Method for making a base plate for suspension assembly in hard disk drive
View Patent ↗A swage mount that includes a flange, having a first side and a second side, and a cylindrically shaped hub. The hub is primarily comprised of a metal (such as stainless steel), and extends from the second side of the flange, and has an inner surface and an outer surface. The surface of the swage mount is plated with one or more layers of metal, or a combination of metals, which provide a) increased retention torque, and b) increased part cleanliness. This invention may be used in conjunction with surface hardened swage mounts that contain surface protrusions. In this case the metal plating prevents separation of the protrusions from the swage mount, thereby preventing contamination.
1. A method of manufacturing a swage mount for a base plate in a disk drive suspension assembly comprising the steps of:
forming a flange from a base metal;
forming a hub from the base metal, the hub extending from one side of the flange, the hub having protrusions of different heights on an outer surface, the protrusions being from a material different from the base metal; and
plating the outer surface of the hub with a metal to a thickness that entirely covers the lowest protrusion and partially covers the highest protrusion without entirely covering the highest protrusion.
2. The method of claim 1 further comprising terminating the plating step before the metal achieves a thickness of 50 microns.
3. The method of claim 1 further comprising terminating the plating step after the metal achieves a thickness of at least 0.5 microns and before the metal achieves a thickness of 50 microns.
4. The method of claim 1 wherein the plating step further comprises electrolyzing the hub in a sulfuric acid bath.
5. The method of claim 1 wherein the plating step further comprises a step for applying a strike plate to the hub.
6. The method of claim 1 wherein the plating step further comprises immersing the outer surface of the hub within a first metal plating bath being a Watts nickel bath.
7. The method of claim 6 wherein the metal is a first metal and the plating step further comprises immersing the hub in a second metal plating bath to plate the hub with a second metal.
8. The method of claim 5 wherein the applying step comprises placing the hub into a Woods bath having between 10 and 15 oz/gal nickel chloride, and applying an electrical current through the hub at a current density of about 1 ASF.
9. The method of claim 6 wherein the Watts nickel bath comprises 7 to 10 oz/gal nickel chloride.
10. The method of claim 6 wherein the Watts nickel bath comprises 30 to 40 oz/gal nickel sulfate.
11. The method of claim 6 wherein the Watts nickel bath comprises 4 to 6 oz/gal boric acid.
12. The method of claim 6 wherein the plating step further comprises immersing the hub within a second Watts bath containing saccharine.
13. The method of claim 7 wherein the second metal plating bath is a rhodium bath.
14. The method of claim 7 wherein the immersing step is continued until the second metal achieves a thickness of at least 3 microinches and is discontinued before the second metal achieves a thickness of 9 microinches.
15. The method of claim 8 wherein the Woods bath further comprises hydrochloric acid.
16. The method of claim 13 wherein the rhodium bath includes 1.3 to 2 g/L rhodium sulfate.
17. The method of claim 13 wherein the rhodium bath includes 25 to 80 ml/L sulfuric acid.
18. The method of claim 1 wherein the metal has a microstructure with a rough surface after being plated on the outer surface of the hub.
19. The method of claim 7 wherein the second metal is plated over the first metal and the plating of the second metal is harder and thinner than the plating of the first metal.
20. The method of claim 19 wherein the plating of the first metal and the plating of the second metal have a combined thickness that partially covers the highest protrusion without entirely covering the highest protrusion.