| Summary: | 博士 === 大同大學 === 材料工程學系(所) === 99 === Solder glasses have been used in the areas of displays, microelectronics, and semiconductor technologies to fabricate glass-to-glass, glass-to-metal, glass-to-ceramic, and metal-to-ceramic joints. The major property-requirements for soldering are low softening temperature, thermal expansion coefficients match to the devices to be soldered, and acceptable chemical durability. Phosphate glasses, due to their low viscosities, are possible alternatives to PbO-based glasses. The major shortcomings of phosphate glasses are poor chemical durability and too high thermal expansion coefficient. In this research is to study the crystallization, thermal properties, and water durability of SnO-MgO-P2O5 solder glass. The results are as follows:
(1) Sintering, Crystallization, and Properties of SnO-MgO-P2O5 Glass
In this study, the SnO-MgO-P2O5 solder glass powder was fabricated. Sinterability, wetting, flowability, crystallization, and the resulting properties of the glass powder were investigated. It is shown that the powder compact can be fully densified above 362?aC and show good wetted to the substrate above 417?aC. The properties (coefficient of thermal expansion and chemical durability) of the sintered glass depend on the sintering temperature and are discussed in terms of the development of crystalline phases during sintering.
(2) Influence of Sintering Atmosphere on the Microstructure and Water Durability of
SnO-MgO-P2O5 Glass
In this study, effects of sintering atmosphere (Ar, air, and O2) on the sinterability and crystallization at 380?aC-470?aC of 60SnO, 10MgO, 30P2O5 (mole%) glass powder, and the water durability of the sintered glass were investigated. Increasing the oxygen partial pressure (PO2) in the sintering atmosphere enhanced the oxidation tendency of Sn2+ to Sn4+ near the surface region of the glass particles. Therefore, the glass viscosity was increased, resulting in the increase in both the temperature of densification and the temperature at which crystalline phases developed. Phase assemblage and the amounts of crystalline phases were also affected by PO2. The water durability of the sintered glasses is discussed in terms of the above microstructural parameters.
(3) Influence of Heating Atmosphere on the Properties of Stannous Phosphate Glass
In this study, a the 60 SnO - 40 P2O5 (mole%) glass was reheated at 280?aC (about 45?aC above the glass-transition temperature) for 20 min in various atmospheres (Ar, air, and O2), then the structure and surface-related properties were examined. It was found that increase in PO2 increases surface hardness, reduces optical transmittance, and improves chemical durability. The above phenomena are explained in terms of the increased oxidation tendency of Sn2+ to Sn4+ on the glass surface during reheating in increased PO2.
(4) Sintering, Crystallization, and Properties of SnO-MgO-P2O5 Solder Glass filled
with Low coefficients of thermal expansion filler. (Dry pressing method)
In this study, the ZrSiO4 (denoted as Z) and β-spodumene (denoted as S) ceramic powder were added into the 60SnO-10MgO-30P2O5 (mole%) glass powder (denoted as SMP) to reduce the thermal expansion coefficient of the sealing material. Effects of the addition of Z/S filler and the S particle size on the formation and properties of the Z/S-filled SMP composites were investigated. The Z/S particles would partially dissolve into the viscous SMP glass during sintering. The SMP glass with modified compositions also due to Z/S particles dissolution might have slow crystallization kinetic (composition effect). The internal porosity increased with increasing the amount of ceramic powder. Compare with the SMP glass, the current study shows that added ZrSiO4 powder improved the development of the S3P phase and β-spodumen powder inhibited the development of the S3P phase. The thermal expansion coefficient of the sintered bodies can be effectively reduced from 120 ?e 10-7/°C for pure SMP to 83 ?e 10-7/°C for Z/S-filled compositions.
(5) The SMP-Z-S composite for soldering Al2O3 substrate (Thick-film coating method)
In this study, the composite (SMP-Z-S) was used to join Al2O3 aubstrate. During the joining, although 60SnO-10MgO-30P2O5 (mole%) solder glasses can provide adequate flow at the soldering temperature, their thermal expansion coefficient are too high to match Al2O3 substrate. All of the SMP-Z-S composites showed good sealant for Al2O3 substrate.The composites can be soldering with Al2O3 substrete when the composites/Al2O3 is heated at lower temperatures (e.g., 407?aC) for 60 min-120 min, or at higher temperatures (e.g., 434?aC-470?aC) for 10 min.
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