Michael E. Deckard, D. Sharar, M. Fish, P. Shamberger
Phase change materials (PCMs) can provide thermal buffering to systems that experience transient heat loads, including electronics packaging. Placing the PCM in the primary path of heat rejection decreases the thermal resistance between the heat source and the PCM volume, but increases the total thermal resistance between the heat source and heat sink. In systems that operate in both steady-state and transient regimes, this introduces tradeoffs between cooling performance in these distinct regimes. Employing a conductive finite volume model, Parapower, we investigate those tradeoffs considering the impact of adding a layer of gallium (Ga), a low melting point metal, and a layer of copper (Cu) between a planar heat source and a convective boundary condition heatsink. We demonstrate: 1) side-by-side comparisons of latent (Ga) and sensible (Cu) heat storage layers must consider different layer thicknesses to account for the different thermal storage mechanisms, 2) for short periods of time, conditions exist in which a PCM outperforms a traditional heat sink for transient thermal buffering at an equivalent steady state temperature rise, and 3) under these conditions, the Ga layer is approximately an order of magnitude thinner than the equivalent Cu, leading to significant mass and volume savings.
{"title":"Phase Change Material Behavior in Finite Thickness Slabs Under a Step Response Heat","authors":"Michael E. Deckard, D. Sharar, M. Fish, P. Shamberger","doi":"10.1115/1.4054651","DOIUrl":"https://doi.org/10.1115/1.4054651","url":null,"abstract":"\u0000 Phase change materials (PCMs) can provide thermal buffering to systems that experience transient heat loads, including electronics packaging. Placing the PCM in the primary path of heat rejection decreases the thermal resistance between the heat source and the PCM volume, but increases the total thermal resistance between the heat source and heat sink. In systems that operate in both steady-state and transient regimes, this introduces tradeoffs between cooling performance in these distinct regimes. Employing a conductive finite volume model, Parapower, we investigate those tradeoffs considering the impact of adding a layer of gallium (Ga), a low melting point metal, and a layer of copper (Cu) between a planar heat source and a convective boundary condition heatsink. We demonstrate: 1) side-by-side comparisons of latent (Ga) and sensible (Cu) heat storage layers must consider different layer thicknesses to account for the different thermal storage mechanisms, 2) for short periods of time, conditions exist in which a PCM outperforms a traditional heat sink for transient thermal buffering at an equivalent steady state temperature rise, and 3) under these conditions, the Ga layer is approximately an order of magnitude thinner than the equivalent Cu, leading to significant mass and volume savings.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48332110","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}
Ahmad R. Gharaibeh, Yaman M. Manaserh, Mohammad I. Tradat, Firas Alshatnawi, Scott N. Schiffres, B. Sammakia
The increased power consumption and continued miniaturization of high-powered electronic components has presented many challenges to their thermal management. To improve the efficiency and reliability of these devices, the high amount of heat that they generate must be properly removed. In this paper, a three-dimensional numerical model has been developed and experimentally validated for several manifold heat sink designs. The goal was to enhance the heat sink's thermal performance while reducing the required pumping power by lowering the pressure drop across the heat sink. The considered designs were benchmarked to a commercially available heat sink in terms of their thermal and hydraulic performances. The proposed manifolds were designed to distribute fluid through alternating inlet and outlet branched internal channels. It was found that using the manifold design with 3 channels reduced the thermal resistance from 0.061 to 0.054 °C/W with a pressure drop reduction of 0.77 kPa from the commercial cold plate. A geometric parametric study was performed to investigate the effect of the manifold's internal channels width on the thermohydraulic performance of the proposed designs. It was found that the thermal resistance decreased as the manifold's channel width decreased, up until a certain width value, below which the thermal resistance started to increase while maintaining low pressure drop values. Where the thermal resistance significantly decreased in the 7 channels design by 16.4% and maintained a lower pressure drop value below 0.6 kpa.
{"title":"Using a Multi-Inlet/Outlet Manifold to Improve Heat Transfer and Flow Distribution of a Pin Fin Heat Sink","authors":"Ahmad R. Gharaibeh, Yaman M. Manaserh, Mohammad I. Tradat, Firas Alshatnawi, Scott N. Schiffres, B. Sammakia","doi":"10.1115/1.4054461","DOIUrl":"https://doi.org/10.1115/1.4054461","url":null,"abstract":"\u0000 The increased power consumption and continued miniaturization of high-powered electronic components has presented many challenges to their thermal management. To improve the efficiency and reliability of these devices, the high amount of heat that they generate must be properly removed. In this paper, a three-dimensional numerical model has been developed and experimentally validated for several manifold heat sink designs. The goal was to enhance the heat sink's thermal performance while reducing the required pumping power by lowering the pressure drop across the heat sink. The considered designs were benchmarked to a commercially available heat sink in terms of their thermal and hydraulic performances. The proposed manifolds were designed to distribute fluid through alternating inlet and outlet branched internal channels. It was found that using the manifold design with 3 channels reduced the thermal resistance from 0.061 to 0.054 °C/W with a pressure drop reduction of 0.77 kPa from the commercial cold plate. A geometric parametric study was performed to investigate the effect of the manifold's internal channels width on the thermohydraulic performance of the proposed designs. It was found that the thermal resistance decreased as the manifold's channel width decreased, up until a certain width value, below which the thermal resistance started to increase while maintaining low pressure drop values. Where the thermal resistance significantly decreased in the 7 channels design by 16.4% and maintained a lower pressure drop value below 0.6 kpa.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45569302","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}
Aiming at the failure problem of aerospace electronic product at the complex space environment, the electro-thermal coupling method has been used to analyze the reliability of the 10 channels independently adjustable voltage conversion SIP module based on integrated forming package, which has supply the voltage to the remote sensing camera detector. Firstly, the electromagnetic model and thermal model have been made based on the SIP module; secondly, the electro-thermal coupling simulation at different temperature of three working condition at normal environment have been made, and the maximum temperature of the SIP has been calculated; then, the temperature of the SIP has been also calculated under vacuum and 45 ? to analyzing maximum temperatures in the space work environment; at last, some test have been made of the SIP product. Compared with the measured results, the electro-thermal coupling method has much more accurate than traditional thermal method. At normal environment, the temperature relative error of which is 2.8%. At vacuum and 45 ? environment, the temperature relative error of which is 9%?This method ensured the performance and accurate of the design of the SIP, and which has verified the reliability of aerospace SIP module at early stage.
{"title":"Electro-Thermal Analysis of System in Package for Aerospace Application","authors":"Hao-hang Su, Shuai Fu, Su Li, J. Bian","doi":"10.1115/1.4054462","DOIUrl":"https://doi.org/10.1115/1.4054462","url":null,"abstract":"\u0000 Aiming at the failure problem of aerospace electronic product at the complex space environment, the electro-thermal coupling method has been used to analyze the reliability of the 10 channels independently adjustable voltage conversion SIP module based on integrated forming package, which has supply the voltage to the remote sensing camera detector. Firstly, the electromagnetic model and thermal model have been made based on the SIP module; secondly, the electro-thermal coupling simulation at different temperature of three working condition at normal environment have been made, and the maximum temperature of the SIP has been calculated; then, the temperature of the SIP has been also calculated under vacuum and 45 ? to analyzing maximum temperatures in the space work environment; at last, some test have been made of the SIP product. Compared with the measured results, the electro-thermal coupling method has much more accurate than traditional thermal method. At normal environment, the temperature relative error of which is 2.8%. At vacuum and 45 ? environment, the temperature relative error of which is 9%?This method ensured the performance and accurate of the design of the SIP, and which has verified the reliability of aerospace SIP module at early stage.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41539662","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}
Sara K. Lyons, Aditya Chandramohan, J. Weibel, S. Garimella
For microelectronic components and systems, reliability under thermomechanical stress is of critical importance and relies on accurate mapping of surface hotspots and temperature gradients. One method of non-invasively acquiring this data is through infrared (IR) thermography. However, IR thermography is often limited by the typically low resolution of such cameras. Additionally, the surface finish preparations required to infer physical deformation using digital image correlation (DIC) interferes with the ability to measure the temperature with IR thermography, which prefers a uniform high emissivity. This work introduces a one-shot technique for the simultaneous measurement of surface temperature and deformation using multiframe super-resolution-enhanced IR imaging combined with digital image correlation (DIC) analysis. Multiframe super-resolution processing uses several sub-pixel shifted images to extract a single higher-resolution image. Measurement of physical deformation is incorporated using a test sample with a black background and low-emissivity speckle features. Through processing and filtering, data from the black surface regions used for surface temperature mapping are separated from the speckle features used to track deformation with DIC. This method allows DIC to be performed on the IR images, yielding a deformation field consistent with applied tensioning. While both the low- and super-resolution data sets can be successfully processed with DIC, super-resolution helps reduce noise in the extracted deformation fields. As for temperature measurement, using super-resolution is shown to allow for better removal of the speckle features, as quantified by a lower mean deviation from the spatial moving average.
{"title":"Simultaneous Measurement of Temperature and Strain in Electronic Packages Using Multiframe Super-Resolution Infrared Thermography and Digital Image Correlation","authors":"Sara K. Lyons, Aditya Chandramohan, J. Weibel, S. Garimella","doi":"10.1115/1.4054263","DOIUrl":"https://doi.org/10.1115/1.4054263","url":null,"abstract":"\u0000 For microelectronic components and systems, reliability under thermomechanical stress is of critical importance and relies on accurate mapping of surface hotspots and temperature gradients. One method of non-invasively acquiring this data is through infrared (IR) thermography. However, IR thermography is often limited by the typically low resolution of such cameras. Additionally, the surface finish preparations required to infer physical deformation using digital image correlation (DIC) interferes with the ability to measure the temperature with IR thermography, which prefers a uniform high emissivity. This work introduces a one-shot technique for the simultaneous measurement of surface temperature and deformation using multiframe super-resolution-enhanced IR imaging combined with digital image correlation (DIC) analysis. Multiframe super-resolution processing uses several sub-pixel shifted images to extract a single higher-resolution image. Measurement of physical deformation is incorporated using a test sample with a black background and low-emissivity speckle features. Through processing and filtering, data from the black surface regions used for surface temperature mapping are separated from the speckle features used to track deformation with DIC. This method allows DIC to be performed on the IR images, yielding a deformation field consistent with applied tensioning. While both the low- and super-resolution data sets can be successfully processed with DIC, super-resolution helps reduce noise in the extracted deformation fields. As for temperature measurement, using super-resolution is shown to allow for better removal of the speckle features, as quantified by a lower mean deviation from the spatial moving average.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43037678","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}
Pool boiling heat transfer offers high-performance cooling opportunities for thermal problems of electronics limited with high heat fluxes. Therefore, many researchers have been extensively studying over the last six decades. This paper presents a critical literature review of various parametric effects on pool boiling heat transfer and CHF such as pressure, subcooling, surface topography, surface orientation, working fluid, and combined effects. To achieve an optimal heat removal solution for a particular problem, each of these parameters must be understood. The governing mechanisms are discussed separately, and various options related to the selection of appropriate working fluids are highlighted. A broad summary of correlations developed until now for predicting critical heat flux (CHF) is presented with their ranges of validity. While proposed correlations for predicting CHF has been quite promising, they still have a considerable uncertainty (±25%). Finally, a correlation proposed by Professor Avram Bar-Cohen and his team (TME correlation) is compared with the experimental data set published in previous studies. It shows that the uncertainty band can be further narrowed down to ±12.5% for dielectric liquids by using TME correlation. Furthermore, this correlation has been enhanced to predict CHF values underwater above 50 W/cm2 by applying a genetic algorithm, and new perspectives for possible future research activities are proposed.
{"title":"Parametric Effects On Pool Boiling Heat Transfer and Critical Heat Flux: A Critical Review","authors":"Tolga Emir, H. Ourabi, M. Budakli, M. Arik","doi":"10.1115/1.4054184","DOIUrl":"https://doi.org/10.1115/1.4054184","url":null,"abstract":"\u0000 Pool boiling heat transfer offers high-performance cooling opportunities for thermal problems of electronics limited with high heat fluxes. Therefore, many researchers have been extensively studying over the last six decades. This paper presents a critical literature review of various parametric effects on pool boiling heat transfer and CHF such as pressure, subcooling, surface topography, surface orientation, working fluid, and combined effects. To achieve an optimal heat removal solution for a particular problem, each of these parameters must be understood. The governing mechanisms are discussed separately, and various options related to the selection of appropriate working fluids are highlighted. A broad summary of correlations developed until now for predicting critical heat flux (CHF) is presented with their ranges of validity. While proposed correlations for predicting CHF has been quite promising, they still have a considerable uncertainty (±25%). Finally, a correlation proposed by Professor Avram Bar-Cohen and his team (TME correlation) is compared with the experimental data set published in previous studies. It shows that the uncertainty band can be further narrowed down to ±12.5% for dielectric liquids by using TME correlation. Furthermore, this correlation has been enhanced to predict CHF values underwater above 50 W/cm2 by applying a genetic algorithm, and new perspectives for possible future research activities are proposed.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47520224","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}
Tak-Wook Kim, Jaemin Kim, H. Yun, Jong-Sung Lee, Jae-Hak Lee, Song Jun-Yeob, Young‐Chang Joo, Won-Jun Lee, Byoung-Joon Kim
Although the reliability of flexible electronics during bending deformation is of great interest nowadays, the mechanical reliability that has mainly been investigated is of single electronic components or simple devices, such as metal interconnect, transparent conductive electrode, or thin-film devices, rather than that of the real package sample having complex structure and various materials. This study systematically investigated the mechanical reliability of flexible Si package sample consisting of Si die, polymer bump, and polymer substrate, by using individual resistance monitoring of the metal line, bump array, and total interconnect. For the bending test, the sample consisting of only Si die and polymer substrate shows abrupt electrical resistance increase below a bending radius of 3 mm, due to cracking of the Si die. For the bending fatigue test, the electrical resistance increases after 2,000 cycles in 5 mm bending radius, due to fatigue failure of the metal line and bump array. Both the maximum bendability and fatigue lifetime can be significantly improved by covering with the molding layer. Finite element method simulation is conducted to analyze the mechanical stress distribution of the flexible package with and without molding layer during bending deformation. This study based on experimental results and simulation analysis can provide helpful guidelines for the design of highly reliable flexible packages.
{"title":"Electrical Reliability of Flexible Silicon Package Integrated On Polymer Substrate During Repeated Bending Deformations","authors":"Tak-Wook Kim, Jaemin Kim, H. Yun, Jong-Sung Lee, Jae-Hak Lee, Song Jun-Yeob, Young‐Chang Joo, Won-Jun Lee, Byoung-Joon Kim","doi":"10.1115/1.4054183","DOIUrl":"https://doi.org/10.1115/1.4054183","url":null,"abstract":"\u0000 Although the reliability of flexible electronics during bending deformation is of great interest nowadays, the mechanical reliability that has mainly been investigated is of single electronic components or simple devices, such as metal interconnect, transparent conductive electrode, or thin-film devices, rather than that of the real package sample having complex structure and various materials. This study systematically investigated the mechanical reliability of flexible Si package sample consisting of Si die, polymer bump, and polymer substrate, by using individual resistance monitoring of the metal line, bump array, and total interconnect. For the bending test, the sample consisting of only Si die and polymer substrate shows abrupt electrical resistance increase below a bending radius of 3 mm, due to cracking of the Si die. For the bending fatigue test, the electrical resistance increases after 2,000 cycles in 5 mm bending radius, due to fatigue failure of the metal line and bump array. Both the maximum bendability and fatigue lifetime can be significantly improved by covering with the molding layer. Finite element method simulation is conducted to analyze the mechanical stress distribution of the flexible package with and without molding layer during bending deformation. This study based on experimental results and simulation analysis can provide helpful guidelines for the design of highly reliable flexible packages.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41970186","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 transition of additive printed electronics into high-volume production requires process consistency to allow quality control of the manufactured product. Process recipes are needed for multilayer substrates with z-axis interconnects in order to enable complex systems. In this paper, process recipes have been developed through fundamental studies of the interactions between the process parameters and the mechanical-electrical performance achieved for multilayer substrates. The study reported in this paper focuses on printed vias also known as donut vias. Aerosol jet process parameters studied include carrier mass flow rate, sheath mass flow rate, exhaust mass flow rate, print speed, number of passes, sintering time and temperature, UV-intensity for UV-cure, and standoff height. The electrical performance has been quantified through the measurements of resistance. The mechanical performance has been quantified through measurement of shear load-to-failure. The effect of sequential build-up on the mechanical-electrical properties vs process parameters have been quantified for up to 8-layers designs. The performance of 5-layer and 8-layer additively printed substrate designs and effect of multiple vias has been compared to assess process consistency.
{"title":"Multilayer Conductive Metallization with Offset Vias Using Aerosol Jet Technology","authors":"P. Lall, Kartik Goyal, Scott Miller","doi":"10.1115/1.4054131","DOIUrl":"https://doi.org/10.1115/1.4054131","url":null,"abstract":"\u0000 The transition of additive printed electronics into high-volume production requires process consistency to allow quality control of the manufactured product. Process recipes are needed for multilayer substrates with z-axis interconnects in order to enable complex systems. In this paper, process recipes have been developed through fundamental studies of the interactions between the process parameters and the mechanical-electrical performance achieved for multilayer substrates. The study reported in this paper focuses on printed vias also known as donut vias. Aerosol jet process parameters studied include carrier mass flow rate, sheath mass flow rate, exhaust mass flow rate, print speed, number of passes, sintering time and temperature, UV-intensity for UV-cure, and standoff height. The electrical performance has been quantified through the measurements of resistance. The mechanical performance has been quantified through measurement of shear load-to-failure. The effect of sequential build-up on the mechanical-electrical properties vs process parameters have been quantified for up to 8-layers designs. The performance of 5-layer and 8-layer additively printed substrate designs and effect of multiple vias has been compared to assess process consistency.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41325036","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}
Z. Bachok, M. A. Abas, Muhammad Zaim Hanif Nazarudin, Saifulmajdy A. Zahiri, Mohamad Fikri Mohd Sharif, F. Che Ani
Laser soldering is becoming more popular for soldering pin through-hole (PTH) components onto printed circuit boards (PCBs). Solder volume influences soldering joint reliability. However, it is difficult to accurately measure the effect of solder volume during the laser soldering process. The finite volume method (FVM) is used to simulate the molten solder flow in laser soldering to connect the through-hole capacitor onto the PCB in ANSYS Fluent software. The simulation results reveal the effects of different SAC305 solder volumes on joining quality in terms of fillet shape formation, pressure, and velocity. The preferred solder volume is 1.517 mm3 with a filling time of 1.7 seconds, a temperature of 642K, a hole diameter of 1.0 mm, a lead diameter of 0.5 mm and a PCB thickness of 1.20 mm, produces a fillet shape similar to a real sample of PTH laser soldering joint from the industry. This ideal volume was chosen with a suitable pressure and velocity to create a nice concave fillet shape and minimize voids during soldering. The pressure and velocity increase when the solder volume increases causing solidified solder to melt. The discrepancy between numerical and experimental values of fillet height is comparable, which inferred that the numerical model was well-validated. The good consistency between both results prove that the finite volume model will effectively predict the optimum solder volume. This opens up new opportunities for the optimization of the laser soldering parameters in the application of electronic manufacturing.
{"title":"Effect of Different Solder Volumes On the Laser Soldering Process: Numerical and Experimental Investigation","authors":"Z. Bachok, M. A. Abas, Muhammad Zaim Hanif Nazarudin, Saifulmajdy A. Zahiri, Mohamad Fikri Mohd Sharif, F. Che Ani","doi":"10.1115/1.4054132","DOIUrl":"https://doi.org/10.1115/1.4054132","url":null,"abstract":"\u0000 Laser soldering is becoming more popular for soldering pin through-hole (PTH) components onto printed circuit boards (PCBs). Solder volume influences soldering joint reliability. However, it is difficult to accurately measure the effect of solder volume during the laser soldering process. The finite volume method (FVM) is used to simulate the molten solder flow in laser soldering to connect the through-hole capacitor onto the PCB in ANSYS Fluent software. The simulation results reveal the effects of different SAC305 solder volumes on joining quality in terms of fillet shape formation, pressure, and velocity. The preferred solder volume is 1.517 mm3 with a filling time of 1.7 seconds, a temperature of 642K, a hole diameter of 1.0 mm, a lead diameter of 0.5 mm and a PCB thickness of 1.20 mm, produces a fillet shape similar to a real sample of PTH laser soldering joint from the industry. This ideal volume was chosen with a suitable pressure and velocity to create a nice concave fillet shape and minimize voids during soldering. The pressure and velocity increase when the solder volume increases causing solidified solder to melt. The discrepancy between numerical and experimental values of fillet height is comparable, which inferred that the numerical model was well-validated. The good consistency between both results prove that the finite volume model will effectively predict the optimum solder volume. This opens up new opportunities for the optimization of the laser soldering parameters in the application of electronic manufacturing.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41347952","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}
Low-silver solders are increasingly being used because silver improves the tensile strength. In this study, the variation in fracture behavior with silver content in lead-free solder joints were studied using double cantilever beam specimens. Fracture tests were done with solder joints made with Sn-0.7Cu, SACX0307, and SAC305 solder materials. The critical energy release rate for crack-initiation (Gci) of the joint was correlated with the plastic zone just ahead of the pre-crack tip, intermetallic compound layer thickness, energy dispersive spectroscopy analysis, and scanning electron microscopy based fractography study. The Gci for Sn-0.7Cu solder joint was observed to be significantly higher than the other two solder joints. The fractography study revealed that the failure was ductile for Sn-0.7Cu and a mix of ductile and brittle for the other two solder joints. The extent of the plastic zone ahead of the crack tip, obtained from finite element modeling, was found to be significantly larger and the intermetallic compound layer was relatively thinner for Sn-0.7Cu solder joint compared to the other two solder joints. The ductile failure, significantly larger plastic zone size and thinner intermetallic compound layer resulted in significantly higher Gci for Sn-0.7Cu solder joint.
{"title":"Fracture Behavior and Reliability of Low-Silver Lead-free Solder Joints","authors":"Ved Prakash Sharma, N. Datla","doi":"10.1115/1.4054096","DOIUrl":"https://doi.org/10.1115/1.4054096","url":null,"abstract":"\u0000 Low-silver solders are increasingly being used because silver improves the tensile strength. In this study, the variation in fracture behavior with silver content in lead-free solder joints were studied using double cantilever beam specimens. Fracture tests were done with solder joints made with Sn-0.7Cu, SACX0307, and SAC305 solder materials. The critical energy release rate for crack-initiation (Gci) of the joint was correlated with the plastic zone just ahead of the pre-crack tip, intermetallic compound layer thickness, energy dispersive spectroscopy analysis, and scanning electron microscopy based fractography study. The Gci for Sn-0.7Cu solder joint was observed to be significantly higher than the other two solder joints. The fractography study revealed that the failure was ductile for Sn-0.7Cu and a mix of ductile and brittle for the other two solder joints. The extent of the plastic zone ahead of the crack tip, obtained from finite element modeling, was found to be significantly larger and the intermetallic compound layer was relatively thinner for Sn-0.7Cu solder joint compared to the other two solder joints. The ductile failure, significantly larger plastic zone size and thinner intermetallic compound layer resulted in significantly higher Gci for Sn-0.7Cu solder joint.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49522639","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}
Shiva Farzinazar, Z. Ren, Jung‐Youn Lim, Jae Choon Kim, Jaeho Lee
Heterogeneous and complex electronic packages may require unique thermo-mechanical structures to provide optimal heat guiding. In particular, when a heat source and a heat sink are not aligned, conventional thermal management methods providing uniform heat dissipation may not be appropriate. Here we present a topology optimization method to find thermally conductive and mechanically stable structures for optimal heat guiding under various heat source-sink arrangements. To exploit the capabilities, we consider complex heat guiding scenarios and 3D serpentine structures to carry the heat with corner angles ranging from 30° to 90°. While the thermal objective function is defined to minimize the temperature gradient, the mechanical objective function is defined to maximize the stiffness with a volume constraint. Our simulations show that the optimized structures can have a thermal resistance of less than 32% and stiffness greater than 43% compared to reference structures with no topology optimization at an identical volume fraction. The significant difference in thermal resistance is attributed to a thermally dead volume near the sharp corners. As a proof-of-concept experiment, we have created 3D heat guiding structures using a selective laser melting technique and characterized their thermal properties using an infrared thermography technique. The experiment shows the thermal resistance of the thermally optimized structure is 29% less than that of the reference structure. These results present unique capabilities of topology optimization and 3D manufacturing in enabling optimal heat guiding for heterogeneous systems and advancing the state-of-the-art in electronics packaging.
{"title":"Thermo-Mechanical Topology Optimization of 3D Heat Guiding Structures for Electronics Packaging","authors":"Shiva Farzinazar, Z. Ren, Jung‐Youn Lim, Jae Choon Kim, Jaeho Lee","doi":"10.1115/1.4053948","DOIUrl":"https://doi.org/10.1115/1.4053948","url":null,"abstract":"\u0000 Heterogeneous and complex electronic packages may require unique thermo-mechanical structures to provide optimal heat guiding. In particular, when a heat source and a heat sink are not aligned, conventional thermal management methods providing uniform heat dissipation may not be appropriate. Here we present a topology optimization method to find thermally conductive and mechanically stable structures for optimal heat guiding under various heat source-sink arrangements. To exploit the capabilities, we consider complex heat guiding scenarios and 3D serpentine structures to carry the heat with corner angles ranging from 30° to 90°. While the thermal objective function is defined to minimize the temperature gradient, the mechanical objective function is defined to maximize the stiffness with a volume constraint. Our simulations show that the optimized structures can have a thermal resistance of less than 32% and stiffness greater than 43% compared to reference structures with no topology optimization at an identical volume fraction. The significant difference in thermal resistance is attributed to a thermally dead volume near the sharp corners. As a proof-of-concept experiment, we have created 3D heat guiding structures using a selective laser melting technique and characterized their thermal properties using an infrared thermography technique. The experiment shows the thermal resistance of the thermally optimized structure is 29% less than that of the reference structure. These results present unique capabilities of topology optimization and 3D manufacturing in enabling optimal heat guiding for heterogeneous systems and advancing the state-of-the-art in electronics packaging.","PeriodicalId":15663,"journal":{"name":"Journal of Electronic Packaging","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48768140","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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