Inter-diffusion between NiCuZn-ferrite and LTCC and its influence on magnetic performance

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

“…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]. This may be due to the formation of copper-rich precipitates during NiCuZn ferrite sintering attributed to the sintering process being faster than oxygen diffusion from the outside into the pores [19].…”

“…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.…”

“…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. They found that Cu ions from the ferrite can diffuse into LTCC at a distance of around 120 m and Mg and Al ions from LTCC also diffuse into the ferrite for a short distance during co-firing.…”

Effects of solid-state reaction temperature on the activation energy and DC-bias superposition of NiCuZn ferrites based on master sintering curve

“…Ferrites are the most sought materials in the fabrication of electronic devices due to their desirable electrical, magnetic and dielectric properties. [1][2][3] In the fabrication of MLCI, NiCuZn ferrites are used because of the excellent magnetic properties in the high frequency, and can be sintered below the melting point of Ag (around 961°C). NiCuZn ferrites are stacked alternately with the conducting inner electrode, usually silver paste, and then co-fired to obtain monolithic structure.…”

Enhanced ferromagnetic properties of low temperature sintering LiZnTi ferrites with Li2O–B2O3–SiO2–CaO–Al2O3 glass addition

“…However, LiZnTi ferrites do not meet the basic requirements with regard to sinterability for LTCC technology since they have relatively high sintering temperature [5][6][7]. The addition of borosilicate glasses is an effective way to decrease the firing temperature in LTCC materials [8][9][10][11][12][13][14]. Those glasses exhibit a softening point of $700°C and have a crucial influence on the viscosity of the melt during the firing as described by the Mauro-Yue-Ellison-Gupta-Allan (MYEGA) equation [15]: log 10 gðTÞ ¼ log 10 g 1 þ ð12 À log 10 g 1 Þ Tg T exp m 12Àlog 10 g 1 À 1 h Tg T À 1 i ; where T g is the glass-transition temperature, defined by log 10 gðT g Þ ¼ 10 12 Pa s [16], m is the liquid fragility index, defined by m ¼ @log 10 gðTÞ @ðTg=TÞ T¼Tg [17].…”