Autocatalytic plating bath composition for deposition of tin and tin alloys
View Patent ↗An autocatalytic tin plating bath containing Sn 2+ ions, Ti 3+ ions as reducing agent, an organic complexing agent and phenanthroline or a derivative thereof as stabilizing agent is disclosed. The plating bath is suitable for manufacture of printed circuit boards, IC substrates and metallization of semiconductor wafers.
1. An aqueous autocatalytic tin plating bath composition comprising a water-soluble source of Sn 2+ ions, a water-soluble source of Ti 3+ ions, at least one organic complexing agent and a stabilizing additive selected from the group consisting of compounds according to formula (1), formula (2) and mixtures thereof
wherein R1, R2, R3, R4, R5, R6, R7 and R8 according to formula (1) and R9, R10, R11 and R12 according to formula (2) are independently selected from the group consisting of hydrogen, halogen, nitro, methyl, ethyl, 1-propyl, 2-propyl, phenyl, hydroxyl, sulfonate, phenyl sulfonate, amino, amido, and carboxylate, and R13 is selected from the group consisting of hydrogen and sulfonate.
2. An aqueous autocatalytic tin plating bath composition according to claim 1 , wherein the pairs of residues R1 and R8; R2 and R7; R3 and R6; R4 and R5 of compounds according to formula (1) are independently selected from the same moiety of the group consisting of hydrogen, halogen, nitro, methyl, ethyl, 1-propyl, 2-propyl, phenyl, hydroxyl, sulfonate, phenyl sulfonate, amino, amido and carboxylate.
3. An aqueous autocatalytic tin plating bath composition according to claim 1 , wherein the concentration of the stabilizer additive according to formula (1), formula (2) and mixtures thereof ranges from 0.1 mg/l to 200 mg/l.
4. An aqueous autocatalytic tin plating bath composition according to claim 1 , wherein the concentration of Sn 2+ ions ranges from 2 g/l to 30 g/l.
5. An aqueous autocatalytic tin plating bath composition according to claim 1 , wherein the concentration of Ti 3+ ions in the autocatalytic plating bath ranges from 0.5 g/l to 20 g/l.
6. An aqueous autocatalytic tin plating bath composition according to claim 1 , wherein the at least one organic complexing agent is selected from the group consisting of aminocarboxylic acids, hydroxyl carboxylic acids and polycarboxylic acids.
7. An aqueous autocatalytic tin plating bath composition according to claim 1 , wherein the concentration of the at least one organic complexing agent ranges from 2 g/l to 60 g/l.
8. An aqueous autocatalytic tin plating bath composition according to claim 1 further comprising a source of inorganic pentavalent phosphorous ions.
9. An aqueous autocatalytic tin plating bath composition according to claim 8 , wherein the source of inorganic pentavalent phosphorous ions is selected from the group consisting of acids and salts of phosphate, hydrogenphosphate, dihydrogenphosphate and pyrophosphate.
10. An aqueous autocatalytic tin plating bath composition according to claim 8 , wherein the concentration of inorganic pentavalent phosphorous ions ranges from 20 g/l to 500 g/l.
11. An aqueous autocatalytic tin plating bath composition according to claim 1 , further comprising an inorganic sulfur-containing compound selected from the group consisting of sulfides, disulfides, polysulfides and thiosulfates.
12. A process for deposition of tin and tin alloys onto a substrate, the process comprising the steps of
(i) providing a substrate having metallic contact areas and
(ii) contacting the substrate with an aqueous autocatalytic plating bath composition according to claim 1 .
13. A process for deposition of tin and tin alloys onto a substrate, the process comprising the steps of
(i) providing a substrate having metallic contact areas,
(ii) contacting the substrate with a micro etch composition and thereafter
(iii) contacting the substrate with an aqueous autocatalytic plating bath composition according to claim 1 .