JP2003082381A - Nonflammable aqueous cutting fluid composition and nonflammable aqueous cutting fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonflammable aqueous cutting fluid composition which has good dispersibility of abrasive grains and no problem of flammability even when used in cutting processing of hard brittle materials, and is easy to wash with water. SOLUTION: The nonflammable aqueous cutting fluid composition comprises a polycarboxylic acid based polymeric compound having a weight average molecular weight of 1,000-200,000 and/or its salt in an amount of 5-45 wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-flammable water-based cutting fluid composition and a non-flammable water-based cutting fluid. More specifically, it is a semiconductor crystal material such as single crystal silicon or polycrystalline silicon, quartz, crystal, ceramics, or the like. The present invention relates to a water-based cutting fluid suitable for cutting an ingot, and a slurry non-flammable water-based cutting fluid mixed with abrasive grains.

[0002]

2. Description of the Related Art Conventionally, in cutting fluids for cutting hard and brittle materials such as silicon ingots, as an abrasive dispersion medium,
A non-aqueous cutting fluid mainly composed of mineral oil is used. This non-aqueous cutting fluid is a slurry in which abrasive grains such as silicon carbide are dispersed in cutting oil at a ratio of 1: 1 (weight ratio), and this slurry is continuously supplied to the cutting surface. A chlorine-based organic solvent such as trichloroethane or methylene chloride or a high-concentration nonionic surfactant is used as a cleaning liquid for cleaning the cut wafer.

However, since mineral oil is a flammable dangerous substance, explosion proof equipment is required and the storage quantity is limited, which may cause problems in environmental protection and manufacturing control. Further, the above-mentioned chlorine-based organic solvent cleaning agent used for cleaning a wafer cut with a mineral oil has a carcinogenic property, which is a safety and health problem. In addition, its use has been banned in recent years because it is the main cause of air pollution and destruction of the ozone layer. A nonionic surfactant is used as an alternative cleaning agent.
Cleaning of this nonionic surfactant requires a large cleaning facility due to its low cleaning power, and since it needs to be used at a high concentration, it causes problems in wastewater treatment and disposal. There is.

On the other hand, a glycol-type water containing water-soluble ethers such as polyoxyalkylene glycol and its derivatives as a main component, which does not contain mineral oil as a main component and can be washed with water after the cutting step, is used. Melting water-soluble cutting fluid (JP-A-3-181598 and JP-A-11-1)
98016) is proposed.

[0005]

However, the glycol type water-soluble cutting fluid needs to be mixed with water in order to eliminate the flash point. However, when the water content is low, it causes flammability and the water content. When a large amount is mixed, the dispersibility of the abrasive grains deteriorates, which causes problems in manufacturing control. Also,
Even if the glycol type water-soluble cutting fluid is easy to wash with water, the waste water load of the washing water is high and there is a problem in waste fluid treatment.

[0006]

The present invention has been made by paying attention to such conventional problems, and a large amount of water was added by using a specific polycarboxylic acid type polymer compound. The composition also has good dispersibility of abrasive grains, has no problem of flammability even when used for cutting hard and brittle materials, and can be easily washed with water, and has good wastewater treatability. It is possible to provide a cutting fluid composition and a non-flammable water-based cutting fluid.

That is, the non-flammable water-based cutting fluid composition of the present invention comprises a polycarboxylic acid polymer compound having a weight average molecular weight of 1,000 to 200,000 and / or a salt thereof in an amount of 5 to 4
It is characterized by containing 5% by weight.

It is considered that the polycarboxylic acid type polymer compound is adsorbed on the abrasive grains and exhibits a stable dispersion effect due to the protective colloid effect. Further, since the salt of the polycarboxylic acid-based polymer compound is provided with ionicity, it is considered that an electrostatic repulsion force is generated and further excellent dispersibility is obtained.

When the molecular weight or blending amount of this polycarboxylic acid type polymer compound is low, a uniform protective colloid layer is not formed on the surface of the particles, the repulsive force between particles becomes weak, and the dispersibility and redispersibility are reduced. Will be worse. In addition, when the molecular weight exceeds 200,000, an aggregation effect appears,
It is considered that the redispersibility decreases.

The polycarboxylic acid type polymer compound and /
Alternatively, the salt thereof is a polymer prepared from one or more monomers selected from the group consisting of acrylic acid, maleic acid and methacrylic acid, an alkali metal salt of the polymer, an onium salt of the polymer and one of these. It is preferably selected from the group consisting of one kind or a mixture of two or more kinds.

The polycarboxylic acid type polymer compound and / or its salt is preferably a polymer represented by the general formula (1) of Chemical formula 2.

[0012]

[Chemical 2]

In the general formula (1), R is a hydrogen atom or a methyl group, and M ₁ , M ₂ , and M ₃ are any of a hydrogen atom, an alkali metal atom or onium. It may be the same or different from each other. n is an integer of 1 or more,
m is an integer of 0 or more.

The non-flammable water-based cutting fluid of the present invention is characterized by containing the above non-flammable water-based cutting fluid composition and abrasive grains.

Here, the grain size of the abrasive grains is 0.5 to 50.
It is preferably μm. Further, a cutting fluid in which a non-flammable water-based cutting fluid composition and abrasive grains are dispersed in a weight ratio of 1: 0.5 to 1: 1.5 is preferable.

The non-flammable water-based cutting fluid of the present invention is preferably used for a wire saw or a band saw, and particularly for cutting an ingot made of a hard and brittle material. Examples of the hard and brittle material include materials selected from silicon, quartz and quartz.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

As the polycarboxylic acid type high molecular compound used in the present invention, a homopolymer or copolymer of acrylic acid, maleic acid or methacrylic acid, or ethylene, propylene, styrene, methacrylic acid ester, maleic acid monoester, maleic acid or a homopolymer or copolymer thereof. Copolymers with acid diesters, vinyl acetate and the like can be used. Further, an alkali metal salt and / or onium salt of the above polycarboxylic acid type polymer compound can also be used. Here, as the type of salt, salts of metal ions such as sodium, potassium and lithium, ammonia, monoethanolamine, diethanolamine, triethanolamine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, methylethanolamine , Salts of onium ions such as dimethylethanolamine, methyldiethanolamine, ethylethanolamine, diethylethanolamine and ethyldiethanolamine. Of these salts, the preferred ones are sodium, potassium, ammonia, monoethanolamine and diethanolamine salts.

Among the above-mentioned polycarboxylic acid type polymer compounds, particularly preferably used are homopolymers of acrylic acid represented by the general formula (1) of the above chemical formula 2 and / or acrylic acid and maleic acid. Alkali metal salt and / or onium salt of the copolymer of

The weight average molecular weight of the polycarboxylic acid type polymer compound and / or its salt is 1,000 to 200,000.
0 is preferable, but 5,000 to 20,000
The product is easy to handle, and an appropriate viscosity can be obtained when it is made into an aqueous solution. If the molecular weight is less than 1,000, the dispersibility of the abrasive grains is low, and a compounding amount of more than 50% by weight is required, and the waste water load increases. When the molecular weight is more than 200,000, it is necessary to reduce the compounding amount in order to obtain an appropriate viscosity, and in addition, the dispersibility of abrasive grains is lowered.

The lower limit of the compounding amount of the polycarboxylic acid type polymer compound and / or its salt is 5% by weight or more, preferably 2
It is 0% by weight or more, and the upper limit is 45% by weight or less, preferably 40% by weight or less. If the content is less than 5% by weight, sufficient dispersibility of abrasive grains cannot be obtained, and if it exceeds 45% by weight, the viscosity of the cutting fluid increases and it becomes difficult to mix the abrasive grains.
Continuous supply to the cutting equipment is also impossible.

The water content of the non-flammable water-based cutting fluid is 5
It is 5 to 95% by weight, and if it is less than 55% by weight, the polycarboxylic acid salt type polymer compound cannot be uniformly dissolved, which is not preferable. In addition, the water content is 55 to 95
By blending in the range of wt%, even in the case of washing the cut object (wafer etc.) after cutting, it becomes possible to remove the slurry of the non-flammable water-based cutting fluid of the present invention with only water, and the washing can be performed. It will be easy. If desired, various additives may be added to the non-flammable water-based cutting fluid of the present invention. Examples of such addition aids include water-soluble solvents, lubricants, viscosity modifiers, anti-corrosion agents for non-ferrous metals, defoaming agents and the like. Examples of water-soluble solvents include ethylene glycol,
Diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, hexylene glycol, glycerin, polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymer, hexylene glycol, glycerin, 1,
3-propanediol, 1,4-butanediol, 1,
6-hexanediol, pentaerythritol, sorbitol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
Mention may be made of diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether and mixtures thereof. Also, as a lubricant,
Examples thereof include nonionic surfactants, anionic surfactants, fatty acids and fatty acid polycondensates. Examples of the viscosity modifier include bentonite, aqueous silica sol, polyvinylpyrrolidone, carboxymethyl cellulose and the like. Examples of the anticorrosive agent for non-ferrous metals include benzotriazole compounds, and examples of the defoaming agent include silicone compounds, acetylene diol compounds, polyglycol compounds, and alcohols.

The abrasive grains to be dispersed in the non-flammable water-based cutting fluid of the present invention are not particularly limited, and examples thereof include silicon carbide, aluminum oxide, zirconium oxide, silicon dioxide, cesium dioxide and diamond. The average grain size of the abrasive grains is preferably 0.5 to 50 μm, more preferably 5
˜30 μm. When the average particle size of the abrasive grains exceeds 50 μm, the sedimentation speed of the abrasive grains is increased and it becomes difficult to disperse the abrasive grains. If the average grain size of the abrasive grains is smaller than 0.5 μm, the cutting ability of the cutting fluid is reduced, which is not preferable. The lower limit of the compounding ratio of the abrasive grains to the non-flammable water-based cutting fluid 1 is 0.5 (weight ratio) or more, preferably 0.8 or more. Further, the upper limit of the mixing ratio of the abrasive grains is 1.5 (weight ratio) or less, and preferably 1.2 or less. If the mixing ratio of the abrasive grains is less than 0.5, the amount of abrasive grains in the slurry is too small,
It takes a long time for cutting. Further, if the mixing ratio of the abrasive grains exceeds 1.5, the dispersibility of the abrasive grains is poor and it becomes difficult to continuously supply the cutting fluid in the form of slurry of the present invention to the cutting device, which is not preferable.

The non-flammable water-based cutting fluid of the present invention is used for cutting hard and brittle materials, and the hard and brittle materials are not particularly limited, but single crystal silicon, polycrystalline silicon, quartz, quartz, glass,
It can be preferably used for hard and brittle materials such as gallium-arsenic and ceramics, and more preferably applied to a single crystal silicon ingot or a quartz (quartz) ingot. Further, the non-flammable water-based cutting fluid of the present invention uses free abrasive grains,
Any type of cutting device can be used as long as it is a cutting device for cutting hard and brittle materials, but preferable cutting devices include, for example, a wire saw and a band saw.

[0025]

EXAMPLES Next, the present invention will be explained based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Examples 1 to 14 and Comparative Examples 1 to 7) Table 1
And each component shown in Table 2 was mix | blended in the ratio described, and the cutting fluid composition was obtained. A cutting fluid was prepared by adding abrasive grains to the obtained cutting fluid composition, and the dispersibility of each cutting fluid, redispersibility, viscosity change, cutting processing accuracy, washability, and wastewater treatability were determined as follows. The results are shown in Tables 3 and 4.

[0027]

[Table 1]

[0028]

[Table 2]

(Dispersibility and Redispersibility of Abrasive Grains) Tables 1 and 2
500 g of the cutting agent composition and silicon carbide abrasive grains (GP
# 800, made by Fujimi Incorporated) 500
g and 1,000 ml in a plastic container and store at room temperature (25
(C) using a homodisper (manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotation speed of 3,000 rpm for 3 minutes to obtain a uniform slurry-like non-flammable water-based cutting fluid.

100 ml of this water-based cutting fluid was put into a 100 ml Nessler tube (diameter 24 mm, height 200 mm),
At 1 hour, 6 hours, 24 hours and 48 hours after standing, the volume of the lower layer abrasive grains was measured and the sedimentation state was observed. It can be judged that the lower layer having a large capacity has a small amount of upper separated water and is excellent in the dispersibility of the abrasive grains.

The redispersibility of the abrasive grains was judged by the following criteria from the fluidity of the abrasive grain layer after tilting the Nessler tube containing the slurry 48 hours after standing still.

[0032] ◎… The entire abrasive grain layer flows smoothly ○: The entire abrasive grain layer slowly flows △: Only the upper part of the abrasive layer flows X: The abrasive grain layer hardly flows.

As is clear from Tables 3 and 4, the non-flammable water-based cutting fluid of each example exhibits a stable dispersion effect comparable to the mineral oil-based cutting fluid (Comparative Example 7). This indicates that the polycarboxylic acid type polymer compound blended in the non-flammable water-based cutting fluid of each example is adsorbed on the abrasive grain to form a protective colloid. Further, since the alkali metal salt and onium salt of the polycarboxylic acid type polymer compound have ionicity, it is considered that electrostatic repulsion force is exerted, and further excellent dispersibility is obtained. . When the polycarboxylic acid polymer compound has a certain molecular weight or less or when the compounding amount is low, it is considered that a uniform protective colloid layer is not formed on the particle surface and the repulsive force between particles becomes weak, Dispersibility and redispersibility are reduced. Further, when the molecular weight exceeds 200,000, the aggregating action is exhibited and the redispersibility is deteriorated.

(Viscosity Change) 500 g of the cutting fluid composition listed in Tables 1 and 2 and silicon carbide abrasive grains (GP # 800, manufactured by Co., Ltd.)
Made by Fujimi Incorporated) 500g and 1,00
Collect in a 0 ml poly container and rotate at room temperature (25 ° C) with a homodisper (manufactured by Tokushu Kika Kogyo Co., Ltd.) rotation speed of 3,000r.
The mixture was stirred at pm for 3 minutes to obtain a uniform slurry-like non-flammable water-based cutting fluid. The viscosity of this water-based cutting fluid at 25 ° C. was measured with a BM type viscometer. Next, using a homomixer (disper blade), the mixture was stirred at a rotation speed of 10,000 rpm for 1 hour, adjusted to 25 ° C., and then the viscosity was measured.
The rate of change in viscosity before and after stirring = (viscosity after stirring for 1 hour at 10,000 rpm) / (viscosity before stirring) was determined, and the effect of shearing force was investigated. It is shown that the closer the viscosity change rate is to 1, the smaller the viscosity change at the time of cutting an ingot or the like and the more stable workability can be obtained.

As is apparent from Tables 3 and 4, when the non-flammable water-based cutting fluid of each example is used, the viscosity change is smaller than that of the cutting fluid of the comparative example, and the mineral oil-based cutting fluid ( It can be seen that it has a viscosity stability equal to or higher than that of Comparative Example 7).

(Cutting accuracy) The cutting fluid compositions shown in Tables 1 and 2 and silicon carbide abrasive grains (GP # 800, manufactured by Fujimi Incorporated) are mixed by stirring at a ratio of 1: 1 (weight ratio). A non-flammable water-based cutting fluid in the form of a uniform slurry was obtained. Using this cutting fluid, a 6-inch diameter single crystal silicon ingot was cut by a wire saw cutting device having a wire diameter of 180 μm, and the cutting accuracy of the cut wafer was evaluated.

The processing accuracy is measured by measuring the warp of the wafer (WARP, the maximum value of the height difference between the central portion and the outer peripheral portion at a total of 5 points), and obtaining the average value of 10 wafers, and the cutting processing accuracy based on the following criteria. Was judged.

[0038] ◎ ... 0 μm or more and less than 10 μm ○: 10 μm or more and less than 20 μm Δ: 20 μm or more and less than 30 μm X: 30 μm or more.

As is clear from Tables 3 and 4, when the non-flammable water-based cutting fluid of each example is used, the cutting precision is higher than that of the comparative example and the mineral oil-based cutting fluid is used. It can be seen that cutting processing accuracy equal to or higher than that of (Comparative Example 7) can be exhibited.

(Cleanability) 1,000 parts of 500 g of the cutting fluid composition shown in Tables 1 and 2 and 500 g of silicon carbide abrasive grains (GP # 800, manufactured by Fujimi Incorporated).
Collect in a ml plastic container and homogenize at room temperature (25 ° C) (disper blade) at a rotation speed of 3,000 rpm for 3 times.
After stirring for a minute, a uniform slurry-like non-flammable water-based cutting fluid was obtained.

The cutting liquid was applied to a silicon wafer and a quartz wafer, dried at 80 ° C. for 1 hour, and used as a simulated sample after cutting. The wafer of this simulated sample was washed with running water (room temperature 25 ° C.) for 3 minutes, and the washability was judged according to the following criteria.

[0042] ○: Those that can be washed off without any abrasive residue ×: Abrasive particles remain and cannot be washed off.

As is clear from Tables 3 and 4, when the non-flammable water-based cutting fluid of each example is used, and when the silicon wafer and the quartz wafer are both used, the cutting fluid of the comparative example is used. Detergency equal to or higher than that of is obtained. Incidentally, the mineral oil-based cutting fluid (Comparative Example 7) could not be washed with water, and the cleaning performance was evaluated as x. However, in this case, the abrasive grains were not removed at all. The detergency is obviously inferior to that of the example.

(Wastewater Treatment) A 0.1% aqueous solution of the cutting fluid composition listed in Tables 1 and 2 was prepared, and its chemical oxygen demand (COD) and biochemical oxygen demand generation (BOD) were measured. It was measured, and the wastewater treatability was judged according to the following criteria.

[0045] Good: COD and BOD less than 1,000 mg / l X ... COD and BOD are 1,000 mg / l or more.

As can be seen from Tables 3 and 4, the use of the non-flammable water-based cutting fluid of each example shows a better waste water treatment than the cutting fluid of the comparative example. The mineral oil-based cutting fluid (Comparative Example 7) is treated as industrial waste, and wastewater treatment is impossible. Considering the processing cost and the effect on the environment, the superiority of each embodiment is clear.

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

The non-flammable water-based cutting fluid composition of the present invention comprises:
Since it contains a polycarboxylic acid type polymer compound and / or its salt, the dispersibility of abrasive grains is good even when a large amount of water is added, and the problem of flammability during cutting of hard and brittle materials It can be used without any safety and health problems.

Further, since the non-flammable water-based cutting fluid of the present invention contains abrasive grains in the above composition, it can be continuously supplied to a cutting machine such as a wire saw or band saw, so that a wafer with high processing accuracy can be obtained. The cutting can be done. Further, the processed object (wafer, etc.) after processing can be easily washed with water, and the wastewater treatment property is also good.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C10M 145/14 C10M 145/14 145/16 145/16 // C10N 10:02 C10N 10:02 10:06 10:06 10:08 10:08 20:04 20:04 20:06 20:06 Z 30:00 30:00 Z 30:04 30:04 40:22 40:22 F term (reference) 4H104 AA04C AA13C AA21C AA22C CB08A CB08C CB09A CB09C EA03A EA08C FA01 FA03 FA04 LA02 LA20 PA22 RA01

Claims (9)

[Claims] 1. A weight average molecular weight of 1,000 to 200,
Non-flammable water-based cutting fluid composition containing 5 to 45% by weight of polycarboxylic acid type polymer compound and / or salt thereof. 2. A polymer prepared from one or more monomers selected from the group consisting of acrylic acid, maleic acid and methacrylic acid, wherein the polycarboxylic acid-based polymer compound and / or its salt is a polymer. Alkali metal salts of polymers, onium salts of said polymers and one or two of these
The non-flammable water-based cutting fluid composition according to claim 1, which is selected from the group consisting of a mixture of one or more kinds. 3. The non-flammable water-based cutting fluid composition according to claim 1, wherein the polycarboxylic acid-based polymer compound and / or its salt is a polymer represented by the general formula (1) of Chemical formula 1. [Chemical 1] (In the formula, R is a hydrogen atom or a methyl group, M ₁ , M ₂ , and M ₃ are either a hydrogen atom, an alkali metal atom or onium and may be the same or different, and n is 1 The above integers and m are integers of 0 or more.) 4. A non-flammable water-based cutting fluid containing the non-flammable water-based cutting fluid composition according to claim 1 and abrasive grains. 5. The non-flammable water-based cutting fluid according to claim 4, wherein the abrasive grains have a particle diameter of 0.5 to 50 μm. 6. The weight ratio of the non-flammable water-based cutting fluid composition according to any one of claims 1 to 3 and abrasive grains is 1: 0.5 to.
The non-flammable water-based cutting fluid according to claim 4 or 5, which is dispersed at a ratio of 1: 1.5. 7. The non-flammable water-based cutting fluid according to claim 4, which is used for a wire saw or a band saw. 8. The non-flammable water-based cutting fluid according to claim 4, which is used for cutting an ingot made of a hard and brittle material. 9. The non-flammable water-based cutting fluid according to claim 8, wherein the hard and brittle material is selected from silicon, quartz and quartz.