Study On The Silver Paste Of Hot Wires For Auto Rear Glass

The hot wires of auto rear glass can be used for rapid elimination of the frost on the windshield, and that make the car run more stable and safely. In order to make the silver paste satisfy the demand for high-grade vehicles, the author researched on the adhesion ,acid resistance ,electrical conductivity and another indices of the hot wires.Based on theoretical study of the hot wires and the function of each paste component, the material systems of paste for hot wires, including organic system satisfying printing process of hot wires and glass system coordinating with the tempered glass were designed. The paper researched on glass frits for hot wires including series Bi₂O₃-B₂O₃-SiO₂ glasses. The effect of the ZnO, Al₂O₃ ,TiO₂ and other oxides on the softening temperature and acid resistance of glass frits was studied, and the the reason that causes the softening temperature and acid resistance variations were also analyzed in this paper. Adding Al₂O₃ and TiO₂ to improve the acid resistance, we have prepared glass frits for hot wires through adjusting the ratio of ZnO and a bit of alkali metal oxide. As stated previously, the composition of the glass frits for hot wires was given out (wt%): (Bi₂O₃ +B₂O₃ + SiO₂): (Al₂O₃ + ZnO +MgO):(TiO₂+ZrO₂) =83:14:3.The effect of the series Bi₂O₃-B₂O₃-SiO₂ glasses and PbO-B₂O₃-SiO₂ glasses on the acid resistance and adhesion of silver paste were discussed. The results show that ,there is little difference of adhesion between the hot wires containing different series glasses with the same softening point, though the acid resistance of hot wires by Bi₂O₃-B₂O₃-SiO₂ glasses slightly superior than PbO-B₂O₃-SiO₂ glasses. The effect of the content of glass frits on the acid resistance ,adhesion, and conductivity of hot wires, the effect of the softening point of glass frits on the acid resistance, the effect of the content of silver on the conductivity were all discussed in this paper. With the help of scanning electron microscope (SEM), we have learned that the main reason why the hot wires drop from windshield is the corrosion behavior of glass in acidic solution and that the acid resistance of the conductive hot wire is closely related with the densification of silver film.Finally, compounding formula of the silver paste for hot wires was designed. The comprehensive test of hot wires was tested by professional manufacturers, and the result show that silver paste we made is suitable for use in hot wires because of its advantages such as dense films, adjustable colour, excellent adhesion and good acid resistance.