Effect of Bismuth and Silver on the Corrosion Behavior of Lead-free Solders in 3.5 wt% NaCl Solution

Abstract

IntroductionOne of the key reliability issues of the electronics technology is carry about the solder joints testing. Usually, the different failures can lead back to the not adequate physical properties (e.g. wetting behaviour, mechanical strength, etc.) of the solder alloy and/or the not adequate applied technological processes (e.g. reflow temperature profile), which have to be improved. This challenge was updated in 2006, with the introduction of lead-free solder alloys governed by the RoHS directive of EU [1]. Due to the lead-free limitations, different solder types such as near-eutectic Tin-Silver, Tin-Copper, and Tin-Zinc alloys were produced as replacement for Tin-Lead solder materials. Furthermore, solders with more alloying elements, such as (Tin-Silver-Copper, Tin-Zinc-Silver, Tin-Zinc-Indium) and/or (Tin-Zinc-Silver-Aluminum, Tin-Silver-Bismuth-Copper, TinIndium-Silver-Antimony) were also investigated as replacements for Pb-free types [2]. While, the different qualifying studies of the Pb-free solder alloys are even active topics [3] and one of the issues is carry about humidity induced failures, like electrochemical corrosion [4,5]. Different results were also published related to novel Pb-free solder alloys in terms of reliability topics, such as solderability [6], intermetallic layer (IML) investigation [7], shear force tests [8], wetting investigations [9] or (solid state physics) migration tests [10]. On the other hand, the investigations of humidity induced failures (like corrosion) of Pb-free solder alloys are not deeply addressed in the scientific publications. In our former publication [11], various microalloyed Pb-free solders tested in terms of corrosion resistance using electroanalytical tests. In that study [11] different Pb-free solder alloys (four micro-alloyed and a Sn96.5Ag3Cu0.5 alloy as reference) were compared using potentiodynamic polarisation tests. During polarisation tests, the sample (working electrode) is scanned from a cathodic polarisation state, and after reaching the corrosion potential (Ecorr) it begins anodic polarisation. When the sample reaches the passivation potential, if possible a passivation film begins to form on the surface and the current density at this point is called the critical current density (Icrit). After this point the corrosion current density begins to drop to a much lower value. When a compact passivation film

Microstructural Effect on the Corrosion Behavior of N- and P-Type Bismuth Tellurides Fabricated by Induction Melting

“…The plots showed that the samples had a capacitive response in a medium frequency range and a resistive response at higher frequencies. The phase angle shift of − 55 • shows the semi-capacitive response due to the heterogeneity of the electrode surface [14]. The obtained results agree with the reported data by Rosalbino et al [3].…”

Whisker Development from SAC0307-Mn07 Solder Alloy

“…[6]. Other researches tried to improve the mechanical properties of the SAC alloy with further alloying of Bi and Mn in a higher amount between 0.1-1 wt% [7,8]. Lin et al [9] reached significant mechanical improvement during drop tests in the case of low Ag content Sn-l.0Ag-0.5Cu alloys doped with Mn and Ti (0.15 and 0.5wt%).…”

Galvanic corrosion analysis of a Bi–Zn solder alloy coupled to Ni and Cu substrates

“…While mechanical and physical properties of these new alloys are always evaluated, the same cannot be said for their corrosion behaviour. Although numerous attempts have been conducted to investigate the corrosion behaviour of lead-free solder alloys [29][30][31][32][33][34][35][36][37][38], there is still little information regarding the galvanic corrosion of solder alloys in contact to Cu or Ni substrates; in fact, only a few studies have been reported to date [39,40].…”