高校基层党组织是高校确保深入贯彻党的教育路线方针政策的坚强基础,是高校治理工作的推广者、执行者、带头者和依靠者,具有重要的政治功能和组织功能.以党建引领提升高校基层治理效能,是扎根中国大地办大学的根本要求,更是推进"双一流"建设的重大课题.全面促进高校基层党组织的政治优势和组织优势转化为治理效能,要着力从发挥党员主体力量、完善党政发展机制和坚持以师生为中心等方面发力,科学有效提升党建对高校基层治理的引领作用.

当前正处于大数据变革时代, “互联网”与传统行业深度融合,逐渐形成了“互联网+X”创新模式.用“互联网+”思维引领党建工作,是党组织顺应时代潮流、提升执政能力和执政水平的必然选择.本研究基于“互联网+”创新发展模式,围绕智慧党建工作开展,对智慧党建新模式进行分析和探索.

校园媒体作为高校开展党建思政工作的重要媒介之一,本着“四个立足” “四个促进”的宗旨,立足于党建思政、引导、校园、服务四大阵地,在宣传阵地建设、舆论正确导向、校园文化繁荣和研究生身心协调发展方面起到了良好的促进作用.本文以《上海大学研究生报》为例,重在探索校园媒体建设对党建思政工作的作用和影响路径.

当前,我国研究生教育规模不断扩大,新媒体兴起并逐渐成为开展研究生思政教育的重要途径.如何认识新媒体的地位与特点,进而发挥其在研究生思政教育中的功能和作用,本文结合新媒体工作实践进行阐述,就如何进一步加强新媒体建设提出了相关见解.

"双创"作为当前热点话题之一,受到国家、政府、企业及高校的密切关注和重视.以上海市19所研究生培养单位,327名参与过科创实践竞赛的研究生为研究对象,实证探讨了科创实践型研究生创业教育、创业自我效能感对创业意向的影响.在一定程度上为培养研究生双创能力和实践提供支持与参考.

红色记忆是关于近代中国革命历程的集体记忆,对于大学生有重要的教育意义.学校和社会可以通过重温入党誓词、 组织学生担任革命纪念馆志愿者以及宣传红色档案等形式对大学生进行红色教育,同时,借助课堂和社交媒体等途径大力弘扬红色历史与红色记忆,以增强大学生的历史认同和文化自信.

The morphology and growth behavior of interfacial intermetallic compound (IMC) layer for the Sn3.0Ag0.5Cu0.05Cr (SACCr)/Cu joints after isothermal aging at 150 degrees C for 0, 168, 500 and 1000 h were investigated, and they were compared with Sn3.0Ag0.5Cu (SAC). The results show that the trace Cr dispersed or dissolved in SAC solder effectively inhibits the IMC layer growth at the interface of SACCr/Cu joints. The longer the aging time, the more obvious the inhibiting effect of Cr on the overgrowth of IMC layer of solder/Cu joints. The average thickness of IMC layer of SACCr/Cu solder joints is about 5.13 mu m after aging for 1000 h, only 45% of that of the SAC/Cu solder joints.

Purpose – The purpose of this study was to comparatively investigate interfacial intermetallic compounds (IMCs) in the Sn3.0Ag0.5Cu3.0Bi0.05Cr/Cu (SACBC/Cu) and Sn3.0Ag0.5Cu/Cu (SAC/Cu) solder joints, and to determine any differences. Design/methodology/approach – The samples were annealed after isothermal ageing at 150°C for 0, 168 and 500 hours, and their cross-sections were observed by scanning electron microscopy and energy dispersive spectroscopy. Findings – The interfacial IMC morphology in two joints had significant differences. For the Cu/SAC/Cu joints, the granular and short rod-like Ag3Sn particles attached on the surface and boundary of interfacial Cu6Sn5 grains were detected, and they coarsened observably with ageing time at 150°C, and lastly embedded at the grain boundaries. However, for the Cu/SACBC/Cu joints, there were tiny filamentous Ag3Sn growing on the surface of interfacial Cu6Sn5 grains, and the Ag3Sn had a tendency to break into nanoparticles, which would be distributed evenly and cover the IMC layer, profiting from the Bi and Cr precipitates from solder matrix during ageing. Originality/value – The paper implies that the addition of Bi and Cr could affect the IMCs of joints, thereby delaying interfacial reactions between Sn and Cu atoms and improving the service reliability. The SACBC solder is a potential alloy for electronic packaging production.

PurposeIn a previous study, the authors proposed a new low‐silver solder alloy Sn‐ x(1.0, 1.5, 2.0)Ag‐0.3Cu‐3.0Bi‐0.05Er (wt.%) (SACBE) and the purpose of this paper is to provide additional useful information for new solder alloy development. The growth behaviour of the interfacial IMC layers for Cu/SACBE/Cu and Cu/SAC/Cu joints and their bonding strengths after thermal aging at 150°C for 0, 24, 168 and 500 hours are investigated and the effects of adding elemental Bi and Er on the growth of interfacial IMC layers in the joints, and their tensile properties, are characterized and discussed.Design/methodology/approachThe tensile properties of the Cu/Sn‐3.0Ag‐0.5Cu/Cu (Cu/SAC/Cu) and Cu/SACBE/Cu joints during thermal aging at 150°C for 0, 24, 168 and 500 hours were investigated, respectively. The thickness of interfacial IMC layer and the fracture surface of solder joint after isothermal aging were observed and analyzed by means of scanning electron micrograph (SEM) equipped with an energy dispersive spectroscopy X‐ray (EDX) analysis system.FindingsIt was found that the thickness of the IMC layer at the interface of a Cu/SACBE/Cu joint was remarkably thinner than that of a Cu/SAC/Cu joint. The addition of Bi and Er could significantly improve the tensile properties of the solder joint and enhance its resistance to high temperature aging. A mixture of ductile and brittle fracture mode was observed after tensile testing in the Cu/SACBE/Cu joints.Originality/valueThe paper implies that the addition of Bi and Er could complement effectively the effects of Ag, thereby reducing the cost of solder. The low‐silver SACBE solder is a potential alloy for electronic packaging production.

In this paper, the interfacial microstructure evolution of three Cu/solder/Cu joints with thermal aging at 150°C for 0, 168, and 500 hours respectively were studied using SEM+EDS. The object of study was the self-prepared Sn3.0Ag0.3Cu0.05Cr (SACC) and Sn3.0Ag0.5Cu3.0Bi0.05Cr (SACBC) and the common industrial Sn3.0Ag0.5Cu (SAC) solder was selected as the benchmark for comparison. The IMCs (intermetallic compounds) with different morphologies at the joint interfaces were enumerated and described. Results showed that most of Cu 6 Sn 5 was rod-like, while Ag 3 Sn was needle-like in three solder matrix of joints. The interfacial Cu 6 Sn 5 growth of Cu/SAC/Cu joint during soldering was not in a typical scallop-shaped model, but in a so-called “bamboo shoots”. For three joints after soldering, the Cu 6 Sn 5 in Cu/SACC/Cu joint had the smallest size and most fine strip-like Ag 3 Sn was observed near the interfacial IMC layer, which could be attributed to the Cr addition and the redistribution of elements controlled by atomic diffusion along phase interfaces. It was also found that, differing from the coarsened granular Ag 3 Sn at the Cu 6 Sn 5 grain boundaries in Cu/SAC/Cu joints after aging, the tiny filamentous Ag 3 Sn at the interface of Cu/SACBC/Cu joint had a tendency to break into nano or ultrafine particles evenly distributed on the surface of Cu 6 Sn 5 . Bi particles with nano size precipitated from solder matrix due to Sn consumption forming IMCs.

The fusion characteristics, wettabilities and mechanical properties of the new low-silver lead-free solder Sn-XAg -0.3Cu-3Bi-0.05Er (SACBE) (X=1.0, 1.5, 2.0) were studied by DSC, wettability experiment and tensile test. The results show that the developed SACBE solder has better properties in comparison with commercial Sn-3.0Ag-0.5Cu (SAC) solder, featuring a lower melting temperature, a better wetting performance and excellent toughness. It implies that the developed SACBE solder is a potential one for electronic packaging production.

The evolution of IMCs in SACBC/Cu solder joint and its tensile property after isothermal aging at 150 ° for 0, 168 and 500 h were investigated. The hollow blocky phase containing Cr was observed in the solder matrix of the joint after soldering, which was not found after aging. The needle-like Ag3Sn transformed to be short rod-like or ellipsoidal during aging. Bright and sphericized Bi particles precipitate at the interface and suppress overgrowth of IMCs layer, resulting in a relative stable tensile strength.

A new lead-free solder alloy Sn3Ag0.5Cu-3Bi-0.05Cr (SACBC) was prepared by adding approximately 3.0% Bi and 0.05% Cr in Sn3Ag0.5Cu(SAC) solder. The mechanical properties and the behavior of interfacial intermetallic compound (IMC) for the solder joints of SAC/Cu substrate and SACBC/Cu substrate during isothermal aging at 150 degrees C for 0, 24, 168, 500 and 1000 h respectively were comparatively investigated. The results show that the SACBC alloy has a better melting range of 210 similar to 217 degrees C. The tensile strengths of Cu/SACBC solder joints are obviously superior to Cu/SAC, whether as-soldered or isothermal aged. The strength for the former. solder joints is reduced by 4.2 MPa after aging 168 h at 150 degrees C and it is decreased by only 5 MPa after 1000 h, compared to the strength at as-soldered state. But for the latter one, the strength declines significantly with the extension of thermal aging time and finally after 1000 h, it holds only half of the strength of the as-soldered. The morphology of the tensile fracture for Cu/SACBC solder joints transforms from a quasi-cleavage fracture surface to a cleavage-like brittle surface. The new solder can inhibit the overgrowth of IMC effectively.

The mechanical properties and interfacial microstructure of Cu/Sn3Ag0.5Cu3Bi0.05Cr/Cu (Cu/SACBC/Cu) and Cu/Sn3.0Ag0.5Cu/Cu (Cu/SAC/Cu) joints were comparatively investigated after isothermal aging at 85 °C, 120°C and 150°C for 24, 168, 500 and 1000 h, respectively. The mechanism of Bi addition affecting the intermetallic compounds (IMCs) growth was discussed. Results show that the tensile strength of Cu/SACBC/Cu and Cu/SAC/Cu joints both decreased exponentially with aging time at any temperature and declined linearly with the increased temperature, while the rate of strength decrease for the former joint was lower with an order of magnitude. The SEM observation on the tensile fracture surfaces for Cu/SACBC/Cu joints shows that the tensile fracture mechanism transformed from a quasi-cleavage fracture to a cleavage-like brittle fracture after aging at 150 °C, while quasi-cleavage fracture is the main fracture mode for 120 °C and 85 °C. The relative stable tensile strength for Cu/SACBC/Cu joints can be attributed to thinner interfacial layer and strengthened Sn matrix with the solution strengthening and precipitating effects of Bi. The growth behaviors of interfacial IMCs were similar after aging at 150°C, 120°C and 85°C.

The intermetallic compounds (IMC) in the solder and at the interface of Sn-3.0Ag-0.5Cu (SAC)/Cu and Sn-3.0Ag-0.3Cu-0.05Cr (SACC)/Cu joints were investigated after isothermal aging at 150 degrees C for 0, 168 and 500 h. Different shaped Ag3Sn phases were found near the IMC layer of the latter joint. Interestingly, fine rod-shaped and branch-like Ag3Sn were detected near the interface after soldering and long Ag3Sn changed into shorter rods and small particles during aging. It is investigated that the Cr addition and thermal aging have effect on the evolution of Ag3Sn morphologies and it is controlled by interfacial diffusion. Energy minimization theory and the redistribution of elements are used to explain the morphological evolution of Ag3Sn. Small Ag3Sn particles were also found on the IMC layer after aging, unlike the large Ag3Sn at that of SAC/Cu joints. In conclusion, a favorable morphology of the joint interface leads to better bonding properties for SACC/Cu joints against thermal aging than that for SAC/Cu. (C) 2011 Elsevier B. V. All rights reserved.

A new lead-free solder alloy Sn3Ag0.5Cu3Bi0.05Cr (SACBC) was prepared by adding 3.0 wt.% Bi and 0.05 wt.% Cr on the basis of the composition of Sn3Ag0.5Cu(SAC). The tensile strength and the growth behavior of the interfacial intermetallic compound (IMC) of SAC/Cu substrate and the SACBC/Cu solder joints during isothermal aging at 150 °C for 0, 24, 168, 500 and 1000 hours were comparatively investigated, respectively. The results showed that the SACBC alloy has a better melting temperature range of 210°C–217°C, comparing with that of the SAC. Due to the solid solution strengthening of Bi in Sn matrix, the tensile strength of the SACBC/Cu solder joints was obviously superior to that of the Cu/SAC, whether as-soldered or isothermal aged. The tensile strength of the Cu/SAC joints dramatically declined with aging time increasing, even after only aging for 24hr. The strength after 168h aging dropped by 32.1% comparing with that in as-soldered condition. When the aging time extended to 500hr, the strength decline slowed down and it held at 35 MPa, which was only about half of the original strength. On the contrary, the tensile strength decline for the Cu/SACBC joints was not noticeable and the strength almost kept stable from 168h to 1000h. Comparing with the as-soldered, it decreased by less than 5% after aging at 150 °C for 168h and only 5 MPa for 1000h (81.5 MPa). Therefore, 3.0 wt. % Bi and 0.05 wt. % Cr additions could significantly improve the solder joint bonding property and enhance the resistance to high temperature aging. The fracture mechanism for Cu/SACBC joints transformed from a quasi-cleavage to a cleavage-like brittle fracture. The developed new solder can effectively inhibit the overgrowth of IMC at the interface of the solder joints.

PurposeThe purpose of this paper is to compare the growth kinetics of interfacial intermetallic compound (IMC) layer and its effect on the tensile strength of two solder (Sn3.0Ag0.5Cu and Sn0.4Co0.7Cu) joints.Design/methodology/approachThe samples annealed, respectively, at 85, 120 and 150°C up to 1,000 h were tensile tested and their cross‐sections were observed by scanning electron micrography.FindingsThe results showed that, for both solder joints, an approximately linear reduction in tensile joint strength with an increase in the IMC layers' thickness occurred. The tensile strength of Cu/Sn3.0Ag0.5Cu solder joints is slightly better than that of Cu/Sn‐0.7Co‐0.4Cu solder joints under analogous aging conditions. In addition, the growth kinetics of the overall interfacial IMC layer in Sn0.4Co0.7Cu solder joints can be simply described by the classical growth kinetic theory for solid‐state diffusion with an activation energy of 2,996.85 J/mol and interdiffusion constant of 4.15×0−17 m2/s which are relatively lower, compared with Sn3.0Ag0.5Cu solder on copper with 14,167.8 J/mol and 65.33×10−17 m2/s, respectively.Originality/valueThe paper is of value in evaluating the growth kinetics of Sn3.0Ag0.5Cu and Sn0.4Co0.7Cu solder joints, and in discussing and contrasting the influence of IMC growth on their tensile strength.

Microstructural features and tensile properties of Sn-3.0Ag-0.5Cu solder joints on copper with various aging time at 150degC were examined. The solder inner and solder/Cu interface were analyzed by SEM to identify the fracture location, morphology and compositions. The study has showed, the tensile fracture strength of the solder joints decreases with the increased aging time, and the crack initiates mostly at the interfaces between the solder and IMC layer or/and IMC and IMC layer. The morphology of fracture surface changes from dimple-like to cleavage-like surfaces. The needle-like or block-like interfacial IMCs form at the interface of Cu/solder and grow into the solder matrix. Otherwise, the Kirkendall voids can be observed in the multilayer structure close to the copper substrate. These voids have probably a detrimental effect on the tensile fracture behavior.

The tensile fracture behavior and the intermetallic compound’s(IMC’s) morphology and composition at the interface of Cu/Sn-3.0Ag-0.5Cu/Cu solder joint specimens after aging at(150±1)℃ for 0-1 000 h were studied.The results show that,with the increasing aging time,the tensile fracture strength of the solder joints decreases and the crack initiates mostly at the interfaces between the solder and IMC layer or/and IMC and IMC layer.The morphology of fracture surface changes from dimple-like to cleavage-like surfaces.SEM analysis indicates that the needle-like or block-like interfacial IMC forms at the interface of Cu/solder and grows into the solder matrix.After being aged for 1 000 h,the obvious IMC multilayer structure is observed,which is defined as Cu/Cu3Sn/Cu6Sn5/solder structure for the half-joints.Moreover,the Kirkendall voids can be observed in the multilayer structure close to the copper substrate.These voids are possibly one of the factors of the tensile fracture mechanism.

The Sn-Zn based lead free solder appears to be an attractive alternative with a melting temperature relatively close to eutectic Sn-Pb.The addition of bismuth in Sn-Zn alloy improves its wettability and aluminum is beneficial to improve the oxidation resistance.The degradation of Sn-Zn based solder joints after exposed in the temperature and humid atmosphere with high pressure was studied.Three kinds of Sn-Zn system solders(Sn-9Zn,Sn-8Zn-3Bi and Sn-7Zn-Al(30×10~(-6))) were soldered on copper pad with a layer of Au/Ni and the specimens were stored in a pressure cooker for 96 or 192h.The temperature and the relative humidity in the cooker were 120℃ and 100% respectively.The mechanical fatigue test was carried in a displacement-controlled mode to measure the low cycle fatigue of the joints.The results show that Zn diffuses to the surface and interface while coarsening at the same time,and the coarser Zn has weak interface with β-Sn matrix and oxides form.High temperature and high humidity exposure decreases the mean life of Sn-Zn solder joints when they are subjected to 120℃ and 100% relative humidity with 2.03×10~5Pa pressure for 192h.