Temperature Coefficient of Resistance (TCR) Measurement

Services

1. Introduction

Welcome to our comprehensive online testing service dedicated to measuring the Temperature Coefficient of Resistance (TCR). The specific resistance of materials can indeed change with temperature. The TCR is represented by the "alpha" (α) constant, which quantifies the change in resistance per degree of temperature variation. For pure metals, this coefficient is typically positive, indicating that resistance increases with temperature. In contrast, materials like carbon, silicon, and germanium exhibit a negative TCR, meaning their resistance decreases as temperature rises. Some metal alloys have TCR values close to zero, demonstrating minimal resistance changes with temperature variations—ideal for precision resistors.

2. Measurement methodology

To accurately measure the TCR, our testing service employs a controlled environment, such as a precision temperature chamber, enabling us to vary and measure temperature precisely. We utilize high-quality Digital Multimeters (DMM) or high-precision ohmmeters to obtain resistance values at different temperatures.

Once resistance values (R₁ at T₁ and R₂ at T₂) are obtained, the TCR (α) can be calculated using the formula:

α=(R₂−R₁)/R₁×(T₂−T₁)

where:

R1 is the resistance at temperature T1,
R2 is the resistance at temperature T2,
T1 and T2 are the temperatures in degrees Celsius or Kelvin.

This formula yields the TCR in parts per million per degree Celsius (ppm/°C). Our services adhere to standardized measurement methods, including MIL-STD-202 Method 304, which outlines procedures for measuring TCR over two distinct temperature ranges: from -55°C to 25°C and from 25°C to 125°C. We determine the highest measured value as the TCR, ensuring reliability for various applications.

3. Equipment and applications

For accurate TCR measurements, the critical specification is the linearity of the Analog-to-Digital Converter (ADC). This focus on linearity ensures that we can accurately determine changes in resistance, rather than solely measuring absolute resistance values.

a. Linearity: While TCR is often assumed to be constant over the measured temperature range, many materials display nonlinear relationships between temperature and resistance. Therefore, it's essential to specify the TCR alongside the temperature range.

b. Material Purity: The precise value of TCR can vary depending on the purity of the material tested and the temperature range employed.

c. High-Temperature Resistivity and Conductivity Testing

In addition to TCR measurements, we offer resistivity and conductivity tests across elevated temperatures. Our services comply with standards such as ASTM D257 and IEC 62631-3-1, making them ideal for applications involving materials in high-temperature environments, like heaters and resistive elements.

Understanding and measuring the Temperature Coefficient of Resistance (TCR) is crucial for a wide range of applications across various industries, including electronics, materials science, and manufacturing. Our TCR measurement and high-temperature testing services are essential for designing electronic components such as resistors and thermistors, where temperature sensitivity is critical. Additionally, we evaluate materials for use in high-temperature environments, like heaters and electrical contacts, and support the development of sensors that require accurate resistance changes for precise temperature readings. Furthermore, our services are instrumental in designing power systems that must withstand significant temperature fluctuations.

By understanding how resistance varies with temperature, you can ensure better performance, reliability, and accuracy in your applications. Contact us today to schedule your testing and gain precise insights into your material's resistance behavior under varying temperatures.

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