Effect of Ge doping on electrochemical migration of SAC alloys in 0.5 M NaCl solution

Author(s):  
Ali Gharaibeh ◽  
Balint Medgyes
2010 ◽  
Vol 146-147 ◽  
pp. 953-961 ◽  
Author(s):  
Li Hua ◽  
Gia Kuan Yang ◽  
Hong Quan Zhang

Due to lead-free pressure, Sn-Ag-Cu solder is regarded as the potential candidate. However, higher melting point and faintish soldering restrict its wide application. Metal or rare earth metal doping can improve its soldering. In this thesis, Ge doping in Sn-3.0Ag-0.5Cu (SAC) solder were discussed. Effect of metal Ge doping on electrochemical corrosion behavior of lead-free SAC solder in 3wt.% NaCl solution were investigated by potentiodynamic polarization measurement. The electrochemical migration(ECM)attributed to dendrites growth were employed by the salt immersion experiment, and the oxidation characteristic was researched by thermo gravimetric analysis(TGA). The surface morphology and elemental composition of various elements in the doped solder were determined by analyzing the corrosion product or dendrites formed on the specimen by SEM, EDAX techniques. The results showed that the dendrite growth can be accelerated after Ge doping comparing to Sn-3.0Ag-0.5Cu solder. The shapes of dendrites were completely different before and after Ge doping, the fore looked like as tree leaves, the latter looked like little stem, all dendrites grown from different kind of material can be well differentiated by the help of their fractal dimension. EDAX result showed that the content on dendrites of Sn-3.0Ag-0.5Cu solder doping with Ge were mainly Sn, only little Cl- and Na+. Corrosive experiment showed that the corrosive current density (Icorr) increased with Ge content increasing when the percent content of Ge was less than or equal to 1%, the contrary effect suitable to that Ge doping larger than 1%. TGA result showed that Ge doping could improve the anti-oxidation capacity of SAC solder comparing to no doped solder. It provided a good technical support to develop a new lead-free solder substituting for Sn-37Pb.


2013 ◽  
Vol 57 (2) ◽  
pp. 49 ◽  
Author(s):  
Bálint Medgyes ◽  
Balázs Illés ◽  
Gábor Harsányi

Author(s):  
W. Liebrich

HeLa cells were grown for 2-3 days in EAGLE'S minimum essential medium with 10% calf serum (S-MEM; Seromed, München) and then incubated for 24 hours in serum free medium (MEM). After detaching the cells with a solution of 0. 14 % EDTA and 0. 07 % trypsin (Difco, 1 : 250) they were suspended in various solutions (S-MEM = control, MEM, buffered salt solutions with or without Me++ions, 0. 9 % NaCl solution) and allowed to settle on glass tube slips (Leighton-tubes). After 5, 10, 15, 20, 25, 30, 1 45, 60 minutes 2, 3, 4, 5 hours cells were prepared for scanning electron microscopy as described by Paweletz and Schroeter. The preparations were examined in a Jeol SEM (JSM-U3) at 25 KV without tilting.The suspended spherical HeLa cells are able to adhere to the glass support in all solutions. The rate of attachment, however, is faster in solutions without serum than in the control. The latter is in agreement with the findings of other authors.


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