The material selection of shunt resistors directly determines their measurement accuracy, temperature stability, and applicable scenarios. By analyzing the characteristics and technological evolution of different materials, they can be divided into the following categories:
1、 Mainstream metal alloy materials
Manganese copper alloy (MnCu)
Features: Extremely low temperature coefficient of resistance (TCR) (± 10 ppm/℃), low thermoelectric potential (EMF), and strong oxidation resistance.
Advantage: The first choice for high-precision current detection, especially suitable for scenarios that require long-term stability such as new energy battery management systems (BMS) and smart meters.
Limitations: High cost, high-power scenarios require heat dissipation design.
Constantan
Features: Low temperature drift, good corrosion resistance, excellent long-term stability.
Application: Industrial motor drive, frequency converter and other harsh environments, but with high thermoelectric potential (prone to errors when in contact with copper).
Nickel chromium alloys (such as NiCr, NiCrAlCu)
Features: Ultra low TCR (up to ± 1 ppm/℃), high mechanical strength.
Technical adaptation: Used for metal foil resistors (such as Vishay products), further improving accuracy through ceramic substrate temperature compensation.
Disadvantages: Poor welding performance, requiring special processing techniques.
Copper zinc alloy (brass)
Characteristics: Low cost, good conductivity, but significant temperature drift (TCR>100 ppm/℃).
Applicable scenarios: Overcurrent protection circuits with low precision requirements, such as power primary shunt.
2、 Special Materials and Structural Technologies
Metal foil resistor (such as block resistor)
Process: Nickel chromium alloy layer is photolithography on ceramic substrate, and TCR can be controlled within ± 1 ppm/℃.
Packaging differences:
Plastic sealed type: Low cost, but with average aging characteristics (annual drift of about 25 ppm);
Metal ceramic sealing type (gold seal): ultra-high stability (annual drift<2 ppm), used for measuring standard equipment.
Thin film/thick film hybrid technology
Deposition of high-precision thin films (such as manganese copper) on alloy substrates, balancing low TCR and high power density, suitable for surface mount shunt resistors (such as SMD 7343 packaging).
PCB integrated material
Pure copper wiring: The lowest cost, but with high temperature drift (copper TCR ≈ 3900 ppm/℃), software compensation is required.
Welding manganese copper strips: Welding alloy strips at PCB window openings to balance cost and accuracy, used for consumer electronic power supplies.
3、 Key dimensions of material selection
Sort by performance priority reference:
|Material | Temperature Coefficient (TCR) | Thermoelectric Force (EMF) | Applicable Current Range|
|Manganese copper alloy | ± 10 ppm/℃ | Extremely low | Medium high current (≤ 500A)|
|Nickel chromium alloy | ± 1-5 ppm/℃ | Low | High precision small current|
|Copper oxide | ± 20 ppm/℃ | Medium high | Medium current in industrial environment|
|Copper zinc alloy |>100 ppm/℃ | High | Low cost protection circuit|
4、 Material matching for typical application scenarios
New energy vehicles/BMS: manganese copper (low temperature drift ensures SOC accuracy);
Industrial frequency converter: Kangtong (corrosion-resistant and suitable for oil/vibration environments);
Precision instruments (such as medical equipment): gold sealed nickel chromium foil resistors (error<0.01%);
Consumer electronics power supply: thick film alloy surface mount resistors (such as SMD 4527, balancing volume and cost-effectiveness).
The material evolution of shunt resistors has always revolved around the "precision cost power" triangle balance:
Pursuing ultimate precision → Nickel chromium foil+gold seal (metrological grade);
Industrial reliability and cost balance → manganese copper/constantan (automotive/industrial control);
Consumer Electronics → Thin Film Alloy or PCB Integration Solutions. The future trend will focus on low-temperature drift+high-frequency (suitable for SiC/GaN devices), while environmentally friendly alloys (such as lead-free) will gradually replace traditional materials.