Methods of measurement of LTCC metallization thickness
Metallization provides electrical routing and serves as thermal via in LTCC (Low Temperature Cofired Ceramic) technology. High electrical and thermal conductivity is desirable. It is often achieved with the use of low electrical resistance materials, such as gold, silver and copper. The conductive paste made of these materials is expensive. Hence, the fabrication of LTCC has to be performance-wise and cost effective. The width, length and thickness of metallization are associated with the amount of conductor paste used. The thickness of metallization governs the functionality and performance of some components, such as resistor. In this paper, the physical attributes of LTCC substrate and its metallization was studied. Due to the constraint brought by the physical attributes of LTCC samples, various methods had been carried out. This paper also summarized the pros and cons of each method. The methods are limited to the equipment available.
Curvature evolution in LTCC tapes and laminates
Low temperature cofired ceramic (LTCC) substrates provide a low-cost packaging approach for radio frequency (RF) integrated circuits. Thermally-driven curvature development in these LTCC tapes and laminates, which can introduce property-limiting defects into a device, was examined quantitatively using an optical profilometer. Contrary to the standard perception of tape cast products, these specimens consistently experienced the largest increases in curvature during burnout rather than during sintering. Sintering actually leads to dramatic decreases in curvature. Slight anisotropic changes in curvature were observed when comparing those directions parallel and perpendicular to the tape casting direction. In the laminates, individual layer orientations had strong effects on overall curvature. Springback after the application of lamination pressure strongly contributes to curvature. "Microslumping" at the ends of the tapes/laminates occurred during sintering and could be accounted for via discrete element models of sintering. The latter phenomenon can be eliminated by controlling relative tape orientation.
Integrating Al with NiO nano honeycomb to realize an energetic material on silicon substrate
Nano energetic materials offer improved performance in energy release, ignition, and mechanical properties compared to their bulk or micro counterparts. In this study, the authors propose an approach to synthesize an Al/NiO based nano energetic material which is fully compatible with a microsystem. A two-dimensional NiO nano honeycomb is first realized by thermal oxidation of a Ni thin film deposited onto a silicon substrate by thermal evaporation. Then the NiO nano honeycomb is integrated with an Al that is deposited by thermal evaporation to realize an Al/NiO based nano energetic material. This approach has several advantages over previous investigations, such as lower ignition temperature, enhanced interfacial contact area, reduced impurities and Al oxidation, tailored dimensions, and easier integration into a microsystem to realize functional devices. The synthesized Al/NiO based nano energetic material is characterized by scanning electron microscopy, X-ray diffraction, differential thermal analysis, and differential scanning calorimetry.