How is the resistance accuracy of metal film resistors controlled?
Publish Time: 2024-12-18
Metal film resistors play a key role in the electronics field with their high resistance accuracy. Their accuracy control is a complex process involving many factors such as materials and processes.In terms of materials, the composition of the metal film is the basis for controlling the resistance accuracy. The metal film of metal film resistors is usually composed of metal materials such as nickel-chromium alloy (Ni-Cr). These materials have strict requirements on purity. High-purity metal materials can ensure the uniform and stable resistivity of the film. By accurately matching the alloy composition, the basic resistivity of the metal film can be accurately set, providing a basic guarantee for achieving the desired resistance accuracy in the future.Thin film deposition technology is a key process for controlling resistance accuracy. In the preparation process of metal film, commonly used methods include vacuum evaporation and sputtering. Taking vacuum evaporation as an example, in a high vacuum environment, the metal raw material is heated and evaporated so that its atoms are uniformly deposited on the ceramic substrate to form a thin film. In this process, the thickness of the metal film can be accurately controlled by accurately controlling parameters such as the temperature of the evaporation source, the evaporation time and the deposition rate. Precise control of film thickness is crucial for resistance accuracy because according to the law of resistance (R = ρL/S, where R is resistance, ρ is resistivity, L is length, and S is cross-sectional area), when the resistivity and film area are determined, a small change in film thickness (related to length) will directly affect the resistance value.After the metal film is deposited, a laser trimming process is required. This is a high-precision resistance adjustment method. The metal film is locally heated by a laser beam to partially evaporate or change its microstructure, thereby accurately adjusting the resistance value. The laser trimming system has high-precision positioning and energy control capabilities, and can fine-tune the resistance value of the resistor with extremely high accuracy according to the pre-set target resistance value, so that the resistance accuracy can reach a very high level, for example, the accuracy can be controlled within the range of ±0.1% or even higher.In addition, the quality inspection link runs through the entire production process. During the production process, a high-precision resistance measuring instrument is used to monitor the resistance value of metal film resistors in real time, and products with excessive resistance deviation are discovered and eliminated in a timely manner. In addition, through methods such as statistical process control (SPC), the production process parameters are dynamically adjusted to ensure that the resistance accuracy of each metal film resistor can meet the requirements of high-precision application scenarios, such as precision instruments, aerospace electronic equipment and other fields.
