MXPA99005039A - Subject carrier compue - Google Patents

Abstract

A pellet carrier is formed of at least two different molten processable plastic materials in which two plastics materials strategically placed for optimum performance and have a thermophysical bond created during an overmold process. The invention includes carriers made of different plastics processable by casting and includes the process for manufacturing such carriers. In a preferred embodiment an H-shaped bar pellet carrier will have a first molded structural portion of polycarbonate in a first mold cavity and then the molded portion of polycarbonate placed therein. a second mold cavity and the polyetheretherketone being injection molded to form pellet contact portions in the H-shaped bar carrier. The temperature process and mold temperatures are controlled to provide optimum bonding between the different materials. In this way, an integral pad carrier of the composite materials was formed. An additional embodiment uses components such as shelves or sidewall inserts to hold molded pads of two different plastics and the components are mounted within an enclosed disk such as a transport module.

Description

COMPOSITE SUBSTRATE CARRIER DESCRIPTION OF THE INVENTION This invention relates to devices for confining memory disks, silicon wafers, and the like for transporting, storing, processing. More particularly, the invention relates to a composite tablet or carrier disk. Certain carriers are used to transport and store batches of silicon wafer files or magnetic disks before, during and after the processing of the disks or pads. The pads are processed inside the integrated circuits and the disks are processed inside the magnetic computer storage disks. When the tablets are used herein, they refer to silicon wafers, magnetic substrates, and the like. The processing of chip discs within integrated circuit chips sometimes involves several stages when the discs are processed, stored and transported repeatedly. Due to the delicate nature of the discs and their extreme value, it is vital that they are properly protected through this process. One purpose of a pill carrier is to provide this protection. Additionally, since the processing of tablet discs is generally automated, this is necessary for the discs that will be placed correctly in relation to the processing equipment for the elimination and automatic insertion of the pellets. A second purpose of a pill carrier is to keep the pill discs secured during transport. The carriers are generally configured to axially align the pads or discs in the slots, and to support the pads or discs by or near their peripheral ridges. The pellets or discs are conventionally removable from the carriers in a radially ascending or lateral direction. The carriers may have complementary elements for covers, bottom covers, or enclosures for enclosing the pads or discs. There are a number of material features that are useful and advantageous for tablet carriers depending on the type of carrier and the particular part of the carrier in question. During the processing of semiconductor wafers or magnetic disks, the presence of or generation of particles presents very significant contamination problems. Pollution is accepted as the single biggest cause of the loss of performance in the industrial semiconductor. As the size of the integrated circuitry has continued to be reduced, the size of the particles that can contaminate an integrated circuit becomes smaller as well, minimizing all the most critical pollutants. Pollutants in the form of particles can be generated by abrasion such as friction or scraping of the carrier with the pads or discs, with the carrier covers or enclosures, with storage shelves, with other carriers, or with the processing equipment. A more desirable characteristics of a carrier is therefore a resistance to the generation of particles by abrasion, friction or scraping of the molded plastic material. U.S. Patent No. 5,780,127 describes various characteristics of plastics that are pertinent to the proper capacity of such materials for bar carriers. Such a patent is incorporated by reference. The carrier materials should also have minimal degassing of volatile components as these can leave films that also constitute a contaminant that can damage the pads and discs. The carrier materials must have adequate dimensional stability, which is rigid, when the carrier is loaded. Dimensional stability is necessary to prevent damage to the pads or discs and to minimize movement of the pads or discs inside the carrier. The tolerances of the slots that hold the pads and discs are typically very small and any deformation of the carrier can directly damage the highly fragile pads or they can increase the abrasion and thus the generation of particle when the pads or discs are moved inwards., outside, or inside the carrier. Dimensional stability is also extremely important when the carrier is loaded in some direction, such as when the carriers are stacked during shipment or when the carriers are integrated with the processing equipment. The carrier material should also maintain its dimensional stability under elevated temperatures that can be encountered during storage or cleaning. Conventional carriers used in the semiconductor industry can develop and retain static charges. When a part of charged plastic comes into contact with an electronic device or processing equipment it can discharge into a damage phenomenon known as electrostatic discharge (ESD). Additionally, static charge carriers can attract and retain particles, particularly, aerial particles. Also the static accumulation on carriers can cause the semiconductor to process the equipment to close automatically. It is more desirable to have a carrier with static dissipation characteristics to eliminate ESD and avoid attracting particles. Trace metals are a common ingredient or residue in many potential pellet carrier materials. Metal contamination should be considered in the selection of material and methods of assembly of carriers. The contamination of the anion in the carrier materials can cause problems of contamination and corrosion. The material used in carriers must also be chemically compatible to any chemicals that may be subjected. Although the transport and storage of cell carriers are not intended for chemical use they must be resistant to cleaning solutions and commonly use solvents such as isopropyl alcohol. The processed carriers are subjected to ultrapure acids and other harsh chemicals. The visibility of the pellets inside the closed containers is highly desirable and may be required by end users. Transparent plastics suitable for such containers, such as polycarbonates, are desirable in that such plastic is low in cost although such plastics do not have desirable static dissipation characteristics, nor desirable abrasion resistance. Other important features include the cost of the carrier materials and the ease of molding the material. The carriers are typically formed from injection molded plastics such as polycarbonate (PC), styrene of acrylonitrilebutabiene (ABS), polypropylene (PP), polyethylene (PE), perfluoroalkoxy (PFA), and polyetherreeketone (PEEK).

Fillers that have to be added to injection molded plastics by static dissipation include carbon or fiber powder, metal fiber, metal covered with graphite, and organic additives (based on amine). A common conventional pill carrier used for transport and storage is a simple molded part which generally comprises a front end having an H-shaped bar interface portion, a back end having a panel and side walls having slots and Conversion portions or lower curves following the curvature of the pellets, and with an open top and open bottom. H-shaped bar holders will often be reused several times and then downloaded. Among the uses of the carriers will typically be washed in hot pads and / or other chemicals and then dried with hot air. It is a valuable feature to have a carrier that maintains its shape when subjected to elevated temperatures associated with cleaning, drying, transportation and processing of carriers. Another conventional carrier is a box configured to maintain an H-shaped bar carrier. Such boxes are commonly known as work in process boxes (WIP). Another conventional carrier is a standardized mechanical interface sheath (SMIF) that is comprised of a box that encloses in sealed form an H-shaped bar carrier, which mechanically interconnects with the equipment in process. The SMIF pods typically have a bottom open hatch to access the H-shaped bar carrier with pellets. It is also known that the boxes have front open gates to access the H-shaped bar carrier. Another known carrier is a transport module that is a box lock with a front open gate and internal shelves that support the pads better than a H-shaped bar carrier separated. It must be recognized that the ideal material for a part of a carrier is typically not the ideal material for a different part of the same carrier. For example, PEEK is a material that has ideal abrasion resistance, ideal characteristics for portions of contact pad, although it is difficult to mold and is, in relation to other plastics, very expensive. In that way, PEEK can not be as good at choosing as other plastics, such as polycarbonate, structural portions. The only examples of what different materials are known to have been used for different portions of disc carriers is by separately molding the different portions by assembling them into a carrier. Such assemblies have the disadvantage of surface contacting of different components that can create areas of particle trapping or contaminants that are difficult to clean. Additionally, the assembly process can generate particles. In addition, the molding of different parts of components and the same assembly into a carrier involves work and thus cost. A pellet carrier is formed of at least two different melt-processable plastic materials in which the two plastics materials are strategically placed for optimum operation and have a thermophysical bond created during the overmolding process. The invention includes carriers made of different melt-processable plastic materials and include the process for making the carriers. In a preferred embodiment, H-shaped bar pellet carriers will have a first molded structural portion of polycarbonate in a first mold cavity and then have the polycarbonate mold portion placed in a second mold cavity and the polyetheretherketone will be molded by injection to form the pellet contact portions in the H-shaped bar carrier. Processed temperatures and molding temperatures are controlled to provide optimum links between the different materials. In this way, an integral tablet carrier of composite materials is formed. An additional embodiment uses components such as shelves or side wall inserts to hold the molded pads of two different plastics and the components are assembled with a disk enclosure such as a transport module. An advantage and feature of the invention is that a carrier can be formed to provide optimum performance characteristics to the material and minimum work costs. A further feature and advantage of the particular preferred embodiments of the invention is that there is no assembly of the component parts while maintaining the advantages of using the combination of two materials. An additional feature and object of the particular preferred nodes of the invention is that a substantially integral carrier or component is created by the two portions of plastics that are molded together. Another advantage and characteristic of the invention is that the union between two different materials is to eliminate the potential entrapment of contaminants or other chemicals. Another object and feature of the invention is that the process can eliminate packaging conditioning of tablet carriers that would otherwise be required, such as annealing.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an H-shaped bar pellet carrier according to the invention. Figure 2 is a figure showing the overmolded portion of the carrier of Figure 1. Figure 3 is a perspective view of a prior work-in-process (WIP) technique. Figure 4 is a perspective view of an IP box and an H-shaped bar carrier according to the invention. Figure 5 is a side elevational view of an IP box according to the invention. Figure 6 is a perspective view of a prior art of the disc magazine. Figure 7 is the body of a disc magazine according to the invention. Figure 8 is a prior art view of transport nodes. Figure 9 is an exploded view of a transport module similar to that shown in Figure 8 according to the invention. Figure 10 is a perspective view of a composite tablet carrier. Figure 11 is an exploded view of the pellet carrier of Figure 10.

Figure 12 is a perspective view of an improved carrier process according to the invention. Figure 13 is a schematic illustration of the methodology of the invention. With reference to Figure 1 an H-shaped bar pellet carrier is broken off and is generally indicated with the number 20. This carrier has, as in conventional H-shaped bar holders, a front part 22, a part rear 23, side walls 24, 26, slots for receiving pads 28, an upper opening 30, and an interface portion machine configured as an H-shaped bar 32. Each of the slots is defined by a pair of pads coupled to the teeth 34. The traditional H-shaped bar pickup carrier has, in addition to the H-bar machine interface, a 38 bottom-bottom machine interface that will have - typically four feet with a contact at the corners 40. Additionally, an automatic raising handle 42 and automatic tabs 44 also function as interconnections to the machine. The composite H-shaped bar carrier generally has a first base portion 44 and a second overmolded portion 46 configured as the tablet engagement portions 46. In this embodiment the chip carrier 20 is a single integral component 20.

With reference to Figure 2, the overmoulded portion 50 is shown without the integral base portion and comprises the pad engaging portions 46 as well as the incidental portions 52 which constitute flow paths for cast molded material during the molding process. . This portion as shown, reflects the configuration of the mold cavity for the e-mold. In the preferred embodiment, the trough portion or portion 44 will be molded from a readily stable, dimensionally inexpensive molded plastic, such as polycarbonate or polycarbonate with carbon fiber filler. Then, the eo-shaped portion can be molded from another molten processable crystalline plastic, such as PEEK or PEEK with carbon fiber filler. These materials are different with respect to e. its morphological structure and its processing temperatures Another pair of different materials morphologically, could also be used with similar advantages as those provided by these materials. The amorphous material, polycarbonate and the crystalline material, PEEK, form a thermophysical bond when the amorphous material arrives in contact with the crystalline material in the molten state. It is believed that the union is formed by virtue of the increase in the surface energy of the polymer glass at the interface. Therefore, when the hot amorphous melt comes into contact with the polymer glass, the polycarbonate, raises the energy of the surface of the polymer glass and as the hot melt is cooled down, this crystallizes at the interface. It is speculated that the attributes of the crystallization process to the union of the two materials. The dissipation of heat in the polymer glass at a very slow rate due to its low specific heat and thus the hot PEEK melt cooled to a lower ratio increases the crystallinity in the inferium. When this process is carried out in an injection mold, the -formed product will have a higher level of crystallinity at the polymer glass and the crystal than in the inferred from a polymer crystal and the cast steel due to the difference in the specific heat of steel and the glass of polymer In the preferred embodiment, the polycarbonate, which is the polymer glass, should be molded first and then placed back into an injection mold to mold PEEK thereon. In this process the mold temperature is ideally maintained below the glass transition temperature of the polycarbonate which is approximately 149 ° C to prevent distortion of the base portion of the polycarbonate. The tablet contact portion 50 is strategically placed and configured such that the tablet never comes into contact with the polycarbonate.

An alternative amorphous material in which a favorable bond has been observed is polyetherimide (PEI). This bond can have a chemical bonding component. Various types of link components can be involved in the link from the overmoulded portion to the base portion. It is believed that a thermophysical link occurs when the molten overmolded material arrives in contact with the non-molten base portion. The thermophysical link occurs when the molecules of the two portions arrive inside three molecular radii. With reference to Figures 3, 4 and 5, a work-in-progress box is described and is generally indicated with the number 60. Such a box will typically maintain an H-bar shaped bar carrier 62 and has major components of a cover upper 64, a base portion (36), and an H-shaped bar pickup carrier 62 engaged in and seated in the base portion 66. In this case, the "bearer" refers to any of the enclosed box or enclosed box with the H-shaped bar carrier. Various components can be formed in the overmolding process to take advantage of the inherent characteristics and advantages of the process and the invention.For example, in Figure 5, the upper section can be Molded from polycarbonate with the hinge 68 overmolded with PEEK to adhere to the upper cover section 64. Further, with reference to Figure 4, a polycarbonate window 70 may first be molded by a desired configuration and t size and inserted into the mold for the cover portion 64 with rest of the overmolded cover portion to the polycarbonate window. Overmolding allows and provides a high integrity bond without the use of mechanical adhesives or fasteners. With reference to Figures 6 and 7, a magnetic disk-loading carrier is typically comprised of a base portion 76, an upper cover 78, and the portion 79 can be advantageously formed according to the invention, by first molding the portion of support 82 of the base portion 76 and then injection molding the disc coupled to the portions 84. Again, the support portions 82 can be formed of polycarbonate material or the like and the disk contact portions that can be formed of PEEK or similar material. With reference to Figures 8 and 9, a transport module which is intended for use with long semiconductor wafers, is shown, for example, 300 mm. In this particular configuration, the pad support portion 90 is comprised of a base 91 with a machine interface portion 92, the vertical columns 94 with the pad support shelves 96 and an upper portion 98. The tablet engages the shelves which may have an overmolded portion 99 which is the portion that contacts the pellets contained by the transport module. The machine interface can also use an overmolded portion where the equipment is contacted. With reference to Figure 12, an alternative embodiment of a pellet carrier configured as a carrier that increments the process is shown and is indicated generally with the number 110. Such a carrier increases the process having base support portions 112 and 114 as well as arms 116 extending between them. Each of the arms has a plurality of teeth 118 defining grooves 120 for holding pellets during the process steps. In this particular embodiment, the outer portion of the arms 116 and the tooth can be overmolded to a basic base frame 122 to provide the advantages of the invention. With reference to Figures 10 and 11, a composite pellet carrier made of assembled components 122 is described. The components comprise side wall portions 124 as well as a carrier frame 126. The side wall inserts 124 adapted into and coupled to the frame 126 to form a secure and chip carrier mounted. Additionally, a mechanical flange or machine interface 132 may be provided at the rear end 134 of the carrier. In this case, each of the sidewall portions may have overmold pads engaging portions 139 to minimize generation of particles by scraping the pads. The overmoulding may be under adjusted dimensional control that the base portion provides low tolerance placed on the pads. With reference to Figure 13, a schematic view i Lustra a methodology, is shown to achieve the invention. First a mold is provided to make a base or a support portion which can be a carrier frame or other carrier portion such as a side wall base portion 130 as illustrated. The base portion is molded and is then placed in an additional mold or alternatively the same mold with a mold insert removed. Then, the mold is closed and the additional overmoulded material such as PEEK is injected into the mold cavity corresponding to the specific portions that are being overmoulded. Then, the completed portion comprising the base portion and the overmolded portion is removed. If a base portion is a component part, then the component part is mounted within a carrier 136. In particular applications this may be suitable for having the first injection molded portion, the base portion to be relatively smaller volumetric. than the second overmolded portion. In other applications a first material can be deposited at critical positions in a mold, for example, the pad contact areas, the material is approved to solidify, and a second support portion is overmolded onto the first material without changed molds. In other particular applications, the second material does not have to be approved to solidify, the two materials can be joined while both are melted. This coinjection molding can not offer the precision in the location of the interface between the first portion and the second portion.; does, however, eliminate the need for the extra mold and the steps of approving the first portion to solidify, remove the portion of the mold, and place the first portion in the second mold. The present invention may be contained in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desirable that the present embodiment be considered in all respects as illustrative and not restrictive, the reference being made to the appended claims better than the above description to indicate the scope of the invention.

Claims (17)

1. CLAIMS 1. An overmolded pellet carrier having a plurality of slots for holding pellets in an axially aligned configuration, the pellet carrier characterized in that it comprises: a) a base portion formed of a first thermoplastic material; and b) a plurality of pellet contact portions including seated portions of pellets eroded in a base portion, pellet contact portions formed of a second thermoplastic material, pellet contact portions define the plurality of slots, the tablet contact portions linked to the base portion.
2. 2. The overmold tablet carrier according to claim 1, characterized in that the tablet carrier is configured as an H-bar holder.
3. 3. The overmolded tablet carrier according to claim 1, characterized in that it also comprises a container portion for enclosing the tablets.
4. 4. The pellet carrier according to claim 1, characterized in that the base portion comprises polycarbonate and the pellet contact portions include polyetheretherketone.
5. 5. An overmolded pellet carrier having a plurality of slots for supporting pellets in an axially aligned configuration, the pellet carrier comprises an overmolded low particle that generates the coupling component with a surface engaged to couple and uncouple a separate object from the carrier of pellet, the coupled component comprised of a first base portion formed of a first molded plastic and a second overmolded portion attached to the first molded portion, the second overmoulded portion formed of a second moldable plastic having a lower particle that generates characteristics than the first portion.
6. 6. The overmolded pellet carrier according to claim 5, characterized in that the coupled component is an interface portion equipment for coupling with the external equipment.
7. 7. The padded scrim carrier according to claim 5, characterized in that the pad carrier comprises a plurality of coupling components and wherein the coupling components are each configured as a sill support shelf.
8. 8. The overmold tablet carrier according to claim 7, characterized in that it further comprises a door for enclosing the tablet carrier.
9. 9. A process for manufacturing pellet carriers comprising the steps of: a) injecting by molding a base portion of a first plastic into a first mold portion, b) placing the molded base portion in the second mold portion, and c) overmolding a contact portion in the base portion using a second plastic.
10. 10. The process in accordance with the claim 9, characterized in that it further comprises the step of melting a polycarbonate resin as the first plastic.
11. 11. The process according to claim 10, characterized in that it also comprises the steps of melting a resin comprised of one of the sets of polyetheretherketone or polyetherimide as the second plastic.
12. 12. The process according to claim 1, characterized in that it further comprises the addition of carbon fiber to one of the polyetheretherketone or polyetherimide sets.
13. 13. The process in accordance with the claim 10, characterized in that the polycarbonate has a glass transition temperature and further comprises the step of maintaining the temperature of the second mold below the glass transition temperature of the polycarbonate.
14. 14. A pellet carrier comprising a component, the component comprises a first molded portion of a first thermoplastic material and a second portion molded by injection of a second thermoplastic material to the first portion, the first and second portion attached to a thermophysical link .
15. 15. A process for manufacturing the pellet carrier portion characterized in that it comprises: a) injecting a first thermoplastic material into a mold cavity at a predetermined location to form a p >first portion, and b) injecting a second thermoplastic material contacting the first material to form a second portion attached to the first portion forming an integral composite pellet.
16. 16. The process according to claim 15, characterized in that it further comprises the step of authorizing the first portion to solidify before the injection of the second thermoplastic material.
17. 17. The process according to claim L6, characterized in that it further comprises the step of removing the first portion and placing the first portion in a second cavity before the injection of the second material.