Development of Sn–Zn lead-free solders bearing alloying elements

et al. 2017

Journal of Elec Materi

Cu and graphene-coated Cu substrates spread with Sn-Zn eutectic-based alloy containing 0.5 wt.%, 1 wt.%, or 1.5 wt.% Cu have been studied at 250°C. Soldering experiments were performed for wetting time of 3 min, 8 min, 15 min, 30 min, and 60 min in (1) presence of flux without argon protective atmosphere and (2) fluxless in argon atmosphere. Solidified solder-pad couples were cross-sectioned and examined using scanning electron microscopy with energy-dispersive spectroscopy to study their interfacial microstructure. To assess the effect of graphene coating on solder, Cu pads were covered by graphene using chemical vapor deposition. The results revealed that the liquid solder did not wet the graphene-coated copper in the absence of flux. Wetting took place only with use of flux, because it destroyed the graphene layer and enabled contact of the liquid solder with the copper. Experiments were designed to demonstrate the effect of Cu addition and graphene coating on the kinetics of the formation and growth of Cu 5 Zn 8 and CuZn 4 phases identified by x-ray diffraction analysis, Raman spectroscopy, and energy-dispersive spectroscopy. A decrease of about 60% in the thickness of the intermetallic layer was observed when applying the graphene interlayer in presence of flux. Addition of copper to the Sn-Zn alloy improved the wettability as the copper content was increased.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Graphene Layers on Phenomena Occurring at Interface of Sn-Zn-Cu Solder and Cu Substrate

Pstruś

Ozga

et al. 2017

Journal of Elec Materi

“…One of them constitutes the alloys of the Sn-Ag-Cu system (Ref 1), whereas the other constitutes the alloys based on Sn-Zn eutectic (Ref 2,3). The great advantage of Sn-Zn eutectic alloy is that its melting temperature (471 K) is close to the melting temperature of Sn-Pb eutectic solder (456 K).…”

Section: Introductionmentioning

confidence: 99%

Thermal Expansion, Electrical Resistivity, and Spreading Area of Sn-Zn-In Alloys

J. of Materi Eng and Perform

Fima

Pstruś

2013

Thermal expansion and electrical resistivity of alloys based on Sn-Zn eutectic with 0.5, 1.0, 1.5, and 4.0 wt.% additions of In were studied. Thermal expansion measurements were performed using thermomechanical analysis tester over 223-373 K temperature range. Electrical resistivity measurements were performed with four-probe method over 298-423 K temperature range. The electrical resistivity of alloys increases linearly with temperature and concentration of In; also coefficient of thermal expansion of the studied alloys increases with In concentration. Scanning electron microscopy revealed simple eutectic microstructure with In dissolved in Sn-rich matrix. The results obtained were compared with the available literature data. Spreading tests on Cu of Sn-8.8Zn alloys with 0.5, 1.0, and 1.5 at.% of In were performed. Wetting tests were performed at 250°C, by sessile drop method, by means of flux, and wetting times were 3, 8, 15, 30, and 60 min. In general, no clear effect of wetting time on spreading was observed.

“…[25][26][27][28][29] The formation of aluminum dendrites is based on the dissolution of aluminum grains, which are dissolved from their centers by the surrounding Sn solder. 24 On the other hand, the addition of Ag 23,30 and In 30,31 to SnZn alloys improves mechanical and wetting properties. The results in Ref.…”

Section: Introductionmentioning

confidence: 99%

Wetting of Sn-Zn-Ga and Sn-Zn-Na Alloys on Al and Ni Substrate

Bobrowski

Pawlak

et al. 2017

Journal of Elec Materi

Wetting of Al and Ni substrate by Sn-Zn eutectic-based alloys with 0.5 (wt.%) of Ga and 0.2 (wt.%) of Na was studied using the sessile drop method in the presence of ALU33 Ò flux. Spreading tests were performed for 60 s, 180 s, and 480 s of contact, at temperatures of 503 K, 523 K and 553 K (230°C, 250°C, and 280°C). After cleaning the flux residue from solidified samples, the spreading areas of Sn-Zn0.5Ga and Sn-Zn0.2Na on Al and Ni substrate were determined. Selected, solidified solder-pad couples were cross-sectioned and subjected to scanning electron microscopy with energy dispersive spectroscopy, x-ray diffraction study and synchrotron measurements of the interfacial microstructure and identification of the phases. The growth of the intermetallic Ni 5 Zn 21 phase layer was studied at the solder/Ni substrate interface, and the kinetics of the formation and growth of the intermetallic layer were determined. The formation of interlayers was not observed on the Al pads. On the contrary, dissolution of the Al substrate and migration of Alrich particles into the bulk of the solder were observed.