AuSn20共晶合金钎料制备工艺研究进展

AuSn20钎料以其优异的综合性能,广泛应用于高可靠微电子器件和光电子器件封装。但AuSn20共晶合金铸态组织的粗大和初生金属间化合物相分布的不均匀导致合金脆性较大,制备成形困难,其制备工艺是目前的研究热点。介绍了固态成形工艺、液态成形工艺、薄膜工艺和快速凝固工艺制备AuSn20钎料的原理和特点,指出了制备工艺的发展方向。     

Au-20Sn贵金属钎料箔材的制备及性能研究

采用多层复合及扩散合金化工艺制备Au-20Sn贵金属钎料箔材，研究箔材的化学成分、熔化特性、力学性能、物相组成、组织形貌和微区成分，并采用真空钎焊工艺对所制备钎料箔材的钎焊性能进行研究。结果表明，采用多层复合及扩散合金化工艺制备的Au-20Sn钎料箔材脆性明显改善，能够在室温下冷冲裁加工成特定尺寸的预成型焊片；钎料箔材的化学成分和杂质含量符合设计要求，显微组织由连续且均匀分布的(AuSn)和(Au5Sn)两相组成；钎料熔程仅为3.1 ℃，在铜基材上润湿性和铺展性良好，钎焊铜接头力学性能较好。     

AuSn钎料及AuSn/Ni焊点的组织性能研究

分别采用叠轧-合金化法和回流焊技术制备AuSn箔材钎料和AuSn/Ni焊点,用扫描电子显微镜及电子万能试验机研究钎焊时间对AuSn/Ni界面组织及焊点剪切性能的影响。结果表明:采用叠轧-合金化法制备的AuSn钎料的熔点和化学成分都接近Au-20Sn共晶钎料。Ni/AuSn/Ni焊点在330℃钎焊30s时形成良好的层状ζ-(Au,Ni)5Sn+δ-(Au,Ni)Sn共晶组织;钎焊60s时,AuSn/Ni界面产生薄而平直的(Ni,Au)3Sn2金属间化合物(IMC)层和针状(Ni,Au)3Sn2化合物;随着钎焊时间继续延长,(Ni,Au)3Sn2IMC层厚度明显增加,针状(Ni,Au)3Sn2化合物异常长大。同时,随着钎焊时间延长Ni/AuSn/Ni钎焊接头的剪切强度先增加后减小,钎焊90s时的剪切强度达到最高12.49MPa。     

新型中温金基钎料研究

研究了一种微电子器件高温封装用Au-In共晶型中温金基钎料合金,钎料由77%~75%Au和23%~25%In(质量分数)构成,规格为0.03~0.10?,钎料箔带材是采用多层叠加轧制方法制造的。实验结果表明,在保护气氛下,500~520℃无钎剂钎焊,钎料对镀金可伐合金和无氧铜、纯镍、纯银等多种母材具有优良的漫流性和间隙填充性,钎焊接头牢固、钎料箔带材塑性高,应用工艺性能良好。     

金锡合金钎料焊膏与箔材钎焊性能对比研究

研究和比较了自制金锡合金焊膏与金锡合金箔材的相关性能。实验结果表明:金锡合金钎料焊膏的铺展性及润湿性优于箔材钎料;接头的显微组织和结构基本相同;在大气条件下,焊膏的钎焊性能比箔材钎料好;焊膏的剪切强度略低于箔材钎料。     

激光重熔PBGA钎料球与Au/Ni/Cu焊盘的界面反应

研究了塑料球栅阵列（PBGA）钎料球重熔过程中钎料与Au/Ni/Cu焊接之间的界面反应，结果表明：界面处金属间化合物的生成与激光输入量能密切相关，当激光输入能量较小时，焊盘上的Au没有完全溶解到钎料中，界面处存在一层连续的AuSn2和一些垂直或斜向生长到钎料中的针状AuSn4化合物，增大激光输入能量，Au完全溶解到钎料中，界而处连续的AuSn2化合物层全部转化为针状AuSn4相，有部分AuSn4针从界面处折断并落入钎料中，当激光功率为18W，激光加热时间为400ms时，AuSn4相在界面处消失，以细小颗粒弥散分布在钎料内部。     

腐蚀损伤铝合金表面超声焊接截面组织结构分析

在腐蚀受损的2A12CZ基体上采用超声焊接铝合金箔材的工艺进行了修复处理,并利用光学显微镜观察和分析了焊接时间对箔材与基体之间焊接界面组织的影响。结果表明:当焊接时间为0.6s时,箔材与基体之间呈断续的结合状态,能分辨出结合界面,且界面呈锯齿状或涡流状分布;当焊接时间为1.2s时,箔材与基体之间完全结合成一体,界面消失,呈冶金结合状态。最后对铝合金箔材与铝合金基体之间超声焊接机理进行了探讨。     

IGBT封装用钎料的研究现状

当前,IGBT作为功率器件已经广泛地应用于许多工业领域。IGBT芯片和敷铜陶瓷基板(DBC)的封装普遍采用钎焊技术,因此,钎料的钎焊工艺性能、力学性能、导热性能在很大程度上决定了IGBT功率器件在服役时的性能稳定性和可靠性。文中根据国内外文献资料,分别介绍了铅基、锡基、金基、铋基钎料以及纳米银膏在IGBT功率器件封装上的应用状况,并对钎料今后的发展趋势进行了展望。     

退火工艺对Au-20Sn钎料组织的影响

采用叠轧-合金化法制备Au-20Sn钎料,研究合金化退火工艺对Au-20Sn钎料显微组织的影响。结果表明:Au/Sn界面在叠轧过程中形成AuSn4,AuSn2和AuSn三个金属间化合物(IMC)层。在200℃退火时,IMC层的厚度随退火时间的延长而逐渐增大。当退火时间延长至48 h时,IMC层发生转变,Au-20Sn钎料最终形成由ζ相(含Sn 10%～18.5%,原子分数)和δ(AuSn)相组成的均质合金。在250℃退火时,Au/Sn界面扩散速度增大,退火6 h后Au-20Sn钎料组织完全转变成ζ相+δ(AuSn)相。在270℃退火时,IMC层熔化,反应界面转变成为固-液界面,Au-20Sn钎料组织转变为脆性的(ζ’+δ)共晶组织。综合Au-20Sn钎料的性能和生产要求,得到优先退火工艺为250℃退火6 h。     

D-KH法制备金锡合金的组织与结构

通过D-KH法和熔铸法、急冷法制备的AuSn20合金相组成和相结构比较，表明了采用D—KH法制备的不同厚度AuSn20箔带和用3种方法制造的Ausn20合金的相组成和相结构完全相同。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

X80 pipeline steel plates were friction stir welded(FSW) under air, water, liquid CO_2 + water, and liquid CO_2 cooling conditions, producing defect-free welds. The microstructural evolution and mechanical properties of these FSW joints were studied. Coarse granular bainite was observed in the nugget zone(NZ) under air cooling, and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature reduced. In particular, under the liquid CO_2 cooling condition, a dual phase structure of lath martensite and fi ne ferrite appeared in the NZ. Compared to the case under air cooling, a strong shear texture was identifi ed in the NZs under other rapid cooling conditions, because the partial deformation at elevated temperature was retained through higher cooling rates. Under liquid CO_2 cooling, the highest transverse tensile strength and elongation of the joint reached 92% and 82% of those of the basal metal(BM), respectively, due to the weak tempering softening. A maximum impact energy of up to 93% of that of the BM was obtained in the NZ under liquid CO_2 cooling, which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.     

INDUSTRY NEWS

China Securities News reported on March 21, 2014： Guangdong Hongtu Wuhan Die Casting Co., Ltd. （Wuhan Hongtu）, a wholly owned subsidiary of Guangdong Hongtu Technology （Holdings） Co., Ltd., held a groundbreaking ceremony recently. With the registered capital of 50 million Yuan, Wuhan Hongtu has a total land area of 100,000 square meters and a plant construction area of 72,000 square meters. It is expected to have a production capacity of about 30,000 tonnes of aluminum castings annually after it is put into production.