CL21 polyester film capacitor, also called metallized PET film capacitor, is the most mainstream series of polyester film capacitors. It adopts non-inductive winding structure with metallized polyester film as dielectric, coated with flame-retardant epoxy resin. It is widely used in low and medium frequency signal coupling, bypass, timing and general power supply filtering circuits of household appliances and industrial control boards. Many engineers and purchasers need to clarify its core characteristics and standard specifications before model selection to avoid parameter mismatch.

custom CL21 capacitor has obvious product features. It has excellent self-healing performance; once local breakdown occurs, the metal coating at the breakdown point will evaporate quickly to restore insulation and prevent short-circuit failure. With high dielectric constant of polyester material, it can achieve smaller overall size under the same capacitance and voltage, which is suitable for PCB layout with limited space. It is non-polarized, no polarity distinction during welding and assembly, convenient for mass production. Its operating temperature range is generally -55℃ ~ +125℃, good heat resistance, but the dissipation factor is relatively high, so it is not suitable for long-term high-frequency pulse circuits.

In terms of standard electrical specifications, the capacitance range of conventional CL21 series is 0.001μF ~ 10μF. Common tolerance grades include J (±5%), K (±10%), which can meet the precision requirements of most general circuits. Rated DC voltage options cover 50V, 63V, 100V, 250V, 400V, 630V, 1000V and 1250V. The withstand voltage test standard is 1.6 times rated voltage for 5 seconds. The pin pitch can be selected according to PCB pad design, including 5mm, 7.5mm, 10mm, 15mm, 20mm and other common sizes. weidy can adjust lead spacing, shell size and printing content according to customer drawings.

weidy film capacitor factory reminds that CL21 polyester film capacitor is mainly oriented to medium-low frequency scenarios. When the circuit works under high frequency, large current and high pulse conditions, it is easy to generate continuous heat due to high loss, resulting in accelerated aging. In this case, CBB polypropylene film capacitor is recommended instead. For high voltage working conditions above 630V DC, it is necessary to evaluate the ripple current and temperature rise of the whole machine, and reasonably reserve voltage margin.

CL21 series has stable supply, low comprehensive cost and rich specification matrix. It is the preferred component for cost-sensitive consumer electronics and small control boards. Before bulk procurement, it is recommended to confirm the rated voltage, capacitance tolerance, pin distance and size limit, and apply for samples to complete temperature cycle and load aging test, so as to ensure the long-term stability of terminal products.