Three‐phase borate solid solution with low sintering temperature, high quality factor, and low dielectric constant

2021 ◽  
Author(s):  
Rui Peng ◽  
Yuanxun Li ◽  
Su Hua ◽  
Yongcheng Lu ◽  
Liang Shi ◽  
...  
Keyword(s):  
Solid Solution ◽  
Dielectric Constant ◽  
Quality Factor ◽  
Sintering Temperature ◽  
High Quality Factor ◽  
Low Dielectric Constant ◽  
High Quality ◽  
Low Dielectric ◽  
Three Phase ◽  
Low Sintering Temperature

Properties and Microstructure of Mullite-Glass Ceramics for Multilayer Ceramic Substrates

1992 ◽  
Vol 264 ◽  
Author(s):  
N. Ushifusa ◽  
K. Sakamoto ◽  
S. Ogihara ◽  
T. Fujita
Keyword(s):  
Dielectric Constant ◽  
Thermal Expansion ◽  
Cooling Rate ◽  
Thermal Expansion Coefficient ◽  
Glass Phase ◽  
Sintering Temperature ◽  
Glass Ceramics ◽  
Low Dielectric Constant ◽  
Cooling Process ◽  
Low Dielectric

AbstractMullite (3Al2O3·2SiO2) has a low thermal expansion coefficient and a low dielectric constant making it a favorable material for substrate applications. Sintering of pure mullite ceramics is difficult, however, even above 1700°C. Thus, mullite-glass ceramics containing glass additives (Al2O3-MgO-SiO2 glass) which could be sintered at about 1600°;C were fabricated and their properties were investigated. The ternary system diagram of Al2O3-MgO-SiO2 shows that high SiO2 content glass depos its cristobalite at 200 to 270°C, which causes a substantial volume change, resulting in ceramic substrate cracking. Therefore it is particularly important to prevent crystallization of cristobalite from the glass phase in mullite-glass ceramics. The glass phase softens or partially fuses above 1600°C, and cristobalite formation in the glass phase occurs in the cooling process during firing. In order to obtain good substrates of mullite-glass ceramics, a higher temperature for sintering and faster cooling rate after firing are preferable. Analytical results by X-ray, SEM and EPMA show that mullite dissolves in the glass phase at a higher sintering temperature and more mullite crystallizes in the cooling process with a lower rate. The content of Al2O3 in the glass phase, therefore, increases with the increased sintering temperature and cooling rate, which may restrain crystallization of cristobalite. By adjusting of the composition of mullite and glass phase, mullite-glass ceramics with low dielectric constant (5.9), thermal expansion coefficient (3.5×10−6/°C) close to that of silicon chips, and high bending strength (210MPa) have been developed. These substrates made of mullite-glass ceramics are suitable for mounting silicon devices of computer processors.

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