The present invention relates generally to a method for patterned depositions of a material onto a substrate for marking purposes. More particularly, the present invention relates to a system for applying information to a fluoropolymer substrate involving engraving a pattern in the fluoropolymer substrate with a laser or other high precision engraving means, applying a fluoropolymer-compatible character definition media (ink) within the etched pattern, and curing or bonding the character definition media to the etched pattern to provide a simple and durable marking on the fluoropolymer substrate which can withstand exposure to harsh chemicals and high temperatures. π. Discussion of the Prior Art

In the field of electronics, manufacturers have for years employed the use of fluoropolymer trays or carriers for transporting semiconductor wafers or memory disks. Fluoropolymer materials are attractive for this use due to their low dielectric constant, low dissipation factors, high thermal stability, and high chemical resistance. As such, the fluoropolymer carriers provide a static-free, safe environment for the sensitive electronics during transportation between the various processing locations within a single manufacturing facility and/or between different manufacturing facilities. Moreover, the fluoropolymer carriers are capable of withstanding exposure to the high temperatures and harsh chemicals found in electronics manufacturing processes. A drawback exists, however, in that the chemical and physical inertness of fluoropolymers, such as perflouroalkoxyethylene (PFA), makes it difficult to deposit adhesives, coatings, and the like onto the carriers. The deposition of material onto such fluoropolymer carriers is desirable from the standpoint of conveying important information, such as bar codes for tracking the progress of each carrier throughout the various manufacturing and processing operations, as well as trademarks and related information to indicate the source of the particular goods.

Various approaches have been developed through the years to combat the inertness of fluoropolymer materials in the hope of successfully applying marking indicia thereto. One such technique is disclosed in U.S. Patent No. 4,833,306 to Milbrett,

wherein marking is accomplished by molding an electronics carrier to include a recessed area sized to receive a bar code label. An appropriately sized bar code label is created and then placed within the recessed area in the item to be marked. An optically transparent cover is then used to encapsulate the separate bar code label within the recessed area. Through this encapsulation, the bar code label is protected from attack by the various harsh chemicals used in the processing of semiconductor wafers or memory disks. Moreover, the optically transparent cover allows the bar code label to be read by various sensing devices such that the progress of the carrier may be monitored during the manufacturing processes. A significant drawback exists with this marking system, however, in that it is costly and relatively complicated to manufacture. The cost of materials used to make the trays is increased due to the need for a separate bar code label and an optically transparent cover, above and beyond the carrier itself. In similar fashion, the cost associated with manufacturing the trays is increased due to the special tooling required to effectuate the molding of the recessed area, as well as the labor required to insert the bar code label into the recessed area and to hermetically seal the optically transparent cover over the recessed area.

Another approach to marking a fluoropolymer article is disclosed in U.S. Patent No. 5,227,099 issued to Kamon et al. More specifically, the surface of a thermoplastic synthetic resin is modified by irradiating the molded article with a laser to expand any moisture and/or air contained in the resin and thereby create raised foamed regions. The laser can be directed easily about the surface of the molded article to achieve the desired printing in the form of the raised foam regions. While this technique is advantageous in that it is relatively simple and straightforward, a substantial drawback exists in that the raised foam portions are the same color as the rest of the molded article. More specifically, having unity of color between the printing and the molded article is a disadvantage because it is difficult for a scanning device to read a marking such as a bar code when the marking is the same color and the article. As such, this method does not lend itself to the field of manufacturing electronics, where scanning systems are used to track the progress of the fluoropolymer carriers within a particular manufacturing facility or between various manufacturing facilities. Moreover, the clear print attainable through this method does not lend itself to printing logos or trademarks on the fluoropolymer

articles in that such marks are incapable of standing out so as to be readily visible by consumers

Another popular approach to combating the inertness of fluoropolymer materials involves modifying the surface of the fluoropolymer article to more readily accept the application of adhesives, paint, and the like. One particular technique focuses on adding various materials to the fluoropolymer during the molding of the article and thereafter treating portions of the surface of the molded article to improve the adhesion characteristics and wetting properties thereof In this regard, U S. Patent No 5,320,789 issued to Nishii et al discloses a method for modifying the surface of a fluorine resin which entails adding a heat resistant light-absorbing compound to the resin during the molding of the resin into a particular article The molded article, comprising a combination of fluorine resin and the heat resistant light absorbing compound, is then etched with a laser to create selected portions having improved adhesion characteristics and improved wetting properties on the surface of the molded article As indicated above, these etched areas are then more capable of accepting of adhesives for the application of labels and various paints for marking purposes U S Patent No 5,470,617, also issued to Nishii et al , discloses a similar arrangement, wherein an ultra-violet absorbing compound and a fluorosurfactant are combined with the fluorine resin during the molding of an article The molded article is then irradiated with an ultra-violet laser to again create etched areas having improved adhesion characteristics and wetting properties In similar fashion, U.S

Patent No 5,273,789 issued to Shinonaga et al. entails adding various quantities of (1) propylene, (2) ethylene-propylene copolymer rubber, and (3) ethylene-acrylic or ethylene- methacrylic acid copolymer to a polypropylene resin during the molding of an article As with the method of the '617 patent, the molded article is thereafter irradiated with ultra- violet light to create etched portions having improved adhesion and wetting characteristics Each of the above techniques share a similar drawback in that it is costly, in terms of both material and labor, to meter the various materials into the resin during the molding of the articles Moreover, a drawback exists with the use of ultra-violet irradiation in that, when administered improperly, it may result in unsatisfactory adhesive and wetting properties and/or deterioration of the etched surface

Another technique involves laser etching the fluoropolymer article while the article

is exposed to, or in contact with, another material. U.S. Patent No. 5,362,525 issued to Nishii et al. discloses one such method, wherein the surface of a fluorine resin is modified for improved adhesion and wetting characteristics by irradiating the resin with an ultra¬ violet laser in the presence of an inorganic silicon compound. To be more specific, the inorganic silicon compound may take the form of a fine powder which is directly spread on the surface of the fluorine resin, or an aqueous solution which is in direct contact with the surface of the fluorine resin. In either case, the inorganic silicon compound must first be in contact with the surface of the fluorine resin prior to ultra-violet irradiation. U.S. Patent No. 5,419,968 issued to Okada et al. discloses a similar method. In the Okada reference, however, the surface of the fluororesin is hydrophilized by irradiating a portion of the molding with an ultra-violet laser while the molding is in contact with a gas-treated water solution. A disadvantage exists with these methods, however, in that a substantial amount of time and resources must be expended to ensure that the various solutions or materials are evenly distributed about the surface of the molded articles, and in the appropriate proportions.

A still further technique for modifying the surface of a polymeric material is disclosed in U.S. Patent No. 5,066,565 issued to Martinez et al This reference discloses a photolithographic method for treating a polymeric article which involves exposing portions of the surface of the article to ionizing radiation and then subjecting the surface to chemical etching. The ionizing radiation treatment serves to minimize the effect of the chemical etching treatment. As such, the irradiated portions of the article are effectively masked during the chemical etching so as to remain unmodified. Various drawbacks exist with this method, however, including the well known health risks associated with using ionizing radiation. This method is also generally undesirable due to the increased costs associated with ionizing radiation, both in terms of the cost of the radiation equipment and the cost involved in ensuring for the safety of workers during such radiation procedures.

Yet another method for modifying the surface of a fluoropolyer substrate is illustrated in U.S. Patent No. 5,380,474 issued to Rye et al. More specifically, a method is described for patterned dispositions of a material onto a fluoropolymer substrate, wherein the surface of the substrate undergoes a chemical etching treatment to provide

a first etched layer Selected portions of the first etched surface are then ablated via a laser to produce a smooth pattern on a plane lower than the plane of the first etched surface Through this action, improved adhesion characteristics and wetting properties are formed on the first etched surface, whereas the smooth pattern formed through the ablation process has the poor adhesive and wetting properties that are characteristic of untreated fluoropolymer articles The drawback of this method stems from the need to perform two separate and distinct operations before the surface of the fluoropolymer article is conditioned to readily accept adhesives and other surface coatings Once again, this method requires the first step of etching the entire surface of the polymeric article and the second step of performing an ablation process to remove portions of the previously etched surface before the surface of the article is adequately modified This seems wasteful in that a significant amount of time and precision are required to perform the two separate and distinct steps Additionally, this seems wasteful in that it is duplicative to subject the original surface of the molded article to two conditioning steps to reach the final point where the article is capable of more readily accepting adhesives and/or various surface coatings

A need therefore exists for a marking system for use in applying information to a fluoropolymer substrate which is inexpensive and easy to implement, requiring no custom molding nor the use of separate labels and hermetically sealed recessed areas A further need exists for a marking system which is readily visible such that, as a bar code or the like, the marking may be easily detected by scanning systems and, as a trademark or logo, the marking will be readily apparent to members of the consuming public A need also extends to a marking system which does not require any special treatment or mixing procedures during the molding of the fluoropolymer article such that previously existing molded articles may be readily marked regardless of when the article was molded A further need exists for a marking system which does not require the application of supplemental solutions or substances to the molded article during laser etching treatments A need also exists for a marking system that is safe to effectuate and which does not expose workers to health risks such as those associated with ionizing radiation Lastly, and importantly, a need exists for a method of marking fluoropolymer articles which involves a minimal number of conditioning steps before the article is capable of readily

accepting adhesives and/or surface coatings.

SUMMARY OF THE INVENTION

It is accordingly a principal object of the present invention to provide a marking system for applying information to a fluoropolymer substrate which is economical and easy to implement, requiring no custom molding nor the use of separate labels and hermetically sealed recessed areas.

It is a further object of the present invention to provide a marking system for applying information to a fluoropolymer substrate which is capable of withstanding high temperatures and harsh chemicals found in electronics manufacturing processes and operations.

A still further object of the present invention is to provide a marking system that is highly visible such that, as a bar code or the like, the marking may be easily detected by scanning systems and, as a trademark or logo, the marking will be readily apparent to members of the consuming public. It is another object of the present invention to provide a marking system which does not require any special treatment or mixing procedures during the molding of the fluoropolymer article such that previously existing molded articles may be readily marked regardless of when the article was molded.

It is yet another object of the present invention to provide a marking system which does not require the application of supplemental solutions or substances to the molded article during laser etching treatments.

It is still another object of the present invention to provide a method of marking fluoropolymer articles which involves a minimal number of conditioning steps before the article is capable of readily accepting adhesives and/or surface coatings. In accordance with the present invention, the foregoing objects and advantages are achieved by providing a method for applying information to a fluoropolymer substrate, comprising the steps of: (a) engraving the fluoropolymer substrate to define at least one engraved recess area extending a predetermined depth below a surface of the fluoropolymer substrate; (b) introducing a quantity of character definition media into the at least one recess area; and (c) curing the character definition media within the at least one recess area to form a bond between the character definition media the said at least one

recess area

In accordance with another broad aspect of the present invention, the aforementioned objects are attained by providing a system for marking a fluoropolymer substrate, comprising the steps of (a) engraving the fluoropolymer substrate to form at least one engraved portion therein, and (b) providing a quantity of fluoropolymer- compatible character definition media within the at least one engraved portion

In yet another broad aspect of the present mvention, a method is disclosed for marking a fluoropolymer earner for use in transporting electronic components, comprising the steps of (a) engraving at least one mark on a surface of the fluoropolymer earner wherein the at least one mark comprises at least one of an alphanumeπc character, a bar code, and a symbol, and (b) curing a quantity of fluoropolymer-compatible character definition media within the at least one mark

The foregoing features and advantages of the present invention will be readily apparent to those skilled in the art from a review of the following detailed description of the preferred embodiment in conjunction with the accompanying drawings and claims

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view illustrating a fluoropolymer carrier 10 for use in transporting electronic components equipped with a bar code marking 20 in accordance with the present mvention, FIGURE 2A is a cross sectional view of a fluoropolymer substrate 30 with a plurality of engraved portions 40 formed therein, and

FIGURE 2B is a cross sectional view of the fluoropolymer substrate 30 with each of the plurality of engraved portions 40 filled with a fluoropolymer-compatible character definition media 50 to accomplish the desired fluoropolymer marking system of the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring initially to FIG 1 , shown in perspective is a fluoropolymer carrying tray 10 for use in transporting semiconductor wafers or memory disks capable of being marked in accordance with the fluoropolymer marking system of the present invention Fluoropolymer resins are ideal for use in this regard due to their low dielectric constant, low dissipation factors, high thermal stability, and high chemical resistance, thereby

providing a static-free, safe environment for sensitive electronics during transportation between the various processing locations within a single manufacturing facility and/or between different manufacturing facilities. Fluoropolymer resins for use in the marking system of the present invention may include, but are not limited to, the following: copolymer of tetrafluoroethylene with perfluoroalkoxyethylene (PFA), copolymer of tetrafluoroethylene with hexafluoroproylene (FEP), polytetrafluoroethylene (PTFE), teφolymer of tetrafluoroethylene with hexafluoropropylene and perfluoroalkoxyethylene (EPE), copolymer of tetrafluoroethylene with ethylene (ETFE), polychlorotrifluoroethylene (PCTFE), copolymer of trifluorochloroethylene with ethylene (ECTFE), polyvinylidene fluoride (P VDF), and polyvinyl fluoride (PVF) In a preferred embodiment of the present invention, the fluoropolymer resin comprises PFA However, it is to be understood that any of the aforementioned fluoropolymer resins will perform equally well in the marking system of the present invention and that such fluoropolymer articles may be molded from a mixture of any number of said fluoropolymer resins. As previously noted, a drawback exists with the use of fluoropolymer resins in that the chemical and physical inertness of fluoropolymers makes it difficult to deposit adhesives, coatings, and the like onto the surface of articles molded therefrom With the present invention, fluoropolymer articles such as the carrying tray 10 are capable of being marked with indicia without the use of external labels or sophisticated etching techniques which require special additives within the fluoropolymer resin and/or etching in the presence of various compositions. In the embodiment shown, this marking takes the form of a bar code comprising a plurality of vertically oriented lines, indicated generally at reference numeral 20 As is well known in the art, bar codes such as the bar code 20 are used in conjunction with optical scanning systems so as to automate and expedite data entry to facilitate item identification, inventory tracking, or the like, thereby replacing the tedious and repetitious task of manual data entry In the field of manufacturing or assembling sensitive electronics, this may be accomplished by positioning scanning devices at various points throughout manufacturing or assembly process to read and interpret the bar code 20 located on the surface of the carrying tray 10 Through this arrangement, each and every carrying tray 10 can be tracked and documented during transportation for, among other reasons, maximizing the efficiency of said transfer operations

Referring now to FIGS. 2A and 2B, the fluoropolymer marking system of the present invention will now be explained with reference to a fluoropolymer substrate 30 formed from any number of fluoropolymer resins. In its broadest sense, the fluoropolymer marking system of the present invention includes the steps of: (1) engraving a fluoropolymer substrate to form at least one engraved portion therein; and (2) providing a quantity of fluoropolymer-compatible character definition media within the at least one engraved portion. During the first step, selected portions of the surface of the fluoropolymer substrate 30 are engraved to form at least one engraved or recessed portion therein. For illustration purposes, a plurality of engraved portions 40 are shown in FIGS. 2A and 2B representative of the engraving operation required to produce the bar code 20 in FIG. 1. However, it is to be understood that the engraved portions 40 of present invention may be patterned to formed any number or combination of alphanumeric characters, bar code, and symbols including, but not limited to, trademarks and similar logos. This step of engraving can be accomplished via any number of etching or engraving techniques. In a preferred embodiment of the present invention, this engraving step is performed through the use of a laser which is capable of selectively and accurately removing portions from the surface of the fluoropolymer substrate 30. For example, a carbon dioxide laser is particularly suitable for engraving various indicia in articles molded from PFA fluoropolymer resin. One of several commercially available carbon dioxide lasers may be employed in this regard, including but not limited to the SUMMIT™ laser engraver produced by the Epilog Coφoration. Through the controlled application of the laser to the surface of the fluoropolymer substrate 30, each engraved portion 40 comprises a highly resolved marking which extends a predetermined depth D below the surface of the fluoropolymer substrate 30.

The second step in the marking system of the present invention involves the use of a fluoropolymer-compatible character definition media. More specifically, with reference to FIG. 2B, a quantity of fluoropolymer-compatible character definition media 50 is introduced into the engraved portions 40 of FIG. 2 A. If required, the character definition media 50 may be thereafter cured in any number of appropriate fashions to ensure for the formation of a strong bond between the character definition media 50 and

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the engraved portions 40. In a preferred embodiment of the present invention, the character definition media 50 may comprise any number of commercially available inks capable of being thermally or chemically bondable to fluoropolymer resins, including but not limited to Gem Type FEP TEFLON® Black 6020 black ink produced by Gem Gravure Company, Inc. This particular fluoropolymer-compatible character definition media comprises approximately 59% MIBK, 25% MEK, 6% diacotone alcohol, 5% butyl carbitol, and 5% butyl alcohol. Character definition media solutions having similar compositions are likewise within the ambit of the present invention and restriction to the above-identified percentages or manufacturer is not to be inferred. For instance, it is conceivable to produce a suitable character definition media comprising MIBK in a concentration ranging between 50 and 70 percent, MEK in a concentration ranging between 20 and 30 percent, diacotone alcohol in a concentration ranging between 1 and 10 percent, butyl carbitol in a concentration ranging between 1 and 10 percent, and butyl alcohol in a concentration ranging between 1 and 10 percent Notwithstanding the above- identified variations in the composition of the character definition media, the Gem Type FEP TEFLON ® Back 6020 black ink was found to be particularly useful in providing highly resolved bar code markings on the surface of carrying trays, such as that shown in FIG. 1, which are molded from PFA and/or FEP fluoropolymer resins.

The actual introduction of the character definition media 50 within the engraved portions 40 may be performed in any number of suitable fashions For example, when operating with a computer controlled engraving system, it is possible to calculate or otherwise determine the volume of each engraved portion 40 during the engraving process and thereafter use this information to inject an appropriate amount of character definition media 50 into each respective engraved portion 40 via automated injection techniques Alternatively, the character definition media 50 may be soaked up within a cotton swab or other similarly absorbent material and dabbed over each engraved portion 40 to fill the entire depth D of each engraved portion 40 with the character definition media 50. In this technique, it may be useful or necessary to pass a tissue or other absorbent material over the surface of the fluoropolymer substrate 30 to remove any of the character definition media 50 which may extend onto the surface of the fluoropolymer substrate 30 following the dabbing of the cotton swab over each engraved portion 40.

In the preferred embodiment of the present invention shown in FIG. 1 , the fluoropolymer marking system of the present invention provides a highly resolved bar code 20 comprising a plurality of vertically oriented engraved portions disposed in side- by-side relation along a front surface of the fluoropolymer carrying tray 10. To accomplish this marking, each vertically oriented engraved portion of the bar code 20 is formed within the surface of the carrying tray 10 using a carbon dioxide laser engraver. Preferably, each engraved portion of the bar code 20 should have a predetermined depth D of at least 2 one thousands of an inch to ensure that the character definition media will not be inadvertently smudged or removed from within each engraved portion during the process of cleaning up any excess character definition media from the surface of the fluoropolymer substrate prior to curing the character definition media within the engraved portions. Depending upon the type of character definition media employed, the curing process may entail a simple drying process, thermal or otherwise, a chemical bonding process, and/or a physical bonding process or any combination thereof. In light of the foregoing, the present invention solves the various drawbacks found in the prior art. To be more specific, the present invention provides a marking system for applying information to a fluoropolymer substrate which is economical, easy to implement, and requires no custom molding nor the use of separate labels and hermetically sealed recessed areas. The marking system of the present invention is capable of withstanding high temperatures and harsh chemicals found in electronics manufacturing processes and operations and further produces highly visible markings that may be identified easily by scanning systems and/or members of the consuming public. The present invention also provides a marking system which does not require any special treatment or mixing procedures during the molding of the fluoropolymer article such that previously existing molded articles may be readily marked regardless of when the article was molded.

Moreover, the marking system of the present invention does not require the application of supplemental solutions or substances to the molded article during laser etching treatments. The present invention also provides a method of marking fluoropolymer articles which involves a rnύiimal number of conditioning steps before the article is capable of readily accepting adhesives and/or surface coatings.

This invention has been described herein in considerable detail in order to comply

with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment details and operating procedures, can be accomplished without departing from the scope of the invention itself. What is claimed is: