An Investigation of Intermetallics Formation Between Pd/Ag Metallization and Sn/Pb/Ag Solder

Intermetallics formation between metallization conductor Pd-Ag and solder 62Sn-36Pb-2Ag have been investigated by transmission electron microscopy (TEM) and X-Ray diffraction. Energy-dispersive X-Ray (EDX) analysis and Selected Area Electron Diffraction (SAED) analysis reveals the formation of the intermetallic compounds Ag5Sn, Ag3Sn, Pd2Sn, PdSn2, PdSn4, and PbPd3. X-Ray diffraction results confirm the coexistence of the above metallurgical phases and additional intermetallic compounds including Pd3Sn2, PdSn, and Pb3Pd5. Evident single phase intermetallic compound (IMC) layer structure is not observed. The different intermetallic phases coexist near the metallization/solder interface. Silver-tin intermetallic compounds are also observed in the solder.