Composition and Microstructure Control of Tin-Bismuth Alloys in the Pulse Plating Process

Abstract

Pulse plating of Sn-Bi alloys were investigated from a bath containing three compounds, including citric acid (CA), ethylenediaminetetraacetic acid (EDTA), and polyethylene glycol (PEG400) at pH = 1. Based on the linear sweep voltammetric (LSV) analysis, the large gap in the onset deposition potential between Sn and Bi metals led to displacement deposition at the interface between metallic Sn atoms and Bi3+ ions in the time-off (toff) period. Consequently, the pulse-plating parameters (i.e., duty percentage in the pulse cycle and pulse frequency) were adjusted to affect the double-layer charging effect and the mass transport process to control the composition and morphology of alloys. This pulse plating method provides a reliable route to obtain uniform Sn-Bi alloys of high Sn contents (e.g., 80Sn-20Bi and 90Sn-10Bi) and the eutectic 42Sn-58Bi deposit. Various Sn-Bi deposits were characterized by the scanning electron microscopic (SEM), energy-dispersive spectroscopic (EDS), and X-ray diffraction (XRD) analyses.

Cathodic Deposition of TiO2: Effects of H2O2and Deposition Modes

“…9a-9c (or 9d-9f), the particle size of TiO 2 aggregates decreases with increasing the DP value. Since PR deposition with high DP values will approach a PS deposition mode, 45,46 the SEM images in Fig. 9a and 9d are very similar to that shown in Fig.…”

Electrodeposition of lead‐free solder alloys

“…Co‐deposition of Sn‐Pb solders has been quite successful (Field and Weill, 1951; Kohl, 1982; Kim et al , 1996; Lin and Liu, 1999) which can be attributed to the small difference in standard reduction potential between the two elements (Sn 2+ /Sn: −0.137 V and Pb 2+ /Pb: −0.125 V). With rising emphasis to restrict the usage of toxic Pb in electronic applications, electroplating of alternative binary systems such as Sn‐Ag (Ezawa et al , 2001; Kim et al , 2004; Neveu et al , 2006; Chen et al , 2008; Qin et al , 2008; Hrussanova and Krastev, 2009; Venkatasamy et al , 2011), Sn‐Bi (Fukuda et al , 2001; Suh et al , 2006; Tsai et al , 2007; Tsai and Hu, 2009a, b, 2011a; Lee et al , 2011), Sn‐Cu (Han, 2009; Survila et al , 2009, 2010), Sn‐Zn (Wang et al , 2001; Guaus and Torrent‐Burgues, 2005; Dubent et al , 2010; Arici et al , 2011), as well as ternary systems such as Sn‐Ag‐Cu (Joseph and Phatak, 2008, 2010; Zhang et al , 2008, 2009; Han, 2009; Han et al , 2009; Qin et al , 2010; Tsai and Hu, 2011b) are being pursued.…”

Electrodeposition of Tin-Bismuth Alloys: Additives, Morphologies and Compositions

“…Tin-bismuth alloys have been electrodeposited from different baths using direct-current and pulsed-current techniques [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. The standard reduction potential of Bi 3+ is 444 mV nobler than that of Sn 2+ .…”

“…Based on a fractional factorial design study, Tsai and Hu found that pH, plating current density and citric acid concentration are the key factors influencing the composition of Sn-Bi deposits [19,20]. Highest Sn content (64%) has been obtained at pH of 6.5, 20 mA/cm 2 current density and 0.3 M citric acid concentration.…”