ABSTRACT
B. The Tin-Lead Alloys As mentioned earlier, tin-lead alloys are the most widely used of all solders. Most of the tin-lead solders commonly used are in the hypoeutectic range and therefore melt over a range of temperatures, and between these temperatures, part of the solder is molten and part is solid; thus the solder has a pasty consistency. The surface tension of molten solder increases with tin content, and has the advantage in terms of speed of work and quality of the joints. An increase in tin content, however, increases cost. Table 25 gives the melting characteristics of some tin-lead solders and lists their typical applications [410]. When referring to tin-lead solders, the tin content is customarily given first (e.g., 40/60 refers to 40 wt.% tin and 60 wt.% lead).
