**2.2 SnAg3.5Ti4(Ce,Ga) solder**

The SnAg3.5Ti4(Ce,Ga) solder shown in **Figures 10** and **11** consists of a tin matrix with non-uniformly distributed constituents of intermetallic phases of binary Ti-Sn, Ag-Sn and Ag-Ti systems. The dark-grey phases contain an average of 31.5% Ti and 68.5% Sn, while the constituents of the Ti6Sn5 phase are concerned. The dark, clearly limited zones are formed by almost pure Ti. The composition of SnAg3.5Ti4(Ce,Ga) solder in the selected spots is shown in **Table 3**.

## **Figure 8.**

*Microstructure of the binary Ti-Sn system (SEM).*


**Table 2.** *Solder composition.*

**Figure 9.** *X-ray record of SnTi2 solder.*

**Figure 10.** *Microstructure of SnAg3.5Ti4(Ce,Ga) solder (SEM) + concentration profiles of elements.*

**Figure 12** shows the record of the diffraction analysis of SnAg3.5Ti4(Ce,Ga) solder. The following phases were revealed: Ti6Sn5, Ag3Sn, Ag3Ti and Ti2Sn. The solder consists of a tin matrix with non-uniformly distributed constituents of intermetallic Ti-Sn phases and the constituents of Ag3Sn and Ag3Ti (93% Sn, 6.5% Ag, 0.5% Ti) phase. The dark-grey phases shown in **Figure 11** in average contain 31.5% Ti and 68.5% Sn, while the Ti6Sn5 phase is concerned. The dark zones are composed of 100% Ti.

#### **2.3 Bi-In25Sn18 solder**

**Figure 13** shows the microstructure of bismuth-based BiIn25Sn18 solder of eutectic composition. The solder was manufactured in the form of cast ingot. It exerts a fine multi-crystalline structure. All phases are uniformly distributed in the solder, without any traces of formation of conglomerates and/or clusters causing the heterogeneity in the chemical composition of solder elements. Composition

**35**

**Figure 12.**

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

of the selected zones in BiIn25Sn18 solder is shown in **Table 4**. The ternary Bi-In-Sn system exerts two eutectics with a very low melting point. The composition of BiIn25Sn18 solder is very close to a ternary eutectics of Bi-In-Sn system, with a melting point of 77.5°C. Diffraction analysis performed on a specimen of BiIn25Sn18 solder (**Figure 14**) has revealed the presence of the following phases: Bi, Sn, In, BiIn2, In3Sn, InSn4, BiIn and Bi3In5. The solder exerts very fine and uniformly distributed multiphase structure. The grey matrix contains in average 80% Bi, 12.5% In and 7.5% Sn. The white phase is composed of Bi-In (32.5% In and 67.5% Bi) constituents, while the Bi-In phase is concerned. The dark-grey constituents in

**Ti [wt. %] Ag [wt. %] Sn [wt. %]**

A1 99.15 0 0.85 A2 31.08 0.73 68.19 A3 0.5 6.56 93.14

**Figure 13** show an increased tin content (13.5% Bi, 6.5% In, 80% Sn).

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

**Figure 11.**

**Table 3.**

*The SnAg3.5Ti4(Ce,Ga) solder (SEM).*

*SnAg3.5Ti4(Ce,Ga) solder composition.*

*X-ray record of SnAg3.5Ti4(Ce,Ga) solder.*

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

#### **Figure 11.**

*Lead Free Solders*

**Figure 9.**

*X-ray record of SnTi2 solder.*

**34**

**Figure 10.**

100% Ti.

**2.3 Bi-In25Sn18 solder**

*Microstructure of SnAg3.5Ti4(Ce,Ga) solder (SEM) + concentration profiles of elements.*

**Figure 12** shows the record of the diffraction analysis of SnAg3.5Ti4(Ce,Ga) solder. The following phases were revealed: Ti6Sn5, Ag3Sn, Ag3Ti and Ti2Sn. The solder consists of a tin matrix with non-uniformly distributed constituents of intermetallic Ti-Sn phases and the constituents of Ag3Sn and Ag3Ti (93% Sn, 6.5% Ag, 0.5% Ti) phase. The dark-grey phases shown in **Figure 11** in average contain 31.5% Ti and 68.5% Sn, while the Ti6Sn5 phase is concerned. The dark zones are composed of

**Figure 13** shows the microstructure of bismuth-based BiIn25Sn18 solder of eutectic composition. The solder was manufactured in the form of cast ingot. It exerts a fine multi-crystalline structure. All phases are uniformly distributed in the solder, without any traces of formation of conglomerates and/or clusters causing the heterogeneity in the chemical composition of solder elements. Composition

*The SnAg3.5Ti4(Ce,Ga) solder (SEM).*


#### **Table 3.**

*SnAg3.5Ti4(Ce,Ga) solder composition.*

#### **Figure 12.**

*X-ray record of SnAg3.5Ti4(Ce,Ga) solder.*

of the selected zones in BiIn25Sn18 solder is shown in **Table 4**. The ternary Bi-In-Sn system exerts two eutectics with a very low melting point. The composition of BiIn25Sn18 solder is very close to a ternary eutectics of Bi-In-Sn system, with a melting point of 77.5°C. Diffraction analysis performed on a specimen of BiIn25Sn18 solder (**Figure 14**) has revealed the presence of the following phases: Bi, Sn, In, BiIn2, In3Sn, InSn4, BiIn and Bi3In5. The solder exerts very fine and uniformly distributed multiphase structure. The grey matrix contains in average 80% Bi, 12.5% In and 7.5% Sn. The white phase is composed of Bi-In (32.5% In and 67.5% Bi) constituents, while the Bi-In phase is concerned. The dark-grey constituents in **Figure 13** show an increased tin content (13.5% Bi, 6.5% In, 80% Sn).

**Figure 13.** *The BiIn25Sn18 solder (SEM).*

