Solder electroplating bath including brighteners having reduced volatility
AssigneeLucent Technologies Inc.
InventorsJoseph A. Abys, Frank Stanley Humiec, Kenneth J. Murski, Yun Zhang
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Abstract
In accordance with the invention, the volatility of a solder plating bath with volatile brighteners such as aldehydes has its volatility reduced by the addition of diols to the bath. The diols are advantageously 1,3 propanediol or 1,2 propanediol and are accompanied by lower molecular weight alcohols. In a preferred embodiment, a diol along with low alcohol is added to a bath comprising sulfonic acid, surfactant, grain refiner and brightening agents comprising an aromatic aldehyde and a carboxylic acid.
Claims17
An electroplating solution useable for plating tin, lead or tin-lead alloy solder coatings comprising:
- a sulfonic acid electrolyte;
- at least one of a tin sulfonate salt or a lead sulfonate salt;
- a non-ionic surfactant comprising an aromatic compound;
- a grain refiner comprising a heterocyclic compound;
- at least one brightening agent that is volatile at room temperature, and
- at least one alkyl diol for reducing the volatility of the bath.
A process for electroplating a substrate with tin, lead or tin-lead alloys comprising the steps of:
- providing an electroplating solution comprising a sulfonic acid electrolyte;
- at least one of a tin sulfonate salt or a lead sulfonate salt;
- a non-ionic surfactant comprising an aromatic compound;
- a grain refiner comprising a heterocyclic compound;
- brightening agents consisting essentially of an aromatic aldehyde and a carboxylic acid;
- and an alkyl diol;
- positioning the substrate in the electroplating solution;
- applying current;
- and
- maintaining the temperature of the electroplating solution at a sufficiently high temperature so that the substrate is electroplated with a bright solder coating having a carbon content of less than about 0.1%.
Dependencies are inferred from the claim text.