2012 14th International Conference on Electronic Materials and Packaging (EMAP)最新文献

{"title":"Highly transparent conducting graphene films produced by langmuir blodgett assembly as flexible electrodes","authors":"Xiuyi Lin, Jingjing Jia, Nariman Yousefi, Xi Shen, Jang‐Kyo Kim","doi":"10.1109/EMAP.2012.6507924","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507924","url":null,"abstract":"This paper reports the development of an efficient method to produce transparent conductive graphene films layer-by-layer on a flexible substrate based on the Langmuir Blodgett (LB) assembly technique. Monolayer ultralarge graphene oxide (UL-GO) sheets of average lateral size greater than 300 µm2 are prepared by repeated centrifugation of as-prepared GO aqueous dispersion. GO films having different numbers of GO layers are fabricated using the LB method while controlling the LB trough surface pressure and pulling speed of the substrate from the dispersion. GO films are chemically reduced at 90°C using hydrogen iodide (HI) acid, followed by chemical doping treatments. The sheet resistance values of the graphene thin films on a PET film are 1.8 and 1.1 kΩ/sq for 2 and 4 graphene layers, respectively, with a transparency of higher than 90%, which are sufficient for many useful applications. It is found that the thicker the film, the higher the conductivity; and vice versa for the transparency of the graphene films.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128423629","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}

{"title":"An atomistic scale study on solidification in ultrafine interconnects","authors":"Zhiyong Wu, Zhiheng Huang, P. Conway, Qingfeng Zeng","doi":"10.1109/EMAP.2012.6507903","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507903","url":null,"abstract":"The electronic packaging technologies have been developed into the three-dimensional era to fulfill the increasing demands for lightweight, portable products. Recently, nano mamterials and structures have been investigated extensively to enable interconnection in microscale or even submicron scale. However, it is still challenging to establish the link between the atomistic scale structures to the properties of the nano materials. In addition, the physical mechanisms involved in the adoption of the nano materials have not yet been fully understood. This work presents an atomistic scale study on the solidification process in ultrafine interconnects using a phase field crystal method. The solidification rate, the grain boundary formation and the atomistic arrangement in the interconnects of different geometries are discussed. Simulation results show that the nuclei in the barrel-shaped and the rectangular joints grow faster than those in the hourglass-shaped joints. In addition, the grain boundary formation in the interconnects differs in different geometries. It is found that one of the grain boundaries in the hourglass-shaped interconnect is shifted compared to that in the thinner hourglass-shaped interconnects. Furthermore, the displacements between atoms in the simulated atomistic microstructure relative to the perfect lattice are plotted to show the geometry effect on the atomistic arrangement. Results show that the magnitude of the displacements depends on the geometry of the interconnects, and that the pattern of the stream-line plot of displacements is influenced by the position of the nucleus.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122331688","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}

{"title":"Highly sensitive strain sensor using carbon nanotube","authors":"H. Kawakami, Ken Suzuki, H. Miura","doi":"10.1109/EMAP.2012.6507923","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507923","url":null,"abstract":"A new highly sensitive strain sensor has been developed by applying the strain-induced change of the electrical conductivity of multi-walled carbon nanotubes (MWCNTs). The electric conductivity of MWCNTs changes drastically under uni-axial strain because of the drastic change of their electronic band gap. Therefore, the local strain distribution can be detected by measuring the change of the electric resistance of MWCNTs under strain. In order to design a new sensor using MWCNTs, a method for controlling the shape of the MWCNTs was developed by applying a chemical vapor deposition (CVD) technique. It was found that the shape of the grown MWCNTs can be controlled by changing the average thickness of the catalyst layer and the growth temperature. The electrical resistance of the grown MWCNT bundle changed almost linearly with the applied uniaxial compressive strain, and obtained maximum strain sensitivity was about 10%/1000-ustrain (gauge factor: 100). A two-dimensional strain sensor, which consisted of area-arrayed fine bundles of MWCNTs, was developed by using MEMS technology. Under the application of compressive strain, the electric resistance was confirmed to increase almost linearly with the applied strain.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127750143","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}

{"title":"Development of innovative cold pin pull test method for solder pad crater evaluation","authors":"Qiming Zhang, Chaoran Yang, Mian Tao, F. Song, S. Lee","doi":"10.1109/EMAP.2012.6507880","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507880","url":null,"abstract":"Hot pin pull test is one of the testing methods frequently used in the pad crater evaluation. Although it carries several merits comparing with the other testing methods, it still has certain drawbacks such as time consuming and the potential thermal impact on the PCB copper pad during the pin attachment process. In this paper, an innovative cold pin pull testing method is introduced. Using a set of fixtures designed and manufactured in advance, an array of pins can be attached to the pre-deposited solder balls at one time. Therefore, instead of attaching the pin one by one, the test panel with pin arrays can be prepared after only two times of reflow. Compared with conventional cold ball pull tests, this newly developed method can not only equally exhibit the pad crater characteristics of the PCB, but also reduce the testing variations, which could be proven by experimental data generated in the present study.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131329550","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}

{"title":"Effects of microstructure on vacancy and stress distributions in micro joints under current stressing","authors":"Hua Xiong, Zhiheng Huang, P. Conway, Qingfeng Zeng","doi":"10.1109/EMAP.2012.6507913","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507913","url":null,"abstract":"The vacancy diffusion and stress evolution in SnPb and SnCu micro solder joints under current stressing are studied based on simulated microstructure from a phase field model. The vacancies are driven to the cathode by electric current and accumulated in the phase with lower vacancy formation energy. Stress concentration is predicted at the interfaces between phases, which is more severe when more vacancyplated atom pairs are generated or annihilated. Compared to the Sn15Cu joint, there are more vacancies accumulated and annihilated at the cathode of the Sn27Pb joint and thus resulting in a higher von Mises stress. The effects of phase morphology on electromigration are further investigated. It is found that the decrease of the amount of interface due to phase coarsening in the Sn37Pb micro joint can accelerate vacancy accumulation. As a result, during electromigration the stress can quickly increase in the joint aged for a longer time. In addition, the connectivity of the Pb-rich phase also affects the electromigration behavior. A well-interconnected network of Pb-rich phase can accelerate the vacancy accumulation and thus stress concentration. Due to the combined effect of the connectivity of Pb-rich phase and the amount of interface, the maximum stresses caused by electromigration in three joints of different compositions, i.e. Sn47Pb, Sn37Pb, and Sn27Pb, are in the order of Sn37Pb>Sn47Pb>Sn27Pb. Introduction The risk of electromigration-induced failure increases in three-dimensional integrated circuits, due to a high current density in company with the miniaturization of interconnects. In order to improve reliability, the mechanisms causing failure due to electromigration need to be understood. As a form of mass diffusion driven by electron flow, the process of electromigration interacts with the microstructures in interconnects in a complicated way. The rate of electromigration can be influenced by microstructural features such as crystal grains, grain boundaries, and different phases, where the atom diffusivities are different [1,2]. The atom fluxes driven by electric current can in turn affect microstructural evolution [3,4]. It is of significant importance to consider the effects of microstructures on an accurate prediction of the electromigration behavior in interconnects. Extensive simulation studies on electromigration have been carried out for Cu and Al interconnects [5]. However, electromigration simulations for micro solder joints, especially those based on microstructure, are relatively few. Compared to Cu and Al, most micro joints are composed of binary or ternary alloys and possess microstructures with a multicomponent and multi-phase nature. Interdiffusion occurs in micro joints, which can lead to many failure modes, e.g. the rapid dissolution of Cu under-bump metallization [6], and the formation of Kirkendall voids [7]. In addition, fast diffusion of atoms can occur along the interfaces between different phases as well as along","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131203530","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}

{"title":"The role of thermal properties of PCB substrates in heat dissipation of LED back light bars","authors":"C. Y. Tang, J. J. Huang, Y. Peng, M. Tsai, P. Liang","doi":"10.1109/EMAP.2012.6507882","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507882","url":null,"abstract":"With special features of high color rendering index, environmental friendliness, low power consumption, long lifetime, small form factor, and short response time, the light emitting diode (LED) has gradually been replacing the conventional cold cathode fluorescent lamp (CCFL) as a back lighting source in TV and computer monitors industry. However, the high junction temperature (Tj) in the LED chips would be detrimental for its service life and reliability. Thereby, the thermal management of the LED back light bars is an important issue. The goal of this study is to experimentally and numerically study the effect of PCB substrates on the thermal performance of the LED back light bars, shown in Fig. 1. In these light bars, the commercial LED packages with a size of 5.7 mm × 3 mm × 1 mm are mounted on various 6.3 mm-wide PCB strip substrates with a pitch of 8.50 mm. Four types of the PCB substrates with different layer up and thermal properties are evaluated in term of Tj and thermal resistance experimentally by junction temperature tester, shown in Fig. 2, and numerically by CFdesign simulation (one of commercial computational fluid dynamic codes). The effect of PCB substrates on Tj and thermal resistance of the LED light bars will be demonstrated and its mechanism will be investigated and interpreted based on experimental and numerical simulation results. In addition, the effective thermal conductivity of the PCB substrates will be proposed for easy calculation, evaluation and comparisons.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115728662","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}

{"title":"Volume effect on interfacial microstructure and mechanical properties of Ni(UBM)/Sn3.0Ag0.5Cu/Ni(UBM) joints","authors":"Jing-Bo Zeng, Guang-Sui Xu, Min-bo Zhou, Xin-Ping Zhang","doi":"10.1109/EMAP.2012.6507872","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507872","url":null,"abstract":"The effect of solder volume on the interfacial microstructure and mechanical properties of micro-scale line-type Ni/Sn3.0Ag0.5Cu/Ni joints was investigated. Ni wires of 300 µm in diameter were used as under-bump-metallization (UBM) to be connected by Sn3.0Ag0.5Cu solder balls. The solder joints were assembled by modeling the thermal cycle of the reflow process with the accurately controlled assembly joint gap (i.e., joint thickness or height) of 100, 75, 50 and 25 µm, respectively. The mechanical behavior of the joints was evaluated by a dynamic mechanical analyzer (DMA) under uniaxial tensile loading. The interfacial microstructure and fractographic morphologies of the joints were analyzed by SEM equipped with EDS. Results show that both (Ni,Cu)3Sn4 and (Cu,Ni)6Sn5 IMC phases formed at the interface of all the as-assembled solder joints regardless of solder volume or joint thickness, i.e., the solder volume has little influence on the interfacial reaction products. Furthermore, with decreasing the joint thickness, tensile strength of the joints increases obviously. Fractographic morphology analysis results indicate that there are three different failure modes, that is, ductile, quasi-brittle and brittle mode. The joints with thicknesses of 100 and 75 µm all failed in a ductile failure mode, the joints with a thickness of 50 µm failed in both ductile and quasi-brittle mode, while for the joints with a very small thickness of 25 µm, brittle fracture happened and quasi-brittle failure mode still possessed the most part.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121744261","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}

{"title":"Preparation of MWCNT-Ni0.5Zn0.5Fe2O4-Epoxy composites with both dielectric and ferromagnetic properties","authors":"Qi Zheng, Pengli Zhu, R. Sun, C. Wong","doi":"10.1109/EMAP.2012.6507833","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507833","url":null,"abstract":"In this work, ferromagnetic Ni0.5Zn0.5Fe2O4 (NZF) particles were prepared through the co-precipitation method. Then, dielectric ferromagnetic composites with multi-walled carbon nanotubes (MWCNT) and NZF embedded into E-51 Epoxy matrix were synthesized by a curing process using tetraethylenepentamine (TEPA) as the curing agent. In order to facilitate the contrast, the volume fraction of the NZF ferrite was fixed at 17%, and the permeability and permittivity of the composites have been investigated in detail with the Agilent 4294A from 40 Hz to 110 MHz. For the MWCNT filler, its one-dimensional structure and good electric properties could make the composites gain a great increase on dielectric constant. And the permittivity of the composites with fMWCNT=1.7% is twice higher than the composites with only NZF. Moreover, the permeability of all the composites nearly remains the same. All the above results indicate that the MWCNT-NZF-Epoxy composites own both dielectric and ferromagnetic properties.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"220 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124247595","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}

{"title":"Recent advances in Anisotropic Conductive Adhesives (ACAs) technology: Materials and processing","authors":"Kyung W. Paik","doi":"10.1109/EMAP.2012.6507831","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507831","url":null,"abstract":"New ACA materials and processing technologies innovation have been made at various advanced packaging applications such as FOB, FOF, COF, COG, TSP (Touch Screen Panel) and 3D-TSV (Through Silicon Via) assemblies.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128951831","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}

{"title":"Development of low temperature Chip-on-Flex (COF) bonding process of 100°C","authors":"Sun-Chul Kim, Young-Ho Kim","doi":"10.1109/EMAP.2012.6507904","DOIUrl":"https://doi.org/10.1109/EMAP.2012.6507904","url":null,"abstract":"Recently, many researchers have introduced low temperature bonding technology using Anisotropic conductive film (ACF) or Nonconductive adhesive (NCA). In their studies, the bonding temperature is in the range between 150°C and 200°C. In this study, we developed a Chip-on-Flex (COF) bonding process of 100°C by using Sn-Ag bumps and nonconductive film (NCF). Sn-Ag bumps were formed by electroplating and reflowed to form dome shape. The COF bonding was performed between Sn-Ag bumps and Cu/Polyimide film substrates using a thermo-compression bonder at 100°C for 5 s. The low temperature curable NCF was applied during the bonding process. The Sn-Ag bumps were deformed and direct contact was made between Sn-Ag bumps and Cu/PI substrate during thermo-compression bonding. The initial contact resistance of all joints was less than 30 mΩ, and no COF joints failed electrically. To evaluate reliability of COF joints, Temperature & Humidity (T&H) test (85°C/85% RH) was performed for 1000 hr. The contact resistance was increased during reliability test. However, the failed joints were not observed after T&H test. The contact resistance change will be discussed in terms of microstructure change in the COF joints.","PeriodicalId":182576,"journal":{"name":"2012 14th International Conference on Electronic Materials and Packaging (EMAP)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129778836","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}