Metal alloy sulfonic acid electroplating baths
AssigneesTechnic, Inc., Specialty Chemical Systems, Inc.
InventorsHyman D. Gillman, Brenda Fernandes, Kazimierz Wikiel
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Abstract
The use of alkali metal, alkaline earth metal, ammonium and substituted ammonium salts of alkyl and alkanol sulfonic acids as additives in pure metal and metal alloy sulfonic acid electroplating baths has a number of unexpected benefits including wider useful current density range, improved appearance and in the case of tin improved oxidative stability. An additional significant appearance is to reduce the overall costs of this type of bath with the more economical salts of alkyl and alkanol sulfonic acids. The metals and metal alloys include but are not limited to tin, lead, copper, nickel, zinc, tin/lead, tin/lead/copper, tin/zinc and zinc/nickel.
Claims16
A method of improving the plating performance of sulfonic acid based electroplating baths, comprising the step of replacing at least a portion of the alkyl sulfonic acid electrolyte with a salt of an alkanol sulfonic acid or of a mixture of an alkyl sulfonic acid and an alkanol sulfonic acid, wherein the replacement salt is selected from the group consisting of alkali metal, alkaline earth metal, and ammonium or substituted ammonium salts.
A method of increasing the useful upper current density range of a tin methane sulfonate plating bath and thereby allowing tin plating at higher speeds, said method comprising the step of adding an effective amount of sodium or potassium methane/methanol sulfonate to the bath.
A method of increasing the useful upper current density range of a tin/lead methane/methanol sulfonate plating bath and thereby allowing plating at higher speeds, said method comprising the step of replacing at least a portion of the methane sulfonic acid with sodium isethionate.
A method of inhibiting the oxidation of stannous ions in a tin plating bath containing methane sulfonic acid as the electrolyte, comprising the step of adding an effective amount of a salt of an alkanol sulfonic acid or of a mixture of an alkyl sulfonic acid and an alkanol sulfonic acid, wherein the adding salt is selected from the group consisting of alkali metal, alkaline earth metal, and ammonium or substituted ammonium salts.
An aqueous sulfonic acid electroplating bath comprising:
- (a) an alkyl or alkanol sulfonic acid electrolyte;
- (b) one or more soluble platable metal salts, wherein the platable metal is selected from the group consisting of tin, lead, copper, cadmium, indium, iron and mixtures thereof;
- and
- (c) a salt of a mixture of an alkyl sulfonic acid and alkanol sulfonic acid in an amount to improve the plating performance of the aqueous sulphonic acid electroplating baths, wherein the salt is selected from the group consisting of alkali metal, alkaline earth metal, and ammonium or substituted ammonium salts.
Dependencies are inferred from the claim text.