Saw wire and cutting device

Abstract

To provide a saw wire having high adhesion to abrasive grains. [Solution] The saw wire 10 having a plurality of abrasive grains 130 attached to its surface comprises a metal wire 100 made of tungsten or a tungsten alloy, a nickel plating layer 110 provided on the surface of the metal wire 100, and an adhesion layer 120 of nickel and tungsten provided at the interface between the metal wire 100 and the nickel plating layer 110, and when the saw wire 10 is twisted, the nickel plating layer 110 is prevented from peeling off from the metal wire 100 by the adhesion layer 120.

Description

[Technical Field]

[0001] The present invention relates to a saw wire and a cutting device including the saw wire. [Background technology]

[0002] BACKGROUND ART Conventionally, a multi-wire saw that slices a silicon ingot using wires made of piano wires is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-213111 Summary of the Invention [Problem to be solved by the invention]

[0004] Wire saws produce shavings equal to the diameter of the wire. The conventional multi-wire saws described above use wires made of piano wire, but it is difficult to thin piano wire. Currently, it is difficult to manufacture piano wire with a diameter smaller than 60 μm. Furthermore, because the elastic modulus of piano wire is 150 GPa to 250 GPa, even if the diameter can be thinned, bending occurs during slicing. Therefore, thin piano wire is not suitable for slicing with a wire saw.

[0005] For this reason, it is conceivable to manufacture saw wire using a material other than piano wire. However, when the saw wire and abrasive grains are fixed to each other in advance as in the fixed abrasive grain method, if the adhesion between the saw wire and the abrasive grains is poor, the abrasive grains will fall off, resulting in a decrease in sharpness.

[0006] Therefore, an object of the present invention is to provide a saw wire that has high adhesion to abrasive grains and a cutting device that includes the saw wire. [Means for solving the problem]

[0007] In order to achieve the above object, a saw wire according to one embodiment of the present invention is a saw wire having a plurality of abrasive grains attached to its surface, and comprises a metal wire made of tungsten or a tungsten alloy, a nickel plating layer provided on the surface of the metal wire, and an adhesion layer of nickel and tungsten provided at the interface between the metal wire and the nickel plating layer, and the nickel plating layer is prevented from peeling off from the metal wire by the adhesion layer when the saw wire is twisted.

[0008] A cutting device according to one aspect of the present invention includes the saw wire. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a saw wire that has high adhesion to abrasive grains and a cutting device that includes the saw wire. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a cutting device according to an embodiment. [Figure 2] 3 is a cross-sectional view showing how an ingot is sliced ​​by the cutting device according to the embodiment. FIG. [Figure 3] FIG. 1 is a cross-sectional view of a saw wire according to an embodiment. [Figure 4] FIG. 1 is a state transition diagram showing a process of producing a thinned metal wire in a saw wire manufacturing method according to an embodiment. [Figure 5] FIG. 10 is a state transition diagram showing a step of fixing abrasive grains to a metal wire in the saw wire manufacturing method according to the embodiment. [Figure 6] FIG. 2 is a schematic diagram of a twisting device that twists a saw wire according to an embodiment. [Figure 7] FIG. 10 is a diagram showing the relationship between heating temperature in heat treatment and plating peeling in the saw wire according to the embodiment. [Figure 8] FIG. 10 is a diagram showing a twisted saw wire according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Below, a saw wire and a cutting device according to embodiments of the present invention will be described in detail with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component arrangements and connection forms, steps, and step orders shown in the following embodiments are examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concept of the present invention will be described as optional components.

[0012] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. Furthermore, in each figure, substantially the same components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0013] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel or equal, terms indicating the shape of elements, such as circular, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0014] (Embodiment) [Cutting device] First, an outline of a cutting device including a saw wire according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a perspective view of a cutting device 1 according to the present embodiment.

[0015] As shown in FIG. 1, the cutting device 1 is a multi-wire saw equipped with a saw wire 10. The cutting device 1 produces wafers, for example, by cutting an ingot 20 into thin plates. The ingot 20 is, for example, a silicon ingot made of single crystal silicon. Specifically, the cutting device 1 slices the ingot 20 with the saw wire 10 to simultaneously produce multiple silicon wafers.

[0016] The ingot 20 is not limited to a silicon ingot, but may be other ingots such as silicon carbide or sapphire, etc. Alternatively, the object to be cut by the cutting device 1 may be concrete, glass, or the like.

[0017] As shown in FIG. 1, the cutting device 1 further comprises two guide rollers 2, a support 3 and a tension relief device 4.

[0018] One saw wire 10 is wound multiple times around the two guide rollers 2. For convenience of explanation, one turn of the saw wire 10 is considered as one saw wire 10, and the following explanation will be given assuming that multiple saw wires 10 are wound around the two guide rollers 2. That is, in the following explanation, the multiple saw wires 10 form one continuous saw wire 10. Note that the multiple saw wires 10 may be individually separated saw wires.

[0019] The two guide rollers 2 rotate while tensioning the saw wires 10 straight with a predetermined tension, thereby rotating the saw wires 10 at a predetermined speed. The saw wires 10 are arranged parallel to each other and at equal intervals. Specifically, each of the two guide rollers 2 has a plurality of grooves at a predetermined pitch into which the saw wires 10 are inserted. The groove pitch is determined according to the thickness of the wafer to be cut out. The width of the groove is approximately the same as the wire diameter φ of the saw wire 10.

[0020] The tension relief device 4 is a device that relieves the tension applied to the saw wire 10. For example, the tension relief device 4 is an elastic body such as a helical spring or a leaf spring. As shown in FIG. 1 , the tension relief device 4, which is, for example, a helical spring, has one end connected to the guide roller 2 and the other end fixed to a predetermined wall surface. The tension relief device 4 adjusts the position of the guide roller 2, thereby allowing the tension applied to the saw wire 10 to be relieved.

[0021] The cutting device 1 may include three or more guide rollers 2. A plurality of saw wires 10 may be wound around the three or more guide rollers 2.

[0022] The support unit 3 supports an ingot 20, which is an object to be cut. The support unit 3 pushes the ingot 20 toward the plurality of saw wires 10, whereby the ingot 20 is sliced ​​by the plurality of saw wires 10.

[0023] Although not shown, the cutting device 1 may include a supply device that supplies cutting fluid such as coolant to the plurality of saw wires 10.

[0024] Fig. 2 is a cross-sectional view showing how an ingot 20 is sliced ​​by the cutting device 1 according to this embodiment. Fig. 2 is a cross-section taken along line II-II shown in Fig. 1, and shows a part of a cross-section perpendicular to the extending direction of the saw wire 10. Specifically, it shows how the ingot 20 is sliced ​​by three of the multiple saw wires 10.

[0025] By pushing the ingot 20 toward the multiple saw wires 10, the ingot 20 is simultaneously divided into multiple split pieces 21 by the multiple saw wires 10. Gaps 22 between adjacent split pieces 21 are spaces formed by the ingot 20 being scraped away by the saw wires 10. In other words, the size of the gaps 22 corresponds to the loss of the ingot 20.

[0026] The width d of the gap 22 depends on the wire diameter φ of the saw wire 10. That is, the larger the wire diameter φ of the saw wire 10, the larger the width d, and the greater the loss of the ingot 20. The smaller the wire diameter φ of the saw wire 10, the smaller the width d, and the less the loss of the ingot 20.

[0027] Specifically, the width d of the gap 22 is larger than the wire diameter φ. The difference between the width d and the wire diameter φ is a magnitude that depends on the size of the abrasive grains 130 fixed to the saw wire 10 and the amplitude of vibration when the saw wire 10 rotates. At this time, the amplitude of vibration of the saw wire 10 can be suppressed by tightening the tension of the saw wire 10. The higher the tensile strength and elastic modulus of the saw wire 10, the more tightly the saw wire 10 can be tensioned. Therefore, the amplitude of vibration of the saw wire 10 becomes smaller, and the width d of the gap 22 can be reduced, thereby further reducing loss of the ingot 20.

[0028] The thickness D of the divided pieces 21 depends on the spacing between the multiple saw wires 10. Therefore, the multiple saw wires 10 are arranged at spacings that are the desired thickness D plus a predetermined margin. Specifically, the margin is the difference between the width d and the wire diameter φ, and is a value that is determined depending on the oscillation width of the saw wire 10 and the grain size of the abrasive grains 130.

[0029] From the above, it can be seen that the wire diameter φ, tensile strength, and elastic modulus of the saw wire 10 are important parameters for reducing loss of the ingot 20. Specifically, the loss of the ingot 20 can be reduced by reducing the wire diameter φ of the saw wire 10 or by increasing the tensile strength and elastic modulus of the saw wire 10.

[0030] The configuration and manufacturing method of the saw wire 10 will be described below.

[0031] [Saw wire] Fig. 3 is a cross-sectional view of the saw wire 10 according to the present embodiment. Specifically, Fig. 3 is an enlarged view of a cross section perpendicular to the extending direction of the saw wire 10.

[0032] 3, the saw wire 10 includes a metal wire 100, a nickel plating layer 110, and an adhesion layer 120. Furthermore, the saw wire 10 includes a plurality of abrasive grains 130 attached to the surface. The wire diameter φ of the saw wire 10 is the sum of the wire diameter of the metal wire 100, the nickel plating layer 110, and the adhesion layer 120. The adhesion layer 120 is formed at the interface between the metal wire 100 and the nickel plating layer 110 with a predetermined thickness.

[0033] The metal wire 100 is an extremely thin metal wire made of tungsten (W). The metal wire 100 is made of pure tungsten. Specifically, the purity of the tungsten is 99.9% or more.

[0034] The smaller the wire diameter of the metal wire 100 made of tungsten, the stronger the tensile strength per cross-sectional area. That is, by using the metal wire 100 made of tungsten, it is possible to realize a saw wire 10 having a small wire diameter φ and high tensile strength, and it is possible to suppress loss of the ingot 20.

[0035] The metal wire 100 has a modulus of elasticity of 350 GPa or more and 450 GPa or less. The modulus of elasticity is the longitudinal modulus of elasticity. In other words, the metal wire 100 has a modulus of elasticity that is approximately twice that of a piano wire.

[0036] The diameter of the metal wire 100 is, for example, 80 μm or less. Note that the thinner the metal wire 100 made of tungsten, i.e., the smaller the wire diameter, the higher the strength per cross-sectional area. For example, the diameter of the metal wire 100 may be 50 μm or less, or 40 μm or less. As an example, the diameter of the metal wire 100 is 20 μm, but it may also be 10 μm. Note that when abrasive grains 130 are attached as in this embodiment, the diameter of the metal wire 100 is, for example, 10 μm or more.

[0037] The metal wire 100 has a uniform wire diameter. Since the wire diameter of the metal wire 100 is 80 μm or less, the metal wire 100 is flexible and can be bent easily. Therefore, the saw wire 10 can be easily wound between the guide rollers 2.

[0038] 3, the cross-sectional shape of the metal wire 100 is circular, but is not limited to this. The cross-sectional shape of the metal wire 100 may be rectangular, such as a square, or oval.

[0039] The tensile strength of the metal wire 100 is, for example, 3500 MPa or more. By reducing the wire diameter, the tensile strength of the metal wire 100 can be increased to, for example, 4000 MPa or more.

[0040] The nickel plating layer 110 is a plating layer provided on the surface of the metal wire 100. The nickel plating layer 110 is a thin film layer made of nickel (Ni). The thickness of the nickel plating layer 110 is, for example, 1 μm, but is not limited to this.

[0041] The nickel plating layer 110 closely covers at least a portion of the plurality of abrasive grains 130 and also entirely covers the surface of the metal wire 100 between the plurality of abrasive grains 130. Specifically, as shown in Fig. 3, the nickel plating layer 110 is provided in an annular shape around the entire circumference of the axis of the metal wire 100 in a cross-sectional view.

[0042] The plurality of abrasive grains 130 are hard particles, such as diamond or CBN (cubic boron nitride) particles. The average particle size of the plurality of abrasive grains 130 is, for example, 10 μm or less, but is not limited to this. At least a portion of the plurality of abrasive grains 130 is in close contact with the nickel plating layer 110, and thus adheres to the surface of the saw wire 10.

[0043] [Saw wire manufacturing method] The following describes a method for manufacturing the saw wire 10 having the above-mentioned characteristics. The method for manufacturing the saw wire 10 includes a step of producing a thinned metal wire 100 and a step of fixing a plurality of abrasive grains 130 to the metal wire 100.

[0044] First, the steps of producing the metal wire 100 will be described below with reference to Fig. 4. Fig. 4 is a transition diagram showing the steps of producing the thinned metal wire 100 in the method of producing the saw wire 10 according to the present embodiment.

[0045] First, as shown in Fig. 4(a), tungsten powder 101 is prepared. The average particle size of the tungsten powder 101 is, for example, 5 µm, but is not limited to this.

[0046] Next, the tungsten powder 101 is pressed and sintered to produce an ingot made of tungsten. The ingot is then subjected to a swaging process, which involves forging and compressing it from the periphery and then expanding it, to produce a wire-shaped tungsten wire 102, as shown in Figure 4(b). For example, the diameter of a sintered tungsten ingot is about 15 mm, while the diameter of the wire-shaped tungsten wire 102 is about 3 mm.

[0047] Next, as shown in FIG. 4(c), wire drawing is performed using a wire drawing die.

[0048] Specifically, first, as shown in (c1) of Fig. 4, the tungsten wire 102 is annealed. Specifically, the tungsten wire 102 is not only heated directly with a burner, but also heated while a current is passed through the tungsten wire 102. The annealing step is performed to remove processing strain caused by the swaging or wire drawing process.

[0049] Next, as shown in FIG. 4(c2), the tungsten wire 102 is drawn, i.e., drawn, using a wire drawing die 30. Note that the tungsten wire 102 is heated and softened by the previous annealing step, making it easy to draw. Thinning the tungsten wire 102 increases its strength per cross-sectional area. In other words, the tungsten wire 103 thinned by the wire drawing step has a higher strength per cross-sectional area than the tungsten wire 102. Note that the diameter of the tungsten wire 103 is, for example, 0.6 mm, but is not limited to this.

[0050] 4(c3), the drawn tungsten wire 103 is subjected to electrolytic polishing to smooth the surface of the tungsten wire 103. The electrolytic polishing step is performed by immersing the tungsten wire 103 and a counter electrode 41, such as a carbon rod, in an electrolyte 40, such as an aqueous sodium hydroxide solution, and then applying a current between the tungsten wire 103 and the counter electrode 41.

[0051] Next, as shown in (c4) of Fig. 4, the dies are replaced. Specifically, a wiredrawing die 31 having a smaller diameter than the wiredrawing die 30 is selected as the die to be used in the next wiredrawing process. The wiredrawing dies 30 and 31 are diamond dies made of, for example, sintered diamond or single crystal diamond.

[0052] Steps (c1) to (c4) in Fig. 4 are repeated until the diameter of the tungsten wire 103 reaches the desired diameter (specifically, 60 µm or less). At this time, the wire drawing step shown in Fig. 4 (c2) is performed by adjusting the shape and hardness of the wire drawing die 30 or 31, the lubricant used, the temperature of the tungsten wire, and the like, depending on the diameter of the target tungsten wire.

[0053] Similarly, in the annealing step shown in (c1) of Figure 4, the annealing conditions are adjusted according to the diameter of the tungsten wire. During the annealing step, oxides adhere to the surface of the tungsten wire. By adjusting the annealing conditions, the amount of oxides that adhere can be adjusted.

[0054] Specifically, the larger the diameter of the tungsten wire, the higher the annealing temperature, and the smaller the diameter of the tungsten wire, the lower the annealing temperature. For example, when the diameter of the tungsten wire is large, the annealing step in the first wiredrawing process is specifically performed at a temperature of 1400°C to 1800°C. In the final annealing step in the final wiredrawing process to obtain the desired wire diameter, the wire is heated at a temperature of 1200°C to 1500°C. Note that it is not necessary to energize the tungsten wire in the final annealing process.

[0055] Furthermore, when repeating the wiredrawing process, the annealing step may be omitted. For example, the final annealing step may be omitted. Specifically, the final annealing step may be omitted, and the lubricant and the shape and hardness of the wiredrawing die may be adjusted.

[0056] Furthermore, in the wire drawing process after the final annealing (i.e., the final wire drawing process), a single crystal diamond die made of single crystal diamond is used as the wire drawing die 31. Since diamond particles are less likely to detach from a single crystal diamond die, wire streaks are less likely to form in the tungsten wire after wire drawing. This allows the surface roughness Ra of the tungsten wire to be reduced when the wire diameter is reduced to the desired value.

[0057] Furthermore, when repeating the wiredrawing process, for example, the weight ratio of the oxide amount at 50 MG is set to 0.2% to 0.5%, and wiredrawing is started from a single crystal diamond die with a hole diameter of 200 μm. As a result, a metal wire 100 with a surface roughness Ra of 0.15 μm or less is produced, as shown in FIG. 4(d).

[0058] Next, a process of adhering a plurality of abrasive grains 130 to the metal wire 100 will be described with reference to Fig. 5. Fig. 5 is a state transition diagram showing a process of adhering abrasive grains 130 to the metal wire 100 in the manufacturing method of the saw wire 10 according to the present embodiment. Note that Fig. 5(e) shows a part of the plating solution 50, and Fig. 5(f) and (g) show a schematic enlarged view of the surface layer portion of the metal wire 100.

[0059] First, a nickel plating layer 110 is formed on the surface of the metal wire 100, and abrasive grains 130 are electrodeposited. Specifically, as shown in FIG. 5(e), a nickel plate 51 and the metal wire 100 are immersed in a plating solution 50, and an electric current is passed between the nickel plate 51 and the metal wire 100. The plating solution 50 is a liquid containing nickel sulfate, nickel chloride, and boric acid. In this embodiment, a plurality of abrasive grains 130 are dispersed and mixed in the plating solution 50. As a result, a plurality of abrasive grains 130 are electrodeposited on the surface of the metal wire 100, and further, a nickel plating layer 110 is formed so as to fill the gaps between the abrasive grains 130, as shown in FIG. 5(f).

[0060] Next, as shown in (f) of Fig. 5, the metal wire 100 on which the nickel plating layer 110 has been formed is subjected to a heat treatment. The heat treatment forms an adhesion layer 120. Note that before the heat treatment, i.e., immediately after the nickel plating layer 110 has been formed, the adhesion layer 120 has not been formed, as shown in the enlarged view of (f) of Fig. 5.

[0061] The heat treatment is performed at a temperature of, for example, 650°C. If the temperature is too low, the adhesion layer 120 will not be formed. If the temperature is too high, the strength of the metal wire 100 will decrease. For this reason, the heat treatment is performed at a temperature in the range of, for example, more than 450°C and not more than 850°C.

[0062] The heat treatment time is, for example, 1 to 5 seconds. When the abrasive grains 130 are diamond particles, the heat treatment is carried out in an oxygen-free atmosphere such as an argon atmosphere to prevent oxidation of the diamond.

[0063] Through the above steps, the saw wire 10 is manufactured as shown in FIG. 5(g).

[0064] By carrying out heat treatment after nickel plating and electrodeposition, the adhesive strength between the metal wire 100 and the nickel plating layer 110 is increased.

[0065] 4 and 5 each schematically show each step of the manufacturing method of the saw wire 10. Each step may be performed individually, or each step may be performed inline. For example, a plurality of wiredrawing dies may be arranged on a production line in order of decreasing diameter, and a heating device for performing an annealing step may be disposed between each wiredrawing die. Furthermore, an electrolytic polishing device, a plating device, and a heating device may be disposed in this order after the wiredrawing die with the smallest diameter.

[0066] [Relationship between heat treatment and plating peeling] Here, the relationship between the temperature of the heat treatment after the nickel plating layer 110 is formed and the detachment (peeling off) of the nickel plating layer 110 will be described.

[0067] Here, it was observed whether or not plating peeling occurs by twisting the saw wire 10 multiple times using a twisting device 200 shown in Fig. 6. Fig. 6 is a schematic diagram of the twisting device 200 that applies a twist to the saw wire 10 according to the present embodiment.

[0068] In the twisting device 200 shown in Fig. 6, the hook portion 210 is a portion on which the saw wire 10 is hooked, and is connected to the handle 230 via a cylindrical rotating body 220. The rotating body 220 is rotatably supported on a support base 240, and rotates in response to the rotation of the handle 230. The hook portion 210 also rotates in response to the rotation of the rotating body 220. For example, the number of rotations of the handle 230 and the number of rotations of the hook portion 210 are the same.

[0069] First, a plurality of saw wires 10 with different heat treatment temperatures were prepared as twisting targets. Specifically, seven types of saw wires 10 with heat treatment temperatures between 250°C and 850°C in increments of 100°C were prepared.

[0070] The prepared saw wire 10 was cut to a length of 60 mm and then bent in half to form a U-shape. As shown in Fig. 6, the bent portion of the saw wire 10 was hooked onto a hook portion 210 of a twisting device 200, and then the saw wire 10 was gripped at a position 10 mm from the end and pulled in the opposite direction from the hook portion 210 with a force of 5 N. Furthermore, while pulling the saw wire 10, the handle 230 was turned to rotate the hook portion 210 a predetermined number of times. Thereafter, the twisted saw wire 10 was observed under a microscope to evaluate the presence or absence of plating peeling.

[0071] Fig. 7 is a diagram showing the relationship between the heating temperature in the heat treatment and peeling of plating in the saw wire 10. Fig. 7 shows whether or not peeling of plating occurs when the number of twists is 40 and the rotation speed of twisting is 1 rotation / second.

[0072] As shown in Fig. 7, when the heating temperatures were 250°C, 350°C, and 450°C, plating peeling occurred as shown in Fig. 8. Here, Fig. 8 is a diagram showing a twisted saw wire 10. In Fig. 8, peeling of the nickel plating layer 110 can be visually confirmed in the area surrounded by a thick dashed line. It was confirmed that the lower the heating temperature, the greater the amount of detachment of the nickel plating layer 110.

[0073] On the other hand, as shown in Fig. 7, no plating peeling was observed when the heating temperatures were 550°C, 650°C, 750°C, and 850°C. From the above, it can be seen that the nickel plating layer 110 peels off when the heating temperature is 450°C or less, whereas the nickel plating layer 110 does not peel off when the heating temperature is 550°C or more.

[0074] If the heating temperature is too high, the tensile strength of the saw wire 10 decreases. Specifically, the tensile strength of the saw wire 10 heated at 750°C was lower than the tensile strength of the saw wire 10 heated at 650°C. For this reason, it is not preferable that the heating temperature is too high, and the heating temperature is, for example, a temperature of 850°C or lower.

[0075] [Effects, etc.] As described above, the saw wire 10 according to the present embodiment is a saw wire having a plurality of abrasive grains 130 attached to its surface, and includes a metal wire 100 made of tungsten, a nickel plating layer 110 provided on the surface of the metal wire 100, and an adhesion layer 120 of nickel and tungsten provided at the interface between the metal wire 100 and the nickel plating layer 110, and when the saw wire 10 is twisted, the nickel plating layer 110 is prevented from peeling off from the metal wire 100 by the adhesion layer 120. Furthermore, for example, the wire diameter of the metal wire 100 is 80 μm or less.

[0076] As a result, since the metal wire 100 contains tungsten as a main component, the thinner the wire, the greater the tensile strength per cross-sectional area, making it less likely to break. Therefore, the saw wire 10 can be stretched between the guide rollers 2 with strong tension, which makes it possible to suppress vibration of the saw wire 10 when cutting the ingot 20. Therefore, it is possible to reduce shavings generated when slicing the ingot 20, i.e., loss of the ingot 20.

[0077] In this embodiment, the adhesion layer 120 is provided between the metal wire 100 and the nickel plating layer 110, thereby increasing the adhesion between the metal wire 100 and the nickel plating layer 110. This can increase the adhesion between the abrasive grains 130 covered with the nickel plating layer 110 and the metal wire 100. This suppresses detachment of the abrasive grains 130. Furthermore, the high adhesion between the metal wire 100 and the nickel plating layer 110 also suppresses peeling of the nickel plating layer 110 together with the abrasive grains 130. This can suppress deterioration in the sharpness of the saw wire 10.

[0078] The cutting device 1 according to this embodiment also includes a saw wire 10.

[0079] This reduces the wire diameter of the saw wire 10, allowing an increase in the number of wafers cut out from one ingot 20. Also, it is possible to reduce the amount of shavings generated when slicing the ingot 20. This allows for effective use of limited resources such as the material of the ingot 20. Furthermore, it is possible to suppress deterioration in the sharpness of the saw wire 10, allowing the ingot 20 to be sliced ​​with high precision.

[0080] (others) Although the saw wire and the cutting device according to the present invention have been described based on the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment.

[0081] For example, although the above embodiment has been described with reference to an example in which the metal wire 100 is made of pure tungsten, the present invention is not limited to this. The metal wire 100 may be made of an alloy of rhenium (Re) and tungsten (ReW).

[0082] Specifically, the metal wire 100 may contain tungsten as a main component and a predetermined proportion of rhenium. The rhenium content of the metal wire 100 is, for example, 0.1 wt% or more and 10 wt% or less. Specifically, the rhenium content is 3 wt%, but may be 1 wt%.

[0083] The metal wire 100 contains rhenium, which makes it stronger than a pure tungsten wire. For example, the tensile strength of a ReW wire is 3500 MPa or more and 6000 MPa or less. This makes the metal wire 100 less likely to break even when thinned, and it is possible to achieve a tensile strength equal to or greater than that of a piano wire.

[0084] Therefore, the saw wire 10 can be more tightly stretched between the two guide rollers 2, which further reduces vibration of the saw wire 10. As a result, loss of the ingot 20 can be further reduced.

[0085] Furthermore, for example, the saw wire 10 may include a metal wire made of tungsten doped with potassium (K) (hereinafter referred to as potassium-doped tungsten wire) instead of the metal wire 100 made of pure tungsten or a ReW alloy.

[0086] The potassium-doped tungsten wire contains tungsten as a main component and a predetermined amount of potassium, the potassium content of which is 0.005 wt% or more and 0.010 wt% or less.

[0087] The smaller the wire diameter φ of the potassium-doped tungsten wire, the stronger the tensile strength per cross-sectional area. In other words, by using a potassium-doped tungsten wire, a saw wire with a small wire diameter φ and high tensile strength can be realized, and loss of the ingot 20 can be suppressed.

[0088] The tensile strength, elastic modulus, wire diameter φ, etc. of the potassium-doped tungsten wire are the same as those of the metal wire 100 made of a ReW alloy.

[0089] As a result, the small amount of potassium contained in the tungsten suppresses the radial grain growth of the potassium-doped tungsten wire, and therefore the saw wire including the potassium-doped tungsten wire has higher strength at high temperatures than pure tungsten.

[0090] Furthermore, for example, in the above embodiment, the electrodeposition of the abrasive grains 130 and the formation of the nickel plating layer 110 are performed simultaneously, but this is not limiting. Either the electrodeposition or the plating process may be performed first.

[0091] Furthermore, for example, the cutting device 1 does not have to be a multi-wire saw, and may be a wire saw device that slices the ingot 20 with one saw wire 10 to cut out wafers one by one.

[0092] In addition, the present invention also includes forms obtained by applying various modifications to each embodiment that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope of the present invention. [Explanation of symbols]

[0093] 1 cutting device 10 Saw Wire 100 Metal Wire 110 Nickel plating layer 120 Adhesion layer 130 diamond particles (abrasive grains)

Claims

1. A saw wire having a plurality of abrasive grains attached to its surface, a metal wire made of tungsten or a tungsten alloy; a nickel plating layer provided on the surface of the metal wire; an adhesion layer of nickel and tungsten provided at the interface between the metal wire and the nickel plating layer, The nickel plating layer does not peel off from the metal wire due to the adhesion layer when the saw wire is twisted. Saw wire.

2. The adhesive layer is formed on the entire surface of the metal wire. The saw wire according to claim 1.

3. The diameter of the metal wire is 80 μm or less. The saw wire according to claim 1 or 2.

4. The tensile strength of the metal wire is 3500 MPa or more. The saw wire according to any one of claims 1 to 3.

5. The tungsten alloy is an alloy of rhenium and tungsten, The rhenium content of the tungsten alloy is 0.1 wt% or more and 10 wt% or less. The saw wire according to any one of claims 1 to 4.

6. A cutting device comprising the saw wire according to any one of claims 1 to 5.

Images