电子封装用高硅铝合金热膨胀性能的研究

采用雾化喷粉与真空包套热挤压工艺制备了高硅铝合金电子封装材料,测定了合金在100～400℃间的热膨胀系数值,并运用理论模型对该温度区间的热膨胀系数进行了计算,分析了高硅铝合金材料热膨胀性能的影响因素.结果表明:Si相作为增强体能显著改善Al-Si合金的微观组织与热膨胀性能,430℃热挤压下的高硅铝合金材料在100～400℃之间的热膨胀系数平均值与Turner模型很接近.     

喷射成形铝硅合金电子封装梯度材料的研究进展

高硅铝合金电子封装材料以其良好的热物理性能与力学性能,越来越受到材料和电子封装行业研究者的重视,但是其焊接性能与机械性能不理想。铝硅合金梯度板材可解决电子封装材料低膨胀与高机械性能的矛盾,其高硅端热膨胀系数低,导热好,适于裸集成电路;低硅端机械性能高,可焊接,便于精加工和封装,是未来武器装备高集成电路封装构件重要的备选材料。针对这类材料的制备问题,提出了双金属一步式喷射成形技术的概念,并对喷射工艺参数进行了初步的探索研究。2个沉积器的间距可以影响复合板材的外形轮廓与内部硅成分的梯度分布,模拟结果显示间距大于等于40 mm时,出现台阶而且成分变化有突变。     

硅含量对高硅铝合金材料组织及性能的影响

针对航空航天电子封装用轻质高硅铝合金材料,采用空气雾化水冷与真空包套热挤压工艺相结合的方法,制备了Al-30Si和Al-40Si高硅铝合金,并利用金相显微镜、万能电子拉伸机、差热分析仪、TR-2热物性测试仪等设备系统测试和分析了该材料的显微组织、力学和热物理性能.结果表明:随着合金中硅含量的增加,经热挤压后的硅相尺寸相对要粗大一些;材料的热导率呈下降趋势,热导性能下降的幅度会随Si含量的增加而加大;热膨胀系数下降;材料的抗拉强度下降.     

不同制备工艺对高硅铝合金组织及力学性能的影响

针对航空航天电子封装用轻质高硅铝合金材料,采用铸轧工艺、喷射沉积工艺和粉末包套热挤压工艺制备了硅含量高达35%的高硅铝合金,利用金相显微镜、万能电子拉伸机、SEM对3种不同工艺所制备材料的微观组织、力学性能及断口进行了检测分析.结果表明:在含硅量相差不大时,粉末包套热挤压工艺成型材料的硅相细小,可达到2～10μm,且分布弥散均匀,抗拉强度达到174MPa,比铸轧工艺成型材料的强度提高了86.1%,比喷射沉积工艺成材料的强度提高了57.2%.     

封装用硅铝复合材料研制成功

<正>近日,由北京北科徳瑞冶金工程技术有限公司和北京科技大学共同承担的课题"封装用硅铝复合材料研制"顺利通过北京市科委组织的专家验收。高硅铝复合材料具有轻质、低膨胀、高导热等优异性能,是目前大功率高密度电子器件封装主流材料,在航空航天电子装备领域市场需求旺盛。目前制备高硅铝复合材料的喷射     

挤压温度对高硅铝合金材料力学性能的影响

针对航空航天电子封装用轻质高硅铝合金材料,采用空气雾化水冷与真空包套热挤压工艺相结合的方法,制备了Al-30Si和Al-40Si过共晶高硅铝合金材料,并通过金相显微镜观察了材料的微观组织,测定了合金材料的抗拉强度以及延伸率,对拉伸试样的断口进行了扫描.探讨了挤压温度对材料组织、强度、延伸率及断裂行为的影响.结果表明:利用粉末冶金热挤压技术所制备的高硅铝合金材料,其硅相细小,当挤压温度为370℃时,其硅相大小为2～10μm,且分布均匀弥散;硅相尺寸随着挤压温度的升高而长大;抗拉强度随挤压温度的升高而降低,Al-30Si经370℃挤压后,其室温抗拉强度为239MPa,而550℃为206MPa;延伸率随挤压温度的升高而有所增加,但不很敏感;随挤压温度的升高,材料的断裂方式由单纯的韧性断裂逐渐向韧性与脆性共存的混合断裂方式转变.     

应用于电子封装的新型硅铝合金的研究与开发

较详细地论述了新型硅铝（Al-70%Si)合金的制备,机械加工及焊接性能,物理性能,应用Osprey喷射沉积成形技术开发出的新型硅铝（Al-70%Si)合金,晶粒细小,微观结构各向同性,可用一般刀具机加工,机加工后的表面可以镀镍,铜,银和金,电镀层与基体结合牢固,在450度不会开裂,硅铝合金的热传导率及热膨胀系数与半导体的相近,并有其它优良性能,与传统的电子封装材料相比有更好的应用价值。     

电子封装基片材料研究进展

阐述了电子封装领域对基片材料的基本要求,分析了电子封装用陶瓷,环氧玻璃,金钢石,金属及金属基合材料的性能特点,论述了电子封装基本的研究现状,并指出了发展方向。     

电子封装用聚苯硫醚高性能复合材料的研制

微电子工业的快速发展迫切需要性能更为优异的封装材料.采用聚苯硫醚复合材料作为电子封装材料,具有使用温度高、热膨胀系数低、介电损耗低、电绝缘性能好等优异的性能,应用于现代微电子领域的前景良好.本文用国产商品PPS树脂经纯化处理后,与其它材料复合,成功制备出了聚苯硫醚高性能电子封装材料,制备的PPS电子封装材料具有低吸水性、低热膨胀系数、高强度以及优异的介电性能等综合性能,优于目前常用的环氧类电子封装材料.     

快速凝固/粉末冶金(RS/PM)高硅铝合金材料的研究

采用冷压 +热挤压工艺制备快速凝固高硅铝合金材料 ,并探讨了挤压温度、保温时间、挤压比等工艺参数对材料组织及性能的影响 .研究结果表明 ,与高硅铝合金铸造材料相比 ,本研究所制的材料硅相尺寸得到了显著细化 ,且分布更为均匀 ,材料的抗拉强度和延伸率有明显的提高 .采用光学金相显微镜、SEM、XRD等手段对快速凝固高硅铝合金粉末及大块材料的微观结构及相组织进行了深入研究 .     

Synthesis and characterisation of free standing,one­dimensional,Al–SiC based functionally gradient material

Abstract

In the present study, an aluminium–silicon carbide based functionally gradient material was successfully synthesised using a new technique termed here as gradient slurry disintegration and deposition process. The gradient of SiC was successfully established using this technique for 21 wt-%SiC. The results were confirmed using microstructural characterisation techniques, microhardness measurements, and wear rate determination. The results further revealed that an increase in the weight percentage of silicon carbide particulates along the deposition direction lead to a concurrent increase in porosity, degree of clustering, and microhardness while the nature of silicon carbide/aluminium interfacial integrity remained the same. The results of wear rate determination indicated that a difference of ～9.53 vol.-%SiC on the opposite faces of the functionally gradient material led to the wear resistance increasing to ～31.5× that of the high aluminium end. An attempt is made to interrelate the processing methodology, microstructure, microhardness, and wear rate results obtained in the present study.     

用于微电子机械系统封装的体硅键合技术和薄膜密封技术

对静电键合、体硅直接键合和界面层辅助键合等三种体硅键合技术，整片操作、局部操作和选择保护等三种密封技术，以及这些技术用于微电子机械系统的密封作了评述，强调在器件研究开始时应考虑封装问题，具体技术则应在保证器件功能和尽量减少芯片复杂性两者之间权衡决定。     

The effects of alloying material on regrowth-layer structure in silicon power devices

The effects on silicon regrowth-layer structure of pure aluminium are compared with those of aluminium-silicon alloy of eutectic composition when these are used as alloying material in joining silicon discs to metal contacts.Non-uniform dissolution of silicon by pure aluminium is prevalent, and the configuration of the regrowth and undissolved silicon surfaces shows dissolution in preferred crystallographic directions. Measurements of recesses in the surfaces show that penetration into the silicon to depths of the order of 100 m may occur during alloying. This is sufficient to penetrate diffused junctions resulting in the formation of local alloyed junctions of irregular shape with disastrous effects on the electrical characteristics of the device. Deep penetration is caused by a high solubility for silicon being suddenly presented locally when melting of the aluminium is initiated at points where conditions are most favourable.In contrast aluminium-silicon eutectic alloy does not dissolve further silicon immediately on melting, and deep local penetration can thereby be avoided.Measurements made on devices incorporating aluminium-silicon eutectic alloy show reductions in mean penetration depths of over 50%, and the elimination of those regrowth configurations that indicate dissolution in preferred directions.     

Beryllium metal matrix composites for aerospace and commercial applications

Abstract

There is a growing need in both aerospace and commercial markets for lighter weight, higher stiffness, higher thermal stability materials to solve the design engineers’ problems of reduced mass, higher access speeds, improved mechanical and thermal stability for today's advanced technology. To address those needs, Brush Wellman Inc. has developed, characterised, and put into high volume production a family of beryllium metal matrix composites. There are two classes of materials that have been developed to provide these engineering benefits to the designer in both the commercial and aerospace markets. The first family of materials is aluminium beryllium (AlBeMet, which is a registered tradename of Brush Wellman). This material is a metal matrix composite consisting of pure beryllium and aluminium, with 20–62 vol.-%Be and the remainder aluminium. The material is produced by both powder metallurgy and net shape technologies such as investment casting and semi-solid forming. The materials properties that make it attractive for the design engineer are a density that is 25% less than that of aluminium, a specific stiffness four times those of aluminium, titanium, steel, and magnesium, a higher dampening capacity than aluminium, and a coefficient of thermal expansion almost 50%lower than aluminium. The second family of materials is a beryllium–beryllium oxide metal matrix composite, which are called E materials. This material was developed to address the thermal management needs of the electronic packaging design engineer. The material properties that make this material attractive to the electronic packaging engineer are: a density 20–25% that of Kovar, Invar, and CuMoCu, and 30% less than Al–SiC; a thermal conductivity ranging from 210 to 240 W m^-1 K^-1and a tailorable coefficient of thermal expansion, ranging from 6×10^-6 to 8.7×10^-6 K^-1.     

Diamond-like carbon,a barrier coating for polymers used in packaging applications

Water and oxygen permeability measurements on two polymers, poly(ethylene terephthalate) and polypropylene, are presented as a function of diamond-like carbon coating thickness. Results show that reliable and reproducible coatings can be achieved on poly(ethylene terephthalate) such that levels of permeability are about 1 cc/m²/day for oxygen and 1.5 g/m²/day for water vapour, comparable to the levels for silicon oxides and aluminium coatings used in the packaging industry. The advantages conferred by diamond-like carbon over aluminium is primarily that of retaining optical transparency in the thickness of films used in this work (20 nm). The advantages of diamond-like carbon over silicon oxides is related to its intrinsic flexibility. Other advantages over other barrier films (e.g. polyvinylidine chloride) and coating technologies is the ability to recycle the used product. The permeability of diamond-like carbon-coated polypropylene to oxygen is in the range of 200 cc/m²/day, again comparable to results obtained with the other coatings. The optimum film thickness for poly(ethylene terephthalate) to minimize permeability was 20 nm. Atomic force microscopy revealed agglomerated structures (possibly graphitic) with the underlying substrate appearing smoother than the starting material. In comparison, polypropylene exhibited increased surface roughness under the same coating conditions.     

铝硅合金热疲劳过程的应力应变分析

对铝硅合金进行了热疲劳模拟实验和应力、应变分析。铝硅合金的导热系数高,高温弹性模量低,温度涨落过程产生的宏观热应力低于同一温度下合金的屈服应力和疲劳极限;而铝、硅热膨胀系数的差异将在铝硅相界等局部区域产生远大于宏观热应力的微观热应力,并因此萌生热疲劳裂纹。通过变质工艺改变硅相形态,可改善合金的抗热疲劳性能。     

AlSiC电子封装材料及构件研究进展

AlSiC电子封装材料及构件具有高热导率、低膨胀系数和低密度等优异性能,使封装结构具有功率密度高、芯片寿命长、可靠性高和质量轻等特点,应用范围从功率电子封装到高频电子封装.综述了国内外制备AlSiC电子封装材料及构件所涉及的预制件成形、液相浸渗铸造、力学性能、气密性、机械加工、表面处理和构件连接等方面的研究进展.     

Threshold creep behaviour of discontinuous aluminium and aluminium alloy matrix composites: An overview

Several sets of creep data for aluminium and aluminium alloy matrix composites reinforced by silicon carbide particulates, silicon carbide whiskers or alumina short fibres are analysed. It is shown that for this class of discontinuous composites the threshold creep behaviour is inherent. Applying the concept of threshold stress, the true stress exponent of minimum creep strain rate of approximately 5 follows from the analysis even when the matrix solid solution alloy exhibits Alloy Class creep behaviour, for which the value of 3 for the true stress exponent is typical. The creep strain rate in the discontinuous aluminium and aluminium alloy matrix composites is shown to be matrix lattice diffusion controlled. The usually observed high values of the apparent stress exponent of creep strain rate and the high values of the apparent activation energy of creep are then rationalized in terms of the threshold creep behaviour. However, the origin of the threshold stress decreasing with increasing temperature but not proportional to the shear modulus in creep of discontinuous aluminium and aluminium alloy matrix composites is still awaiting identification. The creep-strengthening effect of silicon carbide particulates, silicon carbide whiskers and alumina short fibres is shown to be significant, although the particulates, whiskers and short fibres do not represent effective obstacles to dislocation motion.     

A sub-atmospheric chemical vapor deposition process for deposition of oxide liner in high aspect ratio through silicon vias

The formation of a Through Silicon Via (TSV) includes a deep Si trench etching and the formation of an insulating layer along the high-aspect-ratio trench and the filling of a conductive material into the via hole. The isolation of the filling conductor from the silicon substrate becomes more important for higher frequencies due to the high coupling of the signal to the silicon. The importance of the oxide thickness on the via wall isolation can be verified using electromagnetic field simulators. To satisfy the needs on the Silicon dioxide deposition, a sub-atmospheric chemical vapor deposition (SA-CVD) process has been developed to deposit an isolation oxide to the walls of deep silicon trenches. The technique provides excellent step coverage of the 100 microm depth silicon trenches with the high aspect ratio of 20 and more. The developed technique allows covering the deep silicon trenches by oxide and makes the high isolation of TSVs from silicon substrate feasible which is the key factor for the performance of TSVs for mm-wave 3D packaging.     

Application of plasma etching techniques to metal-oxide-semiconductor (MOS) processing

Compared with wet etching techniques for the fabrication of MOS integrated circuit (IC) devices, plasma etching can offer better line fidelity (through reduced undercutting of the resist mask), greater tolerance towards adhesion of the resist layer and, in some cases, process simplification. However, because of the small but finite etch rates of the masking resist and the substrate material, careful consideration must be given to the minimum thickness of resist used and to the maximum amount of over-etching that can be tolerated. These factors are illustrated by considering the etching of silicon nitride, aluminium and silicon dioxide layers. It is shown that the plasma etching of silicon nitride can result in process simplification, whilst the plasma etching of aluminium and aluminium-silicon layers gives excellent edge definition and is fully compatible with conventional IC processing, provided due consideration is given to the thickness and character of the masking resist layer. The plasma etching of oxide layers with adequate selectivity can now be achieved and is particularly useful for the high resolution etching of windows in phosphorous-doped oxide layers.