**3.3 Analysis of Al2O3-SnAg3.5Ti4(Ce,Ga) joint**

**Figure 18** shows the interface of Al2O3-SnAg3.5Ti4(Ce,Ga) joint. A continuous reaction layer containing Ti was observed in the interface of Al2O3- SnAg3.5Ti4(Ce,Ga) joint. This reaction layer allows the wetting of ceramic material and the tin-silver matrix of solder guarantees the desired strength and sufficient plastic properties of soldered joint to compensate the strains and stresses formed during cooling down. Slightly increased concentration of cerium was also observed in the joint interface. The presence of gallium and/or its effect upon bond formation was not observed (**Figure 19**).
