Detailed explanation of the categories of surface mount resistors

Detailed explanation of the categories of surface mount resistors
As an indispensable basic component in electronic circuits, surface mount resistors are classified in various ways, covering multiple dimensions such as materials, functions, accuracy, packaging size, and application fields. The following is a systematic review of its core categories from a professional perspective:
1、 Classified by material and process
Metal Film Resistors
Process: Metal alloys (such as nickel chromium) are deposited on ceramic substrates using vacuum evaporation or magnetron sputtering techniques.
Features: Accuracy up to ± 0.01%, temperature coefficient as low as ± 1ppm/℃, and extremely low noise.
Applications: Precision measuring instruments, medical equipment, audio amplifiers.
Carbon Film Resistors
Process: Deposition of carbon film on ceramic substrate and formation of resistance value through laser resistance adjustment.
Features: Low cost, but average accuracy (± 5%~± 10%) and temperature stability.
Application: General consumer electronics, low demand circuits.
Metal Oxide Resistors
Process: Using metal oxides such as tin oxide as resistance materials, combined with thick film printing technology.
Characteristics: Excellent high temperature resistance, high frequency performance, and strong pulse resistance.
Applications: RF circuits, switching power supplies.
Thick Film Resistors
Process: Screen printing of conductive paste (such as ruthenate), followed by high-temperature sintering to form.
Features: Accuracy of ± 1%~± 5%, temperature coefficient of ± 100ppm/℃, high cost-effectiveness.
Application: General electronic products, power modules.
Thin Film Resistors
Process: A nanoscale resistance layer is formed through vacuum coating technology.
Features: Accuracy ± 0.1%~± 1%, temperature coefficient ± 5ppm/℃, excellent stability.
Application: Precision instruments, communication equipment.
2、 Classified by functional characteristics
Ordinary resistor
Including thick film, thin film, metal film and other types, it undertakes basic current limiting and voltage dividing functions.
Sensitive resistor
Thermistor (PTC/NTC): The resistance changes with temperature and is used for temperature compensation or overcurrent protection.
Photoresistor: The resistance value changes when the light intensity changes, suitable for light controlled switches.
Varistor: When the voltage suddenly changes, the resistance value drops sharply to suppress surge current.
Special function resistor
High voltage resistor: With a withstand voltage value of over 1kV, it is used in high-voltage power supply circuits.
High frequency resistor: designed with extremely low inductance (<1nH), suitable for RF circuits.
Alloy resistor: low resistance (<1m Ω), high power, used for current detection.
3、 Classified by resistance range
Low resistance resistor (<1 Ω)
Application: Battery protection board, motor drive current sampling.
Ordinary resistance resistor (1 Ω~1M Ω)
Application: Covering the vast majority of circuit scenarios, such as signal conditioning and voltage divider networks.
High resistance resistor (>1M Ω)
Application: Input impedance matching of instruments and meters, insulation detection.
4、 Classified by accuracy level
5、 Classified by packaging size
6、 Classified by application field
Automotive electronic specialized resistor
AC series: Complies with AEC-Q200 standard, resistant to vulcanization and vibration.
AT series: Thin film technology, low-temperature float, used for ECU and sensors.
Industrial control resistor
RE series: Thick film precision resistor, high stability, suitable for PLC and motor drive.
AF series: sulfur resistant design, extending the lifespan of outdoor equipment.
Consumer Electronics Resistors
RC series: Universal thick film resistor, cost optimized, used for home appliances and digital products.
Resistance in the field of new energy
Alloy resistor: low resistance, high power, used for battery management systems (BMS) and photovoltaic inverters.
Selection suggestions
Accuracy priority: Choose metal film or thin film resistors, such as medical equipment that requires ± 0.1% accuracy.
High frequency application: Metal oxide resistors with non inductive design.
High current scenario: using alloy resistors, such as current detection for electric tools.
Space limited: 0201/0402 packaging, but welding process feasibility needs to be evaluated.
By understanding the above classification system, engineers can choose the most suitable type of surface mount resistor based on specific needs, while balancing performance and cost optimization.