LEAD-FREE AND ANTIMONY-FREE TIN SOLDER RELIABLE AT HIGH TEMPERATURES

1 . A lead-free, antimony-free solder alloy comprising:

(a) 3 to 5 wt % of silver

(b) 2.5 to 5 wt % of bismuth

(c) 0.3 to 2 wt % of copper

(d) at least one of the following elements

up to 1 wt. % of nickel

up to 1 wt. % of titanium

up to 1 wt. % of cobalt

up to 3.5 wt. % of indium

up to 1 wt. % of zinc

up to 1 wt. % of arsenic

(e) optionally one or more of the following elements

0 to 1 wt. % of manganese

0 to 1 wt. % of chromium

0 to 1 wt. % of germanium

0 to 1 wt. % of iron

0 to 1 wt. % of aluminum

0 to 1 wt. % of phosphorus

0 to 1 wt. % of gold

0 to 1 wt. % of gallium

0 to 1 wt. % of tellurium

0 to 1 wt. % of selenium

0 to 1 wt. % of calcium

0 to 1 wt. % of vanadium

0 to 1 wt. % of molybdenum

0 to 1 wt. % of platinum

0 to 1 wt. % of magnesium

0 to 1 wt. % of rare earths

(f) the balance tin, together with any unavoidable impurities;

wherein the alloy affirmatively contains said Ni in a concentration of 0.01 to 1 wt %; and

wherein the alloy affirmatively contains said Ge in a concentration of 0.005 to 1.

2 . The solder alloy according to claim 1 , wherein the alloy comprises:

from 3.5 to 4.5 wt. % of silver;

from 2.5 to 4 wt. % of bismuth;

from 0.3 to 0.8 wt. % of copper;

from 0.03 to 1 wt. % nickel;

from 0.005 to 1 wt. % germanium,

the balance tin, together with any unavoidable impurities.

3 . The solder alloy according to claim 2 , wherein the alloy comprises from 2.8 to 4 wt % bismuth.

4 . The solder alloy according to claim 2 , wherein the alloy comprises from 0.6 to 0.8 wt % copper.

5 . The solder alloy according to claim 2 , wherein the alloy comprises from 0.03 to 0.6 wt. % nickel.

6 . (canceled)

7 . (canceled)

8 . The solder alloy according to claim 2 , wherein the alloy comprises: from 2.8 to 4 wt. % bismuth; and from 0.1 to 0.3 wt. % nickel.

9 . The solder alloy as claimed in claim 2 , wherein the alloy has melting point of from 195 to 222° C.

10 . The solder alloy as claimed in claim 2 in the form of a bar, a stick, a solid or flux cored wire, a foil or strip, or a powder or paste (powder plus flux blend), or solder spheres for use in ball grid array joints or chip scale packages, or other pre-formed solder pieces, with or without a flux core or a flux coating.

11 . A soldered joint comprising an alloy as defined in claim 2 .

12 . A method of forming a solder joint comprising:

(i) providing two or more work pieces to be joined;

(ii) providing a solder alloy as defined in claim 2 ; and

(iii) heating the solder alloy in the vicinity of the work pieces to be joined.

13 . (canceled)