Demo Highlights Long-Term Stability of Foil Resistors

January 28, 2016 by Jeff Shepard

VPG Foil Resistors announced today that its Vishay Foil Resistors (VFR) brand has released a new video demo that highlights the inherent advantages provided by the robust construction of VPG Bulk Metal® Foil resistors. The demo compares the stability of foil resistors with thin film and thick film technologies when exposed to a high-power pulse.

The resistor elements of thin and thick film resistors are composed of individual particles — consisting of conductive material for thin film and a mix of conductive and non-conductive material for thick film. As a result of this construction, both technologies have countless resistive interconnects and current paths between their particles. Foil resistors, on the other hand, feature a smooth, flexible, and homogenous construction.

In Vishay Foil Resistors' latest demo, the stability of the three resistor technologies is put to the test. Each resistor type is subjected to a 1000Vdc, 50W, 3000µs overload pulse, and its change in resistance value is recorded. As a result of the pulse, the thick film resistor is damaged and experiences a change in resistance, and the thin film device is completely destroyed. Due to the homogeneous nature of the foil resistor, however, it is able to absorb the pulse with no damage or change in value.

"Throughout its life, a resistor is exposed to numerous stressors — power ups and downs, heating and cooling, and expansion and contraction — all of which can cause it to change its value," said Richard Zuratt, VFR senior engineer. "Some resistor technologies change a lot, some a little, and some — like foil resistors — hardly at all. With its robust construction, the VPG Bulk Metal Foil resistor sets the standard for survivability and long-term stability, and is the resistor technology of choice in critical applications."