell devices. The model is validated for local conditions present in Atlanta, GA for two unique days. The thermal response from the ECT climate model is presented alongside three real case study locations, Miami, FL, New York City, NY, and Phoenix, AZ.
{"title":"Development and Validation of a Transient Heat Transfer Model for Evaluating Thermal Management Solutions for Packaging Next-Generation Smart City Infrastructure Devices","authors":"Shuv Dey, Luis Diego Monge Jimenez, J. M. Brown, Y. Joshi","doi":"10.1115/1.4055094","DOIUrl":"https://doi.org/10.1115/1.4055094","url":null,"abstract":"\u0000 Outdoor digital displays have become increasingly popular and common for smart city applications, and more recently provides a concealment solution and integration point for outdoor communications devices meant to be attached to buildings, streetlamps, or traffic poles. Given the larger energy requirements for powering next generation 5G cellular networks, these devices create unique difficulties in developing and evaluating thermal management solutions. The present study develops and validates the extreme condition transient (ECT) climate model using a CFD/HT numerical model, to evaluate diurnal thermal responses from a representative 5G small cell devices. The model is validated for local conditions present in Atlanta, GA for two unique days. The thermal response from the ECT climate model is presented alongside three real case study locations, Miami, FL, New York City, NY, and Phoenix, AZ.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45644443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, a novel testing system has been employed to facilitate the estimation of the reliability of solder interconnects under the combined influence of EM and mechanical strain. The system subjects solder interconnects to high current density, elevated ambient temperature, and a constant tensile stress while recording the change in electrical resistance and change in length of the solder over time. The solder samples were created using two copper wires connected by a eutectic Pb/Sn solder ball to imitate flip-chip or BGA packaging interconnects, allowing for controlled testing conditions in order to demonstrate the combined effects of a mechanical load and EM on the lifetime of a solder joint. A significant reduction in lifetime was observed for samples which endured the coupled accelerating factors. Comparing the experimental results of different current densities at different stress levels provided a new outlook on the nature of coupled failure acceleration in solders. This novel test methodology can inform model generation for better anticipating the failure rate of solder interconnects which naturally experience multiple stress inputs during their lifetime.
{"title":"Accelerated Solder Interconnect Testing Under Electromigratory and Mechanical Strain Conditions","authors":"Mahsa Montazeri, Whit Vinson, D. Huitink","doi":"10.1115/1.4055024","DOIUrl":"https://doi.org/10.1115/1.4055024","url":null,"abstract":"\u0000 In this work, a novel testing system has been employed to facilitate the estimation of the reliability of solder interconnects under the combined influence of EM and mechanical strain. The system subjects solder interconnects to high current density, elevated ambient temperature, and a constant tensile stress while recording the change in electrical resistance and change in length of the solder over time. The solder samples were created using two copper wires connected by a eutectic Pb/Sn solder ball to imitate flip-chip or BGA packaging interconnects, allowing for controlled testing conditions in order to demonstrate the combined effects of a mechanical load and EM on the lifetime of a solder joint. A significant reduction in lifetime was observed for samples which endured the coupled accelerating factors. Comparing the experimental results of different current densities at different stress levels provided a new outlook on the nature of coupled failure acceleration in solders. This novel test methodology can inform model generation for better anticipating the failure rate of solder interconnects which naturally experience multiple stress inputs during their lifetime.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48332932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vahideh Radmard, Ahmad R. Gharaibeh, Mohammad I. Tradat, C. H. Hoang, Yaman M. Manaserh, K. Nemati, Scott N. Schiffres, B. Sammakia
More than ever before, data centers must deploy robust thermal solutions to adequately host the high-density and high-performance computing that is in high demand. The newer generation of central processing units (CPUs) and graphics processing units (GPUs) has substantially higher thermal power densities than previous generations. In recent years, more data centers rely on liquid cooling for the high-heat processors inside the servers and air cooling for the remaining low-heat Information Technology Equipment (ITE). This hybrid cooling approach creates a smaller and more efficient data center. The deployment of direct-to-chip cold plate liquid cooling is one of mainstream approaches to providing concentrated cooling to targeted processors. In the current study, a processor level experimental setup was developed to evaluate the cooling performance of a novel Computer Numerical Control (CNC) machined nickel-plated impinging cold plate on a 1 in x 1 in mock heater that represents a functional processing unit. The pressure drop and thermal resistance performance curves of the electroless nickel-plated cold plate are compared to those of a pure copper cold plate. A temperature uniformity analysis is done using CFD and compared to the actual test data. Lastly, the CNC machined pure copper one is compared to other reported cold plates to demonstrate its superiority of the design with respect to the cooling performance.
{"title":"Performance Analysis of Corrosion Resistant Electroless Nickel-Plated Impinging CNC Manufactured Liquid Cooling Cold Plate","authors":"Vahideh Radmard, Ahmad R. Gharaibeh, Mohammad I. Tradat, C. H. Hoang, Yaman M. Manaserh, K. Nemati, Scott N. Schiffres, B. Sammakia","doi":"10.1115/1.4054972","DOIUrl":"https://doi.org/10.1115/1.4054972","url":null,"abstract":"\u0000 More than ever before, data centers must deploy robust thermal solutions to adequately host the high-density and high-performance computing that is in high demand. The newer generation of central processing units (CPUs) and graphics processing units (GPUs) has substantially higher thermal power densities than previous generations. In recent years, more data centers rely on liquid cooling for the high-heat processors inside the servers and air cooling for the remaining low-heat Information Technology Equipment (ITE). This hybrid cooling approach creates a smaller and more efficient data center. The deployment of direct-to-chip cold plate liquid cooling is one of mainstream approaches to providing concentrated cooling to targeted processors. In the current study, a processor level experimental setup was developed to evaluate the cooling performance of a novel Computer Numerical Control (CNC) machined nickel-plated impinging cold plate on a 1 in x 1 in mock heater that represents a functional processing unit. The pressure drop and thermal resistance performance curves of the electroless nickel-plated cold plate are compared to those of a pure copper cold plate. A temperature uniformity analysis is done using CFD and compared to the actual test data. Lastly, the CNC machined pure copper one is compared to other reported cold plates to demonstrate its superiority of the design with respect to the cooling performance.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43563107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Anand model is a unified viscoplastic model which is widely employed to describe the solder material deformation. The parameters in the Anand model for a certain material are usually identified by using the classical method based on two algebraic equations derived from the original differential equation of the Anand model. However, the second algebraic equation describing the relationship between the stress and inelastic strain is obtained with some terms about the unsteady value of internal variable neglected. But the effects induced by the omission of some unsteady terms on the effectiveness of classical method are not researched comprehensively. Therefore, in this paper, the effects of the omitted terms on the accuracy of the classical method are discussed. The inelastic deformation for the material which the second algebraic equation can not describe due to the omission of unsteady terms is presented. The precondition for obtaining accurate results from the second algebraic equation is given out. Two criteria used to judge the effectiveness of the second algebraic equation are derived. To reduce the error related to the second algebraic equation of the classical method for some materials, two alternative identification methods are proposed. By combining the step of solving differential equation and genetic algorithm, the parameters in the Anand model originally identified by the second algebraic equation are determined in the process of the two proposed methods. The effectiveness of the two alternative methods is presented by identifying the material Anand parameters where the classical method can not be applied.
{"title":"The Discussion About the Identification of the Anand Model Parameters and Two Alternative Identification Methods","authors":"Yuqian Xu, Qiwen Zeng, Yuexing Wang, Mingyong Wu, Xiangyu Chen, Gang Chen","doi":"10.1115/1.4054821","DOIUrl":"https://doi.org/10.1115/1.4054821","url":null,"abstract":"\u0000 The Anand model is a unified viscoplastic model which is widely employed to describe the solder material deformation. The parameters in the Anand model for a certain material are usually identified by using the classical method based on two algebraic equations derived from the original differential equation of the Anand model. However, the second algebraic equation describing the relationship between the stress and inelastic strain is obtained with some terms about the unsteady value of internal variable neglected. But the effects induced by the omission of some unsteady terms on the effectiveness of classical method are not researched comprehensively. Therefore, in this paper, the effects of the omitted terms on the accuracy of the classical method are discussed. The inelastic deformation for the material which the second algebraic equation can not describe due to the omission of unsteady terms is presented. The precondition for obtaining accurate results from the second algebraic equation is given out. Two criteria used to judge the effectiveness of the second algebraic equation are derived. To reduce the error related to the second algebraic equation of the classical method for some materials, two alternative identification methods are proposed. By combining the step of solving differential equation and genetic algorithm, the parameters in the Anand model originally identified by the second algebraic equation are determined in the process of the two proposed methods. The effectiveness of the two alternative methods is presented by identifying the material Anand parameters where the classical method can not be applied.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41333944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A phenomenon of the intermittence is a critical issue for electronic joints of components installed in such as a mobile carrier. In this study, a finite element analysis of DDR4 connector is utilized to assess the dynamic responses of terminal pairs embedded in the polymeric housing subjected to various mechanical shock conditions. Two approaches, respectively based on the contact normal force and relative displacement between the contacting terminal and the associated gold finger, are proposed to investigate the presence of intermittence. The intermittence of the critical terminal pair under various shock conditions along the normal and longitudinal direction of the terminal is found to be strongly related to the contact loss. Under the shock conditions along the transverse direction of the terminal, a threshold of the relative displacement between two reference points is set to effectively and accurately assess the occurrence of intermittence. The elastic/elastic-plastic multi-scale rough surface (MSRS) model adopted to directly estimate the contact resistance history of the terminal pair is further attempted. Relatively low contact resistance of the terminal pair under the condition denoting pass can be observed. On the other hand, a sudden rise of the contact resistance of the terminal pair under the condition referring to fail is demonstrated based on the MSRS model although dramatic underestimations of the contact resistance are given when the contact normal force is rather low.
{"title":"Experimental and Numerical Investigations of Intermittence for Electronic Connectors Subjected to Mechanical Shocks","authors":"T. Huang, K. Liao","doi":"10.1115/1.4054822","DOIUrl":"https://doi.org/10.1115/1.4054822","url":null,"abstract":"\u0000 A phenomenon of the intermittence is a critical issue for electronic joints of components installed in such as a mobile carrier. In this study, a finite element analysis of DDR4 connector is utilized to assess the dynamic responses of terminal pairs embedded in the polymeric housing subjected to various mechanical shock conditions. Two approaches, respectively based on the contact normal force and relative displacement between the contacting terminal and the associated gold finger, are proposed to investigate the presence of intermittence. The intermittence of the critical terminal pair under various shock conditions along the normal and longitudinal direction of the terminal is found to be strongly related to the contact loss. Under the shock conditions along the transverse direction of the terminal, a threshold of the relative displacement between two reference points is set to effectively and accurately assess the occurrence of intermittence. The elastic/elastic-plastic multi-scale rough surface (MSRS) model adopted to directly estimate the contact resistance history of the terminal pair is further attempted. Relatively low contact resistance of the terminal pair under the condition denoting pass can be observed. On the other hand, a sudden rise of the contact resistance of the terminal pair under the condition referring to fail is demonstrated based on the MSRS model although dramatic underestimations of the contact resistance are given when the contact normal force is rather low.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44540736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Structural components such as printed circuit boards (PCBs) are critical in the thermomechanical reliability assessment of electronic packages. Previous studies have shown that geometric parameters such as thickness and mechanical properties like elastic modulus of PCBs have direct influence on the reliability of electronic packages. Elastic material properties of PCBs are commonly characterized using equipment such as tensile testers and used in computational studies. However, in certain applications viscoelastic material properties are important. Viscoelastic influence on materials is evident when one exceeds the glass transition temperature of materials. Operating conditions or manufacturing conditions such as lamination and soldering may expose components to temperatures that exceed the glass transition temperatures. Knowing the viscoelastic behavior of the different components of electronic packages is important in order to perform accurate reliability assessment and design components such as printed circuit boards (PCBs) that will remain dimensionally stable after the manufacturing process. Previous researchers have used creep and stress relaxation test data to obtain the Prony series terms that represent the viscoelastic behavior and perform analysis. Others have used dynamic mechanical analysis in order to obtain frequency domain master curves that were converted to time domain before obtaining the Prony series terms. In this paper, nonlinear solvers were used on frequency domain master curve results from dynamic mechanical analysis to obtain Prony series terms and perform finite element analysis on the impact of adding viscoelastic properties when performing reliability assessment. The computational study results were used to perform comparative assessment to understand the impact of including viscoelastic behavior in reliability analysis under thermal cycling and drop testing for Wafer Level Chip Scale Packages.
{"title":"Viscoelastic Influence On the Board Level Assessment of Wafer Level Packages Under Drop Impact and Under Thermal Cycling","authors":"Abel Misrak, Rabin Bhandari, D. Agonafer","doi":"10.1115/1.4054784","DOIUrl":"https://doi.org/10.1115/1.4054784","url":null,"abstract":"\u0000 Structural components such as printed circuit boards (PCBs) are critical in the thermomechanical reliability assessment of electronic packages. Previous studies have shown that geometric parameters such as thickness and mechanical properties like elastic modulus of PCBs have direct influence on the reliability of electronic packages. Elastic material properties of PCBs are commonly characterized using equipment such as tensile testers and used in computational studies. However, in certain applications viscoelastic material properties are important. Viscoelastic influence on materials is evident when one exceeds the glass transition temperature of materials. Operating conditions or manufacturing conditions such as lamination and soldering may expose components to temperatures that exceed the glass transition temperatures. Knowing the viscoelastic behavior of the different components of electronic packages is important in order to perform accurate reliability assessment and design components such as printed circuit boards (PCBs) that will remain dimensionally stable after the manufacturing process. Previous researchers have used creep and stress relaxation test data to obtain the Prony series terms that represent the viscoelastic behavior and perform analysis. Others have used dynamic mechanical analysis in order to obtain frequency domain master curves that were converted to time domain before obtaining the Prony series terms. In this paper, nonlinear solvers were used on frequency domain master curve results from dynamic mechanical analysis to obtain Prony series terms and perform finite element analysis on the impact of adding viscoelastic properties when performing reliability assessment. The computational study results were used to perform comparative assessment to understand the impact of including viscoelastic behavior in reliability analysis under thermal cycling and drop testing for Wafer Level Chip Scale Packages.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63503681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Han-Ling Li, Yang Shen, Y. Hua, S. Sobolev, B. Cao
Exact assessment of self-heating is of great importance to the thermal management of electronic devices, especially when completely considering the cross-scale heat conduction process. The existing simulation methods are either based on convectional Fourier's law or limited to small system sizes, making it difficult to deal with non-continuum thermal transport efficiently. In this paper, a hybrid phonon Monte Carlo-diffusion method is adopted to predict device temperature in ballistic-diffusive regime. Heat conduction around the heat generation region and boundaries are simulated by phonon Monte Carlo (MC) method, while the other domain is by Fourier's law. The temperature of the hybrid method is higher than that of Fourier's law owing to phonon ballistic transport, and the calculation efficiency of the hybrid method is remarkably improved compared with phonon MC simulation. Furthermore, the simulation results indicate that the way of modeling self-heating has a remarkable impact on phonon transport. The junction temperature of the heat source (HS) scheme can be larger than that of the heat flux (HF) scheme, which is opposite to the result under Fourier's law. In the HS scheme, the enhanced phonon-boundary scattering counteracts the broadening of the heat source, leading to a stronger ballistic effect and higher temperatures. The conclusion is verified by a one-dimensional analytical model. This work has opened up an opportunity for the fast and extensive thermal simulations of cross-scale heat transfer in electronic devices and highlighted the influence of heating schemes.
{"title":"Hybrid Monte Carlo-Diffusion Studies of Modeling Self-Heating in Ballistic-Diffusive Regime for GaN HEMTs","authors":"Han-Ling Li, Yang Shen, Y. Hua, S. Sobolev, B. Cao","doi":"10.1115/1.4054698","DOIUrl":"https://doi.org/10.1115/1.4054698","url":null,"abstract":"\u0000 Exact assessment of self-heating is of great importance to the thermal management of electronic devices, especially when completely considering the cross-scale heat conduction process. The existing simulation methods are either based on convectional Fourier's law or limited to small system sizes, making it difficult to deal with non-continuum thermal transport efficiently. In this paper, a hybrid phonon Monte Carlo-diffusion method is adopted to predict device temperature in ballistic-diffusive regime. Heat conduction around the heat generation region and boundaries are simulated by phonon Monte Carlo (MC) method, while the other domain is by Fourier's law. The temperature of the hybrid method is higher than that of Fourier's law owing to phonon ballistic transport, and the calculation efficiency of the hybrid method is remarkably improved compared with phonon MC simulation. Furthermore, the simulation results indicate that the way of modeling self-heating has a remarkable impact on phonon transport. The junction temperature of the heat source (HS) scheme can be larger than that of the heat flux (HF) scheme, which is opposite to the result under Fourier's law. In the HS scheme, the enhanced phonon-boundary scattering counteracts the broadening of the heat source, leading to a stronger ballistic effect and higher temperatures. The conclusion is verified by a one-dimensional analytical model. This work has opened up an opportunity for the fast and extensive thermal simulations of cross-scale heat transfer in electronic devices and highlighted the influence of heating schemes.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63503673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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