METHOD TO ENHANCE POLISHING PERFORMANCE OF ABRASIVE CHARGED STRUCTURED POLYMER SUBSTRATES
The intersection of discrete polishing islands staggered in a curvilinear shape with a workpiece maintains a substantially uniform film thickness throughout the polishing operation and also leading to a stable polishing operation due to the substantially invariant pressurization.
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This application claims the benefits of the filing date of U.S. Provisional Patent Application Ser. No. 61/315,210 filed Mar. 18, 2010, which is entitled “Method to Enhance Polishing Performance of Abrasive Charged Structured Polymer Substrates” and U.S. Provisional Patent Application Ser. No. 61/315,237 filed Mar. 18, 2010, which is entitled “Method to Enhance Polishing Performance of Abrasive Charged Polymer Substrates” both of which are hereby incorporated herein in their entirety by reference.
FIELD OF THE INVENTIONThe present invention is directed to a method and apparatus for an abrasive article with a plurality of polishing islands arranged to generate a constant contact area during polishing.
BACKGROUNDPolishing with polyamide or other polymer based substrate materials requires maintaining a constant hydrodynamic film for stability during the polishing operation and reducing the required hydrodynamic film is attainable by manufacturing a very large number of grooves into the polymeric film. Grooving of the polymeric film causes a reduction in the bearing area to enable interference between the diamond particles and the bar. The intersection of discrete polishing islands staggered in a curvilinear with a workpiece maintains a substantially uniform film thickness throughout the polishing operation and also leads to a stable polishing operation due to the substantially invariant pressurization.
The current method of polishing a magnetic slider bar onto a polyamide film populated with diamond abrasives attached to a lapping machine yields high localized deformation of the polymer substrate due to the large load required to overcome the hydrodynamic film formed by the lubricant during the lapping process. The dilemma of using a flexible substrate with the current state of the art lapping tools requires large loads to overcome the separation created by the hydrodynamic film formed due to the high shear viscosity of the lubricant and the bar geometry. To overcome the hydrodynamic film thickness and increase the interference between the bar and the polishing agent (substrate charged with diamonds) a large load is applied to the bar. The large load creates large deformation on the soft polymer causing edge rounding of the bar during the lapping process.
Hydrodynamic film lubrication is desired to enhance the mechanical stability of the bar during the polishing however, if the hydrodynamic film thickness reaches a height greater than the diamond protrusion height polishing action is substantially reduced. So a balance between the hydrodynamic film thickness and the hydrodynamic pressure must be achieved to enhance polishing and also maintain a stable polishing operation. Mechanical stability maintains a chatter free operation and a predictable spacing between the bar and the polishing article. So maintenance of the mechanical stability is a must for a successful operation.
The following U.S. Pat. Nos. 6,277,160, 6,155,910, 6,322,652, and 7,300,479 show methods for fabricating structured abrasive on a flat carrier sheet of polyamide. The structured abrasive is formed of adhesive and diamond slurry cured on the carrier sheet. The structured abrasives are arranged in various configurations ranging from squares, trapezoidal, and rectangles. The arrangements proposed in prior art defined by the abovementioned patents do not conserve a constant hydrodynamic film under the bar during the polishing process. The uniform configurations shown in these patents and various sales brochures do not preserve a constant hydrodynamic lift during the polishing process.
The traditional approach, as depicted in
Another way to reduce the required applied load to cause desirable hydrodynamic spacing between the lapping bar and the diamond charged polyamide is discussed below. The solution includes reducing the film thickness generated by the shearing of the lubricant during the polishing process. Discrete sets of patterned islands are fabricated in the diamond charged substrate travel underneath the lapping bar causing a uniform hydrodynamic film regardless of the bar location on the substrate. A series of discrete islands are staggered and arranged to expose a substantially constant area under the slider bar. A novel island pattern organized to form a uniform film independent of bar location is presented. The uniform hydrodynamic film is maintained by maintaining a substantially uniform average pressure and a substantially uniform pressure center location as the bar moves with respect to the substrate. Discrete islands of the substrate cause substantial pressure side leakage to reduce the hydrodynamic pressure countering the applied preload.
Disclosed herein is the use discrete patterns arranged such that the slider bar is exposed to a substantially constant area of the polyamide. A polishing article 400 with staggered series of grooves 401, 402, and 403 repeating with a desired frequency is shown in
Polishing islands offer a substantial reduction in pressure buildup due to the side leakage generated at the leading, trailing and side edges of the island. The curvilinear configuration shown in
Polyamide or other polymer based substrate materials require maintaining a constant hydrodynamic film for stability during the polishing operation and reducing the required hydrodynamic film is attainable by manufacturing a very large number of grooves into the polymeric film. The intersection of discrete polishing islands staggered in a curvilinear shape with a workpiece maintains a substantially uniform film thickness throughout the polishing operation and also leading to a stable polishing operation due to the substantially invariant pressurization.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these inventions belong. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present inventions, the preferred methods and materials are now described. All patents and publications mentioned herein, including those cited in the Background of the application, are hereby incorporated by reference to disclose and described the methods and/or materials in connection with which the publications are cited.
The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present inventions are not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.
Other embodiments of the invention are possible. Although the description above contains much specificity, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the inventions. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of at least some of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.
Thus the scope of this invention should be determined by the appended claims and their legal equivalents. Therefore, it will be appreciated that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem ought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.
REFERENCES
- Roche, S., Bec, S. and Loubet, J. L.: Analysis of the elastic modulus of a thin polymer film. Mat. Res. Soc. Symp. Proc. 778, 117-122 (2003)
- Bec, S., Tonck, A., Georges, J. M., Coy, R. C., Bell, J. C. and Ropper, G. W.: Relationship between mechanical properties and structures of zinc dithiophosphate anti-wear films. Proc. R. Soc. Lond. A 455, 4181-4203 (1999)
- Demmou, K., Bec, S., Loubet, J. L. and Martin, J. M.: Temperature effects on mechanical properties of zinc dithiophosphate tribofilms. Tribology International 39(12), 1558-1563 (2006)
- Bec, S., Tonck, A. and Loubet, J. L.: A simple guide to determine elastic properties of films on substrate from nanoindentation experiments. Philosophical Magazine A 86(33-35), 5347-5358 (2006)
Claims
1. An abrasive article for polishing a surface of a workpiece, the abrasive article comprising:
- a plurality of polishing islands arranged to interact with a workpiece to maintain a substantially constant contact area; and
- abrasive features associated with at least some of the plurality of polishing islands, the abrasive features applying cutting forces to the work piece during motion of the abrasive article relative to the workpiece.
2. The abrasive article of claim 1 wherein the plurality of polishing islands form a curvilinear repeating and staggered arrangement for rotary polishing operations.
3. The abrasive article of claim 1 wherein the plurality of polishing islands form a repeating and staggered island pattern for linear operations.
4. The abrasive article of claim 1 wherein the plurality of polishing islands are arranged in a curvilinear form along the center of rotation of a circular polishing pad.
5. The abrasive article of claim 1 wherein the plurality of polishing islands are pads arranged in a curvilinear form for a rotating pad.
6. The abrasive article of claim 1 wherein the plurality of polishing islands are pads arranged at an oblique angle with respect to the workpiece.
7. An abrasive article for polishing a workpiece, the abrasive article comprising:
- a plurality of polishing islands arranged to intersect with a workpiece to maintain a substantially constant contact area, wherein at least some of the polishing islands include a first surface engaged with the workpiece, and a second surface, attached to a polyamide substrate; and
- the plurality of polishing islands arranged in a cascade arrangement so as to cause a substantially invariant hydrodynamic film under the workpiece during motion of the abrasive article relative to the workpiece.
8. The abrasive article of claim 7 wherein the first surface includes an abrasive feature comprising one or more of
- a nano-scale roughened surface coated with a hard coat,
- nano-scale diamonds attached to a trailing edge of the first surface,
- an abrasive particles attached to a film, or
- an abrasive composite.
9. The abrasive article of claim 7 wherein the polishing pads include abrasive portions having a plurality of different lengths as measured along a direction of motion of the abrasive article relative to the substrate.
10. An abrasive article for polishing a workpiece, the abrasive article comprising:
- a first polishing island:
- a second polishing island; and
- a non-straight link connecting the first polishing island and the second polishing island.
11. The abrasive article of claim 10 further comprising a substrate of a polyamide material, the polyimide material coupled to the first polishing island and the second polishing island.
12. The abrasive article of claim 10 further comprising a sponge like pad coupled to the first polishing island and the second polishing island, a preload placed onto the workpiece via a sponge like pad.
13. The abrasive article of claim 10 wherein the first polishing pad and the second polishing pad are arranged in a curvilinear form along the center of rotation of a circular polishing pad.
14. The abrasive article of claim 10 wherein the first polishing pad and the second polishing pad are arranged at an oblique angle with respect to the workpiece.
15. An abrasive article for polishing a surface of a workpiece, the abrasive article comprising:
- a plurality of polishing islands arranged to intersect with a workpiece to maintain a substantially constant contact area;
- at least some of the plurality of polishing islands connected to other polishing islands with a non-straight link; and
- a polishing substrate containing abrasive features applying cutting forces to the work piece during motion of the abrasive article relative to the slider bar.
16. The abrasive article of claim 15 including a curvilinear repeating and staggered polishing island arrangement for rotary polishing operations.
17. The abrasive article of claim 15 including a repeating and staggered island pattern for linear operations.
18. The abrasive article of claim 15 wherein the polishing pads are arranged in a curvilinear form along the center of rotation of a circular polishing pad.
19. The abrasive article of claim 15 wherein the polishing pads are arranged in a curvilinear form for a rotating pad.
20. The abrasive article of claim 15 wherein the polishing pads are arranged at an oblique angle with respect to the workpiece.
Type: Application
Filed: Mar 17, 2011
Publication Date: Mar 15, 2012
Applicant: BOUTAGHOU LLC (North Oaks, MN)
Inventor: Zine-Eddine Boutaghou (North Oaks, MN)
Application Number: 13/050,577
International Classification: B24D 11/00 (20060101);