Influence of Noble Metal Coating on Wettability of Copper Substrate by Sn-Ag Eutectic Solder

Abstract

The influence of thin coatings (70 nm) of Au, Ag and Pd on the wettability of a Cu substrate by a Sn-3.5Ag eutectic solder was investigated using the contact angle measuring system combined with meniscograph tester. The wettability of the Cu substrate with Sn-3.5Ag was improved by the Au and Ag coatings, while reduced by a Pd coating, especially in terms of the contact angle. Namely, the contact angles were 29-30 on the Au coated-Cu substrate, 34-35 on the Ag coated-Cu substrate, 49-52 on the Pd coated-Cu substrate and 42-45 on the uncoated Cu substrate. On the wetted area, each coating layer dissolved into the solder and the Cu-Sn intermetallic compound was formed at the solder/ substrate interface as well as on the uncoated Cu substrate, but the coating metal layers remained on the unwetted area. The difference in wettability of the noble metal coating on the Cu substrate was found to be attributed to the difference in the substrate-flux interfacial tensions ( sf ).

Wetting and reaction of Sn-2.8Ag-0.5Cu-1.0Bi solder with Cu and Ni substrates

“…Hence, the development of solders without hazardous Pb, i.e., Pb-free solders, has been conducted on a worldwide basis. 2,3 Since Sn provides the metallurgical, environmental, economic, and supply criteria, the productions of Pb-free solders have been directed toward the Sn-based binary or ternary alloys, as reported by Wu et al 4 A number of eutectic or neareutectic Pb-free solders such as Sn-In, Sn-Bi, Sn-Ag, Sn-Ag-Cu, and Sn-Cu are being used as a replacement for Sn-Pb solders. The Sn-Ag system limits the solid solubility of Ag in Sn, which makes it more resistant to coarsening and forms more stable as well as uniform microstructure, whereas the addition of a small amount of Cu can prevent the dissolution of Cu from the base metal.…”

Joining of Copper Plates by Unusual Wetting with Liquid Tin and Tin–Lead Solder on “Surface Fine Crevice Structure”

“…Once the temperature reached 673 K, the sample was cooled at −10 K/min to room temperature. The contact angles of the solid Cu by liquid Sn are 37 at 510 K 12) , and 23 13) and 25 14) at 673 K, and those of solid Cu by liquid Sn-37 mass% Pb solder are 25 at 503 K 15) and 23 at 543 K 16) . Both combinations provide a wetting system, i.e.…”

Three-Dimensional Tissue Models Constructed by Cells with Nanometer- or Micrometer-Sized Films on the Surfaces

“…The coating covering nano-or micrometer-sized polymer thin films as liquids, gases, or solids on the surfaces of substrates, such as paper or fabric, for different applications in industrial fields due to functional materials may change the surface properties of the substrates, such as wettability, [1] adhesion, [2][3][4] and physical or chemical resistance. [5,6] In the case of a chemical coating, there are many methodologies, such as vapor deposition, [7][8][9] spraying, [10][11][12] roll-to-roll coating, [13,14] and chemical/electrochemical techniques, to modify and control the surface properties of the substrates for further applications.…”