Tin/tin-lead stripping solutions
AssigneeChemline Industries
InventorBento Da Fonte, Jr.
Life of this patent
Estimating the term…
Abstract
An improved tin/tin-lead stripping solution and method of preparing and using same, the solution including one or more compounds containing at least one amino (NH.sub.2) group, one carboxylic acid (--COOH) group and optionally a divalent sulfur group selected from the class of compounds known as amino acids or water/acid soluble derivatives thereof, or selected from the class of compounds known as aromatic carboxylic acids or water/acid soluble derivatives thereof, and incorporated in a basic fluoride-hydrogen peroxide tin-lead stripping solution.
Claims17
An improved tin/tin-lead stripping solution comprising:
- about 280 grams of ammonium bifluoride;
- about 100 milliliters of 35% by weight hydrogen peroxide;
- and
- about 1.0 gram of the amino acid glycine.
An improved tin/tin-lead stripping solution comprising:
- about 280 grams of ammonium bifluoride;
- about 100 milliliters of 35% by weight hydrogen peroxide;
- about 1.0 grams of the amino acid glycine;
- and
- about 0.4 gram of the aromatic carboxylic acid known as salicylic acid.
A method of stripping tin or tin-lead plating from a copper substrate comprising:
- preparing a solution containing about 280 grams ammonium bifluoride and about 100 milliliters of 35% by weight hydrogen peroxide;
- dissolving about 1.0 gram of glycerine in said solution to form a stripping solution;
- and
- immersing the plated substrate in said stripping solution for a pre-determined period of time.
A method of stripping tin or tin-lead plating from a copper substrate comprising:
- preparing a solution containing about 280 grams ammonium bifluoride and about 100 milliliters of 35% by weight hydrogen peroxide;
- dissolving about 0.4 gram of salicylic acid in said solution to form a stripping solution;
- and
- immersing the plated substrate in said stripping solution for a pre-determined period of time.
An acidic aqueous solution for selectively stripping tin or tin-lead solder alloy from a copper substrate comprising:
- a fluoride concentration of about 70-330 grams/liter in which the fluoride is supplied by hydrofluoric acid and/or one or more of its water/acid soluble salts, fluoboric acid and/or one or more of its water/acid soluble salts, or mixtures thereof;
- a hydrogen peroxide concentration of about 20-100 grams/liter actual hydrogen peroxide;
- and
- about 0.05-100 grams/liter of an amino acid compound, containing at least one amino group (NH.sub.2), one carboxylic acid group (--COOH), and/or about 0.01 gram up to the limit of solubility of an aromatic carboxylic acid having the general formula:
- ##STR2## where R.sub.1, R.sub.2, R.sub.3, =H, OH, NH.sub.2, COOH
- R.sub.4' =H, SO.sub.3 H
Dependencies are inferred from the claim text.