METHOD OF MANUFACTURING A MASTER DISC UNIT AND A MATRIX PRODUCED THEREFROM AND ADAPTER RING FOR MANUFACTURING THE MASTER DISC UNIT

Abstract: The present invention relates to a method, starting from a micro-structured substrate disc (18) of a first diameter, of manufacturing a master disc unit intended for the manufacture of a disc-shaped matrix of a second, larger diameter for reproduction of micromechanical products, kinoforms or mirror copies of such a matrix. According to the invention, the micro-structured substrate disc (18) is placed with its structured side (24) against a flat supporting surface (26). Thereafter, a flat, annular element (10) is placed on the flat supporting surface (26) with the annular element (10) coaxially surrounding the substrate disc (18) to form an annular slot between the annular element (10) and the substrate disc (18). The substrate disc (18) and the annular element (10) are joined together by means of an adhesive (28) to form a raw master disc unit. The invention also relates to a method of manufacturing a disc-shaped matrix with the aid of the master disc unit formed. A disc-shaped press matrix can be formed against a metallized side of the master disc unit in a manner known per se by electroplating. The invention also relates to an adapter ring for manufacturing a master disc unit. This ring has flat opposite sides (12, 14), an outer diameter corresponding to or exceeding the outer diameter of the matrix to be manufactured by the master disc unit, and a hole diameter somewhat exceeding the diameter of a structured substrate disc (18) which is to be concentrically surrounded by and joined to the adapter ring (10).

Description: Method of manufacturing a master disc unit and a matrix produced therefrom and adapter ring for manufacturing the master disc unit. The present invention relates to a method of manufacturing a master disc unit, starting from a microstructure substrate disc of a first diameter, said master disc unit being intended for the manufacture of a disc-shaped matrix of a second, larger diameter for reproduction of micromechanical products, kinoforms or the like. In part based on semiconductor technology, new techniques have been developed lately for the production of micromechanical products, such as e.g. valveless micro- fluid pumps, and kinoforms and other microoptical-like conductors and lenses, so- called DOE (Diffractive Optical Elements) and the like. These processes normally start with a disc substrate in the form of a round disc of silicon, quarts or glass, coated with a layer sensitive to light or radiation, which layer is given the desired form-structure by exposure to light or electron beams or by etching. Such discs typically have a standard diameter of 4 inches (101,6 mm) and a thickness of ca. 0,5-1,5 mm. The depth of the cavities formed (the structure depth) in the silicon disc or the disc layer can vary from a few μm in kinoforms up to ca. 500 μm in micromechanical applications. The structured side of the disc substrate is coated in a known manner with a metal layer, for example by spraying or steaming on a thin layer of nickel, to make the structured surface electrically conducting in a subsequent plating phase, in which a matrix is manufactured by nickel-plating, for example, against the metallized, structured disc substrate. The matrix can then be used as a press matrix in an injection moulding machine to manufacture, by known injection moulding technology, plastic discs. The products can be made in multiples on each extruded disc and then be cut out as finished products or components. Alternatively, the matrix can be used as an original or father matrix for further matrix production, i.e. for manufacturing mirror copies thereof, which are in turn used for manufacturing a number of press matrices. When manufacturing such matrices, existing plating equipment for ordinary CD- press matrices has often been used, and existing machines for moulding CDs have often been used for injection moulding. In such plating equipment and injection moulding machines, one normally works with larger diameters (from ca. 130 mm and upwards) in the holders and tools which hold the master discs and the matrices. One purpose of the present invention is to suggest a process which makes it possible to easily adapt the dimensions of structured disc substrates of a certain smaller diameter when manufacturing flat master disc units to a diameter which is larger than the diameter of the disc substrate. For this purpose, the process of the type described by way of introduction is characterized by laying the micro-structured substrate disc with its structured side against a flat supporting surface, laying a flat, annular element, having a hole with an inner diameter somewhat exceeding the diameter of the substrate disc and which has an outer diameter which corresponds to or exceeds the diameter of the press matrix which is to be manufactured by the master disc unit, on the flat supporting surface with the annular element coaxially surrounding the substrate disc so as to form an annular slot between the annular element and the substrate disc, introducing adhesive into the slot, and causing the adhesive to cure into an adhesive joint between the annular element and the substrate disc to form a raw master disc unit. This makes it possible to obtain a master disc unit with a clearly defined plane and with a diameter adapted to standard holders in existing plating equipment for CD- production. This, in turn, makes it possible to manufacture press matrices of standard format, fitting existing CD-injection moulding machines. This provides substantial savings in tooling costs, since existing standard equipment can be used. Preferred embodiments and features of the process according to the invention are disclosed in the subsequent dependent claims 2-10. Within the scope of the present invention, there is included also a process, starting from a micro-structured substrate disc of a first diameter, of manufacturing a discshaped matrix of a second larger diameter for reproduction of micromechanical products, kinoforms or the like, characterized by laying the micro-structured substrate disc with its structured side against a flat supporting surface, laying a flat, annular element having a hole with an inner diameter somewhat exceeding the diameter of the substrate disc and which has an outer diameter corresponding to or exceeding the diameter of the matrix which is to be manufactured, on the flat supporting surface with the annular element coaxially surrounding the substrate disc so as to form an annular slot between the annular element and the substrate disc, introducing an adhesive into the slot, causing the adhesive to cure into an adhesive joint between the annular element and the substrate disc to form a raw master disc unit, coating the structured surface of the substrate disc and the coplanar surface of the annular element and the adhesive joint with a thm metal layer to form a fmished master disc unit, and moulding against the metallized side of the master disc unit a disc-shaped matrix in a manner known per se by electroplating. The invention also relates to an adapter ring for manufacturing a master disc unit intended for the manufacture of a disc-shaped matrix for reproduction of micro- mechanical products, kinoforms or the like, characterized by having flat opposite surfaces, an outer diameter corresponding to or exceeding the outer diameter of the matrix which is to be manufactured by the master disc unit, and a hole diameter somewhat exceeding the diameter of a structured substrate disc which is to be concentrically surrounded by and joined to the adapter ring. The invention will be described in more detail below with reference to the accompanying drawing, in which: Fig. 1 is a cross sectional view through an adapter ring according to the invention for use in manufacturing a master disc unit for a press matrix for reproduction of micromechanical products, kinoforms or the like; and Fig. 2 shows on an enlarged scale a partial section through the adapter ring of Fig. 1 joined to a structured substrate disc. In Figs. 1 and 2, 10 generally designates an adapter ring which has flat surfaces 12 and 14, and an outer diameter of e.g. 200 mm and a thickness of 6 mm. The ring 10 has a central, cylindrical hole 16 with an inner diameter which exceeds, by one or a few tenths of a millimeter, the outer diameter of a structured substrate disc 18 (Fig. 2) which is to be joined to the ring 10. The depth d of the hole 16 corresponds essentially to the thickness of the substrate disc 18 (e.g. 1,5 mm). The hole 16 opens upwards in a widened hole portion 20, which is defined by a conical hole wall 22, which can have an inclination of for example ca. 45° relative to the plane of the ring 10. The substrate disc 18, which can consist of a silicon disc or a quartz or glass disc of standard format (diameter ca. 100 mm), which is coated with a layer which is sensitive to light or radiation, carries on one side a structuring 24 with a configuration corresponding to the product which is to be reproduced with the aid of a press matrix manufactured in accordance with the invention, in an injection moulding machine of standard type for CD-discs. A process according to the invention for manufacturing a master disc unit, intended for the manufacture of a disc-shaped matrix for reproduction of micromechanical products, kinoforms or mirror copies of the matrix, will now be described. A structured substrate disc 18 is laid on a flat supporting surface 26 with its structured surface 24 facing the supporting surface 26. The supporting surface 26 can have a surface of silicon rubber or consist of another solid material and be coated with e.g. a plastic film of Teflon ® (not shown) to obtain suitable sealing and release proper- ties. The adapter ring 10 is then placed concentrically over the substrate disc 18 so that a narrow annular slot (ca. 0,1-0,3 mm) is formed between the outer periphery of the substrate disc 18 and the hole 16 in the ring 10. The ring 10 and the substrate disc 18 are caused to be in intimate contact with the silicon rubber surface 26 (or the plastic film), in order to prevent the adhesive 28, which in a subsequent step is introduced into the annular slot, penetrates to the undersurface 12 of the ring 10 and the substrate disc 18 and adheres to the supporting surface. After application of the adhesive 28, it is cured by means of UV-light, for example. When the adhesive 28 has been completely cured, the "raw" master disc unit thus formed is transferred to a metallization station (not shown), where a thin (ca. 10- 100 nm) metal layer of nickel, for example, is sputtered or steamed over the structured surface of the substrate disc and over the adhesive joint surface and the underside 12 of the ring 10. Thus, a fmished master disc unit is obtained with a dimension suited to electroplating in existing plating equipment for making press matrices for CD-discs. When the transport of the "raw" master disc units to the metallization station is long in time or distance, a process is required where a plastic film is allowed to remain over the structured surface of the master disc unit for protective purposes. After manufacturing the finished, metallized master disc units, they can be trans- ferred to or be mounted in an electroplating plant with standard holders, where matrices of nickel, for example, are mounted against the structured side of the master disc unit, whereafter the matrices in a subsequent step are surface-treated on their reversed sides to a smoothness of preferably Ra < 0,1 urn and are provided with a centre hole of standard format and are edge-cut at the outer periphery to the desired standard diameter for injection moulding machines intended for CD- production. If the substrate disc has relatively deep (up to ca. 500 μm), depressions in its structured surface, one can expect with present plating methods relatively large variations on the reverse side of the matrix produced. In order to provide the necessary support of the substrate disc 18 when the reverse side is to be machined flat, requiring that the master disc unit and the matrix be turned upside down in a machining station, it can be suitable to fill the entire widened hole portion 20 with adhesive or other material, up to the surface 14 of the ring 10. Although the attached independent method claims disclose that the annular element is placed on the flat supporting surface to coaxially surround the substrate disc, the person skilled in the art will understand that this sequence can be reversed, i.e. that the annular element can be first placed on the supporting surface and the substrate disc thereafter be placed coaxially in the hole in the annular element. The steps a) and b) can thus be reversed with an equivalent result.

Claims: Claims 1. Method, starting from a micro-structured substrate disc (18) of a first diameter, of manufacturing a master disc unit, intended for manufacturing a disc-shaped matrix of a second, larger diameter, for reproduction of micromechanical products, kinoforms or mirror copies of such a matrix, characterized by a) laying the micro-structured substrate disc (18) with its structured side (24) against a flat supporting surface (26), b) laying a flat, annular element (10), having a hole (16) with an inner diameter somewhat exceeding the diameter of the substrate disc (18) and which has an outer diameter which corresponds to or exceeds the diameter of the press matrix which is to be manufactured by the master disc unit, on the flat supporting surface (26) with the annular element (10) coaxially surrounding the substrate disc (18) so as to form an annular slot between the annular element (10) and the substrate disc (18), c) introducing adhesive (28) into the slot, and d) causing the adhesive (28) to cure into an adhesive joint between the annular element (10) and the substrate disc (18) to form a raw master disc unit. 2. Method according to Claim 1, characterized in that the substrate disc (18) and the annular element (10) are laid on the flat supporting surface (26) with an intermediate layer of a sealing and protective plastic film. 3. Method according to Claim 1, characterized in that the structured surface (24) of the substrate disc (18) and the coplanar surface (12) of the annular element (10) and the adhesive joint (28) are coated with a thin metal layer to form a fmished master disc unit. 4. Method according to Claim 2, characterized in that the plastic film is removed, whereafter a thin metal layer is applied on the structured surface of the substrate disc (18) and on the coplanar surface (12) of the annular element (10) and the adhesive joint (28) to form a finished master disc unit. 5. Method according to one of Claims 1-4, characterized in that the adhesive (28) is cured with the aid of UV-light. 6. Method according to one of Claims 1-5, characterized in that the flat, annular element (10) is selected with a thickness exceeding the thickness of the substrate disc (18). 7. Method according to Claim 6, characterized in that the slot-forming hole (16) in the annular element (10), which concentrically surrounds the substrate disc (18), has a depth (d) essentially corresponding to the thickness of the substrate disc (18), the annular element (10) having a widened hole portion (20,22) adjacent the slot- forming hole (16). 8. Method according to Claim 7, characterized in that, in addition to insertion of the adhesive (28) in the slot, the widened hole portion (20,22) is also filled with adhesive or other material. 9. Method according to one of Claims 1-8, characterized in that the width of the slot is selected as one or several tenths of a millimeter. 10. Method according to one of Claims3-8, characterized in that the thin metal layer is applied by sputtering or steaming on of nickel, for example. 11. Method, starting from a micro-structured substrate disc (18) of a first diameter, of manufacturing a disc-shaped matrix of a second larger diameter for reproduction of micromechanical products, kinoforms or mirror copies of such a matrix, characterized by a) laying the substrate disc (18) with its structured side (24) against a flat supporting surface (26), b) laying a flat, annular element (10) having a hole (16) with an inner diameter somewhat exceeding the diameter of the substrate disc (18) and which has an outer diameter corresponding to or exceeding the diameter of the matrix which is to be manufactured, on the flat supporting surface (26) with the annular element (10) coaxially surrounding the substrate disc (18) so as to form an annular slot between the annular element (10) and the substrate disc (18), c) introducing an adhesive (28) into the slot, d) causing the adhesive (28) to cure into an adhesive joint between the annular element (10) and the substrate disc (18) to form a raw master disc unit, e) coating the structured surface (24) of the substrate disc (18) and the coplanar surface (12) of the annular element (10) and the adhesive joint (28) with a thin metal layer to form a fmished master disc unit, and f) moulding against the metallized side of the master disc unit a disc-shaped matrix in a manner known per se by electroplating. 12. Method according to Claim 11, characterized in that plated matrix is machined on its reverse side to a surface smoothness of Ra < 0,1 μm. 13. Method according to Claim 11 or 12, characterized in that the plated matrix is provided in a manner known per se with a centre hole and is edge-cut to the desired outer diameter. 14. Adapter ring for manufacturing a master disc unit intended for the manufacture of a disc-shaped matrix for reproduction of micromechanical products, kinoforms or mirror copies of such a matrix, characterized in that it has a) two opposite surfaces (12,14), of which at least one (12) is flat and smooth, b) an outer diameter corresponding to or exceeding the outer diameter of the matrix which is to be manufactured by the master disc unit, and c) a hole diameter somewhat exceeding the diameter of a structured substrate disc (18) which is to be concentrically surrounded by and joined to the adapter ring (10). 15. Adapter ring according to Claim 14, characterized in that the hole (16) in the ring has a widened hole portion (20,22).

Inventors: BILLMAN AAKE, BILLMAN, AAKE
Applicants: BILLMAN AAKE, TOOLEX ALPHA AB, BILLMAN, AAKE
Application year: 1998
Main classification: G11B7
IPC codes: B29D11, B29D17, G11B7