Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103143
F. Kraemer, C. Pauly, F. Muecklich, S. Wiese
New bonding techniques are required in order to overcome the problems caused by the necessary interconnection of big and thin silicon chips with organic interposers. A local heat source at the bonding interface would be beneficial in order to reduce the adverse thermal stress on the emerging assemblies. The required local heating can be achieved by reactive foils, which are stacks of thin metal layers that intermix after an ignition and supply thermal energy during this reaction. This paper summarises the results of a thermal transient FEM analysis, which checks the applicability of reactive foils as local heat source for the soldering of flip chip interconnections. This thermal analysis applies an artificial test structure with the interconnection dimensions of a flip chip assembly. The surrounding silicon chip and substrate have much larger dimensions in order to act as a heat sink with a large thermal mass. The interconnections are arranged in such a way that thermal interactions between adjacent interconnections can be analysed. The thermal energy of the reactive foil is induced sequentially to the assembly at the interface between substrate pad and solder joint. The simulation results show a localised influence of the thermal energy to the assembly. The heat distributes over the substrate pads and the adjacent solder volume. Increased temperatures are barely visible in the substrate and the silicon chip. The substrate acts as thermal isolator and the heat conduction through the solder ball is much slower than the reaction speed of the foil. Thus, even the small pitch between the flip chip interconnections causes a sufficient thermal isolation during the rapid process. The temperature increase at the silicon is just less than 10K. However the thermal isolation enables the conversion of the limited thermal energy into high temperatures. The temperatures on top of the copper pad are sufficiently high to melt the adjacent solder. Furthermore the temperatures are high enough to continue the self-propagating reaction of the foil. The major influence on the resulting maximum temperature is the energy input of the foil, which is defined by the type of reactive system and its thickness.
{"title":"Simulation of a flip chip bonding technique using reactive foils","authors":"F. Kraemer, C. Pauly, F. Muecklich, S. Wiese","doi":"10.1109/EUROSIME.2015.7103143","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103143","url":null,"abstract":"New bonding techniques are required in order to overcome the problems caused by the necessary interconnection of big and thin silicon chips with organic interposers. A local heat source at the bonding interface would be beneficial in order to reduce the adverse thermal stress on the emerging assemblies. The required local heating can be achieved by reactive foils, which are stacks of thin metal layers that intermix after an ignition and supply thermal energy during this reaction. This paper summarises the results of a thermal transient FEM analysis, which checks the applicability of reactive foils as local heat source for the soldering of flip chip interconnections. This thermal analysis applies an artificial test structure with the interconnection dimensions of a flip chip assembly. The surrounding silicon chip and substrate have much larger dimensions in order to act as a heat sink with a large thermal mass. The interconnections are arranged in such a way that thermal interactions between adjacent interconnections can be analysed. The thermal energy of the reactive foil is induced sequentially to the assembly at the interface between substrate pad and solder joint. The simulation results show a localised influence of the thermal energy to the assembly. The heat distributes over the substrate pads and the adjacent solder volume. Increased temperatures are barely visible in the substrate and the silicon chip. The substrate acts as thermal isolator and the heat conduction through the solder ball is much slower than the reaction speed of the foil. Thus, even the small pitch between the flip chip interconnections causes a sufficient thermal isolation during the rapid process. The temperature increase at the silicon is just less than 10K. However the thermal isolation enables the conversion of the limited thermal energy into high temperatures. The temperatures on top of the copper pad are sufficiently high to melt the adjacent solder. Furthermore the temperatures are high enough to continue the self-propagating reaction of the foil. The major influence on the resulting maximum temperature is the energy input of the foil, which is defined by the type of reactive system and its thickness.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114609796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103078
B. Ozturk, P. Lou, P. Gromala, C. Silber, K. Jansen, L. Ernst
Thermoset-based adhesives are used as thermal and electrical interfaces. In automotive applications, they are required to have excellent adhesion since delamination may precipitate other electrical, thermal or mechanical failure mechanisms. A vast amount of literature is available on the investigation of molding compounds and various material interfaces. However, only very few studies focus on delamination of adhesive interfaces. The reason is that apparently it was not possible to initiate an interface crack in a delamination sample. In various attempts, random cracking in the adhesive was obtained instead. Yet interface cracks are found in real products and really form a reliability issue. But so far the absence of adequate interface strength data makes it hardly possible to design for reliability of products with adhesive interfaces. The present paper solves the above problem. We succeeded to get an interface delamination between the adhesive and two different materials (e.g. Low temperature cofrred ceramic (L TCC) and alloy 42). The specimens are made by identical fabrications processes as during the fabrication of the electronic control unit under study. The interface to be investigated is preconditioned for delamination initiation, by adding a single step to the fabrication process, thus enabling the investigation of different interfaces that have the same processing conditions as the real product. The presented specimen preparation method and the testing methodology can be used for determination of critical adhesion properties of different interfaces (including brittle materials like L TCC) in electronic control units. Specimens are investigated by delamination experiments near Mode-I loading conditions at room temperature. The obtained interface data is interpreted via image processing and finite element modeling of the J-integral method. In particular, cohesive zone modeling is used to validate the critical energy release rates for different interfaces.
{"title":"Characterization and simulation of LTCC/adhesive and alloy 42/adhesive interface strength for automotive applications","authors":"B. Ozturk, P. Lou, P. Gromala, C. Silber, K. Jansen, L. Ernst","doi":"10.1109/EUROSIME.2015.7103078","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103078","url":null,"abstract":"Thermoset-based adhesives are used as thermal and electrical interfaces. In automotive applications, they are required to have excellent adhesion since delamination may precipitate other electrical, thermal or mechanical failure mechanisms. A vast amount of literature is available on the investigation of molding compounds and various material interfaces. However, only very few studies focus on delamination of adhesive interfaces. The reason is that apparently it was not possible to initiate an interface crack in a delamination sample. In various attempts, random cracking in the adhesive was obtained instead. Yet interface cracks are found in real products and really form a reliability issue. But so far the absence of adequate interface strength data makes it hardly possible to design for reliability of products with adhesive interfaces. The present paper solves the above problem. We succeeded to get an interface delamination between the adhesive and two different materials (e.g. Low temperature cofrred ceramic (L TCC) and alloy 42). The specimens are made by identical fabrications processes as during the fabrication of the electronic control unit under study. The interface to be investigated is preconditioned for delamination initiation, by adding a single step to the fabrication process, thus enabling the investigation of different interfaces that have the same processing conditions as the real product. The presented specimen preparation method and the testing methodology can be used for determination of critical adhesion properties of different interfaces (including brittle materials like L TCC) in electronic control units. Specimens are investigated by delamination experiments near Mode-I loading conditions at room temperature. The obtained interface data is interpreted via image processing and finite element modeling of the J-integral method. In particular, cohesive zone modeling is used to validate the critical energy release rates for different interfaces.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134418279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103148
C. C. Jung, C. Silber, J. Scheible
When a bonding wire becomes too hot, it fuses and fails. The ohmic heat that is generated in the wire can be partially dissipated to a mold package. For this cooling effect the thermal contact between wire and package is an important parameter. Because this parameter can degrade over lifetime, the fusing of a bonding wire can also occur as a long-term effect. Another important factor is the thermal power generated in the vicinity of the bond pads. Nowadays, the reliability of bond wires relies on robust dimensioning based on estimations. Smaller package sizes increase the need for better predictive methods.The Bond Calculator, a new thermo-electrical simulation tool, is able to predict the temperature profiles along bond wires of arbitrary dimensions in dependence on the applied arbitrary transient current profile, the mold surrounding the wire, and the thermal contact between wire and mold. In this paper we closely investigated the spatial temperature profiles along different bond wires in air in order to make a first step towards the experimental verification of the simulation model. We are using infrared microscopy in order to measure the thermal radiation generated along the bond wire. This is easier to perform quantitatively in air than in the mold package, because of the non-negligible absorbance of the mold material in the infrared wavelength region.
{"title":"Temperature profiles along bonding wires, revealed by the bond calculator, a new thermo-electrical simulation tool","authors":"C. C. Jung, C. Silber, J. Scheible","doi":"10.1109/EUROSIME.2015.7103148","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103148","url":null,"abstract":"When a bonding wire becomes too hot, it fuses and fails. The ohmic heat that is generated in the wire can be partially dissipated to a mold package. For this cooling effect the thermal contact between wire and package is an important parameter. Because this parameter can degrade over lifetime, the fusing of a bonding wire can also occur as a long-term effect. Another important factor is the thermal power generated in the vicinity of the bond pads. Nowadays, the reliability of bond wires relies on robust dimensioning based on estimations. Smaller package sizes increase the need for better predictive methods.The Bond Calculator, a new thermo-electrical simulation tool, is able to predict the temperature profiles along bond wires of arbitrary dimensions in dependence on the applied arbitrary transient current profile, the mold surrounding the wire, and the thermal contact between wire and mold. In this paper we closely investigated the spatial temperature profiles along different bond wires in air in order to make a first step towards the experimental verification of the simulation model. We are using infrared microscopy in order to measure the thermal radiation generated along the bond wire. This is easier to perform quantitatively in air than in the mold package, because of the non-negligible absorbance of the mold material in the infrared wavelength region.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133887533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103139
R. Dudek, R. Doring, S. Rzepka, C. Ehrhardt, M. Gunther, M. Haag
New demands on the thermo-mechanical design of sintered silver interconnections emerge. Development of this inter-connection technology and both experimental and theoretical studies on their reliability were subjects of the project “PROPOWER”. The focus of this paper is on theoretical analysis of thermo-mechanical reliability risks of a project demonstrator, an insulated-gate bipolar transistor (IGBT) module, subjected to power cycling loadings. Coupled electro-thermal-mechanical analyses have been carried out using the finite element method (FEM). Introduction of a new interconnect material means at the same time introduction of a new constitutive behavior and new failure modes. As the material stiffness increases, the decoupling effect of compliant solder layers reduces and intrinsic mechanical stresses increase in the whole power stack. This leads on one hand to less low cycle fatigue in the interconnect, as plastic dissipation is reduced, but on the other hand to higher failure risks like brittle cracking and sub-critical crack growth. However, if early brittle failure can be avoided by appropriate designs, the new interconnection technology allows an increase in fatigue reliability of several hundred percent. Based on the complex theoretical framework simulation results are validated by testing in order to achieve trustworthy thermo-mechanical reliability predictions. Failures like chip metallization damage and the different damage mechanisms of the die bond if either solder or sinter silver is used are related to the different stress situations in the module.
{"title":"Electro-thermo-mechanical analyses on silver sintered IGBT-module reliability in power cycling","authors":"R. Dudek, R. Doring, S. Rzepka, C. Ehrhardt, M. Gunther, M. Haag","doi":"10.1109/EUROSIME.2015.7103139","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103139","url":null,"abstract":"New demands on the thermo-mechanical design of sintered silver interconnections emerge. Development of this inter-connection technology and both experimental and theoretical studies on their reliability were subjects of the project “PROPOWER”. The focus of this paper is on theoretical analysis of thermo-mechanical reliability risks of a project demonstrator, an insulated-gate bipolar transistor (IGBT) module, subjected to power cycling loadings. Coupled electro-thermal-mechanical analyses have been carried out using the finite element method (FEM). Introduction of a new interconnect material means at the same time introduction of a new constitutive behavior and new failure modes. As the material stiffness increases, the decoupling effect of compliant solder layers reduces and intrinsic mechanical stresses increase in the whole power stack. This leads on one hand to less low cycle fatigue in the interconnect, as plastic dissipation is reduced, but on the other hand to higher failure risks like brittle cracking and sub-critical crack growth. However, if early brittle failure can be avoided by appropriate designs, the new interconnection technology allows an increase in fatigue reliability of several hundred percent. Based on the complex theoretical framework simulation results are validated by testing in order to achieve trustworthy thermo-mechanical reliability predictions. Failures like chip metallization damage and the different damage mechanisms of the die bond if either solder or sinter silver is used are related to the different stress situations in the module.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"338 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134158771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103130
Martin Lederer, J. Zarbakhsh
In order to characterize the material behavior of copper films deposited on silicon substrate, wafer curvature experiments were performed. The samples were exposed to repeated cycles in the range between -50°C to 400°C. The diagrams of film stress versus temperature show linear film behavior followed by plastic flow. In fact, a pronounced Bauschinger effect was observed which is attributed to back-stress arising from the dislocation structure in copper films. For better understanding of the underlying mechanisms, a new statistical dislocation model was developed which can nicely be fitted to experiments. However, the algorithm of the dislocation model appeared to be very time consuming during computation. Therefore, a second model was developed which can refit the experimental data with high accuracy using a fast algorithm. We call this model pressure dependent combined isotropic and kinematic hardening. This model was implemented in ANSYS with user-subroutine usermat.
{"title":"Constitutive modelling of copper films on silicon substrate","authors":"Martin Lederer, J. Zarbakhsh","doi":"10.1109/EUROSIME.2015.7103130","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103130","url":null,"abstract":"In order to characterize the material behavior of copper films deposited on silicon substrate, wafer curvature experiments were performed. The samples were exposed to repeated cycles in the range between -50°C to 400°C. The diagrams of film stress versus temperature show linear film behavior followed by plastic flow. In fact, a pronounced Bauschinger effect was observed which is attributed to back-stress arising from the dislocation structure in copper films. For better understanding of the underlying mechanisms, a new statistical dislocation model was developed which can nicely be fitted to experiments. However, the algorithm of the dislocation model appeared to be very time consuming during computation. Therefore, a second model was developed which can refit the experimental data with high accuracy using a fast algorithm. We call this model pressure dependent combined isotropic and kinematic hardening. This model was implemented in ANSYS with user-subroutine usermat.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"382 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133486753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103076
Jue Li, P. Myllykoski, M. Paulasto-Krockel
This paper focuses on two major thermomechanical reliability topics related to high power devices such as insulated gate bipolar transistor (IGBT) modules. Firstly, the stress-free status and the thermal residual stress of a typical power module are investigated by finite element method (FEM) analysis. After determining the thermal residual stresses at room temperature, thermal cycling (TC) and power cycling (PC) tests are conducted and simulated by FEM. Secondly, the thermal grease pump-out phenomenon is explicitly simulated via a combined FEM and smoothed particle hydrodynamic (SPH) method for the first time. SPH method shows great potential for the thermal grease material selection and engineering, base plate optimization, and thermomechanical reliability optimization of power devices in general. The simulated contact opening results at the interface between copper base plate and heat sink indicates different pumping modes associated with different loading conditions. All modeling approaches presented in this work offer insight into our understanding of deformation, stress status, and thermal grease related failure mechanisms of high power devices.
{"title":"Study on thermomechanical reliability of power modules and thermal grease pump-out mechanism","authors":"Jue Li, P. Myllykoski, M. Paulasto-Krockel","doi":"10.1109/EUROSIME.2015.7103076","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103076","url":null,"abstract":"This paper focuses on two major thermomechanical reliability topics related to high power devices such as insulated gate bipolar transistor (IGBT) modules. Firstly, the stress-free status and the thermal residual stress of a typical power module are investigated by finite element method (FEM) analysis. After determining the thermal residual stresses at room temperature, thermal cycling (TC) and power cycling (PC) tests are conducted and simulated by FEM. Secondly, the thermal grease pump-out phenomenon is explicitly simulated via a combined FEM and smoothed particle hydrodynamic (SPH) method for the first time. SPH method shows great potential for the thermal grease material selection and engineering, base plate optimization, and thermomechanical reliability optimization of power devices in general. The simulated contact opening results at the interface between copper base plate and heat sink indicates different pumping modes associated with different loading conditions. All modeling approaches presented in this work offer insight into our understanding of deformation, stress status, and thermal grease related failure mechanisms of high power devices.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121868453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103140
K. Adokanou, K. Inal, P. Montmitonnet, F. Courtade, B. Bonnet
Accelerated life tests on microelectronic devices are needed to estimate their degradation under severe environment. THB (Temperature Humidity Bias) [1] at 85°C and 85%RH (relative humidity) is commonly used for reliability studies. Empirical acceleration laws, used for THB test take into account the temperature change (from 22°C to 85°C), but they do not quantify its impact of the corresponding thermo-elastic stress which it adds to the residual stress in the die and of possible microstructure changes. The aim of this work is to determine the thermo-mechanical stresses induced in the active layer of a Gallium Arsenide (GaAs) chip by the THB test. They are due to the mismatch in Coefficients of Thermal Expansion (CTE) between the stack of thin film materials used as metallurgic interconnection and the intermediate dielectric layers above the active area of the chip. To estimate this stress, fist layers thicknesses measurement have been made with various techniques; second few configurations have been used to simulate heating and finally “complete” 2D Finite Element Analysis (FEA) has been performed. Elastic and thermo-physical materials data come from the literature. The results indicate compression of metal gate (Ti/Al/Au) and tensile stress concentration in the SiNx passivation layer. The outcomes is compared with THB test results from [2] and suggests that stress induced by heating must be considered to explain failure during THB test.
{"title":"Thermo-mechanical analysis of GaAs devices under temperature-humidity-bias testing","authors":"K. Adokanou, K. Inal, P. Montmitonnet, F. Courtade, B. Bonnet","doi":"10.1109/EUROSIME.2015.7103140","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103140","url":null,"abstract":"Accelerated life tests on microelectronic devices are needed to estimate their degradation under severe environment. THB (Temperature Humidity Bias) [1] at 85°C and 85%RH (relative humidity) is commonly used for reliability studies. Empirical acceleration laws, used for THB test take into account the temperature change (from 22°C to 85°C), but they do not quantify its impact of the corresponding thermo-elastic stress which it adds to the residual stress in the die and of possible microstructure changes. The aim of this work is to determine the thermo-mechanical stresses induced in the active layer of a Gallium Arsenide (GaAs) chip by the THB test. They are due to the mismatch in Coefficients of Thermal Expansion (CTE) between the stack of thin film materials used as metallurgic interconnection and the intermediate dielectric layers above the active area of the chip. To estimate this stress, fist layers thicknesses measurement have been made with various techniques; second few configurations have been used to simulate heating and finally “complete” 2D Finite Element Analysis (FEA) has been performed. Elastic and thermo-physical materials data come from the literature. The results indicate compression of metal gate (Ti/Al/Au) and tensile stress concentration in the SiNx passivation layer. The outcomes is compared with THB test results from [2] and suggests that stress induced by heating must be considered to explain failure during THB test.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125089770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103127
M. Yazdan Mehr, W. V. van Driel, G. Zhang
A high accelerated stress testing (HAST) system is introduced to study the photo-thermal stability and reliability of remote phosphor plates, made from Bisphenol-A polycarbonate (BPA-PC) and YAG. Remote phosphor plates, combined with a blue-light LED source, are used to produce white light with a correlated colour temperature (CCT) of 4000 K. In this study, the remote-phosphor BPA-PC samples of 3 mm thickness were photo-thermally aged at temperature range 80 to 120 °C. The blue light is radiated on the sample with light intensity of 13200 W/m2. Thermal quenching of the YAG samples is also studied. It is shown that crystallographic structure of phosphor is stable during thermal ageing.
{"title":"Accelerated reliability test method for optics in LED luminaire applications","authors":"M. Yazdan Mehr, W. V. van Driel, G. Zhang","doi":"10.1109/EUROSIME.2015.7103127","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103127","url":null,"abstract":"A high accelerated stress testing (HAST) system is introduced to study the photo-thermal stability and reliability of remote phosphor plates, made from Bisphenol-A polycarbonate (BPA-PC) and YAG. Remote phosphor plates, combined with a blue-light LED source, are used to produce white light with a correlated colour temperature (CCT) of 4000 K. In this study, the remote-phosphor BPA-PC samples of 3 mm thickness were photo-thermally aged at temperature range 80 to 120 °C. The blue light is radiated on the sample with light intensity of 13200 W/m2. Thermal quenching of the YAG samples is also studied. It is shown that crystallographic structure of phosphor is stable during thermal ageing.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127109605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103126
Sridhar Kumar, U. Zschenderlein, R. Pantou, T. Brunschwiler, G. Schlottig, F. Schindler-Saefkow, B. Wunderle
To satisfy the increasing need in today's industry for high performance, more complex chips are being designed. These chips, when integrated in 3D packages, have a high energy density and require new and innovative cooling strategies as many of them are designed as flip-chip assemblies, usually requiring back-side cooling. Classical underfills currently used offer poor thermal conductivity. But cooling through the underfill would enable cost-efficient and low complexity cooling solutions. For this purpose, thermal underfills with percolating fillers and necks are currently under development. They are to provide a significant improvement in thermal conductivity to classical capillary underfills and will find applications in, for example, 3D integrated packages to improve heat dissipation. The idea behind the percolating thermal underfill (PTU) comprises a sequential joint forming process ensuring a high fill fraction. Although flip chip technology has been well described, the addition of the neck based percolating underfill could entail several new thermo-mechanical reliability concerns that need to be studied using a physics of failure approach, since the PTU exhibits vastly different thermo-mechanical behavior, giving rise to possible new failure mechanisms and locations. This paper in particular deals with FE simulations carried out to understand different key aspects of the thermal underfill and to study the effects of the increased underfill stiffness at these locations. The simulations are implemented using detailed elastic, plastic, visco-elastic and visco-plastic material data. In case of larger models a complexity reduction is required and implemented by using effective material data to improve computational time.
{"title":"Advances in percolated thermal underfill (PTU) simulations for 3D-integration","authors":"Sridhar Kumar, U. Zschenderlein, R. Pantou, T. Brunschwiler, G. Schlottig, F. Schindler-Saefkow, B. Wunderle","doi":"10.1109/EUROSIME.2015.7103126","DOIUrl":"https://doi.org/10.1109/EUROSIME.2015.7103126","url":null,"abstract":"To satisfy the increasing need in today's industry for high performance, more complex chips are being designed. These chips, when integrated in 3D packages, have a high energy density and require new and innovative cooling strategies as many of them are designed as flip-chip assemblies, usually requiring back-side cooling. Classical underfills currently used offer poor thermal conductivity. But cooling through the underfill would enable cost-efficient and low complexity cooling solutions. For this purpose, thermal underfills with percolating fillers and necks are currently under development. They are to provide a significant improvement in thermal conductivity to classical capillary underfills and will find applications in, for example, 3D integrated packages to improve heat dissipation. The idea behind the percolating thermal underfill (PTU) comprises a sequential joint forming process ensuring a high fill fraction. Although flip chip technology has been well described, the addition of the neck based percolating underfill could entail several new thermo-mechanical reliability concerns that need to be studied using a physics of failure approach, since the PTU exhibits vastly different thermo-mechanical behavior, giving rise to possible new failure mechanisms and locations. This paper in particular deals with FE simulations carried out to understand different key aspects of the thermal underfill and to study the effects of the increased underfill stiffness at these locations. The simulations are implemented using detailed elastic, plastic, visco-elastic and visco-plastic material data. In case of larger models a complexity reduction is required and implemented by using effective material data to improve computational time.","PeriodicalId":250897,"journal":{"name":"2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129754818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-19DOI: 10.1109/EUROSIME.2015.7103158
H. Kang, Jong Dae Lee, Joon Ki Kim, Yeong-Kook Kim
A side airbag sensor packaging directlly attached to the side frame (center pillar) of automobiles by adhesive is introduced in this study. To assess the feasibility for the packaging, a test instrument was manufactured to examine the impact sensibility by drop tests. The conventional sensor module with plastic housiung and the new sensor packaging were installed to aluminum channel, and the results were compared with each other. Numerical analyses were also performed to investigate the signal characteristics created by the sensors. The prerliminary results showed that the signals from the directly attached sensors represented more distinctive with less noise, presummably due to the absence of the vibration caused by the housing structure of the conventional sensor.
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