纳米材料在电子封装互连及散热方面的研究

发布时间：2018-02-26 10:54

本文关键词： 电子封装纳米材料互连散热　出处：《上海大学》2015年博士论文　论文类型：学位论文

【摘要】：电子封装可以为脆弱的芯片提供有效的保护并提供导电导热通路,因此是电子产品中一个重要的组成部分。电子封装所用的材料和结构对日后电子产品的成本、尺寸和性能有着巨大的影响。近些年,电子产品的小型化与多功能化发展趋势明显。这一趋势极大地增加了电子产品的封装密度与功率,对封装的材料与结构提出了更高的要求。因此,电子封装新材料与新结构的开发工作的开展迫在眉睫。基于上述情况,本论文尝试了使用纳米材料来解决高密度电子封装中的互连与散热问题。在互连方面,使用热化学气相沉积(TCVD)方法生长的竖直排列的纳米碳管(VACNT)被用作了硅通孔的填充材料。与此同时,使用等离子体增强化学气相沉积方法(PECVD)制备的竖直排列的纳米碳纤维(VACNF)即被用作了芯片凸点材料,也被用作了焊点的强化材料。由于碳基材料良好的稳定性,许多在传统互连材料中容易出现的问题,例如电迁移和晶粒粗化,可以得到明显的改观。除了使用碳基材料,合金及半导体纳米材料也被应用在了互连材料之中。研究表明,分布在焊点中的纳米颗粒可以有效的钉扎位错并限制裂纹的生长。因此,在本论文中,Sn-3.0Ag-0.5Cu(SAC305)纳米颗粒以及Bi2Te3纳米颗粒被分别加入了Sn-58Bi焊膏和SAC305焊膏中以提高两种焊膏的强度和热机疲劳抗性。在试验中我们发现少量的纳米颗粒确实可以提高焊点的强度,但是当过多的纳米颗粒被加入焊膏体系中,焊点的强度会再度由强变弱。这种现象可能是由焊点中严重的纳米颗粒团聚或者大量的孔洞引起的。另外,我们还发现缩小焊点中纳米材料与基体材料在密度和热膨胀系数(CTE)方面的差异,可以减小纳米材料在回流焊接过程中的流失。在散热方面,我们开发了一种由聚酰亚胺(PI)纤维网格强化的In金属界面散热材料(Nano-TIM)。除此之外,一种由Ag和Bi2Te3纳米颗粒组成的纳米结构的热电(TE)材料也被开发出来作为一种用于芯片上热点的主动散热解决方案。根据所得实验结果,PI纤维网格可以提高In金属界面散热材料的机械性能且不失其自身较高的散热性能。这一强化效果得益于表面镀Ag的PI纤维网格对In金属内部裂纹扩展的限制作用。本论文中所涉及的纳米结构热电材料具有良好的导电能力以及极低的热导率。这两点是高性能热电材料的必备条件。良好的电导率是通过加入适量的Ag纳米颗粒实现的,极低的热导率则是通过纳米结构中微小界面对声子的散射实现的。
[Abstract]:Electronic packaging is an important component of electronic products because it can provide effective protection for vulnerable chips and provide conductive thermal access. The materials and structures used in electronic packaging will cost future electronic products. Size and performance have a great influence. In recent years, the trend of miniaturization and multifunction of electronic products is obvious. This trend has greatly increased the packaging density and power of electronic products. Therefore, the development of new materials and structures for electronic packaging is urgent. In this paper, we try to use nanomaterials to solve the problem of interconnection and heat dissipation in high-density electronic packaging. Vertically arranged carbon nanotubes (VACNTs) grown by thermochemical vapor deposition (TCVD) method are used as filling materials for silicon through pores. The vertical arrangement of carbon nanofibers (VACNF) prepared by plasma enhanced chemical vapor deposition (PECVD) is used either as a chip bump material or as a solder joint strengthening material. Many problems that may arise easily in conventional interconnection materials, such as electromigration and grain coarsening, can be significantly improved. In addition to the use of carbon-based materials, alloys and semiconductor nanomaterials are also used in interconnect materials. Nanocrystalline particles distributed in solder joints can effectively pinpoint dislocations and limit the growth of cracks. In this paper, Sn-3.0 Ag-0.5CuSSAC305) nanoparticles and Bi2Te3 nanoparticles were added to Sn-58Bi solder paste and SAC305 solder paste respectively to improve the strength and thermal fatigue resistance of the two kinds of solder paste. However, when too many nanoparticles are added to the solder paste system, the strength of the solder joint becomes weaker again. This phenomenon may be caused by the serious agglomeration of nanoparticles in the solder joint or a large number of holes. We also found that reducing the difference in density and thermal expansion coefficient (CTE) between nanomaterials and matrix materials in solder joints can reduce the loss of nanomaterials during reflux welding. We have developed an in metal interface heat dissipation material, Nano-TIMO, which is reinforced by polyimide (Pi) fiber mesh. A thermoelectric nanostructure composed of Ag and Bi2Te3 nanoparticles has also been developed as an active heat dissipation solution for hot spots on chips. According to the experimental results, Pi fiber mesh can improve in metal. The mechanical properties of interfacial heat dissipation materials without losing their own high heat dissipation properties. This strengthening effect is due to the limiting effect of Ag plated Pi fiber mesh on the internal crack growth of in metal. Structural thermoelectric materials have good conductivity and very low thermal conductivity. These two conditions are necessary for high performance thermoelectric materials. Good conductivity is achieved by adding appropriate amount of Ag nanoparticles. The very low thermal conductivity is achieved by scattering phonons from tiny interfaces in nanostructures.
【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1

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