CBB capacitor is a metallized polypropylene film capacitor with low dissipation factor, excellent high-frequency performance and small capacitance temperature drift. It is widely used in switching power supply, high-frequency inverter, resonance circuit, snubber and safety capacitor scenarios. Voltage, capacitance and pin pitch are three core parameters for selection. Improper matching will lead to heating, capacity attenuation, unable to weld and other problems. This tutorial sorts out the matching logic for hardware engineers and purchasing personnel.

First of all, match the rated voltage reasonably. The rated voltage of CBB capacitor must be higher than the actual continuous working voltage of the circuit, and a sufficient margin should be reserved. For DC filtering and general coupling circuits, it is recommended that the rated voltage be 1.2~1.5 times the working voltage. For circuits with high ripple, surge and pulse, the margin needs to be increased to 1.5~2 times. It is forbidden to select the capacitor with rated voltage lower than the actual working voltage, otherwise the capacitor will break down and fail. AC circuits such as X2 safety capacitors should select AC rated voltage specifications, and cannot simply use DC voltage to replace.

Secondly, confirm the capacitance value and tolerance. The capacitance is determined by circuit design requirements, such as filtering cut-off frequency, resonance frequency, RC time constant. Common capacitance of CBB series ranges from 0.001μF to several microfarads. The tolerance is mainly J (±5%) and K (±10%). Precision circuits such as resonance and sampling prefer J level with small tolerance; ordinary filtering can choose K level to control cost. Pay attention to the capacitance coding rule: 104 represents 0.1μF, 224 represents 0.22μF, and the third digit is the multiplier. custom CBB capacitor can support non-standard capacitance development when standard models cannot meet the design.

Pin pitch directly determines whether the capacitor can be installed on PCB. Common pin pitch specifications include 5mm, 7.5mm, 10mm, 15mm, 20mm, 25mm. It must be consistent with the pad spacing of the circuit board. If the pin pitch is too small or too large, manual welding and automatic plug-in cannot be completed. It is also necessary to check the overall body size, height and width, and reserve enough space to avoid interference with surrounding components and shell structure. When the standard pin pitch is not applicable, the original factory can customize the lead length and spacing.

weidy film capacitor suggests that after confirming the three major parameters, the working frequency, ripple current, operating temperature and safety certification requirements should be further checked. High-frequency pulse circuits need to focus on loss and temperature rise; export products need to select models with complete UL, CQC, VDE and ENEC certifications. Sample testing is an essential step before mass production. Test the temperature rise, withstand voltage and capacitance stability under real working conditions to avoid batch quality risks after mass production.

To sum up, the selection logic of CBB capacitor is: reserve voltage margin according to circuit working condition, determine capacitance and tolerance according to circuit function, and match pin pitch and body size according to PCB layout. Scientific parameter matching can give full play to the advantages of low loss and high stability of polypropylene film capacitors and improve the reliability of power electronic equipment.