Materialization Study on Transformation of Low Temperature Co-fired Ceramic from TFT-LCD Waste Glass
Date Issued
2015
Date
2015
Author(s)
Fan, Chen-Shiuan
Abstract
A low-temperature co-fired ceramics (LTCC) was prepared from thin-film transistor liquid-crystal display (TFT-LCD) waste glasses using thermal treatments including glass-ceramic process and sintering process. The excellent dielectric properties of TFT-LCD waste glasses are original from it highly SiO2 content. However, the sintering temperature of TFT-LCD waste glass powder is higher than LTCC (900 oC). Therefore, TFT-LCD waste glasses need an adjustment in composition to lower its sintering temperature. Moreover, a dielectric constant of lower than 9 and quality factor higher than 300 were also required to meet the cretira of LTCC. The composition of TFT-LCD waste glasses is similar with CaO–Al2O3–SiO2 (CAS) and CaO–B2O3–SiO2 (CBS) system. Both systems are generally used in the production of commercial LTCC.With the regard, CaCO3, CaF2 and B2CaO4 were added as adjusting agents to TFT-LCD waste glass to produce LTCC in CAS and CBS system. The results indicated that the sintering temperature and dielectric properties of LTCC produced from composition-adjusted TFT-LCD waste glass were meet the creteria of commercial LTCC. In glass-ceramic process, the Ca ions weaken the net glass structure and lower the sintering temperature by acting as modifyin agent. In sintering process, the adding of B2CaO4 increased the quantities of liquid phases, which enhanced liquid sintering and the sintering temperature was reduced. The dielectric constant of LTCC depends mainly on its density and porosity. The dielectric constant of investigated CAS system is higher than CBS system due to the densification degree of CAS system is much higher. A reduction of quality factor can be observed with the increasing CaCO3 and B2CaO4 content. On the contrary, quality factor increased with the increasing addition of CaF2. This phenomen can be attributed to the substitution of oxygen ions by fluoride ions in the Si-O structure of glass. A fine, homogenous microstructure in LTCC can be achieved via glass-cermaic process. Then, minor defeat in microstructure makes a higher quality factor of LTCC. This study successful produced LTCC from composition-adjusted TFT-LCD waste glass, and the thermal and dielectric properties meet the creteria of commercial LTCC.
Subjects
TFT-LCD Waste Glass
LTCC
Dielectric properties
Type
thesis