)Substrate The aluminum oxide ceramic substrate generally used as substrate material should not only have good electrical insulation, but also have excellent thermal conductivity, electrical properties and mechanical strength at high temperatures. In addition, the substrate must be flat and the markings must be accurate and standard. , to fully ensure that the resistance electrode paste is printed in place) the resistance film is printed on the ceramic substrate with a resistance paste with a certain resistivity, and then sintered to form the resistance paste. The resistance paste is generally protected by a protective film of ruthenium dioxide
The film covers the resistor film, mainly to protect the resistor. On the one hand, it plays a mechanical protection role, and on the other hand, it makes the surface of the resistor insulating, preventing the resistor from contacting adjacent conductors and causing failure. During the process of electric transfer to the intermediate electrode, It can also prevent the erosion of the resistor film by the electrostatic fluid, resulting in a decrease in resistance performance. The protective film is generally a low melting point glass paste, which is printed and sintered. The electrode is to ensure that the resistor has good solderability and For reliability, a three-layer electrode structure is generally used. The inner, middle and outer electrodes are the internal electrodes connected to the resistor. The electrode materials should be selected to have small contact resistance with the resistor film, strong bonding with the ceramic substrate, good chemical resistance, and easy implementation. Electroplating operations generally use silver-palladium alloy printing and sintering. The middle electrode is a nickel-plated layer, also called a barrier layer. Its function is to improve the heat resistance of the resistor during welding, buffer the thermal shock during welding, and prevent silver ions from flowing into the resistor. The migration of the resistive film layer prevents the internal electrode from being corroded (the internal electrode is corroded by the solder). The tin-lead layer of the outer electrode is also called the solderable layer. Its function is to make the electrode have good solderability and prolong the storage of the electrode. The period is generally electroplated with tin-lead alloy
Rectangular chip resistors are divided into thin film resistors and thick film resistors according to the resistance material. The thin film resistors have high precision, small resistance temperature coefficient and good stability, but have a narrow resistance range. , suitable for precision and high-frequency fields, thick film resistors are the most widely used in circuits
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