High Inductance Density Low-Profile Inductor Structure for Integrated Point-of-Load Converter

This paper presents a 3D integrated solution that uses a low-profile planar inductor as the substrate as one of the possible methods to integrate the magnetic component with the active component. In order to reduce the inductor size to achieve a more compact integrated converter, several low-profile inductor structures with different flux path patterns (vertical or lateral) based on low temperature co-fired ceramics (LTCC) technology are studied and compared. Some lateral flux structures are proposed to increase the inductance density for a low-profile inductor design. A 1.5MHz, 5V to 1.2V, 3D integrated buck converter with LTCC inductor substrate is designed and fabricated and Compared with a vertical flux structure, the proposed lateral flux structure can help to save around 30% of the footprint. The full load (Io= 15A) efficiency of this 3D integrated buck converter is around 87%. The power density of this integrated converter is as high as 300W/in3.

[1]  H. Reichl,et al.  Low profile power inductors based on ferromagnetic LTCC technology , 2006, 56th Electronic Components and Technology Conference 2006.

[2]  F. Lee,et al.  A Class of Ceramic-Based Chip Inductors for Hybrid Integration in Power Supplies , 2008, IEEE Transactions on Power Electronics.

[3]  Miguel J. Prieto,et al.  Design and analysis of thick-film integrated inductors for power converters , 2002 .

[4]  D. O'Sullivan,et al.  Microfabricated inductors for 20 MHz Dc-Dc converters , 2008, 2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition.

[5]  I. Batarseh,et al.  Design and Fabrication of Integrated Power Inductor Based on Silicon Molding Technology , 2007, 2007 IEEE Power Electronics Specialists Conference.

[6]  F.C. Lee,et al.  System design of a 3D integrated non-isolated Point Of Load converter , 2008, 2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition.

[7]  T. Mikura,et al.  New substrate for micro DC-DC converter , 2006, 56th Electronic Components and Technology Conference 2006.

[8]  J.A. Ferreira,et al.  Design method and material technologies for passives in printed circuit Board Embedded circuits , 2005, IEEE Transactions on Power Electronics.

[9]  E. Waffenschmidt,et al.  Integrated design procedure for printed circuit board inductors in DC-to- DC converters , 2007, 2007 European Conference on Power Electronics and Applications.

[10]  S.C.O. Mathuna,et al.  PCB integrated inductors for low power DC/DC converter , 2003 .

[11]  M. Duffy,et al.  Core Materials for High Frequency VRM Inductors , 2007, 2007 IEEE Power Electronics Specialists Conference.

[12]  K. D. T. Ngo,et al.  Modeling of an LTCC Inductor Capable of Improving Converter Light-Load Efficiency , 2007, APEC 07 - Twenty-Second Annual IEEE Applied Power Electronics Conference and Exposition.