METHOD OF ELECTROPLATING TIN FILMS WITH INDIUM USING AN ALKANESULFONIC ACID BASED ELECTROLYTE
A method comprising incorporating indium into an entire Sn film for preventing the growth of whiskers from the Sn film, wherein the Sn film is applied to a metallic substrate.
1 . An electrolyte composition comprising:
(a) a divalent tin salt;
(b) a trivalent indium salt; and
(c) an alkanesulfonic acid.
2 . The composition of claim 1 , further comprising a chelating agent.
3 . The composition of claim 2 , wherein the chelating agent is an organic carboxylic acid or a salt thereof.
4 . The composition of claim 2 , wherein the chelating agent is gluconic acid, malic acid, tartaric acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, a salt of gluconic acid, a salt of malic acid, a salt of tartaric acid, a salt of ethylenediaminetetraacetic acid, a salt of nitrilotriacetic acid, or a salt of diethylenetriaminepentaacetic acid.
5 . The composition of claim 1 , further comprising a hydrogen suppressor.
6 . The composition of claim 6 , wherein the hydrogen suppressor comprises an oligomer or a polymer of ethylene oxide, or an epihalohydrin copolymer.
7 . The composition of claim 1 , further comprising a pH adjustor to adjust the pH range of the composition to 0.1 to 5.
8 . The composition of claim 7 , wherein the pH adjustor is a caustic alkali agent.
9 . The composition of claim 1 , further comprising a chelating agent, a hydrogen suppressor, and a pH adjustor.
10 . The composition of claim 9 , wherein the chelating agent is an organic carboxylic acid or a salt thereof, the hydrogen suppressor is an oligomer or a polymer of ethylene oxide, or an epihalohydrin copolymer, and the pH adjustor is a caustic alkali agent.
11 . The composition of claim 1 , wherein the alkanesulfonic acid is methanesulfonic acid.
12 . The composition of claim 10 , wherein the alkanesulfonic acid is methanesulfonic acid.
13 . The composition of claim 1 , wherein the composition has a pH of 0.1 to 5.
14 . The composition of claim 9 , wherein the chelating agent is gluconic acid, malic acid, tartaric acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, a salt of gluconic acid, a salt of malic acid, a salt of tartaric acid, a salt of ethylenediaminetetraacetic acid, a salt of nitrilotriacetic acid, or a salt of diethylenetriaminepentaacetic acid.
15 . A method comprising:
providing an electrolyte bath comprising (a) a divalent tin salt, (b) a trivalent indium salt, and (c) an alkanesulfonic acid; and
co-electroplating tin and indium from the electrolyte bath onto a metallic substrate.
16 . The method of claim 15 , wherein 0.2 to 50 atomic percent indium is co-electroplated, based on the total amount of tin and indium.
17 . The method of claim 15 , wherein the electrolyte bath further comprises a chelating agent.
18 . The method of claim 15 , wherein the electrolyte bath further comprises a chelating agent, a hydrogen suppressor, and a pH adjustor.
19 . A method comprising:
co-electrodepositing indium, tin, and at least one additional metal other than indium and tin onto a metallic substrate thereby preventing growth of whiskers from the resulting film, wherein the film is an alloy containing greater than 90 wt % Sn.
20 . A method comprising:
co-electrodepositing tin, indium and at least one additional metal selected from Cu, Ag, Zn, Pb, Bi, Cd, or Au onto a metallic substrate thereby preventing growth of whiskers from the resulting film.
21 . A method comprising:
co-electrodepositing tin and indium onto a copper lead frame thereby preventing growth of whiskers from the resulting film.