Interfacial reaction of LTCC/NiCuZn ferrites in multilayer composites

Abstract

In this study, the cofiring behavior and interfacial interaction between a low dielectric constant LTCC material and NiCuZn ferrites at 900°C were studied using XRD, dilatometer, SEM, EPMA and TEM. It was observed that the delamination occurred at the interface between LTCC and NiCuZn ferrites added with Bi2O3. It may be due to the Bi enriched at the interface and diffused into LTCC, which shifted the densification curve of LTCC towards low temperature, and hence resulted in the shrinkage mismatch between LTCC and NiCuZn ferrites.

Ag precipitation at the free interface of multilayer NiCuZn ferrites/LTCC components

“…The NiCuZn ferrite is composed mainly of nickel, copper, zinc and iron. In our previous study [10], the chemical composition across the interface between NiCuZn ferrites and LTCC after cofiring at 900 • C for 2 h was investigated and observed that no obvious element inter-diffusion of Ni, Zn, Fe, Al and Si was observed at the interface. Only a small concentration of copper ions from the ferrite can diffuse into the LTCC at a distance of around 10 m, which is consistent with the observations of Lee et al [11].…”

“…The cofiring behavior and interfacial structure of LTCC/NiCuZn ferrite laminates were recently investigated [2,[10][11][12][13]. In our previous study large pores and air gaps occurred at the interface between NiCuZn ferrites containing Bi 2 O 3 and LTCC after cofiring at 900 • C for 2 h. This is due to widening of the shrinkage mismatch between NiCuZn ferrites and LTCC resulting from Bi 2 O 3 in NiCuZn ferrites diffusion into LTCC.…”

“…In our previous study large pores and air gaps occurred at the interface between NiCuZn ferrites containing Bi 2 O 3 and LTCC after cofiring at 900 • C for 2 h. This is due to widening of the shrinkage mismatch between NiCuZn ferrites and LTCC resulting from Bi 2 O 3 in NiCuZn ferrites diffusion into LTCC. This leads to the formation of a new Bi-B-Si glass with a lower glass transition temperature and viscosity sandwiched between LTCC and NiCuZn ferrites [10]. Lee et al [11] studied the interdiffusion between NiCuZn ferrite and LTCC during co-firing.…”