KR890000808B1 - Substrate containing fibers of predetermined orientation and process of making the same - Google Patents

Abstract

microporous elastomer having a work surface and support surface joined by side surfaces. The majority of fibres are oriented primarily transverse to the work surface so that their ends adjacent the work surface are at angles of 45-135 deg. w.r.t it. The fibres are uni-directional and substantially perpendicular to the work surface unifermly distributed throughout the thickness of the article. The article can be a laminate made by bonding a number of individual articles together so that the work surfaces of adjacent articles are coplanar.

Description

A support containing a predetermined array of fibers and a method for producing the same

1 is an enlarged cross-sectional view of a laminated article according to the present invention, broken down at the center, distal end and bottom.

2 is an enlarged cross-sectional view of a portion of FIG.

3 is a side view of a rolled felt wed used to make the support of the present invention.

4 is a plan view of the winding bolt web shown in FIG.

5 is an enlarged plan view of a portion of the felt web of FIGS. 3 and 4 after impregnation with a porous elastomer, showing the direction of the felt fiber and the cut pieces of the impregnated felt web.

6 is a cross sectional view of the impregnated web drawn along line 6-6 of FIG.

FIG. 7 is a perspective view of one of the strips cut from the web of FIG.

8A-F are plan views of various embodiments of disk-type polishing pads using laminated articles according to the present invention.

The present invention relates to an extremely valuable product as a substrate for polishing materials, in particular for polishing semiconductor wafers.

In particular, in the present invention, most of the fibers forming the bolts are arranged mainly transversely with respect to the surface of the product used as the work suface, such as a polishing surface, a bearing surface, etc., so that most of the fiber ends are rubbed. A microporous material consisting of a piece or sheet of fiber felt impregnated with a microporous elastomer, adjacent to the face, in particular the axis of the fiber being at an angle of about 45 ° to 135 ° with respect to the friction surface. The invention also relates to a method of making the novel product.

Typical supports used for abrasive and other operations that may use the products of the present invention include nonwoven pieces or webs of chops made of fibers, such as polyester fibers, impregnated with microporous elastomers such as urethane. Representative examples of prior art structural members include CORFAM (trade name of E.I.du pont de Nemous and Company) and SUBA IV (trade name of Rodel, Inc) microporous material.

In the prior art, the fibers of the impregnated bolt are arranged randomly but are generally mainly parallel to the main plane of the bolt web. The chopped webs used to make prior art microporous materials are produced by well known methods, including needling, to achieve a three dimensional random arrangement of fibers in the web. In practice, however, such three-dimensional random fiber arrangements are rarely made and generally the majority of the fibers are aligned parallel to the plane of the major surface of the web.

In conventional microporous polishing pads, the fibers that hold the pads together and support the soft elastomeric constituent material contribute little to the polishing process, but rather trap trapped abrasive slurry, small particles of the abrasive product from the polishing process, and the like. Trapping tends to interfere with the polishing process. The fibers on the pad surface protect most of the microporous elastomer, the effective abrasive structural member, from the workpiece. It does not polish effectively on the side of the fiber. Prior art polishing pads should be replaced when less than 10% of the pad thickness is used when trapping foreign particles that can actually damage the surface of the product to which the fibers on the surface of the pad are polished.

The surface of the microporous elastomer used for polishing takes the form of a "pumping action". The pressure of the workpiece across the pores on or near the surface of the microporous pad compresses the pores, releasing abrasive sludge and debris consumed as the pad rotates. The pores are then expanded and filled with the polishing slurry. In the pads of the prior art, the pores are filled and the pads are stiff and the rigid area is increased due to the tight or thin horizontal fiber bundles. Therefore, their flexibility is reduced and pumping action is suppressed.

The present invention overcomes these drawbacks and, in particular, significantly improves the prior art microporous materials used as abrasive supports.

As used herein, "adjacent" means that the fiber ends are at or slightly above or below the friction surface.

As used herein, “mainly transversely” means an angle of about 45 ° to about 135 ° with respect to the predetermined surface.

As used herein, “friction surface” refers to the surface of an article of the present invention that acts as a surface in contact with a workpiece, such as an abrasive surface, a load bearing surface, and the like.

The present invention provides a friction surface, a side facing the friction surface, in which the majority of the fibers are arranged primarily transverse to the friction surface such that most of the fiber ends adjacent to the friction surface are at an angle of about 45 ° to about 135 ° with respect to the friction surface. A microporous product is characterized by a gasket sheet of fibers impregnated with a microporous elastic body having a side) face and a support face in contact with the side face.

The present invention also relates to a method for producing a product characterized by the following process: (a) (i) forming a graft sheet made of fibers, in which most of the fibers are arranged in a predetermined arrangement, and (ii) A preform is prepared by impregnating the sheet with a microporous elastomer and then (i) curing the elastomer-impregnated felt sheet; (b) The preform is cut so that the majority of the fibers are arranged primarily transverse to the cut plane forming the friction surface.

In addition, the present invention is well known in the art for conventional carpet manufacturing, such as flocking, or microporous products, and for the majority of the fibers in the support web, such as those used to make cut pile plush carpets. The technique relates to a process for producing a microporous product by arranging mainly transverse to the friction surface of the web and then impregnating the web with the microporous elastomer and then curing it.

The distal end of the predominantly transverse reinforcing fiber in the microporous material of the present invention adjacent or slightly expanded to the friction surface becomes an effective abrasive construction material, rather than a simple reinforcing structural member that tends to be adversely polished. In general, the fibers do not trap spent slurry particles or other debris. Moreover, the distal ends or tips of these fibers are evenly worn and do not stick to the fiber bolts because they are small and easily released from the pads in use. As a result, the new polishing surface of the elastic body is exposed almost continuously.

When the laminated article is formed by joining together a series of pads such that the friction surface is approximately coplanar, like most of the fibers, the bonded adhesive layer is also mainly transverse to the friction surface and in particular almost perpendicular. In this method, in particular the binder made of the same elastomer as used to impregnate the chopped layer, also polishes the polishing surface with a beneficial polishing action.

The microporous product of the present invention may be used as a polishing pad itself or as a polishing slurry used to provide desirable surface finishes for semiconductor wafers, silicon wafers, crystals, glass, ceramics, polymeric plastic materials, metals, stones, and other surfaces. It is extremely suitable for use as a support in the art. The present invention is, for example, bearing or bearing surface; Seals and gaskets; Stripping discs, buffing wheels; Ringer (wri-nger); Washing machine; Brake and grip pads; Printing rollers and printing roller covers, hickey picker; Impact curtain; It has a variety of other uses, including footwear and other garment items, especially waterproof, ventilated items. Thus, while this specification is directed to the use of the invention in polishing applications, this specification is for illustrative purposes only and is not intended to limit the invention to this use only. The present invention will be apparent to those skilled in the art and has other advantages not particularly mentioned above.

DETAILED DESCRIPTION OF THE DRAWINGS In the drawings, like numerals refer to like elements, and the article 10 made according to the invention is shown in FIGS. FIG. 1 illustrates a product 10 bonded to the side by side with an adhesive binder 52, such as products 10 'and 10 ".

The article 10 shown in FIGS. 1, 2 and 7 has a friction surface 12. Products 10 'and 10 "include friction surfaces 12' and 12", respectively (see Figure 1).

Microporous product 10 comprises two essential constituent materials: a fibrous web or mat 14 (shown well in FIGS. 3, 4 and 5) in which the majority of the woven fibers are arranged in a particular direction as described below. ; And porous elastomer 32 impregnating the chopped web or mat 14. Most of the fibers are arranged mainly transverse to the direction in which the friction surface 12 is to be formed.

FIG. 2 is an enlarged view of only a portion of product 10 showing the general arrangement of fibers impregnated with porous elastomer 32. FIG. Most of the fibers, generally designated 16, have a tip 18 of the fiber adjacent to the friction surface, and in general, the vertical axis of the fiber is from about 45 ° (represents the tilted fiber 17) to about 135 ° (tilt) Are arranged transversely with respect to the friction surface 12 so as to form an angle of the fiber). Preferably, the fibers are almost perpendicular to the friction surface 12 when the article is used as a polishing pad or support. Randomly arranged fibers 22 are generally parallel to the friction surface and fibers 24 and 26 at opposite angles are used to produce the product 10 needed to hold the web together, among others in the impregnated web. Represents an array of fibers. The abrasive particles can be mixed in the fiber.

Although polyester fibers are used in the examples described below, various types of natural and synthetic fibers can be used to make nonwoven webs for the microporous materials of the present invention.

Nothing is new concerning the production of elastics, the form of fibers, or the impregnation of webs using elastics. Rather, the invention belongs to a specific arrangement of the fibers in the impregnated felt for producing the product according to the invention.

5 and 6 show the chopped web 14 with the fibers aligned as described above after being impregnated with a suitable elastomer. From there, as best seen in FIGS. 5 and 7, the impregnated web is cut along the transverse axis to form a number of strips 27. The strip is then cut along the line from the web to form a cut plane 28 in the web (FIG. 5). The end face 30 of the cutting strip 27 (FIG. 7) is mated with the cut face 28 of the felt web. Therefore, one basic aspect of the microporous product 10 of the present invention is formed by cutting the impregnated felt web in the transverse axis and arranging it so that the transverse cut surface forms the friction surface 12. Unlike the prior art, in which the friction surface is generally represented as surface 31, surface 31 of the invention represents a side that is not a friction surface.

The base product 10 according to the invention can have a width (W in FIG. 7) corresponding to the thickness of a single piece of impregnated fennel web, while the multiple products such that the friction surface of the laminated product is almost coplanar. It is presently preferred to stack 10 together.

This structure is best shown in FIG. 1, where the laminated product 50 is joined together along side sections 31, 31 ′ and 31 ″ by a binder 52 having an adjacent distal end 54 at or slightly extended to the friction face 12, respectively. Laminated product 10, 10 'and 10 ". The distal end 54 performs an effective polishing function like the distal end 18 of the fiber 16.

The binder 52 should be an elastic adhesive suitable for porous elastomer 32 which impregnates the bolt. In order to produce a representative laminated product 50 according to the invention, when the friction surface 12 is used as an abrasive surface, a support surface, etc., several basic products 10 are laminated together and then the laminate is cut to have a desired arrangement. Processing.

8 shows a top view of various embodiments of the abrasive disk formed from the laminate 50 of the present invention. In each of FIGS. 8A-F, numeral 52 denotes a binder that bonds together strips of article 10, while numeral 10 denotes the article of the invention formed into strips.

Certainly, any combination of these arrangements, or any arrangement of the lamination method, can be used, as long as the majority of the fibers are arranged primarily transversely on the friction surfaces of the product 10 and the laminated product 50. The friction surface of article 10 or laminate 50 is textured, grooved, segmented, embossed, skived, separated, or otherwise The process can be used to promote effective slurry flow and distribution.

The following specific examples illustrate the invention without limiting it.

Example 1

Combining the felt sheet of polyethylene terephthalate fiber with 9 parts of 1.5 denier fibers of about 3.8 cm (1.5 inches) and 2 parts of 2.25 denier fibers of the same length, which were opened and blended with a roller card. It is prepared by combining. The blended fibers are carded and cross-laped into a loosely layered web in a conventional manner. The web is first sent to the needle-weaving machine on one side, and then the other side is a total of 16 passes through the weaving machine until it has a needling density of about 320 punches / cm ² (3,100punches / in. ² ). Needle on each side 8)

A urethane elastomer impregnation solution is prepared as follows. 73.5 parts of polytetramethylene etherglycol of molecular weight 1000 are mixed with 6.4 parts of tolylene-2,4-diisocyanate and dimerized by heating at 90 ° C. (140 ° F.) for 3 hours. 6.4 parts of the resulting dimer are mixed with 18.4 parts of methylene bis (4-phenyl isocyanate) and capped by heating at 80 ° C. (176 ° F.) for 1 hour. The initial polymer with the capped dimer and isocyanate end groups is dissolved in sufficient N, N-dimethylformamide (DMF) to form a 20% solution. Independently, the same solvent prepares a 20% solution of hydrazine hydrate. The two solutions are mixed together to form a 20% elastomer solution. The solution is diluted with DMF to about 9.0% urethane content. Polyvinylchloride (PVC) is dissolved in sufficient DMF to make a 9.0% solution. An elastomer blend solution consisting of 85% polyurethane solution and 15% PVC solution is made.

The web is immersed in a 9.0% blend solution of elastomer at 23.8 ° C. (75 ° F.) and nearly saturated with the solution. The impregnated web is immersed in water at about 23.8 ° C. (75 ° F.) until the elastomer solidifies throughout the web to uniformly solidify the elastomer throughout the web-tight fiber structure. The impregnated web is washed with water until there is little solvent and then dried. The resulting dry, microporous web has a thickness of about 0.5 cm (0.2 inch).

As a result of carding and cross-lapping, the main fiber arrangement is transverse to the machine direction of the web. The web is then cut along the machine direction into strips about 2.54 cm (1 inch) wide so that the predominant fiber arrangement is primarily transverse to the cut plane of the strip that will form the friction surface.

Adhesives that join the strips of impregnated webs together are made and processed using the same materials to produce urethane elastomers, except that the concentration of the adhesive solution is increased by about 25%. Apply about 0.025 cm (10 mile) thick film of adhesive over the major surface of the strip. The adhesive coating strip is then spiraled until it is about 56 cm (22 inches) in diameter. Spiral was squeezed sufficiently so that the adjacent surfaces of the strips were completely compressed with each other and a small amount of adhesive was pushed out of the inner surface.

During curing of the adhesive, the spiral may be held in place by any suitable method such as a circumferential wrap of fiberglass reinforced adhesive tape or a steel banding strap.

The spiral is then cured by baking in a well ventilated oven at 120 ° C. (248 ° F.) for 6 hours. After curing, the spiral is aged for 24 hours before cooling and removing the compression wrap.

Spiral is cut into thin sheets of 0.25 cm (100 miles) thick to make a polishing pad. The pad has the shape shown in FIG. 8C.

The thinly cut pad is attached to a STRASBAUGH 6CA polisher and used to pre-polish the silicon wafer. The pad was found to polish the material 20% to 60% faster than the standard pad. The surface characteristics and plan of the wafer were excellent.

Example 2

The impregnated felt web is prepared in the same manner as in Example 1 and is likewise cut into strips of 2.54 cm (1 inch) wide.

Cut the strip 1 meter (39.4 inches) long. Then, the main surface of each length was coated with an adhesive in the same manner as in Example 1. About 200 adhesive coated strips are faced in a framing press and sufficient pressure is applied so that the faces of each strip are in complete and intimate contact with the faces of the adjacent strips. The entire aggregate is then stored for 6 hours in a 110 ° C. (230 ° F.) hot air oven. After cooling, the laminated product is taken out of the press.

A pad having the shape generally shown in 8a or 8b is cut thin from the laminated product and attached to the grinder in the same manner as in Example 1. In fact, this pad was found to be somewhat superior to the pad of Example 1. Since the pads of Examples 1 and 2 are the same except for the lamination method, the improvement is believed to be due to the arrangement of the adhesive lines to the wafer to be polished.

In the pad of Example 1, the line between the adhesive and the ply is essentially cylindrical. When the pad is rotated in an abrasive environment, the bond line moves to some extent on the workpiece in the direction of motion. In contrast, the adhesive line of Example 2 is straight and parallel to one row of pads. Workpieces that are polished or wrapped on the pad of Example 2 cross the lines of the adhesive at all angles. This effect appears to further enhance the performance of the fiber pad of the present invention.

Example 3

In this embodiment a single pad is made from a single web of fibers arranged vertically.

A carpet manufacturing method similar to the method used to make short-cut pile flush carpets is mainly used to make webs in which the transverse fibers are arranged perpendicular to the horizontal friction surface.

For this example, a reinforced sheet that is vertically aligned by needle punching 239.2 g / m ² (7 ounces per square yard) of short polyester fiber to one side of 114.3 g (4 ounces) of lightweight polyester scrim To prepare. The fibers used were 2.2 denier crimped fibers, 1.5 inches long. As a result of needle punching, entangled bolts are made on one side of the scrim with the main arrangement of the bolt fibers in the vertical direction. The total thickness of the fiber support is 0.178 cm (0.070 inches).

A microporous binder solution was prepared by dissolving 16% by weight of Estane 5707 (polyurethane trademark of B.F.Goodrich Company) in DMF. As in the previous example, the web fibers are saturated with binder solution, solidified in water, washed and dried.

At this time, the thickness of the material is about 0.165 cm (0.065 inch). The top surface of the material is buffed to remove about 0.025 cm (0.010 inch) of the “skin” formed during the solidification process.

The product is cut with a polishing pad and the back side (fiber side) is attached to the polishing machine platen using a double sided adhesive such as adhesive 442 (trade name of Minnesota Mining and Manufacturing Company).

The polishing rate of the pads of this example is somewhat less than that of Example 2, but is significantly better than the control pads of the prior art. However, because the pad of the third embodiment is economical, it is quite easy to manufacture and low in cost.

Claims (16)

Impregnated with a microporous elastomer with a friction surface, characterized in that the majority of the fibers are arranged primarily transverse to the friction surface such that most of the fiber ends adjacent the friction surface are at an angle of about 45 ° to about 135 ° with respect to the friction surface. Microporous product consisting of felt sheet of woven fiber. The microporous product of claim 1 wherein the fibers are substantially perpendicular to the friction surface. A microporous product according to claim 2 wherein the elastomer consists of polyurethane and the fibers consist of polyester. The microporous article of claim 1 wherein the elastomer is made of polyurethane and the fibers are made of polyester. The microporous article of claim 1 wherein the fibers arranged primarily transverse to the friction surface have a nearly uniform distribution throughout the thickness of the article. A laminated article consisting of a plurality of articles according to claim 1 joined and arranged together such that the friction surfaces of adjacent articles are approximately coplanar. 7. The laminated article of claim 6, wherein the elastomer is made of polyurethane and the fibers are made of polyester. The laminated article of claim 7, wherein the articles are joined together by an elastic adhesive suitable for the polyurethane of the article. 8. A laminated article according to claim 7, wherein the articles are joined by the same polyurethane as the polyurethane of the article. The article of claim 1 further comprising abrasive particles mixed in the fiber. Wherein the majority of the fibers forming the preform are arranged primarily transverse to the frictional surface of the preform, the preform is impregnated with the microporous elastomer, and then the elastomer is cured. Preparing a preform by forming a graft sheet made of fibers with most of the fibers arranged in a predetermined arrangement, impregnating the graft sheet with a microporous elastomer, and then curing the elastomer impregnated bolt; The preform is cut such that the majority of the fibers are arranged primarily transversely with respect to the cutting plane forming the friction surface such that a predetermined arrangement is made such that most of the fiber ends adjacent the friction surface are at an angle of about 45 ° to about 135 ° with respect to the friction surface. To produce a microporous product. The method of claim 12, further comprising joining together a plurality of cut products such that the friction surfaces of adjacent products are approximately coplanar. Wherein the majority of the fibers forming the preform are arranged primarily on the frictional surface of the preform, and the preform is impregnated with the microporous elastomer, followed by curing the elastomer. Preparing a preform by forming a graft sheet made of fibers with most of the fibers arranged in a predetermined arrangement, impregnating the graft sheet with a microporous elastomer, and then curing the elastomer impregnated bolt; The preform is cut such that the majority of the fibers are arranged primarily transversely with respect to the cutting plane forming the friction surface such that a predetermined arrangement is made such that most of the fiber ends adjacent the friction surface are at an angle of about 45 ° to about 135 ° with respect to the friction surface. Characterized in that the prepared microporous product. 16. The article of claim 15 further laminated by joining together a plurality of cut articles such that the friction surfaces of adjacent articles are approximately equal planar.

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