1 . The definition of soft terminal MLCC and market demand

 

In the field of electronic components, multilayer ceramic capacitors (MLCC) are hailed as the "cornerstone of the electronics industry". Their characteristics such as miniaturization, high capacitance, and low ESR make them widely used in various electronic devices. However, in recent years, with the rapid development of fields like 5G communication, new energy vehicles, and industrial automation, the reliability issues of traditional MLCCs in extreme temperatures, mechanical vibrations, or PCB bending scenarios have gradually become prominent. The emergence of soft termination MLCC provides an innovative solution to this problem and has become the "invisible guardian" for high-reliability design.

 

Figure 1: Failure Rate of MLCC

 

As shown in Figure 1, from the statistical results, it can be seen that among the failure modes of MLCC, the failure mode caused by mechanical stress accounts for a relatively high proportion, reaching approximately 60%. This is a traditional pain point of MLCC and there is a great demand for improvement.

 

Figure 2: Mechanical Stress Failure Mode

 

As shown in Figure 2, the mechanical stress failure mainly occurs when the deformation of the PCBA board is transmitted to the connection point of the MLCC terminal. The traditional MLCC hard terminals have weak stress resistance capabilities, which leads to cracks in the ceramic body at the terminal, thereby causing the MLCC to fail. Soft terminal MLCC is an electronic component specifically designed to address the failure caused by mechanical stress. Its core lies in the flexible design of the terminals. Through material and structural innovations, soft terminal MLCC significantly improves the reliability of electronic devices in harsh environments. It is increasingly being selected by people in automotive and industrial applications.

 

2. Process differences between soft terminal MLCC and general MLCC

The soft terminal MLCC has additional processes of secondary encapsulation and curing compared to the general MLCC. The function of this process is to create a resin end layer through secondary encapsulation, and then cure the resin layer at a low temperature to achieve the addition of flexible materials at the MLCC end, thus completing the manufacturing process of the soft terminal MLCC.

 

3. Structural differences between soft terminal MLCC and general MLCC

 

Comparison of Two Types of MLCC Terminal Structures 

           

 

 

Note: The structural layers and materials from the inside out

 

Figure 3: Cross-sectional Structure of Soft Terminal MLCC

 

The soft terminal MLCC end cap is a four-layer metal/resin structure, consisting of three layers of hard metal end caps and one layer of soft conductive resin end cap. When the PCBA bends, vibrates, or the product is in an environment with temperature changes, its ability to resist the stress from the environment on the MLCC is significantly improved compared to general MLCCs. This can effectively reduce the risk of insulation resistance reduction and short circuits caused by cracks in the MLCC end cap.

 

Figure 4: General MLCC Cross-sectional Structure

 

The general MLCC terminals consist of three metal layers, all of which are hard metal layers. When the PCBA is bent, vibrates, or the product is in an environment with temperature changes, the ability of these terminals to resist the stress from the environment on the MLCC is lower compared to the soft terminal MLCCs. This makes them more prone to cracking at the MLCC terminals, leading to a decrease in insulation resistance or short circuits.

 

4. Advantages of Soft Terminal MLCC

 

 

Stress absorption: The flexible end cap (conductive resin layer) can deform and buffer, reducing the mechanical stress transferred to the ceramic layer.

Anti-thermal expansion mismatch: Mitigates the thermal stress caused by the difference in CTE between the ceramic and the PCB substrate (such as FR4).

 

 

5. Standard Differences between Soft Terminal MLCC and General MLCC

 

 

 

Figure 5: Test Method for Bonding Strength of Terminal Electrodes

 

As shown in Figure 5, the method for testing the bonding strength of the end electrodes is to install the sample to be tested on the test substrate, apply a force in the vertical direction, and measure the capacitance (test standard: the bending degree of the soft terminal MLCC is ≥ 3mm; the bending degree of the general MLCC is ≥ 1mm).

 

Comparison test of soft terminal MLCC and general MLCC

 

Testing method

Weld the MLCC onto the test board, then bend the PCBA board to the maximum level at a speed of 1mm/s.

Remove the MLCC after testing and conduct DPA section analysis to check if there are any abnormalities in the internal structure.

 

 

From the analysis of the cross-sectional structures after the extreme bending tests of the soft-terminal MLCC products and the general MLCC products, it can be concluded that when the terminals of the MLCC are subjected to the extreme mechanical stress, the soft-terminal MLCC products have a stronger ability to resist mechanical stress compared to the general MLCC products. Under the stress conditions where the general MLCC products develop mechanical cracks, the soft-terminal MLCC products release the stress through the flexible terminals, protecting the ceramic body and reducing the risk of mechanical cracks.

 

 

Soft terminal MLCC product market application

 

EYANG Technology has launched a variety of series of soft terminal MLCC products for automotive, industrial and general applications. These products are suitable for various environmental requirements and end product applications. The product packaging includes various sizes such as 0402 to 2220. The application temperature ranges from -55℃ to 150℃ for various environmental applications. The capacitance ranges from 0.1pF to 220μF in multiple gradient levels. For more details, please contact our sales staff or technical support personnel.