The Capacitance Deviation of high Capacitance MLCC

In the realm of electronics manufacturing, Multilayer Ceramic Capacitors (MLCCs) are the unsung heroes, playing a crucial role in a vast array of devices. However, recently, there has been a growing concern among some users about MLCCs with seemingly low capacitance, which has led to speculations about quality issues. In this article, we aim to demystify this phenomenon and clarify that it is not a matter of poor quality.

 

 

MLCCs are rigorously tested before leaving the factory. Manufacturers adhere to strict quality control protocols, ensuring that every single MLCC leaving the production line has been 100% tested and meets the predefined standards. So, when a deviation in capacitance is observed, it's essential to look beyond the surface and understand the underlying reasons, especially for Class II MLCCs, which seem to be the focus of many concerns.

 

The Impact of Environmental Temperature

 

One of the primary reasons for the perceived low capacitance in Class II MLCCs is the influence of environmental temperature. The dielectric materials used in these capacitors have inherent properties that cause the capacitance to change with temperature fluctuations. This is a well - documented and industry - wide phenomenon. As the temperature rises or falls, the internal molecular structure of the dielectric material is altered. For instance, an increase in temperature may cause the molecules to vibrate more vigorously, affecting the electric field within the capacitor and ultimately leading to a change in capacitance.

 

All major manufacturers have detailed specifications and technical notes (attached for your reference) that clearly illustrate how the capacitance of Class II MLCCs varies with temperature. It's important to note that this is not a sign of a defective product but a characteristic of the material itself. When using MLCCs in electronic devices, designers must account for this temperature - related capacitance change to ensure optimal performance.

 

Natural Capacitance Decay over Time

 

Another factor contributing to the observed capacitance deviation is the natural decay of capacitance over time. Class II MLCCs experience a gradual decrease in capacitance as they are stored. This is a natural consequence of the chemical and physical changes occurring within the capacitor's structure during storage. However, this is a reversible process.

 

A standard annealing procedure can effectively restore the capacitance to its original value. During the annealing process, which typically involves heating the MLCCs to a specific temperature (such as 150 degrees Celsius for 1 - 2 hours) and then allowing them to cool and stabilize for 24 hours, the internal structure of the capacitor is re - arranged. This re - arrangement counteracts the changes that led to the capacitance decay. Interestingly, the reflow soldering process commonly used in electronic manufacturing has a similar effect. When MLCCs are subjected to the heat cycle of reflow soldering, the high temperatures can also trigger the restoration of capacitance.

 

The Role of Testing Conditions

 

It's also crucial to consider the testing conditions when evaluating MLCC capacitance. One common mistake that can lead to inaccurate readings of low capacitance is an insufficient test voltage. When testing the capacitance of an MLCC, a voltage of at least 1V should be applied across its terminals. If the applied voltage is less than this threshold, the measured capacitance value may be significantly lower than the actual value. Using a multimeter in the AC voltage range to verify that the test voltage reaches 1V can prevent misinterpreting normal - functioning MLCCs as having low capacitance.

 

In conclusion, the observed capacitance deviation in MLCCs, especially those of Class II materials, is not a sign of poor quality. It is mainly due to the material's inherent properties, such as temperature - sensitivity and natural capacitance decay over time, as well as improper testing conditions. By understanding these factors and taking appropriate measures, such as accounting for temperature effects in circuit design, performing annealing or reflow soldering when necessary, and ensuring correct testing voltages, users can make the most of MLCCs and avoid unnecessary concerns about their performance.

 

UF Capacitors MLCC Cross Reference

UF Capacitors supply generally MLCC and High Q ceramic capacitor to replace tier-1 brands like Vishay, TDK, Murata and AVX, Kemet, following cross reference FYI, 

 

Photo	Descriptiom	Vishay	TDK/Epcos	Murata	AVX	Kemet
	CT41 Chip Multilayer Ceramic Capacitors 4V to 6KV	VJ0201 Series VJ0402 Series VJ0603 Series VJ0805 Series	C1005 Series C1608 Series C2012 Series C3216 Series C3225 Series C4532 Series C5750 Series	GRM Series	0603 Series 0805 Series 1206 Series 1210 Series	C0201 Series C0402 Series C0603 Series