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.
Taphonomy of Isisfordia duncani specimens from the Lower Cretaceous (upper Albian) portion of the Winton Formation, Isisford, central-west Queensland
Taphonomic analysis of fossil material can benefit from including the results of actualistic decay experiments. This is crucial in determining the autochthony or allochthony of fossils of juvenile and adult Isisfordia duncani, a basal eusuchian from the Lower Cretaceous (upper Albian) distal-fluvial-deltaic lower Winton Formation near Isisford. The taphonomic characteristics of the I. duncani fossils were documented using a combination of traditional taphonomic analysis alongside already published actualistic decay data from juvenile Crocodylus porosus carcasses. We found that the I. duncani holotype, paratypes and referred specimens show little signs of weathering and no signs of abrasion. Disarticulated skeletal elements are often found in close proximity to the rest of the otherwise articulated skeleton. The isolated and disarticulated skeletal elements identified, commonly cranial, maxillary and mandibular elements, are typical of lag deposits. The holotype QM F36211 and paratype QM F34642 were classified as autochthonous, and the remaining I. duncani paratypes and referred specimens are parautochthonous. We propose that I. duncani inhabited upper and lower delta plains near the Eromanga Sea in life. Their carcasses were buried in sediment-laden floodwaters in delta plain overbank and distributary channel deposits. Future studies should refer to I. duncani as a brackish water tolerant species.