Study On Structure And Properties Of Aluminoborosilicate Glasses Doped Rare Earth Oxides

Electronic fiber glass is an indispensable basic material of copper-clad laminate（CCL） andprinted circuit board（PCB）. It is not only used in high level computer, electronic facilities andsatellite positioning system of aerospace and sophisticated national defense industry but alsoused in people’s daily life, such as television, laptop and mobile phone et al. low dielectric fiberglass is the key to promote the development of electronic industry quickly. In recent years, withthe gradual upgrade request of electronic products, CCL must have the low dielectric constantand low dielectric loss which can reduce RC delay time and speed up the signaltransmission.The key to effect of these properties of CCL is the raw materials. Low dielectricfiber glass is the restricting factors in all materials.Aluminoborosilicate glass is known for its resistance to temperature change, lowexpansion coefficient and excellent corrosion resistance. Alkaline earth aluminoborosilicateglass has a wide-ranging applications, such as optical element, chemical and heat-resistantcontainers and fiberglasses etc. It also can meet the application requirements of low dielectricconstant glass fiber. Therefore, it is important to study the effect of composition on structureand properties.In this thesis, series of alkali-free aluminoborosilicate glasses doped with rare earthoxides were prepared by conditional melting and quenching technique. The effect of rare earthoxides on the structure and properties of aluminoborosilicate glasses were studied.The effect of different rare earth oxides on the structure and dielectric properties of glasswas studied. IR analysis indicated that doped different rare earth oxides had little effect on themain glass structure except for Nd₂O₃. The structure were mainly tetrahedral [SiO₄],[BO₄][AlO₄] and triangle [BO₃]. A little tetrahedral [AlO₆] were also found. With the increasingamount of rare earth oxides, the density increased. When the amount was6.0wt%, the densityincreased slowly, which attributed to non bridging oxygen and [BO₄] increased and the volumof [BO₄] was smaller than [SiO₄]. With increasing of atomic number of rare earth cationic, thedielectric properties and chemical durability decreased. With the concentration of rare earthcationic, the dielectric properties and chemical durability increased.Effect of mass ratio variation of SiO₂/B₂O₃, B₂O₃/Al₂O₃and （MgO, BaO, SrO, ZnO）/CaO on the structure and properties of alkaline earth aluminoborosilicate glass dopedLa₂O₃were studied. IR analysis showed that with the increasing of SiO₂substitution for B2O3,the glass structure enhanced firstly and then decreased because of boron abnormalphenomenon. The dielectric constant and loss hadn’t distributed linearly. It appeared extremevalues. And chemical stability improved. With the increasing of B2O3substitution for Al2O3,the tetrahedral [AlO₄] decreased and triangle [BO₃] increased. The glass structure decreased.The dielectric constant and loss decreased, because B2O3had lower polarizability thatimproved dielectric property. And chemical stability decreased. However, with the decreasingamount of Al2O3, the glasses were easy to crystallize, which was hard to form glass. Researchfound that mixed doping MgO and CaO in aluminoborosilicate glass could improve dielectricproperties. When MgO/CaO was0.4-0.6, dielectric constant and loss was lower. The acidresistance of the glass decrease and alkali resistance increase with alkali earth replacement ofCaO, while it appeared opposite trend with ZnO at the expense of CaO.Aluminoborosilicate glass doped a small amount of La2O3convert [BO₃] to [BO₄]. DTAanalysis indicated that doped rare earth in aluminoborosilicate glass decreased the meltingtemperature, and the thermal stability of glass was good. La₂O₃could reduce the meltingtemperature, and drawing process of the glass correspond the processing property. When theamount of La2O3was lower than3.0wt%, the dielectric properties were better than glassundoped La₂O₃.