Lead-Tin-Arsenic Wiping Solder * 



By EARLE E. SCHUMACHER and G. S. PHIPPS 



SOME fourteen or more wiped joints occur in every mile of lead- 

 sheathed telephone cable, and in making these joints from one to 

 two million pounds of solder are used per year. To join cables a lead 

 sleeve of sufficient diameter to accommodate the bundle of spliced 

 wires is slid in place at the junction, the ends of the sleeve are beaten 

 to conform to the circumference of the cable, and an air-tight and 

 mechanically strong joint formed at each end of the sleeve by molding 

 a solidifying mass of solder into the desired shape. This last step is 

 called the wiping operation. 



The making of a successful wiped joint depends upon a satisfactory 

 composition in the solder and considerable skill on the part of the 

 splicer. The two factors are inter-related in that the more dextrous 

 operators can produce satisfactory joints with solder compositions 

 which could not be shaped by the average operator. The most 

 satisfactory composition for a wiping solder from practical tests has 

 been found to be about 38 per cent tin, 62 per cent lead. A solder 

 containing 40 per cent tin also possesses satisfactory handling qualities 

 and is used to some extent. If the tin content is much above 40 per 

 cent the workable temperature range in which the solder is plastic 

 becomes too limited for practical handling. The plastic range can be 

 increased by increasing the lead content above 62 per cent but then 

 it is found that the joint becomes coarse-grained and porous. The 

 highest practicable lead content is of course advantageous from an 

 economic standpoint. 



The impurities allowable in a wiping solder are also closely controlled 

 since in general small percentages of most impurities have been found 

 to have a harmful effect upon the handling character of the solder or 

 the properties of the joints. One exception, which has hitherto not 

 been recognized, is arsenic whose beneficial effects in small quantities 

 are discussed in this paper. 



An engineer would prefer to interpret the handling of a wiping solder 



in terms of basic properties which can be measured in the laboratory. 



Such attempts ^ have been made but with only limited success since 



* Metals and Alloys, Vol. 11, pp. 75-76, March 1940. 



^ "Some Physical Properties of Wiping Solders," D. A. McLean, R. L. Peek, Jr., 

 and E. E. Schumacher, Journal of Rheology, Vol. 3, January 1932, p. 53. 



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