Plastic-Encapsulated Chip PTC Thermistor

Plastic-encapsulated chip PTC thermistors are positive temperature coefficient thermistors (PTC-k) packaged in surface mount technology (SMD) packaging. They are widely used in circuit protection, hőmérséklet érzékelés, and miniaturized electronic device designs. The following are their key features and selection considerations:
én. Core Features
‌Temperature Response Mechanism‌
Szobahőmérsékleten, the resistance is low (typically 1-20Ω). When the temperature exceeds the Curie point (e.g., 105°C), the resistance increases stepwise (up to several thousand ohms), providing self-current limiting.

The polymer matrix (PPTC) expands when overcurrent occurs, severing the conductive path and automatically recovering after the fault is resolved.

Product dimensions and recommended pad size

‌Packaging Advantages‌
Encapsulated with epoxy resin, they offer compact dimensions (e.g., 4524 és 2822 packages), making them suitable for high-density PCB layouts.
They are resistant to high temperatures and humidity, meet UL94-V0 flame retardancy standards, and are suitable for lead-free reflow soldering processes. RoHS-kompatibilis
Suitable for lead-free wave soldering and reflow soldering of surface mount technology
Plastic encapsulated chip package, materials meet UL 94 V-0 flame retardancy requirements
Utilizes high-performance thermistor chip for compact size and high performance
Maintains stable performance over a long period of time
Wide operating temperature range: -40°C to 85°C

II.. Selection Parameters

III. Typical Applications
Electrical instruments;
Security equipment;
Communications equipment;
Home appliances;
Automotive electronics;
Other power products requiring overcurrent, overvoltage, and surge protection

Circuit Protection: For overcurrent protection of USB ports and battery packs.
Temperature Compensation: Linear PTC models (such as the CMZ series) simplify temperature compensation design for precision circuits.
Automotive electronics: Meets wide operating temperature range of -40°C to 200°C.

IV. Technical Comparison

V. Mainstream Market Models

*SPSMD4032H450R#450 和SPSMD3225H450R#300 分别可用于 485 通讯接口保护抗 380VAKÁCIÓ 和 220VAKÁCIÓ。

‌JK-EK Series‌: 4524/2822 package, CQC/UL certified, suitable for LEDs and industrial equipment.

‌CMZL Series‌: Linear PTC, with controllable resistance-temperature gradient (±2000ppm/°C), suitable for automotive and medical applications.

Plastic-encapsulated chip PTC thermistors balance protection performance and space efficiency through an integrated design, making them an ideal solution for compact electronic devices.

VI. Precautions
General
To ensure the reliability of chip thermistors in actual use, extreme operating conditions should be considered during the design phase, and a certain margin should be allowed. Operating Environment
Környezeti hőmérséklet: -40-125°C
Relative Humidity: ≤95%
Atmospheric Pressure: 86-106 kPa
Vibration Frequency: 10-50 Hz
Acceleration: 98 m/s²

Storage
The chip thermistor should be stored in its original packaging. Do not open the packaging for storage.
Original Packaging Storage Conditions: Storage Temperature -25°C to +45°C, Annual Average Relative Humidity ≤75%, Maximum Not Exceeding 95%.
For chip thermistors, avoid contamination of the thermistor terminal surfaces during storage, handling, and processing.
SMD thermistors should be stored in environments that could affect their performance.
Use the chip thermistor within one year of receipt. After this time, recheck the solderability of the electrodes.

Transportation
The thermistor should be protected from dropping and impact during transportation.
It is recommended to wear gloves when handling the thermistor.
For chip thermistors, avoid contamination of the thermistor solder terminals during transportation.

Soldering (where applicable)
Sn96.5Ag3.0Cu0.5 solder paste is recommended.
Insufficient preheating may cause cracks in the thermistor ceramic chip.
The recommended maximum soldering temperature is 255±5°C for 3-6 másodpercig. Excessive soldering temperatures and extended soldering times may damage the thermistor.
Rapid cooling by immersion in solvent is not recommended.
After soldering, it is recommended to completely remove the flux or use a no-clean flux.