Small, light weight and multifunctional electronic components are attracting much attention because of the rapid growth of the wireless communication systems and microwave products in the consumer electronic market. The component manufacturers are thus forced to search for new advanced integration, packaging and interconnection technologies. One solution is the low temperature cofired ceramic (LTCC) technology enabling fabrication of three-dimensional ceramic modules with low dielectric loss and embedded silver electrodes. During the past 15 years, a large number of new dielectric LTCCs for high frequency applications have been developed. About 1000 papers were published and ∼500 patents were filed in the area of LTCC and related technologies. However, the data of these several very useful materials are scattered. The main purpose of this review is to bring the data and science of these materials together, which will be of immense help to researchers and technologists all over the world. The comme...

Low loss dielectric materials for LTCC applications: a review

The ability of engineered cerium oxide nanoparticles to confer radioprotection was examined. Human normal and tumor cells were treated with nanoceria and irradiated, and cell survival was measured. Treatment of normal cells conferred almost 99% protection from radiation-induced cell death, whereas the same concentration showed almost no protection of tumor cells. For the first time, nanoceria is shown to confer radioprotection to a normal human breast line but not to a human breast tumor line, MCF-7.

Vacancy engineered ceria nanostructures for protection from radiation-induced cellular damage

The nanoscience and nanotechniques have brought with new chance for new applications of some traditional materials, for instance, ceria-based materials, which are of great interest due to their wide applications, in particular, as redox or oxygen storage promoters in the three-way catalysts, catalysts for H(2) production from fuels, and solid state conductors for fuel cells. We highlight here current research activities focused on the controlled synthesis and assembly of ceria-based nanomaterials. We begin with a brief introduction to the urgency for research of ceria-based nanomaterials and our different consideration. Typical synthesis is then discussed with examples of nanosized ceria, ceria-zirconia solid solutions, and doped ceria developed by our group and the others. Controlled synthesis to manipulate the shape, crystal plane, and size is the topic of this article, with approaches elaborated for the assembly of ceria-based materials. Finally, we conclude this article with personal understandings and perspectives on this exciting realm.

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Controlled synthesis and assembly of ceria-based nanomaterials.

Additive manufacturing (AM) of ceramic materials has attracted tremendous attention in recent years, due to its potential to fabricate suitable advanced ceramic structures for various engineering applications. Robocasting, a subset of ceramic AM, is an ideal technique for constructing fine and dense ceramic structures with geometrically complex morphology. With the freedom and convenience to deposit various materials within any 3D spatial position, ceramic robocasting opens up unlimited opportunities, which are otherwise hardly attainable from other AM techniques. Here, a summary of the recent progress on the fabrication of single and multi-ceramic structures by robocasting is provided, as well as the prospects of achieving shapeable ceramic structures. The current challenges in ceramic robocasting and an outlook on its development, especially toward the fabrication of self-shaping ceramic structures, are also discussed.

Ceramic Robocasting: Recent Achievements, Potential, and Future Developments.

Numerical modelling is increasingly supporting the analysis and optimization of manufacturing processes in the production industry. Even if being mostly applied to multistep processes, single process steps may be so complex by nature that the needed models to describe them must include multiphysics. On the other hand, processes which inherently may seem multiphysical by nature might sometimes be modelled by considerably simpler models if the problem at hand can be somehow adequately simplified. In the present article, examples of this will be presented. The cases are chosen with the aim of showing the diversity in the field of modelling of manufacturing processes as regards process, materials, generic disciplines as well as length scales: (1) modelling of tape casting for thin ceramic layers, (2) modelling the flow of polymers in extrusion, (3) modelling the deformation process of flexible stamps for nanoimprint lithography, (4) modelling manufacturing of composite parts and (5) modelling the selective la...

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Multiphysics modelling of manufacturing processes: A review

Low temperature cofired ceramics (LTCC) technology has been widely used for high frequency components. Thick film copper is one of critical technology in microelectronic packaging. This paper focuses on low temperature ceramic cofired with copper. The difficulty with LTCC/Cu is organic material removal and copper circuit protection. By the careful control of the oxygen partial pressure in different sintering procedure, a quality multiplayer/copper system can be achieved. Different shrinkage characteristics of copper thick film and LTCC sheet result in delamination, cracking, and camber in the final products. Sintering promoters play an important role in the electrical conductivity and adhesion strength of copper thick film. The final structure of the sintered thick film appeared as three dimensional network structure. Approximately 8 wt.% glass promoter can match the shrinkage rate of the substrate and silver paste. LTCC has a low thermal conductivity, which limits its application in some fields. Thermal vias buried in LTCC substrate can resolve this problem.

Research of LTCC/Cu, Ag multilayer substrate in microelectronic packaging

Multilayer ceramic substrates with conductor traces are attracting a great deal of attention for their ability to increase packaging density for large-scale integration circuits. Currently one of the main methods used for the manufacture of flat ceramic packages with precise thickness control and consistency is the tape casting technique. It is crucial that the green tape thickness is controlled precisely and consistently. The fluid mechanics associated with the flow of a ceramic slurry during the tape casting process is analyzed. The flow of the slurry onto the casting surface can be modeled as a two-dimensional fluid flow through a parallel channel. The material of this study is an organic-bonded glass–alumina slurry and is modeled as a Bingham plastic fluid with a yield stress. The proposed model accurately described the fluid flow characteristics of the process, and has good agreement with experimental results.

Guangneng Zhang

Papers

Research of LTCC/Cu, Ag multilayer substrate in microelectronic packaging

Bingham plastic fluid flow model for ceramic tape casting