Study On Power Loss Characteristics And Application Of Low-temperature-fired NiCuZn Ferrite Materials

As a soft magnetic material,NiCuZn ferrite is widely used in various fields due to its high resistivity,saturation magnetic induction and good high frequency performance.With the rapid development of electronic components in the direction of miniaturization and multi-function,higher requirements are also placed on the performance of NiCuZn soft ferrite such as power loss.Low temperature co-fired ceramic（LTCC）technology can well meet the needs of device miniaturization and integration.In order to better match with LTCC technology,NiCuZn ferrite must be sintered at low temperature.Today,lowpower and low-temperature sintered NiCuZn ferrite materials have become the key to the development of LTCC devices.In this thesis,NiCuZn ferrite was prepared by low temperature sintering at 900℃.The effect of Cu substitution on the soft magnetic properties of Ni0.6-xZn0.4CuxFe1.98O4（x=0.1～0.325）ferrite with low content of Bi2O3（0.25wt%）and high content of Bi2O3（1 wt%）was investigated.By comparison,it is found that in the doping mode of low Bi2O3,the overall grain growth is smaller and uniform.When the Cu content is low,the density of the ferrite is very low.When the Cu content reaches a certain level,the density of the sample is only will increase high enough.In the high Bi2O3 doping mode,the overall density of the ferrite is relatively high in the entire Cu substitution range,and the average particle size of the ferrite is relatively large.When the densification degree of the two groups of samples is good,the initial permeability,quality factor Q,saturation magnetic induction Bs value and even the applicable frequency of the low Bi2O3 doped sample are better than those of the high Bi2O3 doped sample,but its properties are more sensitive to the change of Cu content.Based on a group of samples with better overall soft magnetic properties（Cu content of 0.275,low Bi2O3 doping）,this thesis continues to dope SnO2,TiO2,Co2O3 three oxides to further improve the power loss performance of NiCuZn ferrite.Experiments show that the density of the samples increases with moderate doping of all three oxides.For the samples doped with SnO2,at the doping amount of 0.1wt%SnO2,the samples obtained the lowest loss value,the highest saturation magnetic induction intensity and density.For the samples doped with TiO2,under the doping amount of 0.2wt%TiO2,the sample has the highest resistivity and the lowest loss value,but under other doping amounts,the resistivity of the sample is lower and the loss value also increases,The effect of reducing power consumption is not significant.For the samples doped with Co2O3,under the doping amount of 0.3wt%Co2O3,the samples obtained higher density and saturation magnetic induction,and always had the lowest power loss,and the reduction of power loss was very obvious.After comparing all doped samples,the thesis selects NiCuZn ferrite doped with 0.3wt%Co2O3 and 0.25wt%Bi2O3 as the magnetic core material,and uses HFSS software to design and simulate the LTCC transformer.Finally,a LTCC transformer with excellent performance was successfully obtained.