Banca de QUALIFICAÇÃO: SERGIO AUGUSTO NASCIMENTO DE FRANÇA JUNIOR

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : SERGIO AUGUSTO NASCIMENTO DE FRANÇA JUNIOR
DATA : 25/10/2019
HORA: 10:00
LOCAL: Sala de aulas do PPGCEM
TÍTULO:

Obtaining dielectric substrates based on calcium silicate with different additions of h-BN by tape casting.

PALAVRAS-CHAVES:

Tape casting, ceramic laminates, vitroceramics, h-BN, high frequency substrate.

PÁGINAS: 82
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
RESUMO:

In recent years, considerable progress in the internet of things (loT), microwave telecommunications, satellite transmission systems, intelligent transport (ITS), and dense microelectronic circuits has resulted in a growing demand for new low dielectric loss materials. Ceramic substrates for these purposes should generally have low relative dielectric constant, low dielectric loss under high operating frequencies and high thermal conductivity. Hexagonal boron nitride (h-BN) has great potential as a substrate for high frequency applications due to its low constant and dielectric loss and high thermal conductivity. Glass ceramic materials have also been widely used due to their low cost and good dielectric properties. In view of this, the objective of the present work was to obtain multilayer calcium silicate ceramic substrates with different additions of h-BN (1 wt.%, 3 wt.% and 5 wt.% ) conformed by tape casting, to evaluate their use as high frequency substrates. The viscosity of the ceramic suspensions was analyzed by rheological tests and the green ceramic tapes were submitted to thermal analysis (TGA and DTA). The ceramic tapes were laminated and sintered at three different temperatures: 950 ° C, 1000 ° C and 1050 ° C. The sintered laminates were characterized by X-ray diffraction, density and porosity tests were performed by the Archimedes technique and the fracture surface of the laminates was analyzed by scanning electron microscopy (SEM-FEG). Finally, the dielectric properties of the green and sintered laminates were obtained. The results showed a pseudoplastic behavior of the suspensions, ideal for tape casting technique. Reflection peaks concerning the wollastonite, triclinic, and cristobalite, tetragonal, were found for all compositions at all sintering temperatures. Scanning electron microscopy images revealed the presence of platelet-shaped h-BN in the microstructure. The high relative values of porosity found for all compositions determined the low relative dielectric constant values (between 1.9 and 2.35), and revealed that there was a partial sintering process of the samples. In general, the increase in h-BN content at all sintering temperatures decreased dielectric losses at frequencies from 0.1 GHz. The lowest dielectric loss obtained was 0.0001 for the composition containing 5 wt.% h-BN sintered at 1050 ° C at a frequency of 0.5 GHz.

MEMBROS DA BANCA:
Externa à Instituição - Ana Paula da Silva Peres - UFRN
Externa à Instituição - SHEYLA KAROLINA JUSTINO MARQUES - IFAl
Presidente - 1149564 - WILSON ACCHAR