What is the difference between carbon film resistors and metal film resistors

Update:18-05-2022
The EBW shunt resistor is made of nickel-chromium or similar alloy vacuum electroplating technology, and the film is deposited on the surface of the white porcelain rod, and the resistance value is adjusted by cutting to achieve the final required precision resistance value. Metal film resistors offer a wide range of resistance values, with higher resistance accuracy and tighter tolerances than carbon film resistors. Moreover, the heat dissipation of metal film resistors is better than that of carbon film resistors, and can adapt to harsher working environments. However, due to the current production process and the price of raw materials, the price of metal film resistors is much higher than that of carbon film resistors.
Carbon film resistors are currently the most widely used electronic, electrical appliances and information products, the cheapest price, and high reliability in quality stability. It is formed by separating the carbon of organic compounds from high temperature vacuum, closely adhering to the carbon film on the surface of the ceramic rod, and cutting and adjusting after appropriate joints, and coating the surface with epoxy resin for protection.
The difference between carbon film resistors and metal film resistors in appearance: the metal film has five color rings (1%), while the carbon film has four color rings (5%). The metal film is blue, and the carbon film is khaki or other colors. However, due to the improvement of the process and the appearance of the fake gold film, these two methods are not very good, and in many cases, the two resistors cannot be distinguished.

The better methods are the following two:
1. Scrape off the protective paint with a blade, the color of the exposed film is black, which is a carbon film resistor; the color of the film is bright white, which is a metal film resistor.
2. Since the temperature coefficient of the metal film resistor is much smaller than that of the carbon film resistor, you can use a multimeter to measure the resistance of the resistor, and then use the heated electric ferrochrome to approach the resistor. If the resistance changes greatly, it is a carbon film resistor. , and vice versa for metal film resistors.
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