KR20170018479A - Semiconductor manufacture component - Google Patents

Abstract

Methods of making compacted or compacted composite articles comprising polymers, especially fluoropolymers and oriented carbon fibers, are disclosed herein and are suitable for use in chemical-mechanical applications.

Description

[0001] SEMICONDUCTOR MANUFACTURE COMPONENT [0002]

The field of the invention includes a method of making reinforced graphite fibers and composites comprising fluoropolymers, which are used in the manufacture of semiconductor manufacturing components.

Composite articles comprising or consisting of a polymer (usually a continuous phase, possibly including fluoropolymer (s)) and fibers (such as glass fibers, carbon fibers, and graphite fibers) are well known in the art have. The fibers may be added to the matrix polymer to improve certain properties of the polymer. Such properties may include creep resistance, tensile strength and tensile modulus, flexural strength and flexural modulus. The reinforcing fibers selected generally have a higher tensile modulus and tensile strength than the polymer alone. As described herein, when a fluoropolymer is used as a matrix polymer, the resulting composite often has a number of properties of the fluoropolymer, such as, for example, hyperthermal and chemical resistance, Making it useful as a component for the industry. It is an object of the present invention to provide a method for producing such a polymer composite exhibiting improved properties and to provide articles prepared by the method.

Background information on the production of polymers and composites of fibers or fibers can be found in Polymeric Materials Encyclopedia, by Joseph C. Salamone (July 23, 1996), ISBN-10: 084932470X, ISBN-13: 978-0849324703 pages 8327- 8343].

Some background of dual-belt press lamination is described in the article "Modeling heat transfer in thermoplastic composites manufacturing: double-belt press lamination by A. Trende, BT Astrom, A. Woginger, C. Mayer, M. Neitzel, : Applied Science and Manufacturing, Volume 30, Issue 8, August 1999, Pages 935-943.

Known methods and articles of the invention include those described in U.S. Patent No. 5,470,409 to Deakyne et al., Entitled " Process for Making Fluoropolymer Composites, " filed November 28, 1995, U.S. Patent No. 5,232,975 issued on August 3, 1993, entitled " Preconsolidation Process for Making Fluoropolymer Composites, " entitled "Tetrafluoro U.S. Patent No. 4,163,742, Mansure, issued Aug. 7, 1979, entitled " Process and product prepared from tetrafluoroethylene polymer and graphite fibers, " U.S. Patent No. 5,427,731 to Chesna et al., Issued June 27, 1995, entitled " Compression molding of structures, " The sealing element "(Sealing elements for compressor valves) which includes call US Patent No. 7,011,111, such as a speaker posts (Spiegl), issued March 14, 2006, but not necessarily limited thereto.

Further known methods and articles of the invention are described in " Glass-fiber-containing nonwoven polymer webs and processes for preparing " U.S. Patent No. 5,759,927 to Meeker and entitled " Method and Apparatus for Making Highly Densified Sheets ", filed October 24, 1995, entitled " But are not necessarily limited to, U.S. Patent No. 5,460,764 to Held.

Simplified manufacturing process; A robust / robust or reproducible manufacturing process capable of producing robust / robust or reproducible products; Producing an article of increased density; Articles of increased density; In the case of a process comprising a solvent or water, producing a product having less metal, metallic, ionic or related impurities; A process for using fibers to maintain fiber length; Producing a product having uniform properties across the useful volume; (E.g., tensile strength, compressive strength, or elongation at break) of uniform or superior (or uniform or superior in one direction, or uniform or superior in two orthogonal directions) regardless of the direction of measurement The need for any one or a combination of improvements including but not limited to any process, including, but not limited to,

Such improvements are sought in fields where composite articles are used, for example, equipment for semiconductor manufacturing, aircraft parts, automobile parts, gaskets, seals, and the like.

≪ 1 >
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of some mats of the known art.
2,
2 is an elevational view of a mat and two composite articles according to the present invention.
DISCLOSURE OF THE INVENTION
(a) from about 70% to about 90% by weight of a thermoplastic polymer;
(b) from about 10 to about 30 weight percent of chopped carbon fibers;
(c) 0.001 to about 10% sizing agent selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, copolyvinyl alcohol, copolyvinyl acetate, copolyvinyl alcohol-acetate and sodium carboxymethyl cellulose. (a), (b) and (c) further comprising (d) less than 2000 nanomoles per gram of combined sodium, potassium, calcium, and aluminum, Wherein each weight percent is based on the total weight of the part is disclosed herein.

A process for making a composite article of density Dc comprising polymers and fibers is disclosed herein. The process disclosed herein comprises providing a mat comprising from about 1 to about 91 weight percent of fibers and from about 9 to about 99 weight percent of said polymer. The mat has a density of Dm smaller than Dc, and the polymer has a predetermined softening temperature. While the at least a portion of the mat is at a temperature below the softening temperature, the mat is densified by compressing it to a density greater than 1.1 times Dm and less than 0.999 times Dc to provide a compacted mat. Thereafter, the compacted mat is generally heated to a temperature above the softening temperature to provide a pre-compacted mat, while the compacted density is greater than 1.1 times Dm and less than 0.999 times Dc.

At least a portion of the pre-consolidated mat is cooled to a temperature below the softening temperature to provide a consolidated mat. The next step is to laminate a plurality of consolidated mats in the height direction to provide a non-consolidated article. The non-compacted article is then compacted by compressing the height of the non-compacted article and generally heating the article to a temperature above the softening temperature to provide a consolidated compact article. At least a portion of the consolidated composite article is cooled to a temperature below the softening temperature.

In certain embodiments, the present invention contemplates combinations of elements known in the art in a novel way to achieve one or more unexpected or unpredictable results, possibly including an unexpected or unpredictable combination of results have. Single elements of such a technology are described in U. S. Patent Nos. 5506052, 6066395, 20090062426, 7094468, 7150913, 5589055, 4420512, 4975321, 4555446, 52272385, 4448910, 4,455,343, 20070082199, 6444187, 4,448,911 or 5236982, or combinations thereof, the disclosures of both of which are incorporated herein by reference.

The density of the composite article is determined according to ASTM D 792-08 Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement of Density and Specific Gravity (Relative Density) Can be measured. The thickness of the mat can be measured by TAPPI T411 for the thickness (caliper) of the paper, the cardboard and the combination board, and the weight per volume is determined by the known size (for example, 16 cm x 16 cm) and TAPPI T411 The area of the thickness measured by the above method can be cut, and the mat of such known volume can be weighed and measured.

Typical matrices of polymer flakes or particles and fibers (17 ' of Fig. 1a or 17 ' in Fig. 1) or composite articles may have a density of from about 0.2 g / ml or less to about 1.9 g / To some extent. A typical compacting mat (17 " in Figure Ic) of polymer flakes or particles in combination with the fibers should have a density greater than the matte used to make it and have a density of about 0.3 g / ml to about 2.9 g / Which is to some extent dependent upon the weighed density of the polymer and fiber used. Figures 1A-1D illustrate the prior art and help to understand the present invention. Figure 1a shows a mat 17 comprising polymer particles 102 and fibers 101 positioned between two platens 60, 62. The release films 61 and 63 may be selectively positioned between the two platens 60 and 62 and the mat 17 composed of the fibers 101 and the polymer particles 102 or the platen may be placed on the platen May be optionally treated differently to prevent sticking. Optionally, the mat 17 may initially be under low contact pressure from the platen, for example because the mat is heated through the platen. When the softening temperature of the polymer is exceeded, the polymer particles will soften and typically change shape. Figure Ib shows a mat that can be obtained when the temperature exceeds the softening temperature and when the beads 102 are formed on the fibers (optionally wetting the fibers) in the layer 17 '. Not all of the original polymer particles need to be heated above their softening temperature. Pressure is applied to the platen 60, 62 as illustrated in Fig. 1c for the change in density to provide a matted mat 17 "that is generally densified at a temperature that is even higher than the softening temperature of the polymer, (Optionally, the mat can be densified or compressed). Since the mat as illustrated is relatively unrestrained at the edge of the platen, i.e., in the in-plane direction, The fibers can move in such a direction with the polymer such that the fibers are aligned more perpendicular to the height direction of the mat (this height direction is the z direction) and more parallel to the platen surface.

Since the polymer-fiber mix during any densification may not be constrained in the plane, a compressive force perpendicular to the z-axis is not necessary and buckling does not need to occur. Optionally, the consolidated mat may be cooled under pressure, especially below the softening temperature. This same sequence of events can be continuously achieved using a heated belt press or similarly a heating zone and a nip roll. This process may include heating the polymer at some point above the softening temperature; This can occur before or after applying pressure to create a significant densification. The composite can be cooled under pressure.

The belt press pre-compacting mat (or debulked ply) leads to a very flat product as compared to conventional platen press pre-compacting / deblocking ply methods. A very flat ply makes it easy to load the debubbled ply for the forming step.

Significant densification is intended to mean densification at a density of less than the desired density but at least 10% greater than the initial density. For example, if the initial density of the mat is about 0.586 g / ml and the desired density of the composite article made from a single mat or stack of such mats is 2.1 g / ml, 50% densification Is a density of 0.586 + [0.50 * (2.1-0.586)] = 1.343 g / ml.

The consolidated mat 17 '' of FIG. 1C can be further consolidated as described above to form the more dense mat or composite article 17 '' 'of FIG. 1d. The apparatus used for further consolidation may be the same or different from the apparatus used for initial consolidation.

Figure 2 shows an elevation view of two composite articles comprising an oriented mat and such oriented mat. Figure 2a shows an oriented mat 2001, where the fibers are shown as being buried for clarity. The coordinate axis setting x-y-z 2002 is defined such that the height of the mat is oriented parallel to the z-axis. Since the fibers 2003 are aligned along one direction perpendicular to the z-axis on average, the direction can be designated to correspond to the x-axis. The y-axis is perpendicular to the z-axis and the x-axis.

The mat illustrated in FIG. 2A was cut from a larger mat to make two cut planes 2006, 2007 parallel to the z-axis and parallel to the y-axis and x-axis, respectively. By such a cut, the observer can see that the fibers 2004 can be cut into a relatively circular cross-section by the xz facets 2006, and the fibers 2005 can be cut by the xz facets 2006 into relatively elliptical cross-sections (or, ultimately, Parallelograms).

Figure 2b shows a portion of an oriented composite article that can be produced by laminating the mat corresponding to Figure 2a. The composite article may have an orientation in which the matrices (e.g., 2022, 2023) are in a different orientation, e.g., parallel to each z-axis (stacked in a height direction) and the fiber orientation of each immediately adjacent, . If a mat is produced by consolidating two thin mats so that the fiber orientation to be stacked is perpendicular, such mat or similar mat may be stacked (stacked in a height direction) parallel to the z-axis, respectively, to obtain the composite article of Figure 2b have. When a mat is produced by consolidating two mats so that the fiber orientation to be laminated is parallel to obtain a thicker mat, such consolidated mats or similar mats are apparently parallel to the z axis respectively to obtain the composite article of Figure 2b (Stacked in the height direction).

Figure 2C shows a portion of an oriented composite article 2030 that may be produced by laminating mat (e.g., 2031, 2032) corresponding to Figure 2A. Note that a plurality of mats are classified into groups 2037, 2039, and 2035 (where a plurality is a triple mat). Some mats are oriented parallel and some are oriented at right angles. Such a composite article shows a lamination pattern which can be called an orientation pattern of 0 degree, 0 degree, 0 degree, 90 degree, 90 degree and 90 degree.

The mat may be made by any known technique. For example, using a papermaking process, the fibers can be mixed with the polymer to form a mixture or slurry. Preferably, the fibrous component comprises from about 0.001% to 5% of consistency or solids content (e.g., from 99.009 to 95 parts of water or from 0.01 to 5 parts of solids in water or water), although any mixing means may be used. ). The slurry may then be diluted with water and finally flocculated using a flocculating agent and drainage retention aid chemical to enhance formation. The agglomerated mixture or slurry may then be formed into a wet mat, perhaps in a papermaking process, oriented in the direction of movement of the mat, or possibly on a papermaking machine, with orientation of the fibers normal to that direction or without orientation of the fibers . Alternatively, the mat may be formed by vacuum casting the slurry or by other methods. The mat may be formed, for example, by dewatering the slurry using a belt press. Belt presses are manufactured by Bright Technologies of Hopkins, Michigan, USA. The mat may be dried, for example, in an oven, on a rotating drum, or by moving air. For a more detailed description of some standard papermaking techniques that may be used, see U.S. Patent No. 3,458,329, the disclosure of which is incorporated herein by reference.

The densification may be performed by compression or other known methods, which may be performed simultaneously or sequentially on one or more axes. The axes may be orthogonal to one another, such as the x, y, and z axes.

The mat may have any convenient length dimension, width, or height. The mat may have a height greater than one centimeter, or the height may be less than 0.8, 0.6, 0.4, 0.2, 0.1, 0.05, or 0.01 centimeters.

The densification can be performed at a pressure as low as 100 psi and as high as 100 MPa, and at an intermediate pressure between about 100 psi and about 100 MPa.

Densification, heating, cooling, or a combination thereof may be performed for about 0.1, 1, 2, 5, 10, 20, 100 minutes or hours to about 135 hours or more.

Any densification method may and may break at least a portion of the fiber during processing. Therefore, the length of the fibers can be reduced. It is usually advantageous to maintain a long fiber length, but this can advantageously be compromised for certain applications if other properties of the composite article are improved.

The mat may be made by other means, for example dry air laying, which selectively uses existing polymer particles. The mat may be densified by dry needling. Some aspects of matte technology are provided in U.S. Patent No. 6,855,298, the disclosure of which is incorporated herein by reference.

The polymer of the present invention may be a fluoropolymer, and any polymer of the present invention may include tetrafluoroethylene, perfluoro (alkoxyalkanes) of 3 to 14 carbon atoms, such as perfluoro ), Hexafluoropropylene, chlorotrifluoroethylene, ethylene, propylene, or a combination (copolymer) thereof.

Any polymer of the present invention may optionally flow upon heating, especially above the polymer melting point or above the glass transition temperature (Tg). The polymer can selectively wet the fibers, especially after softening.

Polymers useful in the present invention are thermoplastic polymers and are present in an amount of from about 70% to about 90% by weight, based on the total weight of the part.

The softening temperature of a polymer is typically the temperature at which the polymer can be slowly but permanently deformed without breaking, chipping or separating. Examples of the softening temperature include a melting point, a minimum temperature of the melting range, a maximum temperature of the melting range, or a glass transition temperature.

The particles are small pieces or pieces, or small pieces or flecks. The particles may be free flowing or adhered to the fibers. Types of particles include flakes, grains, shreds, fragments, crumbs, chips, pellets, specks, shaving, etc. .

Fiber is glass; black smoke; carbon; Fluorinated graphite; Aramids, such as poly (p-phenylene terephthalamide); Boron nitride; Silicon carbide; Polyester; And polyamides. Carbon, graphite and fluorinated graphite fibers are preferred fibers. The fibers of the present invention can also be chopped.

The median length of the fibers may be longer or shorter or equal to the median height of the mat comprising the fibers.

The fibers may be sized as known in the art. The sizing may be carried out, for example, using an epoxy resin or polymer, a urethane-modified epoxy resin or polymer, a polyester resin or polymer, a phenolic resin or polymer, a polyamide resin or polymer, a polyurethane resin or polymer, Polyetherimide resins or polymers, polyamideimide resins or polymers, polystyrylpyridine resins or polymers, polyimide resins, bismaleimide resins or polymers, polysulfone resins or polymers, polyethersulfone resins or polymers, Epoxy-modified urethane resins or polymers, polyvinyl alcohol resins or polymers, polyvinylpyrrolidone resins or polymers, resins or polymers and mixtures thereof. The sizing can be solvent compatible or water soluble, solvent soluble or water soluble. Polyvinylpyrrolidone (PVP), a known sizing agent, is a water soluble polymer made from the monomer N-vinylpyrrolidone. Known sizing agents are described in U.S. Patent Application Publication Nos. 20080299852; U.S. Patent Nos. 5,393,822 and 7,135,516.

One method for the production of polymer-fiber composites involves co-dispersing a thin polymer flake having some irregular fibrous structures extending from the irregular periphery. Flakes and fibers used to make mats by the papermaking technique or co-dispersed in water may have a test maximum of Canadian Standard Freeness of greater than 200 or even a maximum of 2000 freeness. Flakes used to make mats by the papermaking technique or flakes and fibers that are co-dispersed in water can have a settling time of 1 to 13,000 seconds or more. The settling time is optionally measured in an aqueous solution using a fiber content weight ratio used for the mat (i.e., the time required for the screen to ultimately form a mat that is observed until such a time that a new layer is formed on the bottom or top, Less than 1% based on the weight of polymer solids suitable for forming an apparently homogeneous slurry suitable for the following. The settling time may be greater than about 2 seconds to about 12,000 seconds.

In certain embodiments, most of the water is removed from the mat to form a wet mat; Further removing water from the layer to form a dry mat; Drying the layer to form a self-supporting flat mat; Optionally, the web is thermally tacked to improve the dry strength for handling and pre-consolidating the mat by heating the mat above the polymer melt temperature to form a different mat, and then applying sufficient pressure to the mat Applying it perpendicular to the plane to cause the polymer to flow to form a pre-consolidated mat; Cool the mat. The aqueous slurry may be substantially free of other constituents.

The fiber content in the composites of the present invention is from about 10% to about 30% by weight based on the total weight of the part.

Suitable belt presses are described, for example, in U.S. Patent Nos. 3,159,526; 3,298,887; 4,369,083; 5,112,209; 5,433,145; 5,454,304; 5460764, 5,520, 530; 5,546,857; 5,555, 799; 5,592,874; 5759927; 5,895,546, each of which is incorporated herein by reference in its entirety. A suitable belt press, in particular an isobaric double belt press, is manufactured by Held Technologie GmbH of Germany. A manufacturer of double belt systems useful for fiber reinforced thermoplastics is Berndorf Band GmbH of Austria.

Suitable platen presses are well known, for example, in U.S. Patent Nos. 5,775,214, 5,253,571, 5,323,696 and 5,333,541, each of which is incorporated herein by reference in its entirety. Manufacturers of suitable presses include Maschinenfabrik Herbert Meyer GmbH of Germany (vertical presses or laminating presses, for example pressures up to 18,143.6 kg (20 tons) and pressures up to 400 ° C (673K) Model APV, Fusing Press AHV-Bm or AHV-S with a heating plate.

Suitable methods of applying the alternating steps of compression and heating are known, for example, from U.S. Patent No. 6,287,410, which is incorporated herein by reference in its entirety.

Suitable methods of applying heat include contacting the mat or composite article with a hot surface (e.g., conduction); Using hot gas jets (e.g., convection); And using radiation (e.g., infrared or microwave radiation).

Methods of densification are well known, for example, in U.S. Patent No. 6,032,446, which is incorporated herein by reference in its entirety.

Consolidation can be performed under the same conditions as densification. In addition, either heating to a temperature above the softening temperature or heating to a temperature below the softening temperature, or various combinations as known in the art, can be optionally performed as defined herein during consolidation . Therefore, it is possible to produce a composite article of density Dc comprising a polymer and a fiber, the method comprising providing a first mat. The first mat may be a material composed of thin mats. In any case, the mat comprises "1 to 91 weight% fiber" and "9 to 99 weight% polymer. The first mat has a density of Dm less than Dc.

The first mat is densified by compressing at a density that is greater than 1.1 times Dm and less than 0.999 times Dc while at least a portion of the first mat is at a temperature below the softening temperature. This will provide a compressed mat. Thereafter, the compacted mat is generally heated to a temperature above the softening temperature of the polymer, while the compacted density is greater than 1.1 times Dm and less than 0.999 times Dc. This will provide a pre-compacted mat, which is then cooled, or at least partially, to a temperature below the softening temperature of the polymer to provide a consolidated mat.

A plurality of consolidated mats are then laminated in a height direction to provide a non-consolidated article. Compressing the height of the non-compacted article and generally heating to a temperature above the softening temperature of the polymer to provide a consolidated composite article. At least a portion of the consolidated composite article is cooled to a temperature below the softening temperature of the polymer.

Heating the stack above the melting temperature of the polymer and then applying sufficient pressure perpendicular to the plane of the mat without restraining the mat in the plane direction to cause the fluoropolymer to flow, A method of pre-consolidating the stack by forming a pre-consolidated sheet to produce a composite article having an orientation is disclosed herein.

The composite article may be used in a chuck, for example, a spin chuck used in a coater chamber to hold a wafer, or a CMP chuck for holding a wafer during chemical mechanical polishing (CMP) or polishing a pad. A chuck that rotates about its z axis at high rotational speeds is particularly preferred because the strength of the composite in the xy plane allows for larger diameters or larger rotational speeds to be used for larger chucks or larger wafers or faster processing Or more robust processing. It is also desirable for the chuck to withstand deformation, thereby fixing the wafer in a flat position during precision processing. Cleanliness of composites (e.g., low metal content, low or slow outflow of metals or ions) is also considered important in semiconductor manufacturing articles, including spinning, rinsing and drying modules and chucks. Composites are important as support structures for semiconductor wafers, e.g., such support structures are also known as wafer chucks, susceptors, or wafer pedestals. Semiconductor manufacturing articles are described, for example, in U.S. Patent Nos. 7357842; 20090033898; 5451784; 5824177; 5803968; And 6520843, each of which is incorporated herein by reference in its entirety.

Composite articles are useful for compressor valves such as those disclosed in U.S. Patent No. 7,011,111, which is incorporated herein by reference in its entirety.

The present invention relates to a simplified manufacturing process; A robust / robust or reproducible manufacturing process capable of producing robust / robust or reproducible products; Producing an article of increased density; Articles of increased density; In the case of a process comprising a solvent or water, producing a product having less metal, metallic, ionic or related impurities; A process for using fibers to maintain fiber length; Producing a product having uniform properties across the useful volume; (E.g., tensile strength, compressive strength, or elongation at break) of uniform or superior (or uniform or superior in one direction, or uniform or superior in two orthogonal directions) regardless of the direction of measurement (Including, but not limited to) at least one or a combination thereof.

The composite article of the present invention can be used in known applications, for example, equipment for semiconductor manufacturing, aircraft parts, automobile parts, gaskets, seals and the like. The article of the present invention may be a spin disk.

Example

Methods of making materials and articles similar to those described below are described in U.S. Patent No. 5,470,409 to Dickin et al., Entitled " Method of Making Fluoropolymer Composites, "filed November 28, 1995, U.S. Patent No. 5,232,975 issued to Dickin on Aug. 3, 1993, entitled " Pre-Consolidation Method for the Production of Fluoropolymer Composites ", filed on June 27, 1995, entitled " U.S. Patent No. 5,427,731 to Chesna et al., And U.S. Patent No. 4,163,742 to Mansur, issued Aug. 7, 1979, entitled " Products and Methods Manufactured from Tetrafluoroethylene Polymers and Graphite Fibers, , All of which are incorporated herein by reference in their entirety.

In the following examples, Teflon.RTM. PFA is available from EI du Pont de Nemours and Company of Wilmington, Del. children. Is a registered trademark of EI du Pont de Nemours and Company and is available from EI du Pont de Nemours and Company and contains about 99 mole% of tetrafluoroethylene and about 1 mole% of perfluoro (propyl vinyl ether) Polymers.

The carbon fiber CF1 used was polyacrylonitrile-based, about 6.0 mm in length, about 5 to 7 micrometers in diameter, about 200 g / L in bulk density, and about 4 weight% , A carbon density of about 1.8 g / cm < 3 > according to ASTM D1505, a tensile strength according to ASTM D4018 of greater than 3450 MPa (greater than about 500 ksi) and a tensile modulus of greater than about 218 ㎬ (31.6 Msi). Elemental analysis of the fiber for the metal content of nanomole units per gram of fiber resulted in about 170 000 for sodium, 770 for potassium, 180 for calcium, and 22 for aluminum.

Similar fiber CF2 had lower metal content. Elemental analysis of the fiber for the metal content of nanomole units per gram of fiber showed a result of about 830 for sodium, 510 for potassium, less than 10 for calcium, and about 3 for aluminum. The tensile strength was greater than 3.45 ((greater than 500 ksi), the tensile modulus was greater than 207 ((greater than 30 Msi), and the fiber appeared to be somewhat stronger than CF1. The sizing level was 3.8 wt%, and the sizing was water-soluble.

The fiber CF3, which has similar physical properties to CF2, also had a metal content similar to CF2, but essentially no sizing.

PFAP1 (tetrafluoroethylene-perfluoro (propyl vinyl ether) copolymer, CAS 26655-00-5), a type of Teflon (registered trademark) PFA pellets, has a melting point of about 305 DEG C and a flow rate of 14 g / 10 min), tensile yield strength is about 13.8 MPa, and tensile strength according to ASTM D3307 is about 25 MPa at 25 DEG C, 12 MPa at 250 DEG C, and specific gravity about 2.15 g / mL.

The PFA flakes from PFAP1 (PFAF1) were prepared using a disc mill of the type manufactured by Andritz Sprout (Muncie, Pa.) As taught in Dickins US 5506052.

Wet mats Mw1 were prepared from 20 wt.% CF1 and 80 wt.% PFAF1 according to the method of U.S. Patent No. 5506052.

The drying mat Md1 made from Mw1 (prior to noteworthy compression of Mw1) is 16.75 inches wide, 18 inches long, 45 inches (0.12 lb / ft2) ² ).

The cohesive mat Mc1 made from Md1 (prior to notable compression of Md1) is approximately 2.4 mm thick, or approximately 0.095 inches thick, and has approximately the same basis weight.

Pre-consolidated articles CAp1-24 were prepared from the cut portion of coherent mat type Mc1 on a platen press. A square of about 41.9 cm (16.5 inches) was cut and the original longitudinal direction was indicated. About 24 squares are stacked vertically one above the other in the longitudinal direction (in the case of an upper or lower mat) or two nearest neighbor mats (in the case of an inner mat, respectively) Stack. The stack, which is essentially ambient temperature, is placed in a temperature controlled platen press and the thickness (z) at a pressure less than 90 psi (4310 Pa) without restraint by any pressure added in the length and width (x and y) The stack was heated to 310 ° C (583K, 590 ° F) across the stack while compressing the stack to the minimum. Then, while the heating was stopped and the cooling started, the fully heated stack was further compressed along the thickness direction. Thus, the stack was consolidated to a thickness of about 0.72 cm (0.285 inch) and the temperature was reduced to less than 290 ° C (563K, 554 ° F) throughout the article. The temperature of the stack and the pressure thereupon were then reduced to ambient conditions to obtain supplies CA1-24.

By replacing carbon fiber CF1 with carbon fiber CF2 and carbon fiber CF3, respectively, products CA2-24 and supplies CA3-24 were prepared as in CA1-24. The wet mat Mw3 containing CF3 (without sizing) was significantly different in processability and appearance compared to Mw2 containing Mw1 and CF2. The composite material prepared from the sizing treated carbon fiber CF2 exhibited excellent tensile strength and appearance.

A pre-compacted mat was prepared using a heatable belt press HBP1 or HPB2. HBP1 was a continuous dual belt press with a working width of about 76.2 cm (30 inches) and a working length of about 305 cm (10 feet). The work height of the constant gap was adjustable. The belt press temperature was adjustable in a number of zones.

In the BP1 run, the inlet zone of HBP1 was set to 500 ° F, the internal transfer zone was set to 371 ° C (700 ° F), and the latter cooling zone within the working length was set to about 0 ° C (32 ° F) Lt; RTI ID = 0.0 > 100 C < / RTI > and cooled by water exiting the final cooling zone. The gap between the two belts was set at about 0.24 cm (0.028 inches) when measuring the thickness after discharge by the length of the solder passing through the press. Both belts were coated with release formulations. A single sheet of mat having a height of about 0.095 inches was passed through the press to continuously produce a pre-consolidated mat having a height of about 0.038 inches (0.038 inches). The mat was fed to the belt press at 30.5 cm / min (12 inches / min). In BP2 operation, the feed rate of the mat was increased to 38.1 cm / min (15 inches / min).

In BP3 operation, the three mats were fed continuously and simultaneously to the belt press, with their lengths aligned in parallel. The gap between the two belts was about 0.21 cm (0.084 inches) and the pre-consolidated mat height was about 0.11 cm (0.045 inches). The feed rate was 30.5 cm / min (12 inches / min).

Similarly, in BP4, five mats were fed to the belt press continuously and simultaneously, with their lengths arranged in parallel. The gap between the two belts was about 0.25 cm (0.10 inches) and the pre-consolidated mat height was about 0.19 cm (0.075 inches). The feed rate was 30.5 cm / min (12 inches / min).

The pre-compacted mats from each belt press process (BP1 to BP4, etc.) are individually cut into sections and assembled into a stack orthogonal to each other as in a platen-press-manufactured material, and finally compressed Respectively.

The final compaction of the stack of pre-compacted mats was performed to achieve a final product having a height of about 16.5 cm (6.5 inches).

The pre-compacted mat prepared on a platen press at a density of 1.85 g / ml expanded during heating to above 300 ° C while suppressing [703 kg (1/2 cm 2) to 80 cm 2 (16 square inches) 1.4 g / ml. The pre-consolidated mat prepared on a constant gap belt press had a density of about 1.4 g / ml and did not undergo significant expansion during heating to 300 DEG C while maintaining the same pressure. The final densification was greater in the case of a resolidified mat made on a belt press of constant gap under the same conditions of exposure pressure and temperature profile in the article press.

The composite article may have a thermal expansion coefficient in the xy direction of about 10 ppm / K; The thermal expansion coefficient in the Z direction may be larger or smaller in the xy direction.

Unless otherwise stated, all parts are on a mass basis.

Claims (1)

(a) from about 70% to about 90% by weight of a thermoplastic polymer;
(b) from about 10 to about 30 weight percent of chopped carbon fibers;
(c) 0.001 to about 10% sizing agent selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol, copolyvinyl alcohol, copolyvinyl acetate, copolyvinyl alcohol-acetate and sodium carboxymethyl cellulose. (a), (b) and (c) further comprising (d) less than 2000 nanomoles per gram of combined sodium, potassium, calcium and aluminum, Is based on the total weight of the part.

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