Metal Foil Resistors: An Overview

Resistors are common passive components found in countless electronic circuits, and they are often used to reduce current flow, terminate transmission lines, divide voltages, and much more. To accommodate a wide variety of electrical needs, resistors come in many shapes and forms. Metal foil resistors in particular are a popular option for high precision applications, offering ample performance over alternate options alongside accuracy, stability, and speed. With their implementation within aerospace applications, instrumentation, and other settings, it can be beneficial to understand their use and operational characteristics.

For applications that require high precision and minimal deviation from set temperature ranges, a low temperature coefficient of resistance (TCR) is necessary. As such, the low TCR of metal foil resistors makes them extremely useful for numerous applications. When temperatures rise during standard operations, the resistance of the foil will increase as well. Simultaneously, the rise in temperature will also result in compressive stress placed on the foil, effectively reducing its resistance. As both effects counteract one another, a balance is struck as the resistor remains quite stable. This balance is also bolstered by the low power coefficient of resistance they exhibit, further mitigating self-heating through power dissipation. With various advancements made to metal foil resistors, one may now procure such parts with a TCR at or below ±0.05ppm/°C.

Alongside TCR values, the thermal stabilization of metal foil resistors is also a major benefit of such circuit elements. Generally, thermal stabilization refers to the measurement of speed for a device’s resistance to stabilize in response to a change in temperature. Thermal stabilization may be fulfilled through various means, some resistors utilizing ambient temperature adjustments or self-heating as power dissipation increases. Having optimal thermal stabilization is a necessity for precision circuits, and metal foil resistors far surpass their competitors in terms of their stabilization values. While other resistors may take upwards of minutes to stabilize, metal foil resistors only require seconds.

While various temperature properties can determine whether or not a particular resistor is fit for a given application, response times are also crucial. Parasitic inductance and capacitance are both undesirable effects during power transmission, and they can cause the distortion and degradation of signals. With a metal foil resistor, minimal parasitic inductance and capacitance is achieved, that of which surpasses other various types such as the wirewound resistor. With the pattern of the foil on the resistor, parasitic reactance is mitigated. This is achieved through the use of S-shaped or zig-zag patterns, those of which force current in adjacent wires to flow in different directions. With the response times provided by metal foil resistors, such circuit elements perform with ease while in high-frequency systems.

When you are deciding between various resistor types for a particular application, it is important to determine exactly what you require to find an optimal fit. For example, metal foil resistors are best utilized in situations where high precision and long-term stability is a necessity. As such, they are commonly found within high precision instruments, differential amplifiers, audio circuits, medical devices, aerospace technology, and more.

If you find yourself in need of various metal foil resistor components and other resistor types, let the experts at Stacked Purchasing help you secure everything that you need with unmatched pricing and lead-times for your benefit. With our supply chain network stretching across the United States, Canada, and the United Kingdom, we are able to expedite shipping to meet the time constraints of our customers. Furthermore, we also strive to always fulfill AOG requirements, offering same-day shipping and/or delivery on select in-stock items. Get in contact with one of our representatives today and see how Stacked Purchasing is revolutionizing the procurement process for our customers’ benefit.