The design and fabrication of multilayer chip LC filter with a modified structure by LTCC technology

To solve the densification and thermal expansion mismatch problems, this paper proposes a novel method based on the simulations of the chip LC filter with the cut-off frequency at 10 MHz with the aid of HFSS software. The difference of thermal expansion between ceramic and ferrite can be trailed off in some degree, because the ferrites layers were put in the middle of ceramic layers. The materials are adopted as ULF140 ceramic and LSF400 ferrites bought from Ferro Company. And the filter samples are successfully prepared by LTCC process. The interfacial conditions of the sample are systemically investigated by SEM and microcosmic results show that the heterogeneous layers are in good connection, with no evidence of cracks or delaminations. The electronic performances of the filter samples are carried on Agilent 8722 ES equipment with the cut-off frequency is at 9.5 MHz and the attenuation is beyond 25 dB. All the measurements indicate that the method is very effective for the fabrication of multilayer chip LC filters.