What are the classifications of surface mount capacitors?

Comprehensive classification and characteristic analysis of surface mount capacitors
1、 Classified by materials and processes
1. Multi Layer Ceramic Capacitor (MLCC)
Material: Ceramic media (such as X7R, X5R, C0G/NP0).
Structure: Multiple layers of ceramic plates stacked together, with metal electrodes plated on both ends.
characteristic:
Capacity range: 0.5pF~100 μ F, voltage coverage: 2.5V~100V.
Temperature characteristics:
C0G/NP0: Excellent temperature stability (± 30ppm/℃), suitable for high-frequency circuits.
X7R/X5R: Capacity variation of ± 15%, high cost-effectiveness, used for general filtering.
Y5V/Z5U: Capacity variation ± 22%, low cost, but poor temperature stability.
Application: High frequency, high-density circuits for mobile phones, computers, automotive electronics, and other devices.
2. Tantalum Capacitor
Materials: Tantalum metal (anode), manganese dioxide (cathode).
Structure: An oxide film is formed on the surface of the sintered tantalum block and immersed in the electrolyte.
characteristic:
Energy density: 3-10 times that of aluminum electrolytic capacitors, with a small volume.
Leakage current: low (typical value 0.01 μ A), high reliability.
Polarity: There are positive and negative poles, reverse connection may cause explosion.
Applications: military, aerospace, high-end consumer electronics (such as mobile phone motherboards).
3. Film Capacitor
Materials: Polyester (PET), Polypropylene (PP), Polyphenylene Sulfide (PPS).
Structure: Metal film winding, with electrodes formed by spraying gold on both ends.
characteristic:
High frequency characteristics: low loss (PP film tan δ<0.0001), suitable for RF circuits.
Voltage resistance: high (up to 1000V), with better safety than electrolytic capacitors.
Self healing: After local breakdown, the metal layer evaporates, restoring insulation.
Applications: power filtering, motor starting, LED driving.
4. Mica Capacitor
Materials: Mica sheet (dielectric), silver electrode.
Structure: Mica flakes and silver electrodes are alternately stacked.
characteristic:
Temperature stability: excellent (± 50ppm/℃), high temperature resistance (>300 ℃).
Accuracy: High (± 1%), suitable for high-precision circuits.
Applications: Aerospace, medical equipment, high-frequency oscillators.
2、 Classified by temperature characteristics (MLCC subclass)
1. C0G/NP0
Temperature range: -55 ℃~+125 ℃.
Capacity variation: ± 30ppm/℃.
Applications: RF circuits, precision timers.
2. X7R
Temperature range: -55 ℃~+125 ℃.
Capacity variation: ± 15%.
Application: General filtering, coupling circuit.
3. X5R
Temperature range: -55 ℃~+85 ℃.
Capacity variation: ± 15%.
Application: Consumer electronics power module.
4. Y5V
Temperature range: -30 ℃~+85 ℃.
Capacity change:+22%~-82%.
Application: Circuit with low cost and low precision requirements.
3、 Classified by special functions
1. Safety capacitor
Type: X capacitor (jumper power line), Y capacitor (line to ground).
Features: Through UL, VDE and other safety certifications, it can short-circuit or open circuit in case of failure, avoiding the risk of electric shock.
Applications: power adapters, home appliance EMI filtering.
2. Supercapacitors
Materials: Activated carbon (double-layer capacitor), conductive polymer (pseudocapacitor).
characteristic:
Capacity: 0.1F~1000F, far exceeding traditional capacitors.
Charging and discharging speed: seconds, suitable for energy recovery.
Application: Energy buffering for electric vehicles, backup power for smart meters.
3. Flexible Termination Capacitor
Structure: A flexible resin layer is added between the end electrode and the ceramic body.
Features: The anti bending ability has been improved to 8mm~10mm, avoiding breakage caused by PCB bending.
Applications: automotive electronics, wearable devices.
4、 Classified by packaging size
1. Metric dimensions
Common sizes: 0201 (0.6mm × 0.3mm), 0402 (1.0mm × 0.5mm), 0603 (1.6mm × 0.8mm), 0805 (2.0mm × 1.25mm).
Trend: 0201 and smaller sizes (such as 01005) are becoming popular in high-end smartphones.
2. Imperial size
Corresponding relationships: 0402 (British 01005), 0603 (British 0201), 0805 (British 03021).
5、 Summary
The classification of surface mount capacitors covers multiple dimensions such as materials, temperature characteristics, functions, and packaging. When choosing, it is necessary to comprehensively consider circuit requirements (such as frequency and accuracy), environmental conditions (such as temperature and vibration), and cost factors. For example, C0G/NP0 or thin film capacitors are preferred for high-frequency circuits, tantalum electrolysis or supercapacitors are selected for high-energy density scenarios, and safety capacitors are used to ensure equipment safety.