Lifetime prediction for mechanically stressed low temperature co-fired ceramics

The porosification of fired LTCC substrates by applying a wet chemical etching procedure

“…12,13 In this context, reliability in respect to mechanical strength is an important issue, especially when the LTCC needs to fulfil not only the requirements of a functional, but also of a structural material subjected to high mechanical load. 14,15 Besides these applications, LTCC is most favourably used as substrate for micromachined devices and systems operated at high frequencies typically ranging up to the microwave region. Although there are also other types of high-density, multilayer substrates available, based on organic laminates, further outstanding features of the LTCC for this field of application are the excellent thermal conductivity compared to organic materials and a coefficient of thermal expansion close to that of silicon.…”

Evaluation of electron beam welding technique for the integration of robust sensor elements into high-pressure automotive systems

“…In the model the arrows indicate the areas pressure loaded with 150 MPa whereas the triangle-shaped symbols mark regions where all DOF are fixed. From ultrasonic measurements reported in a recently published study the Young's modulus of the LTCC was determined to E = 153 GPa and the Poisson's ratio m = 0.17 was taken from the data sheet published by DuPont for the LTCC tape 951 (Dannheim et al 2004). From the FEM calculations the stress value at all nodes is evaluated according to the principal normal stress hypothesis due to the brittle nature of the glass-ceramic material.…”

Influence of temperature and humidity on the strength of low temperature co-fired ceramics

“…Such a phenomenon has been also reported in LTCC or in SOFC materials loaded under mechanical stress, especially in humid environments. [11][12][13][14][15] Among the different models proposed to describe the crack growth in these materials, a direct chemical attack of the environment on the crack tip seems to have the strongest experimental support. 7,9 Depending on the crack growth rate and environment, different mechanisms of SCCG exist, which can be recognised by different slopes in a double logarithmic plot of the v-K I curve, 6 where v represents the crack growth rate and K I the applied stress intensity factor at the crack tip.…”