Suppressing Ni–Sn–P growth in SnAgCu/Ni–P solder joints

Influence of Palladium Thickness on the Soldering Reactions Between Sn-3Ag-0.5Cu and Au/Pd(P)/Ni(P) Surface Finish

“…5a) were the Sn-rich and Ni 3 P phase, respectively. In contrast, the average composition of the Ni-Sn-P layer (labeled ''c'') was 56.5 at.% Ni, 25.4 at.% Sn, and 18.1 at.% P, which is similar to the composition of the Ni 2 SnP phase reported in the literature [22][23][24][25][26] (Table I). The crystal structure of Ni 2 SnP was orthorhombic (lattice constant: a = 1.28260 nm, b = 0.35943 nm, c = 0.50896 nm; space group: Pnma) 27 and was further verified through TEM electron diffraction analysis.…”

“…The crystal structure of Ni 2 SnP was orthorhombic (lattice constant: a = 1.28260 nm, b = 0.35943 nm, c = 0.50896 nm; space group: Pnma) 27 and was further verified through TEM electron diffraction analysis. 23,24,28 Therefore, the results indicated that the small Ni-Sn-P grains on the Ni(P) surface (Fig. 3b) were likely Ni 2 SnP.…”

“…Between Ni 2 SnP and Ni 3 P, there were several possible intermediate phases, e.g., Ni 2 P and Ni 12 P 5 , which were also resolved in the Sn-3Ag-0.5Cu/Ni(P) case by Duh and colleagues. [22][23][24] However, Ni 2 P and Ni 12 P 5 were more stable under the condition that the P content in the Ni(P) metallization was high ($13 wt.%), [22][23][24] instead of the $7 wt.% P content utilized in this study. Therefore, Ni 2 P and Ni 12 P 5 may not be present in the reaction zone due to thermodynamic constraints.…”

Interface Reaction Between Electroless Ni–Sn–P Metallization and Lead-Free Sn–3.5Ag Solder with Suppressed Ni3P Formation

“…Because Ni 13 Sn 8 P 3 has a higher Sn content than the Ni-Sn-P deposit, it is speculated that transformation of the Ni-Sn-P deposit into the Ni 13 Sn 8 P 3 compound requires Sn supply from the solder, which is similar to the formation of Ni 2 SnP during the Ni-P/Sn-3.5Ag interfacial reaction. 6,[21][22][23][24] On the basis of these arguments, we believe that polycrystalline Ni 13 Sn 8 P 3 is formed by transformation of amorphous Ni-Sn-P metallization with outward diffusion of Ni and inward diffusion of Sn during the soldering reaction.…”

Detailed Phase Evolution of a Phosphorous-Rich Layer and Formation of the Ni-Sn-P Compound in Sn-Ag-Cu/Electroplated Ni-P Solder Joints

“…13 It was verified that the spalling phenomena was the result of Ni-Sn-P layer formation between the IMC and the Ni-P metallization. [12][13][14][15][16][17] However, limited data have been reported concerning the formation mechanism of the Ni-Sn-P layer. In this study, the formation of the Ni-Sn-P phase was systematically evaluated, and a description of the corresponding mechanism was proposed.…”