The Study Of Water-based LTCF Slurry In The Field Of Inductive Components

With the rapid development of electronic information industry，the final productsemerge endlessly with the new design, new idea and new feature. And the trend of theelectronic devices has been developing constantly to miniaturization, integration,high-power and multi-function. Currently, the technology of Low Temperature Co-firedCeramics (LTCC) which is used to develop new passive integration devices becomes tobe a research focus, in which Low Temperature Co-fire Ferrite (LTCF) passiveintegration technology has already become one of the most potential techgologies. Themain raw and process materials used in LTCF, however, are non-water-based oneswhich are of toxic and harmful both to the human beings and to the environment in theconcept of energy saving and environmental protection. Therefore, concerned with therising cost of chip components and green manufacturing, the development of thelow-cost water-based process becomes the research mainstream of the LTCFapplications.In this paper, LTCF low cofired ferrite and NiZn ferrite material are studied as ourresearch objects. Firstly, the characteristics of the powder dispersed in water areinvestigated and a good dispersibility is obtained through a set of process optimizationon the water-based slurry. Secondly, by experimental optimizing on the slurrycomposition, the water based NiZn ferrite cast slurry is successfully prepared to meetthe cast molding requirements. Finally, the water-based NiZn ferrite cast slurry is usedto produce multilayer chip inductor beads and the final products are verified to matchthe industrial requirements, which are the dimension of bead is adapt to IEC1608, thenominal value of inductance is1.0μH and the nominal value of impedance Z is600ohms. The results of this study could give its contributions in the field of water-basedLTCF slurry inductive components.The main conclusions are as follows:(1) The dispersibility of the powder dispersed in water is studied. By using ionicdispersant ammonium polyacrylate, we have obtained the best dispersion and the bestconcentration. For the Ni-Zn ferrite powder, the optimum dispersant concentration is 0.6%.(2) The solid content and the binder content are studied. The experimentaloptimum solids content and the binder content is54.5%and6.5%, respectively.(3) The slurry defoaming techniques are studied such as the mechanicalvacuum-defoaming and stirring defoaming, and the best technique without pores in thestrips is obtained by using a composite defoaming method.(4) The shape of the sintered magnets is not stable enough. This might due to thefacts that during the performance of the flan the flan has not yet dried, and that duringthe molding or cutting process the temperature is much higher than its common level.There might be another reason that the operating process window of the the water-basedslurry molding is too small.(5) Based on the optimization of various process parameters, the performance ofsize1608inductor produced from our water-based slurry is the same as that of theinductor beads produced on the organic system, and the cost of the products producedon the temporary adhesive system is reduced significantly. This means that thewater-based technologies can be applied in the inductive components of LTCF.