US20060163078A1

US20060163078A1 - Single pass, dual thickness electroplating system for head suspension components

Info

Publication number: US20060163078A1
Application number: US11/339,427
Authority: US
Inventors: Todd Peter
Original assignee: Hutchinson Technology Inc
Current assignee: Hutchinson Technology Inc
Priority date: 2005-01-25
Filing date: 2006-01-25
Publication date: 2006-07-27
Also published as: JP2008528807A; WO2006081321A3; WO2006081321A2

Abstract

A method for simultaneously electroplating exposed conductor regions on both sides of a disk drive suspension component by providing an electroplating system having a bath of electroplating solution with first and second anodes in the bath. The suspension component is positioned in the bath of electroplating solution between the first and second anodes. A first electroplating current is produced between the first anode and the exposed conductor regions on the first surface of the component. A second electroplating current is produced between the second anode and the exposed conductor regions on the second surface. Layers of conductive material are thereby plated onto the exposed conductor regions on both sides of the component. By controlling parameters of the first and second plating currents, such as time and magnitude, the layers of conductive material can be plated to the same or different thicknesses on the opposite sides of the conductors.

Description

REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser. No. 60/646,934 filed on Jan. 25, 2005 and entitled “Single Pass Dual Thickness Electroplating Method for Head Suspension Components,” which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The invention is a system for electroplating portions of disk drive head suspension components. In particular, the invention is a system for simultaneously electroplating different portions of the suspension components to different plating thicknesses.
BACKGROUND OF THE INVENTION
Copper or copper alloy leads or conductors, terminal pads and other portions of so-called wireless or integrated lead disk drive head suspension components such as flexures are commonly electroplated with gold, nickel, silver, and/or other conductive materials to enhance electrical connectivity and reduce contamination. For example, one common plating configuration includes a layer of nickel under a layer of gold.
FIG. 1 is a schematic illustration of the components of a prior art plating system 10 located in a plating tank (not shown) of an electroplating system that can be used to plate conductive materials to portions of the suspension components. Equipment of the type shown in FIG. 1 is commercially available from suppliers such as PENC Chemicals and Machinery Co. of Hong Kong. As shown, a plurality of anodes 118 are spaced around a circular rack 116. Panels 114 having suspension components with portions to be electroplated are mounted to the rack 116. The panel 114 functions as a cathode. More particularly, the layer of conductive leads that are exposed to the plating solution in the plating tank and thereby intended to receive the conductive material function as the cathode.
Wireless flexures manufactured from laminated sheets of material using subtractive processes typically have most (e.g., about 95%) of the surface area to be electroplated on a first side 120 of the panel, and the remainder of the surface area to be electroplated on a second side 122. Wireless flexures typically have a spring metal layer with conductors, terminal pads, and the like formed on one side of the spring metal layer. The flexures are therefore typically mounted on the panel 114 so that the conductors formed onto the spring metal are on the first side 120 of the panel 114. Portions of the spring metal layer attached to the conductors may be removed to create an access to the conductors from the second side 122 of the flexure. Some of these portions of the flexure with access to the conductors from both sides may be known as flying lead regions and the portions of the conductors in this region are known as flying leads.
Electroplating tends to be a very directional process. Current flowing between the anodes 118 and the exposed conductive material (which acts as a cathode) tends to cause the plating material in the plating solution to plate onto the exposed conductive material on the first side 120 of the panel 114 (i.e., the side that is positioned to directly face the anodes 118). However, there is a relatively small amount of current leakage from the anode to the second side 122 of the panel 114. Since the amount of surface area to be plated on the second side 122 of the panel 114 is also relatively small, this leakage current is typically sufficient to produce suitable electroplating on the second side 122, even though the conductive material on the second side of the panel 114 is not exposed to the anodes 118, (i.e., the second side does not directly face the anodes).
It is sometimes desirable to electroplate different portions of a suspension component with different thicknesses of plating material. For example, it is generally desirable to provide a relatively thin electroplated layer at terminals that will be solder ball bonded (SBB) to terminals of a read/write head mounted to the suspension. A thin plated layer is desirable at this location to reduce solder embrittlement that can sometimes occur if too much gold plating mixes with the solder. On the other hand, relatively thick plated layers are desirable on the back side of flying leads where they are ultrasonically bonded to other disk drive components. The relatively thick gold plating provides an enhanced bond in this application.
Known approaches for plating different flexure portions to different thicknesses include using conventional photolithography resist processes to cover and shield portions of the flexure that are not to be plated when other portions of the suspension are being plated. For example, in a flexure having conductors that are to be plated to a first thickness and ground features that are to be plated to a second thickness, the ground feature locations can be masked by resist while the conductors are electroplated with relatively thin nickel and/or gold layers. After the conductors are electroplated, they can be masked with resist, the resist stripped from the ground feature locations, and the ground features electroplated.
Still other known approaches include the use of additional process steps to increase the plating thickness at the locations of the flying leads. For example, following the thin nickel/gold layer plating described above, portions of the conductors other than the flying leads and the locations of the plated ground features can be masked by resist. An additional, and typically relatively thick, layer of gold or other material can then be electroplated onto the flying leads. The plated ground features can then be manufactured in the manner described above. These relatively thick gold flying leads can be manufactured in either encapsulated or non-encapsulated form. FIG. 2 is a cross sectional illustration of a conductive lead 138 having a copper alloy portion 130 with a relatively thin nickel plating layer 132 and a relatively thin gold plating layer 134 that are encapsulated by a relatively thick gold encapsulating layer 136. FIG. 3 is a cross sectional illustration of a conductive lead 148 having a copper alloy portion 140 with a relatively thin nickel plating layer 142 and a relatively thin gold plating layer 144 that are not completely encapsulated by a relatively thick gold layer 146. An advantage of the non-encapsulated lead 148 shown in FIG. 3 is that it requires lesser amounts of gold. But this advantage comes with the disadvantages of additional process steps needed in connection with the masking of the non-encapsulated surfaces, a seam, and associated manufacturing yield impacts.
So-called additive processes are also known and used to manufacture wireless suspensions. However, the plated ground feature manufacturing process described above is generally not suitable for effective use in connection with additive processes of these types.
There remains a need for efficient processes for producing suspension components with electroplated portions or layers having different thicknesses. Such a process that can be incorporated into an additive wireless suspension component manufacturing process would be especially desirable.

SUMMARY OF THE INVENTION

One embodiment of the invention is a method for electroplating a component for a disk drive suspension having first and second opposing surfaces with exposed conductor regions. The method includes providing an electroplating system having a bath of electroplating solution including a plating material and first and second anodes in the bath. The suspension component is positioned in the bath between the first and second anodes. A first electroplating current is applied between the first anode and the exposed conductor regions on the first surface to plate a layer of conductive plating material on the exposed conductor regions on the first surface. A second electroplating current is applied between the second anode and the exposed conductor regions on the second surface to plate a layer of conductive plating material on the exposed conductor regions on the second surface.
Differing currents can be applied between the first anode and the component and the second anode and the component to achieve layers of plating material on the first and second surfaces having differing thicknesses. The currents can differ in magnitude or duration. Additional layers of material having the same or differing thicknesses can be plated onto the component during subsequent passes of the component through the system.
Another embodiment of the invention is a system for simultaneously electroplating portions of opposing first and second surfaces of a disk drive suspension component. The system includes an electroplating container holding an amount of electroplating solution, first and second anodes and structure for supporting the component between the first and second anodes. Power supply means are in electrical communication with the anodes to cause the anodes to produce electrical currents between the anodes and the suspension component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the components of a prior art plating system located in the plating tank.
FIG. 2 illustrates a cross section of a prior art conductive lead plated with a plurality of conductive plating layers having differing thicknesses.
FIG. 3 illustrates an alternative prior art conductive lead having an alternative pattern of conductive plating layers.
FIG. 4 is a schematic representation of a major surface of a suspension component having conductive traces of the type to be plated according to one embodiment of the invention.
FIG. 5 is a schematic representation of an opposing major surface of the suspension component of FIG. 4.
FIG. 6 is a side elevation view of the suspension component taken along line 6-6 of FIG. 4.
FIG. 7A is a schematic representation of the suspension component of FIG. 6 having plating material formed onto opposing surfaces of the traces such that the plating material has differing thicknesses on the opposing surfaces in accordance with one embodiment of the invention.
FIG. 7B is a detailed illustration of a portion of the suspension component of FIG. 7A.
FIG. 8A is a schematic representation of the suspension component of FIG. 6 having plating material formed onto opposing surfaces of the traces such that the plating material has differing thicknesses on the opposing surfaces of the traces according to another embodiment of the invention.
FIG. 8B is a detailed illustration of a portion of the suspension component of FIG. 8A.
FIG. 9 is a schematic representation of a single pass, dual thickness plating system in accordance with one embodiment of the invention, having anodes positioned on either side of a suspension component to simultaneously plate layers of conductive material of differing thicknesses onto two sides of the suspension component.
FIG. 10 is a schematic representation of another embodiment of the plating system of FIG. 9.
FIG. 11 is a schematic representation of still another embodiment of the plating system of FIG. 9 having a plurality of anodes disposed on either side of the suspension component.
FIG. 12 is a schematic representation of another alternative embodiment of the plating system of FIG. 11 having a plurality of power sources attached to the anodes disposed on either side of the suspension component.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 9, a single pass electroplating system 10 capable of providing dual sided, dual thickness plating according to one embodiment of the invention includes a plating container or tank 12 with plating solution 14 located therein. Electroplating system 10 is configured for use in connection with a reel-to-reel electroplating process for plating suspension components such as wireless flexures. Electroplating system 10 includes an unwind member 26, such as a dispensing reel which unwinds a web 20 of material into the tank 12 so that it is in contact with the plating solution. A rewind member 28 such as a receiving reel rewinds the web 20 of material after it has moved through the tank 12. Web 20 is a sheet of materials that includes a plurality of suspension components 40, previously prepared for the plating process of the current invention, as is described below. The web 20 (and suspension components 40) have a first surface or side 22 and second surface or side 24 opposing the first side. The plating solution 14 can include gold for plating selected portions of the suspension components. Alternatively, the plating solution 14 can include other plating materials, such as nickel, silver, copper, palladium, solder materials, or alloys including any of these materials.
A pair of anodes 30 are positioned in the plating solution 14 such that one of the anodes is positioned adjacent the first side 22 of the web 20 and the other anode is positioned adjacent the second side 24 of the web 20. A power source 32, such as a rectifier or other suitable device, is in electrical communication with the anodes 30 via electrical conductors 34. The power source 32 provides electrical signals to each of the anodes 30. The power source 32 can provide the same or differing electrical signals (e.g., the same or different levels, magnitudes, types, and/or duration of signals) to the individual anodes 30. When the power source 32 provides an electrical signal to the anodes 30, the anodes produce an electric current in the plating solution 14. The suspension components 40 of web 20 include exposed conductive material accessible from each of their first side 22 and second side 24, which is described in more detail below. The exposed conductive material functions as a cathode. When current is produced between the anodes 30 and the cathode, conductive material in the plating solution 14 is plated onto the exposed conductive material of web 20.
The thickness of the plating material applied onto the exposed conductive material of suspension components 40 can be controlled by the amount of plating current that flows between the anodes 30 and the exposed conductive material of the web 20 and the length of time that the current is applied to the suspension components. As described above, different portions of the suspension component 40 may preferably include plating having differing thicknesses. Because the current produced by each anode can be applied at differing levels and lengths of time, the plating on exposed conductor surfaces accessible from the first side 22 can have a thicker layer of plating material than exposed conductor surfaces accessible from the second side 24, or vice versa, as desired. Therefore, by controlling the amount of current applied and/or the length of time that the current is applied between the first and second anodes and the web 20, the electroplating system 10 can provide suspension components 40 with varying thicknesses of conductive plating material on different surfaces in a single plating process.
FIGS. 4-6 are schematic representations of suspension component 40 that can be plated by the plating process of the current invention. Conventional or otherwise known processes can be used to manufacture components such as suspension 40. Suspension component 40 can have any of a variety of conventional or otherwise known structures. By way of example, the illustrated embodiment of suspension component 40, prior to being plated, includes a spring metal layer 42 made of stainless steel or other similar materials. A dielectric layer 44 made of polyimide or other suitable materials extends over a portion of the spring metal layer 42 on the first side 22 and conductive leads 46 are formed onto the dielectric layer. Conductive leads 46 can be made of any suitable conductive material, including copper or a copper alloy. Conductive leads 46 have first and second major surfaces 45 and 47, respectively, and two side surfaces 43. The conductive leads 46 are additively applied to the dielectric layer 44 in one embodiment, and the second major surface 47 of the conductive leads contact the dielectric layer. A cover layer 48 is disposed over portions the first major surface 45 and sides 43 of the conductive leads 46 to protect the conductive leads. Those portions of the conductive leads 46 covered by the cover layer 48 are typically not plated. Cover layer 48 can be made of the same or similar materials as dielectric layer 44.
Suspension component 40 can include conductive pads 50, which are portions of conductive leads 46 that are supported by dielectric layer 44 and spring metal layer 42 and are exposed, that is, not covered by cover layer 48. Conductive pads 50 can be located in a variety of locations on the conductive leads 46 and an individual conductive lead can have any number of conductive pads. The conductive pads 50, although shown as having the same width as other portions of the conductive leads 46, can have other widths, sizes, or shapes. Conductive pads 50 can be used to provide electrical communication between the conductive leads 46 and electrical components located either on or external to the suspension component. For example, a conductive lead 46 can be electrically connected to a magnetic head on a slider (not shown), electrical or electronic drive components (not shown) located on or external to the suspension component 40, microactuators (not shown), or other conductive leads.
The illustrated embodiment of suspension component 40 also includes flying leads 52. The flying leads 52 are a portion of the conductive leads 46 uncovered by cover layer 48 and unsupported by the dielectric layer 44 or the spring metal layer 42. The flying leads 52 can extend over an aperture 54 formed through the dielectric layer 44 and the spring metal layer 42. Thus, the second major surface 47 of each of the flying leads 52 is exposed on the second side 24 of the suspension component 40. The portion 56 of the aperture 54 that extends through the dielectric layer 44, in one embodiment, is smaller than the portion 58 of the aperture that extends through the spring metal layer 42 so that the dielectric layer extends over the spring metal layer. Aperture 54 can be formed through a variety of known methods, including, for example, etching the spring metal layer 42 and dielectric layer 44. The suspension component 40 illustrated in FIGS. 4-6 is a schematic representation. Actual components can have other structures such as flexures, gimbals, and spring regions, and multiple features such as conductive pads 50 and flying leads 52. For example, a portion of the conductive lead can extend outside of the width of a component(not shown) and thereby be exposed on both the first side and second side of the component.
FIGS. 7A-B illustrate a suspension component 40 after it is plated in electroplating system 10 according-to one embodiment of the invention. A layer 60 of plating material is applied to the conductive pads 50 and the flying leads 52 on the first side 22 of the suspension component 40. In addition, a layer 70 of plating material is applied to that portion of the flying leads 52 accessible from the second side 24 of the suspension component 40. The layer 70 on the flying leads 52 has a thickness 72 that is greater than a thickness 62 of the layer 60.
Alternatively, the thickness 62 of the layer 60 can be the same or greater than the thickness 72 of the layer 70. As described above, the layers 60, 70 of plating material can include gold, silver, nickel, or alloys thereof. As described above with respect to FIG. 9, the type and duration of electrical signals supplied from the power source 32 to the individual anodes 30 positioned within the plating solution 14 will determine the thickness of the plating material of layers 60 and 70. The sides (43 in FIG. 5) of the conductive pads 50 are effectively plated along with first layer 60. The sides 43 of the flying leads 52 are effectively plated along with layer 60 and/or layer 70 as current leakage from each side will extend to the sides of the flying leads (not shown). As a result, the conductive leads are encapsulated, as layers 60 and 70 extend into plating material on each of the sides 43, thereby leaving no seams on the flying leads 52.
FIGS. 8A-B illustrate a suspension component 240 after it is plated in electroplating system 10 according to another embodiment of the invention. Suspension component 240 includes plating material 260 applied to conductive pads 250 and flying leads 252 on a first side 222 of the suspension component 240. In addition, suspension component 240 includes plating material 270 applied to the second side 247 of the flying leads 252, which are exposed to a second side 224 of the suspension component 240. The plating material 260 includes a first layer 264 and a second layer 266 and the plating material 270 includes a first layer 274 and a second layer 276. The first layers 264, 274 can include one plating material such as nickel or an alloy thereof and the second layers 266, 276 can include another plating material such as gold, silver, copper, palladium, solder materials, or an alloy. In the illustrated embodiment, first layers 264 and 274 have the same thickness. The second layers 266 and 276 are illustrated as having differing thicknesses, both as compared to each other and their respective first layers 264 and 274. However, the thickness of each layer may vary without departing from the scope of the invention. The current produced between the anodes and cathodes within the plating solution can be controlled to determine the thicknesses of the respective layers.
The first layers 264 and 274 are applied to the conductive leads 246 of suspension component 240 by electroplating the layers as shown in FIG. 9 and described above. The plating solution 14 includes the plating material that forms the first layers 264 and 274. After the first layers 264 and 274 have been applied, the second layers 266 and 276 are similarly electroplated onto the suspension component. The second electroplating operation, which includes the plating material that forms the second layers 266 and 276, can be performed in a second plating system similar to that of system 10, with a different plating solution. Additional layers, applied in subsequent plating operations, can be similarly added without departing from the scope of the invention. With the exception of the differences discussed above, the suspension component 240 is similar to suspension component 40 and similar features are identified using reference numbers in the 2XX series.
FIG. 10 illustrates a single pass, dual-sided electroplating system 310 in accordance with another embodiment of the invention. Electroplating system 310 includes a plating tank 312 with plating solution 314. A first anode 330 is positioned in the plating solution 314 adjacent the first side 322 of web 320 and a second anode 331 is positioned in the plating solution 314 adjacent the second side 324 of web 320. First power source 332 is in electrical communication with first anode 330 and second power source 333 is in electrical communication with second anode 331. Separate power sources such as 332 and 333 can provide improved control of the amount and duration of current applied to the first and second sides, respectively, thereby more precisely determining the thicknesses of the layers of plating material applied to the opposing sides of components or portions of components such as described above in relation to component 40. With the exception of the differences discussed above, the electroplating system 310 can be the same as or similar to the electroplating system 10 described above and similar features are identified using reference numbers in the 3XX series.
FIG. 11 illustrates a single pass, dual-sided electroplating system 410 in accordance with still another embodiment of the invention. Electroplating system 410 includes a plating tank 412 with plating solution 414. A plurality of anodes 430 are positioned in the plating solution 414 adjacent the first side 422 of web 420 and a plurality of second anodes 431 are positioned in the plating solution 414 adjacent the second side 424 of web 420. Power source 432 is in electrical communication with the plurality of first anodes 430 and second anodes 431. The plurality of first anodes 430 and second anodes 431 can improve the plating coverage by providing a more consistent current at the exposed conductive portions of the web 420 as the web is dispensed between unwind member 426, and rewind member 428. With the exception of the differences discussed above, the electroplating system 410 can be the same as or similar to the electroplating system 10 described above and similar features are identified using reference numbers in the 4XX series.
FIG. 12 illustrates a single pass, dual-sided electroplating system 510 in accordance with still another embodiment of the invention. Electroplating system 510 includes a plating tank 512 with plating solution 514. A plurality of anodes 530 are positioned in the plating solution 514 adjacent the first side 522 of web 520 and a plurality of second anodes 531 are positioned in the plating solution 514 adjacent the second side 524 of web 520. First power source 532 is in electrical communication with the plurality of first anodes 530 and second power source 533 is in electrical communication with the plurality of second anodes 531. The first and second power sources 532 and 533 can provide improved control of the current flowing from the plurality of first anodes 530 and second anodes 531, thereby further refining the amount and duration of current applied to the web 20. With the exception of the differences discussed above, the electroplating system 510 can be the same or similar to the electroplating system 410 and similar features are identified using reference numbers in the 5XX series.
The invention offers important advantages. It enables the simultaneous electroplating of different portions of suspension components, including portions on different sides of the components to different and independently controlled thicknesses. Fully encapsulated traces can be produced without additional consumption of gold or other plating material. The method is efficient, and can be used in connection with additive manufacturing processes.
Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. For example, the several anodes can be spaced from one another along the length of the web of components rather than being opposite one another as shown in FIGS. 9-12.

Claims

1. A method for electroplating a component for a disk drive suspension, comprising:

providing an electroplating system having a bath of electroplating solution including a plating material and first and second anodes in the bath;

providing a suspension component having first and second opposing surfaces with exposed conductor regions;

positioning the suspension component in the bath of electroplating solution between the first and second anodes;

applying a first electroplating current between the first anode and the exposed conductor regions on the first surface to plate a first layer of conductive plating material on the exposed conductor regions on the first surface; and

applying a second electroplating current between the second anode and the exposed conductor regions on the second surface to plate a first layer of conductive plating material on the exposed conductor regions on the second surface.

1. The method of claim 1, wherein applying the first and second electroplating currents causes the first and second surfaces to be plated with first layers of plating material having differing thicknesses.

2. The method of claim 1, wherein applying the first and second electroplating currents causes the first and second surfaces to be plated with first layers of plating material having about the same thickness.

3. The method of claim 1, wherein applying the first and second electroplating currents includes applying a greater current between one of the first and second anodes and the exposed conductor regions than the current applied between the other of the first and second anodes and the exposed conductor regions.

5. The method of claim 1, wherein applying the first and second electroplating currents includes applying current between one of the first and second anodes and the exposed conductor regions for a longer period of time than the current applied between the other of the first and second anodes and the exposed conductor regions.

6. The method of claim 1, wherein applying the first electroplating current between the first anode and the exposed conductor regions is performed simultaneously with the application of the second electroplating current between the second anode and the exposed conductor regions.

7. The method of claim 1, wherein applying the first and second electroplating currents includes applying the first and second electroplating currents at different times.

8. The method of claim 1, wherein applying the second electroplating current includes applying the second electroplating current after applying the first electroplating current.

9. The method of claim 1, further comprising plating a second layer of conductive plating material onto the first layer of conductive plating material on the first surface and plating a second layer of conductive plating material onto the first layer of conductive plating material on the second surface.

10. The method of claim 9 wherein the second conductive layer on the first surface has a different thickness than the first conductive layer on the first surface.

11. The method of claim 9, wherein the second conductive layer on the first surface has a different thickness than the second conductive layer on the second surface.

12. A system for electroplating portions of opposing first and second surfaces of a disk drive suspension component, comprising:

an electroplating container holding an amount of electroplating solution;

a first anode;

a second anode;

structure for supporting the suspension component between the first and second anodes; and

power supply means in electrical communication with the first and second anodes to cause the first anode to produce a first electroplating current between the first anode and a first side of the suspension component and to cause the second anode to produce a second electrical current between the second anode and a second side of the suspension component.

13. The system of claim 12 further comprising a third anode spaced apart from first and second anodes, wherein the third anode is in electrical communication with power supply means to produce an electrical current between the third anode and one of the first and second sides of the suspension component.

14. The system of claim 12 and further comprising:

a web of material, including the suspension component;

an unwind member for dispensing the web of material into the plating solution; and

a rewind member for receiving the web of material dispensed through the plating solution;

wherein the first and second anodes are positioned between the unwind and rewind members.

15. The system of claim 12 wherein the electroplating solution comprises gold.

16. The system of claim 12 wherein the electroplating solution comprises nickel.

17. The system of claim 12 wherein the electroplating solution comprises silver.

18. The system of claim 12 wherein the electroplating solution comprises copper.

19. The system of claim 12 wherein the electroplating solution comprises palladium.

20. The system of claim 12 wherein the electroplating solution comprises a solder material.