SBIR Phase II: Multimodal High-Conductivity Filler for Epoxy Molding Compounds

该小型企业创新研究第二阶段项目将专注于开发更高效的半导体封装材料，这是电子行业的关键挑战之一，其中集成电路的功率增加和尺寸减小带来了散热挑战。大多数用于封装半导体的环氧模塑化合物含有熔融石英（55-70%体积），以保持相容的热膨胀系数并赋予防潮性。然而，复合化合物的热导率非常低（1 W/mK）。环氧树脂模塑料的低导热性增加了工作温度，这反过来又降低了微处理器的可靠性和处理速度。随着半导体时钟速度的不断提高和芯片尺寸的不断减小，对更高导热性的模塑材料的需求已变得非常必要。在该项目的第一阶段，高导电性金刚石粉末的多模态分布进行了优化，以获得环氧树脂模塑料中的高填充密度（超过72%体积）。由此产生的金刚石/环氧树脂复合材料的热导率比传统的二氧化硅填充的环氧树脂高近8倍，比环氧树脂基体高近30倍。二氧化硅和金刚石填料的热膨胀同样低，因此可以更好地匹配硅。在该第二阶段项目中，通过优化具有金刚石填料的环氧树脂/硬化剂系统来实现显著更高的热导率，以改善粘合，从而改善传热机制。金刚石填料将被用作市售二氧化硅填料的直接替代品，几乎不需要或不需要对现有设备或工艺进行修改。金刚石/环氧树脂模塑料将有效地充当散热器。金刚石填充物将允许更高的开关速度，更薄的氧化物栅极和增加的电子可靠性。项目团队将与环氧树脂模塑料（EMC）制造商合作，在第二阶段结束时将金刚石填料引入商业市场。该EMC技术的商业市场包括高性能航空航天、汽车和微电子封装应用，其中封装材料的散热超过了材料成本的增加。由金刚石填料提供的增加的导热性将通过提高计算速度和硬件可靠性而使商业和科学界受益。研究表明，散热和相关的热问题是决定电子设备效率和可靠性的最关键因素。在科学和教育价值方面，EMC采用优化的金刚石填料将表现出可获得的最大热导率，并作为复合材料热导率的上限基准。

This Small Business Innovation Research Phase II project will focus on developing more efficient semiconductor packaging materials, which is one of the key challenges of the electronics industry where increasing power and reduced size of integrated circuits is creating heat dissipation challenges. Most epoxy molding compounds used toencapsulate semiconductors contain fused silica (55-70% by volume) to maintain acompatible thermal expansion coefficient and impart moisture resistance. However, theresulting thermal conductivities of the composite compounds are very low (1 W/mK). Thelow thermal conductivity of the epoxy molding compound increases the operating temperatures, which in turn decreases the reliability and processing speed of microprocessors. As semiconductor clock speeds continue to increase and chip sizes decrease, the need for higher thermally conductive molding materials has become a stark necessity. In Phase I of this project multi-modal distributions of high-conductivity diamond powder where optimized to obtain high packing densities (over 72% by volume) in epoxy molding compounds. The resulting thermal conductivities of diamond/epoxy composites were almost 8 times higher than conventional silica-filled epoxies and almost 30 times higher than the epoxy matrix. The thermal expansions of silica and diamond filler are similarly low, thus allowing better matching to silicon. In this Phase II project significantly higher thermal conductivities are to be achieved by optimizing the epoxy/hardener system with the diamond filler to improve bonding and thereby improving the heat transfer mechanism. The diamond filler will be used as a direct substitute for commercially available silica filler, requiring little or no modification of existing equipment or processing. The diamond/epoxy molding compound will effectively act as a heat-spreader. The diamond filler will allow higher switching speeds, thinner oxide gates and increased reliability ofelectronics. The project team will work with an epoxy molding compound (EMC) manufacturer to introduce the diamond filler into the commercial market towards the end of Phase II.Commercial markets for this EMC technology include high-performance aerospace, automobile and microelectronic packaging applications, where heat dissipation from the packaging material outweighs the increased material cost. The increased thermal conductivity offered by the diamond filler will benefit the business and scientific community by increasing computing speed and hardware reliability. Studies indicate that heat dissipation and associated thermal problems are the most critical factors in determining the efficiency and reliability of electronic devices. In terms of scientific and educational value, EMC's incorporating the optimized diamond filler will exhibit the maximum thermal conductivity obtainable and serve as the upper-limit benchmark in thermal conductivity for the composite material.