Veneer resistor (rectangular sheet resistor) is short for sheet fixed resistor. It is a metallic glass glaze resistor, which consists of four parts.
1 substrate: the substrate material is generally 96% alumina ceramic, not only needs good electrical insulation, but also needs excellent thermal conductivity. Electric energy and good mechanical strength at high temperature. The bottom plate must also be flat to ensure that the resistance and electrode paste can be printed in place.
2. Resistance film: the paste with certain resistance is printed on the ceramic substrate with certain resistance, and then sintered. Among them, the resistance paste is usually Ru dioxide.
3. Protective film: Cover the protective film on the resistance film to protect the resistance film. It can play the role of mechanical protection. Second, it can insulate the surface of the resistor to avoid faults caused by contact between the resistor and adjacent conductors. In the process of electroplating the intermediate electrode, the corrosion of the electrolyte to the resistance film can also prevent the degradation of the resistance performance of the electrode. The protective film is usually made of a low melting point glass paste by printing and sintering.
4. Electrode: the general electrode structure has three layers of electrode structure in order to make the resistance has good weldability and reliability, is the inner, middle and outer three layers of electrode. The inner layer is an internal electrode (printed and sintered from silver-palladium alloy) connected to the resistance body. The middle layer is the nickel plating layer, also known as the barrier layer. Its role is to improve the resistance to heat resistance, buffer the thermal shock during welding (to avoid causing the internal electrode to be fused by the solder). The outer layer is tin-lead layer, also known as the solderable layer is made of tin-lead alloy electroplating. Its role is to make the electrode have good solderability and extend the life of the electrode (tin-lead alloy electroplating).