1. Overview

Through Hole Resistors (THRs) are axial-leaded electronic components designed to limit current flow and divide voltages in circuits. They are mounted by inserting leads into printed circuit board (PCB) holes and soldering on the reverse side. As foundational passive components, THRs maintain circuit stability and precision across industries. Despite the rise of surface-mount devices, THRs remain critical for high-power applications and prototyping due to their durability and ease of manual handling.

2. Main Types and Functional Classification

3. Structure and Composition

Typical THRs feature:

• Lead Wires: Tin-plated copper or silver alloys for solderability
• Resistive Element: Carbon/metal film or wound nichrome wire
• Insulating Body: Ceramic or glass-epoxy coating
• Marking: Color bands (EIA-438B standard) or printed text

Advanced designs incorporate flame-retardant coatings and precision laser-trimmed elements for 0.01% tolerance.

4. Key Technical Specifications

5. Application Fields

• Consumer Electronics: Power management in TVs, audio equipment
• Industrial Control: Motor speed controllers, PLC systems
• Telecommunications: Signal conditioning in base stations
• Automotive: Engine control units, LED lighting systems
• Medical Devices: Precision measurement in diagnostic equipment

Case Study: Metal film resistors in ECG machines provide 0.1% tolerance for accurate heart signal detection.

6. Leading Manufacturers and Products

7. Selection Guidelines

Key considerations:

1. Determine required power dissipation (select 2x calculated wattage)
2. Match tolerance to application needs (e.g., 0.1% for audio amplifiers)
3. Verify temperature coefficient for operating environment
4. Consider voltage ratings for high-voltage circuits
5. Check RoHS compliance for environmental regulations

Example: Selecting a 10 , 10W wirewound resistor for a 24V DC motor driver circuit.

8. Industry Trends

Current development directions:

• Miniaturization while maintaining power ratings (e.g., 5W resistors in 1210 package)
• Advancements in laser trimming for sub-ppm level precision
• Adoption of eco-friendly materials meeting REACH/SVHC standards
• Integration with smart manufacturing systems for automated placement
• Development of high-temperature resistant models (up to 300 C operating)

Market growth projections indicate a CAGR of 4.2% through 2030, driven by automotive electronics demand.