Magnet electroplating

Patent metadata

Field	Value
Publication number	US-9905345-B2
Application number	US-201615085931-A
Country	US
Kind code	B2
Filing date	Mar 30, 2016
Priority date	Sep 21, 2015
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

Coatings for magnetic materials, such as rare earth magnets, are described. The coatings are designed to reduce or prevent the release of one or both of nickel and cobalt from the coatings or from the underlying magnetic material. The coatings are designed to resist corrosion and release of nickel and cobalt when exposed to moist conditions. The coatings are also designed to be robust enough to withstand damage due to scratch forces. In some embodiments, the coatings include multiple layers of one or of metal and non-metal materials. The coated magnets are well suited for use in the manufacture of wearable consumer products.

First claim

The invention claimed is:

1. A multilayered coating for a magnet, the multilayered coating comprising:
a first layer disposed on the magnet;
a second layer disposed on the first layer and characterized as having a first ductility;
a third layer disposed on the second layer and characterized as having a second ductility less than the first ductility; and
a layer that is substantially free of nickel and cobalt disposed on the third layer and having an exposed surface corresponding to an exterior surface of the multilayered coating, wherein the layer that is substantially free of nickel and cobalt comprises a tin and copper alloy and has a thickness of about 7 micrometers or greater.

2. The multilayered coating of claim 1 , wherein the layer that is substantially free of nickel and cobalt has a thickness that is greater than a thickness of the second layer.

3. The multilayered coating of claim 1 , wherein the third layer is substantially free of nickel.

4. The multilayered coating of claim 1 , wherein the first layer comprises at least one of zinc, palladium, cobalt, nickel, or copper.

5. The multilayered coating of claim 1 , wherein the layer that is substantially free of nickel and cobalt comprises a polymer.

6. The multilayered coating of claim 5 , wherein the polymer includes poly(p-xylylene) or epoxy.

7. The multilayered coating of claim 1 , wherein the second layer comprises zinc.

8. The multilayered coating of claim 1 , wherein the third layer comprises at least one of zinc, palladium or cobalt.

9. The multilayered coating of claim 1 , wherein the first layer is electrolessly plated on the magnet.

10. The multilayered coating of claim 1 , wherein the first layer includes a nickel sub-layer and a palladium and nickel alloy sub-layer.

11. A method of forming a multilayered coating on a magnet, the method comprising:
plating a first layer on a surface of the magnet;
plating a second layer on the first layer, the second layer characterized as having a first ductility;
plating a third layer on the second layer, the third layer characterized as having a second ductility less than the first ductility; and
depositing a layer that is substantially free of nickel and cobalt on the third layer such that the layer that is substantially free of nickel and cobalt has an exposed surface corresponding to an exterior surface of the multilayered coating, wherein the layer that is substantially free of nickel and cobalt comprises a tin and copper alloy and has a thickness of about 7 micrometers or greater.

12. The method of claim 11 , further comprising:
annealing the multilayered coating on the magnet.

13. The method of claim 11 , wherein the first layer includes nickel, and wherein plating the first layer on the surface of the magnet comprises electrolessly plating the first layer on the surface of the magnet.

14. The method of claim 11 , wherein the third layer includes nickel, and wherein plating the third layer comprises electrolessly plating the third layer on the second layer.

15. A magnet having a multilayered coating, the multilayered coating comprising:
a first layer disposed on the magnet and comprising at least one of nickel, zinc, palladium, cobalt or copper;
a second layer disposed on the first layer and comprising at least one of copper or zinc;
a third layer disposed on the second layer and comprising at least one of zinc, palladium or cobalt; and
a layer that is substantially free of nickel disposed on the third layer and comprising at least one of a tin and copper alloy, aluminum, manganese, palladium, rhodium, ruthenium, gold, zinc, or a polymer, wherein the layer that is substantially free of nickel has a thickness that is about 7 micrometers or greater.

16. The magnet of claim 15 , wherein the layer that is substantially free of nickel has a thickness that is greater than a thickness of the second layer.

17. The magnet of claim 15 , wherein the first layer includes a nickel sub-layer and a palladium and nickel alloy sub-layer.

18. The magnet of claim 15 , wherein the layer that is substantially free of nickel is substantially free of cobalt.

19. The magnet of claim 15 , wherein the layer that is substantially free of nickel comprises a polymer, wherein the polymer includes poly(p-xylylene) or epoxy.

20. The magnet of claim 15 , wherein the layer that is substantially free of nickel comprises at least one of an aluminum and manganese alloy or a gold and palladium alloy.

Assignees

• Apple Inc

Inventors

• Sassaman Katie L
• Kwok Wai Man Raymund
• Qian Amy
• Blakemore Andrea L

Classifications

• Y10T428/24942

  including components having same physical characteristic in differing degree · CPC title

• C23C18/31

  Coating with metals · CPC title

• C23C18/42

  Coating with noble metals · CPC title

• Y10T428/12861

  Group VIII or IB metal-base component · CPC title

• H01F41/0253

  for manufacturing permanent magnets · CPC title