Effect of Metallization on the Lifetime Prediction of Mechanically Stressed Low‐Temperature Co‐Fired Ceramics Multilayers

Abstract

Multilayer ceramics based on Low‐Temperature Co‐fired Ceramics (LTCC) are gaining increasing interest in the manufacturing of high‐integrated devices for microelectronic and sensor applications. In many applications the parts are exposed to mechanical stresses, which is an important issue regarding the reliability of the device. To predict the lifetime of LTCC multilayer devices, and to extend their application range, basic mechanical data of this material are needed. In this paper metallized LTCC multilayers are investigated concerning their flexural strength, crack growth rate, and lifetime prediction. The results show that the electronic layout concerning the location of vias and metallization has a strong influence on the reliability and lifetime prediction of such co‐fired LTCC devices. Mass flow sensors for the measurement of injected fuel quantities, which were fabricated on the basis of LTCC and which are exposed to a stress level of 100 MPa, achieve sufficient lifetimes. Therefore, LTCC is an interesting material to fabricate devices, in which LTCC fulfils the requirements of a functional and structural material.

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

“…no metallization in the ceramic body) show a higher r 0 = 440 MPa (confidence interval 419-462 MPa) and a lower Weibull modulus m = 8.2 (confidence interval 6.1-11.2). Reducing the loading speed to 0.1 MPa s -1 , the values of r 0 are decreased to about 310 MPa in both cases (Dannheim et al 2005). These results demonstrate that the metallization has a low impact on flexural strength behaviour due to annealing of defects and cracks in the vicinity of the punched vias during sintering.…”

Strength reliability of 3D low temperature co-fired multilayer ceramics under biaxial loading

“…7a), most likely associated with stress concentrations, as also reported in literature for this type of architecture. 15 This could explain the relative large flaw sizes estimated with Eq. (3) for series 1 (i.e.…”

“…In this regard, the effect of metallisation on the strength distribution has been assessed in the literature using simple architectures yielding a difference not only on the strength values but also on the critical flaw size distribution (Weibull modulus) associated with the presence of vias in the design. 15 In general, the biaxial strength of ceramics can be determined by several methods, as found in Ref. 16 .…”