Al/stainless-invar composites with tailored anisotropy for thermal management in light weight electronic packaging
Al/stainless-invar composites with tailored anisotropy for thermal management in light weight electronic packaging
复制标题
DOI：
10.1016/j.matdes.2015.06.178
复制
发表时间：
2015-11
影响因子：
8.4
通讯作者：
S. Ryelandt;A. Mertens;F. Delannay
中科院分区：
文献类型：
--
作者：
S. Ryelandt;A. Mertens;F. Delannay
其中低CTE相具有蜂窝形状的复合板被预期为电子封装中的基板呈现最佳的热膨胀和热导率的各向异性。通过选择用于低CTE相的因瓦合金来探索该设计。为了在挤压铸造过程中形成钝化层以防止与液态Al反应，蜂窝由通常称为“不锈钢-因瓦”的富铬合金制成。含20体积%的复合板和38体积%使用具有相同厚度与单元边长比的蜂窝体来加工不锈钢因瓦合金。实验CTE值显着低于三种不同的热弹性模型的预测。应变滞后的非常有限的幅度排除了在基体中的全局塑性屈服的发生。看来，由于低CTE相的高连续性，实验CTE的低值是由局部塑性流动引起的空隙闭合和打开造成的。38%的蜂窝体体积分数对于将平均CTE降低到适合于包装应用的水平是必要的。横向热导率与密度之比则相当于最佳Al/SiC复合材料的性能的大约一半。
Composite plates in which the low CTE phase has the shape of a honeycomb are anticipated to present optimum anisotropy of thermal expansion and thermal conductivity for baseplates in electronic packaging. This design is explored by choosing an invar alloy for the low CTE phase. In order to allow the formation of a passivation layer protecting from reaction with liquid Al during squeeze casting, the honeycomb is made of the Cr-rich alloy commonly called “stainless-invar”. Composite plates containing 20 vol.% and 38 vol.% stainless invar were processed using honeycombs with the same thickness over cell side ratio. Experimental CTE values are significantly lower than the predictions of three different thermo-elastic models. The very limited amplitude of the strain hysteresis precludes the occurrence of global plastic yielding in the matrix. It appears that, owing to the high contiguity of the low CTE phase, the low value of the experimental CTE results from void closing and opening by localised plastic flow. A honeycomb volume fraction of 38% is necessary for bringing the average CTE down to the level suitable for packaging applications. The ratio of transverse thermal conductivity to density then amounts to about half of the performance of the best Al/SiC composites.