The resistor sheet of a potentiometer (also known as an adjustable resistor or variable resistor) is its core component, which determines the performance, accuracy and applicable scenarios of the potentiometer. The following is a detailed description of the resistor sheet:

The basic structure of a resistor sheet

Material substrate: Typically ceramic, glass fiber or plastic, providing mechanical support and insulation performance.

Resistive layer: The conductive material coated on the substrate, whose composition and process determine the resistive characteristics.

Electrode: A metal contact (such as silver paste or copper) connected to a resistance layer at both ends, used for conducting current.

2. Types of resistance materials

According to application requirements, resistor sheet materials can be classified as:

Carbon film resistor

Material: Carbon particles and resin mixed coating.

Features: Low cost, relatively high noise, short lifespan, suitable for general consumer electronics (such as volume control).

Metal film resistor sheet

Material: nickel-chromium alloy or precious metal film.

Features: High precision (±1% to 5%), good temperature stability, suitable for precision circuits (such as medical equipment).

Conductive plastic resistor sheet

Material: Plastic matrix doped with conductive particles (such as carbon or metal).

Features: Strong wear resistance and long service life (up to millions of cycles), suitable for high-precision equipment (such as aerospace).

Wire-wound resistor sheet

Material: Wound with constantan or manganese-copper alloy wire.

Features: High power (up to tens of watts), high temperature resistance, but low resolution, used for industrial high current regulation.

3. Key parameters

Resistance range: a few ohms to a few megohms, depending on the material and geometry of the resistance layer.

Resistance linearity

Linear (Type B) : The resistance value varies uniformly with the rotation Angle.

Logarithmic (Type A) : Suitable for volume adjustment (the human ear's perception of sound is nonlinear).

Inverse logarithm (Type C) : Special applications (such as light intensity control).

Temperature coefficient: Metal film (±50~200 ppm/°C) is superior to carbon film (±500~1000 ppm/°C).

Rated power: Carbon film (0.1-2W), wire winding (5-50W).

4. Manufacturing process

Printing/Spraying: Carbon films or metal films are formed through mask printing or vacuum deposition.

Laser engraving: Adjust the width or thickness of the resistance trajectory to precisely control the resistance value.

Termination treatment: Silver-plated or gold-plated electrodes to reduce contact resistance.

5. Failure Modes and Improvements

Common Questions

The resistance layer is worn (the carbon film is prone to scratches).

Oxidation or contamination leads to poor contact.

Improvement measures

Lubricants are added to conductive plastics to reduce friction.

The sealed design is dust-proof and moisture-proof (such as IP67 grade).

6. Application selection suggestions

Low-cost applications: Carbon film resistors (such as toys, small household appliances).

High-precision requirements: Metal film or conductive plastic (such as sensor calibration).

High-power scenarios: wire-wound resistor sheets (such as motor speed regulation).