WIRE EDM PROCESSING DEVICE, WIRE EDM PROCESSING PROCESS AND WAFER MANUFACTURING PROCESS

Abstract

A wire EDM machining device comprises: a pair of machining fluid flow straightening plates, which are conductive and connected to a power supply and are provided in contact with both sides of a workpiece to enclose the workpiece; a pair of nozzles (7a, 7b) into which a plurality of cutting wire parts (1b) is inserted, wherein the pair of nozzles (7a, 7b) includes a plurality of machining fluid ejection holes (7c) which eject a machining fluid towards a space enclosed between the pair of machining fluid flow straightening plates to supply the machining fluid to a gap between the plurality of cutting wire parts (1b) and the workpiece (W); a cutting feed table which moves the pair of machining fluid flow straightening plates up and down relative to the plurality of cutting wire parts (1b);a workpiece holding unit (72) which holds the workpiece (W) to be cut during cutting above the workpiece (W) and the plurality of cutting wire parts (1b); and a lower workpiece holding section which has conductivity and comes into contact with the workpiece (W) from below to hold the workpiece (W).

Description

Area

[0001] The present disclosure relates to a wire electrical discharge machining apparatus that performs wire electrical discharge machining in which a plurality of plate members are collectively cut out from a workpiece using a wire electrode, a wire electrical discharge machining method, and a wafer manufacturing method. background

[0002] In a multi-wire electrical discharge machining device, an electric discharge is generated between a plurality of wire electrodes and a workpiece, and a plurality of plate elements are cut out from the workpiece together. As the plurality of plate elements are simultaneously cut by electrical discharge machining, a plurality of grooves are formed in the workpiece at positions corresponding to wire cutting portions, which are a plurality of sections of the wire electrodes. Then, the wire cutting portions each penetrate into a corresponding one of the plurality of grooves, thereby providing deeper grooves. When the grooves finally reach an edge of the workpiece, a plurality of thin plates are simultaneously produced.

[0003] Heat energy and machining residues resulting from the electrical discharge are constantly generated between the thin plates being produced, that is, in a machining gap, during electrical discharge machining. Both heat energy and machining residues resulting from the electrical discharge are factors in unstable electrical discharge machining. Therefore, for the purpose of discharging machining residues and cooling between electrodes, an attempt is made to supply a machining fluid from a machining fluid supply device via a machining fluid nozzle between electrodes to eliminate a machining destabilizing element. And in order to properly supply the machining fluid between the electrodes, the machining fluid nozzle is arranged as close as possible to the workpiece so that the machining fluid is properly supplied between the electrodes.

[0004] For example, Patent Literature 1 discloses a configuration in which, in a wire electrical discharge machining apparatus that machines a workpiece by applying a voltage to a gap formed between a wire electrode and the workpiece in a machining fluid and generating an electric discharge, with respect to heat energy and machining residues resulting from the electric discharge that are generated in a machining gap during electrical discharge machining, a machining fluid is discharged from a machining fluid supply device via a machining fluid nozzle for the purpose of cooling between electrodes and discharging the machining residues between the electrodes, and the machining fluid nozzle is brought as close as possible to the workpiece to appropriately supply the machining fluid between the electrodes to workpieces.

[0005] Patent Literature 2 discloses a holding device in electrical discharge machining in which a blank is cut at an interval where wires are arranged in parallel. The holding device includes a holding unit that holds the blank and an energizing unit that energizes the blank so that a current flows through the blank. An object of this holding device is as follows: while holding the blank in a region where electrical discharge machining takes place so that it does not fall, a region where electrical discharge machining takes place in the presence of both the blank holding unit and the blank made of different materials is eliminated, thereby reducing instability of electrical discharge machining due to simultaneous electrical discharge to those made of different materials, preventing wire breakage, and stabilizing machining. List of citationsPatent literature Patent literature 1: WO 2020 / 213040 A1 Patent Literature 2: Japanese Patent Application No. 2015-120235 Brief description of the inventionProblem to be solved by the invention

[0006] In Patent Literature 1, a method for fixing a workpiece includes increasing a contact area with a cut-out end face fixing block installed on a chuck and increasing a holding force against shaking of each thin plate during the working process. The workpiece is fixed using a flat alignment portion of the workpiece with a conductive adhesive or the like. Furthermore, energization may be performed from the cut-out end face fixing block, so a power supply path to the workpiece should not be interrupted until the thin plate cutting is completed.However, when the workpiece is fixed only at a machining end portion, as the diameter of thin plates to be machined increases, it is necessary to greatly decrease the flow rate of a machining fluid to prevent cracking of the thin plates, and there is a possibility that a speed of electrical discharge machining decreases rapidly due to faulty discharge of machining residues or insufficient wire cooling.

[0007] In Patent Literature 2, electrical discharge machining is performed while lowering a workpiece toward a wire electrode, and therefore, it is considered that the weight of the thin plate itself decreases due to a decrease in the bending rigidity of each thin plate due to an increase in diameter. However, in a case where the method of Patent Literature 2 is applied to Patent Literature 1, this application reveals a structure in which deflection of the thin plates due to pressure of a machining fluid flow is reduced by a holding unit and two facing wafer holders.In particular, such a wafer holder is made of a urethane or sponge-like material, and when receiving a strong processing fluid flow, the material itself deforms or shifts with respect to outer peripheral surfaces of the thin plates, and is arranged to press the thin plates at a position away from cutting end portions of the thin plates, and therefore it is difficult to prevent cracking at the end of cutting due to deflection of the thin plates having a large diameter.

[0008] The present disclosure has been made in view of the foregoing, and an object thereof is to provide a wire electrical discharge machining apparatus capable of preventing damage to thin plates when the thin plates are cut out. Ways to solve the problem

[0009] To solve the problems described above and achieve the object, a wire electrical discharge machining apparatus according to the present disclosure is a wire electrical discharge machining apparatus that generates an electric discharge between a plurality of cutting wire parts that revolve and a workpiece, to perform electrical discharge machining on the workpiece with energy generated by the electric discharge, and simultaneously cut a plurality of wafers from the workpiece. The wire electrical discharge machining apparatus includes a wire electrode including the plurality of cutting wire parts that are spaced apart in parallel from each other and face the workpiece; a power supply unit that generates an electric discharge between the plurality of cutting wire parts and the workpiece; anda pair of machining fluid flow rectifying plates having conductivity, connected to a power supply, and provided in contact with both sides of the workpiece to enclose the workpiece; and a pair of nozzles into which the plurality of cutting wire members are inserted, the pair of nozzles including a plurality of machining fluid ejection holes that eject a machining fluid toward a space enclosed between the pair of machining fluid flow rectifying plates to supply the machining fluid to a gap between the plurality of cutting wire members and the workpiece. The wire discharge machining apparatus includes a cutting feed table that moves the pair of machining fluid flow rectifying plates up and down relative to the plurality of cutting wire members;a workpiece holding unit that holds the workpiece to be cut from above the workpiece and the plurality of cutting wire pieces during cutting; and a lower workpiece holding portion that has conductivity and comes into contact with the workpiece from below to hold the workpiece. Effects of the invention

[0010] A wire electrical discharge machining apparatus according to the present disclosure achieves an effect that it is possible to prevent damage to thin plates when the thin plates are cut out. Short description of the drawings Fig. 1 is a conceptual diagram illustrating an exemplary configuration of a wire electric discharge machining apparatus according to a first embodiment. Fig. 2 is a perspective view illustrating a thin plate machining stabilizing unit included in the wire electric discharge machining apparatus according to the first embodiment, and a positional relationship between the thin plate machining stabilizing unit and mechanisms around the thin plate machining stabilizing unit. Fig. 3 is a cross-sectional view illustrating an internal configuration of the stabilizing unit for thin plate machining included in the wire electric discharge machining apparatus according to the first embodiment. Fig. 4 is a diagram illustrating a supply path of a power supply for electrical discharge machining from a machining power supply to a workpiece in the wire electrical discharge machining apparatus according to the first embodiment. Fig. 5 is a block diagram illustrating an exemplary configuration of a control unit included in the wire electric discharge machining apparatus according to the first embodiment. Fig. 6 is a flowchart illustrating an operation of the wire electric discharge machining apparatus according to the first embodiment during cutting. Fig. 7 is a first perspective view illustrating a state of thin plates during cutting in the thin plate machining stabilizing unit included in the wire electric discharge machining apparatus according to the first embodiment. Fig. 8 is a second perspective view illustrating the state of the thin plates during cutting in the thin plate machining stabilizing unit included in the wire electric discharge machining apparatus according to the first embodiment. Fig. 9 is a set of diagrams for explaining a relationship between a cutting position and a cutting length of the workpiece during cutting by the wire electric discharge machining apparatus according to the first embodiment. Fig. 10 is a schematic view illustrating an exemplary configuration of a workpiece power supply support section included in a wire electric discharge machining apparatus according to a second embodiment. Fig. 11 is a conceptual diagram illustrating an example of a state of the thin plates immediately before the completion of cutting in the wire electric discharge machining apparatus according to the first embodiment. Fig. 12 is an enlarged view showing a specific area in Fig. 11 illustrates. Fig. 13 is a conceptual diagram illustrating an example of a state of thin plates immediately before completion of cutting in the wire electric discharge machining apparatus according to the second embodiment. Fig. 14 is an enlarged view showing a specific area in Fig. 13 illustrates. Fig. 15 is a schematic view illustrating an exemplary configuration of thin plate side surface holding portions of a thin plate machining stabilizing unit included in a wire electric discharge machining apparatus according to a third embodiment. Fig. 16 is an enlarged view showing a specific area in Fig. 15 illustrates. Fig. 17 is another enlarged view showing the specific area in Fig. 15 illustrates. Fig. 18 is a diagram illustrating a hardware configuration in a case where functions of the control unit included in each of the wire electric discharge machining devices are implemented by dedicated hardware. Fig. 19 is a diagram illustrating a hardware configuration in a case where the Fig. 18, the functions of the control unit included in each of the wire-cutting machining apparatuses are implemented by a processor executing a program stored in a memory. Description of embodiments

[0011] Hereinafter, a wire electrical discharge machining apparatus, a wire electrical discharge machining method, and a wafer manufacturing method according to each embodiment will be described in detail with reference to the drawings. First embodiment.

[0012] A multi-wire electrical discharge machining apparatus is used, for example, in a semiconductor manufacturing step for dicing, in which a plurality of semiconductor wafers are cut collectively from a blank, that is, for collectively cutting the plurality of semiconductor wafers. As the collective cutting progresses, thin plates are cut from the blank in the collective cutting process, a portion of thin plates to become semiconductor wafers increases, and a portion integrated with the blank decreases. Then, immediately before the completion of the collective cutting, adjacent thin plates are in a state where they are only connected to each other via a small remaining processing portion that has not yet been processed.

[0013] The thin plates in this state are shaken by a flow of machining fluid supplied between electrodes, i.e., into a gap between the blank and a wire. Especially when, for example, a thin plate has a diameter of 6 inches or more, combined with the influence of the weight of the thin plate itself, deflection of the thin plate occurs. As a result, especially for a thin plate that has a large diameter relative to a plate thickness, stress due to deflection is concentrated near a remaining machining portion, and cracking is likely to occur from the remaining machining portion.Even for super-hard materials that have relatively high hardness, such as silicon carbide (SiC) and gallium nitride (GaN), when the diameter of a semiconductor wafer increases with respect to its thickness, the semiconductor wafer is shaken or deflected due to a decrease in the rigidity of the semiconductor wafer itself or due to a force received from the processing fluid flow.

[0014] In the case of a semiconductor wafer, cracking or chipping, even in a portion of the semiconductor wafer, leads to problems such as a decrease in production yield in a polishing step of a diced semiconductor wafer or in a semiconductor manufacturing process after the polishing step. Therefore, cracking or chipping in a semiconductor wafer is a factor that significantly affects the commercial value of the semiconductor wafer.

[0015] That is, in electrical discharge machining in which a plurality of plate members are cut collectively from a workpiece using a wire electrode, in order to improve discharge of machining residues generated by electric discharge and cooling of a wire heated by electric discharge energy, a flow rate of a machining fluid supplied to a gap between the thin plates in the cutting process is increased, the thin plates are shaken due to an increase in pressure of the machining fluid flow received by a portion of thin plates, and each thin plate in the cutting process becomes gradually susceptible to bending due to a decrease in bending rigidity of the thin plate itself due to an increase in diameter with respect to a thickness of the thin plate.

[0016] Then, the pressure of the machining fluid flow acts on the thin plates, and stress concentration occurs at the boundary between the formed thin plate portion and the remaining machining portion of the workpiece, or near a portion where cutting into the thin plates is nearing completion, so cracking or chipping of the thin plates is likely to occur. For example, in a case where the workpiece is a blank made of a crystal of SiC or GaN, with the increasing diameter and diameter dimension of a semiconductor wafer, the influence of fluid pressure that a thin plate portion receives from a machining fluid flow during electrical discharge machining or the influence of a decrease in rigidity becomes significant.

[0017] Hereinafter, not only a thin plate cut off by cutting is referred to as a wafer, but also a workpiece in which a machined groove is formed, that is, a thin plate-like portion which is a part of the workpiece and has not yet been cut off, is referred to as “a wafer”, “a machined wafer” or the like.

[0018] Fig. 1 is a conceptual diagram illustrating an exemplary configuration of a wire electric discharge machining apparatus 1000 according to a first embodiment. Fig. 2 is a perspective view illustrating a thin plate machining stabilizing unit 70 included in the wire electric discharge machining apparatus 1000 according to the first embodiment, and a positional relationship between the thin plate machining stabilizing unit 70 and mechanisms around the thin plate machining stabilizing unit 70. Fig. 3 is a cross-sectional view illustrating an internal configuration of the stabilizing unit 70 for thin plate machining included in the wire electric discharge machining apparatus 1000 according to the first embodiment. Fig. 3 illustrates a state in which wire electric discharge machining has progressed to a position corresponding to about 1 / 3 of a total machining path with respect to a workpiece W installed on a machining fluid flow rectifying plate 71. Fig. Figure 3 illustrates a cross section at a position between a machining fluid flow rectifying plate 71a and a machining fluid flow rectifying plate 71b, which will be described later. Wire electrical discharge machining apparatus 1000 is a multi-wire electrical discharge machining apparatus that performs electrical discharge machining using a wire electrode 1. Fig. 2 and Fig. 3, each arrow 81 indicates a running direction of the cutting wire parts 1b. In Fig. 3, each arrow 82 indicates a direction of machining fluid flow.

[0019] Fig. 1 illustrates an x-axis, a y-axis, and a z-axis of a three-axis Cartesian coordinate system. A y-axis direction corresponds to a running direction of the wire electrode 1 on the workpiece W, that is, the running direction of the wire electrode 1 with respect to the workpiece W arranged in the wire discharge machining apparatus 1000. A z-axis direction corresponds to a height direction of the wire discharge machining apparatus 1000. The height direction of the wire discharge machining apparatus 1000 corresponds to an up-and-down direction, that is, a vertical direction. An x-axis direction corresponds to a direction in which portions of the wire electrode 1 are arranged parallel to each other on the workpiece W, that is, a direction in which the portions of the wire electrode 1 are arranged parallel to each other with respect to the workpiece W arranged in the wire discharge machining apparatus 1000.The x-axis direction may be referred to as a direction parallel to a longitudinal direction of the workpiece W arranged in the wire electrical discharge machining apparatus 1000.

[0020] The wire electrical discharge machining apparatus 1000 includes a machining mechanism unit 100 that performs electrical discharge cutting on the workpiece W with the wire electrode 1, a power supply unit 200 that performs power supply, and a control unit 300 that controls the wire electrical discharge machining apparatus 1000. The wire electrical discharge machining apparatus 1000 cuts a plurality of plate members collectively from the workpiece W. Examples of the material for the workpiece W include tungsten, molybdenum, silicon carbide, monocrystalline silicon, monocrystalline silicon carbide, gallium nitride, and polycrystalline silicon. Silicon carbide may be referred to as "tanka-keiso" in Japanese. Hereinafter, electrical discharge cutting may be simply referred to as cutting.

[0021] The machining mechanism unit 100 includes a plurality of guide rollers 2, spools 3, damping guide rollers 4a and 4b, nozzles 7a and 7b, spool rotation controllers 8a and 8b, lateral controllers 9a and 9b, and a cutting feed table 10. The plurality of guide rollers 2 includes a guide roller 2a, a guide roller 2b, a guide roller 2c, and a guide roller 2d. The spools 3 include a spool 3a and a spool 3b.

[0022] The plurality of guide rollers 2 guide the running of the wire electrode 1. The guide rollers 2a, 2b, 2c, and 2d are each installed so as to be rotatable about a rotational axis corresponding thereto. The guide rollers 2a, 2b, 2c, and 2d are spaced apart from each other and arranged so that their rotational axes are parallel to each other. Since the rotational axes of the guide rollers 2a, 2b, 2c, and 2d are parallel to each other, the wire electrode 1 can run with high precision. The rotational axes of the guide rollers 2a, 2b, 2c, and 2d are arranged parallel to the x-axis.

[0023] A wire electrode 1 is wound several times around the guide rollers 2a, 2b, 2c, and 2d at intervals in a direction of the rotation axis of each of the guide rollers 2a, 2b, 2c, and 2d. These portions of the wire electrode 1 are collectively referred to as parallel wire portions 1a. Portions of the parallel wire portions 1a facing the workpiece W are each referred to as a cutting wire portion 1b. The cutting wire portions 1b include a plurality of portions of the wire electrode 1 arranged in parallel. The cutting wire portions 1b are preferably installed parallel to each other.

[0024] A plurality of guide grooves 2e are formed at equal intervals on the surfaces of the guide rollers 2a, 2b, 2c, and 2d. By winding the wire electrode 1 around the surfaces of the guide rollers 2a, 2b, 2c, and 2d along the plurality of guide grooves 2e, the guide rollers 2a, 2b, 2c, and 2d maintain the distance between the portions of the wire electrode 1, that is, the distance between the portions of the wire electrode 1 of the parallel wire parts 1a, constant. In the wire discharge machining apparatus 1000, the cutting wire parts 1b are arranged parallel to each other and at equal intervals, so that the plate thicknesses of the plurality of plate elements cut from the workpiece W can be equalized, and the cross sections of the plurality of plate elements can be made parallel to each other. Regarding the plurality of guide rollers 2, the number thereof is not necessarily four, and may be three or fewer, or five or more.

[0025] The coils 3a and 3b cause the wire electrode 1 to run through a process of unwinding the wire electrode 1 and a process of winding the wire electrode 1. The coil 3a performs the process of unwinding the wire electrode 1. The coil 3b performs the process of winding the wire electrode 1. The coil rotation control device 8a and the transverse control device 9a control the coil 3a. The coil rotation control device 8b and the transverse control device 9b control the coil 3b.

[0026] The coil rotation control device 8a controls the rotation of the coil 3a and controls the running of the wire electrode 1. The coil rotation control device 8a controls, for example, a running direction and a running speed of the wire electrode 1. The coil rotation control device 8b controls the rotation of the coil 3b and controls the running of the wire electrode 1. The coil rotation control device 8b controls, for example, the running direction and running speed of the wire electrode 1.

[0027] The transverse control device 9a controls a position of the coil 3a in the x-axis direction according to an unwinding position of the wire electrode 1. The transverse control device 9b controls a position of the coil 3b in the x-axis direction according to a winding position of the wire electrode 1. The position control of the coils 3a and 3b by the transverse control devices 9a and 9b is referred to as transverse control. Through the transverse control, the coils 3a and 3b can cause the wire electrode 1 to run stably and with high precision.

[0028] The wire electrode 1 unwound from the spool 3a is wound around the guide roller 2b, the guide roller 2a, the guide roller 2d, and the guide roller 2c in this order, and then the winding continues from the guide roller 2b. The wire electrode 1 is wound onto the spool 3b after passing through the guide rollers 2a, 2b, 2c, and 2d several times in the manner described above.

[0029] The workpiece W is fixed inside the thin plate machining stabilization unit 70. The thin plate machining stabilization unit 70 will be described in detail later. The thin plate machining stabilization unit 70, in which the workpiece W is fixed, is installed between the damping guide roller 4a and the damping guide roller 4b. The damping guide rollers 4a and 4b restrict the movement of the wire electrode 1 in the z-axis direction, thereby reducing vibration of the wire electrode 1 in the cutting wire parts 1b. Although it was described above that the portions of the parallel wire parts 1a facing the workpiece W are each referred to as the cutting wire part 1b, the portions of the parallel wire parts 1a between the damping guide roller 4a and the damping guide roller 4b are also each referred to as the cutting wire part 1b.In the wire electric discharge machining apparatus 1000, the damping guide roller 4a and the damping guide roller 4b may be omitted.

[0030] The nozzle 7a is arranged between the damping guide roller 4a and the thin plate machining stabilization unit 70. The nozzle 7b is arranged between the damping guide roller 4b and the thin plate machining stabilization unit 70. The insides of the nozzles 7a and 7b are filled with the machining fluid supplied from a machining fluid supply pipe 74. The nozzles 7a and 7b include a plurality of machining fluid ejection holes 7c through which the machining fluid filled in the nozzles 7a and 7b is ejected toward the workpiece W in the thin plate machining stabilization unit 70. The parallel wire parts 1a run while being inserted into the plurality of machining fluid ejection holes 7c of the nozzles 7a and 7b.

[0031] The cutting feed table 10 changes the relative positions of the workpiece W and the cutting wire parts 1b. Specifically, the cutting feed table 10 changes the relative positions of the thin plate machining stabilizing unit 70, in which the workpiece W is installed and fixed, and the cutting wire parts 1b. In the first embodiment, it is assumed that the positions of the cutting wire parts 1b are fixed in the z-axis direction, and the cutting feed table 10 is movable in the z-axis direction. The cutting feed table 10 moves components inside the thin plate machining stabilizing unit 70 in the up-and-down directions along with the workpiece W.By moving the cutting feed table 10 in the up-and-down direction, the wire electric discharge machining apparatus 1000 causes the workpiece W installed in the thin plate machining stabilizing unit 70 to approach or separate from the cutting wire parts 1b relative to each other, thereby cutting the workpiece W. Furthermore, a machined groove Wg, which will be described later, is formed along each of the cutting wire parts 1b in the workpiece W by the electrical discharge machining. Note that the cutting feed table 10 may be movable in the x-axis direction, the y-axis direction, and the z-axis direction.

[0032] The machining mechanism unit 100 may include components such as a deflection pulley that reduces vibration of the wire electrode 1, a load cell that measures a tension of the wire electrode 1, and a dancer pulley that controls the tension of the wire electrode 1. The machining mechanism unit 100 can maintain the tension of the wire electrode 1 within a range suitable for the wire electrode 1 to pass through the load cell and the dancer pulley. For example, the dancer pulley can control the tension of the wire electrode 1 by changing an unwinding speed and a winding speed of the wire electrode 1.

[0033] The power supply unit 200 includes a machining power supply 5 and power supply contact units 6a and 6b. The machining power supply 5 supplies power to the wire electrode 1 via the power supply contact units 6a and 6b. The machining power supply 5 also supplies power to the workpiece W via the machining fluid flow rectifying plate 71a.

[0034] The thin plate machining stabilizing unit 70 is a mechanism unit that prevents a power supply failure to each thin plate during cutting. The thin plate machining stabilizing unit 70 is arranged between the damping guide roller 4a and the damping guide roller 4b, and between the nozzle 7a and the nozzle 7b. The thin plate machining stabilizing unit 70 includes the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b, which are a pair of machining fluid flow rectifying plates 71, a workpiece holding unit 72, a workpiece power supply support section 73, thin plate side surface holding sections 75a and 75b, and a workpiece holding unit holder 78, which will be described later.

[0035] The machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b, which are the pair of machining fluid flow rectifying plates 71, have conductivity and are arranged parallel to the running direction of the cutting wire parts 1b, and evenly direct the flow of the machining fluid. The machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b are arranged between the nozzle 7a and the nozzle 7b. The machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b have a plate shape or a rectangular parallelepiped shape and are arranged so that their facing surfaces are parallel.That is, a facing surface 71as, which is a surface of the machining fluid flow rectifying plate 71a facing the machining fluid flow rectifying plate 71b, and a facing surface 71bs, which is a surface of the machining fluid flow rectifying plate 71b facing the machining fluid flow rectifying plate 71a, are parallel. The facing surface 71as of the machining fluid flow rectifying plate 71a and the facing surface 71bs of the machining fluid flow rectifying plate 71b are parallel to the running direction of the cutting wire parts 1b. The facing surface 71as and the facing surface 71bs are, for example, vertical surfaces.

[0036] The machining fluid flow rectifying plate 71a is a first machining fluid flow rectifying plate of the pair of machining fluid flow rectifying plates 71 and is connected to the machining power supply 5. Therefore, the electrical discharge machining power from the machining power supply 5 is supplied to the workpiece W, the workpiece power supply support portion 73, and the side surface holding portions 75a and 75b of the thin plate via the machining fluid flow rectifying plate 71a.Consequently, the supply of the electrical discharge machining power to the workpiece W is performed not only by the power supply to the workpiece W from the machining fluid flow rectifying plate 71a in contact with an end surface of the workpiece W, but also by the power supply to the workpiece W from the workpiece power supply supporting portion 73 and the thin plate side surface holding portions 75a and 75b in contact with the machining fluid flow rectifying plate 71a.

[0037] The machining fluid flow rectifying plate 71b is a second machining fluid flow rectifying plate of the pair of machining fluid flow rectifying plates 71, and is arranged parallel to the machining fluid flow rectifying plate 71a in a state where the workpiece W, the workpiece power supply supporting portion 73, and the thin plate side surface holding portions 75a and 75b fixed to the machining fluid flow rectifying plate 71a are sandwiched between the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b.That is, the workpiece W, the workpiece power supply support portion 73, and the thin plate side surface holding portions 75a and 75b fixed to the machining fluid flow rectifying plate 71a are sandwiched between the facing surface 71as of the machining fluid flow rectifying plate 71a and the facing surface 71bs of the machining fluid flow rectifying plate 71b, which are arranged parallel to each other.

[0038] The machining fluid flow rectifying plate 71b is in close contact with the workpiece W and, together with the machining fluid flow rectifying plate 71a, forms a flow path for guiding the machining fluid supplied from the nozzles 7a and 7b to the workpiece W. The machining fluid is supplied from the nozzles 7a and 7b to a gap between the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b toward the workpiece W. The machining fluid discharged from the plurality of machining fluid discharge holes 7c of the nozzles 7a and 7b is guided to the workpiece W through the facing surface 71as of the machining fluid flow rectifying plate 71a and the facing surface 71bs of the machining fluid flow rectifying plate 71b.That is, the facing surface 71as of the machining fluid flow rectifying plate 71a and the facing surface 71bs of the machining fluid flow rectifying plate 71b regulate the flow of the machining fluid supplied to the gap between the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b in the x-axis direction and form a flow path that guides the flow of the machining fluid to the workpiece W.

[0039] Consequently, the diffusion of the machining fluid in the thickness direction of the thin plates during the cutting process, i.e., in the x-axis direction, is reduced. The cutting wire parts 1b run while being inserted into the plurality of machining fluid ejection holes 7c of the nozzles 7a and 7b. Consequently, the machining fluid easily enters a gap between the cutting wire parts 1b and the workpiece W.

[0040] In the wire electric discharge machining apparatus 1000, since the flow of the machining fluid supplied from the nozzles 7a and 7b is rectified as described above, the diffusion of the machining fluid is reduced, thereby reducing a risk that the thin plates in the cutting process are shaken by the machining fluid and cracked.

[0041] The workpiece W is sandwiched between the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b and fixed inside the thin plate machining stabilizing unit 70. That is, the workpiece W is sandwiched between the facing surface 71as of the machining fluid flow rectifying plate 71a and the facing surface 71bs of the machining fluid flow rectifying plate 71b and fixed to the facing surface 71as of the machining fluid flow rectifying plate 71a. With an axial direction of the columnar shape of the workpiece W perpendicular to the facing surface 71as of the machining fluid flow rectifying plate 71a and the facing surface 71bs of the machining fluid flow rectifying plate 71b, one end surface of the columnar shape of the workpiece W is fixed to the facing surface 71as of the machining fluid flow rectifying plate 71a.Another end surface of the columnar shape of the workpiece W is in close contact with the facing surface 71bs of the machining fluid flow rectifying plate 71b.

[0042] In a case where the workpiece W is a material for a semiconductor wafer, the shape of the workpiece W is often formed into a columnar shape in advance so that thin plates become circular thin plates after cutting. Here, with respect to the workpiece W having a columnar shape, a side surface of the column forming a curved surface is referred to as an outer peripheral side surface. The workpiece W is arranged in the thin plate processing stabilizing unit 70 so that the outer peripheral side surface faces the cutting wire parts 1b. When the workpiece W is cut by the cutting wire parts 1b, wafers, which are thin plates, are processed from the workpiece W.

[0043] In an electrical discharge cutting step in which the workpiece W is cut by the cutting wire parts 1b, a portion of the workpiece W where cutting by the cutting wire parts 1b begins is defined as a cutting start portion. In the electrical discharge cutting step in which the workpiece W is cut by the cutting wire parts 1b, a portion of the workpiece W where cutting by the cutting wire parts 1b is completed is defined as a machining end portion.

[0044] The cutting wire pieces 1b are repeatedly wound at predetermined intervals and extend between the machining fluid flow rectifying plate 71b and the machining fluid flow rectifying plate 71a facing each other in parallel, with the workpiece W being fixed to the machining fluid flow rectifying plate 71a arranged therebetween.

[0045] When the machining fluid flow rectifying plate 71a to which the workpiece W is fixed and the machining fluid flow rectifying plate 71b are installed in a position changing mechanism (not illustrated) that changes and fixes positions of the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b so as to be rotated or inclined relative to the cutting wire parts 1b, and machining is performed, a plurality of thin plates can be cut out from the workpiece W at the same time, the plurality of thin plates each having a cut surface that, when the facing surface 71as of the machining fluid flow rectifying plate 71a is used as a reference surface, forms a specific angle with respect to the reference surface.A rotary table and a tilting table can be used as a mechanism for rotating or tilting the workpiece W.

[0046] As in Fig. As illustrated in Figure 3, the workpiece power supply support portion 73 is in contact with the outer peripheral side surface of the workpiece W and is fixed to the machining fluid flow rectifying plate 71a at a machining end portion of the workpiece W. In a region of the workpiece W from a diameter portion to the cutting start portion, the workpiece receiving unit 72 is in contact with the outer peripheral side surface of the workpiece W and is fixed to the machining fluid flow rectifying plate 71a. Fig. 3, the workpiece holding unit 72 is installed along the cut outer peripheral side surface of the workpiece W.

[0047] The diameter portion is a portion of the workpiece W at which a maximum cutting length is obtained, wherein the workpiece W has a columnar shape and a cutting length thereof varies according to a cutting position of the workpiece W in the z-axis direction. The cutting length during cutting of the workpiece W is the cutting length by the cutting wire parts 1b during cutting in the horizontal direction, that is, the y-axis direction.

[0048] The workpiece power supply support portion 73 comes into contact with the outer peripheral side surface of the workpiece W from below the workpiece W to hold and fix the workpiece W. Moreover, the workpiece power supply support portion 73 forms a power supply path from the machining fluid flow rectifying plate 71a to the workpiece W. The workpiece power supply support portion 73 is fixed to the machining fluid flow rectifying plate 71a, with the outer peripheral side surface of the workpiece power supply support portion 73 in contact with the outer peripheral side surface of a lowermost portion of the workpiece W.That is, the workpiece power supply support portion 73 is in contact with the outer peripheral side surface of the machining end portion, that is, a portion where the cutting of the workpiece W by the cutting wire parts 1b is completed, and is fixed to the machining fluid flow rectifying plate 71a.

[0049] The workpiece power supply support portion 73 has, for example, a columnar shape. Regarding the workpiece power supply support portion 73 having a columnar shape, an axial direction of the columnar shape is perpendicular to the facing surface 71as of the machining fluid flow rectifying plate 71a, one end surface of the columnar shape is fixed to the facing surface 71as of the machining fluid flow rectifying plate 71a. The height of the workpiece power supply support portion 73 from the facing surface 71a, which is an installation surface thereof on the machining fluid flow rectifying plate 71a, is set to be less than or equal to the thickness of the workpiece W. The thickness of the workpiece W is the length of the workpiece W in the axial direction of the columnar shape.The shape of the workpiece power supply support portion 73 is not limited to the columnar shape.

[0050] Such a workpiece power supply support portion 73 may be referred to as a lower workpiece holding portion which has conductivity and which comes into contact with the workpiece W from below to hold the workpiece W.

[0051] The thin plate side surface holding portions 75a and 75b come into contact with the outer peripheral side surface of the workpiece W from below the workpiece W to hold and fix the workpiece W. Moreover, the thin plate side surface holding portions 75a and 75b form a power supply path from the machining fluid flow rectifying plate 71a to the workpiece W. The thin plate side surface holding portions 75a and 75b are arranged on the facing surface 71as of the machining fluid flow rectifying plate 71a at positions below the diameter portion of the workpiece W having a columnar shape, the positions being symmetrical with respect to the workpiece power supply assisting portion 73 and being located above the position where the cutting of the workpiece W is completed and in contact with the outer peripheral side surface of the workpiece W.

[0052] The thin plate side surface holding portions 75a and 75b each have a columnar shape, for example. Regarding the thin plate side surface holding portions 75a and 75b each having a columnar shape, with an axial direction of each columnar shape perpendicular to the facing surface 71as of the machining fluid flow rectifying plate 71a, one end surface of the columnar shape is fixed to the facing surface 71as of the machining fluid flow rectifying plate 71a. The height of the thin plate side surface holding portions 75a and 75b from the facing surface 71a, which is the installation surface thereof on the machining fluid flow rectifying plate 71a, is set to be less than or equal to the thickness of the workpiece W. The thickness of the workpiece W is the length of the workpiece W in the axial direction of the columnar shape.The shape of the thin plate side surface holding portions 75a and 75b is not limited to the columnar shape.

[0053] Such side surface thin plate holding portions 75a and 75b may each be referred to as a lower workpiece holding portion that has conductivity and comes into contact with the workpiece W from below to hold the workpiece W. The side surface thin plate holding portions 75a and 75b are cut together with the workpiece W as described later, and a plurality of thin plate portions of the side surface thin plate holding portions 75a and 75b formed by cutting the side surface thin plate holding portions 75a and 75b support and fix the plurality of thin plates formed by cutting from the workpiece W simultaneously with the thin plate portions and separated from each other.

[0054] The workpiece receiving unit 72 receives the plurality of thin plates in the cutting process from an outer peripheral side surface side to a cutting start portion side of the plurality of thin plates and collectively fixes the plurality of thin plates in the cutting process. By collectively fixing the plurality of thin plates in the cutting process, the workpiece receiving unit 72 can reduce shaking of the plurality of thin plates due to vibration of the workpiece W generated by fluid pressure of the machining fluid flow absorbed by cutting surfaces of the plurality of thin plates. The workpiece receiving unit 72 has a rectangular parallelepiped shape in which a groove portion 72a is formed, which receives a part of the workpiece W on the cutting start portion side. The shape of the workpiece receiving unit 72 is not limited to the rectangular parallelepiped shape.

[0055] The workpiece holding unit 72 is not installed at a time when the electrical discharge cutting of the workpiece W starts. Regarding the workpiece holding unit 72, at a time when the electrical discharge cutting takes place after the electrical discharge cutting of the workpiece W starts and the electrical discharge cutting progresses by the cutting wire parts 1b to a position corresponding to approximately 1 / 6 or more and 1 / 5 or less of a cutting pitch of the workpiece W, a contact portion of the workpiece holding unit 72 from above the workpiece W and the plurality of thin plates is pressed against upper portions of the workpiece W and each thin plate in the middle of machining. The workpiece holding unit 72 is inserted into a space enclosed between the pair of machining fluid flow rectifying plates 71a and 71b from above the workpiece W and each thin plate.The workpiece receiving unit 72 is automatically arranged by the workpiece receiving unit holding device 78 at the upper portions of the plurality of thin plates in the cutting process.

[0056] The cutting distance is a distance from the cutting start portion to the machining end portion of the workpiece W and corresponds to the diameter of the workpiece W.

[0057] The workpiece receiving unit holding device 78 automatically arranges the workpiece receiving unit 72 at the upper portions of the plurality of thin plates in the cutting process at a predetermined timing according to the control of the control unit 300. Furthermore, the workpiece receiving unit holding device 78 retracts the workpiece receiving unit 72 from the upper portions of the plurality of thin plates after cutting at a time when the cutting of the workpiece W is completed according to the control of the control unit 300. The position of the workpiece receiving unit 72 in the height direction is maintained by the workpiece receiving unit holding device 78. The workpiece receiving unit 72 is held in an initial cutting position that is upwardly separated from the workpiece W and the cutting wire parts 1b at the start of cutting.After cutting starts, the workpiece holding unit 72 fixes thin plates, which are machined into a thin plate shape from the workpiece W. A force for pressing the workpiece holding unit 72 against the thin plates is obtained using a driving device such as a motor or an air cylinder, or a weight.

[0058] The contact portion of the workpiece receiving unit 72 is a portion where the workpiece receiving unit 72 contacts the upper portion of the workpiece W, that is, the upper portions of the plurality of thin plates. The contact portion of the workpiece receiving unit 72 is formed in a shape that follows the outer peripheral side surface of the workpiece W, that is, a shape that follows the outer peripheral side surfaces of the plurality of thin plates. That is, in a case where the shape of the workpiece W has a columnar shape, the contact portion of the workpiece receiving unit 72 is formed in an arc shape, which is a shape that follows the outer peripheral side surface of the columnar shape.

[0059] Furthermore, a thin plate section holder 76 is attached to the contact portion of the workpiece holding unit 72. The thin plate section holder 76 holds the workpiece W from above to collectively fix the plurality of thin plates in the cutting process. That is, the thin plate section holder 76 receives the plurality of thin plates in the cutting process from the outer peripheral side surface side on the cutting start portion side of the plurality of thin plates and collectively fixes the plurality of thin plates in the cutting process. The thin plate section holder 76 increases a contact area between the contact portion of the workpiece holding unit 72 and the workpiece W, that is, a contact area between the contact portion of the workpiece holding unit 72 and the outer peripheral side surfaces of the plurality of thin plates, and collectively fixes the plurality of thin plates in the cutting process.By collectively fixing the plurality of thin plates in the cutting process, the thin plate portion holder 76 increases the contact area between the contact portion of the workpiece holding unit 72 and the outer peripheral side surfaces of the plurality of thin plates and reduces shaking of the plurality of thin plates due to vibration of the workpiece W generated by a fluid pressure of the machining fluid flow received by the cutting surfaces of the plurality of thin plates.

[0060] When the workpiece holding unit 72 is pressed against the outer peripheral side surface of the workpiece W, that is, the outer peripheral side surfaces of the plurality of thin plates, the thin plate section holder 76 is deformed between the contact portion of the workpiece holding unit 72 and the outer peripheral side surface of the workpiece W. A portion of the deformed thin plate section holder 76 enters the interior of a plurality of machined grooves formed between the plurality of thin plates. Consequently, in the wire electrical discharge machining apparatus 1000, the deformed thin plate section holder 76 maintains clearances between the plurality of thin plates cut from the workpiece W, thereby reducing the risk of the thin plates being shaken and cracked by the machining fluid during the cutting process.

[0061] Furthermore, another part of the deformed thin plate section holder 76 does not enter the machined grooves, but fills unevenness of the contact portion of the workpiece holding unit 72 and unevenness of the outer peripheral side surface of each thin plate, and is sandwiched between the contact portion of the workpiece holding unit 72 and the outer peripheral side surface of each thin plate. Consequently, in the wire electrical discharge machining apparatus 1000, the contact area between the contact portion of the workpiece holding unit 72 and the outer peripheral side surface of each thin plate is increased via the thin plate section holder 76, thereby increasing the force for holding, from above the workpiece W, the outer peripheral side surfaces of the plurality of thin plates to be cut out from the workpiece W in the cutting process.

[0062] Therefore, when the workpiece holding unit 72 is pressed against the outer peripheral side surface of the workpiece W, that is, the outer peripheral side surfaces of the plurality of thin plates, the thin plate section holder 76 is deformed, holds the plurality of thin plates in the cutting process from the thickness direction of the thin plates, and holds the outer peripheral side surfaces of the plurality of thin plates in the cutting process from above the workpiece W, thereby reducing shaking and cracking of the thin plates in the cutting process caused by the machining fluid.

[0063] A conductive adhesive, a conductive sheet, a conductive adhesive tape, a low-melting-point metal, a conductive wax, or the like having conductive properties is used to fix the workpiece W to the machining fluid flow rectifying plate 71a. Using a conductive material to fix the workpiece W to the machining fluid flow rectifying plate 71a enables conduction between the workpiece W and the machining fluid flow rectifying plate 71a. Consequently, as described later, the electrical discharge machining power can be supplied to the workpiece W from the machining power supply 5 via the machining fluid flow rectifying plate 71a.

[0064] In addition to the conductive adhesive, the conductive sheet material, the conductive adhesive tape, the low-melting-point metal, and the conductive wax with conductivity, a screw connection using a metal screw is used to fix the workpiece power supply support portion 73 and the thin-plate side-surface holding portions 75a and 75b to the machining fluid flow rectifying plate 71a. Using a conductive material to fix the workpiece power supply support portion 73 and the thin-plate side-surface holding portions 75a and 75b to the machining fluid flow rectifying plate 71a enables conduction between the machining fluid flow rectifying plate 71a and each of the workpiece power supply support portion 73 and the thin-plate side-surface holding portions 75a and 75b.Consequently, as described later, the electrical discharge machining power can be supplied to the workpiece W via the machining fluid flow rectifying plate 71a and the workpiece power supply supporting portion 73 from the machining power supply 5. Furthermore, the electrical discharge machining power can be supplied from the machining power supply 5 to the workpiece W via the machining fluid flow rectifying plate 71a and the thin plate side surface holding portions 75a and 75b.

[0065] Fig. 4 is a diagram illustrating a supply path of an electrical discharge machining power supply from the machining power supply 5 to the workpiece W in the wire machining apparatus 1000 according to the first embodiment. In the wire electrical discharge machining apparatus 1000, the electrical discharge machining power is supplied to the workpiece W via the machining fluid flow rectifying plate 71a from the machining power supply 5. The electrical discharge machining power is also supplied to the workpiece W via the machining fluid flow rectifying plate 71a and the workpiece power supply supporting section 73 from the machining power supply 5. The electrical discharge machining power is also supplied to the workpiece W via the machining fluid flow rectifying plate 71a and the thin plate side surface holding section 75a from the machining power supply 5.The electrical discharge machining power is also supplied to the workpiece W via the machining fluid flow rectifying plate 71a and the thin plate side surface holding portion 75b from the machining power supply 5.

[0066] The control unit 300 controls the entirety of the wire electrical discharge machining apparatus 1000. Fig. 5 is a block diagram illustrating an exemplary configuration of the control unit 300 included in the wire discharge machining apparatus 1000 according to the first embodiment. The control unit 300 includes a machining controller 31, an electric discharge waveform controller 32, a machining state detection unit 33, a cutting table drive controller 34, a wire travel controller 35, and a workpiece support unit holding controller 36. The control unit 300 controls the wire discharge machining apparatus 1000.

[0067] The machining state detection unit 33 detects various types of machining state information ps, including the position of the workpiece W in the z-axis direction, from outputs of various sensors, and outputs the detected machining state information ps to the machining controller 31. The machining controller 31 controls the electric discharge waveform controller 32, the cutting table drive controller 34, and the wire travel controller 35 based on the detected machining state information ps. The electric discharge waveform controller 32 controls the machining power supply 5 based on an electric discharge waveform command wc input from the machining controller 31, and controls a waveform of a voltage applied between electrodes or a waveform of a current flowing between the electrodes.

[0068] The wire running control device 35 drives and controls the coil rotation control devices 8a and 8b based on a wire electrode running command rc input from the machining control device 31 and controls the running of the wire electrode 1. In addition, the wire running control device 35 drives and controls the transverse control devices 9a and 9b based on the wire electrode running command rc input from the machining control device 31.

[0069] The cutting table drive controller 34 drives the cutting feed table 10 based on a table command sc input from the machining controller 31 and controls the relative positions of the workpiece W and the cutting wire parts 1b. Furthermore, the cutting table drive controller 34 also sends the table command sc to the workpiece receiving unit holding controller 36 connected to the workpiece receiving unit holding device 78.

[0070] The workpiece support unit holding controller 36 monitors a coordinate value of the cutting feed table 10 in the z-axis direction based on the table command sc from the cutting table drive controller 34, drives and controls the workpiece support unit holding device 78 based on a holding control command qc simultaneously with the cutting feed table 10 reaching a preset first position, and controls the arrangement of the workpiece support unit 72 on upper portions of the plurality of thin plates in the cutting process.Furthermore, the workpiece receiving unit holding controller 36 monitors the coordinate value of the cutting feed table 10 in the z-axis direction based on the table command sc from the cutting table drive controller 34, drives and controls the workpiece receiving unit holding device 78 based on the holding control command qc simultaneously with the cutting feed table 10 reaching a preset second position, and performs control to retract the workpiece receiving unit 72 from the upper portions of the plurality of thin plates after cutting.

[0071] Fig. 6 is a flowchart illustrating an operation of the wire electric discharge machining apparatus 1000 according to the first embodiment during cutting. Fig. 7 is a first perspective view illustrating a state of thin plates during cutting in the thin plate machining stabilizing unit 70 included in the wire electric discharge machining apparatus 1000 according to the first embodiment. Fig. 8 is a second perspective view illustrating the state of the thin plates during cutting in the thin plate machining stabilizing unit 70 included in the wire electric discharge machining apparatus 1000 according to the first embodiment.

[0072] Fig. 7 illustrates a state in which the workpiece W is cut at a position corresponding to about 1 / 6 from the outer peripheral side surface of the workpiece W on the cutting start portion side, that is, from the outer peripheral side surface of the workpiece W on the upper side thereof in the height direction. Fig. 8 illustrates a state in which the cutting is further from that in Fig. 7, wherein the workpiece holding unit 72 is in contact with the outer peripheral side surface of the workpiece W on the side of the cutting start portion, that is, the outer peripheral side surfaces of the plurality of thin plates on the upper side thereof, and the plurality of thin plates are held by the workpiece holding unit 72 in the cutting process. Fig. 8 illustrates a state in which the cutting wire parts 1b exceed a center axis C of the workpiece W in a downward direction in the z-axis direction, and the thin plate side surface holding portions 75a and 75b, which are fixed in contact with the outer peripheral side surface of the workpiece W, are also cut simultaneously with the workpiece W by the cutting wire parts 1b. Fig. For ease of understanding, Fig. 7 is a perspective view showing the state of some components of the wire discharge machining apparatus 1000. The following describes the operation of the wire discharge machining apparatus 1000 during cutting. Note that the following operation is performed under the control of the control unit 300.

[0073] At the start of cutting, the workpiece W is installed and fixed in the thin plate machining stabilizing unit 70. At the start of cutting, the workpiece W is separated from the cutting wire parts 1b and is located just below the cutting wire parts 1b. Moreover, the workpiece holding unit 72 is not installed at the start of cutting. In this state, the cutting wire parts 1b begin to travel. The cutting wire parts 1b pass through the plurality of machining fluid ejection holes 7c of the nozzles 7a and 7b and pass just above the workpiece W sandwiched between the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b.

[0074] The electrical discharge machining power is supplied to the workpiece W from the machining power supply 5 via the machining fluid flow rectifying plate 71a. The electrical discharge machining power supply from the machining power supply 5 to the workpiece W is performed by the machining fluid flow rectifying plate 71a via each of the workpiece power supply support section 73, the thin plate side surface holding section 75a, and the thin plate side surface holding section 75b. The electrical discharge machining power is supplied to the cutting wire parts 1b via the power supply contact units 6a and 6b from the machining power supply 5. The machining fluid is supplied from the nozzles 7a and 7b to a gap between the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b.

[0075] When cutting begins, the control unit 300 raises the cutting feed table 10 to change the relative positions of the workpiece W and the cutting wire parts 1b. Specifically, the control unit 300 raises the cutting feed table 10, thereby moving the thin plate machining stabilizing unit 70, in which the workpiece W is installed and fixed, upward. Consequently, the workpiece W installed in the thin plate machining stabilizing unit 70 relatively approaches and comes into contact with the cutting wire parts 1b, and is cut by the cutting wire parts 1b.

[0076] When cutting begins, a machining fluid flow rectification step is performed in step S110. In the machining fluid flow rectification step, the flow of the machining fluid supplied from the nozzles 7a and 7b of the thin plate machining stabilizing unit 70 is rectified so that the machining fluid impacts the workpiece W. In the thin plate machining stabilizing unit 70, with respect to the machining fluid supplied from the nozzles 7a and 7b to the thin plate machining stabilizing unit 70, its flow in the x-axis direction is restricted by the machining fluid flow rectification plate 71a and the machining fluid flow rectification plate 71b, and the machining fluid impacts the workpiece W.That is, the facing surface 71as of the machining fluid flow rectifying plate 71a and the facing surface 71bs of the machining fluid flow rectifying plate 71b regulate a movement of the flow of the machining fluid supplied to the gap between the machining fluid flow rectifying plate 71a and the machining fluid flow rectifying plate 71b in the x-axis direction, which is the central axis direction of the workpiece W, and form a flow path that guides the flow of the machining fluid to the workpiece W.

[0077] Therefore, it can be said that the machining fluid flow rectifying step is a step of ejecting the machining fluid from the nozzles 7a and 7b toward the space enclosed between the pair of machining fluid flow rectifying plates 71, guiding the flow of the machining fluid toward the workpiece W through the facing surfaces 71as and 71bs of the pair of machining fluid flow rectifying plates 71, and supplying the machining fluid to the gap between the plurality of cutting wire members 1b and the workpiece W.

[0078] As described above, the control unit 300 controls each component of the wire electrical discharge machining apparatus 1000 so that the electrical discharge cutting of the workpiece W proceeds. Note that the machining fluid flow rectification step in step S110 is continuously performed from the start of cutting to the end of cutting.

[0079] Thereafter, a wafer pickup step is performed in step S120. In the wafer pickup step, at a time when the electrical discharge cutting progresses and the electrical discharge cutting by the cutting wire parts 1b advances to a position corresponding to approximately 1 / 6 or more and 1 / 5 or less of the cutting pitch of the workpiece W, the contact portion of the workpiece pickup unit 72 is pressed against upper portions of the workpiece W and each thin plate from above the workpiece W and the plurality of thin plates in the cutting process.

[0080] Consequently, the thin plate section holder 76 attached to the contact portion of the workpiece receiving unit 72 receives the workpiece W from above to collectively fix the plurality of thin plates in the cutting process. That is, the thin plate section holder 76 receives the plurality of thin plates in the cutting process from the outer peripheral side surface side on the cutting start portion side of the plurality of thin plates and collectively fixes the plurality of thin plates in the cutting process. By collectively fixing the plurality of thin plates in the cutting process, the thin plate section holder 76 reduces shaking of the plurality of thin plates due to vibration of the workpiece W generated by fluid pressure of the machining fluid flow received by the cutting surfaces of the plurality of thin plates.

[0081] Then, the electrical discharge cutting of the workpiece W is continued in a state where the plurality of thin plates in the cutting process are collectively fixed by the workpiece holding unit 72, as described above. Here, since the plurality of thin plates to be cut from the workpiece W are held in contact with the outer peripheral side surfaces of the plurality of thin plates by the thin plate side surface holding portions 75a and 75b, the plurality of thin plates are not shaken or deflected by the pressure of the machining fluid supplied from the nozzles 7a and 7b toward the machined grooves Wg, and a change in the gap between adjacent thin plates in the x-axis direction is reduced.As a result, the supply of machining fluid into the machined grooves formed between the adjacent thin plates does not change, the machining residues generated by the electrical discharge cutting are stably discharged from between the electrodes, i.e., the gap between the workpiece W and the cutting wire parts 1b, and the cutting wire parts 1b are stably cooled. Consequently, the wire discharge machining apparatus 1000 can stably continue the wire discharge cutting of the workpiece W.

[0082] Therefore, it can be said that the wafer holding step is a step of holding the workpiece W to be divided during the cutting process from above the workpiece W and the plurality of cutting wire parts 1b.

[0083] Thereafter, a wafer support step is performed in step S130. When the electrical discharge cutting is further continued and the cutting wire parts 1b reach the side surface holding portions 75a and 75b for thin plates in the z-axis direction, as shown in Fig. 8, the side surface holding portions 75a and 75b are subjected to electrical discharge cutting from above by the cutting wire parts 1b simultaneously together with the workpiece W.

[0084] In the wafer supporting step, the workpiece power supply supporting portion 73 and the thin plate side surface holding portions 75a and 75b, which are lower workpiece holding portions having conductivity, come into contact with the workpiece W from below to hold the workpiece W during cutting of the workpiece W. The lower workpiece holding portions are provided over upper and lower regions of the machining end portion, which is the portion where cutting of the workpiece W is completed in a cutting direction of the workpiece W, and are fixed to the facing surface 71a of the machining fluid flow rectifying plate 71a, which is one of the pair of machining fluid flow rectifying plates 71.In this state, from the start of cutting of the workpiece W to the end of cutting of the workpiece W, power is supplied to the workpiece W from the machining fluid flow rectifying plate 71a via the workpiece power supply supporting portion 73 and the thin plate side surface holding portions 75a and 75b, which are lower workpiece holding portions.

[0085] When the electrical discharge cutting proceeds and the cutting wire parts 1b reach the side surface holding portions 75a and 75b for thin plates in the z-axis direction, as shown in Fig. 8, the thin plate side surface holding portions 75a and 75b are subjected to electrical discharge cutting from above by the cutting wire parts 1b simultaneously with the workpiece W. In this state, until the end of cutting of the workpiece W, power is supplied to the workpiece W from the machining fluid flow rectifying plate 71a via the workpiece power supply supporting portion 73 and the thin plate side surface holding portions 75a and 75b, which are lower workpiece holding portions.

[0086] The thin plate side surface holding portions 75a and 75b are installed so that a lowermost portion of each thereof is located below the lowermost portion of the workpiece W. Therefore, a holding force of each of the thin plate side surface holding portions 75a and 75b with respect to the plurality of thin plates to be machined from the workpiece W is not lost because the thin plate side surface holding portions 75a and 75b are cut and separated into the plurality of thin plates in the middle of machining the workpiece W.That is, at a time when the electrical discharge cutting performed on the workpiece W is completed, a plurality of thin plate portions 75c are formed in the side surface thin plate holding portions 75a and 75b, each of the thin plate portions 75c having a width corresponding to that of a thin plate formed from the workpiece W, and the number of thin plate portions 75c being equal to that of thin plates formed from the workpiece W.

[0087] However, the plurality of thin plate portions 75c formed in the side surface thin plate holding portions 75a and 75b are not separated from the workpiece W. Therefore, in a state where the electrical discharge cutting of the plurality of thin plates from the workpiece W is completed, a holding state of the plurality of thin plates machined from the workpiece W is continued by each of the thin plate portions 75c formed on the side surface thin plate holding portions 75a and 75b and the workpiece receiving unit 72.

[0088] Fig. 9 is a set of diagrams for explaining a relationship between the cutting position and the cutting length of the workpiece W during cutting by the wire discharge machining apparatus 1000 according to the first embodiment. The left diagram of Fig. 9 illustrates an example of a positional relationship between the workpiece W, the workpiece power supply support section 73, and the thin plate side surface holding sections 75a and 75b in a co-plane direction of the facing surface 71as of the machining fluid flow rectifying plate 71a. The right-hand illustration from Fig. 9 illustrates a cutting length corresponding to a cutting position of the workpiece W in the left illustration. Fig. 9. A solid line in the right-hand illustration from Fig. 9 indicates a cutting length when cutting the workpiece W by the wire discharge machining device 1000. A dashed line in the right figure from Fig. 9 indicates a cutting length when cutting the workpiece W in a case where the side surface holding portions 75a and 75b for thin plates are not installed in the configuration of the wire discharge machining apparatus 1000. A dashed line in the right-hand diagram from Fig. 9 indicates a cutting length in a case where only the side surface holding portions 75a and 75b for thin plates are cut by the wire electric discharge machining apparatus 1000.

[0089] When cutting the workpiece W having a columnar shape by the wire electric discharge machining apparatus 1000, the cutting length varies according to the cutting position in the height direction during cutting, that is, according to the cutting position in the z-axis direction during cutting.

[0090] As shown by the solid line in the right-hand illustration Fig. 9, when cutting proceeds from an uppermost end portion of the workpiece W, which is a machining start position PS of the workpiece W, toward a lowermost end portion of the workpiece W, which is a machining end position PE of the workpiece W, in a machining section of the workpiece W, the cutting length varies according to the cutting position of the workpiece W in the height direction, and the cutting length is the highest at a diameter section position PD of the workpiece W. As cutting continues further and the cutting wire parts 1b pass through the diameter section position PD of the workpiece W in the height direction, the cutting length decreases as cutting progresses.

[0091] As cutting progresses and the cutting wire parts 1b reach the thin plate side surface holding portions 75a and 75b in the z-axis direction at a machining position PH, the thin plate side surface holding portions 75a and 75b are subjected to cutting from above by the cutting wire parts 1b simultaneously with the workpiece W. From this point on, the cutting length becomes a total cutting length of the cutting length of the workpiece W and the cutting lengths of the thin plate side surface holding portions 75a and 75b, which temporarily increases and then decreases as cutting progresses. That is, in the wire electrical discharge machining apparatus 1000, the thin plate side surface holding portions 75a and 75b are cut together with the workpiece W, so that a rapid decrease in the cutting length near the machining end portion is mitigated.

[0092] As shown by the dashed line in the right-hand illustration Fig. As shown in Figure 9, in the case where the thin plate side surface holding portions 75a and 75b are not arranged in the configuration of the wire discharge machining apparatus 1000, the cutting length decreases in accordance with a change in the cutting position as cutting progresses beyond the machining position PH, and rapidly decreases near the machining end portion. The rapid decrease in the cutting length becomes one of the causes of a sudden change in a wire discharge machining state. When the wire discharge machining state changes suddenly, the risk of wire breakage increases.In addition, when the wire EDM machining condition changes suddenly and if no suitable machining condition is selected for the thin plates for the change of cutting length, a variation in the thickness of machined thin plates in cutting surface planes occurs, which adversely affects the quality of the thin plates.

[0093] On the other hand, in the wire electrical discharge machining apparatus 1000, the thin plate side surface holding portions 75a and 75b arranged to hold the plurality of thin plates are cut together with the workpiece W, and thereby the rapid decrease in the cutting length near the machining end portion is mitigated and it is possible to reduce the occurrence of the adverse effect on the cutting quality of the thin plates due to the sudden change in the electrical discharge machining state, as described above.Furthermore, in the wire electrical discharge machining apparatus 1000, the side surface holding portions 75a and 75b are provided for thin plates, and thus a situation in which the machining fluid flow supplied from the nozzles 7a and 7b directly impacts the thin plates is alleviated, so that shaking of the thin plates by the machining fluid flow is reduced and occurrence of cracking of the thin plates or chipping of the thin plates, which is likely to occur at the machining end portion of the thin plate, is prevented.

[0094] Next, the arrangement positions of the thin plate side surface holding portions 75a and 75b with respect to the workpiece W and the size of the thin plate side surface holding portions 75a and 75b will be described. The thin plate side surface holding portions 75a and 75b are fixed to the machining fluid flow rectifying plate 71a in a state where the outer peripheral side surfaces of the thin plate side surface holding portions 75a and 75b are in contact with the outer peripheral side surface of the workpiece W.Contact positions of the outer peripheral side surfaces of the thin plate side surface holding portions 75a and 75b with respect to the outer peripheral side surface of the workpiece W are each located in a partial region where an uncut length in the cutting direction of the workpiece W is 1 / 2 or less of the total cutting length of the workpiece W in the height direction, that is, in the cutting direction of the workpiece W, the partial region also being located above a position where the outer peripheral side surface of the workpiece power supply assisting portion 73 is in contact with the outer peripheral side surface of the workpiece W, that is, the partial region also being located above a position where cutting of the workpiece W is completed.

[0095] The uncut length in the cutting direction is the length of the area where the workpiece W has not yet been cut in the cutting direction, which is a downward direction, i.e., a Z-axis downward direction. The cutting length of the entire workpiece W is the length of the diameter of the workpiece W, which has a columnar shape.

[0096] The width of the thin plate side surface holding portions 75a and 75b is set to a length by which the outer peripheral side surfaces of the thin plate side surface holding portions 75a and 75b in contact with the outer peripheral side surface of the workpiece W do not protrude from the machining fluid flow rectifying plates 71a and 71b. The width of the thin plate side surface holding portions 75a and 75b is a maximum length of the thin plate side surface holding portions 75a and 75b in the y-axis direction, that is, the maximum length of the thin plate side surface holding portions 75a and 75b in the traveling direction of the cutting wire parts 1b with respect to the workpiece W. In a state where the workpiece W has been completely cut and the cutting wire parts 1b have passed the entirety of the workpiece W, a remaining machining portion is located in each of the thin plate side surface holding portions 75a and 75b.

[0097] As described above, the thin plate side surface holding portions 75a and 75b are formed with a conductive material to implement a power supply function to the workpiece W. On the other hand, even with such a conductive material, for example, in a case where there is a significant difference in a physical property value such as an electrical resistance value or a thermal conductivity between the conductive material and a material of the workpiece W, a difference in the electrical discharge machining characteristics arises, such as a difference in a machining speed due to a difference in the probability of arc discharge occurrence or a difference in the degree of damage to the wire electrode 1 due to a difference in wear characteristics of the wire electrode 1.As a result, it can be considered that in a region where the workpiece W and the side surface holding portions 75a and 75b for thin plates are cut simultaneously, the influence of the difference in the electrical discharge machining characteristics on the cutting becomes significant, thereby destabilizing the electrical discharge machining.

[0098] Therefore, the material for the thin plate side surface holding portions 75a and 75b is preferably the same conductive material as that for the workpiece W, which can achieve the same electrical discharge machining characteristics as those of the workpiece W. For example, in a case where the workpiece W made of SiC is cut, the thin plate side surface holding portions 75a and 75b made by machining a sintered body made of SiC powder can be used.

[0099] When the cutting of the workpiece W having a columnar shape approaches the vicinity of the machining end portion of the workpiece W and approaches a state where the plurality of thin plates are cut and separated from the workpiece W, the flow rate of the machining fluid supplied from the nozzles 7a and 7b is adjusted to a flow rate that does not cause breakage of portions of the wire electrode 1 corresponding to the cutting wire parts 1b. Consequently, an external force that shakes the plurality of thin plates in the cutting process, that is, the fluid pressure of the machining fluid flow received by the cutting surfaces of the plurality of thin plates, is reduced.In this state, the cutting wire parts 1b pass the workpiece W while cutting continues, reach the workpiece power supply support section 73, and start cutting the workpiece power supply support section 73 made of a material similar to that of the workpiece W. Thereafter, the cutting is stopped when the control unit 300 determines that the cutting to the thin plates is completely completed based on the degree of progress of the cutting wire parts 1b in the cutting direction.

[0100] When the workpiece W is separated into the plurality of thin plates, depending on a separation state of the thin plates from the workpiece W, a supply path for electrical discharge machining power from the machining fluid flow rectifying plate 71a to the workpiece W may be interrupted. The workpiece power supply support section 73 and the thin plate side surface holding sections 75a and 75b form a supply path for electrical discharge machining power to the workpiece W and the plurality of thin plates in the cutting process from the start of cutting to the completion of cutting. Consequently, the wire electrical discharge machining apparatus 1000 can stably continue the wire cutting of the workpiece W.

[0101] When a supply path for electrical discharge machining power to the cutting wire parts 1b is interrupted just before cutting is completed, cutting is suspended, resulting in a thin plate that is not completely separated due to a remaining machining portion that has not been cut yet, or a thin plate that cracks at a boundary between the remaining machining portion and the already cut portion. Furthermore, machining between the electrodes, which is a machining gap for electrical discharge machining in the cutting direction, easily precedes a tip of each cutting wire part 1b. Therefore, the thin plates are cut and separated before the cutting wire parts 1b completely pass through the workpiece W.As a result, remaining machining portions remain as tiny residual protrusions at the machining end portions of the separated thin plates, thereby reducing the cutting quality and yield of the thin plates.

[0102] On the other hand, the workpiece power supply support portion 73 is in contact with the workpiece W and is fixed at a position in contact with the lowermost end portion of the workpiece W, and thus can hold the plurality of thin plates together with the workpiece receiving unit 72 and the thin plate side surface holding portions 75a and 75b against the external force that shakes the plurality of thin plates just before they are separated, and can prevent the occurrence of cracking and chipping of the thin plates.

[0103] The workpiece power supply support section 73 and the thin plate side surface holding sections 75a and 75b form the supply path for electrical discharge machining power to the workpiece W and the plurality of thin plates in the cutting process from the start of cutting to the completion of cutting. Consequently, the wire electrical discharge machining apparatus 1000 can stably continue wire cutting of the workpiece W.Therefore, in the wire electrical discharge machining apparatus 1000, the supply path of electrical discharge machining power from the machining fluid flow rectifying plate 71a to the workpiece W is not interrupted depending on a separation state of the thin plates from the workpiece W, and it is possible to prevent the occurrence of a residual protrusion caused by the cutting wire parts 1b not completely passing through the workpiece W due to the interruption of the supply path of electrical discharge machining power from the machining fluid flow rectifying plate 71a to the workpiece W.

[0104] As described above, the wire electrical discharge machining apparatus 1000 according to the first embodiment implements a wire electrical discharge machining apparatus that generates an electric discharge between a plurality of cutting wire parts that revolve and a workpiece to perform electrical discharge machining on the workpiece with energy generated by the electric discharge, and simultaneously cuts a plurality of wafers from the workpiece, the wire electrical discharge machining apparatus including: a wire electrode including the plurality of cutting wire parts that are spaced apart in parallel from each other and face the workpiece; a power supply unit that generates an electric discharge between the plurality of cutting wire parts and the workpiece;a pair of machining fluid flow rectifying plates having conductivity, connected to a power supply, and provided in contact with both sides of the workpiece to enclose the workpiece; a pair of nozzles into which the plurality of cutting wire members are inserted, the pair of nozzles including a plurality of machining fluid ejection holes that eject a machining fluid toward a space enclosed between the pair of machining fluid flow rectifying plates to supply the machining fluid to a gap between the plurality of cutting wire members and the workpiece; a cutting feed table that moves the pair of machining fluid flow rectifying plates up and down relative to the plurality of cutting wire members;a workpiece holding unit that holds the workpiece to be cut from above the workpiece and the plurality of cutting wire pieces during cutting; and a lower workpiece holding portion that has conductivity and comes into contact with the workpiece from below to hold the workpiece.

[0105] As described above, the wire electrical discharge machining apparatus 1000 according to the first embodiment has a structure in which the plurality of thin plates to be cut and separated from the workpiece W by a cutting process are held from the outer peripheral surface side of the workpiece W by the workpiece power supply support section 73, the thin plate side surface holding sections 75a and 75b, and the workpiece support unit 72.Consequently, in the wire electrical discharge machining apparatus 1000, it is possible to reduce or prevent shaking of the thin plates by the flow of the machining fluid supplied from the nozzles 7a and 7b, and to prevent the occurrence of cracking of the thin plates and chipping of the thin plates, which are likely to occur at the machining end portions of the thin plates just before the completion of cutting, and to prevent the occurrence of residual protrusions at the machining end portions of the thin plates due to incomplete cutting of the machining end portion of the workpiece W at the end of cutting.

[0106] Moreover, since the wire electrical discharge machining apparatus 1000 has the above structure, it is not necessary to greatly reduce the flow rate of the machining fluid to reduce the external force on the thin plates due to the impact of the machining fluid flow on the thin plates as the end of cutting approaches, and the discharge of the machining residues from between the electrodes and the cooling state of the cutting wire parts 1b close to between the electrodes are not affected.Consequently, the wire electrical discharge machining apparatus 1000 can prevent a decrease in machining speed due to improper discharge of machining residues or insufficient cooling of the cutting wire parts 1b, and can prevent a risk to the wire electrode 1 due to a sudden change in the wire electrical discharge machining state caused by a significant decrease in the flow rate of the machining fluid.

[0107] Therefore, the wire electric discharge machining apparatus 1000 according to the first embodiment achieves an effect that it is possible to prevent damage to thin plates when the thin plates are cut.

[0108] Second embodiment. Fig. 10 is a schematic view illustrating an exemplary configuration of the workpiece power supply support section 73 included in a wire electric discharge machining apparatus 1000a according to a second embodiment. Fig. 10 illustrates a state in which, in the cutting of the workpiece W into thin plates performed by the wire discharge machining apparatus 1000a, the cutting wire parts 1b pass through the workpiece W and the cutting of the workpiece W into the thin plates is completed and the workpiece W is separated into the plurality of thin plates. In Fig. 10, a conductive connecting part 77 is provided between the workpiece W and the workpiece power supply supporting section 73.

[0109] The wire electrical discharge machining apparatus 1000a according to the second embodiment includes a thin plate machining stabilizing unit 70a instead of the thin plate machining stabilizing unit 70, which is different from the wire electrical discharge machining apparatus 1000 according to the first embodiment. The thin plate machining stabilizing unit 70a includes the conductive connecting part 77, which is different from the thin plate machining stabilizing unit 70 according to the first embodiment. The remaining configuration of the wire electrical discharge machining apparatus 1000a according to the second embodiment is similar to that of the wire electrical discharge machining apparatus 1000 according to the first embodiment, and redundant description will not be repeated.

[0110] In the Fig. In the state illustrated in Figure 10, a plurality of machined grooves 75g are also formed in the thin plate side surface holding portions 75a and 75b by the cutting wire parts 1b. However, the thin plate side surface holding portions 75a and 75b are not separated into a plurality of thin plates. The plurality of thin plates machined from the workpiece W are held by the outer peripheral side surfaces of the thin plate portions 75c formed in the thin plate side surface holding portions 75a and 75b and the workpiece holding unit 72. Fig. 10, the workpiece holding unit 72 is not illustrated.

[0111] As in Fig. As illustrated in FIG. 10, in the wire electrical discharge machining apparatus 1000a, the conductive connecting part 77 is interposed between the workpiece W and the workpiece power supply support section 73. Cutting continues even after the workpiece W is completely cut, and thereby the conductive connecting part 77 is cut by the cutting wire parts 1b that have passed through the workpiece W, and machined grooves 77g are formed. While simultaneously cutting the plurality of thin plates by the cutting wire parts 1b, the control unit 300 determines that the cutting of the thin plates has been completed when the machined grooves 77g are formed in the conductive connecting part 77 by all the portions of the wire electrode 1 constituting the cutting wire parts 1b, and the machining thus ends.

[0112] In a case where the workpiece W is formed of SiC and the conductive connecting part 77 is formed of porous metal, there is a significant difference between the SiC and the porous metal in a situation of generation of a discharge pulse or a short-circuit pulse generated between electrodes, and an oscillation frequency of the discharge pulse generated between the electrodes or the machining speed. Therefore, determining whether cutting into the thin plates is completed can be performed, for example, by detecting a situation of generation of the discharge pulse with which the cutting state suddenly changes.

[0113] The conductive connecting part 77 has flexibility, is arranged to be sandwiched between the workpiece power supply support portion 73 and the workpiece W, and electrically connects the workpiece power supply support portion 73 and the workpiece W. The conductive connecting part 77 fills a gap between the workpiece power supply support portion 73 and the workpiece W, thereby increasing a contact area between outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W facing each other and improving conductivity between the workpiece power supply support portion 73 and the workpiece W.

[0114] For the conductive connecting part 77, a conductive material having flexibility and easy deformability, such as a low-melting-point metal or a porous metal, is used. Due to the easy deformability of the conductive connecting part 77, the conductive connecting part 77, which is pressed against the two outer peripheral side surfaces, that is, the outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply support portion 73, is deformed. Then, the gap between the outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply support portion 73 is filled with the deformed conductive connecting part 77.Therefore, in the wire electric discharge machining apparatus 1000a, the contact area between the outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W facing each other can be increased. Then, by increasing the contact area between the outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W facing each other, the conductivity between the workpiece power supply support portion 73 and the workpiece W is improved.

[0115] As the conductive connecting part 77 to be used, it is only required that it be made of a conductive material having a Young's modulus of 80 Gpa or less and an electrical resistivity of about 10 Ω cm or less, and being deformable enough to fill a minute gap between the workpiece W and the workpiece power supply support portion 73 by pressurization. An example of the dimension of the minute gap is about 100 μm or more and 300 μm or less. As an example, a porous sheet in which metal such as nickel or cobalt is formed in the shape of a mesh is deformable by bending or deformable in a compression direction due to the flexibility of the porous portion.

[0116] Rubber or silicone rubber formed to contain powder of a conductive substance such as silver or carbon and having a specific electrical resistance of 10 Ω cm or less is also deformable by bending or deformable in the compression direction.

[0117] With respect to an adhesive tape obtained by casting a conductive metal foil such as aluminum foil or copper foil, it is difficult to achieve a sufficient degree of deformation by the adhesive tape itself. However, by forming a laminate in which a plurality of sheets of aluminum foil or copper foil are laminated, for example, to a thickness of about 1 mm, the laminate can be used as the conductive connecting part 77.

[0118] A conductive wax kneaded with carbon powder can also be used as the conductive connecting part 77. Since the conductive wax kneaded with the carbon powder has good formability, when the conductive wax is inserted between contact surfaces of the workpiece W and the workpiece power supply support portion 73 and rubbed against the contact surfaces, a tiny gap between the workpiece W and the workpiece power supply support portion 73 can be filled. The conductive wax melts at a temperature of approximately 40°C or more and 60°C or less. Therefore, the conductive wax can be used by pouring it in a molten state into the tiny gap between the workpiece W and the workpiece power supply support portion 73.

[0119] Preferably, the outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply support portion 73 are fully in contact with each other. However, in reality, it is difficult to install the workpiece W and the workpiece power supply support portion 73 on the machining fluid flow rectifying plate 71 in a state where the outer peripheral side surface of the workpiece power supply support portion 73 is fully in contact with the outer peripheral side surface of the workpiece W.That is, in order for the outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply support portion 73 to fully contact each other, it is necessary that the parallelism between the outer peripheral side surfaces of the workpiece W and the workpiece power supply support portion 73 in contact with each other fully coincide, and the workpiece W and the workpiece power supply support portion 73 are installed on the machining fluid flow rectifying plate 71a in a state where the workpiece W and the workpiece power supply support portion 73 are in close contact with each other at the contact surfaces of the workpiece W and the workpiece power supply support portion 73.

[0120] Here, the expression “the outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply support portion 73 completely come into contact with each other” means that the contact surfaces of the outer peripheral side surface of the workpiece W and the outer peripheral side surface of the workpiece power supply support portion 73 are in contact with each other continuously without interruption in the y-axis direction, that is, in the axial direction of the workpiece W.

[0121] Fig. 11 is a conceptual diagram illustrating an example of a state of the thin plates just before the completion of cutting in the wire electric discharge machining apparatus 1000 according to the first embodiment. Fig. 12 is an enlarged view showing a specific area A in Fig. 11 illustrates. Fig. 11 illustrates a schematic diagram of a cross section at a position where an outer peripheral side surface Ws of the workpiece W and an outer peripheral side surface 73s of the workpiece power supply support portion 73 are in contact with each other just before the end of cutting into the thin plates. The cross section at the position where the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 are in contact with each other is a cross section taken in an xz plane passing through the center axis C of the workpiece W. An arrow 83 in Fig. 11 indicates the supply path for electrical discharge machining power from the machining fluid flow rectifying plate 71a.

[0122] It is believed that even if the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 are highly accurately polished and flattened, in a structure where the outer peripheral side surfaces of rigid bodies that do not deform abut each other, a microscopically tiny gap is generated in contact portions that are abutting portions. Therefore, it is considered difficult to make the rigid bodies that do not deform contact each other over the entire outer peripheral side surfaces thereof. An example of the dimension of the tiny gap is approximately 10 μm or more and 50 μm or less.In addition, depending on the accuracy of the straightness of the workpiece W and the workpiece power supply support portion 73 with respect to the facing surface 71 as the installation surface on the machining fluid flow rectifying plate 71a on which the workpiece W and the workpiece power supply support portion 73 are installed and fixed, a minute gap of about 100 μm or more and 300 μm or less, which is larger than the wire diameter of the wire electrode 1 used, may be generated.

[0123] Even when the workpiece power supply support portion 73 is partially in contact with the workpiece W, the workpiece power supply support portion 73 can supply the workpiece W with the electrical discharge machining power supplied from the machining power supply 5. However, a situation may be assumed where, immediately before the completion of cutting into the plurality of thin plates formed from the workpiece W, the electrical discharge machining power supply path from the machining power supply 5 via the machining fluid flow rectifying plate 71a and the workpiece power supply support portion 73 is interrupted with respect to the thin plate portion separated from the workpiece W.

[0124] An example of a case where the situation is assumed in which the supply path for electrical discharge machining power is interrupted as described above is a case where the machining by some portions of the wire electrode 1 among the cutting wire parts 1b slightly precedes the completion of cutting into the plurality of thin plates formed from the workpiece W, or a case where a remaining machining portion of the workpiece W that has not yet been cut becomes much smaller, resulting in the mechanical strength of the remaining machining portion decreasing and thus cracking occurring in the thin plates in the cutting process.

[0125] In the Fig. 11 and Fig. 12, the machining by some portions of the wire electrode 1 among the cutting wire parts 1b is preceded just before the completion of cutting into the plurality of thin plates formed from the workpiece W, and the supply path of electrical discharge machining power from the machining fluid flow rectifying plate 71a to the workpiece W is interrupted. On the other hand, since the outer peripheral side surface 73s of the workpiece power supply supporting portion 73 and the outer peripheral side surface Ws of the workpiece W are partially in contact with each other, the supply of electrical discharge machining power from the machining fluid flow rectifying plate 71a to the workpiece W via the workpiece power supply supporting portion 73 is continuously performed.

[0126] When the supply path for electrical discharge machining power is interrupted shortly before the completion of cutting into the plurality of thin plates, electrical discharge machining is suspended, resulting in a thin plate that is not separated due to the presence of a remaining machining portion, or a thin plate that cracks at the boundary of the remaining machining portion. Furthermore, the machining between the electrodes, which is a machining gap for electrical discharge machining in the machining direction, easily precedes a tip of each cutting wire portion 1b. Therefore, the thin plates are cut and separated before the cutting wire portions 1b completely pass through the workpiece W.As a result, remaining machining portions remain as tiny residual protrusions at the machining end portions of the separated thin plates, thereby reducing the cutting quality and yield of the thin plates.

[0127] Fig. 13 is a conceptual diagram illustrating an example of a state of thin plates just before the completion of cutting in the wire electric discharge machining apparatus 1000a according to the second embodiment. Fig. 14 is an enlarged view showing a specific area B in Fig. 13 illustrates. Fig. 13 illustrates a schematic diagram of a cross section at a position where the conductive connecting part 77 and each of the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 are in contact with each other just before the completion of cutting into the thin plates. The cross section at the position where the conductive connecting part 77 and each of the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 are in contact with each other is a cross section in the xz plane passing through the central axis C of the workpiece W. The arrow 83 in Fig. 13 indicates the supply path for electrical discharge machining power from the machining fluid flow rectifying plate 71a.

[0128] In Fig. 13, the conductive connecting part 77 provided between the workpiece W and the workpiece power supply supporting portion 73 is sandwiched between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply supporting portion 73, and is pressed against the outer peripheral side surface Ws of the workpiece W together with the workpiece power supply supporting portion 73.

[0129] The conductive connecting part 77 is deformed by pressing against the outer peripheral side surface Ws of the workpiece W and fills a gap between the outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W that face each other. Consequently, the contact area between the outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W that face each other is increased. Consequently, in the wire electrical discharge machining apparatus 1000a, the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 can be brought into full contact with each other, and the conductivity between the workpiece power supply support portion 73 and the workpiece W is improved.

[0130] In the Fig. 13 and Fig. 14, since the outer peripheral side surface 73s of the workpiece power supply supporting portion 73 and the outer peripheral side surface Ws of the workpiece W are electrically connected via the conductive connecting member 77, the supply of the electrical discharge machining power from the machining fluid flow rectifying plate 71a to the workpiece W via the workpiece power supply supporting portion 73 and the conductive connecting member 77 is continuously performed even after the completion of cutting into the plurality of thin plates formed from the workpiece W.

[0131] As described above, a material such as a low-melting-point metal or a porous metal that has flexibility and easy deformability is preferably used for the conductive connecting part 77. Due to the easy deformability property of the conductive connecting part 77, the conductive connecting part 77, which is pressed against the two outer peripheral side surfaces, that is, the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support section 73, is deformed.Then, the gap between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 is filled with the thus deformed conductive connecting part 77, and thereby the contact area between the outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W facing each other is increased.

[0132] Even in a case where contact portions of the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 are not parallel to each other, the conductive connecting part 77 is deformed to fit into the gap between the outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W that face each other, and fill the gap. Even if there are minute irregularities in the contact portions of the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73, the deformed conductive connecting part 77 fits into a gap caused by the minute irregularities between the outer peripheral side surfaces of the workpiece power supply support portion 73 and the workpiece W that face each other, and the gap is filled.

[0133] Consequently, in the wire electrical discharge machining apparatus 1000a, the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 can be brought into full contact with each other, and the conductivity between the workpiece power supply support portion 73 and the workpiece W is improved. The workpiece power supply support portion 73 and the conductive connecting part 77 can form the supply path for electrical discharge machining power from the machining fluid flow rectifying plate 71a to the workpiece W and the plurality of thin plates in the cutting process from the start of cutting to the completion of cutting. Consequently, the wire electrical discharge machining apparatus 1000a can stably continue the wire cutting of the workpiece W.

[0134] In the wire electrical discharge machining apparatus 1000a having the above configuration, even in a case where, in the cutting performed at a plurality of portions by the cutting wire parts 1b, the workpiece W is cut by some portions of the wire electrode 1 among the cutting wire parts 1b slightly faster than by other portions of the wire electrode 1 among the cutting wire parts 1b, it is possible to prevent the occurrence of the interruption of the power supply path from the machining power supply 5 to the plurality of thin plates in the cutting process, which occurred in a case where there is no supply path for electrical discharge machining power to the workpiece W and the plurality of thin plates in the cutting process other than that from the machining fluid flow rectifying plate 71a.

[0135] Therefore, in the wire discharge machining apparatus 1000a, the wire electrode 1 constituting the cutting wire portions 1b completely passes through the workpiece W while continuing cutting without interrupting the cutting, and reaches the conductive connecting portion 77. As a result, in the plurality of thin plates cut by the wire discharge machining apparatus 1000a, residual protrusions, which are remaining machining portions due to the interruption of cutting, do not occur at the machining end portions, and the cutting quality and yield are improved.

[0136] As described in the first embodiment, a conductive wax may be used to fix the workpiece W and the workpiece power supply support portion 73 to the machining fluid flow rectifying plate 71a. In a case where such a conductive wax is used to fix the workpiece W and the workpiece power supply support portion 73 to the machining fluid flow rectifying plate 71a, the melting point of a conductive wax for fixing the workpiece W to the machining fluid flow rectifying plate 71a is preferably higher than the melting point of a conductive wax for fixing the workpiece power supply support portion 73 to the machining fluid flow rectifying plate 71a.For example, the workpiece W is fixed to the machining fluid flow rectifying plate 71a by using a conductive wax having a melting point of about 60°C, and then the workpiece power supply supporting portion 73 is fixed to the machining fluid flow rectifying plate 71a by using a conductive wax having a melting point of about 40°C in a state where the outer peripheral surface of the workpiece power supply supporting portion 73 is in contact with the outer peripheral surface of the workpiece W.In a case where the conductive waxes satisfying the above conditions are used, the workpiece W is first fixed to the machining fluid flow rectifying plate 71a, and then the workpiece power supply supporting portion 73 can be fixed to the machining fluid flow rectifying plate 71a while the outer peripheral side surface 73s of the workpiece power supply supporting portion 73 is reliably brought into contact with the outer peripheral side surface Ws of the workpiece W.

[0137] It should be noted that the conductive connecting part 77 can be used between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surfaces of the side surface holding portions 75a and 75b for thin plates.

[0138] Furthermore, in the wire electrical discharge machining apparatus 1000a, the conductive connecting part 77 increases the contact area between the workpiece power supply support portion 73 and the workpiece W, the workpiece power supply support portion 73 increases a force for holding the workpiece W, and the flow rate of the machining fluid is reduced near the machining end portion where the machining degree, i.e., the cutting length, decreases rapidly. This makes it possible to perform electrical discharge cutting on the thin plates without damaging the thin plates near the machining end portions. Therefore, in the wire electrical discharge machining apparatus 1000a, the side surface holding portions 75a and 75b for thin plates can be omitted.

[0139] As described above, the wire electric discharge machining apparatus 1000a according to the second embodiment has a similar effect to the wire electric discharge machining apparatus 1000 according to the first embodiment described above.

[0140] Furthermore, the wire electrical discharge machining apparatus 1000a includes the conductive connection part 77 between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73. Consequently, in the wire electrical discharge machining apparatus 1000a, it is possible to increase the contact area between the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73, bring the outer peripheral side surface Ws of the workpiece W and the outer peripheral side surface 73s of the workpiece power supply support portion 73 into full contact with each other, and improve the conductivity between the workpiece power supply support portion 73 and the workpiece W.Therefore, in the wire electrical discharge machining apparatus 1000a, it is possible to prevent the occurrence of minute residual protrusions attributable to the interruption of the supply path for electrical discharge machining power shortly before the completion of cutting into the plurality of thin plates from the workpiece W, and to improve the cutting quality and the yield of the thin plates. Third embodiment.

[0141] Fig. 15 is a schematic view illustrating an exemplary configuration of the thin plate side surface holding portions 75a and 75b of a thin plate machining stabilizing unit 70b included in a wire electric discharge machining apparatus 1000b according to a third embodiment. Fig. 15 illustrates the machining fluid flow rectifying plate 71a, the workpiece support unit 72, the workpiece power supply supporting section 73, the thin plate side surface holding sections 75a and 75b, and the thin plate section support 76 in the thin plate machining stabilizing unit 70b included in the wire electric discharge machining apparatus 1000b. Fig. 16 is an enlarged view showing a specific area D in Fig. 15 illustrates. Fig. 17 is another enlarged view showing the specific area D in Fig. 15 illustrates. Fig. 16 illustrates a first exemplary shape of the thin plate side surface holding portions 75a and 75b included in the thin plate processing stabilizing unit 70b. Fig. 17 illustrates a second exemplary shape of the thin plate side surface holding portions 75a and 75b included in the thin plate processing stabilizing unit 70b.

[0142] The wire electric discharge machining apparatus 1000b according to the third embodiment includes the thin plate machining stabilizing unit 70b instead of the thin plate machining stabilizing unit 70, which is different from the wire electric discharge machining apparatus 1000 according to the first embodiment. In the thin plate machining stabilizing unit 70b, the shape of the thin plate side surface holding portions 75a and 75b differs from that of the thin plate side surface holding portions 75a and 75b according to the first embodiment. The other configuration of the wire electric discharge machining apparatus 1000b according to the third embodiment is similar to that of the wire electric discharge machining apparatus 1000 according to the first embodiment, and redundant description will not be repeated.

[0143] The thin plate side surface holding portions 75a and 75b installed in the machining path of the workpiece W have a function of preventing the plurality of thin plates formed from the workpiece W from shaking due to a force received from the machining fluid flow, and a function of supplying electrical discharge machining power to each thin plate. Therefore, regarding a contact state between the workpiece W and the thin plate side surface holding portions 75a and 75b, surface contact is more advantageous than line contact from the viewpoint of improving a force for holding the thin plates and stable power supply to the thin plates.That is, by adjusting the contact state between the workpiece W and the thin plate side surface holding portions 75a and 75b to face contact, the contact area between the workpiece W and each of the thin plate side surface holding portions 75a and 75b is increased, and the state of the thin plates held by the thin plate side surface holding portions 75a and 75b during cutting is further stabilized. By further stabilizing the state of the thin plates held by the thin plate side surface holding portions 75a and 75b during cutting, it is possible to perform cutting while increasing the electrical discharge machining speed, and the cutting quality is improved.

[0144] Therefore, a contact surface 75e on an outer peripheral side surface 75d of each of the thin plate side surface holding portions 75a and 75b to be in contact with the outer peripheral side surface Ws of the workpiece W preferably has a shape formed along the shape of the outer peripheral side surface Ws of the workpiece W. Regarding the contact surface 75e at which the outer peripheral side surface 75d of each of the thin plate side surface holding portions 75a and 75b is in contact with the outer peripheral side surface Ws of the workpiece W, when the length of the contact surface 75e in the circumferential direction of the outer peripheral side surface Ws of the workpiece W is about 3 mm, the reliability of the force for holding the thin plates and the stable power supply to each thin plate are improved.

[0145] The thin plate side surface holding section 75b has, in the Fig. 16 has a columnar shape in which a shape thereof in a planar direction perpendicular to the x-axis direction is a circular shape, and a shape of the contact surface 75e in contact with the outer peripheral side surface Ws of the workpiece W in the planar direction perpendicular to the x-axis direction is formed in an arc shape, which is a shape formed along the shape of the outer peripheral side surface Ws of the workpiece W. In the thin plate side surface holding portion 75b in the first exemplary form configured as described above, the contact state with the workpiece W is surface contact at the contact surface 75e.Therefore, the thin plate side surface holding portion 75b in the first exemplary embodiment is superior in terms of the force for holding the thin plates and the stable power supply to the thin plates compared to the thin plate side surface holding portion 75b in which the contact state with the workpiece W is line contact. Although the thin plate side surface holding portion 75b has been described here, the same applies to the thin plate side surface holding portion 75a and the workpiece power supply support portion 73.

[0146] The thin plate side surface holding section 75b has, in the Fig. 17, the second exemplary shape illustrated has a rectangular columnar shape or a prismatic columnar shape, a shape of which in a planar direction perpendicular to the x-axis direction is a square shape, and a shape of the contact surface 75e in contact with the outer peripheral side surface Ws of the workpiece W in the planar direction perpendicular to the x-axis direction is formed in an arc shape, which is a shape formed along the shape of the outer peripheral side surface Ws of the workpiece W. In the thin plate side surface holding portion 75b in the second exemplary shape configured as described above, the contact state with the workpiece W is surface contact at the contact surface 75e.Therefore, the thin plate side surface holding portion 75b in the second exemplary form is superior in terms of the force for holding the thin plates and the stable power supply to the thin plates compared to the thin plate side surface holding portion 75b in which the contact state with the workpiece W is line contact. Although the thin plate side surface holding portion 75b has been described here, the same applies to the thin plate side surface holding portion 75a.

[0147] The material used for the thin plate side surface holding portions 75a and 75b is preferably a material having electrical discharge machining properties similar to those of the workpiece W. In a case where the workpiece W made of SiC is cut, the thin plate side surface holding portions 75a and 75b are preferably formed of, for example, silicon carbide or a sintered member made of silicon carbide powder. By machining a mass obtained by sintering the SiC powder to produce the thin plate side surface holding portions 75a and 75b, the material costs of the thin plate side surface holding portions 75a and 75b can be reduced.

[0148] A case where standard metal such as copper, brass, iron, or aluminum is used for the thin plate side surface holding portions 75a and 75b when cutting the thin plates from the workpiece W made of a material such as silicon carbide or gallium nitride, and a case where cemented silicon carbide is used for the thin plate side surface holding portions 75a and 75b when cutting are performed were considered.As a result, it was confirmed in machining experiments by the inventors of the present invention that in the case where cemented silicon carbide is used for the side surface holding portions 75a and 75b for thin plates, damage to the wire electrode 1 by the electrical discharge machining is extremely small in view of the degree of wear of the wire electrode 1 due to the electrical discharge machining and a change in the electrical discharge machining properties caused by the re-deposition of residues generated by the electrical discharge machining on the surface of the wire electrode 1.

[0149] However, among these materials, silicon carbide and gallium nitride have relatively high hardness, are easily chipped upon impact, and are difficult to machine by cutting. Therefore, for thin plates made of silicon carbide, the side surface holding portions 75a and 75b are formed by cutting from a mass member using wire electrical discharge machining. This machining method can easily perform high-precision shape machining based on machining locations by an NC program, is non-contact thermal machining, and is not affected by the hardness or brittleness of a material.The side surface holding portions 75a and 75b for thin plates made of silicon carbide or gallium nitride are used for cutting the workpiece W made of a semiconductor material such as silicon carbide, gallium nitride, silicon (Si) or gallium oxide (Ga2O3) into a plurality of thin plates by electrical discharge machining by the cutting wire parts 1b.

[0150] As described above, in the wire electrical discharge machining apparatus 1000b according to the third embodiment, the contact surface 75e on the outer peripheral side surface 75d of each of the thin plate side surface holding portions 75a and 75b, which is to be in contact with the outer peripheral side surface Ws of the workpiece W, has a shape formed along the shape of the outer peripheral side surface Ws of the workpiece W. That is, the contact surface 75e has a shape formed along the shape of the outer peripheral side surface Ws of the workpiece W, which is a concave shape corresponding to a convex shape of the outer peripheral side surface Ws of the workpiece W.Consequently, in the wire electrical discharge machining apparatus 1000b, the contact area between the workpiece W and each of the side surface thin plate holding portions 75a and 75b is increased, the state of the thin plates during cutting held by the side surface thin plate holding portions 75a and 75b is further stabilized, and the electrical discharge machining speed and cutting quality are improved.

[0151] Next, a hardware configuration of the control unit 300 according to the first to third embodiments will be described. Functions of the control unit 300 included in each of the wire-cutting electrical discharge machining devices 1000, 1000a, and 1000b are implemented by a processing circuit. The processing circuit is dedicated hardware mounted on the control unit 300 of each of the wire-cutting electrical discharge machining devices 1000, 1000a, and 1000b. The processing circuit may be a processor that executes a program stored in a memory.

[0152] Fig. 18 is a diagram illustrating a hardware configuration in a case where functions of the control unit 300 included in each of the wire-cutting electrical discharge machining devices 1000, 1000a, and 1000b are implemented by dedicated hardware. A processing circuit 51 as the dedicated hardware is a single circuit, a compound circuit, a programmed processor, a parallel programmed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof.

[0153] Fig. 19 is a diagram illustrating a hardware configuration in a case where the Fig.The functions of the control unit 300 illustrated in FIG. 18, which are included in each of the wire-cutting machining devices 1000, 1000a, and 1000b, are implemented by a processor executing a program stored in a memory. A processor 53 and a memory 54 are communicatively connected to each other. The processor 53 is a central processing unit (CPU), a processing device, a computing device, a microprocessor, a microcomputer, or a digital signal processor (DSP). The functions of the control unit 300 are implemented by the processor 53 and software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 54.The memory 54 is a built-in memory, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM (registered trademark)).

[0154] Some of the functions of the control unit 300 can be implemented by dedicated hardware, and other parts of the functions of the control unit 300 can be implemented by software or firmware. Thus, the functions of the control unit 300 can be implemented by hardware, software, firmware, or a combination thereof.

[0155] The configurations described in the above embodiments are merely examples and may be combined with other known techniques, the embodiments may be combined with each other, and part of the configurations may be omitted or modified without departing from the gist thereof. List of reference symbols

[0156] 1 wire electrode; 1a parallel wire part; 1b cutting wire part; 2, 2a, 2b, 2c, 2d guide roller; 2e guide groove; 3, 3a, 3b spool; 4a, 4b damping guide roller; 5 machining power supply; 6a, 6b power supply contact unit; 7a, 7b nozzle; 7c machining fluid ejection hole; 8a, 8b spool rotation control device; 9a, 9b traverse control device; 10 cutting feed table; 31 machining control device; 32 waveform control device; 33 machining state detection unit; 34 cutting table drive control device; 35 wire travel control device; 36 workpiece support unit holding control device; 51 processing circuit; 53 processor; 54 memory; 70, 70a, 70b thin plate machining stabilization unit; 71, 71a, 71b machining fluid flow rectifying plate; 71as, 71bs facing surface; 72 workpiece receiving unit; 72a groove portion; 73 workpiece power supply supporting portion; 73s, 75d, Ws outer peripheral side surface; 74 machining fluid supply pipe;75a, 75b thin plate side surface holding portion; 75c thin plate portion; 75e contact surface; 75g, 77g machined groove; 76 thin plate portion holder; 77 conductive connecting part; 78 workpiece receiving unit holding device; 100 machining mechanism unit; 200 power supply unit; 300 control unit; 1000, 1000a, 1000b wire EDM machining device; A, B, D concrete area; C central axis; PD diameter portion position; PE machining end position; PH machining start position; W workpiece; Wg machined groove; QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2020 / 213040 A1

[0005] JP 2015-120235

[0005]

Claims

[1] A wire electrical discharge machining apparatus that generates electric discharge between a plurality of cutting wire members that rotate and a workpiece to perform electrical discharge machining on the workpiece with energy generated by the electric discharge and simultaneously cut off a plurality of wafers from the workpiece, the wire electrical discharge machining apparatus comprising: a wire electrode including the plurality of cutting wire parts spaced parallel to each other and facing the workpiece; a power supply unit for generating electrical discharge between the plurality of cutting wire members and the workpiece; a pair of machining fluid flow rectifying plates having conductivity and connected to a power supply and provided in contact with both sides of the workpiece to enclose the workpiece; a pair of nozzles into which the plurality of cutting wire members are inserted, the pair of nozzles including a plurality of machining fluid ejection holes that eject a machining fluid toward a space enclosed between the pair of machining fluid flow rectifying plates to supply the machining fluid to a gap between the plurality of cutting wire members and the workpiece; a cutting feed table for moving the pair of machining fluid flow rectifying plates up and down relative to the plurality of cutting wire members; a workpiece holding unit for holding the workpiece to be cut during cutting from above the workpiece and the plurality of cutting wire parts; and a lower workpiece holding portion having conductivity to contact the workpiece from below to hold the workpiece. [2] The wire electric discharge machining apparatus according to claim 1, wherein the pair of machining fluid flow rectifying plates comprises: a first machining fluid flow rectifying plate provided so as to contact an end face of the workpiece in a direction parallel to the wire, that is, a direction in which the cutting wire parts are arranged in parallel, and connected to the power supply; and a second machining fluid flow rectifying plate provided so as to be in contact with another end face of the workpiece in the wire parallel direction, and the lower workpiece holding portion is fixed to a facing surface of the first machining fluid flow rectifying plate, wherein the facing surface is a surface of the first machining fluid flow rectifying plate facing the second machining fluid flow rectifying plate. [3] The wire-cutting machine according to claim 2, wherein the lower workpiece holding portion comprises: a workpiece power supply support portion fixed to the first machining fluid flow rectifying plate in a state of being in contact with an outer peripheral side surface of a machining end portion, that is, a portion where cutting of the workpiece by the cutting wire members is completed; and a thin plate side surface holding portion provided above upper and lower portions of the machining end portion in an up-and-down direction below and fixed to the first machining fluid flow rectifying plate in a state of being in contact with an outer peripheral side surface of the workpiece. [4] The wire electric discharge machining apparatus according to claim 3, wherein the workpiece power supply support portion is arranged just below the machining end portion. [5] Wire erosion machining apparatus according to claim 3 or 4, comprising: a conductive connecting member having flexibility and arranged to be sandwiched between the workpiece power supply supporting portion or the thin plate side surface holding portion and the workpiece, and filling a gap between the workpiece power supply supporting portion or the thin plate side surface holding portion and the workpiece. [6] The wire electrical discharge machining apparatus according to claim 5, wherein the conductive connecting part is formed with a flexible conductive material having an elastic modulus of 80 Gpa or less and an electrical resistance value of 10 Ω cm or less. [7] The wire electric discharge machining apparatus according to any one of claims 3 to 6, wherein, in a cutting direction of the workpiece, a contact position of an outer peripheral side surface of the thin plate side surface holding portion with respect to the outer peripheral side surface of the workpiece is located in a portion where an uncut length, that is, a length of the workpiece that is not yet cut, is 1 / 2 or less of a total cutting length of the workpiece, the portion being located at a position higher than a position where an outer peripheral side surface of the workpiece power supply assisting portion is in contact with the outer peripheral side surface of the workpiece. [8] The wire electrical discharge machining apparatus according to claim 7, wherein the side surface thin plate holding portion is cut together with the workpiece, and a plurality of thin plate portions of the side surface thin plate holding portion formed by cutting the side surface thin plate holding portion support and fix a plurality of wafers formed by cutting from the workpiece simultaneously with the thin plate portions and separating them from each other. [9] The wire electric discharge machining apparatus according to any one of claims 3 to 8, wherein the thin plate side surface holding portion includes silicon carbide or a sintered member made of silicon carbide powder. [10] Wire erosion machining apparatus according to one of claims 3 to 9, comprising: a position changing mechanism that changes positions of the first machining fluid flow rectifying plate and the second machining fluid flow rectifying plate so that they are relatively rotated with respect to the cutting wire parts or relatively inclined with respect to the cutting wire parts, and fixes the first machining fluid flow rectifying plate and the second machining fluid flow rectifying plate. [11] A wire electrical discharge machining method for generating an electric discharge between a plurality of cutting wire members rotating and a workpiece to perform electrical discharge machining on the workpiece with energy generated by the electric discharge and simultaneously cutting off a plurality of wafers from the workpiece, the wire electrical discharge machining method comprising: a machining fluid flow rectifying step of ejecting a machining fluid from a nozzle toward a space enclosed between a pair of machining fluid flow rectifying plates connected to a power supply, guiding a flow of the machining fluid toward the workpiece through facing surfaces of the pair of machining fluid flow rectifying plates, and supplying the machining fluid to a gap between the plurality of cutting wire members and the workpiece; a wafer holding step for holding the workpiece to be divided during cutting from above the workpiece and the plurality of cutting wire parts; and a wafer supporting step of, in a state where a lower workpiece holding portion having conductivity comes into contact with the workpiece from below to hold the workpiece during cutting of the workpiece, the lower workpiece holding portion being provided over upper and lower regions of a machining end portion, which is a portion where cutting of the workpiece is completed in a cutting direction of the workpiece, and being fixed to the facing surface of one of the pair of machining fluid flow rectifying plates, supplying power from the pair of machining fluid flow rectifying plates to the workpiece via the lower workpiece holding portion from the start of cutting of the workpiece to the end of cutting of the workpiece. [12] The wire discharge machining method according to claim 11, wherein the pair of machining fluid flow rectifying plates comprises: a first machining fluid flow rectifying plate provided so as to contact an end face of the workpiece in a direction parallel to the wire, that is, a direction in which the cutting wire parts are arranged in parallel, and connected to the power supply; and a second machining fluid flow rectifying plate provided so as to be in contact with another end face of the workpiece in the wire parallel direction, and the lower workpiece holding portion comprises: a workpiece power supply support portion fixed to the first machining fluid flow rectifying plate in a state of being in contact with an outer peripheral side surface of a machining end portion, that is, a portion where cutting of the workpiece by the cutting wire members is completed; and a thin plate side surface holding portion provided above upper and lower portions of the machining end portion in an up-and-down direction below and fixed to the first machining fluid flow rectifying plate in a state of being in contact with an outer peripheral side surface of the workpiece. [13] A wafer manufacturing process comprising: simultaneously cutting out a plurality of wafers from the workpiece by the wire discharge machining method according to claim 11 or 12. [14] The wafer manufacturing method according to claim 13, wherein the workpiece is a semiconductor ingot and the wafer is a semiconductor wafer.

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