The rise of 5G, artificial intelligence, and other applications drives the demand for planar inductors based on PCB processes, due to the advantages of compatible processes, flat shapes, high power densities, reduced volumes, etc. In this paper, six kinds of soft magnetic encapsulation materials (SMEs) were selected to prepare planar dual-layer spiral inductors (PDSI). The actual PDSI device, as well as the six kinds of SMEs, were then processed. Based on the tested relative permeability of SMEs, FEM models were built and calibrated through the actual PDSI structures. Furthermore, FEM models of single-layer, double-layer, and multilayer inductors were established respectively, with analysis of the differences in magnetic properties. The results reveal that both Land Q of the PDSI exhibit a positive linear correlation with the relative permeability of the SMEs, and SMEs with high permeability limit the magnetic leakage. The multilayer inductor could achieve similar Land Q values with a smaller area compared with the planar inductor. However, the increase in thickness limits their application in thin devices. The models can be adjusted to match the SME properties and size parameters of the actual manufacturing process, contributing to simplified calculations for inductor design and performance analysis. Based on such analysis, the planar inductor designs based on in-house SME and PCB-compatible processes are adjusted for high-frequency applications. ... Read more

With the development of 5G communication technology and the rise of power semiconductors, the switching frequency of the circuit keeps increasing, which pushes for miniaturization of power modules and related components. Therefore, in this paper, a one-step molding technology was proposed for a DC/DC buck converter power module. We proposed a method of using Soft Magnetic Powder filled Epoxy (SMPE) adhesive as a molding material to encapsulate a power module, which is a DC/DC buck converter power module contains several passive components, 1 power inductor, and a high-efficiency switching regulator with two integrated N-channel MOSFETs. On the basis of Finite Element Method (FEM), models were firstly established with component level moldings and checked with actual module samples for calibration. Based on the calibrated model, inductors without component level molding were then simulated. SMPE with 4~7μm insulated carbonyl ferrous powder were prepared and measured the magnetic relative permeability. Such material was investigated to pot the whole power module as a one-step molding, instead of separate molding for the power inductor and the power module. After that, thermal analysis and inductance were calculated and compared. ... Read more