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Automotive Grade MLCCs - AC Series
Yageo extended its automotive grade (AC Series) multilayer ceramic capacitors (MLCC). The ranges cover both class I NPO/X8G and class II X7R/X8R up to 4.7 micro farad capacitance and 6.3V to 1kV rated voltage with case sizes from 0201 to 1812(inch). This range extension makes Yageo completely competitive in automotive passenger compartment applications such as audio/video systems, navigation, remote vehicle control, lighting and other infotainment devices. Yageo treats AEC-Q200 criteria as the basic quality requirements. Approaches to reach an even higher quality level include high quality raw materials, special construction design, and dedicated production line, tightened processing control, entire in line and outgoing automatic checks, with all adopted on top of existing production standards.
To be more robust, the internal construction design for the AC grade has been evaluated. A different inner electrode structure and modified dimensions of the cover plate and margins were implemented. As mentioned, the starting material’s quality is well designed and controlled. For example, the particle size distribution of the powder used for the AC series production is narrower than that used for commodity grade. With smaller deviations in all the MLCC processing stages, better quality can be obtained.
Automotive Grade MLCC with Soft Termination – AS series
The range was also extended with soft termination (AS-Series) multilayer ceramic capacitors (MLCCs). These AS ranges are class II X7R up to 4.7 micro farad capacitance with case sizes (inch) 0603 to 1210. Continuous quality improvements and assurances, can solve the cracking issue caused by excessive mechanical stress and thermal fatigue.
The soft termination capacitors are designed with the insertion of a layer of conductive polymer-Ag into the normal termination structure in order to provide extra elasticity, thus improving the ability to resist cracking and resulting in overall product reliability.
There are two viewpoints on high reliability MLCCs, Macro-structure and Micro-structure. To be more robust, the internal construction design for the AS has been evaluated. For example, some low capacitance items may apply different inner electrode structure and modified dimensions of cover plate and margins to enhance mechanical and electrical performance. In contrast with the macro-structure, a good micro-structure requires more effort in material design and processing control. A good micro-structure for high reliability MLCC should therefore be uniform in grain size and core-shell structure.
Conclusion
Comprehensive and continuous Statistical Process Control has been installed in Yageo’s MLCC production lines. This provides an effective and instantaneous response in production status, and modifications can then be made immediately to ensure the quality. After all these types of approaches have been applied to the AC and AS series MLCCs, high reliability performance can be reached. This reliability level is much higher than that required by AEC-Q200. Production part approval process (PPAP) documents are ready for all AC and AS series items. The series are RoHS compliant also, and with improved thermal and mechanical robustness. This offers customers a wider variety of choices and solutions in order to meet various application demands and requirements.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.