Vishay Precision Group Inc's Vishay Foil Resistors brand (VFR) has released a new video that demonstrates the advantages of using Bulk Metal Foil resistors in high-humidity environments. The video compares the etching process and survival times for thin film and Bulk Metal Foil nickel-chrome alloy (NiCr) resistive elements as they are tested in 100 per cent humidity conditions.
All resistors that are based on nickel-chrome alloy, a category that includes thin film as well as Bulk Metal Foil devices, are susceptible to electrochemical corrosion or etching when placed in a high-humidity environment and powered with a very low wattage. However, because the nickel-chrome element of a Bulk Metal Foil resistor is hundreds of times thicker than the element in a thin film device with the same value, it will last much longer under these conditions.
To illustrate this concept in the video, a few ounces of hot water are poured into an insulated bottle to simulate a high-humidity environment. Uncoated 1206 thin film and foil resistors are powered up at 1 mW and suspended in the bottle while being monitored for ΔR and ppm deviation from their initial value. Uncoated resistors are used to accelerate the humidity effect.
In the test, the thin film device etched through and failed after only two minutes and 13 seconds. Even after one hour, however, the foil resistor was unaffected. As demonstrated by the test, because of the inherent robustness of the Bulk Metal Foil element, VFR resistors are capable of surviving in a high-humidity environment much longer than nichrome thin film resistors.
Link to video by clicking HERE.
For more information, visit www.vishaypg.com