Study On High-power Thick-film Resistor Pastes

The development of thick film technology was reviewed and pursued. High-power thick film resistor pastes have been studied due to good applying potential. State-of-the-art techniques such as rolling, screen printing and sintering were used for sample preparation. Effects of process, conductor and glass on the properties of thick film resistor (TRF) have been analyzed with XRD, DTA and electrical tests. Series of high-power Ag-Pd resistor pastes were developed in this study. The feasibility of research on high-power bismuth ruthenate resistor paste was also discussed briefly.Effects of the fabrication process on the properties of thick film resistor pastes have been investigated. It was showed that the resistor pastes were more suitable to be printed when the viscosity was in the range of 200-300 Pa·s. The leveling and dispersibility of the thick film paste would be both good when the percentage of span85 as surfactant in the organic vehicle was 3wt%, or that of lecithin was 0.5wt%. The stability of refiring of Ag-Pd TFR would be best when the thickness of fired film was about 12 μm and the even particle size of glass was about 3 μm. The best peak firing temperature was existed, which was between the softening temperature and the peak crystallization temperature, and near the incipient crystallization temperature of the glass.Effects of the components and microstructures of thick film resistors on its properties have been investigated. It was found that the relative content of Ag to Pd (Ag/Pd) was the most important factor affecting the temperature coefficient of resistance (TCR) of Ag-Pd TFR. And the content of glass was the most important factor in resistivity of thick film resistor. The TCR of TFR decreased as the Ag/Pd was lower. The resistivity of TFR increased as the glass content was higher. It was showed that the resistivity increased rapidly with the glass content after the glass content was more than 75.4vol%. And at the same time the stability of refiring became worse. Effects of the softening temperature, the crystallization temperature and the coefficient of thermal expansion of glass on the properties of TFR have also been discussed.A new method to make bismuth ruthenate was developed in this paper. By this method, the price of the raw material would be much lower by replacing bismuth oxide and ruthenium oxide with other bismuth compound and ruthenium. In addition, it was founded that resistivity and TCR would be both lower as Ag and Pd were added into the bismuth ruthenate resistor paste. It was proved that series of high-power bismuth ruthenate resistor paste could be manufactured theoretically.The properties of the high-power Ag-Pd resistor pastes developed in this paper were as followed: (1) the resistivity ranged from 50mΩ/□ tolΩ/□; (2) the TCR ranged from 300ppm/℃~1500 ppm/℃; (3) the value of the chang rate of resistivity after refiring was lower than 5%。 Intermediate resistivitier may be obtained by blending the two members of a TCR group. This series has brought about industrialization successfully 。...