Magnet electroplating

Patent metadata

Field	Value
Publication number	US-2017084372-A1
Application number	US-201615085931-A
Country	US
Kind code	A1
Filing date	Mar 30, 2016
Priority date	Sep 21, 2015
Publication date	Mar 23, 2017
Grant date	—

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

1 . A multilayered coating for a magnet, the multilayered coating comprising:
a first layer disposed on the magnet, wherein a portion of the first layer is diffused within intergranular cracks of the magnet; a second layer disposed on the first layer, the second layer characterized as having a first ductility; a third layer disposed on the second layer, the third layer characterized as having a second ductility less than the first ductility; and a fourth layer disposed on the third layer, the fourth layer having an exposed surface corresponding to an exterior surface of the multilayered coating, wherein the fourth layer is free of nickel and cobalt.

2 . The multilayered coating of claim 1 , wherein the fourth layer has a thickness greater than about 2 micrometers.

3 . The multilayered coating of claim 1 , wherein the first layer comprises nickel and has a thickness greater than about 2 micrometers.

4 . The multilayered coating of claim 1 , wherein the first layer comprises:
nickel; zinc; palladium; electrolessly deposited palladium; palladium and nickel; or palladium and cobalt.

5 . The multilayered coating of claim 1 , wherein the second layer comprises copper and has a thickness greater than about 2 micrometers.

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

7 . The multilayered coating of claim 1 , wherein the third layer comprises nickel and has a thickness of greater than about 1 micrometer.

8 . The multilayered coating of claim 1 , wherein the third layer comprises:
palladium; palladium and nickel; palladium and cobalt; or electrolessly deposited nickel.

9 . The multilayered coating of claim 1 , wherein the fourth layer has a thickness of greater than about 2 micrometers and comprises tin and copper.

10 . The multilayered coating of claim 1 , wherein the fourth layer comprises sub-layers, wherein the sub-layers comprise:
a gold layer; a palladium layer; a gold and palladium layer; a rhodium layer; a ruthenium layer; a rhodium and ruthenium layer; a silver layer; a poly(p-xylylene) polymer; or an epoxy 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 such that a portion of the first layer diffuses within intergranular cracks 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 fourth layer on the third layer such that the fourth layer has an exposed surface corresponding to an exterior surface of the multilayered coating, wherein the fourth layer is free of nickel and cobalt.

12 . The method of claim 11 , wherein the fourth layer comprises tin and copper, the method further comprising:
annealing the tin and copper plated magnet.

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

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

15 . A multilayered coating for a magnet, the multilayered coating comprising:
a first layer disposed on a surface of the magnet, the first layer including copper; a second layer disposed on the first layer, the second layer including tin and copper; and the third layer disposed on the second layer, the third layer corresponding to an outer layer of the multilayered coating, wherein the third layer includes at least one of gold, rhodium, ruthenium or palladium.

16 . The multilayered coating of claim 15 , wherein a thickness of the third layer is about 2 micrometers.

17 . The multilayered coating of claim 15 , wherein the first layer includes sub-layers of copper.

18 . The multilayered coating of claim 15 , wherein the third layer includes a rhodium and ruthenium alloy.

19 . The multilayered coating of claim 15 , wherein third layer is free of nickel and cobalt.

20 . The multilayered coating of claim 19 , wherein a first portion of the multilayered coating is covered with an adhesive and a second portion of the multilayered coating is covered with a polymer coating.

Assignees

• Apple Inc

Inventors

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

Classifications

• C23C18/42

  Coating with noble metals · CPC title

• H01F41/0253

  for manufacturing permanent magnets · CPC title

• H01F7/021 Primary

  Construction of PM (H01F7/0278 takes precedence; PM compositions H01F1/032) · CPC title

• C23C18/38

  Coating with copper · CPC title

• C23C18/1635

  Composition of the substrate · CPC title