What are the materials of surface mount capacitors?

There are various types of materials for surface mount capacitors, and different materials determine the electrical performance, temperature stability, and applicable scenarios of the capacitors. According to the different dielectric materials of capacitors, they can be mainly divided into the following five categories:
1、 Ceramic media
NPO (COG) material
Characteristics: Excellent temperature stability (± 30ppm/℃), almost unaffected by temperature, voltage, and time; Low dielectric loss (tan δ ≤ 0.1%) and excellent high-frequency performance.
Capacity range: usually ≤ 1000pF, up to 10nF in high-precision scenarios (with higher cost).
Applications: high-frequency circuits, oscillators, RF modules (such as 5G base stations, satellite communication).  
X7R material
Characteristics: Medium stability (capacity variation ± 15% within -55 ℃~125 ℃), high capacity density; There is a DC bias effect (the effective capacity decreases when the voltage increases).
Capacity range: 100pF~47 μ F, supports medium and high voltage (up to 4000V).
Applications: power filtering, coupling circuits, consumer electronics motherboards (such as mobile phones/laptops).  
Y5V/Z5U material
Characteristics: Large capacity but poor stability (capacity variation can reach+22%~-82% within -30 ℃~85 ℃), high loss (tan δ ≥ 5%), and low price.
Capacity range: 1 μ F~100 μ F (highest capacity under the same volume).
Applications: Decoupling circuits, low-cost consumer electronics (such as remote controls, LED lights).
2、 Electrolytic media
Aluminum electrolytic capacitor
Structure: The anode is made of etched aluminum foil, the electrolyte is liquid electrolyte, and the cathode is encapsulated in an aluminum shell.
Features: Large capacity (0.1 μ F~6800 μ F), high voltage resistance (6.3V~450V); But it has poor temperature stability and a short lifespan (prone to drying up at high temperatures).
Application: Power input/output filtering (such as industrial power supplies, chargers).
 
 
tantalum electrolytic capacitor
Structure: The anode is made of tantalum metal, the medium is tantalum oxide film, and the cathode contains manganese dioxide or polymer.
Features: Small size, high capacity density, low leakage current; But the voltage resistance is limited (usually ≤ 50V) and the surge resistance is weak.
Application: Precise power supply for portable devices (such as decoupling of mobile phone CPUs).
Hybrid capacitors (such as RVE series)
Structure: Anode aluminum foil+solid polymer/electrolyte mixed cathode.
Features: Balancing high voltage resistance of aluminum electrolysis and stability of tantalum capacitors, with a long lifespan (>1000 hours at 105 ℃).
Identification: Top green or purple mark (such as Sanyo RVT series).
3、 Polymer film category
Polyester film (PET) capacitor
Characteristics: high dielectric constant, small volume, moderate capacity; Stability better than Y5V but weaker than X7R, suitable for mid to low frequencies.
Applications: Analog circuit coupling, consumer electronics (such as audio equipment).  
Polypropylene film (PP) capacitor
Features: Low high-frequency loss, excellent temperature characteristics (-40 ℃~105 ℃), strong resistance to pulse voltage.
Application: High frequency switching power supply, safety capacitor (X/Y type).
4、 Electrode and structural characteristics
Electrode material
Metal layer: Copper, aluminum, nickel based electrodes, with tin/silver plating on the surface to enhance conductivity.
Coating: Oxide/nitride film insulation layer to prevent short circuits and enhance corrosion resistance.
Structure Design
Single layer electrode: simple and low-cost, used for conventional capacitors.
Multi layer electrode (MLCC): Stacking ceramic dielectrics to achieve small volume and large capacity, reducing equivalent resistance (ESR).
Summary Table of Material Performance Comparison
Material type, temperature stability, capacity range, loss (tan δ), typical application scenarios
NPO (COG) ± 30ppm/℃ (optimal) ≤ 10nF ≤ 0.1% high-frequency oscillation circuit
X7R ± 15% (-55 ℃~125 ℃) 100pF~47 μ F 2.5% power filter/motherboard decoupling
Y5V/Z5U+22%~-82% (poor) 1 μ F~100 μ F ≥ 5% Low cost decoupling
Aluminum electrolysis difference (lifespan decreases with temperature) 0.1 μ F~6800 μ F 10%~20% high voltage power filter
Tantalum capacitor, medium 0.1 μ F~1000 μ F, 3%~8%, precision power supply for portable devices
Polypropylene film excellent (-40 ℃~105 ℃) 1nF~10 μ F ≤ 0.1% high-frequency switch/safety circuit
Key considerations for selection
High frequency scenario: Choose NPO (COG) or polypropylene film to ensure low loss.
High capacity requirements: choose X7R for medium voltage and aluminum electrolysis for high voltage; Use tantalum capacitors when space is limited.
Cost sensitive: Y5V or basic aluminum electrolysis, but with tolerance for performance fluctuations.
Lifetime reliability: Hybrid electrolytic or solid tantalum capacitors, suitable for high temperature environments.
Note: Material abbreviation meaning (EIA standard)
NPO/COG: Temperature coefficient ± 0ppm/℃ ± 30ppm/℃
X7R: -55 ℃~125 ℃ ± 15% capacity change
Y5V: -30 ℃~85 ℃+22%~-82% capacity variation.