Key Technologies and materials for new generation ferrite-metal composite multilayer power inductive devices

由于移动的通信的进步，不仅电子设备变得更小，而且它们的功能也不断升级。分立元件不能完全满足小型化的要求。此外，便携式设备继续朝着低轮廓和多功能性发展，这导致工作电压的多样化。便携式设备通常由电池供电，并且DC-DC转换器用于转换电池能量以向微处理器和集成电路供电。便携式电子设备要求紧凑，因此用于转换器的空间非常有限。因此，将单个组件集成到模块中以减小DC-DC转换器的尺寸并增加其功率密度的需求正在增加。为了实现这一目标，需要改进的电感组件。新概念包括铁氧体金属复合电感器的制造。陶瓷多层膜技术和低温陶瓷共烧（LTCC）技术是制造复杂多层模块中使用的平面无源器件的常用现代技术。LTCC技术是一种很有前途的无源制造和三维集成技术。铁氧体带和浆料以及低k电容器带用于制造平面嵌入式无源器件，并且它们可以容易地集成到LTCC介质基板中以形成复杂的模块。在此基础上，我们致力于镍（铜）锌铁氧体-金属复合多层电感的材料和工艺研究。研究了在还原气氛下烧结的Ni（Cu）Zn铁氧体的电磁性能;研究了Ni（Cu）Zn铁氧体与基体金属电极（铜）的共烧工艺;研究了Ni（Cu）Zn铁氧体和FeSiCr合金带在还原气氛下的加压约束烧结工艺。这包括研究铁氧体材料在低氧分压条件下的稳定性，以及在低温（900°C）和低pO 2下烧结的这些铁氧体材料的组成、烧结行为、微观结构、阳离子分布和功能特性之间的相关性。本项目由德国耶拿应用科学大学JörgTöpfer教授和台湾国立成功大学Hsing-I Hsiang教授合作，利用多层陶瓷加工和低压辅助约束烧结技术，将具有上级直流偏置叠加特性的Ni（Cu）Zn功率铁氧体与金属元件集成。德国团队将专注于固态化学和还原条件下铁氧体烧结的研究，而台湾团队则专注于金属合金成分及其在多层工艺中的应用。

Due to the advances in mobile communications, not only the electronic devices are getting smaller, but also their function is upgraded continuously. Discrete components cannot completely meet the requirements of miniaturization. Moreover, portable devices continue to develop toward low-profile and multi-functionality, which results in the diversification of operating voltages. Portable devices are often powered by batteries and DC-DC converters are used to convert battery energy to supply power for microprocessors and integrated circuits. Portable electronic devices are required to be compact and, hence, space for converters is very limited. Therefore, the demand for integrating individual components into modules to reduce the size and increase the power density of DC-DC converters is increasing. To achieve this goal, improved inductive components are required. New concepts include the fabrication of ferrite-metal-composite inductors. The ceramic multilayer technology and the LTCC technology (Low-temperature Ceramic Cofiring) are modern technologies that are frequently used to fabricate planar passives used in complex multilayer modules. LTCC technology is a promising technology for passive fabrication and 3-D integration. Ferrite tapes and paste and low-k capacitor tapes are used to fabricate planar embedded passives and they can be easily integrated into LTCC dielectric substrates to form complex modules. Based on the previous discussion, we are aiming at developing materials and processes for the fabrication of Ni(Cu)Zn ferrite-metal-composite multilayer inductors. This includes (1) the investigation of electric and magnetic properties of the Ni(Cu)Zn ferrites sintered under reducing atmosphere (2) the development of cofiring of Ni(Cu)Zn ferrite and base metal electrode (copper), and (3) the investigation of pressure-assisted constrained sintering technologies for Ni(Cu)Zn ferrite and FeSiCr alloy tapes as multilayer components under reducing atmosphere. This includes investigation on the stability of ferrite materials under low oxygen partial pressure conditions, and of correlations between composition, sintering behavior, microstructure, cation distribution, and functional properties of these ferrite materials, which are sintered at low temperature (900°C) and low pO2. Ni(Cu)Zn power ferrites with superior DC-bias superposition characteristics and metal components will be integrated using multilayer ceramic processing and low-pressure assisted constrained sintering technologies.This project is planned as cooperation between Prof. JörgTöpfer (University of Applied Sciences Jena, Germany) and Prof. Hsing-I Hsiang (National Cheng Kung University, Taiwan). The German group will focus on the investigation of the solid state chemistry and ferrite sintering under reducing conditions, whereas the Taiwanese group concentrates on the metal alloy components and their implementation into the multilayer process.