Chromium-free antitarnish adhesion promoting treatment composition
View Patent ↗The present invention is directed to an aqueous, antitarnish and adhesion promoting treatment composition, comprising: zinc ions; metal ions selected from the group consisting of tungsten ions, molybdenum ions, cobalt ions, nickel ions, zirconium ions, titanium ions, manganese ions, vanadium ions, iron ions, tin ions, indium ions, silver ions, and combinations thereof; and optionally, an electrolyte that does not contain potassium or sodium ions; wherein the treatment composition is substantially free of chromium, and wherein the treatment composition forms a coating on a substrate or material that enhances adhesion of a polymer to the material. The present invention is also directed to materials coated with the above treatment composition, and methods of coating materials using the above composition.
1. A material coated with an antitarnish and adhesion treatment coating, said antitarnish and adhesion treatment coating comprising
zinc or zinc oxide atoms; and
metal or metal oxide atoms selected from the group consisting of tungsten, molybdenum, cobalt, nickel, zirconium, titanium, manganese, vanadium, iron, tin, indium, silver, and combinations thereof;
wherein said coating is substantially free of chromium, and wherein said coating provides a tarnish resistance at least for 30 min at 250° C., and wherein said coating contains nodular structures that enhance adhesion of a polymer to said material.
2. The coated material of claim 1 , wherein said material comprises a material selected from the group consisting of copper, copper alloy, nickel, iron, aluminum, steel, stainless steel, zinc, tin, silver, palladium, gold, titanium, carbon, metallized non-conductors, and combinations thereof.
3. The coated material of claim 1 , wherein the thickness of said coating on said material ranges from about 15 to about 500 Angstroms.
4. The coated material of claim 1 , wherein said coating contains from about 25 to about 1000 of said nodular structures per 16 square microns.
5. The coated material of claim 1 , wherein said nodular structures each have an average length in the range of from about 0.01 micron to about 1 micron, and an aspect ratio (length to diameter) of from about 1:1 to about 8:1.
6. The coated material of claim 1 , wherein said enhanced adhesion comprises greater than 1000 psi following exposure of said coated substrate to 85% RH/80-85° C. for 168 hr, followed by a thermal shock in approximately 260° C. solder for 120 sec.
7. The coated material of claim 1 , comprising a coated substrate.
8. The substrate of claim 7 , comprising an electronic device.
9. The substrate of claim 7 , comprising a device/leadframe assembly.