Power Conversion Module using LTCC substrate Interconnected to Power Inductor with Low DCR

In this paper, a power inductor embedded pattern with multi-via is proposed to achieve the lower DCR. Also, the low temperature co-fired ceramic (LTCC) substrate for the power conversion module was fabricated to be interconnected with a proposed power inductor. A proposed power inductor can be interconnected to the bottom side of the LTCC substrate. Two types of power inductors were fabricated to compare electrical properties. One is with the single-stack multi-via pattern (SMP) and the other is with the dual-stack multi-via pattern (DMP). The DCR, inductance at the frequency of 1 MHz, and Q-factor at the frequency of 1 MHz for the fabricated inductor with SMP were 17.82 mΩ, 3.21 μH and 42.19, respectively. On the other hand, that of the fabricated inductor with DMP were 12.49 mΩ, 3.3 μH, and 56.77, respectively. Compared to the fabricated inductor with SMP, the inductor with DMP shows lower DCR and higher Q-factor while having a similar inductance. A LTCC based DC-DC converter as the power conversion module was designed to be interconnected with proposed inductors. A DC-DC converter with switching frequency of 1 MHz has input voltage of 12 V, output voltage of 5 V, and rated power of 35 W. The efficiency of the converter with SMP inductor at 35 W was 92.41 % and that of the converter with DMP inductor was 93.79 %. A proposed inductor was designed to minimize DCR and to improve the stability of fabrication. Based on the measured results, it is demonstrated that the DCR is decreased by a proposed structure. This is due to the multi-via pattern in the proposed inductor. It is also proved that a proposed inductor is very suitable for improving the efficiency of the power conversion module.