CN102527093A - Silicon crystal cutting fluid recovery method - Google Patents
Silicon crystal cutting fluid recovery method Download PDFInfo
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- CN102527093A CN102527093A CN2011100077917A CN201110007791A CN102527093A CN 102527093 A CN102527093 A CN 102527093A CN 2011100077917 A CN2011100077917 A CN 2011100077917A CN 201110007791 A CN201110007791 A CN 201110007791A CN 102527093 A CN102527093 A CN 102527093A
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Abstract
The invention provides a silicon crystal cutting fluid recovery method which comprises the following steps: diluting: adding water of which the percentage by weight is not less than 10wt% of the waste fluid into cut waste fluid obtained after the silicon crystal is cut to form mixed waste fluid; carrying out solid-liquid separation: carrying out solid-liquid separation on the mixed waste fluid to obtain aqueous cutting fluid of which the solid content is less than 10g/L; and heating and splitting the phase: under the condition of heating the aqueous cutting fluid to the temperature not less than 45DEG C, causing the cutting fluid and water in the aqueous cutting fluid to form a cutting liquid phase and an aqueous phase which are not mutually dissolved, and taking out the cutting fluid, thus finishing the recovery of the silicon crystal cutting fluid. In the silicon crystal cutting fluid recovery method, the silicon crystal cutting fluid can be effectively recovered without a pressurized or decompression air extracting device.
Description
One, technical field
The invention relates to a kind of recovery method of silicon wafer cutting liquid, be meant a kind of method of utilizing poor solubility to reclaim silicon wafer cutting liquid especially.
Two, background technology
Mostly general silicon crystal bar is to utilize multi-thread cutting mode to cut into Silicon Wafer, and supplying semiconductor or opto-electronics use, to make electronic product or solar cell.And for the process silicon wafer surface that reduces the scroll saw cutting produces defective or the situation of breaking, silicon crystal bar can use the cutting liquid with lubricated and cooling effect in cutting process, to reduce mechanical stress and the thermal stress damage in the cutting process; In addition, cutting liquid has good dispersiveness to the carborundum whetstone grain of high rigidity, can further improve the stability of silicon crystal bar cutting processing procedure.Yet; After the silicon crystal bar cutting, after materials such as the silicon of a large amount of cutting liquid, high rigidity whetstone grain, cutting loss, sawline metal mix, can form slimy cutting waste liquor and discharge; Cause the wafer manufacturing industry must face a large amount of pending waste water, manufacturing cost increases suddenly on the one hand; In addition, more run counter to the spirit of solar cell as clear energy sources.
Can know by present cutting waste liquor constituent analysis; Its polyethylene glycols that contains (polyglycols) cutting liquid accounts for 30-50wt%; And remaining solia particle mainly is the carborundum whetstone grain by granularity 5-15 μ m; And the silicon of granularity 0.1-5 μ m cutting loss, 0.5-2 μ m comes from the materials such as metal particle of stainless steel sawline.In fact, though these polyethylene glycols solution have mixed other solid particle, discharge with the mud state, its character is still very stable, has high recovery value.Along with silicon wafer demand in recent years heightens, the price of cutting liquid is also sharply soaring, so each producer falls over each other to research and develop related procedure or method, to reclaim the cutting waste liquor that this has high economic worth.
For example; China's CN101239246 publication number patent discloses a kind of method that reclaims silicon wafer cutting liquid, its mainly be utilize the 5-50% that adds earlier release agent in cutting waste liquor, utilize the mechanical separation mode to be divided into the rich silicon carbide slurry of 50-95%; And the poor silicon carbide suspension of 5-50%; Then in poor silicon carbide suspension, add stabilizing agent, and under 70-130 ℃ temperature, reacted 1-12 hour, be cooled to the temperature that is fit to mechanical filter after having reacted; Filter the solid particle of poor silicon carbide suspension, and the cutting liquid that obtains reclaiming; In addition; China CN101474511 publication number patent then discloses the another kind of method that reclaims silicon wafer cutting liquid; Its mainly be utilize add earlier be about waste liquid 3.5-4.5 visbreaking agent doubly in cutting waste liquor; Utilize the multiple times of filtration mode that solid particle is removed, the polyethylene glycol distillate that three grades of suspension that again filtration obtained at last utilize the vacuum distillation mode to obtain can be recycled.
Can know by above stated specification; The liquid of silicon wafer cutting at present mostly is to utilize repeatedly the Direct Filtration mode that the solia particle in the cutting waste liquor is separated with cutting liquid; Or utilize adding stabilizing agent or visbreaking agent; Shilling cutting waste liquor viscosity reduces, and the solia particle in the cutting liquid is leached, and re-uses the distillation mode and will cut liquid and isolate; Yet, because the viscosity of cutting waste liquor is very high, utilize the mode of Direct Filtration that solia particle in the cutting waste liquor is separated with cutting liquid, not only need use the high pass filter air extractor auxiliary, its processing cost is high and time-consuming, and filter material is damaged easily; Though can reduce filtration time after adding visbreaking agent, later use distillation mode reclaims cutting liquid, then because the continuous high temperature of distillation causes the rotten problem of cutting liquid oxidation easily.In addition; Though utilize the mode of decompression or vacuum distillation to help to remove at a lower temperature the visbreaking agent of sneaking into, need to use the device such as bleed that reduces pressure, and removal speed be slow; The problems such as water content of wayward recovery cutting liquid also cause cutting liquid and utilize usefulness to successively decrease again.Therefore, how to develop one easyly, economy, and can effectively reclaim the method for silicon wafer cutting liquid is still constantly made great efforts one of direction of developing for present industry.
Three, summary of the invention
The present invention's purpose is promptly providing a kind of simple and can reclaim the method for silicon cutting liquid fast.
So the present invention is a kind of silicon wafer cutting liquid recovery method, comprise a dilution step, a solid-liquid separation step and a heating phase-splitting step.
This dilution step is to contain behind the silicon wafer in a cutting in the cutting waste liquor of solia particle such as carborundum, silicon and metal and cutting liquid to add the water that percentage by weight is not less than the 10wt% of this cutting waste liquor, dilution back formation one mixed waste liquor.
This solid-liquid separation step is that this mixed waste liquor is carried out Separation of Solid and Liquid, makes solid, fluid separation applications in the mixed waste liquor, obtains a moisture cutting liquid.
This heating phase-splitting step is this moisture cutting liquid to be heated to temperature be not less than under 45 ℃ the condition; Make cutting liquid and water nationality in this moisture cutting liquid cause changes in solubility by variations in temperature; And this cutting liquid of order and water form immiscible cutting liquid phase and water; Should cut liquid afterwards and take out, and obtain one and reclaim cutting liquid, promptly accomplish this silicon wafer cutting liquid recovery method.
The present invention's effect is: utilize temperature control; The cutting liquid and the water that dissolve each other under the order script room temperature form immiscible cutting liquid phase and water, can will cut liquid and isolate, and not only method is simple; Need not use highly energy-consuming and expensive equipment; And can remove a large amount of water fast, the cutting liquid water content that is reclaimed is low and stable, so recycling usefulness is very high.
Four, the specific embodiment
Address other technology contents, characteristics and effect about before the present invention, in the detailed description of following preferred embodiment, can clearly appear.
One preferred embodiment of silicon wafer cutting liquid recovery method of the present invention comprises a dilution step, a solid-liquid separation step, and a heating phase-splitting step.
This dilution step is that a cutting waste liquid is added the water that percentage by weight is not less than this cutting liquid 10wt%, and the dilution back forms a mixed waste liquor.
This cutting waste liquor is after utilizing cutting liquid mixing high rigidity carborundum whetstone particle shape to become grinding milk; Collect behind the cooperation stainless steel sawline cutting silicon crystal bar and get; Wherein contain liquid and solia particle two large divisions; Liquid mainly is polyethylene glycols cutting liquid, and solia particle then is carborundum whetstone grain and the polysilicon or the materials such as monocrystalline silicon particle, sawline metal of cutting loss in the grinding milk.In present embodiment, the about 700g/L of the solid content in this cutting waste liquor.
Because the cutting liquid viscosity that has mixed behind a large amount of solia particles is very high, causes follow-up Separation of Solid and Liquid operating difficulties.Therefore, this dilution step will add under the room temperature water that dissolves each other with cutting liquid earlier, the viscosity of this cutting waste liquor is reduced, and obtain one have a low-viscosity mixed waste liquor.
What deserves to be mentioned is; Under room temperature, when the water yield that adds this cutting waste liquor is low, because water can produce hydrogen bond between the main component polyethylene glycol compounds of cutting liquid; Cause forming intermolecular linkage knot and prolong its strand, can cause mixed waste liquor to add low amounts of water on the contrary after viscosity rise; Therefore, add cutting waste liquor the water yield otherwise less than the 10wt% of this cutting waste liquor, to obtain to have the mixed solution of low-viscosity; Preferably, the water yield of this adding is not less than the 30wt% of this cutting waste liquor, and more preferably, the water yield of this adding is not less than the 50wt% of this cutting waste liquor, and the mixed waste liquor viscosity that forms is not more than the viscosity of this cutting liquid.
This solid-liquid separation step is that aforementioned mixed waste liquor is carried out Separation of Solid and Liquid, and the isolated moisture cutting fluid solid content of control is not more than 10g/L.
This solid-liquid separation step can make this mixed waste liquor with low-viscosity carry out Separation of Solid and Liquid, and obtain the moisture cutting liquid that a solid content is not more than 10g/L via modes such as settling tank, the machine that concentrates, centrifugal or filtrations.
Because this mixed waste liquor is the thinlyfluid after the water dilution, therefore, after leaving standstill 10hr, promptly can be observed tangible Separation of Solid and Liquid interface, and is enough to obtain the moisture cutting liquid that a large amount of solid contents are not more than 10g/L; Time of repose is longer, and the Separation of Solid and Liquid interface is clearer, and the solid content of the moisture cutting liquid of being obtained is lower, preferably, leaves standstill after the 24hr ground sedimentation of solia particle greater amount; More preferably, leave standstill 48hr after, most of particles all are deposited at the bottom of the pond.Be noted that; When the solid content of this moisture cutting liquid during greater than 10g/L; In follow-up phase separation; Can in heating process, form the interference of convection current disturbance effect because of those solia particles, so that can't make this cutting liquid form immiscible two phases effectively in water, and then influence the recovery usefulness of this cutting liquid.
This heating phase-splitting step is this moisture cutting liquid to be heated to temperature be not less than 45 ℃, and this cutting liquid of order and water form immiscible cutting liquid phase and water, and should cut liquid separates with water, and accomplishes the recovery of cutting liquid.
Under the normal pressure, polyethylene glycol compounds in this moisture cutting liquid and water are when room temperature, owing to can produce hydrogen bond action, formation homogeneous phase solution each other therefore can dissolve each other; And when temperature raises, then since polyethylene glycol compounds and the hydrogen bond between the water in this moisture cutting liquid be destroyed, so the solubility decline of polyethylene glycol compounds in water.Nationality of the present invention is by the characteristic that causes changes in solubility between water and this polyethylene glycols cutting liquid because of variations in temperature, proposes a kind of simple and can reclaim the method that silicon wafer cuts liquid fast.Utilize the high cutting waste liquor of water dilution solid content; Nationality is by water and the high character of polyethylene glycols cutting liquid intersolubility under normal temperature; Reduce the viscosity of cutting waste liquor significantly; So that the solid particle in the cutting waste liquor removes effectively, obtain the moisture cutting liquid that solid content is not more than 10g/L in the Separation of Solid and Liquid process; Then, utilize temperature control again, with the temperature increase of moisture cutting liquid to being not less than 45 ℃; Nationality is by the polyethylene glycol compounds and the hydrogen bond between the water that heat up to destroy in the moisture cutting liquid, and lets the solubility of polyethylene glycol in water descend, and then is separated; Form immiscible two phases (cutting liquid phase and water); So need not use the power consumption unit with aqueous vaporization, need can not be the cutting liquid recovery of polyethylene glycols with this principal component promptly by the air extractor of costliness also.
Preferably, this heating phase-splitting step is under temperature is not less than 50 ℃ condition, to carry out; More preferably, this heating phase-splitting step is to carry out under 50-70 ℃ condition in temperature.Through detecting water content (moisture titrator by the recovery cutting liquid after this preferred embodiment recovery of the present invention; Metrohm 870KF Titrino plus) and viscosity (viscosimeter; Brookfield LVDV-E; 25 ℃) after, its moisture obtained at 0.2-2wt%, and its viscosity and original cutting liquid phase ratio at 25 ℃ fluctuates between 1-4%.
In sum; Nationality of the present invention is by water and the dissolubility property of polyethylene glycols cutting liquid under different temperatures; Utilize water to be dilution, nationality significantly reduces the viscosity of cutting waste liquor by water and the intersolubility of polyethylene glycols cutting liquid under normal temperature; Therefore, can effectively the solia particle in the cutting waste liquor be removed; Utilize temperature control again, destroy polyethylene glycol compounds and the hydrogen bond between the water in the moisture cutting liquid, and let the solubility of polyethylene glycol in water descend, be separated; And then form immiscible two phases; Promptly can be with the cutting liquid recycling of polyethylene glycols, not only method is simple, and does not need air extractor; Or highly energy-consuming and expensive equipment such as evaporation, distillation; Can remove a large amount of water quickly, the cutting liquid water content that is reclaimed is low and stable, so can reach the present invention's purpose really.
The above person of thought; Be merely the present invention's preferred embodiment and concrete example; When the practical range that can not limit the present invention with this, the simple equivalent of promptly doing according to claim of the present invention and invention description generally changes and modifies, all still within the patent covering scope of the present invention.
Claims (7)
1. a silicon wafer cuts the liquid recovery method, comprises:
One dilution step adds the water that percentage by weight is not less than the 10wt% of this cutting waste liquor with the cutting waste liquor that contains solia particle and cutting liquid behind the cutting silicon wafer, and dilution forms a mixed waste liquor;
One solid-liquid separation step is carried out Separation of Solid and Liquid with this mixed waste liquor, obtains the moisture cutting liquid of a solid content less than 10g/L;
One heating phase-splitting step; This moisture cutting liquid is heated to temperature to be not less than under 45 ℃ the condition; Make cutting liquid and water nationality in this moisture cutting liquid cause changes in solubility, and make this cutting liquid and water form immiscible cutting liquid phase and water, should cut liquid afterwards and take out by variations in temperature; Obtain one and reclaim cutting liquid, promptly accomplish this silicon wafer cutting liquid recovery method.
2. according to claim 1 silicon wafer cutting liquid recovery method, wherein, this solid-liquid separation step be utilize settling tank, the pond of concentrating, centrifugal, or filter type.
3. according to claim 1 silicon wafer cutting liquid recovery method, wherein, the water that this dilution step adds cutting waste liquor is not less than 30wt%, and the viscosity of this mixed solution is not more than the viscosity of this cutting liquid.
4. according to claim 1 silicon wafer cutting liquid recovery method, wherein, this heating steps is under normal pressure, and this moisture cutting liquid is heated under the temperature conditions that is not less than 50 ℃.
5. like the method for the said silicon wafer cutting liquid recovery of claim 4, wherein, this heating steps is that this filtered fluid is heated to temperature between 50-70 ℃.
6. according to claim 1 silicon wafer cutting liquid recovery method, wherein, this is not more than 4wt% through the resulting recovery cutting of heating phase-splitting step liquid water content.
7. the silicon wafer cutting liquid recovery method of claim 6, wherein, this is not more than 3wt% through the resulting recovery cutting of heating phase-splitting step liquid water content.
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| CN2011100077917A CN102527093A (en) | 2011-01-02 | 2011-01-02 | Silicon crystal cutting fluid recovery method |
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| CN2011100077917A CN102527093A (en) | 2011-01-02 | 2011-01-02 | Silicon crystal cutting fluid recovery method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103435210A (en) * | 2013-07-19 | 2013-12-11 | 江苏吉星新材料有限公司 | Cutting fluid recycling method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01115414A (en) * | 1987-10-27 | 1989-05-08 | Kakooki:Kk | Quality control device for grease removal and washing solvent |
| CN101239246A (en) * | 2008-02-20 | 2008-08-13 | 江南大学 | Method for recovering cutting solution from by-product of silicon chip cutting processing |
| CN101817526A (en) * | 2010-04-08 | 2010-09-01 | 浙江源盛硅晶材料有限公司 | Method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid |
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2011
- 2011-01-02 CN CN2011100077917A patent/CN102527093A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01115414A (en) * | 1987-10-27 | 1989-05-08 | Kakooki:Kk | Quality control device for grease removal and washing solvent |
| CN101239246A (en) * | 2008-02-20 | 2008-08-13 | 江南大学 | Method for recovering cutting solution from by-product of silicon chip cutting processing |
| CN101817526A (en) * | 2010-04-08 | 2010-09-01 | 浙江源盛硅晶材料有限公司 | Method for recovering polyethylene glycol and silicon carbide from silicon crystal cutting waste liquid |
Non-Patent Citations (1)
| Title |
|---|
| 邹华生等: "油包水微乳液体系的稳定性分析", 《华南理工大学学报（自然科学版）》, vol. 36, no. 3, 31 March 2008 (2008-03-31), pages 32 - 36 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103435210A (en) * | 2013-07-19 | 2013-12-11 | 江苏吉星新材料有限公司 | Cutting fluid recycling method |
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Application publication date: 20120704 |