An improved microchip thin film transformer formed by vacuum evaporation and sputtering

A microchip thin film transformer which is composed of an I-shaped [CoZrNb/ SiOx](m) magnetic layer and wound with Cu thin film coils fabricated by usi ng a mask vacuum evaporation and sputtering composited process has been inv estigated. Comparing the CoZrNb core with [CoZrNb/SiOx](m) core of thin fil m transformer, it is shown that the multilayer thin films have more advanta ges than a single magnetic layer in their of soft magnetic properties, espe cially the permeability (mu) and coercivity (H-c). The microchip transforme r has a relatively high inductance of 0.4-1.0 muH for a ratio of primary tu rns to secondary coil turn's of 3 : 1 and 3 : 2, and has a high e value of 4-12. The thin film transformer can be operated in an integrated micro-swit ching converter at a frequency between 1 kHz and 10 MHz. (C) 2001 Elsevier Science Ltd. All rights reserved.