Research On DC-bias-superposition Ferrite Material And Multilayer Chip Inductor Based On LTCC Technology

In recent years,electronic devices have been moving in the direction of convenient carrying and complete functions,which brought us to the design of the circuit to small size,multi-functional.In order to increase the density of the circuit,the most direct measure is to reduce the size of the electronic component.In switching power supply designs,Chip inductors are often used,and which are not only required to meet both low loss and miniaturization,the multilayer chip high-power inductors need to be stable and reliable under the working condition of DC-bias-superposition.In order to meet the requirements of the above two aspects,the most critical point is to improve the properties of the matrix material and structure of the inductor.Therefore,the main work of this paper is to develop the ferrite material with excellent performance,and use the material to design the chip inductor and it is applied to the switching power supply circuit.The chip inductor in the switching power supply circuit is tested for its performance parameters to verify the feasibility of the material.Firstly,in terms of materials,NiCuZn ferrite is selected as the substrate material.This paper mainly researched the effects of ZnSiO₄,CaCO₃,Al₂O₃ and Nb₂O₅ were doped about the DC-bias-superposition characteristics of the sample.In the experiment,different amounts of dopants were doped into the same master formulation to find samples with the same magnetic permeability,and then the best performance dopants were found by comparison.The results show that the four groups of doping reacted fully with NiCuZn ferrite,and exhibited single spinel phase.For all samples doping,their electromagnetic properties have similar trends with different doping amounts.As the amount of doping increased,the grain size of the sample gradually decreased,the pores increased,and the sintered density gradually decreases.These factors lead to a decrease in the initial permeability of the sample.Studies have shown that the Bs,?35?B and Hc of the material has an influence on the DC-bias-superposition characteristics.However,in general,the material Hc has the greatest influence on the characteristics of large DC current resistance.In the experiment,the four doping of ZnSiO₄,CaCO₃,Al₂O₃ and Nb₂O₅ have an effect on the coercive force of NiCuZn ferrite.Therefore,the four doping have improved DC-bias-superposition characteristics of low-temperature sintered NiCuZn ferrite,but the difference is that some doping such as Al₂O₃ and Nb₂O₅ are easier to accumulate at the grain boundary than ZnSiO₄ and CaCO₃.Therefore,it will hinder the growth of crystal grains,and has a greater influence on the coercive force of the material,thereby being more effective for improving the DC-bias-superposition characteristics of the material.Finally,through experimental comparison,we found that under the same magnetic permeability?initial permeability is 70?,the H_70%of the four doped samples of ZnSiO₄,CaCO₃,Al₂O₃ and Nb₂O₅ are 673.2 A/m,783.6 A/m,820.1 A/m and 839.6 A/m respectively.Therefore,the material with Nb₂O₅ doped has the best performance.The material with Nb₂O₅ was used as the base material of the substrate with inductor.Its design goal is that the inductance satisfies 0.6±20%?H,the work frequency is 1 MHz,rated current value is higher than 10 A and the DC resistance satisfies 0.01±25%?.The test results show that even though we didn't achieve our goals.However,the material of Nb₂O₅ doping can speed up the inductor to the DC-resistant,small-size target.