**3.6 Analysis of Cu-SnTi2 joint**

**Figure 24** shows the interface of SnTi2-Cu joint. A continuous layer of reaction elements is formed in the interface of SnTi2 solder and copper by dissolving Cu in

**41**

**Figure 25.**

*Soldering by the Active Lead-Free Tin and Bismuth-Based Solders*

*Microstructure of interface of Al2O3-SnTi2 joint (SEM) + concentration profiles of elements.*

Sn matrix. We suppose the formation of similar Cu6Sn5 and Cu3Sn phases as in the case of SnAg3.5Ti4(Ce,Ga) solder. The thickness of layer of intermetallic compounds depends on the level of soldering temperature and partially also on the dwell time at soldering temperature. Based on the records from EDW analyses, it may be

*Microstructure of interface of Cu-SnTi2 joint (SEM) + concentration profiles of elements.*

*DOI: http://dx.doi.org/10.5772/intechopen.81169*

**Figure 23.**

**Figure 24.**

*Microstructure of interface of Cu-SnTi2 joint (SE).*

**Figure 22.** *Microstructure of interface of Al2O3-SnTi2 joint (SE).*

*Soldering by the Active Lead-Free Tin and Bismuth-Based Solders DOI: http://dx.doi.org/10.5772/intechopen.81169*

#### **Figure 23.**

*Lead Free Solders*

**Figure 21.**

It was found out that Ti does not contribute at all in bond formation and its effect upon bond formation was unobservable. Ag element did not exert any significant interaction with the parent material; however, its presence in the interface was observed. The Ce and Ga elements occurred in the boundary in such low amounts

**Figure 22** shows the interface of SnTi2-Al2O3 joint. From the map of planar distribution of elements, it is obvious that the active Ti element significantly contributes in bond formation. It forms a continuous reaction layer, similarly as in the case of SnAg3.5Ti4(Ce,Ga) solder. This reaction layer is formed by Ti reaction with oxygen from ceramics at formation of titanium oxides, which alter the surface tension of ceramics and thus allow its wetting by solder. The effect of other elements

**Figure 24** shows the interface of SnTi2-Cu joint. A continuous layer of reaction elements is formed in the interface of SnTi2 solder and copper by dissolving Cu in

(except Ti) upon bond formation was not observed (**Figure 23**).

*Interface of Cu-SnAg3.5Ti4(Ce,Ga) joint (SEM) + concentration profiles of elements.*

that they could not be identified at all.

**3.5 Analysis of Al2O3-SnTi2 joint**

**3.6 Analysis of Cu-SnTi2 joint**

*Microstructure of interface of Al2O3-SnTi2 joint (SE).*

**40**

**Figure 22.**

*Microstructure of interface of Al2O3-SnTi2 joint (SEM) + concentration profiles of elements.*

#### **Figure 24.**

*Microstructure of interface of Cu-SnTi2 joint (SE).*

#### **Figure 25.** *Microstructure of interface of Cu-SnTi2 joint (SEM) + concentration profiles of elements.*

Sn matrix. We suppose the formation of similar Cu6Sn5 and Cu3Sn phases as in the case of SnAg3.5Ti4(Ce,Ga) solder. The thickness of layer of intermetallic compounds depends on the level of soldering temperature and partially also on the dwell time at soldering temperature. Based on the records from EDW analyses, it may be

concluded that Ti does not contribute in bond formation, but it is locally bound in the dark phases contained in solder matrix (**Figure 25**).
