Create Stable, Reliable, And Efficient Tantalum Capacitors

Low BDV indicates defects in the dielectric and, therefore, a high probability of failure in the field. High BDV indicates flawless dielectric. Figures 4 and Figure 5 show the distribution of screening voltage within a lot of 100-µF/16-V, X-case solid Ta capacitors and the resulting data, respectively. Screening voltage correlates with actual BDV in individual capacitors.

As per the example, about 95% of the distribution lies in the narrow range of voltages while 5% of the distribution spreads out toward low voltages. DCL readings in all parts were much lower than the DCL limit for this rating. According to data in Figure 5, there’s no effect on DCL readings during the screening, confirming the non-destructive nature of the screening process.

Additionally, Figure 6 demonstrates the results after accelerated life testing on screened capacitors versus non-screened capacitors. We observe failures at power-on in non-screened capacitors at an early stage during this accelerated test. In contrast, screened capacitors do not show any early failures, and their time-to-failure distribution is uniform.

CONCLUSION
Crystallization-preventing techniques provide low and stable DCL as well as higher volumetric efficiency for Ta capacitors with mid-range and high working voltages. Teaming with the unique breakdown simulation screening process, the capacitors demonstrate exceptional reliability. In addition, these anode improvement and testing techniques apply to both surface-mount tantalum and wet tantalum capacitors to provide high reliability and stable leakage current characteristics.