CN115397616A - Method for manufacturing high-porosity ceramic bond grindstone - Google Patents
Method for manufacturing high-porosity ceramic bond grindstone Download PDFInfo
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- CN115397616A CN115397616A CN202080099424.1A CN202080099424A CN115397616A CN 115397616 A CN115397616 A CN 115397616A CN 202080099424 A CN202080099424 A CN 202080099424A CN 115397616 A CN115397616 A CN 115397616A
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- grinding stone
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D18/00—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
- B24D18/0009—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for using moulds or presses
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D18/00—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
- B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
- B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
- B24D3/04—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic
- B24D3/14—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic ceramic, i.e. vitrified bondings
- B24D3/18—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic ceramic, i.e. vitrified bondings for porous or cellular structure
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- Polishing Bodies And Polishing Tools (AREA)
Abstract
Provided is a method for producing a vitrified bonded grinding stone, which can stably produce a vitrified bonded grinding stone having a high porosity achieved by interconnected pores. In the freeze vacuum drying step P3, the formed body 28 in which the plurality of frozen particles 30 are generated is placed in a vacuum, so that the frozen particles 30 in the formed body 28 are sublimated and dried, and the frozen particles 30 are sublimated to form the communicating pores 32. Since the pores 32 formed in this way do not disappear during production, and shrinkage of the molded body 28 is suppressed, the high-porosity vitrified bond grinding stone 10 in which high porosity is realized by the communicating pores 32 can be stably produced.
Description
Technical Field
The present invention relates to a method for producing a vitrified bonded grinding stone having a high porosity by communicating pores.
Background
In general, in order to improve the coercive force of abrasive grains by bonding the abrasive grains with a vitrified bond and to satisfactorily generate the self-sharpening action of the cutting edge of the abrasive grains when grinding a semiconductor wafer, a porous vitrified bond grinding stone has been proposed which has independent pores and realizes a high porosity of about 75 to 95 volume%. For example, the ceramic bond grindstones described in patent documents 1 and 2 are of this kind.
According to the ceramic bond grinding stone with high porosity, the advantages are as follows: since the abrasive grains have a high porosity, the abrasive grains can have a self-sharpening action on the cutting edge, thereby improving the grinding performance, and since the high porosity is achieved by the independent pores, the grinding stone can have a sufficient strength, and can be ground at a sufficient grinding pressure.
The high porosity vitrified bonded grinding stone described in patent document 1 is produced by the following method: the method for producing the porous abrasive particles includes the steps of press-molding a raw material for a grinding stone obtained by kneading an organic pore-forming agent such as polystyrene particles with abrasive grains and a ceramic binder to produce a molded body, and firing the molded body to burn off the organic pore-forming agent. Therefore, in the high-porosity vitrified bond grinding stone obtained by firing, a considerable part of the pores is closed pores which are independent pores. Therefore, the chips generated during grinding may accumulate in the independent air holes and sufficient grinding performance may not be obtained.
On the other hand, patent document 3 proposes a method for producing a vitrified bonded grinding stone having a high porosity of 50 to 98 volume%, in which abrasive grains, a vitrified bond, a curing agent (gelling agent), water, and a surfactant are mixed instead of a pore forming agent to obtain a cake-like foamed material, the foamed material is cooled in a forming mold to produce a molded body, the dried molded body is fired, and the molded body is immersed in a liquid resin to coat a resin coating layer on a binder bridge which is an outer shell surrounding pores, thereby improving strength.
Prior art documents
Patent literature
Patent document 1: japanese patent laid-open publication No. 2006-001007
Patent document 2: japanese patent laid-open publication No. 2017-080847
Patent document 3: japanese patent laid-open No. 2007-290101
Disclosure of Invention
However, since the vitrified bonded grindstone obtained by the above-mentioned production method does not have independent pores, the deformation phenomenon of the bond bridges may progress and the molded body may shrink during the drying of the molded body molded from the cake-like foamed material, and it is difficult to produce a product having a stable shape.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a vitrified bonded grinding stone, which can stably produce a vitrified bonded grinding stone having a high porosity by communicating pores.
The present inventors have made various studies in view of the above circumstances, and as a result, have found that: the present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a vitrified bonded grinding stone, which can produce a vitrified bonded grinding stone having sufficient strength for grinding and high porosity by communicating pores, by obtaining a grinding stone raw material slurry obtained by mixing abrasive grains, a vitrified bond, and a water-soluble gelling agent, gelling the grinding stone raw material slurry in a forming mold to produce a formed body, freezing the formed body to produce a large number of frozen particles in the frozen formed body, sublimating the produced large number of frozen particles under vacuum to produce a formed body having pores communicating pores, and then firing the formed body. The present invention has been completed based on such findings.
That is, the gist of the present invention is to provide a method for producing a high-porosity vitrified bond grinding stone, (1) a method for producing a high-porosity vitrified bond grinding stone including a plurality of pores communicating with each other, the method including: (2) A grinding stone material preparation step of obtaining a grinding stone raw material slurry which is a mixed fluid in which a water-soluble polymer capable of gelling, abrasive grains, a ceramic binder and water are dissolved; (3) A molding step of obtaining a molded body by gelling the grindstone raw material slurry using a molding die; (4) A freeze vacuum drying step of freezing the molded body after the molding step to generate a plurality of frozen particles in the molded body, and drying the molded body by sublimating the frozen particles by placing the molded body in which the frozen particles are generated under vacuum; and (5) a firing step of firing the compact after the freeze-vacuum drying step to bond the abrasive grains with the ceramic bond, thereby obtaining the high-porosity ceramic bond grindstone.
According to the method for producing a high-porosity vitrified bond grinding stone of the present invention, the frozen vacuum drying step is adopted, and the formed body in which a plurality of frozen particles are formed is placed under vacuum, whereby the frozen particles in the formed body are sublimated and dried, and a plurality of pores communicating with each other are formed after the frozen particles are sublimated. Therefore, since the shrinkage of the molded body is suppressed, a vitrified bond grinding stone having a high porosity realized by a plurality of interconnected pores can be stably produced.
In the vacuum freeze drying step, the pores are preferably formed in a place where the frozen particles in the grinding stone raw material slurry once exist after the frozen particles are sublimated. The pores thus formed do not disappear, and shrinkage of the molded article thus molded is suppressed.
In the freeze-vacuum drying step, it is preferable that the frozen particles are generated in the gel-like raw material slurry for a grinding stone constituting the molded body, the abrasive grains and the ceramic bond are aggregated in a matrix portion surrounding the frozen particles, and in the firing step, a binder bridge which is a shell surrounding the pores is formed by the matrix portion by firing of the matrix portion. Thus, the strength of the binder bridge is improved without applying a reinforcing resin coating layer, and the ceramic binder grinding stone can be ground even if it has a high porosity.
Further, the high-porosity vitrified bond grindstone preferably has a pore volume ratio of 65 to 90 vol%. Since the high-porosity vitrified bond grinding wheel is configured to have a pore volume ratio of 65 vol% to 90 vol%, grinding efficiency and grinding wheel strength can be obtained at the same time.
Preferably, the high-porosity vitrified bond grinding stone has a specific gravity of 0.34 to 1.48. Thus, a relatively light high-porosity vitrified bond grinding stone having a specific gravity of 0.34 to 1.48 can be obtained.
Further, it is preferable that the abrasive grains have a center particle diameter (median diameter) smaller than the thickness of the bond bridge constituting the outer shell of the air hole. Therefore, since the abrasive grains are significantly smaller than the thickness of the binder bridge corresponding to the outer shell of the pores, the binder bridge locally becomes a pore-free vitrified bond grinding stone structure and the strength is improved, and therefore, the grinding performance of the high-porosity vitrified bond grinding stone is improved and the surface roughness suitable for grinding the semiconductor wafer can be obtained.
Drawings
Fig. 1 is a view illustrating a cup-shaped grinding stone in which a high-porosity vitrified bond grinding stone manufactured by a method for manufacturing a high-porosity vitrified bond grinding stone according to an embodiment of the present invention is fixed to a base member.
Fig. 2 is a process diagram illustrating a main part of the method for producing the high-porosity vitrified bond grinding stone shown in fig. 1.
Fig. 3 is a view schematically showing a structural change in the molded body of the high-porosity vitrified bond grinding stone in the manufacturing process shown in fig. 2, (a) is a view showing a state in which a grinding stone raw material slurry is prepared in the grinding stone material preparation process, (b) is a view showing a state in which frozen particles are generated in the molded body by freezing in the freeze vacuum drying process, (c) is a view showing a state in which the frozen particles are sublimated in the molded body by vacuum drying in the freeze vacuum drying process, and (d) is a view showing a state in which the molded body is fired in the firing process.
Fig. 4 is a diagram showing a round sample (formed body) on the left side in the case where the same drying as in the freeze-vacuum drying step of fig. 2 is performed, and showing a round sample (formed body) on the right side in the case where the normal pressure drying is performed.
Fig. 5 is a view showing an optical microscope photograph on the left side, which shows an enlarged view of the pore structure of the molded article before the firing step of fig. 2, and an optical microscope photograph on the right side, which shows an enlarged view of the pore structure of the molded article after the firing step.
Fig. 6 is an SEM photograph showing an enlarged pore structure of the compact after the firing step of fig. 2.
Fig. 7 is an SEM photograph showing a further enlarged pore structure of the compact after the firing step of fig. 2.
Fig. 8 is a graph showing the main portions of the grinding stone structures and grinding ratios of samples 1 to 10 produced by the same steps as those shown in fig. 2 and samples 11 to 12 for comparison.
Fig. 9 is a diagram showing samples 1 to 12 of fig. 8 in two-dimensional coordinates of a horizontal axis indicating Vg/Vb and a vertical axis indicating specific gravity ρ.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the drawings are simplified or modified as appropriate, and the dimensional ratios, shapes, and the like of the respective portions are not necessarily drawn accurately.
Examples
Fig. 1 is a perspective view showing a cup-shaped grindstone 14 in which a plurality of segment grindstones 10, which are an example of a high-porosity vitrified bond grindstone according to an embodiment of the present invention, are fixed in a continuous annular shape along an outer peripheral edge of a lower surface of a metallic, for example, aluminum, disk-shaped base member 12. The segment grinding stones 10 each have a grinding surface 16 formed in an annular shape and connected to the outer peripheral portion of the lower surface of the base member 12.
The base member 12 is in the form of a thick circular plate made of metal, and is attached to a spindle of a grinding apparatus not shown, whereby the cup-shaped grinding stone 14 is rotationally driven. The cup-shaped grindstone 14 has, for example, an outer diameter of about 250mm, and the segment grindstone 10 has, for example, a width dimension of about 3mm and a thickness dimension of about 5 mm. The segmented grinding stone 10 performs machining of the thickness of a workpiece by bringing a grinding surface 16 into sliding contact with the workpiece, for example, a silicon wafer, with rotation of the base member 12, and grinding or polishing the workpiece into a flat shape.
The segmented grinding stone 10 is manufactured by, for example, a manufacturing process shown in fig. 2. In the grinding stone material preparation process P1, a grinding stone raw material slurry 18 of the segment grinding stone 10 is prepared. The grinding stone raw material slurry 18 is prepared so as to have fluidity by blending superabrasive grains (super abrasive grains), for example, 17 mass% of diamond abrasive grains 20, 15 mass% of ceramic bond 22, 3 mass% of water-soluble polysaccharide gelling agent 24 functioning as a primary binder, and 65 mass% of water 26 functioning as a pore forming agent, and heating at a temperature of, for example, 90 ℃ or higher to dissolve the water-soluble polysaccharide gelling agent 24 in the water 26. The water-soluble polysaccharide gelling agent 24 corresponds to the water-soluble polymer capable of gelling of the present invention.
Fig. 3 (a) schematically shows the grindstone raw material slurry 18. The water-soluble polysaccharide gelling agent 24 dissolved in the water 26 is a fibrous polysaccharide molecule in fig. 3 (a), and is schematically shown. The polysaccharide molecules (water-soluble polysaccharide gelling agents 24) are entangled with each other and adhered to each other to form a mesh structure, thereby forming many minute spaces for accommodating the water 26. Further, the entanglement of the polysaccharide molecules (the water-soluble polysaccharide gelling agent 24) causes the gel to lose fluidity when the temperature is lowered from the heating temperature. As the water-soluble polysaccharide gelling agent 24, for example, curdlan, tamarind gum, xanthan gum (kitan sangg gum) + locust bean gum, sodium alginate, gellan gum (gelangum), pectin, carrageenan, gelatin, agar and the like can be used.
The composition of the vitrified bond 22 is, for example: siO 2 2 50 to 54 wt.% of Al 2 O 3 13 to 15 wt.% of B 2 O 3 Is not less than 17.5 wt% and20.5 wt% or less, RO (RO is at least 1 oxide selected from CaO, mgO, baO, and ZnO) of 0.7 wt% or more and 6.5 wt% or less, and R 2 O(R 2 O is selected from Li 2 O、Na 2 O、K 2 1 or more oxides among O) of 0.0 to 9.0 wt%, P 2 O 5 Is 0.7 to 1.3 wt%.
In the next molding step P2, the fluidized grindstone raw material slurry 18 in a heated state is poured into a molding cavity provided in a molding die in a predetermined shape, for example, a shape slightly larger than the segmented grindstone 10, and the temperature is lowered to a temperature lower than the dissolution temperature of the water-soluble polysaccharide gelling agent 24, for example, normal temperature, whereby a molded body 28 is obtained, which is obtained by gelling, i.e., curing, the fluidized grindstone raw material slurry 18, and is taken out from the molding die. Fig. 3 (a) shows a state after gelation.
Next, in the freeze vacuum drying step P3, the molded body 28 is placed in the chamber of the freeze vacuum dryer. As a result, the formed body 28 is frozen at a predetermined freezing temperature of, for example, minus 15 ℃, a plurality of frozen particles 30 of a predetermined size are precipitated from the water 26 in the formed body 28, and the frozen particles 30 are grown to a predetermined size by maintaining the freezing for a predetermined freezing time. Fig. 3 (b) schematically shows this state. In this frozen state, the particles of the diamond abrasive grains 20 and the ceramic bond 22 are driven to the interface of the frozen particles 30. That is, the diamond abrasive grains 20 and the ceramic bond 22 are gathered in the matrix portion 34 surrounding the frozen particles 30.
Next, in the freeze vacuum drying step P3, the plurality of frozen particles 30 in the molded body 28 are vacuum-dried at, for example, 35 ℃ so as to gradually sublimate by being brought into a vacuum state for a predetermined time period at a predetermined vacuum value lower than 610Pa, for example, 10Pa, and thereby a plurality of pores 32 are formed in the portion where the plurality of frozen particles 30 were once located. Fig. 3 (c) schematically shows this state. In this state, the diamond abrasive grains 20 and the ceramic bond 22 are dispersed so as to be incorporated into the fibrous polysaccharide molecules (water-soluble polysaccharide gelling agent 24) surrounding the pores 32. Since many of the frozen particles 30 in the formed body 28 contact each other during growth, many of the pores 32 formed by sublimation of the frozen particles 30 are communicated pores.
Fig. 4 is a photograph showing on the left side a compact molded into a circular sample, which has undergone the same steps until frozen particles grow to a predetermined size by freezing at the above-described preset freezing temperature and freezing time, a compact dried in a vacuum in a frozen state, and a compact dried at 50 ℃ under atmospheric pressure using the compact on the right side. The molded article after freeze-vacuum drying shown on the left side of fig. 4 had a strength enough to be easily held by hand without being crushed in shape. On the other hand, the molded body after the atmospheric drying shown on the right side of fig. 4 had a large shape collapse, and the production of the high-porosity vitrified bond grinding stone was not achieved.
In the firing step P4, the molded body 28 having the plurality of pores 32 formed therein is fired at a firing temperature set to be equal to or higher than the softening temperature of the ceramic binder 22, for example, a firing temperature of 500 to 1000 ℃. As a result, the fibrous polysaccharide molecules (water-soluble polysaccharide gelling agent 24) surrounding the pores 32 are burned off (burned off), and the diamond abrasive grains 20 and the ceramic bond 22 are sintered to form bond bridges 36 surrounding the pores 32. Thereby, the segment grinding stone 10 as a high porosity vitrified bond grinding stone was obtained. Fig. 3 (d) schematically shows this state.
The bond bridge 36 has a thickness of, for example, about 10 μm, and holds the diamond abrasive grains 20 having a center particle diameter of several μm smaller than the thickness, and therefore, is configured to have a dense structure such as a pore-free ceramic bond grinding stone without pores, and the strength of the bond bridge 36 is improved without applying a resin coating layer for reinforcement. Here, the center particle diameter of the diamond abrasive grains 20 is a median diameter (median particle diameter) specified by japanese industrial standards (JIS Z8825: 2013), and is a value based on a volume-converted D50.
Fig. 5 shows an optical microscope photograph on the left side, which shows an enlarged view of the pore structure of the compact 28 before the firing step P4, and an optical microscope photograph on the right side, which shows an enlarged view of the pore structure of the high-porosity ceramic binder grindstone 10 as the compact 28 after the firing step P4. As is apparent from fig. 5, in the pore structure of the molded body 28 after the firing step P4, no change due to the firing step P4 is observed, and the pore structure before the firing step P4 is maintained.
Fig. 6 is an SEM photograph showing a further enlarged pore structure of the compact 28 (i.e., the high-porosity vitrified bond grinding stone 10) after the firing step P4. The white lines in fig. 6 indicate the bond bridges 36 surrounding the pores 32. Fig. 7 is an SEM photograph showing the binder bridge 36 at a further enlarged scale. As shown in fig. 7, the bond bridge 36 is a dense structure. The fine particles on the bond bridge 36 are diamond abrasive particles 20. The center particle diameter of the diamond abrasive grains 20 is not less than 1/50 of the thickness of the bond bridge 36 and not more than the same thickness.
Returning to fig. 2, in the joining/working step P5, the plurality of segmented grinding stones 10 fired in the firing step P4 are joined to the base member 12 as shown in fig. 1. Then, the segment grinding stone 10 bonded to the base member 12 is processed using a dresser.
Hereinafter, values (= Vg/Vb), specific gravity ρ, pore volume fraction Vp (volume%), and grinding ratio GR of the center particle diameter of the diamond abrasive grain, the ratio of the volume fraction Vg (volume%) of the diamond abrasive grain to the volume fraction Vb (volume%) of the ceramic bond, of samples 1 to 10 (examples), which were the ceramic bond grindstones (40 mm × 3mm × 5 mm) in a sheet shape (chip-shaped) produced by the present inventors by changing the proportions of the diamond abrasive grain, the ceramic bond, the water-soluble polysaccharide gelling agent, and water in the same process as that shown in fig. 2, are shown in fig. 8. Further, fig. 8 shows samples 11 to 12 (comparative examples) which are plate-shaped ceramic bond grindstones (40 mm × 3mm × 5 mm) produced by the conventional step of forming pores using a pore-forming agent, in the same manner as in samples 1 to 10. Fig. 9 is a diagram in which points representing the samples 1 to 12 in fig. 8 are plotted on two-dimensional coordinates of a horizontal axis representing Vg/Vb and a vertical axis representing specific gravity ρ. Here, the specific gravity ρ of the grinding stone is a value obtained by dividing the mass of the grinding stone by the volume of the grinding stone determined from the size of the grinding stone. The volume ratio Vg of the abrasive grains is a value obtained by dividing the abrasive grain volume obtained by dividing the mass of the abrasive grains by the specific gravity of the abrasive grains by the grinding stone volume. The volume ratio Vb of the binder is a value obtained by dividing the volume of the binder obtained by dividing the mass of the binder by the specific gravity of the binder by the volume of the grinding stone. The pore volume ratio Vp is a value obtained by dividing the volume of pores by the volume of the grinding stone.
As shown in fig. 8 and 9, particularly with respect to the pore volume ratio Vp and the grinding ratio GR, there are clear differences between the samples 1 to 10 and the samples 11 to 12. The pore volume ratio Vp of samples 1 to 10 is 65 vol% to 90 vol%, and therefore, is larger than that of samples 11 to 12, and the grinding ratio GR is 11 to 750, and therefore, is remarkably larger than that of samples 11 to 12.
The grinding test 1 using a grinding stone of sample 9 (example product) and sample 11 (comparative example product) and the grinding test 2 using a grinding stone of sample 3 (example product) and sample 12 (comparative example product) will be described below in detail. Grinding test 2 is a grinding test in which rough machining is assumed, and grinding test 1 is a grinding test in which finish machining is assumed.
(grinding test 1)
Composition of ceramic Binder
Comprising SiO 2 :51.5 mass% of Al 2 O 3 : 14.7% by mass, B 2 O 3 : 18.9% by mass of Na 2 O: 3.9% by mass, K 2 O:3.8 mass%, mgO:2.0 mass%, caO:1.9 mass%, baO: 0.7% by mass, P 2 O 5 : 0.9% by mass.
Blending of sample 9
Diamond abrasive grains having a center particle diameter of 0.2 μm: 17% by mass
Ceramic bond: 15% by mass
Water-soluble polysaccharide gelling agent (agar): 3% by mass
Water: 65% by mass
Method for producing sample 9
From the blending described above, through the manufacturing process shown in fig. 2, diamond abrasive grains having a volume ratio Vg of 7.0 vol%, a volume ratio Vb of the vitrified bond of 8.6 vol%, vg/Vb =0.8, a pore volume ratio Vp of 84.4 vol%, and a specific gravity of 0.46g/cm were prepared 3 The vitrified bonded grinding stone (sample 9) having the same shape as the segmented grinding stone 10, i.e., a plate shape.
Method for producing sample 11
The conventional process of forming pores using the pore former produced diamond abrasive grains having a center particle diameter of 0.2 μm and a volume ratio Vg of 27.2 vol%, the volume ratio Vb of the ceramic bond similar to that of sample 9 was 17.3 vol%, vg/Vb =1.6, the pore volume ratio Vp was 55.5 vol%, and the specific gravity was 1.55g/cm 3 The vitrified bond grinding stone having such a structure has the same shape as the segment grinding stone 10, i.e., a plate shape (sample 11).
Grinding test method
The grinding wheels obtained by bonding the vitrified bonded grinding stones of samples 9 and 11 to the lower surface of an aluminum base member having an outer diameter of 300mm as shown in fig. 1 were mounted on a vertical-axis surface grinding machine, and were carried out under the following grinding conditions for a silicon wafer having a diameter of 12 inches.
Machining conditions of grinding test
Grinding the stone at a rotating speed: 3000rpm
Stage (wafer) rotation speed: 395rpm
Axial feeding speed of grindstone: 0.5 μm/sec
Wafer processing allowance: thickness of 20 μm
Grinding test results of sample 9
Abrasion amount of grindstone of sample 9: 1.7 μm
Machining current value: 19.0A
Surface roughness Ra (JIS B0601: 1.2nm
Results of grinding test on sample 11
Grindstone wear amount of sample 11: 35.3 μm
Machining current value: 18.9A
Surface roughness Ra (JIS B0601: 1.2nm
Evaluation of grinding test results
The grinding using sample 9 did not have a large difference in the machining current value and the surface roughness Ra compared to the grinding using sample 11 obtained by the conventional manufacturing method. However, since the grinding ratio when sample 9 was used was 11.8 (= 20 μm/1.7 μm) and the grinding ratio when sample 11 was used was 0.57 (= 20 μm/35.3 μm), the amount of wear of the grinding stone when sample 9 was used was significantly reduced.
(grinding test 2)
Composition of the ceramic Binder
Comprising SiO 2 : 51.5% by mass of Al 2 O 3 :14.7 mass% of B 2 O 3 : 18.9% by mass of Na 2 O: 3.9% by mass, K 2 O:3.8 mass%, mgO:2.0 mass%, caO:1.9 mass%, baO: 0.7% by mass, P 2 O 5 : 0.9% by mass.
Preparation of sample 3
Diamond abrasive grains having a center particle diameter of 6 μm: 21 mass%
Ceramic bond: 12% by mass
Water-soluble polysaccharide gelling agent (agar): 3% by mass
Water: 64% by mass
Method for producing sample 3
From the blending, the manufacturing process shown in fig. 2 produced diamond abrasive grains having a volume ratio Vg of 17.3 vol%, a volume ratio Vb of the ceramic bond of 14.2 vol%, vg/Vb =1.2, a pore volume ratio Vp of 68.5 vol%, and a specific gravity of 0.96g/cm 3 The ceramic bond grindstone having the same shape as the segment grindstone 10, i.e., a plate shape, was structured in this manner (sample 3).
Method for producing sample 12
Through the conventional step of forming pores using a pore former, diamond abrasive grains having a center particle diameter of 6 μm were produced with a volume ratio Vg of 40.9 vol%, a volume ratio Vb of 12.3 vol%, vg/Vb =3.3, a pore volume ratio Vp of 47.8 vol%, and the same vitrified bond as in sample 3,Specific gravity of 1.95g/cm 3 The vitrified bond grinding stone having such a structure has the same shape as the segmented grinding stone 10, i.e., a plate shape (sample 12).
Grinding test method
The grinding wheels obtained by bonding the vitrified bonded grinding stones of samples 3 and 12 to the lower surface of an aluminum base member having an outer diameter of 300mm as shown in fig. 1 were mounted on a vertical-axis surface grinding machine, and were carried out under the following grinding conditions for a silicon wafer having a diameter of 12 inches.
Machining conditions of grinding test
Grinding the stone at a rotating speed: 2000rpm
Stage (wafer) rotation speed: 300rpm
Axial feeding speed of grinding stone: 4.0 μm/sec
Wafer processing allowance: thickness of 150 μm
Grinding results of sample 3
Grindstone abrasion amount of sample 3: 0.2 μm
Machining current value: 23.8A
Surface roughness Ra (JIS B0601: 44.4nm
Grinding results of sample 12
Grindstone wear amount of sample 12: 164 μm
Machining current value: 14.2A
Surface roughness Ra (JIS B0601: 39.1nm
Evaluation of grinding test results
The grinding using sample 3 has a higher machining current value than the grinding using sample 12 obtained by the conventional manufacturing method, but has no large difference in surface roughness Ra. However, since the grinding ratio in the case of using sample 3 was 750 (= 150 μm/0.2 μm) and the grinding ratio in the case of using sample 12 was 0.91 (= 150 μm/164 μm), the amount of wear of the grinding stone in the case of using sample 3 was significantly reduced.
As described above, the method for producing the high-porosity vitrified bond grinding stone 10 (segment grinding stone 10) according to the present embodiment is a method for producing a high-porosity vitrified bond grinding stone 10 including a plurality of pores 32 communicating with each other, and includes: a grinding stone material preparation step P1 of obtaining a grinding stone raw material slurry 18, the grinding stone raw material slurry 18 being a mixed fluid of diamond abrasive grains (abrasive grains) 20, a ceramic bond 22, and water 26 in which a water-soluble polysaccharide gelling agent 24 is dissolved; a molding step P2 of obtaining a molded body 28 by gelling the grindstone raw material slurry 18 using a molding die; a freeze vacuum drying step P3 of freezing the molded body 28 after the molding step P2 to generate a plurality of frozen particles 30 inside the molded body 28, and drying the molded body 28 by sublimating the frozen particles 30 inside the molded body 28 by placing the molded body 28 in which the frozen particles 30 are generated in a vacuum; and a firing step P4 of firing the compact 28 after the freeze-vacuum drying step P3 to bond the diamond abrasive grains 20 to each other with the ceramic bond 22, thereby obtaining the high-porosity ceramic bond grinding stone 10. In this way, in the freeze vacuum drying step P3, the formed body 28 in which the plurality of frozen particles 30 are generated is placed under vacuum, whereby the frozen particles 30 in the formed body 28 are sublimated and dried, and the frozen particles 30 are sublimated to form the air holes 32 communicating with each other. Therefore, since the compact 28 is not shrunk by the disappearance of the bubbles, the high-porosity vitrified bond grinding stone 10 in which the high porosity is realized by the communicating pores 32 can be stably manufactured.
In the method of manufacturing the high-porosity vitrified grinding stone 10 according to the present embodiment, the plurality of interconnected pores 32 are formed in the place where the frozen particles 30 were once present in the molded body 28 after the plurality of frozen particles 30 are sublimated in the freeze vacuum drying step P3. The air holes 32 thus formed do not disappear, and the shrinkage of the molded body 28 is suppressed.
In the method for manufacturing the high-porosity ceramic bond grinding stone 10 according to the present embodiment, in the freeze vacuum drying step P3, the frozen particles 30 are generated in the formed body 28 in which the grinding stone raw material slurry 18 is solidified into a gel, the diamond abrasive grains 20 and the ceramic bond 22 are gathered in the matrix portion 34 surrounding the frozen particles 30, and in the firing step P4, the binder bridge 36 which is an outer shell surrounding the pores 32 is formed by firing the matrix portion 34, whereby the binder bridge 36 is configured into a pore-free grinding stone having no pores. As a result, the strength of the binder bridge 36 is improved without applying a reinforcing resin coating layer, and the high-porosity vitrified bond grinding stone 10 can be ground even if it has high porosity.
In the method for producing the high-porosity vitrified bond grinding stone 10 according to the embodiment, the pore volume ratio Vp of the high-porosity vitrified bond grinding stone 10 is 65 vol% to 90 vol%. In this way, the high-porosity vitrified bond grinding wheel 10 has a pore volume fraction Vp of 65 vol% to 90 vol%, and therefore can achieve both grinding efficiency and grinding wheel strength.
In the method for producing the high-porosity vitrified grinding stone 10 according to the embodiment, the specific gravity of the high-porosity vitrified grinding stone 10 is 0.34 to 1.48. Thus, a relatively light high-porosity vitrified bond grinding stone 10 having a specific gravity of 0.34 to 1.48 can be obtained.
In the method for manufacturing the high-porosity vitrified grinding stone 10 according to the embodiment, the grinding ratio of the high-porosity vitrified grinding stone 10 is 11 to 750. Since the grinding ratio is as high as 11 to 750, the high-porosity vitrified bond grinding stone 10 having durability can be obtained.
In addition, according to the method for manufacturing the high-porosity ceramic bond grinding stone 10 of the present embodiment, the center particle diameter of the diamond abrasive grains 20 is smaller than the thickness of the bond bridge 36 forming the outer shell of the plurality of pores 32. Since the diamond abrasive grains 20 are significantly smaller than the thickness of the bond bridges 36 corresponding to the outer shells of the pores 32, the bond bridges 36 locally form a pore-free vitrified bond grinding stone structure and have improved strength, and therefore, the grinding performance of the high-porosity vitrified bond grinding stone 10 is improved, and surface roughness suitable for grinding a semiconductor wafer can be obtained.
In addition, according to the method for manufacturing the high-porosity vitrified bond grinding stone 10 of the present embodiment, the vitrified bond 22 includes the following substances: siO 2 2 50 to 54 wt%, al 2 O 3 13 to 15% by weight, B 2 O 3 17.5 to 20.5 wt%, where RO is at least one oxide selected from CaO, mgO, baO and ZnOWhen R is equal to or greater than 0.7 wt% to 6.5 wt%, the amount of RO is preferably 0.7 wt% to 6.5 wt% 2 O is set to be selected from Li 2 O、Na 2 O、K 2 At least 1 oxide of O, R is 2 0.0 to 9.0 wt.% of O, P 2 O 5 0.7 to 1.3 wt%. This can provide the high-strength vitrified bond 22 suitable for grinding a semiconductor wafer, and improve the durability of the high-porosity vitrified bond grinding stone 10.
Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention is not limited to this embodiment and may be implemented in other ways.
For example, in the above-described embodiment, the arcuate segment grinding stone 10 fixed to the base member 12 is described as the high-porosity ceramic bond grinding stone, but the high-porosity ceramic bond grinding stone may be formed into a disk shape or a grinding stone having another shape.
In addition, in the segmented grinding stone 10, it is also possible to: the grinding stone layer formed at a portion involved in grinding, for example, a portion on the grinding surface 16 side is a high-porosity vitrified bond grinding stone.
In the above-described embodiment, the diamond abrasive grains are used as the abrasive grains, but the abrasive grains may not be the diamond abrasive grains, and abrasive grains other than the superabrasive grains may be used. In the above examples, the water-soluble polysaccharide gelling agent was used, but the water-soluble polymer may be a water-soluble polymer that can be gelled instead of the polysaccharide.
The above description is merely an embodiment, and is not intended to exemplify the invention, but the invention may be implemented in various forms by making various changes and improvements based on knowledge of those skilled in the art without departing from the gist thereof.
Description of the reference numerals
10: segmental grindstone (high-porosity vitrified bond grindstone), 12: base member, 14: cup-shaped grindstone, 16: ground surface, 18: grindstone raw material slurry, 20: diamond abrasive grains (abrasive grains), 22: ceramic bond, 24: water-soluble polysaccharide gelling agent (water-soluble polymer capable of gelling), 26: water, 28: formed body, 30: frozen particles, 32: air hole, 34: matrix portion, 36: a binder bridge.
Claims (6)
1. A method for producing a high-porosity vitrified bond grinding stone comprising a plurality of interconnected pores, the method comprising:
a grinding stone material preparation step of obtaining a grinding stone raw material slurry which is a mixed fluid in which a water-soluble polymer capable of gelling, abrasive grains, a ceramic binder and water are dissolved;
a molding step of obtaining a molded body by gelling the grindstone raw material slurry using a molding die;
a freeze vacuum drying step of freezing the molded body after the molding step to generate a plurality of frozen particles in the molded body, and drying the molded body by sublimating the frozen particles by placing the molded body in which the frozen particles are generated under vacuum; and
and a firing step of firing the compact after the freeze-vacuum drying step to bond the abrasive grains with the ceramic binder, thereby obtaining the high-porosity ceramic binder grinding stone.
2. The method of manufacturing a high-porosity vitrified grinding stone according to claim 1, wherein the pores are formed in a place where the frozen particles once exist in the grinding stone raw material slurry after the frozen particles are sublimated in the freeze vacuum drying step.
3. The method of manufacturing a high-porosity vitrified bond grinding stone according to claim 1 or 2, wherein the frozen particles are generated in the gelatinous grinding stone raw material slurry constituting the compact in the freeze vacuum drying step, the abrasive grains and the vitrified bond are gathered in a matrix portion surrounding the frozen particles, and a binder bridge which is a shell surrounding the pores is formed by the matrix portion by firing of the matrix portion in the firing step.
4. The method for producing a high-porosity vitrified bond grinding stone according to any one of claims 1 to 3, wherein the pore volume ratio of the high-porosity vitrified bond grinding stone is 65 to 90 vol%.
5. The method for producing a high-porosity vitrified bond grinding stone according to any one of claims 1 to 4, wherein the specific gravity of the high-porosity vitrified bond grinding stone is 0.34 to 1.48.
6. The method according to claim 3, wherein the abrasive grains have a center particle diameter smaller than the thickness of the bond bridge constituting the outer shell of the pores.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2020-061571 | 2020-03-30 | ||
| JP2020061571A JP6737975B1 (en) | 2020-03-30 | 2020-03-30 | Method for manufacturing high porosity vitrified grinding wheel |
| PCT/JP2020/046424 WO2021199509A1 (en) | 2020-03-30 | 2020-12-11 | Method for producing high-porosity vitrified grinding stone |
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| CN115397616A true CN115397616A (en) | 2022-11-25 |
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| CN202080099424.1A Pending CN115397616A (en) | 2020-03-30 | 2020-12-11 | Method for manufacturing high-porosity ceramic bond grindstone |
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| US (1) | US20230150094A1 (en) |
| JP (1) | JP6737975B1 (en) |
| KR (1) | KR20220158746A (en) |
| CN (1) | CN115397616A (en) |
| WO (1) | WO2021199509A1 (en) |
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| JP2022096834A (en) * | 2020-12-18 | 2022-06-30 | 株式会社ディスコ | Grinding wheel |
| CN115519484A (en) * | 2022-09-27 | 2022-12-27 | 郑州磨料磨具磨削研究所有限公司 | High-porosity ceramic bond diamond grinding wheel and preparation method thereof |
| CN116751073B (en) * | 2023-08-23 | 2023-10-24 | 天津南极星隔热材料有限公司 | Preparation method of lightweight heat-insulating aluminum borate porous ceramic with multistage pore structure |
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| JPH06503062A (en) * | 1990-12-04 | 1994-04-07 | ユナイテッド テクノロジーズ コーポレイション | Composite integrated structure lapping machine and its manufacturing method |
| WO2004106001A1 (en) * | 2003-05-30 | 2004-12-09 | Bosch Corporation | Vitrified grinding wheel and method of manufacturing the same |
| JP4769488B2 (en) | 2004-05-20 | 2011-09-07 | 株式会社ディスコ | Vitrified bond grinding wheel manufacturing method |
| JP2007290101A (en) * | 2006-04-27 | 2007-11-08 | Disco Abrasive Syst Ltd | Vitrified bond grindstone and its manufacturing method |
| JP5955429B1 (en) * | 2015-03-06 | 2016-07-20 | トヨタ自動車北海道株式会社 | Continuously generating gear grinding method |
| CN104802104B (en) * | 2015-05-11 | 2019-01-08 | 中国矿业大学(北京) | A kind of preparation method of nano-grade ceramic binding agent extra hard material grinding wheel |
| JP6564686B2 (en) | 2015-10-28 | 2019-08-21 | 株式会社アライドマテリアル | Vitrified bond superabrasive wheel and wafer manufacturing method using the same |
| CN108314463B (en) * | 2018-04-10 | 2021-01-29 | 衢州学院 | Electrolytic copper filled porous diamond grinding tool and preparation method thereof |
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- 2020-03-30 JP JP2020061571A patent/JP6737975B1/en active Active
- 2020-12-11 CN CN202080099424.1A patent/CN115397616A/en active Pending
- 2020-12-11 US US17/916,354 patent/US20230150094A1/en active Pending
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| WO2021199509A1 (en) | 2021-10-07 |
| JP2021160006A (en) | 2021-10-11 |
| JP6737975B1 (en) | 2020-08-12 |
| KR20220158746A (en) | 2022-12-01 |
| US20230150094A1 (en) | 2023-05-18 |
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