In an era defined by Moore's law and escalating working frequencies, the intricacies of electronics design become ever more critical. The adoption of cutting-edge switching regulators amplifies the importance of meticulous capacitor selection. This article undertakes a comprehensive comparison between ceramic and electrolytic capacitors, shedding light on practical insights for informed decision-making.


Robustness Against Thermal and Vibrational Stress

For aficionados of vintage test equipment, the term "electrolytic plague" invokes memories of damage caused by electrolyte leakage. This phenomenon not only reduces capacitance but also corrodes PCBs.

Robustness Against Thermal and Vibrational Stress

Unlike their ceramic counterparts, Multilayer Ceramic Capacitors (MLCC) are impervious to such woes. Furthermore, they exhibit superior resilience to high temperatures, as their absence of electrolyte ensures immunity to heat-induced degradation. However, it's worth noting that certain MLCC families, if not vibration-proof, can be sensitive to vibrations.

TDK's whitepaper available at https://www.mouser.com/pdfdocs/TDK-FlexCrack-Countermeasures.pdf presents a comprehensive analysis. Employing soft-mounting MLCC families can alleviate this concern, considering that vibrational energy aligns with weight distribution.


Dimensional Advantages (Size & Weight): Miniaturization with MLCCs

The compactness of MLCC capacitors derives from their non-liquid electrolyte construction, rendering them substantially smaller and lighter. Thus, if size and weight are key factors, electrolytic capacitors lose their edge. A comparative visual of a Wuerth 885012109011 and an 865080443007 capacitor underscores this discrepancy. Weighing less than 100mg, the ceramic capacitor sharply contrasts the electrolytic capacitor's 270mg datasheet weight.

Dimensional Advantages (Size & Weight): Miniaturization with MLCCs

Capacity and Voltage Considerations

While MLCC capacitors boast smaller sizes, electrolytic capacitors counter with higher maximum voltages and larger capacities. For instance, while 16V MLCCs peak at 47 uF, electrolytic capacitors can reach up to 100V with the same capacitance. Notably, electrolytic capacitors can scale to capacities exceeding 10,000uF, as exemplified by the 861140786024 model.

Capacity and Voltage Considerations of capacitors 

It's important to recognize that larger electrolytic capacitors may pose challenges during placement via pick-and-place machines, making a discussion with the PCB assembly house prudent for efficient mass production.

Improved High-Frequency Behaviour

When traversing higher frequencies or navigating ripple-reduction scenarios, the capacitor's intricate network of parasitic elements becomes a critical consideration. Comparative analysis, as seen in the figure from Murata, portrays MLCC capacitors triumphing over their electrolytic counterparts across all parasitic elements.

Improved High-Frequency Behaviour of capacitor 

This superiority manifests in resonance characteristics, as demonstrated by Bode 100 impedance analysis. The higher resonant frequency of MLCC capacitors renders them ideal for switch-mode applications, as filtering high-frequency ripple with electrolytic capacitors becomes increasingly challenging.


Capacitance Stability Challenges

Piezoelectric effects pose a notable vulnerability within MLCC capacitors. Elevated voltage across the terminals triggers a reduction in capacitance, often resulting in substantial deviations, as depicted in illustrative videos.

Capacitance Stability Challenges of a capacitor 

These effects, referred to as derating, can diminish more than 50% of the rated capacity, contingent upon case size and voltage tolerance. Mitigation strategies, elucidated in datasheets, indicate that larger case sizes exhibit lower derating effects. Moreover, selecting a higher-rated maximum voltage delays the onset of derating, albeit at an elevated component cost. Systemic in nature, MLCC derating requires meticulous management to avert undesirable consequences.


Transitioning from Electrolytic to MLCC Capacitors

Transitioning from electrolytic to MLCC capacitors necessitates vigilance against parasitic oscillations attributed to the lower Equivalent Series Resistance (ESR). For guidance on this matter, refer to https://product.tdk.com/en/techlibrary/solutionguide/mlcc_replace-guide.html.

Transitioning from Electrolytic to MLCC Capacitors 

Combining MLCCs and electrolytics warrants caution to circumvent challenges arising from inductivity-induced impedance, as illustrated in the case of AbrIOT. Strategic consideration of these factors ensures a smooth transition and optimized circuit performance.


Prototyping Considerations

An intriguing facet emerges as MLCC capacitors can "sing" or function as microphones in specific scenarios. This audio-resonant behavior typically surfaces during prototyping, underscoring the significance of prototype runs before full-scale production.

Conclusion

The dichotomy between ceramic and electrolytic capacitors unravels through an intricate web of considerations. Balancing thermal resilience, size advantage, frequency response, and capacitance stability is pivotal for design excellence. As the realm of electronics evolves, the discerning engineer's grasp of these nuances will dictate the success of modern electronic systems.