As the core component of current detection and power management, the packaging form of alloy resistors directly determines the adaptability of application scenarios. From consumer electronics to new energy vehicles, from precision instruments to industrial equipment, the packaging form of alloy resistors has undergone technological evolution from plug-in to surface mount, and from two-dimensional to three-dimensional. The following is a systematic review of the main packaging forms of alloy resistors:
1、 Plug in encapsulation (Through Hole)
Plug in packaging uses pins inserted into circuit board holes for soldering, suitable for high-power, high heat dissipation demand scenarios:
Axial Leaded Package
Representative models: RS-02K, RS-05K, RS-10K, etc. (named after resistance values).
Structural features: The resistor body is cylindrical in shape, with pins extending axially at both ends and a pin spacing of 2.54mm or 5.08mm.
Application scenarios: Industrial power supplies, motor drivers, battery management systems (BMS), and other scenarios that require high heat dissipation capabilities.
Advantages: Good heat dissipation performance, able to withstand high currents (up to tens of amperes); Easy for manual welding and maintenance.
Limitations: Large size, not conducive to high integration.
2、 Surface Mount Packaging (SMD/SMT)
Surface mount packaging is directly attached to the surface of the circuit board through solder pads, meeting the needs of automated production and miniaturization:
Rectangular patch packaging
Representative models: 2512, 2010, 1206, 0805, 0603, 0402, etc. (numbers indicate length and width, in inches).
Structural features: The resistor is rectangular in shape, with metal pads at the bottom, and no or only short pins.
Application scenarios:
2512/2010: High power current detection (such as server power supply, electric vehicle charging station), with a power of up to 5W.
1206/0805: Universal current detection (such as mobile phone and laptop battery protection), power 1-2W.
0603/0402: Precise current detection (such as smart watches, TWS earphones), power below 0.5W.
Advantages: Small size, light weight, suitable for automated production; Low parasitic inductance and excellent high-frequency characteristics.
Limitations: The heat dissipation capability is weaker than that of plug-in type, and it needs to be assisted by copper foil on the circuit board for heat dissipation.
Special shaped patch packaging
L-type/U-shaped packaging: The pins are bent in an L-shape or U-shape to enhance soldering stability, suitable for vibration environments such as automotive electronics.
Flip Chip Packaging: Resistors are directly inverted onto solder pads to shorten the heat conduction path and improve heat dissipation efficiency, used in high-end communication devices.
3、 Power type packaging
Specially designed packaging for high current scenarios, enhancing heat dissipation and current carrying capacity:
Metal Strip Packaging
Representative models: MSR series, CSR series.
Structural features: The resistor is made of metal alloy strip, fixed at both ends by welding or crimping, with a large heat dissipation area.
Application scenarios: Electric vehicle motor controller, photovoltaic inverter, industrial frequency converter (current up to several hundred amperes).
Advantages: low resistance (below 0.1m Ω), high power (up to tens of watts), strong anti pulse ability.
Limitations: Large size, requiring dedicated heat dissipation structure.
TO-220/TO-247 package
Structural features: The resistor is encapsulated in a metal casing, with pins extending from the bottom and capable of installing a heat sink.
Application scenarios: high-power power supplies, industrial lasers, requiring external heat sinks.
Advantages: Excellent heat dissipation performance, able to withstand transient overload.
Limitations: High cost and large space occupation.
4、 Customized packaging
Non standard packaging solutions provided for special needs:
Flexible Circuit Board Packaging (FPC)
Structural features: The resistor is directly printed on a flexible substrate and can be bent and folded.
Application scenarios: Wearable devices, medical patch sensors.
Advantages: High space utilization and adaptability to curved installation.
Limitations: Low power, requiring specialized processes.
3D Packaging
Structural features: High density integration is achieved through stacking or embedded design.
Application scenario: Current detection module in advanced packaging (such as SiP, SoC).
Advantages: Reducing size and improving signal integrity.
Limitations: Complex process and high cost.
Packaging Form Selection Guide
Current detection accuracy: For high-precision scenarios (such as medical equipment), surface mount packaging (± 1% accuracy) is preferred, while for high current scenarios (such as electric vehicles), power type packaging is preferred.
Power processing capability: Choose the package size based on power consumption, such as 0402 for packages below 0.5W, 2512 or metal strip package for packages above 5W.
Space limitations: Consumer electronics prefer micro patch packaging (such as 0402), while industrial equipment can accept plug-in or TO-220 packaging.
Cost sensitivity: Choose standardized packaging for general scenarios (such as 0805), and consider customized packaging for special needs.
Technology Trends
Miniaturization: evolving from 0402 to 0201 or even 01005 packaging to meet the needs of wearable devices.
Integration: Integrate with temperature sensors and MCU to develop intelligent fuse modules.
Material Innovation: Adopting nano alloy materials to enhance power density and reliability.
The packaging form of alloy resistors is an art of balancing technology, cost, and application scenarios. The evolution of packaging forms from plug-in to surface mount, from two-dimensional to three-dimensional not only reflects the progress of electronic technology, but also reflects the eternal pursuit of miniaturization, high performance, and low cost in terminal products.