METHOD FOR MACHINING A WORKPIECE

Abstract

Method for machining a plate-shaped workpiece (11) comprising layered bodies (25) containing metal, which are formed in a superimposed relationship with projected division lines (19), comprising the following steps: Holding the workpiece (11) on a holding table; and then cutting the workpiece along the projected division lines (19) with a ring-shaped cutting blade (8), thereby dividing the layered bodies (25); wherein the cutting blade (8) has a groove (8d) formed in a surface side (8a) or a rear side (8b) of an outer circumferential section thereof, which cuts into the workpiece (11) in the step of cutting the workpiece (11); and The step of cutting the workpiece (11) includes the step of cutting the workpiece (11) while a cutting fluid (12) containing an organic acid and an oxidizing agent is supplied to the workpiece (11), wherein the holding table has a holding surface (4a) in which outlet grooves (4b) are arranged, dividing the holding surface (4a) into several areas according to the division lines (19), wherein the outlet grooves (4b) each have a width greater than the width of the cutting blade (8) and a depth greater than the distance by which the cutting blade (8) projects through the workpiece (11) towards the holding table when cutting through the workpiece (11).

Description

Field of invention

[0001] The present invention relates to a method for machining a plate-shaped workpiece comprising layered bodies containing metal, which are formed in an overlapping relationship to projected division lines. Description of the state of the art

[0002] Electronic devices, typically mobile phones and personal computers, use component chips as essential components. These chips have electronic components such as circuits formed on them. A component chip is manufactured by dividing the face of a wafer, made of a semiconductor material such as silicon, into several areas with multiple projected division lines, also known as roads. Components are formed in the respective areas, and then the wafer is divided into component chips according to the component placement along the projected division lines.

[0003] In recent years, evaluation elements, often referred to as TEGs (Test Element Groups), have frequently been used to evaluate the electrical properties of devices along projected division lines on wafers as described above (see, for example, Japanese patent applications JP H06-349926A and JP 2005-21940A). The TEGs at the projected division lines on a wafer make it possible to maximize the number of device chips that can be fabricated from a single wafer. Once the TEGs have completed their evaluations and are no longer needed, they can be removed when the wafer is divided into device chips.

[0004] US 2015 / 0 262 881 A1 discloses the use of a cutting blade for cutting a workpiece, wherein a cutting fluid containing an organic acid and an oxidizing agent is supplied during the cutting of the workpiece.

[0005] JP S61 - 214 977 A, US 2005 / 0 178 241 A1 and JP 2013 - 84 811 A each disclose a cutting blade with a groove for cutting a workpiece.

[0006] JP 2008 - 126 369 A discloses a cutting blade for cutting a workpiece, which has a slot open at an outer circumferential edge thereof.

[0007] The component chips referred to above are typically encapsulated in plastic before being mounted on boards or similar components. For example, a packaged board is manufactured by encapsulating several component chips with plastic and then dividing them along projected division lines according to the component chips, resulting in packaged components, each with its own plastic-sealed component chip.

[0008] Several layered bodies containing metal are positioned along the projected division lines of the packaged plate. When the packaged plate is divided, the layered bodies are separated. The layered bodies are connected to the electrodes of the component chips via metal leads or similar connections. When the layered bodies are separated along with the packaged plate, they become the electrodes of the packaged components. PRESENTATION OF THE INVENTION

[0009] When layered bodies containing metal, used as TEGs, electrodes, etc., are cut and removed by a cutting blade formed from a binder with abrasive grains dispersed within it, the metal contained in the layered bodies is elongated, creating protrusions called "burrs" due to contact with the cutting blade. If the cutting blade processes the wafer at an increased speed, more heat is generated, resulting in larger burrs. Therefore, depending on the processing method using the cutting blade, it is necessary to reduce the processing speed to prevent a decrease in wafer processing quality.

[0010] Therefore, an objective of the present invention is to provide a method for machining a plate-shaped workpiece comprising layered bodies containing metal, which are formed in a superimposed relationship with projected division lines, at an increased speed while maintaining the quality of the machining of the workpieces.

[0011] In accordance with one aspect of the present invention, a method for machining a plate-shaped workpiece is provided, comprising layered bodies containing metal, which are arranged in a superimposed relationship with projected parting lines, comprising the steps of holding the workpiece on a holding table and then cutting the workpiece along the projected parting lines with an annular cutting blade, thereby separating the layered bodies, wherein the cutting blade has a groove in a face side or a rear side of an outer circumferential section, which cuts into the workpiece in the step of cutting the workpiece, and the step of cutting the workpiece includes the step of cutting the workpiece while a cutting fluid containing an organic acid and an oxidizing agent is supplied to the workpiece.

[0012] In this aspect of the present invention, the groove can extend radially along a radial direction of the cutting blade. Alternatively, the groove can extend annularly along a circumferential direction of the cutting blade.

[0013] According to the method in accordance with the present invention, the cutting fluid, which contains an organic acid and an oxidizing agent, is supplied to the cutting blade and the workpiece when the layered bodies containing metal are cut with the cutting blade. The organic acid and the oxidizing agent effectively modify the metal contained in the layered bodies, thereby reducing the ductility of the metal as the cutting blade cuts the layered bodies. Consequently, the metal is prevented from forming burrs, even when the workpiece is machined at increased speed.

[0014] According to the method in accordance with the present invention, the cutting blade, which has a groove in the surface or rear side of the outer circumferential section, is used. The groove allows the cutting fluid to be efficiently guided to the layered bodies, enabling the cutting fluid to sufficiently modify the metal contained within the layered bodies to reduce its ductility as the cutting blade separates the layered bodies. This prevents the metal from forming burrs, even when the workpiece is machined at increased speed. In other words, the machining speed can be increased while maintaining the quality of the workpiece machining.

[0015] According to the inventive method, the holding table has a holding surface in which outlet grooves are arranged that divide the holding surface into several areas according to the division lines, wherein the outlet grooves each have a width that is greater than the width of the cutting blade and a greater depth than the distance by which the cutting blade projects through the workpiece in the direction of the holding table when cutting through the workpiece.

[0016] The above and other aims, features and advantages of the present invention and the manner of realizing them will be made clearer and the invention itself best understood by studying the following description, the claims attached to it, with reference to the attached figures, which show a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE FIGURES Fig. 1A is a top view that schematically shows an example of a workpiece; Fig. 1B is a top view of the workpiece from below; Fig. 2A is an enlarged partial view in cross-section, representing a holding step of a machining process for a workpiece according to an embodiment of the present invention; Fig. 2B is a side view, partly in cross-section, showing a cutting step of the workpiece of the machining process for a workpiece according to the embodiment; Fig. 3A is a front view schematically showing a cutting blade; Fig. 3B is a front view schematically showing a cutting blade according to one modification; and Fig. Figure 4 is a front view of a nozzle for supplying a cutting fluid according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED VERSION

[0017] A method for machining a workpiece according to an embodiment of the present invention is described below with reference to the accompanying figures. The method for machining a workpiece according to the present embodiment, which is also referred to as the "workpiece machining method," is a method for machining a plate-shaped workpiece comprising layered bodies containing metal, arranged in a superimposed relationship with projected parting lines, and includes a holding step (see Figure 1). Fig. 2A) and a cutting step (see Fig. 2B and Fig. 3).

[0018] In the holding step, a workpiece is held on a clamping table (holding table) of a cutting device. In the cutting step, while the workpiece is supplied with a cutting fluid containing an organic acid and an oxidizing agent, the workpiece is cut along projected parting lines by an annular cutting blade having multiple slots open on an outer circumferential section, thereby dividing (separating) the workpiece along with the layered bodies. The machining process for a workpiece according to the present embodiment is described in detail below.

[0019] Fig. 1A is a top view that schematically shows a workpiece 11 as an example that is to be machined by the machining procedure for a workpiece according to the present embodiment. Fig. 1B is a top view of workpiece 11 from below. As in Fig. 1A and Fig. As shown in Figure 1B, workpiece 11 includes, for example, a packaged plate containing several component chips, not shown, encapsulated in plastic, and includes a metal frame 13 which has a rectangular shape in a top view.

[0020] The frame 13 is formed from an alloy 42, i.e., an alloy of iron and nickel or a metal such as copper or the like. The frame 13 has a surface 13a which is divided into several (three in this embodiment) component areas 15 and several circumferential edge areas 17, which surround the respective component areas 15. Each of the component areas 15 is further divided into several areas by a grid of projected division lines or roads 19, the areas containing respective steps 21.

[0021] A component chip, not shown, containing components such as ICs (integrated circuits), LEDs (light-emitting diodes), MEMs (microelectromechanical systems), etc., is formed on the rear side of each stage 21, i.e., on a rear side 13b of the frame 13. Encapsulating plastic layers 23 are formed in respective areas on the rear side 13b of the frame 13, corresponding to the component areas 15, which are arranged in a covering relationship to the component chips on the rear sides of the stages 21.

[0022] Several layered bodies 25 containing metal are arranged in a superimposed relationship with the projected division lines 19 around each of the steps 21. The layered bodies 25 are exposed on the surface 13a of the frame 13 and are connected to electrodes of the component chips by metal wires (not shown) or the like. The electrodes of the component chips, which are individually arranged on two adjacent steps 21, one on each side of the layered bodies 25, are connected to each of the layered bodies 25.

[0023] When the workpiece 11 is cut along the projected division lines 19 into packaged component chips with encapsulated component chips, the layered bodies 25 are also separated. The divided layered bodies 25 serve as the electrodes of the packaged components. Markings 27, which indicate the positions of the projected division lines 19, are formed in the outer circumferential edge regions 17 of the surface side of a 3a of the frame 13.

[0024] According to the present embodiment, the packaged plate in which the component chips are encapsulated by the encapsulating plastic layers 23 serves as the workpiece 11. However, the workpiece 11 is not limited to specific materials, shapes, structures, sizes, etc. Similarly, the component chips, the components, and the layered bodies 25 are not limited to specific types, quantities, shapes, structures, sizes, arrangements, etc.

[0025] For example, a wafer in which layered bodies serving as TEG (test element group) are formed in a superimposed relationship with projected division lines 19, or a wafer in which layered bodies containing metals such as titanium (Ti), nickel (Ni), gold (Au), etc., and serving as electrodes formed on the back side thereof, can be used as the workpiece 11.

[0026] In the machining process for a workpiece according to the present embodiment, the holding step is performed to hold the above workpiece 11 on a clamping table (holding table) of a cutting device. Fig. 2A is an enlarged partial sectional view showing the holding step. The holding step is performed using a cutting device 2, which is located in Fig. 2A, for example, is shown. Fig. 2A only the layered bodies 25 are shown as a component of the workpiece 11 for the purpose of illustration.

[0027] As in Fig. As shown in Figure 2A, the cutting device 2 has a clamping table (holding table) 4 for holding the workpiece 11 under suction. The clamping table 4 is arranged above a clamping base (not shown) connected to a suction source (not shown). The clamping base is coupled to a rotary actuator (not shown), such as a motor or the like, for rotation about an axis of rotation substantially parallel to a vertical direction. The clamping base is arranged above the machining feed mechanism (not shown), which moves the clamping base in a machining feed direction.

[0028] The clamping table 4 for holding the workpiece 11 is detachably mounted on an upper surface of the clamping base. The clamping table 4 comprises a flat plate, which, for example, has a rectangular shape in a top view, and has an upper surface portion that serves as a holding surface 4a for holding the workpiece 11 under suction. The clamping table 4 has several outlet grooves 4b formed in the holding surface 4a for alignment with the respective projected division lines 19. The outlet grooves 4b have upper ends that are open at the holding surface 4a. According to the invention, the outlet grooves 4b divide the holding surface 4a into several areas corresponding to the respective pieces or component chips into which the workpiece 11 is divided.

[0029] The clamping table 4 also includes suction holes 4c, which are formed vertically through it in the respective areas separated by the outlet grooves 4b, the suction holes 4c being open at the holding surface 4a and at a lower surface of the clamping table 4 opposite the holding surface 4a. When the clamping table 4 is installed on the upper surface of the clamping base, the suction holes 4c are connected to the suction source by suction channels formed in the clamping base.

[0030] In the holding step, the workpiece 11 is positioned on the holding surface 4a of the clamping table 4, such that the workpiece 11 has a rear side 11b, i.e., the side of the encapsulating plastic layer 23 or the rear side 13b of the frame 13, facing downwards, with the projected parting lines 19 aligned with the respective outlet grooves 4b. Subsequently, negative pressure from the suction source is applied to the rear side 11b of the workpiece 11 through the suction holes 4c. The workpiece 11 is now held under suction on the clamping table 4, such that the workpiece 11 has a surface 11a, i.e., the surface 13a of the frame 13, facing upwards.

[0031] The holding step is followed by a cutting step to cut the workpiece 11 along the projected division lines 19, thereby dividing (separating) the workpiece 11 together with the layered bodies 25. Fig. Figure 2B is a side view, partially in cross-section, depicting the cutting step. The cutting step is also performed using cutting device 2. As shown in Fig. As shown in Figure 2B, the cutting device 2 includes a cutting unit 6 which is arranged above the clamping table 4.

[0032] The cutting unit 6 has a spindle (not shown) that acts as a shaft essentially perpendicular to the machining feed direction. An annular cutting blade 8, formed from a bonding agent with abrasive grains dispersed therein, is mounted at one end of the spindle. The other outer end of the spindle is coupled to a rotary actuator (not shown), such as a motor or the like. The cutting blade 8 at one end of the spindle is rotatable about its own axis by forces transmitted by the rotary actuator.

[0033] The spindle is supported by a movement mechanism (not shown) which moves the cutting blade 8 in the index feed direction perpendicular to the machining feed direction and in a vertical direction perpendicular to both the machining feed direction and the index feed direction. A pair of nozzles 10 is arranged on the sides of a surface 8a and a rear side 8b of the cutting blade 8, which is thus positioned between the nozzles 10. The nozzles 10 are arranged so that a cutting fluid 12 can be supplied to the cutting blade 8 and workpiece 11.

[0034] According to the invention, each of the outlet grooves 4b has a width greater than the width of the cutting blade 8, i.e., for example, the distance between the surface 8a and the rear side 8b thereof, and a greater depth than the distance by which the cutting blade 8 projects downwards from the rear side 11b of the workpiece 11 when cutting through the workpiece 11. Therefore, when the cutting blade 8 cuts deeply into the workpiece 11 along the projected parting lines 19, the cutting blade 8 is not brought into contact with the clamping table 4.

[0035] According to the present embodiment, the cutting blade 8, which has several grooves formed in the surface side 8a and rear side 8b of an outer circumferential section that cuts into the workpiece 11, is used. In particular, Fig. 3A is a front view schematically showing the cutting blade 8. As in Fig. As shown in Figure 3A, the cutting blade 8 has several grooves 8d formed in the surface side 8a and the rear side 8b of an outer circumferential section (one side of an outer circumferential edge 8c). The grooves 8d extend radially along the radial directions of the cutting blade 8. The cutting fluid 12 from the nozzles 10 is effectively supplied to the layered bodies 25 through the grooves 8d.

[0036] In the cutting step, the clamping table 4 is rotated about its own axis to align a projected target dividing line 19 with the machining feed direction of the cutting device 2. The clamping table 4 and the cutting unit 6 are moved relative to each other to position the plane of the cutting blade 8 in alignment with the extension of the projected target dividing line 19. The lower end of the cutting blade 8 is then moved to a position below the rear side 11b of the workpiece 11.

[0037] Then, while the cutting blade 8 is rotated about its own axis, the clamping table 4 is moved in the machining feed direction. Simultaneously, the nozzles 10 deliver the cutting fluid 12, which contains an organic acid and an oxidizing agent, to the cutting blade 8 and the workpiece 11. The cutting blade 8 cuts into the workpiece 11 along the projected target parting line 19, thereby completely dividing the workpiece 11 together with the layered bodies 25 at the projected target parting line 19, thus forming a joint (slot) 11c in the width of the layered bodies 25 in the workpiece 11 along the projected parting lines 19.

[0038] The organic acid contained in the cutting fluid 12 modifies the metal in the layered bodies 25 to reduce its ductility. The oxidizing agent contained in the cutting fluid 12 facilitates surface oxidation of the metal in the layered bodies 25. As a result, the ductility of the metal in the layered bodies 25 is sufficiently reduced to improve the machinability of the workpiece 11.

[0039] The organic acid contained in the cutting fluid 12 can, for example, be a compound having at least one carboxyl group and at least one amino group in its molecule. In this case, it is preferred that at least one of the amino groups is a secondary or tertiary amino group. Additionally, the compound used in the organic acid can have a substituent group.

[0040] Amino acids can be used as the organic acid. Examples of amino acids that can be used here include glycine, dihydroxyethylglycine, glycylglycine, hydroxyethylglycine, N-methylglycine, β-alanine, L-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-alloisoleucine, L-isoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-thyroxine, L-tyrosine, 3,5-diiodo-L-tyrosine, β-(3,4-dihydroxyphenyl)-L-alanine, 4-hydroxy-L-proline, L-cysteine, L-methionine, L-ethionine. L-Lanthionine, L-Cystathionine, L-Cystine, L-Cystic acid, L-Glutamic acid, L-Aspartic acid, S-(Carboxymethyl)-L-Cysteine, 4-Aminobutyric acid, L-Asparagine, L-Glutamine, Azaserine, L-Canavanine, L-Citrulline, L-Arginine, δ-Hydroxy-L-Lysine, Creatine, L-Kynurenine, L-Histidine, 1-Methyl-L-Histidine, 3-Methyl-L-Histidine, L-Tryptophan, Actinomycin C1, Ergothioneine, Apamin, Angiotensin I, Angiotensin II, Antipain, etc.Among others, glycine, L-alanine, L-proline, L-histidine, L-lysine, and dihydroxyethylglycine are particularly preferred.

[0041] Aminopolyacids can also be used as the organic acid. Examples of aminopolyacids that can be used here include iminodiacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, nitrilotrismethylenephosphonic acid, ethylenediamine-N,N,N',N'-tetramethylenesulfonic acid, 1,2-diaminopropanetetraacetic acid, glycoletherdiaminetetraacetic acid, transcyclohexanediaminetetraacetic acid, ethylenediamineorthohydroxyphenylacetic acid, ethylenediaminedisuccinic acid (SS isomer), β-alaninediaacetic acid, N-(2-carboxyatoethyl)-L-aspartic acid, N-N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, etc.

[0042] Furthermore, carboxylic acids can be used as organic acids. Examples of carboxylic acids that can be used here include saturated carboxylic acids such as formic acid, glycolic acid, propionic acid, acetic acid, butyric acid, valeric acid, caproic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, malic acid, succinic acid, pimelic acid, mercaptoacetic acid, glyoxylic acid, chloroacetic acid, pyruvic acid, acetoacetic acid, etc.; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mesaconic acid, citraconic acid, aconitic acid, etc.; and cyclic unsaturated carboxylic acids such as benzoic acid, toluic acid, phthalic acid, naphthoic acids, pyromellitic acid, naphthalic acid, etc.

[0043] Oxidizing agents that may be contained in the cutting fluid 12 include, for example, hydrogen peroxide, peroxides, nitrates, iodates, periodates, hypochlorites, chlorites, chlorates, perchlorates, persulfates, dichromates, permanganates, cerates, vanadates, ozonated water, silver(II) salts, iron(III) salts, and their organic complex salts.

[0044] Furthermore, a corrosion inhibitor can be mixed into the cutting fluid 12. Mixing in the corrosion inhibitor prevents corrosion (elution) of the metal contained in the workpiece 11. A heterocyclic ring compound having at least three nitrogen atoms in its molecule and a fused ring structure, or a heterocyclic aromatic ring compound having at least four nitrogen atoms in its molecule, is preferably used as the corrosion inhibitor. The aromatic ring compound preferably comprises a carboxyl group, sulfo group, hydroxy group, or alkoxy group. Specifically preferred examples of the aromatic ring compound include tetrazole derivatives, 1,2,3-triazole derivatives, and 1,2,4-triazole derivatives.

[0045] Examples of tetrazole derivatives that can be used as corrosion protection include those that have no substituent group on the nitrogen atoms forming the tetrazole ring and that have a substituent group inserted at the 5-position of the tetrazole selected from the group consisting of a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group, or an alkyl group substituted with at least one substituent group selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group.

[0046] Examples of 1,2,3-triazole derivatives that can be used as corrosion inhibitors include those that have no substituent group on the nitrogen atoms forming the 1,2,3-triazole ring and that have a substituent group inserted at the 4-position and / or the 5-position of the 1,2,3-triazole, selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group, or an alkyl or aryl group substituted with at least one substituent group selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group.

[0047] Furthermore, examples of 1,2,4-triazole derivatives that can be used as corrosion protection include those that do not have a substituent group on the nitrogen atoms forming the 1,2,4-triazole ring and that, inserted at the 2-position and / or the 5-position of the 1,2,4-triazole, have a substituent group selected from the group consisting of a sulfo group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group, or an alkyl or aryl group substituted with at least one substituent group selected from the group consisting of a hydroxy group, a carboxyl group, a sulfo group, an amino group, a carbamoyl group, a carbonamide group, a sulfamoyl group and a sulfonamide group.

[0048] The above process is repeated to form joints 11c along all the projected parting lines 19, after which the cutting step is completed. According to the present embodiment, as described above, the cutting fluid 12, which contains an organic acid and an oxidizing agent, is supplied to the cutting blade 8 in the workpiece 11 as the layered bodies 25 containing metal are being cut by the cutting blade 8. The organic acid and the oxidizing agent effectively modify the metal contained in the layered bodies 25, thereby reducing the ductility of the metal as the cutting blade 8 cuts the layered bodies 25. This prevents the metal from forming burrs, even when the workpiece 11 is machined at an increased speed.

[0049] In the machining process for a workpiece according to the above embodiment, the cutting blade 8, which has grooves 8d formed in the surface 8a and the rear 8b of its outer circumferential section, is used. The grooves 8d effectively allow the cutting fluid 12 to be supplied to the layered bodies 25, so that the cutting fluid 12 can sufficiently modify the metal contained in the layered bodies 25 to reduce the metal's ductility as the cutting blade 8 cuts the layered bodies 25. Consequently, the metal is prevented from forming burrs, even when the workpiece is machined at an increased speed. In other words, the speed at which the workpiece 11 is machined can be increased while maintaining the quality of the machining of the workpiece 11.

[0050] The present invention is not limited to the embodiment described above, but various changes and modifications can be made to it. For example, in the cutting step according to the embodiment described above, the surface 11a of the workpiece 11 is exposed upwards and the cutting blade 8 cuts into the workpiece 11 from the surface 11a. However, the rear side 11b of the workpiece 11 can also be exposed upwards and the cutting blade 8 can cut into the workpiece 11 from the rear side 11b in the cutting step.

[0051] In the cutting step according to the embodiment above, the workpiece 11 is also divided (separated) together with the layered bodies 25. However, at least the layered bodies 25 can be separated in the cutting step. In other words, the workpiece 11 does not necessarily have to be divided in the cutting step.

[0052] In the cutting step according to the embodiment above, the cutting blade 8, which has grooves 8d extending radially along its radial directions, is used. These grooves are formed in the surface face 8a and the rear face 8b of the outer circumferential section thereof. The grooves 8d are not limited to specific quantities, shapes, sizes, etc. For example, a cutting blade 8 having one or more grooves formed in the surface face 8a or the rear face 8b of the outer circumferential section thereof can be used.

[0053] Fig. Figure 3B is a front view schematically showing a cutting blade 8 according to one modification. The cutting blade 8, which is in Fig. As shown in Figure 3B, the cutting blade 8 has grooves 8e formed in one surface 8a and extending in a ring shape along its circumference. In this case, the cutting fluid 12 can also be efficiently supplied to the layered bodies 25 through the grooves 8e.

[0054] In the above cutting step, the cutting fluid 12 is supplied by the nozzles 10, which are arranged on both sides of the cutting blade 8. However, the present invention is not limited to a specific nozzle configuration for supplying the cutting fluid 12. Fig. Figure 4 is a front view of a nozzle for supplying the cutting fluid 12 according to another embodiment of the present invention. As in Fig. As shown in Figure 4, a cutting unit 6 includes, in addition to the cutting blade 8 and the pair of nozzles 10, a shower nozzle 14, which is arranged laterally to the cutting blade 8, i.e. in front of the cutting blade 8 with respect to the direction along which the cutting of the workpiece 11 by the cutting blade 8 proceeds.

[0055] The nozzle 14 facilitates the supply of the cutting fluid 12 to the joint (slot) 11c for more effective modification of the metal contained in the layered bodies 25. In particular, nozzle 14 has an outlet opening inclined downwards towards an area where the cutting blade 8 processes the workpiece 11, as shown in Fig. 4 shown, so that the joint 11c is supplied and filled with an increased amount of the cutting fluid 12 for more effective modification of the metal contained in the layered bodies 25. Although both nozzles 10 and nozzle 14 in Fig.If nozzles 4 are used, nozzles 10 can be omitted and only nozzle 14 can be used alone.

Claims

[1] Method for machining a plate-shaped workpiece (11) comprising layered bodies (25) containing metal formed in a superimposed relationship with projected division lines (19), comprising the following steps: Holding the workpiece (11) on a holding table; and then cutting the workpiece along the projected division lines (19) with a ring-shaped cutting blade (8), thereby dividing the layered bodies (25); wherein the cutting blade (8) has a groove (8d) formed in a surface side (8a) or a rear side (8b) of an outer circumferential section thereof, which cuts into the workpiece (11) in the step of cutting the workpiece (11); and The step of cutting the workpiece (11) includes the step of cutting the workpiece (11) while a cutting fluid (12) containing an organic acid and an oxidizing agent is supplied to the workpiece (11), wherein the holding table has a holding surface (4a) in which outlet grooves (4b) are arranged, dividing the holding surface (4a) into several areas according to the division lines (19), wherein the outlet grooves (4b) each have a width greater than the width of the cutting blade (8) and a depth greater than the distance by which the cutting blade (8) projects through the workpiece (11) towards the holding table when cutting through the workpiece (11). [2] Method according to claim 1, wherein the groove (8d) extends radially along a radial direction of the cutting blade (8). [3] Method according to claim 1, wherein the groove (8b) extends in a ring shape along a circumferential direction of the cutting blade (8).

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