Electroless coated disks for high temperature applications and methods of making the same
View Patent ↗A disk for a hard disk drive is provided. The disk comprises a substrate comprising aluminum, and a coating layer disposed over the substrate. The coating layer comprises an alloy of Ni, X 1 and X 2 , wherein X 1 comprises one or more elements selected from the group consisting of Ag, Au, B, Cr, Cu, Ga, In, Mn, Mo, Nb, Pb, Sb, Se, Sn, Te, W, Zn and Zr, and wherein X 2 comprises either B or P, and wherein X 1 and X 2 do not comprise the same elements.
1. A method of forming a disk for a hard disk drive, the method comprising:
providing a substrate comprising aluminum;
disposing a zincate layer over the substrate; and
electroless plating a coating layer over the zincate layer, the coating layer comprising an alloy of Ni, X 1 and X 2 ,
wherein X 1 comprises Cu and an element selected from the group consisting of B, In, Mo, and W,
wherein X 2 comprises either B or P,
wherein X 1 and X 2 do not comprise the same elements, and
wherein the alloy comprises between about 1.5 and about 42 weight percent of each constituent of X 1 and between about 3 and about 11 weight percent X 2 .
2. The method according to claim 1 , wherein the electroless plating the coating layer comprises:
disposing the substrate in a plating bath comprising:
one or more metal sources for each of Ni and X 1 ,
a reducing agent for reducing the one or more metal sources, the reducing agent comprising X 2 ,
one or more complexors to reduce metal precipitation,
one or more stabilizers, and
one or more pH adjusting additives.
3. The method according to claim 2 , wherein the plating bath has a pH of between about 5 and about 9.
4. The method according to claim 2 , wherein the plating bath is maintained at a temperature between about 160° F. and about 195° F. while the substrate is disposed in the plating bath.
5. The method according to claim 2 , wherein the plating bath has a metal turn over (MTO) of less than 6.
6. The method according to claim 5 , wherein the MTO of the plating bath is maintained between about 2.0 and 4.5.
7. The method according to claim 2 , wherein the one or more metal sources for Ni comprise one or more of nickel sulfate, nickel sulfamate, nickel acetate, nickel chloride, nickel hypophosphite, and nickel fluor-borate.
8. The method according to claim 2 , wherein the one or more metal sources for X 1 comprise one or more of copper sulfate, copper iodate, copper iodide, and copper chloride.
9. The method according to claim 2 , wherein the reducing agent comprises one or more of salts of hypophosphite, nickel hypophosphite, dimethylamine borane (DMAB), diethylamine borane (DEAB), amine borane, and sodium borohydride.
10. The method according to claim 2 , wherein the one or more complexors comprise one or more of citric acid, malic acid, lactic acid, amino acids, tartaric acid, ethylenediaminetetraacetic acid (EDTA), a carboxylic acid, and any salts there.
11. The method according to claim 2 , wherein the one or more stabilizers comprise one or more cations of Bi, Cd, Cu, Hg, In, Mo, Pb, Sb and Sn, AsO −2 , MoO −4 , IO 3 − , NO 3 − , maleic acid, itaconic acid, methylbutynol, N,N Diethyl 2 propyne 1 amine and 2 Butyne 1,4 diol.
12. The method according to claim 2 , wherein the one or more stabilizers comprise iodine or a compound thereof.
13. The method according to claim 2 , wherein the one or more pH adjusting additives comprise one or more of K 2 CO 3 , Na 2 CO 3 , KHCO 3 , NaHCO 3 , NaOH, KOH, NH 4 OH and N(CH 2 CH 3 ) 3 .
14. The method according to claim 2 , wherein the one or more pH adjusting additives comprise a buffer selected from the group consisting of boric acid, borax, triethanolamine, triethylene pentamine, diethylenetriamine, acetate salts, propionate salts, succinate salts, and adipate salts.
15. The method according to claim 2 , wherein the plating bath further comprises one or more dispersants, anionic surfactants, nonionic surfactants, and organosulfur compounds.