共查询到19条相似文献,搜索用时 93 毫秒
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一种环保型电子封装用复合材料 总被引:1,自引:0,他引:1
采用挤压铸造专利技术制备了体积分数为65%高纯Si的环保型Sip/Al-Si20复合材料。试验结果表明:复合材料的铸态组织均匀、致密,没有明显的颗粒团聚和偏聚,也不存在微小的孔洞和明显的缺陷;Sip/Al-Si20是一种轻质(密度为2.4g/cm3)、低膨胀系数(7.77×10-6℃-1)、高热导率[156.34W/(m·℃)]复合材料,电导率为4.08MS/m,具有较高的比模量和比强度;Sip/Al-Si20复合材料可以进行镀Ni和封装焊接。 相似文献
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电子封装用金属基复合材料的研究现状 总被引:24,自引:0,他引:24
微电子技术的飞速发展也同时推动了新型封装材料的研究和开发。本文综述了电子封装用金属基复合材料的研究和发展状况,并以A1/SiCp为重点,分析对比了目前国内外的差距,提出了其未来的发展趋势及方向。 相似文献
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高体积分数电子封装用铝基复合材料性能研究 总被引:2,自引:0,他引:2
高体积分数颗粒增强铝基复合材料由于其具有高导热、热膨胀系数可以调整、低密度和低成本而在电子封装领域有着广泛的应用。文章采用挤压铸造法制备了Sip/Al复合材料,金相观察表明,复合材料的铸态组织致密,颗粒分布均匀,没有微小的孔洞和明显的缺陷;复合材料20℃-100℃的平均线膨胀系数为7.6~8.1×10-6·℃-1,导热率大于100W(m·℃)-1,同时Sip/Al复合材料具有较低的密度(2.4g·cm-3)、较高的比强度、比模量采用化学镀的方法,复合材料表面的镀 Ni层连续、均匀,以其作为底座的二极管满足器件可靠性测试要求。 相似文献
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Maor S. Shapira F. Shmilovici A. 《Electronics Packaging Manufacturing, IEEE Transactions on》2003,26(1):31-36
The last stage of any type of manufacturing industry, is the packaging for shipment. Manufactured items can come in multiple sizes, weights, and sensitivity to shipment hazards. Yet, the number of standard packaging methods, such as cardboard box sizes or plastic-wrapping bags is limited. Thus, before the shipping of any type of products to their final destination, suitable packages have to be selected. Failure to select the best package for the shipment, may induce additional shipment costs or the possibility of shipping damage. Motorola Arad is the manufacturer of a large variety of electronic systems for Motorola, Inc. It has to handle many types of shipment orders each week. A prototype expert system was implemented, which uses fuzzy rules and fuzzy variables to recommend the best packaging method for each item and each shipment. Utilizing the fuzzy expert system resulted in significant decrease in the packaging volumes and packaging costs. 相似文献
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研究了粉末注射成型技术生产Invar合金电子封装零件的工艺。设计一种新型蜡基多聚合物组元粘结剂,其组成:PW,PEG,LDPE,PP,SA的质量分数分别为50%,20%,15%,10%,5%。并依其差热分析结果制定了合理的脱脂工艺。在1350℃氢气烧结时,可制备出性能优良的PIM Invar合金电子封装零件,其致密度、抗拉强度、30~300℃温度内的平均热膨胀系数α30~300℃分别为98.5%、420MPa、4.5×10–6℃–1,其漏气率小于1.4×10–9Pa·m3·s–1。 相似文献
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Domination of the electromagnetic spectrum is a crucial component of the 21st century warfare. In the harsh electromagnetic environment of the modern battlefield, it is of the utmost importance to deny the opposing force the opportunity to attack or exploit the detection/interception of friendly communications assets through the deployment of electronic protection (EP) measures in order to attain low probability of detection (LPD), low probability of interception (LPI) and anti-jam (A/J). Given that directional antennas are a suitable means to achieve both extended range and LPD/LPI, this paper proposes mechanisms to optimize the trade-off between these capabilities, minimizing the number of hops and end-to-end delay when routing packets in a multi-hop ad-hoc network, while taking into account stealth requirements. The novel scheme is based on a variant of Fisheye State Routing, coupled with a power control algorithm to guarantee a LPD/LPI beyond the zone covered by the omni-directional radiation footprint of the network. The performance of the proposed scheme is evaluated through computer simulation. 相似文献
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One of the major challenges faced by electronic publishing is that of preventing individuals from easily copying and illegally distributing electronic documents. The authors explore the use of cryptographic protocols to discourage the distribution of illicit electronic copies, and propose an architecture and two separate strategies for making electronic document distribution secure 相似文献
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目前OTN是业务承载的主要方式,为提高网络的安全性,网络中采用OLP/OMSP、ODUk SNCP 1+1、OCP 1+1等多种保护措施.同时,业务层自身也有保护,多重保护嵌套后,如何实现各种保护的协调,保证故障时不会出现多保护同时倒换,避免倒换震荡和业务闪断是需要在网络开通时需要关注的问题.本文通过分析不同保护方式倒... 相似文献
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通过对复杂电磁环境的构成要素多样性及其对装备影响机理差异性的分析,从电磁信号的时域、频域、功率、调制和极化参数入手,提出了一种基于干信比的电子干扰信号度量方法。建立了基于调制匹配系数、极化匹配系数和相对功率强度的度量指标,实现了电磁环境特征、装备技术特点以及电磁环境度量结果的一致性。最后通过仿真计算验证了度量方法的可行性和合理性。 相似文献
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Brassil J.T. Low S. Maxemchuk N.F. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1999,87(7):1181-1196
Each copy of a text document can be made different in a nearly invisible way by repositioning or modifying the appearance of different elements of text, i.e., lines, words, or characters. A unique copy can be registered with its recipient, so that subsequent unauthorized copies that are retrieved can be traced back to the original owner. In this paper we describe and compare several mechanisms for marking documents and several other mechanisms for decoding the marks after documents have been subjected to common types of distortion. The marks are intended to protect documents of limited value that are owned by individuals who would rather possess a legal than an illegal copy if they can be distinguished. We describe attacks that remove the marks and countermeasures to those attacks. An architecture is described for distributing a large number of copies without burdening the publisher with creating and transmitting the unique documents. The architecture also allows the publisher to determine the identity of a recipient who has illegally redistributed the document, without compromising the privacy of individuals who are not operating illegally. Two experimental systems are described. One was used to distribute an issue of the IEEE Journal on Selected Areas in Communications, and the second was used to mark copies of company private memoranda 相似文献