Introduction: Why the Two Film Types Are Often Confused
CBB and CL capacitors are both non-polarized film capacitors. They commonly come in similar radial or axial packages, with comparable lead spacing and identical-looking capacitance and voltage markings. On a BOM or distributor product listing, they may appear almost interchangeable at first glance.
That said, they are not equivalent components. “CBB” and “CL” are series designations primarily used by Chinese and other Asian capacitor manufacturers. They are not standardized international part codes. Each label corresponds to a distinct dielectric film, and this material difference directly impacts dissipation factor, stability, physical footprint and cost.
This guide is intended for OEM engineering and purchasing teams. It clarifies the typical definition of each series, outlines their core differences, and lists key items to verify before approving cross-type substitution or releasing an RFQ. Electrical performance varies by product series and manufacturer. Always refer to the datasheet for the specific part number rather than relying solely on the general comparisons below.
What Is a CBB Capacitor?
Metallized polypropylene construction
A CBB capacitor is generally a polypropylene (PP) film capacitor, most commonly a metallized polypropylene type. International literature often labels this construction MKP. The electrodes are thin metal layers, typically aluminum or zinc-aluminum, deposited on the film. The film is wound into a roll, terminated, and encapsulated in an epoxy fill or a plastic case.
Common CBB series names include CBB21 and CBB22 (general-purpose metallized polypropylene), CBB81 (higher-voltage types often used in pulse or snubber duty), and CBB60 and CBB65 (AC motor-run capacitors). Series names and scopes vary by manufacturer.
Typical characteristics
Compared with polyester film, polypropylene is generally associated with:
- Lower dielectric loss (dissipation factor)
- Better stability over temperature and frequency
- Higher insulation resistance
- Larger physical size for the same capacitance and voltage, because of its lower dielectric constant
Manufacturer educational material cites typical dissipation factor values below 0.001 at 1 kHz for CBB-type parts. These are typical figures from published sources, not guaranteed limits, so confirm them against the datasheet for the specific series.
Metallized film capacitors have self-healing behavior. A local dielectric fault can vaporize the thin metallization around the defect and restore insulation. This capability is finite. It does not guarantee unlimited life or protect against sustained overstress.
What Is a CL Capacitor?
Polyester (PET) film construction
A CL capacitor is a polyester film capacitor built with polyethylene terephthalate (PET, commercially known as Mylar). Its metallized variants are widely referred to as MKT in international technical resources. The CL designation covers both metallized and foil-electrode types, so the sub-series code is critical. For instance, CL11 typically refers to foil polyester capacitors, whereas CL21 denotes metallized polyester capacitors. Always verify the internal construction against the manufacturer’s series specification.
Typical characteristics
Against polypropylene film, polyester film generally offers:
- Higher dielectric constant, enabling a smaller footprint at equal capacitance and voltage ratings
- Lower cost for equivalent ratings, although actual pricing varies by series, order volume and market conditions
- Higher dielectric loss, together with moderately degraded stability at high frequencies or across broad temperature ranges
Manufacturer reference data shows a typical dissipation factor below 0.01 at 1 kHz for CL capacitors. Just like CBB parameters, this value serves only for general benchmarking and is not a guaranteed specification.
Key Differences at a Glance
| Attribute | CBB (polypropylene, typically MKP) | CL (polyester, typically MKT) |
| Dielectric | Polypropylene (PP) | Polyethylene terephthalate (PET) |
| Typical dissipation factor at 1 kHz* | Lower (commonly cited as below 0.001) | Higher (commonly cited as below 0.01) |
| Typical insulation resistance* | Generally higher | Generally lower |
| Capacitance change with temperature | Generally more stable; temperature coefficient typically negative | Generally less stable; temperature behavior often nonlinear |
| High-frequency behavior | Generally better suited | Generally less suited |
| Size for equal capacitance and voltage | Larger | Smaller |
| Cost in comparable ratings | Generally higher | Generally lower |
| Self-healing | Yes (metallized types) | Yes (metallized types) |
| Typical use | Pulse, snubber, power, higher-frequency, precision circuits | General coupling, bypass, low-frequency filtering, cost-sensitive designs |
*Parameters differ by series and manufacturer. Always refer to the datasheet for the specific part number. The values shown are typical reference data from manufacturer guides and are not guaranteed specifications.
Regarding temperature ratings: do not assume which dielectric supports a higher maximum operating temperature. Reference materials vary, and temperature limits are series-dependent. Some common PP grades are rated 85 °C or 105 °C, while certain PET grades can reach 125 °C. Other product lines offer higher temperature ratings for polypropylene. Directly compare the published temperature range and high-temperature voltage derating from the respective datasheets.
Evaluating a Capacitor Alternative?
Choosing between CBB and CL capacitors requires more than matching capacitance and rated voltage. Share your part number, operating conditions, and key electrical requirements with LCA to discuss the specifications that need to be verified before substitution.
Contact LCA for Technical Support and RFQ Assistance
Application Considerations
Where CBB is typically specified
Designers typically specify CBB capacitors when low dissipation factor and stable performance are critical, or when the component must handle high pulse or ripple current. Typical use cases include:
- Switch-mode power supplies and DC-DC converters
- Snubber and resonant circuits
- Inverter and motor drive circuits
- DC-link and pulse applications (usually high-voltage CBB81-style series)
- Stable filtering and timing circuits where moderate precision is sufficient
- Audio signal paths, where low distortion is required
Where CL is typically used
CL capacitors are widely selected when PCB space and bill-of-material cost are the primary constraints, and electrical stress levels are moderate:
- General coupling and bypass
- Low-frequency filtering and decoupling
- Consumer electronics and home appliance control boards
- Cost-optimized power circuits with low ripple or pulse loading
Why substitution requires engineering review
Replacing a CBB with CL, or vice versa, merely because capacitance, voltage rating and lead pitch match is a frequent cause of field issues. Variations in dissipation factor alter self-heating under ripple current. Differences in temperature characteristics drift timing or filter response. Divergences in package footprint and internal construction impact mounting and thermal performance. A CL capacitor substituted for a CBB in pulse, snubber or high-frequency circuits cannot be considered suitable without formal engineering review. While a CBB replacement for CL may work electrically, it often introduces unnecessary extra cost and larger footprint with no performance gain.
Safety-rated duty note
Standard CBB and CL series are not intended for line-side EMI suppression unless the exact part holds the required safety certification (X or Y class per IEC 60384-14). Always obtain the compliance certificate and confirm it matches the part number.
Conclusion
CBB capacitors are built with polypropylene (PP) film, whereas CL capacitors adopt polyester (PET) film. In general, polypropylene delivers lower dissipation factor and superior stability, while polyester enables a smaller footprint and usually comes at a lower cost. Neither type is universally superior, and they must not be regarded as drop-in equivalents. When preparing RFQs or conducting substitution reviews, clearly specify the dielectric material, internal construction, voltage rating, temperature range and capacitance tolerance. All design approvals should be based on the datasheet and supporting documentation for the specific part number.
Frequently Asked Questions
Is a CL capacitor always cheaper than a CBB capacitor?
Often, but not always. Polyester parts are frequently less expensive in comparable ratings, but price depends on series, volume, and region. Verify with quotations.
Can I substitute a CL capacitor for a CBB capacitor in a power circuit?
Only after engineering review of dissipation, temperature rise, voltage, ripple or pulse capability, and expected lifetime. Do not assume equivalence from matching capacitance and voltage alone.
Which type handles higher temperature?
It depends on the series. Published sources differ, and ratings are specific to each product line. Compare the rated temperature range and derating curves on the datasheets.
Are CBB or CL capacitors suitable for mains connection?
Only if the specific part is safety-rated and certified for that duty (X or Y class under IEC 60384-14). Request the certificate.
Why does the same name sometimes mean different things?
CBB and CL are Chinese and Asian naming conventions and differ from IEC designations and manufacturer part codes. Always reference the full part number and datasheet.
Do CBB and CL capacitors have polarity?
No. Both are non-polarized film capacitors.
