exerted over a long period of time the procedure of example 7 is repeated but using a melt having a composition of sn 0 7cu 0 006ni or sn 0 7cu 0 02ni as a starting material to obtain a solder alloy according to the present invention having a composition of sn 0 7cu 0 006ni 0 003p or sn 0 7cu 0 02ni 0 003p in this example the effects of a treatment method according to the present invention were investigated using solder alloys prepared by the procedures of examples 1 and 2 solder pastes each comprising one of the alloys having the compositions shown in table 1 were applied by printing to a thickness of 0 15 mm to copper lands measuring 0 5 mm u00d7 0 5 mm of a printed circuit board copper pieces measuring 5 mm u00d7 5 mm u00d7 0 3 mm were then mounted on the paste on each land alloys 2 and 4 were alloys prepared by the procedures described by example 1 and example 2 respectively including p removal treatment alloys 1 and 3 were comparative alloys which had the same composition as alloys 2 and alloy 4 respectively but which had not undergone the p removal treatment employed in examples 1 and.