用扫描热显微镜研究材料表面微区热导分布

从集总参数模型出发,初步分析了热敏电阻型热探针的热传导机制和热物性测量机理,说明了扫描热探针的信号与样品表面温度、样品与探针间的热阻以及样品热导率等因素有关。在不同的工作条件下,可分别用以进行表面的温度分布和微区热导分布等热参数的测量。选定Ｓｉ－ＳｉＯ２标准样品,定性地讨论了表面形貌和样品热导率对测量结果的影响。把扫描热显微镜用于复合材料研究,得到的热像图提供了微区热导分布的信息。     

电子封装用环氧树脂基复合材料的优化

研究了593固化剂不同用量加入电子封装用环氧树脂E-51中的效果,以及在E-51,Al2O3复合材料中硅烷偶联剂不同用量的效果,结果显示:593固化剂与环氧树脂质量比为1:4时,复合材料的致密度高,气孔少,成型效果好;当硅烷偶联剂KH-560质量分数为8%时,复合材料的热导率达到0.75 W/(m·K).     

高导热金刚石/玻璃复合材料的制备和性能研究

首先对金刚石颗粒进行化学镀Cu,并控制氧化,从而在金刚石颗粒表面获得Cu-Cu2O复合结构。然后,在800℃无压烧结制备了金刚石/玻璃复合材料,观察了其表面和界面形貌,并测定了其相对密度和热导率。结果表明,通过对镀Cu金刚石的控制氧化,明显改善了玻璃对金刚石颗粒表面的润湿性,避免了玻璃对金刚石颗粒表面的侵蚀,提高了复合材料的热导率;复合材料的热导率随金刚石含量的增加而增加,当金刚石质量分数为70%时,热导率最高达到了14.420W/(m·K)。     

电子封装热管理的热电冷却技术研究进展

电子封装器件中芯片的散热问题一直是制约其发展的瓶颈。综述了芯片的产热特征、散热需求与散热方式。对热电冷却(TEC)技术在芯片散热系统上的应用进行分析,指出了其不足之处与特有的优势。对热电冷却技术在芯片热管理方面应用研究的现状与进展进行了总结评述。     

Improving thermal conductivity of polymer composites in embedded LEDs systems

Polymer embedding of LEDs increases safety and waterproof levels in LED based lighting systems. The embedding allows for mechanical flexibility of these systems. The increase of polymer thermal conductivity has been a research challenge for decades. Here, we suggest materials for enhancing thermal conductivity in polymer embedded LED systems. We demonstrate that thermally conductive fillers into the polymer matrix to form a composite improved heat transfer from the LEDs to the environment. Non metallic boron nitride with a high intrinsic thermal conductivity is a good candidate. Thermal conductivity of basic polymer PDMS with various filler size and polymer ratios is reported here. Here, an in situ measurement tool to fast evaluate the quality of the composites in LED applications is demonstrated. Future work will focus on further increasing the thermal conductivity of the composites by using different mixtures.     

粉末冶金法制备AlSiC电子封装材料及性能

采用粉末冶金法制备了一定粒径分布的SiC颗粒体积分数不同的AlSiC电子封装复合材料。实验结果表明:材料微观组织致密,颗粒分布均匀。复合材料的平均热膨胀系数、热导率和弯曲强度都随SiC含量的增加而降低,抗弯断口以脆性断裂为主要断裂模式。     

高导热聚合物基复合封装材料及其应用

微电子封装密度的提高对传统环氧塑封料的导热性能提出了更高的要求,将高导热的陶瓷颗粒/纤维材料添加到聚合物塑封材料中可获得导热性能好的复合型电子封装材料。文章结合高导热环氧塑封材料的研究工作,评述了高热导聚合物基复合封装材料的材料体系、性能特点和在微电子封装中的应用情况。分析讨论了影响聚合物基复合电子封装材料导热性能和介电性能的因素,提出了进一步提高聚合物基复合电子封装材料导热性能的途径。     

21世纪我国电子封装行业的发展机遇与挑战

分析了国内外电子封装技术的发展历史和趋势。结合 2 1世纪初信息化和经济全球化的时代特征 ,讨论了目前我国电子封装行业所面临的计算机市场高速增长、移动通信产品国产化及外商投资三个良好机遇 ,指出了我国电子封装行业将要面临的激烈的国际市场竞争和原材料国产化的挑战。     

Thermal conductivity of bulk ZnO after different thermal treatments

Thermal conductivities (κ) of melt-grown bulk ZnO samples thermally treated under different conditions were measured using scanning thermal microscopy. Samples annealed in air at 1050°C for 3 h and treated with N-plasma at 750°C for 1 min. exhibited κ=1.35±0.08 W/cm-K and κ=1.47±0.08 W/cm-K, respectively. These are the highest values reported for ZnO. Atomic force microscopy (AFM) and conductive-AFM measurements revealed that surface carrier concentration as well as surface morphology affected the thermal conductivity.     

Anisotropic conductive adhesives with enhanced thermal conductivity for flip chip applications

This paper presents the development of new anisotropic conductive adhesives (ACAs) with enhanced thermal conductivity for improved reliability of adhesive flip chip assembly under high current density condition. As the bump size in the flip chip assembly is reduced, the current density through the bump also increases. This increased current density causes new failure mechanisms, such as interface degradation due to intermetallic compound formation and adhesive swelling resulting from high current stressing. This process is found especially in high current density interconnection in which the high junction temperature enhances such failure mechanisms. Therefore, it is necessary for the ACA to become a thermal transfer medium that allows the board to act as a new heat sink for the flip chip package and improve the lifetime of the ACA flip chip joint. We developed the thermally conductive ACA of 0.63 W/m·K thermal conductivity by using a formulation incorporating the 5-μm Ni-filled and 0.2-μm SiC-filled epoxy-based binder system. The current carrying capability and the electrical reliability under the current stressing condition for the thermally conductive ACA flip chip joints were improved in comparison to conventional ACA. This improvement was attributed to the effective heat dissipation from Au stud bumps/ACA/PCB pad structure by the thermally conductive ACA.