Wet-chemical porosification of LTCC substrates: Dissolution mechanism and mechanical properties
Wet-chemical porosification of LTCC substrates: Dissolution mechanism and mechanical properties
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DOI：
10.1016/j.micromeso.2019.109593
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发表时间：
2019-11-01
影响因子：
5.2
通讯作者：
Schmid, Ulrich
中科院分区：
文献类型：
--
作者：
Hajian, Ali;Brehl, Martin;Schmid, Ulrich
低温共烧陶瓷（LTCC）技术已成功地应用于微电子、汽车和电信领域。然而，它们通常较高的介电常数对于在高频下工作的微机械设备是不利的。为了克服这个缺点，我们已经建立了一个湿化学蚀刻过程作为一个有效的方法，可以应用到LTCC基板在其作为烧制状态，并允许在感兴趣的区域的局部介电常数降低。了解蚀刻机制对于选择适当的蚀刻条件以控制多孔化程度是必不可少的。因此，在目前的工作中，我们报告了一种有效的方法来实现定制的多孔化LTCC基板。不同的表征技术，如扫描和透射电子显微镜，能量色散X-射线光谱，X-射线衍射分析，和拉曼光谱被用于调查的形态和化学成分的基板，从而研究蚀刻机制。此外，在高达550摄氏度的温度下使用动态力学分析，研究了湿化学蚀刻后LTCC基板的刚度行为，并且即使在高达550摄氏度的高温下操作，也获得了这种改性模块的适用性的有希望的结果。最后，提出了一个实际的机械性能和相对的多孔化深度之间的相关性，这是独立的蚀刻条件和基板厚度，是有价值的优化适当的多孔化深度，以确保所需的机械性能。
Low temperature co-fired ceramics (LTCC) technology has been successfully used in microelectronics, automotive, and telecommunication applications. However, their generally high permittivity is unfavorable for micromachined devices operated at high frequencies. To overcome this drawback, we have established a wet-chemical etching process as an effective approach which can be applied to LTCC substrates in their as-fired state and allows for a local permittivity reduction in regions of interest. Understanding the etching mechanism is essential for the selection of appropriate etching conditions to control the degree of porosification. Therefore, in the present work, we report on an effective approach to achieve a tailored porosification of LTCC substrates. Different characterization techniques such as scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and Raman Spectroscopy were used for investigation of the morphology and chemical composition of the substrates and thereby studying the etching mechanism. Furthermore, using dynamic-mechanical analysis at temperatures up to 550 degrees C, the stiffness behavior of the LTCC substrates after wet-chemical etching was investigated, and promising results for the applicability of such modified modules were obtained, even when operated at elevated temperatures up to 550 degrees C. Finally, a practical correlation between the mechanical properties and the relative porosification depth is presented, which is independent of etching conditions and the substrate thickness, and is valuable for optimization of the suitable depth of porosification for securing the desired mechanical properties.