Based On Ltcc Technology Nicuzn Ferrite Materials And Anti-emi Filter Development

Developing new function material, farther miniaturization of electric devices, anti-electromagnetism interfere(EMI),the three are all the problems starve for solution. Basing LTCC technology, developing low temperature co-fired ferrite (LTCF) material, multilayer chip inductors (MLCI) and anti-EMI filters is one of the shortcut to solve the three problems. In this dissertation, the investigations were aim on the theories, technics and applications of the LTCF and chip components designing. The research mode that combined material preparation, technology of low temperature co-fired ceramic(LTCC) manufacture,designing components and devices was adopted to develop high performance low-fired NiCuZn ferrite, which were very suitable to produce multilayer chip inductors and LTCC anti-EMI filters.In the part of experiments investigations, one kind of applicable low temperature co-fired NiCuZn ferrite material was prepared by the oxide method(solid-phase reaction ). The influences of compositions on the sintering behaviors, microstructures and magnetic properties of the ferrite were investigated. It was confirmed that 10mol% CuO content was appropriate to give attention to both low-fired characteristic and good magnetic properties of the NiCuZn ferrite. Effect of adding V2O5, SiO2 and Bi2O3 on the electromagnetic properties of NiCuZn ferrite was investigated, it showed that adding these dopants can reduce the sintering temperature of NiCuZn material evidently.The effect of adding different combinations was studied. It was confirmed the optimal additives were"Bi2O3+Co2O3". The improvement on the electromagnetic properties of NiCuZn ferrite by controling such technologic of milling, calcining and quenching after calcining were studied also. Finally, the high performance NiCuZn material was prepared on the condition of CuO content in the main formula is 10mol%,adding"1.0wt%Bi2O3 + 0.2wt%Co2O3", milling for 24h,calcining at 800℃, using fast quenching after calcining,sintering at 900℃,with the initial permeability(μi)=120±15%, Q≥180, courier temperature(Tc)≥180℃, average granularity of the ferrite powder is 0.7μm.In the part of devices research and LTCC manufacture, the Ansoft-HFSS and Agilent-ADS software was adopted to creating three-dimensional model and doing the electric and magnetic field simulation for the buried inductors and capacitors basing the LTCC technology. Effect of various of parameters of models on the properties of inductors were studied, and the calculate formula between the inductance and circles(N) was deducted in the circumstance of given parameters: Leff=116.25×N1.67nH. In addition, technology of LTCC manufacture was studied particularly, the key technology in the technologic flow and some experience in the actual designing and manufacture were presented also. Lastly, the prepared NiCuZn ferrite was chosen to produce the multilayer chip inductors and anti-EMI filters by adopting LTCC technical line. It was confirmed that the produced inductance values were lower than the forecast, which was mainly due to debasement of the permeability. However, the relationship between inductance values and turns of the coils was coincident with the forecast; the anti-EMI filter prepared with the size is only 0805(80mil×50mil viz,2.0mm×1.3mm),cut off frequency is 10MHz,ripple within the passband belows 0.5dB, attenuation exceed 40dB at 40MHz..