This invention relates to methods and apparatus for washing, etching, rinsing, and plating substrates including electroless plating and electroplating.
In particular, magnetic disks are typically made of an aluminum alloy substrate having an electroless or electrodeposited nickel plate intermediate layer and a surface layer of magnetic read/write material sputtered onto the nickel plate. The nickel plating process involves submersing and agitating the aluminum alloy substrate in a plating bath to electroless plate a nickel-phosphorus alloy layer onto the substrate. Thereafter, the plated substrate may be polished and textured, and one or more underlayers, one or more magnetic layers, and one or more protective overcoats are deposited (e.g. by sputtering) onto the plated substrate.
There are various manufacturing processes utilized for plating substrates. For example, during some processes for making magnetic disks, the disks must be washed, rinsed, plated, and etched clean of foreign contamination of various types. Some of the fluids that are used are caustic and/or harmful to an operator which precludes manual handling during some or all steps of the washing, rinsing, plating or etching process.
For example, in one process, one first submerses, agitates, and soaks substrates in an alkaline cleaner (e.g. a KOH solution plus an inhibitor) in a first tank. Then one rinses the substrates by submersion, agitation, and soaking in a second tank. Next one submerses, agitates, and soaks the substrates in an acidic solution (e.g. phosphoric acid) in a third tank. Next one again rinses the substrates by submersion, agitation, and soaking in the second tank. Finally, the substrates are placed in a plating bath in a fourth tank. This plating bath comprises the chemicals used to plate a nickel-phosphorus alloy (NiP), e.g. nickel sulfates, sodium hypophosphite and chelating agents. The nickel plating chemistry can be a type 300 ADP, manufactured by Enthone Corp. Other plating chemistries are available from OMG Chemistries.
To implement the above processes, it is necessary to move the substrates between four separate tanks. To accomplish this, an entire plating rack and rotatable carousel may be transported between the four separate tanks. Such transportable, immersible, rotatable carousels for washing, etching, rinsing and plating substrates are known in the art.
An apparatus for immersing articles in a violently agitating electroplating bath has been described in detail in U.S. Pat. No. 4,516,523. The apparatus is capable of being immersed in a liquid bath and supports at least two dowels or rods on which are mounted apertured disks in a spaced apart relationship. Each dowel or rod has a gear fixed near one end and has a plurality of axially spaced circumferential grooves in each of which respective apertured disks are disposed. A pair of spaced wheels are provided to rotate in unison about a fixed central axle. Each wheel has a plurality of radially disposed slots into which respective dowels or rods are disposed so that each dowel continuously rotates about its own axis. The central axle supports a fixed sun gear disposed near one wheel and each rod has at one end a planet gear that meshes with the sun gear whenever the respective dowel or rod is nested within a respective pair of slots on the wheels. A motor and a corresponding gear assembly is provided to continuously rotate the pair of wheels and the at least two dowels about the central axle and continuously rotate the at least two dowels or rods about their own axis. However, U.S. Pat. No. 4,516,523 does not describe a continuous rotation of the disks about a central axis and a selective rotation of the disks about their own axis.
Although the apparatus shown and described in U.S. Pat. No. 4,516,523 is generally suitable for electroplating substrates, the apparatus is not shown to be versatile enough to provide optimal performance for each of the washing, etching, rinsing and plating process steps. In particular, the current inventors have found that the ability to provide a continuous rotation of the substrates about a central axis and a selective rotation of the substrates about their own axis allows optimization of the washing, etching, rinsing and plating process steps.
What is needed in the industry is a transportable, immersible, variably-rotatable apparatus that is movable between multiple process tanks and that is capable of providing a continuous rotation of the substrates about a central axis and a selective rotation of the substrates about their own axis which allows optimization of various washing, etching, rinsing and plating process steps.
An immersible disk support carousel 101 includes a pair of axially spaced carousel wheels referred to as a first mandrel support plate 114 and a second mandrel support plate 115 that are rigidly mounted on opposite ends of the central axle 109 by appropriate mechanical attachments known to those skilled in the art. The first mandrel support plate 114 may be rigidly mounted to rotatable sun gear 132. Rotation of the sun gear 132 by the motor 160 imparts rotation to the central axle 109 and the disk support carousel 101 including the first mandrel support plate 114 and the second mandrel support plate 115.
The disk support carousel 101, including the first mandrel support plate 114 and the second mandrel support plate 115, also includes a plurality of removable disk support mandrels 136 supported on and extending between the first mandrel support plate 114 and the second mandrel support plate 115. As shown in
Reception of the opposite ends of the mandrels 136 in the apertures 114a and recesses 115a permits the mandrels 136 to be removably supported on the spaced apart first mandrel support plate 114 and the second mandrel support plate 115 and to extend in a direction generally parallel to the central axle 109.
Each disk support mandrel 136 is capable of supporting up to 75 apertured disks 150 in a plurality of axially spaced circumferential grooves 138. Rotation of the sun gear 132 by the motor 160 imparts rotation to the central axle 109 and the disk support carousel 101 which in turn imparts planetary rotation to the plurality of disk support mandrels 136.
In addition to the planetary rotation of the mandrels 136 about the central axle 109 or central axis, the mandrels 136 (and thus the disks 150) are also capable of selective rotation about their own mandrel axis. Each disk support mandrel 136 has a mandrel gear 137 affixed to one end for engagement with a selectively rotatable ring gear 118. The ring gear 118 is in communication with a plurality of pulleys 122 to enable selective rotation of ring gear 118. The selectively rotatable ring gear 118 may be mechanically prevented from rotation by a striker pin 201 that is insertable into circular apertures 118a formed in ring gear 118, see
On the other hand, referring to see
Referring to
The striker assembly 200 is actuated when the immersible apparatus 100 is moved to a tank to implement a process that will benefit from having planetary rotation of the mandrels 136 about the central axle 109 or central axis, while not having the mandrels 136 (and thus the disks 150) rotating about their own mandrel axis. As shown in
As seen in
Although not forming part of the invention, the carousel 101 drive including the motor 160 and transmission gear 162 can be mounted in a fluid-tight immersible housing supported on the upper motor plate 102.
Each of the mandrels 136 is preferably made of a soft plastic such as Teflon and has a plurality of spaced parallel grooves 138 for respectively holding one of a plurality of wettable magnetic discs or other articles to be immersed in a metal electroless or electroplating bath, cleaning bath, rinse bath, etch bath, etc. As the motor 160 and transmission gear 162 rotate the idle gear 131, the idle gear 131 engages the external gear teeth on the sun gear 132 affixed to first mandrel support plate 114 for rotating the entire carousel 101 as a unit. Simultaneously, the planet or mandrel gears 137 on the ends of the disk support mandrels 136 also cause the mandrels 136 (and thus the disks 150) to rotate about their own mandrel axis due to engagement of the gear teeth on the planet or mandrel gears 137 with the external gear teeth on the selectively fixed ring gear 118 (striker pin 201 engaged). Thus, for processes that benefit from rotating mandrels 136 (and thus the disks 150) about their own axis, discs supported for immersion in an electroplating bath, cleaning bath, rinse bath, etch bath, etc are rotated with the mandrels 136 about their own central disk apertures and are further circulated through the agitating bath due to rotation of the carousel 101.
Alternatively, for processes that benefit from not rotating mandrels about their own mandrel axis, the striker pin 201 is disengaged, the ring gear 118 selectively rotates while the mandrel gears 137 and mandrels 136 (and thus the disks 150) do not rotate about their own mandrel axis due to engagement of the gear teeth on the mandrel gears 137 with the external gear teeth on the selectively rotating ring gear 118.
The mandrels 136 may easily be removed to mount and remove apertured discs therefrom by opening the gate 174 which permits one end of a mandrel 136 positioned in gap 172 to be radially removed from its mounting recess 115a in second mandrel support plate 115 following which the other end of the mandrel 136 is removed from its aperture 114a in the first mandrel support plate 114 by axial movement.
There are multiple manufacturing processes used in electroless or electroplating substrates. For example, during some processes for making magnetic disks, the disks must be washed, rinsed, zincate plated, rinsed, etched, rinsed, nickel-phosphorus plated, and rinsed. To implement the above processes, it is necessary to move the substrates between multiple separate tanks. To accomplish this, an entire plating rack and rotatable carousel may be transported between the multiple separate tanks.
Specifically, to electroless plate a nickel-phosphorus alloy layer (NiP) onto the substrate, a process may, for example, involve a dionized (DI) rinse in tank 1, a zincate plating in tank 2, a dionized (DI) rinse in tank 3, an acid etch in tank 4, a dionized (DI) rinse in tank 5, electroless nickel-phosphorus plating in tank 6, a dionized (DI) rinse in tank 7, etc.
The immersible apparatus 100 is versatile enough to provide optimal performance for each of the washing, etching, rinsing, and plating process steps. In particular, the immersible apparatus 100 can be moved from tank to tank to implement these processes and has the ability to provide a continuous rotation of the disks 150 about a central axle and a selective rotation of the disks 150 about their own mandrel axis to allow optimization of the washing, etching, rinsing and plating process steps.
For example, during conventional plating processes the mandrels (and thus the disks) are rotated about the central axle and the mandrel axis during all three operations (pretreatment, nickel plating and post treatment). In embodiments of the present invention, the mandrels (and thus the disks) rotate relative to the central axle and the mandrel axis before and after nickel plating but are non-rotating relative to the mandrel axis during nickel plating to reduce full surface waviness of the plated nickel. Embodiments of the present invention have demonstrated a reduction in full surface waviness (side-to-side delta) from 4 Angstroms to 1 Angstrom.
Act 104 includes providing the apparatus having the immersible rotatable carousel, the apparatus including a first mandrel support plate and a second mandrel support plate mounted for rotation in unison on a central axle, a rotatable ring gear mounted for selective rotation around the central axle, a plurality of disk support mandrels, the mandrels being supported by the first mandrel support plate and the second mandrel support plate to form the rotatable carousel, and a drive means for rotating the first mandrel support plate of the rotatable carousel, wherein rotating the first mandrel support plate causes the plurality of disk support mandrels (and thus the disks) to rotate around the central axle, the mandrels each having a mandrel axis that extends generally parallel to the central axle, the plurality of mandrels being capable of selective rotation around their own mandrel axis, wherein each of the mandrels having a mandrel gear affixed thereto and the mandrel gears having teeth in meshing engagement with external teeth on the ring gear such that the mandrels (and thus the disks) rotate around their own mandrel axis when the ring gear is prevented from rotating by a striker assembly having a striker pin and do not rotate around their own axis when the ring gear selectively rotates.
Act 106 includes providing at least one disk 150 mounted on one of the plurality of mandrels.
Act 108 includes mounting the apparatus having the rotatable carousel into the process tank having the solution such that the striker assembly causes the striker pin to couple to the ring gear to prevent the ring gear from rotating.
Act 110 includes actuating the drive means to rotate the first mandrel support plate of the rotatable carousel to cause the plurality of disk support mandrels (and thus the disks) to rotate around the central axle, the plurality of mandrels being capable of rotation around their own mandrel axis when the ring gear is prevented from rotating by the striker pin.
It should be appreciated by those with skill in this art that, although embodiments of the invention have been previously described with reference to a particular immersible apparatus, that the embodiments of the invention may be utilized with a wide variety of differing types of immersible apparatuses having different types of disks, wafers, substrates etc., and that the details describing the embodiments of the invention are not intended to limit the scope of the invention as set forth in the appended claims.
In the foregoing specification, embodiments of the invention have been described with reference to specific exemplary features thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and figures are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
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