Microfabrication process for high-frequency power-conversion transformers

A process for microfabrication of transformers for high-frequency power conversion applications is described. The process uses multilayer films of NiFe/SiO/sub 2/ magnetic material and copper coils deposited on a silicon substrate. Transformers less than 100 /spl mu/m thick are designed to handle 1.7 W each in an area 1.5 by 5.4 mm. Coil measurements confirm predicted DC and AC resistance. Applications to a 10 W, 10 MHz DC-DC power converter are discussed.<<ETX>>

[1]  P. L. Dowell,et al.  Effects of eddy currents in transformer windings , 1966 .

[2]  M. Mino,et al.  A new planar microtransformer for use in micro-switching converters , 1992 .

[3]  E. Snelling.  Soft ferrites: properties and applications , 1969 .

[4]  E. Valstyn,et al.  Performance of single-turn film heads , 1973 .

[5]  Lubomyr T. Romankiw,et al.  Batch fabrication of thin film magnetic recording heads: A literature review and process description for vertical single turn heads , 1975 .

[6]  Fabrication of a thin film head using polyimide resin and sputtered Ni‐Fe films , 1982 .

[7]  C. Brucker,et al.  A magnetic head for 150 MHz, high density recording , 1990 .

[8]  Kiyohito Yamasawa,et al.  High-frequency operation of a planar-type microtransformer and its application to multilayered switching regulators , 1990 .

[9]  Development of a 48‐turn thin‐film head , 1990 .

[10]  Tomasz Jagielinski,et al.  Materials for Future High Performance Magnetic Recording Heads , 1990 .

[11]  O. Kohmoto,et al.  Recent development of thin film materials for magnetic heads , 1991 .

[12]  A new horizontal thin film head , 1991 .

[13]  M. Mino,et al.  A new planar microtransformer for use in macro-switching-converters , 1991, PESC '91 Record 22nd Annual IEEE Power Electronics Specialists Conference.

[14]  Masahiro Yamaguchi,et al.  Characteristics and analysis of a thin film inductor with closed magnetic circuit structure , 1992, 1992. Digests of Intermag. International Magnetics Conference.

[15]  Recent Development of Thin Film Materials for Magnetic Heads , 1992 .

[16]  H. Reichl,et al.  Fabrication of high depth-to-width aspect ratio microstructures , 1992, [1992] Proceedings IEEE Micro Electro Mechanical Systems.

[17]  K. Yamaguchi,et al.  Characteristics of a thin film microtransformer with circular spiral coils , 1993 .

[18]  K. Yanagisawa,et al.  Microtransformer with monolithically-integrated rectifier diodes for micro-switching converters , 1993, Proceedings of IEEE Power Electronics Specialist Conference - PESC '93.

[19]  Charles R. Sullivan,et al.  Microfabrication of transformers and inductors for high frequency power conversion , 1993, Proceedings of IEEE Power Electronics Specialist Conference - PESC '93.

[20]  Hidetoshi Matsuki,et al.  Load characteristics of a spiral coil type thin film microtransformer , 1993 .

[21]  D. Tang,et al.  Stable encapsulation structures for Permalloy films , 1994 .