軟ろう接に関する研究(第 1 報)

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There are three fundamental points to understand the wettability of molten soders. Namely, (a) The magnitudes of surface energy in mother metal or molten solder and interfacial energy of mother metal/molten solder are closely related to the propriety of wettability. (b) The alloying tendency between mother metal and molten solder or the magnitude of diffusion power of molten solder to mother metal is related to propriety of wettability. (c) The magnitudes of alloying energy or potential energy due to gravity are related to propriety of wettability. Generally, wettability varies with chemical composition of soft solders, fluxes, mother metals and surface condition, heating temperature or atmosphere. And necessary condition to get perfectly wet is the following equation. σ_S>σ_<LS>+σ_L・cosθ where σ_S; surface tension of mother metal. σ_<LS>; interfacial tension of solder/mother metal. σ_L; surface tension of solder. θ; equilibrium contact angle of solder/mother metal. Accordingly, in this test, authors have measured the spread area of solders combined with various fluxes and investigated the surface tension of mother metal, interfacial tension of solder/mother metal, surface tension of solders and viscosity of fluxes which have effect on the magnitude of spread area. As fluxes, ZnCl_2,ZnCl_2-SnCl_2・2H_2O, ZnCl_2-NH_4Cl, ZnCn_2-NaCl, ZnCl_2-KCI binary system fluxes and ZnCl_2-SnCl_2・2H_2O-NH_4Cl ternary system flux are used. As solders, Sn-Pb, Pb-Cd, Sn-Bi, Sn-Cd, Sn-Zn and teernary solders are used. The results obtained from above investigations are as follows. (1) The spread area of eutectic solder at 350℃ is little affected by flux such as ZnCl_2-NaCl or ZnCl_2-KCl. (2) The spread areas of Sn-Pb, Zn-Cd and Pb-Cd solders are comparatively satisfactory with ZnCl_2 flux at 350℃. And in the case of Sn-Pb, Sn-Bi, Sn-Cd, Pb-Sn and Pb-Cd, i.e., two component solders, the spread area with ZnCl_2 : NH_4Cl=2 : 1 binary flux at 350℃ has a comparatively larger value than with ZnCl_2 only. (3) With regard to the effects on spread area of the 3rd alloying metals in eutectic solders, the effects of these metals are not a negligible factor; especially, the spread area is increased by addition of As to eutectic solders. As the quality is deteriorated by addition of As, Bi and Zn, addition of these metals is to be avoided. (4) When Sn70Wt%-Zn30Wt%, Sn70Wt%-Bi30Wt%, Sn70Wt%-Pb30Wt% and Sn70Wt%-Cd30W% i.e., two component solders combined with ZnCl_2; SnCl_2・2H_2O=2 : 1 and ZnCl_2 : SnCl_2・2H_2O : NH_4Cl=2 : 1 : 1 system fluxes are used, the temperature dependency of the spread area of solders is relatively high in range from 300 to 400℃. The spread area of above solders combined with ZnCl_2 : SnCl_2・2H_2O : NH_4Cl=2 : 1 : 1 ternary flux has a larger value than ZnCl_2 : SnCl_2・2H_2O=2 : 1 binary flux.
社団法人溶接学会の論文
1969-06-25

軟ろう接に関する研究(第 1 報)

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