**1. Introduction**

Creation of a sound bond of ceramic materials mutually or in combination with metal depends on the fact that whether a close contact to atomic distance is formed on the but surface and

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

whether ceramic material is wetted with the metallic solder. Wetting the ceramics with a metallic solder is an essential precondition for soldered joint formation.

Several ways may be used for ensuring the wettability of a ceramic material. For example, the deposition of solderable coating on ceramic material is often employed.

However, more modern methods seem to be the application of solders which are alloyed with some active metal such as Ti, In, Si, Al, Mg and/or lanthanides, which exert a strong chemical affinity to oxygen.

The first group comprises the active solders based on Sn or Sn-Ag, which may contain from 1.5 to 4 wt.% Ti. Another group of solders, which may wet the ceramic material, consists of solders alloyed with a small amount of lanthanides, for example, La, Ce and so on. The content of lanthanides usually varies from 0.5 to 2 wt.%. The last group are the solders containing indium in the amount from 20 to 100 wt.%. However, solving the mentioned issue still involves the requirement to ensure a joint that should resist the effects of residual stresses formed owing to different coefficients of thermal expansivity of metal and ceramics, which usually exerts much lower expansivity. This condition is most essential from the viewpoint of ensuring the reliability of ceramics/metal joints [1].
