WEET Without Cutting Blank Resistors Rods

Core Material Composition of White Rod Resistors

The white rod resistor (also known as a "white bar-shaped resistor") typically consists of three main components: the resistive element, protective layer, and leads. The selection of core materials directly impacts the resistor's stability and applicable scenarios

1. Resistive material:

- Nickel-chromium alloy (NiCr): Most commonly used, with a resistivity of approximately 1.1×10⁻⁶ Ω·m (data source: *Electronic Component Materials Handbook*), featuring a low temperature coefficient of ±50ppm/°C, making it suitable for high-precision circuits.

- Carbon film: Low cost but poor precision, with a resistivity of approximately 3.5×10⁻⁵ Ω·m and a temperature coefficient of ±250ppm/℃, commonly used in consumer electronics.

- Metal oxides: such as ruthenium oxide (RuO₂), used in high-voltage environments, with resistivity between the two aforementioned materials.

2. Protective layer material:

- Encapsulated in ceramic or epoxy resin, with a temperature resistance range of -55°C to +155°C, and some industrial-grade products can reach up to +200°C (refer to IEC 60115 standard).

3. Lead material:

- Primarily composed of tinned copper wire, it offers excellent conductivity and corrosion resistance.

How do material properties affect electrical resistance performance?

1. Precision and Stability: Nickel-chromium alloy, due to its low temperature coefficient, ensures errors within ±0.1% in scenarios such as medical equipment, while carbon film resistors typically have an error of ±5%.

2. Power Tolerance: The white rod of the ceramic substrate exhibits superior thermal resistance, with a temperature rise 20% lower than that of epoxy resin encapsulation under 10W power (experimental data from TDK Technical Report).

3. Environmental Adaptability: The impedance change of metal oxide materials in humid environments is less than 1%, outperforming carbon film (which can exhibit changes up to 5%).