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In general, the failure rate of the resistance relative to other devices, it is relatively large low, so we generally evaluate the life of less resistance. But the failure rate will rise when high pressure and temperature, so some scenes, we still need to carefully evaluate the life of resistance.
Factors affecting the resistance of life:
(1) temperature, the temperature is too high it can burn quickly.
(2) pH environment, causing damage directly to the corrosion resistance.
(3) an external force, a force more than a certain limit, the resistance will break.
To extend the life of the resistance so that the heat dissipation is better to prevent the burning, the environment should be dry, non-pollutant, avoiding external force. Large resistance value resistor, the relative lifetime of the president. MΩ resistor is high level, due to the low power consumption, minimal environmental impact when used in a low pressure, generally very long life, no special attention (relative to other elements such as electrolytic capacitors, etc.). Big problems are generated when high voltages. When the high voltage operation, the resistor manufacturing process, the use of materials have considerable requirements. To consider the use of power tend to use the maximum possible (safety power value of the resistance is more than twice the actual operating power, improper design of some products, often using the power and resistance value is too close to the rated power), so that the temperature tolerance a basic requirement. The instantaneous pulse voltage and surge current will cause a fatal blow to the resistance. For a pin-poor welding, insulating process defective product, do not take long to collapse burn. Use the correct resistance, life is not a problem in more than 100,000 hours.
Therefore, such a high resistance as 1MΩ resistor to distinguish between high and there is general purpose. Specific resistance high pressure several times higher than the general resistivity price, but after all the resistance element is low, and the number of resistors used in a high pressure not many. For scenes of high voltage and high current, with sufficient derating, can improve the life of the resistor.
Therefore, in the case where the resistor is not used and the lifetime must be different. Resistance in different usage scenarios, service life will be different. Therefore, the life of the resistor are two: load life and shelf life.
Resistor load life Load Life, full name should be Load Life Stability. Resistors long at rated power load, the relative change in resistance percentage, a parameter indicating the length of life of the resistor.
The so-called resistive load life is estimated to be used in case of resistance lifetime, in fact, the life of the load resistance and the impact of these three factors related to resistance: resistance of power, temperature and time. Change in the resistance of the active resistance in the first few hundred hours of use, with the use of a longer time to stabilize. This is because over time, the resistance element itself tends to be stable, stress resistance element or between the substrate and the gradual release. Indicators resistive load life only through sample tests, by testing samples converted into a product life expectancy. Because this test requires at least 1,000 hours, and aerospace applications may require up to 10,000 hours of testing, and this test is a destructive test. Resistor load life, generally will be marked in the device profile, as shown in FIG.
Profile parameters of the life of the load resistance device theme
Refers to a resistance shelf life scene thermistor is not used, but when stored in the warehouse life. I.e. shelf life refers to the resistance of the resistance stability under storage conditions. Like shelf life and the life of the load resistor, the longer the storage time of the resistance, which resistance change is also stabilized. Some commonly used manufacturing equipment of precision instruments using precision resistors are not used immediately, but is stored again used some time, since better resistance value after a period of storage stability. Storing the resistance control with particular attention to humidity, humidity for any great impact resistance will resistance.
