TW201442808A - Method for designing resin-coated saw wire - Google Patents

Abstract

Provided is a method for designing a resin-coated saw wire such that when a workpiece is cut off using a resin-coated saw wire formed by coating the surface of a steel wire with resin, the depth of a machining-altered layer is shallow, and a cut body having a smooth surface can be obtained. (1) A steel wire is coated with resin having predetermined hardness. (2) A workpiece is cut off using the resin-coated saw wire obtained. (3) The depth of the machining-altered layer on the cut crosses section of the workpiece is examined. (4) Acceptance or rejection of the depth of the machining-altered layer is checked. (5) In the event of rejection, a steel wire is coated with further hardened resin, and items (2) to (5) are repeated, and thereby, resin hardness is adjusted so that the depth of the machining-altered layer on the cut cross section of the workpiece will be accepted.

Description

Design method of resin coated wire saw

The present invention relates to a wire saw used for cutting a workpiece such as a wafer or a ceramic by a sawing machine, and more particularly to a method of designing a resin-coated wire saw in which a resin is coated on a surface of a steel wire.

A workpiece such as tantalum or ceramic is cut by a sawing machine equipped with a wire saw. The wire saw can travel in one or two directions (back and forth direction) and slice the workpiece to any width by contacting the workpiece with the wire saw.

When the workpiece is cut, a method of cutting a workpiece by spraying a slurry containing abrasive grains (hereinafter sometimes referred to as free abrasive grains) on a workpiece (a conventional method 1), and attaching and fixing the abrasive grains to the metal wire A method of cutting a workpiece with a wire saw with a fixed abrasive grain attached to the surface (conventional method 2) is known. In the former method, the free abrasive grains contained in the sprayed slurry are introduced between the workpiece and the wire saw, and the wire saw and the workpiece are abraded to promote the cutting of the workpiece, thereby cutting the workpiece. On the other hand, in the latter method, by grinding the particles fixed on the surface, the abrasion of the workpiece is promoted to facilitate the cutting of the workpiece, and thereby the workpiece is cut.

Further, Patent Document 1 discloses that the use of the abrasive particles to hold the resin is A method in which a wire saw with an outer peripheral surface of a steel wire such as a high carbon steel is coated with a film to cut a workpiece while embedding a solution containing free abrasive grains (conventional method 3).

The cut body obtained by cutting the crucible with a wire saw is used, for example, as a substrate of a solar cell. On the cut surface of the cut body, a work-affected layer (sometimes referred to as a damaged layer) is formed at the time of cutting. When the work-affected layer is left, it is pointed out that the bonding quality to the substrate is deteriorated, and the characteristics of the solar cell are not sufficiently obtained (Patent Document 2). Therefore, the work-affected layer needs to be removed.

Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-179677

Patent Document 2: Japanese Laid-Open Patent Publication No. 2000-323736

Fig. 1 is a view showing a state in which a steel wire is used as a wire saw in the same manner as in the above-described conventional method, and the free abrasive grains are sprayed on a steel wire and introduced into the abrasive grains. According to the study by the present inventors, it has been found that in this method, since the abrasive is introduced in the direction in which the steel wire is cut into the workpiece, and the abrasive is introduced between the steel wire and the cut surface (work wall surface) of the workpiece, the workpiece is The cut surface is also subjected to a grinding process to form a work-affected layer. Further, it was found that the surface roughness of the cut surface was also coarse.

Fig. 2 is a view showing the state in which the fixed abrasive grains are fixed to the surface of the wire saw or the workpiece is cut while the abrasive grains are buried, as shown in the above-mentioned conventional methods 2 and 3. According to the research of the present inventors, it can be known that these methods are the same as described above. Similarly to the first drawing, the cut surface (work wall surface) of the workpiece is also subjected to a grinding process to form a deeper work-affected layer.

As shown in the above-mentioned first and second drawings, in the conventional method, since the work-affected layer is formed on the cut surface of the cut body, as described in the above-mentioned Patent Document 2, it is necessary to remove the step on the downstream side. Processing the metamorphic layer. If the process of removing the altered layer can be omitted, the yield and productivity of the cut body can be improved.

Further, in addition to the work-affected layer formed on the cut surface, the cut surface is formed into irregularities due to the abrasive grains used at the time of cutting. However, smoothing is usually required for the surface of the cut body, so etching is applied in the step on the downstream side. If the etching step can be omitted, the productivity of the cut body can be improved.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a process for cutting a workpiece with a resin-coated wire saw covered with a resin wire surface to have a shallow depth and a smooth surface. The design method of the resin coated wire saw.

The present invention encompasses the following forms.

[1] A method for designing a resin-coated wire saw, which is a method for designing a resin-coated wire saw comprising a step of coating a steel wire with a resin having a predetermined hardness to obtain a resin-coated wire saw, characterized in that the method is repeated by repeating (1) to (4), the hardness of the resin is adjusted in such a manner that the depth of the work-affected layer on the cut surface of the workpiece is acceptable; (1) The workpiece is cut by the obtained resin-coated wire saw, (2) the depth of the affected layer on the cut surface of the workpiece is investigated, (3) the depth of the affected layer is confirmed to be acceptable, and (4) when the film is unqualified, A harder resin to coat the steel wire.

The basis of the above-mentioned pass or fail is only required to be the depth of the work-affected layer which can obtain the effect of the present invention. For example, as described later, the depth of the process-deteriorated layer is 5 μm or less as a criterion for pass or fail.

[2] The method of designing a resin-coated wire saw according to [1], wherein the steel layer is coated with a harder resin when the depth of the worked-modified layer is deeper than 5 μm.

[3] A method of designing a resin-coated wire saw, which is a method of designing a resin-coated wire saw comprising a step of coating a steel wire with a resin having a predetermined hardness to obtain a resin-coated wire saw, characterized in that it is carried out by repeating (1) to (4), the hardness of the resin is adjusted so that the surface roughness of the cut surface of the workpiece is acceptable; (1) the workpiece is cut by the obtained resin-coated wire saw, and (2) the workpiece is inspected. The surface roughness on the cut surface, (3) confirming whether the surface roughness is acceptable, and (4) when the film is unacceptable, the steel wire is coated with a harder resin.

The basis of the above-mentioned pass or fail is only a surface roughness which can obtain the effect of the present invention. For example, as described later, a surface roughness of 0.5 μm or less is used as a criterion for pass or fail.

[4] The method for designing a resin-coated wire saw according to [3], wherein the surface roughness is thicker than 0.5 μm, and the steel is coated with a harder resin. line.

[5] The method for designing a resin-coated wire saw according to any one of [1] to [4] wherein the resin has a film thickness of 2 to 15 μm.

[6] The method of designing a resin-coated wire saw according to any one of [1] to [5] wherein the steel wire has a wire diameter of 130 μm or less.

[7] A method for producing a cut body, comprising: cutting a workpiece by a resin-coated wire saw to produce a cut body, comprising: spraying abrasive grains on a resin adjusted in hardness; a step of coating the wire saw with a resin of the steel wire; and suppressing the introduction of the abrasive grains between the cut surface and the resin-coated wire saw by the resin, and introducing the abrasive grains along the covered wire saw in the cutting direction of the workpiece The step of cutting the workpiece.

[8] The method for producing a cut body according to [7], wherein the depth of the work-affected layer on the cut surface of the workpiece is 5 μm or less.

[9] The method for producing a cut body according to [7], wherein the surface roughness of the cut surface of the workpiece is 0.5 μm or less.

[10] The method for producing a cut body according to any one of [7], wherein the cutting amount of the workpiece is 1 to 1.1 times the wire diameter of the resin-coated wire saw. The method is cut off.

[11] The method for producing a cut body according to any one of [7] to [10] wherein the diamond abrasive grains are discharged as the abrasive grains.

[12] The method for producing a cut body according to any one of [7] to [11] wherein the resin is used at a temperature of 120 ° C and has a hardness of 0.07 GPa or more.

[13] A cutting body characterized by: any one of [7] to [12] The method for producing the cut body described above is produced.

[14] A resin-coated wire saw, which is characterized in that the method for producing a cut body according to any one of [7] to [12].

According to the present invention, the surface of the wire saw is covered with a resin and the hardness is adjusted. Therefore, it is possible to suppress the introduction of the abrasive grains between the cut surface and the resin-coated wire saw by the resin while introducing the abrasive grains and cutting them. This can suppress the formation of the work-affected layer on the surface of the cut body. Further, when the resin is covered with a wire saw to cut the workpiece, a cut body having a smooth surface can be produced. Therefore, in the step of the downstream side, the step of removing the affected layer or the etching step for smoothing the surface can be omitted, and the productivity of the cut body can be improved.

Further, when the wire saw is coated with the resin of the present invention, the abrasive grains can be prevented from being introduced between the cut surface and the resin-coated wire saw, so that the amount of cut can be reduced and the productivity of the cut body can be improved.

Fig. 1 is a schematic view showing a state in which a workpiece is cut by a steel wire.

Fig. 2 is a schematic view showing a state in which a workpiece is cut by a steel wire with fixed abrasive grains.

Fig. 3 is a schematic view showing a state in which a workpiece is cut by a resin-coated wire saw.

Fig. 4 is a cross-sectional view of the surface of the resin-coated wire saw (Comparative Example) after the workpiece of No. 32 of the second table was cut.

Fig. 5 (a) and (b) are cross-sectional views for explaining the steps of measuring the depth of the affected layer.

Fig. 6 is a cross-sectional view of the cut surface of the workpiece No. 25 of the second table taken with an optical microscope.

Fig. 7 is a cross-sectional view of the cut surface of the workpiece No. 27 of the second table taken with an optical microscope.

Fig. 8 is a cross-sectional view of the cut surface of the workpiece No. 32 of the second table taken with an optical microscope.

Fig. 9 is a plan view instead of a photograph of a cut surface of a workpiece No. 33 of the second table taken with an optical microscope.

Fig. 10 is a cross-sectional view of the cut surface of the workpiece No. 35 of the second table taken with an optical microscope.

Fig. 11 is a cross-sectional view of the cut surface of the workpiece No. 37 of the second table taken with an optical microscope.

Fig. 12 is a graph showing the relationship between the hardness of the resin measured at 120 ° C and the number of abrasive grains bitten on the surface of the resin.

Fig. 13 is a graph showing the relationship between the hardness of the resin measured at 120 ° C and the depth of the worked-affected layer formed on the cut surface.

As shown in the above first and second figures, when a steel wire or a steel wire with a fixed abrasive grain is used, and the workpiece is cut while the abrasive grain is sprayed on the wire saw, the cut surface of the workpiece is formed. The deteriorated layer is processed deep, and the surface roughness of the cut surface becomes thick.

On the other hand, when the wire saw is coated with a resin, the work-affected layer can be made shallow and the surface can be smooth. Use Fig. 3 to explain how the workpiece is cut by a resin-coated wire saw. As shown in Fig. 3, in the resin-coated wire saw of the present invention, a resin is formed on the surface, and when the workpiece is cut, the resin on the surface is adhered to the cut surface to prevent the abrasive grains from being introduced into the wire saw. Between the cut surface of the workpiece. Therefore, it is difficult to form a work-affected layer on the cut surface, and the surface of the cut surface is likely to be smooth.

When the resin coated on the surface of the steel wire is relatively soft, as in the above-described conventional method 3, the abrasive grains are bitten into the resin, and as shown in Fig. 2 above, the abrasive grains are interposed between the resin-coated wire saw and the workpiece, On the cut surface, a work-affected layer is formed.

Therefore, the inventors of the present invention have found that by appropriately adjusting the hardness of the resin coated on the surface of the steel wire, the abrasive grains are prevented from being bitten into the surface of the resin, and when the workpiece is cut by the resin-coated wire saw, the cutting can be performed. The depth of the work-affected layer formed on the cross section becomes shallow, and the surface roughness of the cut surface is lowered, thus completing the present invention. Specifically, it is a method of designing a resin-coated wire saw, and is a method of designing a resin-coated wire saw including a step of coating a steel wire with a resin having a predetermined hardness to obtain a resin-coated wire saw, and repeating the following by 1)~(4), the hardness of the resin is adjusted so that the depth of the work-affected layer on the cut surface of the workpiece is acceptable.

(1) The workpiece is cut by the obtained resin-coated wire saw.

(2) Investigate the surface properties (machining layer depth and surface roughness) of the cut surface of the workpiece.

(3) Confirm that the depth of the affected metamorphic layer is acceptable.

(4) When it is unqualified, the steel wire is coated with a harder resin.

When the surface of the cut surface was cut by a resin-coated wire saw, the surface property of the cut surface was examined. When the characteristic was unacceptable, the resin was coated on the surface of the steel wire to form a resin-coated wire saw. In this way, the surface properties of the cut surface can be made good.

When a wire saw is used to adjust the surface hardness to a proper surface hardness, while the abrasive grain is sprayed on the wire saw to cut the workpiece, as shown in Fig. 3, the abrasive grains are cut into the workpiece along the resin-coated wire saw. Although the direction is introduced, the resin is prevented from being introduced between the cut surface and the resin-coated wire saw by the resin. Therefore, the cut surface is hardly formed on the cut surface of the workpiece, and the cut surface is smooth.

In the surface properties, the depth of the work-affected layer is 5 μm or less (preferably 4 μm or less, preferably 3 μm or less) or the surface roughness (arithmetic average roughness Ra) is 0.5 μm or less (preferably 0.4 μm or less, particularly preferably It is desirable to design a resin-coated wire saw in a manner of 0.3 μm or less. The cut body cut by the resin-coated wire saw designed as described above can be suitably used as a material for a solar cell, for example.

By processing the depth of the deteriorated layer, the cut surface can be etched, and the depth of the etch pit introduced during the cutting of the workpiece can be measured.

For the surface roughness, the arithmetic mean roughness Ra can be measured using "CS-3200 (device name)" manufactured by Mitsutoyo Co., Ltd.

Next, a resin-coated wire saw which can be suitably used in the present invention will be described.

The resin-coated wire saw used in the present invention is a resin which is coated on the surface of a steel wire in accordance with the above-described policy.

The steel wire is preferably a steel wire having a tensile strength of 3,000 MPa or more. For a steel wire having a tensile strength of 3,000 MPa or more, for example, a high carbon steel wire containing 0.5 to 1.2% of C can be used. For the high carbon steel wire, for example, a piano wire specified in JIS G3502 can be used. The upper limit of the tensile strength of the above-mentioned steel wire is preferably 5000 MPa in consideration of the fact that it is not ductile and is likely to be broken when an abnormality such as a jumper is abnormal.

The diameter of the above-mentioned steel wire can be as small as possible within a range that can withstand the load given during cutting, and is, for example, 130 μm or less, preferably 110 μm or less, and particularly preferably 100 μm or less. By reducing the diameter of the steel wire, the amount of cut can be reduced to improve the productivity of the cut body. Further, the diameter of the steel wire is preferably set to 60 μm or more.

As the resin, a thermosetting resin or a thermoplastic resin can be used. In the above resin, a phenol resin, a guanamine resin, a quinone imide resin, a polyamidimide, an epoxy resin, or a polyamine can be suitably used. Carbamate, formaldehyde, ABS resin, vinyl chloride, polyester, and the like. In particular, polyamidolimine, polyurethane, or polyester can be suitably used.

The above resin can be formed by applying a commercially available varnish to the surface of the steel wire and heating it.

As the varnish, a varnish for enameled wire sold by Dongte Paint Co., Ltd. or a varnish for electric wires sold by Kyocera Chemical Co., Ltd., or the like can be used.

As the varnish for the enamel wire, for example, the following one can be used. .

(a) Polyurethane varnish ("TPU F1", "TPU F2-NC", "TPU F2-NCA", "TPU 6200", "TPU 5100", "TPU 5200", "TPU 5700", "TPU K5 132", "TPU 3000K", "TPU 3000EA", etc.;

(b) Polyester varnish ("LITON 2100S", "LITON 2100P", "LITON 3100F", "LITON 3200BF", "LITON 3300", "LITON 3300KF", "LITON 3500SLD", "Neoheat 8200K2", etc.; Paint Co., Ltd. products)

(c) Polyamidamine varnish ("Neoheat AI-00C", etc.; manufactured by Dongte Paint Co., Ltd.)

(d) polyester bismuth varnish ("Neoheat 8600A", "Neoheat 8600AY", "Neoheat 8600", "Neoheat 8600H3", "Neoheat 8625", "Neoheat 8600E2", etc.; )

For the varnish for electric wires, for example, a varnish for heat-resistant urethane copper wire ("EVE5160-27" or the like, an epoxy resin modified with epoxy resin), a varnish for formaldehyde copper wire ("TVE5225A", etc., polyvinyl formaldehyde) can be used. Resin), heat-resistant formaldehyde copper wire varnish ("TVE5230-27", epoxy modified formaldehyde resin), polyester copper wire varnish ("TVE5350 series", etc., polyester resin), etc. (all are Kyocera Chemical) Commodities made by a company limited by shares).

After applying the varnish to the surface of the steel wire, for example, it is thermally cured at 250 ° C or higher (preferably 300 ° C or higher) to coat the surface of the steel wire with a resin. The upper limit of the above-mentioned thermal hardening is preferably 400 ° C in consideration of the fact that the strength of the steel wire starts to decrease. The hardness of the above resin can be adjusted, for example, by changing the kind of the resin to be coated or the heating temperature at the time of forming the resin.

The resin is preferably a resin having a hardness of 0.07 GPa or more when measured at 120 °C. That is, when the workpiece is cut by the resin-coated wire saw, for example, the wire saw is traveled at a line speed of 500 m/min, and the wire saw is cut off while the wire saw is in contact with the abrasive or the wire saw. Therefore, the surface of the workpiece will rise in temperature due to frictional heat and may exceed 100 °C. When the hardness of the above resin is adjusted in accordance with the hardness measured at 100 ° C or lower (for example, room temperature), the friction heat generated during the cutting of the workpiece may not be able to withstand the softening of the resin. When the resin is softened, the abrasive grains are easily bitten into the resin, which may increase the depth of the work-affected layer and the surface becomes thick.

Therefore, the hardness of the above resin is adjusted so as not to soften even when friction heat is generated when the workpiece is cut, and is determined by hardness measured at a temperature exceeding 100 ° C (for example, 120 ° C). Specifically, the resin is preferably a resin having a hardness of 0.07 GPa or more when measured at 120 ° C, and particularly preferably a resin having 0.1 GPa or more. By using a resin having a hardness of 0.07 GPa or more as measured at 120 ° C, the number of abrasive grains biting on the surface of the resin can be suppressed to 20 / (50 μ m × 200 μ m) or less, and the formation is reduced. The body of the broken body processes the depth of the deteriorated layer and smoothes the surface of the cut body. The hardness of the resin is preferably as hard as possible, and the upper limit is not particularly limited.

The hardness of the above resin can be measured, for example, by a nanoindentation analysis method.

The film thickness of the above resin can be, for example, 2 to 15 μm. When the resin is too thin, there is a fear that it is difficult to uniformly form the resin on the surface of the steel wire. Further, when the resin is too thin, the resin is abraded in the initial stage of cutting, and the plain wire (steel wire) is exposed, which causes abrasion of the plain wire and has a fear of being easily broken. Therefore, the film thickness of the resin is preferably 2 μm or more, more preferably 3 μm or more, and particularly preferably 4 μm or more. However, when the resin is too thick, the diameter of the resin-coated wire saw increases, and the amount of cut is increased to cause a problem of deterioration in productivity. Further, the ratio of the resin to the entire resin-coated wire saw is too large, and the strength of the entire resin-coated wire saw is lowered. Thus, when it is desired to improve the productivity and increase the wire speed of the wire saw, there is a tendency to be easily broken. Therefore, the film thickness of the resin is preferably 15 μm or less, particularly preferably 13 μm or less, and particularly preferably 10 μm or less. Further, the upper limit and the lower limit of the film thickness of the above resin may be arbitrarily combined to constitute the range of the resin film thickness.

The diameter (wire diameter) of the resin-coated wire saw is not particularly limited, and is usually about 100 to 300 μm (preferably 100 to 150 μm).

As the workpiece to be cut by the resin-coated wire saw, for example, tantalum, ceramic, crystal, a semiconductor member, a magnetic material, or the like can be used.

Next, the conditions when the workpiece is cut by the above-described resin-coated wire saw to produce a cut body will be described.

When the workpiece is cut by the above-described resin-coated wire saw, the abrasive grains are sprayed on the wire saw and the workpiece is cut. As the abrasive grains, for example, cerium carbide abrasive grains (SiC) abrasive grains or diamond abrasive grains or the like can be used. In order to smooth the cut surface, it is particularly preferable to use diamond abrasive grains.

For the above-mentioned diamond abrasive grains, for example, "SMC Fine Dia (trade name)" manufactured by Sumiseki Materials Co., Ltd. can be used. The diamond abrasive grains may be of a polymorph type or a single crystal type, but it is preferred to use a single crystal type. This is because the single crystal type is not easily broken during cutting.

The average particle diameter of the above abrasive grains is not particularly limited, and for example, it may be 2~15μm (preferably 4~10μm, especially preferably 4~7μm).

The average particle diameter of the abrasive grains can be measured, for example, by "MicroTrack HRA (device name)" manufactured by Nikkiso Co., Ltd.

The above abrasive particles are usually sprayed with a slurry dispersed in a working fluid. A water-soluble working fluid or an oily working fluid can be used as the working fluid. As the water-soluble working fluid, a glycol-based working fluid "H4" manufactured by Yushiro Chemical Industry Co., Ltd., a propylene glycol-based working fluid "Histat TMD (trade name)" manufactured by Sanyo Chemical Industries Co., Ltd., or the like can be used. As the oily working fluid, Yushiro Chemical Industry Co., Ltd. "Yushiron Oil (trade name)" or the like can be used.

The concentration of the abrasive grains in the slurry may be, for example, 5 to 50% by mass (preferably 5 to 30% by mass, particularly preferably 5 to 10% by mass).

The temperature of the slurry is, for example, 10 to 30 ° C (preferably 20 to 25 ° C).

When the workpiece is cut by the above-described resin-coated wire saw, the cutting speed of the workpiece can be, for example, 0.1 to 0.8 mm/min (preferably 0.1 to 0.35 mm/min, and particularly preferably 0.25 to 0.35 mm/min). The wire speed of the resin-coated wire saw is set to 300 m/min or more (preferably 500 m/min or more, and more preferably 800 m/min or more).

In addition, the tension (N) applied to the resin-coated wire saw is preferably set so as to satisfy the range of the following formula (1) calculated from the tensile strength of the plain wire (the steel wire before coating the resin). In the following formula (1), it is assumed that the tensile strength of the steel wire is in the range of 50 to 70%, and the disconnection is not caused at the time of cutting, and it is set to "-5.0". Applied to the resin at break The total load after the cut-off load of the wire-drawing saw and the pull-out load applied when the resin-coated wire saw is pulled out from the workpiece is about 5.0 N in total.

Tension resistance × 0.5-5.0 ≦ tension ≦ tensile strength × 0.7-5.0. . . (1)

The tensile strength of the steel wire varies depending on the composition of the steel wire and the wire diameter. For example, when the piano wire (Class A) specified in JIS G3522 is used, the tensile strength of the steel wire having a wire diameter of 100 μm is 24.3 N, and the wire diameter is The tensile strength of the 120 μm steel wire is 34.4 N, and the tensile strength of the steel wire with a wire diameter of 130 μm is 39.7 N. When the piano wire (B type) is used, the steel wire with a wire diameter of 100 μm has a tensile strength of 26.5 N and a wire diameter of 120 μm. The tensile strength was 37.7 N, and the tensile strength of the steel wire having a wire diameter of 130 μm was 45.7 N.

When the workpiece is cut by the above-mentioned resin-coated wire saw, the amount of cut of the workpiece is about 1 to 1.1 times (preferably 1 to 1.05 times, more preferably 1) with respect to the wire diameter (diameter) of the resin-coated wire saw. ~1.04 times, more preferably 1~1.03 times). This improves the productivity of the cut body.

In other words, according to the resin-coated wire saw of the present invention, even if the abrasive grains are sprayed on the resin-coated wire saw by appropriately adjusting the hardness of the resin, the abrasive grains can be prevented from being introduced into the cut surface and the resin coating by the above resin. Between the wire saws, the amount of cut can be reduced.

On the other hand, as in the above-described conventional method 1, the amount of cut when the steel wire is used as the wire saw is a length which is about three times the average diameter of the abrasive grains and the width of the diameter of the steel wire. Therefore, in order to improve productivity, it is necessary to reduce the diameter of the steel wire, but there is a problem in that the strength is increased without breaking the steel wire. Limitations, therefore, there are restrictions on reducing the amount of cut.

Further, as in the above-described conventional method 3, when the abrasive grains are bitten into the resin film, the wire diameter (diameter) of the wire saw increases, so that the amount of cut of the workpiece also increases.

Further, as in the above-described conventional method 2, the amount of cut when the workpiece is cut using a steel wire with fixed abrasive grains is equal to the diameter of the steel wire with the fixed abrasive grains, and in order to improve productivity, it is considered to be reduced. The diameter of the steel wire is either reduced by the diameter of the fixed abrasive grain. However, when the diameter of the steel wire is excessively reduced, the strength becomes insufficient or cannot withstand the cutting load given at the time of cutting, and there is a concern that the wire is broken. Further, when the diameter of the fixed abrasive grains is reduced, the workpiece becomes less likely to be cut, resulting in deterioration of productivity.

The present invention will be more specifically described by the following examples, but the present invention is not limited to the embodiments described below, and may be appropriately modified and implemented within the scope of the gist of the present invention. Within the technical scope of the present invention.

Example

In the following Experimental Example 1, the amount of cut (cutting loss) when the workpiece was cut by a wire saw was produced, and in the following Experimental Example 2, the workpiece was cut by a wire saw. When the cut body is produced, the depth of the work-affected layer formed on the cut surface and the surface roughness are obtained.

[Experimental Example 1]

Mounting the workpiece (single crystal 矽) on the processing table and arranging the wire saw Above the workpiece, the processing table is lifted while the abrasive grains are sprayed on the wire saw, and the workpiece is cut by the wire saw while walking, and the amount of cutting (cutting loss) of the workpiece is measured.

The wire saw is a wire saw of the type shown in the first table below.

In No. 1 of the first table, the wire saw is a wire material specified in JIS G3522 (A type, a wire equivalent to "SWRS 82A". Specifically, C: 0.82% by mass, Si: 0.19) The mass %, Mn: 0.49 mass %, and the remainder is a wire composed of iron and unavoidable impurities) was drawn into a steel wire having a diameter of 120 μm.

In No. 2 of the first table below, the wire saw is a wire saw with a fixed abrasive grain attached thereto, that is, a piano wire used in the above No. 1 is drawn on the surface of a steel wire having a diameter of 120 μm. Ni plating was performed, and diamond abrasive grains having a maximum diameter of 17.5 μm were fixed to the Ni plating layer. The wire saw with fixed abrasive grains has a diameter of 155 μm.

Nos. 3 to 5 in the first table below are examples in which a resin-coated wire saw in which a resin is coated on the surface of a steel wire with a thickness shown in the following Table 1 is used as a wire saw.

In the steel wire No. 3 of the first table below, the steel wire used in the above No. 1 is drawn into a steel wire having a diameter of 120 μm, and the No. 1 in the following first table is used. The piano wire used was drawn into a steel wire having a diameter of 130 μm, and the piano wire used in the above No. 1 was drawn into a steel wire having a diameter of 110 μm in No. 5 of the following Table 1.

The above resin is formed by applying the following varnish to the surface of the steel wire and then curing it by heating. Specifically, before forming the resin, After the steel wire is subjected to degreasing treatment, the following varnish is applied by dividing the number of times of application into 4 to 10 times, and this is heated and hardened to form a resin on the surface of the steel wire.

In the following No. 3 to 5 of the first table, the varnish "W143" for the polyurethane line specified in JIS C2351 (the varnish for enameled wire, "TPU F1 (product name)" ), the composition of the coating film after firing was a polyurethane, and the heating temperature was set to 250 °C.

In the first table below, the diameter of the resin-coated wire saw is shown.

Then, the single crystal file (60 mm × 20 mm × 50 mm) (sliced) was cut by a multi-wire saw ("D-500" manufactured by Ernst & Young Co., Ltd.) using the wire saw of No. 1 to No. 5 described above. The slicing process is carried out by spraying a slurry obtained by suspending SiC abrasive grains or diamond abrasive grains having an average particle diameter shown in the following Table 1 in a working fluid.

In No. 1 of the first table, the granules (Shinano Random (trade name)) manufactured by Shinano Electric Co., Ltd., which has an average particle diameter of 13 μm, are suspended in a working fluid (Yushiro Chemical). A slurry of "ethylene glycol aqueous solution" manufactured by Industry Co., Ltd.).

In No. 3 to 5 of the first table, the abrasive grains were suspended in a working fluid using a diamond abrasive grain (SMC Fine Dia (product name) manufactured by Sumiseki Materials Co., Ltd.) having an average particle diameter of 5.6 μm. A slurry of "ethylene glycol aqueous solution" manufactured by Yushiro Chemical Industry Co., Ltd.).

The concentration of SiC abrasive grains in the slurry is set to 50% by mass, the concentration of diamond abrasive grains is set to 5% by mass, and the temperature of the slurry is set to 20 to 25 ° C. The amount is set to 100 L/min.

The rate of increase (cutting speed) of the processing table on which the workpiece was placed was set to 0.3 mm/min, the line speed of the resin-coated wire saw was set to 500 m/min, and the tension of the resin-coated wire saw was set to 25 N, and the roll of the resin-coated wire saw was The number was set to 41 rolls, and the roll pitch of the resin-coated wire saw was set to 1 mm.

In No. 2 of the first table, the ethylene glycol-based aqueous solution containing no abrasive grains is sprayed between the wire saw and the single crystal crucible as a working liquid, and is subjected to slicing. The amount of cut at the time of slicing under the above conditions was measured, and the results are shown in Table 1 below.

Further, the difference (width loss) between the amount of cut and the wire diameter (diameter) of the wire saw was calculated, and the results are shown in Table 1 below.

The following table can be considered as follows. No. 1 is a comparative example in which a steel wire is used as a wire saw. When the workpiece is cut, the free abrasive grains are introduced between the cut surface and the resin-coated wire saw to excessively cut the workpiece, and as a result, the amount of cut of the workpiece is 160 μm. In addition, the width loss becomes a large 40 μm. This deteriorates productivity. In order to reduce the amount of cut, it is possible to reduce the diameter of the steel wire, but the steel wire itself is also cut when the workpiece is cut. If the diameter of the steel wire is too small, the steel wire is prone to breakage. When the diameter of the steel wire of No. 1 is 120 μm , in order to prevent the wire from being broken, the steel wire must be replaced so that the diameter of the steel wire is reduced to 100 μm .

No. 2 is a comparative example in which a wire saw with fixed abrasive grains is used as a wire saw, and since the workpiece is cut without spraying free abrasive grains, the amount of cut of the workpiece and the wire diameter of the wire saw with the fixed abrasive grains are attached. (diameter) is the same 155 μm.

No.3~5 is a resin coated wire using a resin coated on the surface of a steel wire. An example of cutting a workpiece by sawing, the cutting loss of the workpiece is 125 to 147 μm, and the width loss is a small 3 to 4 μm, which is known to improve productivity. Further, the surface of the resin-coated wire saw used in the slicing process was visually observed, and it was found that the abrasive grains were hardly adhered.

No.1~3, which uses a steel wire that draws a piano wire into a diameter of 120 μm as a plain wire, so it can be considered that it has the same tensile strength and the risk of disconnection. When No. 1 to 3 were compared, No. 3 (resin coated wire saw) had the smallest amount of cut and the most productivity.

According to the results obtained in the above Experimental Example 1, it is considered that the current mainstream thickness of 0.18 mm is cut out from a single crystal of 300 mm in length, and when the steel wire of the above No. 1 is used as the wire saw, the cut is caused. The amount is 160 μm, so the number of wafers taken is 882. When the wire saw with the fixed abrasive grains of the above No. 2 was used, the amount of cut was 155 μm, so the number of wafers taken was 895. When the wire saw of the resin No. 3 described above was used, the amount of cut was 135 μm, so the number of wafers taken was 952.

When the wire saw is coated with a resin, since the resin has an effect of improving the wear resistance of the steel wire, even if the slicing is performed, the steel wire itself is less likely to be reduced in diameter. Therefore, the diameter of the steel wire itself can be reduced. For example, when the resin-coated wire saw is coated with a resin-coated wire saw having a thickness of 6 μm on a surface of a steel wire having a diameter of 110 μm as in No. 5, since the amount of cut is 125 μm, the wafer is used. The number of acquisitions is 983, which can improve productivity.

On the other hand, when using a wire saw with fixed abrasive grains, the average particle diameter of the abrasive grains must be 15 μm or more from the viewpoint of ensuring the cutting property. The pull-out load applied by the wire saw with the fixed abrasive grain when it is pulled out from the workpiece must be set to 3 to 5 times that of the free abrasive grain. Therefore, the wire diameter of the wire saw with the fixed abrasive grains is set to 120 μm or less, which is difficult to achieve from the viewpoint of preventing wire breakage. Therefore, as shown in No. 2, it is difficult to set the amount of cut to 155 μm or less.

[Experimental Example 2]

The workpiece (single crystal crucible) is mounted on the processing table, and the wire saw is placed above the workpiece, and the abrasive grain is sprayed on the wire saw to raise the processing table, and the workpiece is cut by the wire saw in progress. The amount of cut of the single crystal crucible, the depth of the work-affected layer formed on the cut surface, and the surface roughness were measured.

The wire saw is a wire saw of the type shown in the second table below.

Nos. 21 to 32 in the following Table 2 are examples in which a resin-coated wire saw in which a resin is coated on the surface of a steel wire with a thickness shown in the following Table 2 is used as a wire saw.

In the above-mentioned steel wire, in the following Nos. 21 to 32 of the second table, the piano wire used in No. 1 of the above Experimental Example 1 was drawn into a steel wire having a diameter of 130 μm.

The above resin is formed by applying the following varnish to the surface of the steel wire and then curing it by heating. Specifically, before forming the resin, After the steel wire is degreased, the number of times of application is divided into 4 to 10 times to apply the following varnish, and the temperature of the resin is heated to 150 to 300 ° C, and this is heated to harden it in the steel wire. A resin is formed on the surface. The heating temperature is shown in Table 2 below.

In the No. 21 shown in the second table below, the varnish for polyester thread "W141" (manufactured by Tote Paint Co., Ltd., varnish for enameled wire "LITON 2100S (product name)", and burned by JIS C2351, was used. The composition of the formed coating film is a terephthalic acid-based polyester).

For the No. 22 to 28 and 30 to 32 shown in the second table below, the polyurethane varnish "W143" (made by Tote Paint Co., Ltd., varnish for enameled wire) specified in JIS C2351 is used. TPU F1 (trade name)", and the coating film composition after firing is a polyurethane).

In the No. 29 shown in the second table below, a varnish for polyamidoximine wire (Neoheat AI-00C (product name)), a varnish for enameled wire, manufactured by Tote Paint Co., Ltd., and after baking, were used. The composition of the coating film is polyamidamine.

In No. 33 of the following Table 2, the piano wire used in No. 1 of the above Experimental Example 1 was drawn into a steel wire having a diameter of 120 μm.

In Nos. 34 and 35 of the following Table 2, the piano wire used in No. 1 of the above Experimental Example 1 was drawn into a steel wire having a diameter of 160 μm.

In Nos. 36 and 37 of the following Table 2, a wire saw (diameter: 155 μm) with fixed abrasive grains used in No. 2 of the above Experimental Example 1 was used.

Here, the hardness of the resin was measured by a nanoindentation analysis method for the resin-coated wire saw shown in No. 25 to 32 of the following Table 2. Hardness is in Measured at room temperature (23 ° C) or 120 ° C. The specific measurement conditions are as follows.

"Common conditions for measurement at room temperature and 120 ° C"

Measuring device: "Nano Indenter XP/DCM" manufactured by Agilent Technologies

Analysis software: "Test Works 4" by Agilent Technologies

Tip: XP

Strain rate: 0.05 / sec

Measuring point interval: 30μm

Standard sample: molten vermiculite

"Measurement conditions at room temperature"

Measurement mode: CSM (continuous rigidity measurement method)

Excitation vibration frequency: 45Hz

Excitation vibration amplitude: 2nm

Pressing depth: up to 500nm

Measuring point: 15 points

Measurement environment: in air conditioning unit, room temperature 23 ° C

The hardness measurement at room temperature was carried out by a continuous rigidity measurement method, and the hardness in the range of 400 to 450 nm from the outermost surface of the resin film was measured. The hardness measurement was performed at 15 points, and the measurement results were averaged to calculate the hardness. In the measurement results, the abnormal value (the value is 3 times or more or 1/3 or less with respect to the average value) is removed, and a new measurement result is added to adjust the total value of the measurement points to 15 points.

"Measurement conditions at 120 ° C"

Measurement mode: Basic (load removal measurement method)

Pressing depth: up to 450nm

Measuring point: 10 points

Measuring environment: keep the sample tray at 120 °C with an electric resistance heater

The hardness measurement at 120 ° C was carried out by a load removal measurement method, and the hardness at a position where the indentation depth from the outermost surface of the resin film was 450 nm was measured. In other words, when the hardness is measured while heating the sample, the continuous rigidity measurement method in which the hardness is measured at room temperature cannot be used. Therefore, the load is adjusted so that the measurement position becomes a position at which the depth of penetration of the outermost surface is 450 nm. Hardness measurement was performed.

The hardness measurement at 120 ° C was carried out by attaching the resin-coated wire saw to a sample tray for a metal indentation method using a ceramic-based adhesive, and heating the sample tray with a resistance heater while maintaining the temperature at 120 ° C. .

The hardness measurement at 120 ° C was carried out at 10 o'clock, and the measurement results were averaged to calculate the hardness. In the measurement results, the abnormal value (the value is 3 times or more or 1/3 or less with respect to the average value) is removed, and a new measurement result is added to adjust the total value of the measurement points to 10 points.

The hardness measured at room temperature or 120 ° C is shown in Table 2 below.

Then, using a wire saw, a single-line wire (60 mm × 20 mm × 50 mm) (sliced) was cut with a multi-wire saw ("D-500" manufactured by Ernst & Young Co., Ltd.) to produce a cut body. The slicing process is carried out by spraying the following slurry between a wire saw and a single crystal crucible, and the slurry is suspended in ethylene glycol of an average particle diameter of the diamond abrasive grains or SiC abrasive grains shown in the following Table 2. system Made from an aqueous solution.

In No. 21, 24 to 32, 34, and 35 of the following Table 2, diamond abrasive grains having an average particle diameter of 5.6 μm (SMC Fine Dia (product name), manufactured by Sumiseki Materials Co., Ltd.) were used for the abrasive grains. A slurry suspended in a working fluid ("ethylene glycol aqueous solution" manufactured by Yushiro Chemical Industry Co., Ltd.).

In No. 22 and No. 23 of the following Table 2, SiC abrasive grains ("Shinano Random (product name)", manufactured by Shinano Electric Co., Ltd.) having an average particle diameter of 5.6 μm were suspended in the working fluid. A slurry of ""ethylene glycol aqueous solution" manufactured by Yushiro Chemical Industry Co., Ltd.).

In No. 33 of the following Table 2, SiC abrasive grains ("Shinano Random (trade name)" manufactured by Shinano Electric Co., Ltd.) having an average particle diameter of 13 μm were suspended in a working fluid (Yushiro Chemical). A slurry of "ethylene glycol aqueous solution" manufactured by Industry Co., Ltd.).

The diamond abrasive grain concentration was set to 5% by mass, the SiC abrasive grain concentration, No. 22 and 23 were set to 5% by mass, No. 33 was set to 50% by mass, and the slurry temperature was set to 20 to 25 ° C, and the amount of slurry was supplied. Set to 100L/min. The rising speed of the processing table on which the workpiece is placed is 0.1 mm/min, 0.3 mm/min or 1 mm/min, the wire speed of the resin-coated wire saw is 500 m/min, and the tension of the resin-coated wire saw is 25 N, resin coating The number of rolls of the wire saw was set to 41 rolls, and the roll pitch of the resin-coated wire saw was set to 1 mm.

In No. 36 and 37 of the second table below, B which does not contain abrasive grains The diol aqueous solution is sprayed between the wire saw and the single crystal crucible as a working liquid, and is sliced.

Next, the surface of the resin-coated wire saw used in the slicing process was visually observed. As a result, it was observed that the surface of the resin-coated wire saw used in No. 21 to 31 hardly bite into the abrasive grains. On the other hand, the surface of the resin-coated wire saw used in No. 32 was observed to bite into the abrasive grains. Fig. 4 is a photograph instead of a photograph of the surface of the resin-coated wire saw used in the photograph No. 32.

Here, in the resin-coated wire saw used in Nos. 25 to 32, the number of abrasive grains bitten on the surface of the resin was measured by the following procedure. That is, the surface of the used resin-coated wire saw was photographed by an optical microscope at 400 times, and the observed abrasive grains in the region of 50 μm × 200 μm near the center of the resin-coated wire saw were visually observed. number. The measurement area is shown by a broken line in the above fourth figure.

Next, the cut body obtained by the slicing process was measured for the depth of the work-affected layer formed on the cut surface and the surface roughness of the cut surface.

"Processing Deterioration Layer Depth"

The depth of the work-affected layer formed on the cut surface is as shown in Fig. 5(a), and the cut body is embedded in the resin so as to be inclined at 4° with respect to the horizontal direction, and as shown in Fig. 5(b) ) The cut body and the resin are polished so that the cut surface of the cut body is exposed. Then, the exposed surface was etched by an etching liquid having the composition shown in Table 3 below, and the affected layer formed during the cutting of the workpiece was observed by an optical microscope (the etch pit introduced during the cutting of the workpiece) .

Figure 6 to Figure 11 show the cutting of the workpiece with an optical microscope. Photo of the section. Fig. 6 is No. 25, Fig. 7 is No. 27, Fig. 8 is No. 32, Fig. 9 is No. 33, Fig. 10 is No. 35, and Fig. 11 is No. 37. Alternative photo.

When observed by an optical microscope, the work-affected layer was displayed in black, and the depth (thickness) thereof was measured, and the measurement results are shown in Table 2 below.

"Surface roughness"

The surface roughness of the cut surface was measured by using "CS-3200 (device name)" manufactured by Mitsutoyo Co., Ltd. in the cutting direction (depth direction of cutting) to cover the arithmetic mean roughness Ra of 10 mm.

The measurement results are shown in Table 2 below.

The following table can be considered as follows. No. 21 to 31 are examples in which a cut body is produced by using a resin-coated wire saw obtained by the procedure defined in the present invention, and the depth of the work-affected layer formed on the cut surface is 5 μm which is shallow, and the arithmetic of the cut surface is performed. The average roughness Ra is 0.5 μm or less and is substantially smooth.

On the other hand, Nos. 32 to 37 are examples in which a cut piece is produced using a wire saw which has not been subjected to the steps specified in the present invention. Among these, although No. 32 is an example in which a workpiece is cut by a resin-coated wire saw having a resin coated on the surface of a steel wire, the resin is too soft, causing the abrasive grains to bite into the resin during the slicing process. Further, the depth of the work-affected layer formed on the cut surface is more than 5 μm.

In No. 33 to 35, since a steel wire is used as the wire saw, the abrasive grains are caught between the steel wire and the workpiece to increase the amount of cut. In addition, the processed metamorphic layer formed on the cut surface has a deeper depth and a rougher surface roughness.

In No. 36 and 37, since a wire saw with fixed abrasive grains was used as the wire saw, the amount of cut was large, and the depth of the work-affected layer formed on the cut surface was deep and the surface roughness was coarse.

In the above Nos. 21 to 31, since the arithmetic mean roughness Ra of the cut surface is 0.5 μm or less, when the cut body is used as a material of, for example, a solar cell, the fine structure can be directly etched on the surface in this state. . On the other hand, in the above Nos. 33 to 37, since the arithmetic mean roughness Ra of the cut surface exceeds 0.5 μm, it is necessary to perform etching for smoothing the cut surface before etching the fine structure.

Next, the results of measuring the hardness of the resin and the number of the abrasive grains bitten on the surface of the resin No. 25 to 32 were compared, and the following can be considered. In No. 25 to 32, the hardness of the resin measured at room temperature was about 0.27 GPa, which was about the same result. However, the hardness of the resin measured at 120 ° C was 0.04 to 0.28 GPa. Great change. The reason for this change is that the difference in the type of resin or the heating temperature can be considered.

Here, Fig. 12 shows the relationship between the hardness of the resin measured at 120 ° C and the number of abrasive grains bitten on the surface of the resin (the number of observation fields of 50 μm × 200 μm). From Fig. 12, it can be observed that the greater the hardness of the resin measured at 120 ° C, the less the number of abrasive grains biting into the surface of the resin tends to decrease.

Further, Fig. 13 shows the relationship between the hardness of the resin measured at 120 ° C and the depth of the worked-affected layer formed on the cut surface. From Fig. 13, it can be observed that the greater the hardness of the resin measured at 120 ° C, the smaller the depth of the affected layer is. In addition, it can be observed that if When the hardness of the resin measured at 120 ° C is 0.07 GPa or more, the depth of the affected layer can be suppressed to 5 μm or less.

From the above-mentioned Fig. 12 and Fig. 13, it can be observed that the depth of the processed metamorphic layer tends to decrease as the number of abrasive grains bitten on the surface of the resin decreases.

The present invention has been described in detail above with reference to the specific embodiments thereof, and it is obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. .

This application is based on the Japanese franchise (Japan Special Purpose 2010-038017) filed on February 23, 2010, and the Japanese franchise (Japan Special Purpose 2010-161093) filed on July 15, 2010. This content is cited as a reference.

Industrial availability:

According to the present invention, the surface of the wire saw is covered with a resin and the hardness is adjusted. Therefore, it is possible to suppress the introduction of the abrasive grains between the cut surface and the resin-coated wire saw by the resin while introducing the abrasive grains and cutting them. This can suppress the formation of the work-affected layer on the surface of the cut body. Further, when the resin is covered with a wire saw to cut the workpiece, a cut body having a smooth surface can be produced. Therefore, in the step of the downstream side, the step of removing the affected layer or the etching step for smoothing the surface can be omitted, and the productivity of the cut body can be improved.

Furthermore, when the wire saw of the resin of the present invention is used, the abrasive grain can be suppressed Since the cut surface is introduced between the cut surface and the resin-coated wire saw, the amount of cut can be reduced to improve the productivity of the cut body.

Claims (6)

A method of designing a resin-coated wire saw is a method of designing a resin-coated wire saw including a step of coating a steel wire with a resin having a predetermined hardness to obtain a resin-coated wire saw, characterized in that the following is repeated by (1) )~(4), to adjust the hardness of the resin so that the depth of the work-affected layer on the cut surface of the workpiece is acceptable; (1) cutting the workpiece with the obtained resin-coated wire saw, and (2) investigating the cut of the workpiece The depth of the work-affected layer on the section, (3) confirming whether the depth of the affected layer is acceptable, and (4) when the film is unqualified, the steel wire is coated with a harder resin. The method for designing a resin-coated wire saw according to claim 1, wherein the steel layer is coated with a harder resin when the depth of the modified layer is deeper than 5 μm. A method of designing a resin-coated wire saw is a method of designing a resin-coated wire saw including a step of coating a steel wire with a resin having a predetermined hardness to obtain a resin-coated wire saw, characterized in that the following is repeated by (1) ) (4), to adjust the hardness of the resin so that the surface roughness of the cut surface of the workpiece is acceptable; (1) cutting the workpiece with the obtained resin-coated wire saw, and (2) investigating the cutting of the workpiece The surface roughness on the surface, (3) confirm that the surface roughness is acceptable, and (4) when the film is unqualified, the steel wire is coated with a harder resin. The method for designing a resin-coated wire saw according to claim 3, wherein the surface roughness is harder than 0.5 μm, and is harder. The resin is used to coat the steel wire. The method for designing a resin-coated wire saw according to the first or third aspect of the invention, wherein the resin has a film thickness of 2 to 15 μm. The method for designing a resin-coated wire saw according to the first or third aspect of the invention, wherein the steel wire has a wire diameter of 130 μm or less.