TWI521057B - Water-soluble working fluid for fixed abrasive grain wire saw - Google Patents

Description

Water-soluble working fluid for fixed abrasive fine wire cutter

The present invention relates to a water-soluble working fluid for a fixed abrasive fine wire cutter.

In recent years, in order to reduce the manufacturing cost of semiconductor components, the large-diameter of germanium wafers is rapidly developing, and the improvement of the wafer-cutting processing technology becomes important. As the cutting processing technique, for example, there is a cutting method using a thin wire tool (fine wire cutter) which has less cutting loss and is excellent in processing efficiency. In the cutting method using the thin wire cutter, there are a free abrasive grain method and a fixed abrasive grain method. The free abrasive grain method has the following problems: (1) A slurry obtained by dispersing abrasive grains in an oil agent is used as a processing. Liquid, so the cutting process or the surrounding environment is seriously polluted; (2) the slurry containing a large amount of cutting debris generated during cutting must be discarded; (3) the free abrasive grains are difficult to separate from the cutting debris; (4) for fine line movement There are limits to speed and limits in terms of processing efficiency. In order to solve the above problems, a fixed abrasive grain type fine wire cutter which is obtained by fixing abrasive grains to a surface of a fine wire such as a piano wire by electrodeposition or a resin binder is used. For example, Patent Document 1 proposes a fixed abrasive fine wire cutter for fixing abrasive grains of 30 to 60 μm with a resin binder. The high-efficiency cutting process can be performed by moving the fixed abrasive fine wire cutter at a line speed of 1000 to 2500 m/min and cutting the brittle material.

On the other hand, the use of a fixed abrasive fine wire cutter for brittle materials At the time of cutting processing, the working fluid is used simultaneously for the purpose of lubrication, cooling, dispersion of cutting chips, and the like. As the working fluid, it is preferred to use a water-soluble one. The non-aqueous non-aqueous processing liquid has the following problems: the non-aqueous volatile component (solvent component) deteriorates the working environment, the processing fluid becomes a flammable liquid, and the washing step or waste liquid treatment after processing is equal to the use of the water-soluble working fluid. The situation becomes more complicated.

Further, in the case where the workpiece is defective, the following problems occur. That is, hydrazine has a high reactivity, and reacts with water or a base in the working fluid during the cutting process to generate hydrogen gas, which is flammable. Therefore, it is preferred to reduce the reactivity of the working fluid with ruthenium. From the above viewpoint, a working fluid as shown in Patent Document 2 has been proposed.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2001-054850 [Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-082334

As a working fluid used for cutting a fine wire obtained by fixing and granulating a brittle material such as enamel, sapphire, glass, ceramic fiber or enamel, a diol is widely used as the processing liquid disclosed in Patent Document 2. Class and water are the main components. However, the conventional working fluid as described above sometimes does not sufficiently perform a stable cutting process. In particular, it is known that the cutting debris is mixed in Various problems occur in the processing fluid. When the machining liquid is used for cutting a workpiece such as a crucible, the cutting debris of the workpiece is mixed into the machining liquid. At this time, depending on the situation, the viscosity of the working fluid may become high to the extent that the processing performance is affected. Further, there is a case in which the cutting debris is mixed into the working fluid, which causes a problem that the cutting debris blocks the piping of the apparatus, and a firm fixing is formed in the groove of the hanging roller of the main roller (hereinafter, Sometimes referred to as "hard cake", which results in a stitching of the thin line (the thin line is offset from the groove).

Accordingly, an object of the present invention is to provide a water-soluble working fluid for a fixed abrasive fine wire cutter which can suppress an increase in viscosity when cutting chips are mixed, and a pipe jam or hard knot of a device caused by mixed cutting chips. The generation of blocks.

In order to solve the above problems, the inventors of the present invention conducted diligent research and found the following matters.

(1) When the cutting debris of the workpiece is mixed into the working fluid, the cutting debris is fine powder (about 1 μm), or the cutting debris of the active new surface interacts with each other to contain the surrounding working fluid and agglomerate, and the cutting is broken. The swarf functions as a tackifier, whereby the viscosity of the processing fluid rises remarkably.

(2) If the cutting debris of the workpiece is mixed into the machining fluid, the specific gravity of the cutting debris is greater than the specific gravity of the composition constituting the machining fluid, so that the cutting debris having a large specific gravity precipitates. At this time, if the cutting chips are uniformly precipitated in a dispersed state, then The precipitated cutting chips are firmly and tightly solidified, and the piping of the equipment is clogged or hard agglomerates.

(3) The problem of the above (1) and (2) can be solved by appropriately adjusting the conductivity of the working fluid to control the dispersion behavior of the cutting debris mixed into the working fluid.

The present invention has the following constitution based on the above findings. which is:

A first aspect of the present invention is a water-soluble working fluid for a fixed abrasive fine wire cutter comprising (C) a carboxylic acid, (D) a compound which is dissolved in water to exhibit basicity, (E) water, and at 25 ° C. The lower conductivity is 300 μS/cm or more and 3000 μS/cm or less, the pH at 25° C. is 5 or more and 10 or less, and the quasi-use liquid formed by adding 10% by mass of niobium powder having an average particle diameter of 1.5 μm and stirring is added. The viscosity is less than 30 mPa at 25 °C. s.

In the present invention, the term "viscosity" means the viscosity measured by a Brookfield viscometer. In addition, the "average particle diameter" means a measurement using a laser diffraction/scattering type particle size distribution measuring apparatus "LA910" manufactured by Horiba, Ltd.

The processing liquid according to the first aspect of the present invention preferably further comprises at least one selected from the group consisting of (A) a copolymer comprising an alcohol, ethylene oxide and propylene oxide, and a polyoxyalkylene glycol. Nonionic surfactant.

Moreover, it is preferable that the working liquid of the first aspect of the present invention further contains (B) a glycol.

A second aspect of the present invention is a water-soluble working fluid for a fixed abrasive fine wire cutter comprising: (A) copolymerization from an alcohol, ethylene oxide and propylene oxide At least one or more nonionic surfactants selected from the group consisting of polyoxyalkylene glycols are contained in an amount of 0.1% by mass or more and 8% by mass or less; and (B) 0.1% by mass or more and 80% by mass or less of the diols. (C) carboxylic acid 0.01% by mass or more and 5% by mass or less; (D) dissolved in water to exhibit 0.01% by mass or more and 7% by mass or less of the basic compound; and (E) water; and conductive at 25 ° C The rate is 300 μS/cm or more and 3000 μS/cm or less, the pH at 25 ° C is 5 or more and 10 or less, and the viscosity of the quasi-use liquid formed by adding 10% by mass of the niobium powder having an average particle diameter of 1.5 μm and stirring is Less than 30 mPa at 25 °C. s.

The working fluid according to the first and second aspects of the present invention preferably has a surface tension of 20 mN/m or more and 50 mN/m or less at 25 °C.

Moreover, it is preferable that the working liquid of the first and second aspects of the present invention further contains a water-soluble polymer and/or an antifoaming agent.

In addition, it is preferable that the processing liquid of the first and second aspects of the present invention has a total mass of 100% by mass and contains (E) water of 1.0% by mass or more and 99.7% by mass or less.

According to the present invention, it is possible to provide a water-soluble working fluid for a fixed abrasive fine wire cutter capable of suppressing an increase in viscosity when a cutting debris is mixed, and a pipe blockage or hard agglomeration of a device caused by the mixed cutting debris. .

<Properties of the processing liquid of the present invention>

(Conductivity)

The water-soluble working fluid for a fixed abrasive fine wire cutter of the present invention has a conductivity of 300 μS/cm or more and 3000 μS/cm or less at 25 °C. The upper limit of the conductivity is preferably 2000 μS/cm or less, more preferably 1000 μS/cm or less.

The conductivity is an index indicating the ease of conduction of electricity and is defined as the reciprocal of the resistance. The higher the concentration of the ionic substance contained in the working fluid, the higher the conductivity of the working fluid, and the easier it is to conduct electricity. Further, the higher the concentration of the ionic substance contained in the working fluid, the more easily the fine particles (cutting chips) having electric charge are aggregated in the working liquid. That is, the higher the conductivity of the working fluid, the larger the apparent particle size of the cutting debris mixed into the working fluid, and the easier the cutting debris is to precipitate. Further, it is considered that since the cutting chips are precipitated in a three-dimensional and expanded state at this time, it is difficult to cause hard agglomeration. Further, by agglomerating and precipitating the cutting chips, the sedimentation speed of the cutting chips can be increased, and the cutting chips can be easily separated from the machining liquid by centrifugal separation or the like.

However, when the conductivity is too high, the cutting debris is difficult to disperse in the working fluid, so the viscosity of the working fluid is likely to rise.

On the other hand, in the case where the conductivity is low (pure water or the like is a representative example), the charged microparticles (cutting debris) are dispersed by the repulsive force of each electric charge, and even if the cutting debris is mixed, the viscosity of the working fluid is also Hard to rise.

However, if the conductivity of the working fluid is too low to cause the cutting chips to be excessively dispersed in the working fluid, the cutting chips are uniformly precipitated in a dispersed state and firmly and tightly cured. It is easy to produce the following bad conditions: due to the cutting as described above The chips are precipitated and firmly and tightly cured to cause the piping of the apparatus to be clogged; or the jumper of the fine line (the thin line deviates from the groove) or the like due to the formation of hard agglomerates in the fine line grooves of the main guide rolls. Further, if the cutting chips are excessively dispersed in the working fluid, the rate of precipitation of the cutting chips becomes slow. Therefore, when the cutting debris in the working fluid is removed for the purpose of recycling the waste liquid or the processing liquid, it is difficult to remove the cutting debris in the working fluid by centrifugal separation or the like.

According to the working fluid of the present invention, by setting the electrical conductivity at 25 ° C to the above range, the cutting chips can be appropriately dispersed, aggregated, and precipitated in the working fluid. As a result, it is possible to suppress an increase in the viscosity of the working fluid or to suppress clogging of the piping or hard agglomeration of the equipment.

The conductivity of the working fluid of the present invention can be adjusted according to the amount of the substance dissolved in water and ionized in the working fluid. For example, the conductivity of the working fluid can be appropriately adjusted by adjusting the amount of the component (C) (carboxylic acid) or (D) (the compound which is dissolved in water to exhibit alkalinity) in the working fluid. Further, the working fluid of the present invention can also be used by dilution with water. In this case, the conductivity of the diluted working fluid is also preferably in the above range.

(viscosity)

The viscosity of the processing liquid of the present invention is preferably 1 mPa at 25 ° C. Above s and 25 mPa. Below S, the upper limit is preferably 20 mPa. s below. When the viscosity of the working fluid is too high, the amount of water in the working fluid is usually small, and the ability to absorb heat generated by processing using a fixed abrasive fine line (hereinafter, referred to as "cooling property") is relatively small. weak. Therefore, there is a reduction in machining accuracy or Problems such as increased load on tools. Further, the viscosity of the liquid (quasi-use liquid) obtained by dispersing the predetermined niobium powder in the processing liquid of the present invention is preferably 1 mPa at 25 ° C. Above s and less than 30 mPa. s, more preferably 1 mPa. Above s and 20 mPa. s is below, and further preferably 1 mPa. Above s and 15 mPa. s below. The viscosity of the quasi-use liquid is 10% by mass of cerium powder (average particle diameter of 1.5 μm) added to the working fluid of the present invention, and after mixing and mixing, a stainless steel ball (2 mm in diameter) is placed, and the mixture is stirred at 1000 rpm. The stainless steel ball was filtered out and measured for the obtained quasi-use liquid. If the viscosity of the above-mentioned working fluid itself is high, the viscosity of the quasi-use liquid containing niobium powder is inevitably high. Furthermore, the viscosity of the working fluid and the quasi-use fluid can be measured by a Brookfield viscometer.

The viscosity of the working fluid of the present invention can be, for example, the following components (A) (nonionic surfactant), (B) component (diol), (C) component (carboxylic acid), and (D) component (dissolved). The amount of the compound (E) which is alkaline in water and the component (E) (water) is appropriately adjusted. Further, it can be adjusted according to the blending of other additives (for example, a viscosity adjuster). Further, the working fluid of the present invention can also be used by dilution with water. In this case, the viscosity of the diluted working fluid is also preferably in the above range.

(pH)

The pH of the working fluid of the present invention is 5 or more and 10 or less at 25 °C. When the pH of the working fluid is less than 5, the corrosiveness of the working fluid to the metal is improved, and the equipment in contact with the corrosive working fluid or the metal member attached to the thin wire cutter is defective. Corrosion to metals depends on the amount of water contained in the processing fluid However, it is easy to suppress the above corrosion by setting the pH of the working liquid to 5 or more at 25 °C. From the above viewpoints, the pH of the working fluid of the present invention is more preferably 6 or more at 25 ° C, and still more preferably 7 or more. On the contrary, when the pH of the working fluid exceeds 10, the reactivity of the working fluid with the cutting debris (矽) mixed into the working fluid is improved, and the processing liquid and the cutting debris react to generate hydrogen gas, or processing during processing. The viscosity of the liquid rises markedly. By setting the pH of the working liquid to 10 or less at 25 ° C, it is easy to suppress the generation of hydrogen during processing or the increase in viscosity of the working liquid during processing.

The pH of the working fluid of the present invention can be, for example, the content of the following component (B) (diol), or (C) component (carboxylic acid) and (D) component (a compound which is dissolved in water to exhibit basicity). Appropriate adjustments. Further, it may be adjusted according to other additives (for example, a pH adjuster). Further, the working fluid of the present invention can also be used by dilution with water. In this case, the pH of the diluted working fluid is also preferably in the above range.

(Surface Tension)

The present inventors have found that the conventional working fluid has insufficient wettability to the fine thread used or the gap to the workpiece, and should reach the processing portion (the portion in the workpiece that is in contact with the fine line). Insufficient processing fluid sometimes leads to a decrease in processability. When the surface tension of the working fluid is too high, the wettability or permeability of the working fluid is deteriorated, and the working fluid cannot reach the processing portion. In an extreme case, the processing section performs a cutting process in a dry state. Therefore, the heat generated in the processed portion becomes conspicuous and an excessive load is applied to the tool to break the thin wire, or the machining accuracy is lowered to deteriorate the surface roughness of the workpiece. After that. From the above viewpoints, the surface tension of the working fluid of the present invention is preferably 50 mN/m or less, more preferably 45 mN/m or less, and still more preferably 40 mN/m or less at 25 °C. By setting the surface tension of the working fluid to the above range, the wettability to the workpiece (such as ruthenium) or the fine thread (nickel or resin) or the permeability to the processed portion can be improved.

On the other hand, when the surface tension is low, the foaming of the working fluid becomes strong. Therefore, there is a problem in that the bubble is bitten into the machining liquid at the time of cutting processing, and the cooling property is weakened. Further, since air bubbles are generated from the machining liquid, there is a problem that the air bubbles overflow from the grooves provided for storing the machining liquid. From the above viewpoints, the surface tension of the working fluid of the present invention is preferably 20 mN/m or more, more preferably 30 mN/m or more at 25 °C.

The surface tension of the working fluid of the present invention can be appropriately adjusted, for example, by adjusting the amount of the following component (A) or the amount of the antifoaming agent. Further, the working fluid of the present invention can also be used by dilution with water. In this case, the surface tension of the diluted working fluid is also preferably in the above range.

<Components Contained in the Processing Fluid of the Present Invention>

The processing liquid of the present invention may contain, for example, the components described below.

((A) component)

In the working fluid of the present invention, as the component (A), at least one selected from the group consisting of a copolymer of alcohol, ethylene oxide and propylene oxide, and a polyoxyalkylene alkyl glycol may be contained. Surfactant. By containing the component (A) in the working fluid, the surface tension of the working fluid can be lowered to enhance the wetting of the working fluid. Sex or permeability.

The alcohol to be used as the above alcohol is not particularly limited, and for example, an alcohol having 8 or more and 12 or less carbon atoms can be used.

Specific examples of the polyoxyalkylene glycols include polyethylene glycol, polypropylene glycol, a copolymer of polyoxyethylene and polyoxypropylene, and the like. The mass average molecular weight (in terms of standard polystyrene using gel permeation) of the polyoxyalkylene glycol used in the present invention is preferably 10,000 or less, more preferably 5,000 or less, still more preferably 3,500 or less.

The working fluid of the present invention can be produced by appropriately diluting with water according to the working environment of the cutting process. In other words, a concentrated composition containing components other than water in the components contained in the working fluid of the present invention can be produced, and the concentrated composition can be diluted with water at a work site or the like to prepare a working fluid of the present invention. Further, it is also possible to produce a high-concentration working fluid of the present invention (the processing liquid of the present invention is prepared with a small amount of water), and it can be used as it is according to the working environment of the cutting process, or can be further diluted with water. When the working fluid of the present invention is actually used for cutting, the lower limit of the content of the component (A) is preferably 0.1% by mass or more based on the mass of the entire working fluid of the present invention (100% by mass), more preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and the upper limit is preferably 0.8% by mass or less, more preferably 0.7% by mass or less, still more preferably 0.6% by mass or less. In the case where the high-concentration working fluid of the present invention is produced as described above, the upper limit of the content of the component (A) is preferably based on the mass of the entire working fluid of the present invention (100% by mass). 8 mass% or less, more preferably 7 mass% or less, and further preferably It is 6 mass% or less.

((B) component)

Further, the working fluid of the present invention may contain a glycol as the component (B). By containing the component (B) in a predetermined amount in the working fluid of the present invention, components other than the component (B) can be stably dissolved in the working fluid of the present invention, or drying of the working fluid of the present invention can be suppressed.

Specific examples of the diol used as the component (B) include ethylene glycol, propylene glycol, 1,4-butanediol, hexanediol, neopentyl glycol, diethylene glycol, and triethylene glycol. , dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, a copolymer of ethylene glycol and propylene glycol, and a copolymer of ethylene oxide and propylene oxide, triethylene glycol monobutyl ether, triethyl A glycol monoalkyl ether such as diol monomethyl ether, diethylene glycol monobutyl ether or tripropylene glycol monomethyl ether; or a water-soluble glycol such as a monoalkyl ether of a copolymer of ethylene oxide and propylene oxide. Among the above-exemplified diols, propylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol or polypropylene glycol is preferably used, and particularly preferably dipropylene glycol or diethylene glycol. These may be used alone or in combination of two or more. Further, a copolymer comprising two or more of the above components may also be used. The mass average molecular weight (in terms of standard polystyrene using gel permeation) of the above diols is preferably 100 or more and 700 or less, more preferably 100 or more and 200 or less.

When the working fluid of the present invention is actually used for the cutting process, the lower limit of the content of the component (B) is preferably 0.1% by mass or more based on the mass of the entire working fluid of the present invention (100% by mass), more preferably 0.5% by mass or more, and further preferably The content is 2% by mass or more, and the upper limit is preferably 8% by mass or less, and more preferably 7% by mass or less. Further, in the case where a high concentration of the working fluid of the present invention is produced as described above, the upper limit of the content of the component (B) is preferably based on the mass of the entire processing liquid of the present invention (100% by mass). It is 80% by mass or less, more preferably 70% by mass or less. By setting the content of the component (B) to the above range, components other than the component (B) can be stably dissolved in the working fluid of the present invention, or drying of the working fluid of the present invention can be suppressed.

((C) component)

Further, the working fluid of the present invention may contain a carboxylic acid as the component (C). By including the component (C) in a predetermined amount in the working fluid of the present invention, the combination of the following component (D) can be utilized to adjust the pH or conductivity of the working fluid of the present invention to cushion the cutting. The fluctuation of the pH of the working fluid of the present invention at the time of processing can alleviate the corrosion of the metal of the working fluid of the present invention, and can stably dissolve other components in the working fluid of the present invention.

Specific examples of the carboxylic acid used as the component (C) include citric acid, succinic acid, lactic acid, malic acid, adipic acid, oxalic acid, dodecanedioic acid, and acetic acid. Among them, citric acid and succinic acid are preferably used, and citric acid is more preferably used. These may be used alone or in combination of two or more.

When the working fluid of the present invention is actually used for the cutting process, the lower limit of the content of the component (C) is preferably 0.01% by mass or more based on the mass of the entire working fluid of the present invention (100% by mass), more preferably 0.1% by mass or more. The upper limit is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, still more preferably 0.2% by mass. Below mass%. Further, in the case where the high-concentration working fluid of the present invention is produced as described above, the upper limit of the content of the component (C) is preferably based on the mass of the entire processing liquid of the present invention (100% by mass). It is 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less. By setting the content of the component (C) to the above range, the effect of containing the component (C) can be exhibited. If the content of the component (C) is too small, the effect may not be sufficiently obtained. If the content of the component (C) is too large, the amount of the component (D) used for neutralizing the component (C) increases, which leads to an unexpected result. The external conductivity increases and the metal is easily corroded.

(D) a compound which is dissolved in water and exhibits basicity

Further, the working fluid of the present invention contains a compound which is dissolved in water and exhibits alkalinity (hereinafter, referred to as "basic compound") as the component (D). By including the component (D) in a predetermined amount in the working fluid of the present invention, the combination of the component (C) and the component (C) can be used to adjust the pH or conductivity of the working fluid of the present invention, which can be used during cutting. By buffering the fluctuation of the pH of the working fluid of the present invention, the corrosion of the metal of the working fluid of the present invention can be alleviated, and other components can be stably dissolved in the working fluid of the present invention.

Specific examples of the basic compound used as the component (D) include a compound containing an alkali metal element such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate or potassium hydrogencarbonate, or triethanolamine. An amine such as triisopropanolamine, ethylenediamine, N-(2-aminoethyl)-2-amineethanol or N-(β-aminoethyl)ethanolamine. These may be used alone or in combination of two or more.

When the working fluid of the present invention is actually used for cutting, the lower limit of the content of the component (D) is preferably 0.01% by mass or more based on the mass of the entire working fluid of the present invention (100% by mass), more preferably 0.1% by mass or more, and the upper limit is preferably 0.7% by mass or less, more preferably 0.6% by mass or less, still more preferably 0.5% by mass or less. Further, in the case where the high-concentration working fluid of the present invention is produced as described above, the upper limit of the content of the component (D) based on the mass of the entire working fluid of the present invention is preferably 7 mass% or less, more preferably 6% by mass or less, further preferably 5% by mass or less. By setting the content of the component (D) to the above range, the effect of containing the component (D) can be exhibited. Further, when the content of the component (D) is too large, the amount of the component (C) necessary for neutralization increases, which leads to an unexpected increase in the electrical conductivity of the present invention and deteriorates the dispersion of the cutting chips.

Further, the working fluid of the present invention may contain a salt formed of the component (C) and the component (D) in place of the component (C) and the component (D). The content of the salt is preferably such that it is converted to the above content in terms of the components (C) and (D). Specific examples of the salt include an alkali metal salt of a carboxylic acid or an amine salt of a carboxylic acid.

((E) component)

Further, the working fluid of the present invention contains water as the component (E). The water is distilled water, tap water, or the like, and the kind thereof is not particularly limited. However, in the case of using water having a high conductivity such as water of high hardness, it is preferred to use an amount of ions to be adjusted. For example, tap water has different ion concentrations (hardness) depending on regions and countries.

Compared with the conventional free abrasive method, the cutting process using the fixed abrasive granulated fine wire has a large amount of heat generated accompanying the cutting process. Therefore, the load on the thin wire or the workpiece is increased. Further, it can be seen that the workpiece is swollen with heat, which adversely affects the processing accuracy. Further, it is understood that the diamond abrasive grains fixed on the thin wires are easily worn and adversely affect the life of the tool. Therefore, cooling is required for the processing fluid in the process. In order to improve the cooling performance, it is necessary to increase the amount of water in the working fluid. However, when ruthenium is used as a workpiece, water in the working fluid may react with the cutting debris to generate hydrogen gas. Therefore, in the conventional aqueous working fluid, it is difficult to increase the amount of water, and thus the problem regarding the cooling property has not been fundamentally solved. When the cutting debris mixed in the working fluid reacts with the water in the working fluid to generate hydrogen gas, the following problems may occur: the flow rate of the machining fluid becomes unstable because the air bubbles are trapped when the machining fluid is supplied by the pump. Or the liquid specific gravity is lowered by the bite of the air bubbles, so that the abnormality is detected in the thin wire cutter that controls the working fluid by the liquid specific gravity, and the processing is stopped. Moreover, there is also a risk that the generated hydrogen gas will explode due to static electricity or the like.

According to the working fluid of the present invention, by blending the above components and setting the pH to the predetermined value, the reaction between the working fluid and the cutting debris can be suppressed, so that the moisture content can be increased and the cooling property can be improved. That is, according to the working fluid of the present invention, the suppression of hydrogen generation and the improvement of the cooling property can be simultaneously achieved.

Further, in the case where the amount of water in the working fluid is increased, there is a possibility that the equipment to be contacted by the working fluid or the metal member of the thin wire is corroded. However, according to the invention The processing liquid can suppress corrosion by increasing the value of the component (B) or the component (C) or the pH within the predetermined range as described above, thereby increasing the moisture content and improving the cooling property. That is, according to the working fluid of the present invention, the suppression of corrosion and the improvement of the cooling property can be simultaneously achieved.

The lower limit of the water content is preferably 10% by mass or more, more preferably 25% by mass or more, and still more preferably 50% by mass or more based on the mass of the entire working fluid of the present invention (100% by mass). By setting the water content to 10% by mass or more, it is easy to ensure the cooling property of the working fluid, and it is easy to prevent the reduction in the processing accuracy or the load on the tool. On the other hand, the upper limit is preferably 99.7% by mass or less. When the water content is 100% (pure water), it is not suitable as a working fluid from the viewpoint of wettability or permeability, and it is considered to be effective even if a small amount of other components specified in the present invention are contained. Further, the more water contained in the working fluid, the better the cooling property of the working fluid.

(water soluble polymer)

The working fluid of the present invention may contain a water-soluble polymer. By setting the conductivity to a predetermined value as described above, the working fluid of the present invention can control the dispersibility of the cutting debris in the working fluid. By including the water-soluble polymer in the working fluid of the present invention, it is easier to control the dispersibility of the cutting chips mixed into the working fluid.

As the water-soluble polymer which can be used in the present invention, a user skilled in the working fluid can be used without particular limitation. For example, polyvinylpyrrolidone or a copolymer containing a structural unit derived from vinylpyrrolidone or the like can be used. The content of the water-soluble polymer can be appropriately selected within the following range: The above-described effects produced by the water-soluble polymer do not interfere with the effects produced by other components or the extent that the processing fluid is not adversely affected.

(antifoaming agent)

The working fluid of the present invention may contain an antifoaming agent. By including the antifoaming agent in the working fluid of the present invention, bubbles generated in the working fluid can be reduced.

As the antifoaming agent, a known one can be used without particular limitation. Among them, those which are stably dispersed in the working fluid are preferred.

When the working fluid of the present invention is actually used for cutting, the lower limit of the content of the antifoaming agent is preferably 0.01% by mass or more, more preferably 0.02, based on the mass of the entire working fluid of the present invention (100% by mass). The mass% or more is more preferably 0.03 mass% or more, and the upper limit is preferably 0.06 mass% or less, more preferably 0.05 mass% or less, still more preferably 0.04 mass% or less. Further, in the case where a high concentration of the working fluid of the present invention is produced as described above, the upper limit of the content of the antifoaming agent is preferably based on the mass of the entire working fluid of the present invention (100% by mass). 0.6% by mass or less, more preferably 0.5% by mass or less, further preferably 0.4% by mass or less. When the content of the antifoaming agent is in the above range, the effect of containing the antifoaming agent can be exhibited. Further, when the content of the antifoaming agent is too large, the stability of the working fluid is lowered by separation of the working fluid or the like.

(other ingredients)

The working fluid of the present invention may also contain components other than the above components. It can add corrosion and discoloration to the workpiece without affecting the processing performance. Various additives that have adverse effects and do not affect the stability of the system after mixing. Examples of the additive as described above include a viscosity modifier, a pH adjuster, and an antioxidant. A viscosity adjuster, a pH adjuster, and an antioxidant can be used without any particular limitation. Among them, those which are soluble in water are preferred.

[Examples] <Production of processing fluid>

The water-soluble working fluid for fixed abrasive fine wire cutter of the present invention (Examples 1 to 4) and the water-soluble working fluid for fixed abrasive fine wire cutter other than the present invention were produced in the form shown in Tables 1 and 2. (Comparative Examples 1 to 13). The blending amounts of the respective components shown in Tables 1 and 2 are expressed by mass%. Further, Comparative Example 9 contained a working liquid containing 10% by mass of a synthetic (Synthetic) oil agent and 90% by mass of water manufactured by Yushiro Chemical Industries. Further, "C10 alcohol: EOPO" in Tables 1 and 2 means a copolymer of an alcohol having 10 carbon atoms and ethylene oxide and propylene oxide.

<evaluation>

The materials shown in Tables 1 and 2 were evaluated for the produced working fluids. "Appearance" means the result of visually observing the appearance of the working fluid. "pH" means the result of measuring the pH of the working fluid at 25 °C. "Cloud point" means the result of measuring the cloud point of the working fluid. "Processing Fluid Viscosity" means the viscosity of the working fluid measured at 25 ° C using a Brookfield viscometer. "Surface tension" means the use of the digital tension meter RTM-101 manufactured by Heshe Co., Ltd., and the static surface of the processing liquid at 25 ° C is measured by the Du Nouy ring method. The result of tension. "Electrical conductivity" is a result of measuring the electrical conductivity of the working fluid at 25 ° C using a conductivity meter ES-51 manufactured by Horiba, Ltd. "Quasi-use liquid viscosity" means the result of measurement performed in the following order. First, 10% by mass of cerium powder (having an average particle diameter of 1.5 μm) was added to each working solution, and after stirring and mixing, stainless steel balls (diameter: 2 mm) were placed, and stirred at 1000 rpm for 10 hours to prepare a quasi-use. liquid. Then, the stainless steel ball was filtered from the quasi-use liquid by a wire mesh (50 mesh), and the viscosity of the quasi-use liquid at 25 ° C was measured by a Brookfield viscometer. The "hydrogen generation amount" is a result of measuring the amount of hydrogen generated by heating 10 ml of the above-mentioned quasi-use liquid to 50 ° C in 30 minutes. The "hard agglomerate" was obtained by allowing the quasi-use liquid to stand in a glass container for one week, and removing the supernatant, and confirming the firmness of the precipitate layer remaining on the bottom of the glass container with a medicine spoon. The case where the sedimentation layer is firm, the spoon does not reach the bottom surface of the glass container is "x", and the case where the bottom surface is reached is "○". The "precipitation property" was allowed to stand in a glass container for one week, and it was judged visually based on the color of the supernatant liquid. The case where the supernatant was suspended by the powder was set to "X", and when it was clear, it was set to "○". "Corrosion" was evaluated by placing the cast iron cutting chips in a glass petri dish and injecting the working fluid until the cutting chips were completely submerged; thereafter, the lid was placed on the lid for 10 minutes and then placed on the lid. The culture dish was tilted to allow the processing liquid to flow out with a lid; then, the culture dish was placed on a water platform, and allowed to stand in this state for 24 hours, and the presence or absence of rust formation was observed. In the evaluation of the evaluation of corrosivity, "○" indicates that the generation of rust is less than 10% of the cast iron cutting debris.

As shown in Table 1, Examples 1 to 4 obtained good results in each of the evaluations of hard agglomeration, precipitability, and corrosivity. Further, in Examples 1 to 4, the amount of hydrogen generated was small, and the viscosity of the quasi-working liquid was low. On the other hand, as shown in Tables 1 and 2, Comparative Examples 1 to 13 were inferior in the evaluation of any of hard agglomerates, sedimentation, and corrosivity, or the viscosity of the quasi-working fluid became high. Or the amount of hydrogen generated is increased.

The present invention has been described above with respect to the embodiments which are considered to be the most practical and preferred embodiments, but the present invention is not limited to the embodiments disclosed in the specification of the present application, and does not violate the scope of the patent application and It is to be understood that the water-soluble working fluid for a fixed abrasive fine wire cutter according to the above-described changes is also included in the technical scope of the present invention within the scope of the gist of the invention.

(industrial availability)

The water-soluble working fluid for a fixed abrasive fine wire cutter of the present invention can be used when cutting a tantalum wafer with a fixed abrasive fine wire cutter.

Claims (9)

A water-soluble working fluid for a fixed abrasive fine wire cutter comprising (C) a carboxylic acid, (D) a compound which is dissolved in water to exhibit alkalinity, and (E) water, and a conductivity of 300 μS at 25 ° C / The viscosity of the quasi-use liquid formed at a temperature of 25 ° C or more and 3000 μS/cm or less at 25 ° C is 5 or more and 10 or less, and the viscosity of the quasi-use liquid formed by adding 10% by mass of the niobium powder having an average particle diameter of 1.5 μm is not satisfied at 25 ° C. 30mPa. s, the surface tension at 25 ° C is 20 mN / m or more and 50 mN / m or less. The water-soluble working fluid for a fixed abrasive fine-wire cutter according to the first aspect of the invention, which further comprises (A) a copolymer of alcohol, ethylene oxide and propylene oxide, and a polyoxyalkylene glycol. At least one or more nonionic surfactants selected from the group consisting of. The water-soluble working fluid for a fixed abrasive fine wire cutter according to the first aspect of the invention, further comprising (B) a glycol. A water-soluble working fluid for a fixed abrasive fine wire cutter according to the second aspect of the invention, which further comprises (B) a glycol. A water-soluble working fluid for a fixed abrasive fine wire cutter comprising: (A) at least one selected from the group consisting of alcohol, a copolymer of ethylene oxide and propylene oxide, and a polyoxyalkylene glycol 0.1% by mass or more and 8% by mass or less of the nonionic surfactant; (B) 0.1% by mass or more and 80% by mass or less of the diol; (C) 0.01% by mass or more and 5% by mass or less of the carboxylic acid; (D) 0.01% by mass or more and 7% by mass or less of the compound which is alkaline in water, and (E) water; and the electrical conductivity at 25 ° C is 300 μS/cm or more and 3000 μS/cm or less at 25 ° C The lower pH is 5 or more and 10 or less, and the viscosity of the quasi-use liquid formed by adding 10% by mass of the niobium powder having an average particle diameter of 1.5 μm and stirring is less than 30 mPa at 25 ° C. s. The water-soluble working fluid for a fixed abrasive fine wire cutter according to the fifth aspect of the invention, wherein the surface tension at 25 ° C is 20 mN/m or more and 50 mN/m or less. The water-soluble working fluid for a fixed abrasive fine wire cutter according to any one of claims 1 to 6, which further comprises a water-soluble polymer and/or an antifoaming agent. The water-soluble working fluid for a fixed abrasive fine-wire cutter according to any one of the first to sixth aspects of the present invention, wherein the mass of the water-soluble working fluid for the fixed abrasive fine wire cutter is 100% by mass or more (including the above) E) Water is 10% by mass or more and 99.7% by mass or less. The water-soluble working fluid for a fixed abrasive fine-wire cutter according to the seventh aspect of the invention, wherein the mass of the water-soluble working fluid for the fixed abrasive fine wire cutter is 100% by mass, and the (E) water is 10% by mass. The above and 99.7 mass% or less.