CN104137181A - Method for manufacturing glass substrate for magnetic disk - Google Patents
Method for manufacturing glass substrate for magnetic disk Download PDFInfo
- Publication number
- CN104137181A CN104137181A CN201380009608.4A CN201380009608A CN104137181A CN 104137181 A CN104137181 A CN 104137181A CN 201380009608 A CN201380009608 A CN 201380009608A CN 104137181 A CN104137181 A CN 104137181A
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- Prior art keywords
- glass substrate
- grinding
- disc
- glass
- manufacture method
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Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
- B24B37/042—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor
- B24B37/044—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor characterised by the composition of the lapping agent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
- B24B37/07—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool
- B24B37/08—Lapping machines or devices; Accessories designed for working plane surfaces characterised by the movement of the work or lapping tool for double side lapping
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/14—Anti-slip materials; Abrasives
- C09K3/1409—Abrasive particles per se
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/14—Anti-slip materials; Abrasives
- C09K3/1436—Composite particles, e.g. coated particles
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/14—Anti-slip materials; Abrasives
- C09K3/1454—Abrasive powders, suspensions and pastes for polishing
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Composite Materials (AREA)
- Manufacturing Of Magnetic Record Carriers (AREA)
- Magnetic Record Carriers (AREA)
- Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
Abstract
This invention provides a method for manufacturing a glass substrate for a magnetic disk in which malfunctions such as head crashes and/or thermal asperities are less likely to occur when manufacturing a glass substrate for a magnetic disk by polishing the substrate using a zirconia abrasive as the polishing abrasive in a loose abrasive. A method for manufacturing a glass substrate for a magnetic disk having a polishing step in which, in a state where a donut-shaped glass substrate having at least a pair of main surfaces and two sidewall surfaces forming an inner hole and the contour of the glass substrate is held in a carrier, the pair of main surfaces are sandwiched by polishing pads attached to a turntable, and the glass substrate is polished due to the planetary gear motion of the carrier while a polishing solution is supplied to the pair of main surfaces, the manufacturing method being characterized in that the polishing solution contains, as the polishing abrasive, zirconia particles manufactured using a wet process.
Description
Technical field
The present invention relates to the manufacture method of glass substrate for disc.
Background technology
Nowadays, in personal computer or DVD (Digital Versatile Disc, digital versatile disc) pen recorder etc., be built-in with the hard disk unit (HDD:Hard Disk Drive, hard disk drive) for record data.In the hard disk unit particularly using in notebook personal computer etc. be take the equipment that movability is prerequisite, use is provided with magnetospheric disk on glass substrate, utilizes the magnetic head on the face that is slightly suspended in disk to record or read magnetic recording information to magnetosphere.As the substrate of this disk, owing to having than metal substrate (aluminium base) etc., be more difficult to occur the character of plastic yield, thereby preferably use glass substrate.
In addition, should increase the requirement of memory capacity in hard disk unit, seek the densification of magnetic recording.For example use perpendicular magnetic recording, making direction of magnetization in magnetosphere is vertical direction with respect to the face of substrate, carries out the miniaturization of magnetic recording information area (recorded bit (bit)).Thus, can increase 1 memory capacity in disc substrates.Further, in order further to increase memory capacity, also carry out by making the record-playback element portion of magnetic head more outstanding, thereby extremely shorten the distance between itself and magnetic recording layer, further improve recording of information playback accuracy (improving S/N ratio).It should be noted that, the control of the record-playback element portion of this magnetic head is known as DFH (Dynamic Flying Height, dynamic fly height) control gear, and the magnetic head that is equipped with this control gear is known as DFH head.For with the combination of this DFH head for for the substrate for magnetic disc of HDD, for fear of its with magnetic head or from magnetic head the collision between further outstanding record-playback element portion with contact, according to the mode that the concave-convex surface that makes substrate is minimum, make.
The operation of making glass substrate for disc comprises: grinding process, and the first type surface of making flat plate glass blank after utilizing bonded-abrasive to compression molding carries out grinding; The grinding step of first type surface, object is to remove because this grinding process is in the residual scar of first type surface, distortion.
In the past, a kind of known method, the method is used the various abrasive particles such as cerium oxide (ceria), silicon dioxide, zirconium dioxide (zirconia) as lapping compound in the grinding step of the first type surface of glass substrate for disc.For example, disclose a kind of method in patent documentation 1, the method is used the lapping liquid that has added calcium aluminate, magnesium sulfate, magnesium chloride etc. in zirconia abrasive particle to grind glass substrate for disc.
Prior art document
Patent documentation
Patent documentation 1: No. 2783329th, Jap.P.
Summary of the invention
The problem that invention will solve
But, thereby go out magnetosphere and make disk usining on the glass substrate that zirconia makes as the abrasive substance of the free abrasive of glass blanket film forming, utilization is slided head (Glide head) and has been carried out sliding inspection, result is compared with the glass substrate that uses existing cerium oxide to make as abrasive substance, has confirmed the reduction (being the rising of bad generation rate) of yield rate.Slide and check for judging whether magnetic head can stably maintain action with the specific suspension amount with respect to disk.Slide and check and to be undertaken by following manner: make to be installed on piezoelectric element etc. slide head on the first type surface of disk with the specifically amount of suspension flight, utilizing the detections such as piezoelectric element to slide head has collisionless with the thrusts such as foreign matter on disk first type surface, thereby slides inspection.
Therefore, the object of the present invention is to provide the manufacture method of glass substrate for disc, when grinding to manufacture glass substrate for disc as the abrasive substance of free abrasive with zirconia abrasive particle, can manufacture foreign matter and be difficult for remaining in the glass substrate for disc on glass substrate.
For the method for dealing with problems
The inventor, in order to verify the reduction reason that slides the yield rate of inspection based on above-mentioned, conducts in-depth research.It found that, for the first type surface of glass substrate, after bright finished grinding, even if fully clean first type surface, removes particle etc., but when carrying out magnetospheric film forming, sometimes at first type surface, is still attached with zirconia particles.Now, lamination magnetosphere and cause forming small protuberance on the surface of disk above zirconia particles.Thereby this small protuberance becomes the reason of the unfavorable conditions such as head crash fault, hot coarse fault.Further also known, the zirconia particles adhering at the first type surface of glass substrate is zirconia abrasive particle or its part of use in grinding, from the abrasive particle being attached on the outer peripheral face of glass substrate and the side wall surface of inner peripheral surface.It should be noted that, not yet set up the cleaning method of effectively removing the zirconia particles that is attached to glass substrate.
Even if fully clean first type surface, remove particle etc., while carrying out magnetospheric film forming, sometimes at first type surface, be still attached with zirconia particles, the inventor thinks that it be the reasons are as follows.; even in the situation that remaining zirconia particles by utilizing the first type surface of zirconia abrasive particle to grind on glass blanket; also can by after the final grinding of first type surface is removed to zirconia particles residual on first type surface, but on the side wall surface of glass blanket the residual or zirconia particles that adheres to can not by after the cleaning of glass blanket be removed.Especially in the situation that utilize the first type surface of zirconia abrasive particle to carry out in glass blanket being remained on to carrier in grinding, known due to glass blanket in grinding and carrier butt, thereby zirconia particles adheres to the side wall surface of glass blanket.And by inference,, in the operation after the first type surface that utilizes zirconia abrasive particle grinds, the zirconia particles adhering at side wall surface departs from and is attached to the first type surface of glass blanket or glass substrate for disc.For example can think, after the first type surface of glass blanket grinds, for the surface texture that makes first type surface variation not, the side wall surface of clamping glass blanket or glass substrate for disc in operation, but cause thus zirconia particles to depart from.In addition, can also think, while clamping the side wall surface of profile in the operation of glass substrate for disc being carried out to film forming, zirconia particles can depart from from side wall surface; And zirconia particles can depart from from the side wall surface of profile in the matting of glass substrate for disc.
In view of the foregoing, the inventor finds, by making in grinding step, as the zirconia particles that grinds abrasive particle use, be the shape being difficult at the side wall surface cementation of glass blanket, thereby adhere to the side wall surface of glass blanket and residual zirconia particles tails off, the situation that zirconia is attached to first type surface in rear operation thus reduces.Specifically, known: by making the primary particle of zirconia particles, be mellow and full shape, thereby zirconic particle to be difficult to adhere to the side wall surface of glass substrate.In addition, in order to make one of method that the primary particle of zirconia particles is mellow and full shape be conceived to utilize damp process to manufacture zirconia particles, thereby expect the technical scheme of the mode of following record.
, one of mode of the present invention relates to a kind of manufacture method of glass substrate for disc, it has following grinding step: by least having a pair of first type surface, remain in carrier with the glass substrate of the bagel type of 2 side wall surfaces of formation endoporus and profile, under this state, with the grinding pad of installing in grinding price fixing, clamp above-mentioned a pair of first type surface, to above-mentioned a pair of first type surface, supply with lapping liquid, utilize the planet wheel of above-mentioned carrier to move to grind above-mentioned glass substrate simultaneously, this manufacture method is characterised in that, above-mentioned lapping liquid contains and utilizes zirconia particles that damp process manufactures as grinding abrasive particle.
In the manufacture method of above-mentioned glass substrate for disc, preferred above-mentioned zirconia particles is that particle diameter is that primary particle set in the scope of 70nm～200nm forms.
In the manufacture method of above-mentioned glass substrate for disc, the BET specific surface area of preferred above-mentioned zirconia particles is in 4m
2/ g～15m
2in the scope of/g.
In the manufacture method of above-mentioned glass substrate for disc, in the scope of the mean grain size of preferred above-mentioned zirconia particles (D50) in 0.2 μ m～0.6 μ m.
In the manufacture method of above-mentioned glass substrate for disc, preferably, when the length of the major axis of the primary particle of above-mentioned zirconia particles being made as to X1, the length of the minor axis with major axis quadrature is made as to X2, X1/X2 is 1.0～1.3.
In the manufacture method of above-mentioned glass substrate for disc, the surfaceness of the end face of the above-mentioned carrier preferably contacting with the side wall surface of above-mentioned glass substrate is below 5 μ m.
In the manufacture method of above-mentioned glass substrate for disc, the surfaceness of the side wall surface of the glass substrate before the lapping liquid that preferred use has above-mentioned zirconia particles grinds is counted below 0.1 μ m with arithmetic average roughness Ra.
In the manufacture method of above-mentioned glass substrate for disc, the diameter of preferred above-mentioned glass substrate for disc is greater than 2.5 inches of sizes and thickness of slab is below 0.6mm.
The manufacture method of above-mentioned glass substrate for disc preferably has following chemical enhanced operation after above-mentioned grinding step: at the Fracture Toughness K of above-mentioned glass substrate
1cin the measurement that utilizes Vickers, be 0.7[MPa/m
1/2] under above treatment conditions, to above-mentioned glass substrate, carry out chemical enhanced.
Accompanying drawing explanation
Fig. 1 is the three-dimensional exploded view of the lapping device (double-side polishing apparatus) that uses in the first grinding step.
Fig. 2 is the sectional view of the lapping device (double-side polishing apparatus) that uses in the first grinding step.
Fig. 3 is the figure of the zirconia particles (second particle) of schematically illustrated embodiment.
Fig. 4 is for the figure of effect of the zirconia particles of embodiment is described.
Fig. 5 illustrates the figure of state that zirconia particles is pressed against the side wall surface of glass blanket, shows the situation of the zirconia particles that utilizes damp process manufacture and utilizes the situation of the zirconia particles that dry process manufactures.
The state of the schematically illustrated zirconia particles of Fig. 6 when playing a role in attrition process between the first type surface of glass blanket and grinding pad, shows situation (situation of this grinding step) and the situations of utilizing zirconia particles that dry process manufacture different from this grinding step of utilizing the zirconia particles that damp process manufactures.
Fig. 7 is the figure of assay method of particle diameter that the primary particle of zirconia particles is shown.
Embodiment
Below, the manufacture method of the glass substrate for disc of present embodiment is elaborated.
[glass substrate for disc]
As the material of the glass substrate for disc in present embodiment, can use alumina silicate glass, soda-lime glass, borosilicate glass etc.Especially from the viewpoint of can implement chemical enhanced and can make major surface flat degree and substrate excellent strength glass substrate for disc these, can preferably use alumina silicate glass.If unbodied alumina silicate glass further preferably.
Composition to the glass substrate for disc of present embodiment is not construed as limiting, but the glass substrate of present embodiment is preferably by the following unbodied alumina silicate glass forming that forms: be converted into oxide benchmark, with a % by mole expression, contain 50%～75% SiO
2; 1%～15% Al
2o
3; Add up to 5%～35% the Li that is selected from
2o, Na
2o and K
2at least a kind of composition in O; Add up to 0%～20% at least a kind of composition in MgO, CaO, SrO, BaO and ZnO that is selected from; And the ZrO that is selected from that adds up to 0%～10%
2, TiO
2, La
2o
3, Y
2o
3, Ta
2o
5, Nb
2o
5and HfO
2in at least a kind of composition.
Glass substrate for disc in present embodiment is circular glass sheet substrate.The size of glass substrate for disc is restriction not, for example, be preferably nominal diameter and be the glass substrate for disc of 2.5 inches.
[manufacture method of glass substrate for disc]
Below, the manufacture method about the glass substrate for disc of present embodiment, describes one by one to operation.But, also can suitably change the order of each operation.
(1) moulding of glass blanket and polishing operation
For example, in the molding procedure of glass blanket of utilizing float glass process, first, such as the melten glass of above-mentioned composition is flowed in the bath that is filled with the motlten metals such as tin continuously, obtain thus plate glass.Melten glass flows along direct of travel in the bath that applies tight temperature operation, and final formation is adjusted to desired thickness, the plate glass of width.From this plate glass, cut out the glass blanket of regulation shape, as the basis of glass substrate for disc.The surface of the molten tin in bath is level, and therefore, for the glass blanket obtaining by float glass process, its surperficial flatness is enough high.
In addition, for example, in the molding procedure of glass blanket of utilizing compression molding method, on the counterdie as gob material charging forming mould, supply with the glass gob being formed by melten glass, be used as the patrix of the gob shaping mould relative with counterdie, glass gob is carried out to compression molding.More particularly, on counterdie, supply with after the glass gob being formed by melten glass, make the lower surface of cylindrical mould for patrix (mo(u)ld top half trunk type) and the upper surface butt of cylindrical mould (counterdie trunk type) for counterdie, with the slipping plane between cylindrical mould and counterdie and counterdie, with the outside of the slipping plane between cylindrical mould, form the molding space of thin glass blanket exceeding patrix and patrix, and then fall patrix and carry out compression molding, carry out rising immediately patrix after compression molding.Thus, mold the basic glass blanket as glass substrate for disc.
It should be noted that, glass blanket is not limited to said method, can use drop-down (downdraw) method, draw the known manufacture methods such as (redraw) method, fusion method to manufacture again.
Then, two first type surfaces for the glass blanket that shape cuts out according to the rules, are used alumina series free abrasive to polish processing as required.Specifically, make to polish price fixing and push down the two-sided of glass blanket from upper and lower surface, on the first type surface of glass blanket, supply with the grinding fluid (slurry) that contains free abrasive, thereby they are relatively moved, polish processing.It should be noted that, while utilizing float glass process to carry out moulding to glass blanket, the precision of the roughness of the first type surface after moulding is high, therefore also can omit this polishing processing.
(2) bore core operation
Use diamond head cylindraceous, at the central part formation endoporus of glass blanket, make circular glass blanket.
(3) chamfering process
After boring core operation, carry out chamfering process, in end, (peripheral end and interior all ends) forms chamfered section.In chamfering process, for peripheral end and interior all ends of circular glass blanket, such as by using the enforcement chamferings such as metal bonded wheel (メ タ Le ボ Application De whetslate) of diamond abrasive grain, form chamfered section.
(4) end surface grinding operation
Then, carry out the end surface grinding (edge polishing) of circular glass blanket.
In end surface grinding, utilize scratch brushing (brushing) to grind the side wall surface (end face) of the side wall surface of the inner circumferential side of glass blanket (end face) and outer circumferential side is carried out to mirror polish.Now, use and contain the particulates such as cerium oxide as the slurry of free abrasive.By carrying out end surface grinding, remove the damage at pollution, breakage or the scar etc. of the side wall surface adhesive dust of glass blanket etc., can prevent thus generation that heat is coarse, prevent that the ion that causes corrosion of sodium, potassium etc. separates out.
Thereby in order to make the end face of glass blanket smoothly make in the first grinding step of rear operation zirconia abrasive particle be difficult to be attached to the side wall surface of glass blanket, end surface grinding operation was preferably carried out before the first grinding step.For example, preferably carrying out end surface grinding, to make the arithmetic average roughness Ra of the end face of the glass blanket after end surface grinding operation be below 0.1 μ m.
(5) utilize the grinding process of bonded-abrasive
Utilize in the grinding process of bonded-abrasive, use the double-sided grinding device that possesses planetary gears to carry out grinding to the first type surface of circular glass blanket.Double-sided grinding device has upper and lower a pair of price fixing (upper price fixing and lower price fixing), between upper price fixing and lower price fixing, clamps circular glass blanket.And, by the one of any of upper price fixing or lower price fixing or both are carried out to move operation, glass blanket and each price fixing are relatively moved, can carry out grinding to two of glass blanket first type surfaces thus.
(6) first grind (first type surface grinding) operation
Then, the first type surface of the glass blanket after grinding being implemented to first grinds.The first process redundancy grinding is for example several μ m～50 μ m left and right.
(6-1) lapping device
Lapping device for using in the first grinding step, sees figures.1.and.2 and describes.Fig. 1 is the three-dimensional exploded view of the lapping device (double-side polishing apparatus) that uses in the first grinding step.Fig. 2 is the sectional view of the lapping device (double-side polishing apparatus) that uses in the first grinding step.It should be noted that, in the grinding attachment that also goes for using in above-mentioned grinding process with the same formation of this lapping device.
As shown in Figure 1, lapping device has upper and lower a pair of price fixing, goes up price fixing 40 and lower price fixing 50.Between upper price fixing 40 and lower price fixing 50, clamp circular glass blanket G, by to the one of any of upper price fixing 40 or lower price fixing 50 or both are carried out to move operation, glass blanket G and each price fixing are relatively moved, can grind two first type surfaces of this glass blanket G thus.
See figures.1.and.2 the formation of lapping device is further specifically described.
In lapping device, do as a whole, on lower price fixing 50 and the bottom surface of upper price fixing 40 install the dull and stereotyped grinding pad 10 of toroidal.Carrier 30 has and is arranged on the tooth portion 31 of peripheral part and central gear 61 and annular wheel 62 engagements and for holding one or more hole portion 32 that keeps glass blanket G.The annular wheel 62 of central gear 61, its outer edges setting and discoideus carrier 30 are made the planetary gears of as a whole formation centered by central shaft CTR.Discoideus carrier 30 meshes in inner circumferential side and central gear 61, and in outer circumferential side and annular wheel 62 engagements, holds simultaneously and keep one or two above glass blanket G (workpiece).On lower price fixing 50, carrier 30 revolves round the sun when carrying out rotation as planet wheel, and glass blanket G and lower price fixing 50 are relatively moved.For example, if central gear 61 according to the CCW direction rotation of (counterclockwise), carrier 30 is according to the CW direction rotation of (clockwise), annular wheel 62 is according to the direction rotation of CCW.Its result makes to produce relative motion between grinding pad 10 and glass blanket G.Can similarly make glass blanket G and upper price fixing 40 relatively move.
In the action of above-mentioned relative motion, upper price fixing 40 is pressed towards glass blanket G (in vertical) with given load, and grinding pad 10 is pressed towards glass blanket G.In addition, by not shown pump, lapping liquid (slurry) is supplied between glass blanket G and grinding pad 10 via more than one or two pipe arrangement 72 from lapping liquid supplying tank 71.By the abrasive substance containing in this lapping liquid, the first type surface of glass blanket G is ground.Herein, the lapping liquid using in the grinding of preferred glass blanket G is discharged from from upper and lower price fixing, by not shown filtrator and backflow pipe arrangement and return to lapping liquid supplying tank 71 and be used again.
It should be noted that, in this lapping device, for the object of glass blanket G being set to desired grinding load, preferably adjust the load that upper price fixing 40 gives glass blanket G.From realizing the viewpoint of high grinding rate, load is preferably 50g/cm
270g/cm more preferably above,
290g/cm more preferably above,
2above.And from reducing the viewpoint of scraping and stay in grade, grind load and be preferably 180g/cm
2160g/cm more preferably below,
2140g/cm more preferably below,
2below.That is, load is preferably 50g/cm
2～180g/cm
2, 70g/cm more preferably
2～160g/cm
2, 90g/cm more preferably
2～140g/cm
2.
The feed speed of lapping liquid during attrition process because of the difference of the size of the composition of grinding pad 10, lapping liquid and concentration, glass blanket G different, but from improving the viewpoint of grinding rate, the feed speed of lapping liquid during attrition process is preferably 500ml/ minute～5000ml/ minute, more preferably 1000ml/ minute～4500ml/ minute, 1500ml/ minute～4000ml/ minute more preferably.The rotating speed of grinding pad 10 is preferably 10rpm～50rpm, more preferably 20rpm～40rpm, 25rpm～35rpm more preferably.
(6-2) grind abrasive particle (zirconia (ZrO
2))
(A) grind the method for refining of abrasive particle
The lapping liquid using in the lapping device of Fig. 1 contains the zirconia (ZrO that utilizes damp process (rather than dry process) to make
2) particle is as grinding abrasive particle.
Herein, the method that pulverized product that dry process refers to zirconia by being obtained by electric smelting method or the zirconic pulverized product of desiliconization, baddeleyite etc. is manufactured.It should be noted that, electric smelting method is zircon sand or baddeleyite etc. are heated to 2,700 ℃ of left and right and make silicon evaporation, thereby reduces silicon concentration, improve the technique of zirconium concentration.Desiliconization zirconia is to utilize electric smelting method to reduce the powder of silicon concentration.Baddeleyite is natural minerals, is the zirconia that silicon concentration is low when natural minerals, purity is higher.
On the other hand, damp process is different from dry process, is following method for making: generate the compound that contains zirconium is dissolved in to resulting solution in chemicals, carry out crystal growth in this solution, generate the colloidal sol that contains zirconium etc., and fire and manufacture zirconium.For example, in known damp process, roughly pass through following operation (I)～(V) and generate zirconic powder.
(I) beneficiating process of floating: for zirconium ore, by having utilized the ratio gravity ore of the difference of proportion to remove silica sand, and then utilize poor, the magnetic of proportion, electric conductivity to screen ilmenite, rutile, monazite, make Zircon Concentrate (zircon sand).
(II) NaOH melting operation: utilize NaOH melting zircon sand and separated silicon dioxide.
(III) hydrochloric acid decomposition process: utilize hydrochloric acid to decompose, concentrate and making basic zirconium chloride (ZrOCl
28H
2o).
(IV) washing/filter progress: basic zirconium chloride is washed/filtered and makes zirconium hydroxide (Zr (OH)
4).
(V) fire/pulverizing process: zirconium hydroxide is fired, pulverized and makes zirconic powder.
No matter use any method of dry process and damp process, in order to generate pulverous zirconia, all utilize in bowl mill, jet pulverizer, ball mill any or they are combined to pulverize zirconic pulverizing process.The grinding machine using in pulverizing process and set basis thereof are as the zirconic particle diameter of target etc. and different., utilize the zirconia that dry process is manufactured, in pulverizing process, zirconic inner granular crack can occur herein, become the particle with most advanced and sophisticated sharp-pointed part.On the other hand, utilize the zirconia of damp process manufacture that inner granular crack occurs hardly in pulverizing process, at primary particle interface each other, be cut off (forming grain-boundary crack), sharp-pointed particle substantially can not taper off to a point as dry process.Its result, utilizes the primary particle of the zirconia particles that damp process makes different from dry process, becomes mellow and full shape.
The form that is second particle (aggregate of primary particle) as the zirconia particles that grinds abrasive particle use schematically shows this second particle (particle that utilizes damp process to make) in Fig. 3.The form of the aggregate that is a plurality of primary particles as the zirconia particles that grinds abrasive particle as shown in Figure 3.As shown in Figure 3, utilize the zirconia particles that damp process makes primary particle be shaped as mellow and full on the whole shape.
In this grinding step, about containing the zirconia particles that utilizes damp process manufacture as the effect of grinding abrasive particle and producing in lapping liquid, with reference to Fig. 4 and Fig. 5, describe.
Fig. 4 is the figure that the state in the hole portion 32 that glass blanket G is contained in carrier 30 is shown.As shown in Figure 4, in the carrier 30 of lapping device, accommodate under the state of glass blanket G, in order to make the glass blanket G can be from carrier 30 handling, between carrier 30 and glass blanket G, the direction of the major surfaces in parallel of glass blanket G (with) be provided with a little clearance C L in the horizontal direction.That is,, when the diameter (diameter of the bearing surface of glass blanket institute butt) that is designated as the hole portion 32 of D1, carrier 30 as the external diameter that grinds the glass blanket G of object is designated as D2, D2 > D1 sets up.Thus, in grinding, the zirconia (ZrO in lapping liquid
2) abrasive particle can enter the side wall surface Gt of glass blanket G and form the clearance C L between the side wall surface 30t of hole portion 32 of carrier 30.
In attrition process, glass blanket G is applied with load and for the direction with major surfaces in parallel, be not bound under the state in the hole portion 32 of carrier 30 by price fixing and moves in thickness of slab direction.Now, the side wall surface Gt of glass blanket G is connected to the side wall surface 30t that forms hole portion 32, and the zirconia abrasive particle that has simultaneously entered clearance C L is pressed into the side wall surface Gt of glass blanket G.State when the schematically illustrated zirconia particles of Fig. 5 (second particle) is pressed against the side wall surface Gt of glass blanket G, shows situation (situation of this grinding step) and the situations of utilizing zirconia particles that dry process manufacture different from this grinding step of utilizing the zirconia particles that damp process manufactures.Utilize the figure of situation of zirconia particles of dry process manufacture in order relatively to illustrate.
As shown in the top of Fig. 5, the zirconia abrasive particle using in this grinding step is owing to utilizing damp process manufacture, so primary particle is mellow and full, the second particle of the Main Morphology while grinding about conduct, and its surface is also mellow and full.Therefore,, even if zirconia abrasive particle is pressed against the side wall surface Gt of glass blanket G, the situation that penetrates side wall surface Gt is also few, grind rear oxidation zirconium particle residue low in the possibility of side wall surface Gt, in addition, the situation that scratches side wall surface Gt in grinding is few, is therefore difficult to produce scratch because of grinding.On the other hand, in the situation that the zirconia particles (bottom of Fig. 5) that utilizes dry process to manufacture, owing to having formed the particle with most advanced and sophisticated sharp-pointed part, easily penetrate side wall surface Gt, grind rear oxidation zirconium particle residue high in the possibility of side wall surface Gt, and scratch sometimes side wall surface Gt in grinding, easily because grinding, produce scratch.
The state of the schematically illustrated zirconia particles of Fig. 6 (second particle) when playing a role in attrition process between the first type surface Gp of glass blanket G and grinding pad 10, shows situation (situation of this grinding step) and the situations of utilizing zirconia particles that dry process manufacture different from this grinding step of utilizing the zirconia particles that damp process manufactures.Utilize the figure of situation of zirconia particles of dry process manufacture in order relatively to illustrate.
During attrition process, contact with the first type surface Gp of glass blanket G and what contribute to grind is each primary particle of zirconia particles that becomes the form of second particle, but as mentioned above because the zirconia abrasive particle using in this grinding step utilizes damp process manufacture, therefore primary particle is mellow and full, so be difficult to because producing scratch with contacting of first type surface Gp.On the other hand, in the situation that the zirconia particles (bottom of Fig. 6) that utilizes dry process to manufacture, there are many sharp-pointed positions as rock in the shape of the primary particle contacting with first type surface Gp, therefore easily by grinding, scratches first type surface Gp, easily because grinding produces scratch.
Generally speaking, in this grinding step, owing to containing in lapping liquid, utilize zirconia particles that damp process manufactures as grinding abrasive particle, therefore have advantages of that grinding rear oxidation zirconium particle is difficult to residue in the side wall surface Gt of glass blanket G and side wall surface Gt and first type surface Gp and is difficult to produce scratch.
(B) grind the particle diameter (being called " primary particle size " below) of the primary particle of abrasive particle
The primary particle size of zirconia abrasive particle is less, in attrition process, more increase (by more primary particle, contacting) with the contact point of the first type surface of glass blanket G, therefore the power that relatively each primary particle is subject to from price fixing reduces, its result, the scratch producing in glass blanket G reduces.On the other hand, if the primary particle of zirconia abrasive particle is too small, reduce with the contact area of glass blanket G, in attrition process, zirconia abrasive particle easily slides on glass blanket G thus, cannot effectively bring into play abrasive action, and grinding rate reduces.Thus, there is lower limit in the preferable particle size of the primary particle of zirconia abrasive particle.
In addition, if the primary particle size of zirconia abrasive particle increases, the power that relatively each primary particle is subject to from price fixing increases, its result, and the scratch producing in glass blanket G increases.Thus, there is higher limit in the preferable particle size of the primary particle of zirconia abrasive particle.
According to the result of inventor's repetition test, as the primary particle set in the zirconia particles scope that preferably particle diameter is 70nm～200nm of grinding abrasive particle, form.
The assay method of primary particle is shown in Fig. 7.As shown in Figure 7, with SEM (scanning electron microscope), zirconia abrasive particle is for example amplified to 30,000 times～100,000 times and observes, using the length of the major axis of primary particle (X1) with the mean value ((X1+X2)/2) of the length (X2) of minor axis as primary particle size.It should be noted that major axis and minor axis quadrature.
It should be noted that, the aspect ratio of the primary particle of present embodiment (the X1 ÷ X2 of Fig. 6) is 1.0～1.3, is mellow and full on the whole shape.
In addition, the index as the primary particle size with grinding abrasive particle in certain correlationship, known have a BET specific surface area.From the aspect of BET specific surface area, similarly according to the result of inventor's repetition test, the BET specific surface area of grinding the primary particle of abrasive particle is preferably 4m
2/ g～15m
2in the scope of/g.It should be noted that, BET specific surface area can be used flow-type specific area measuring device to be measured by BET one-point method by gas adsorption method.
In addition, according to the difference of creating conditions, contain sometimes the enough little zirconia particulate that cannot contribute to grainding capacity, but also can increase BET specific surface area by increasing the amount of this particulate.In this situation, contribute to the primary particle size of the zirconia particles of grainding capacity not change, and can change BET specific surface area.
(C) grind the particle diameter (being called " aggregate particle size " below) of the second particle of abrasive particle
The aggregate particle size of the zirconia abrasive particle of the Main Morphology when as attrition process, according to the idea same with above-mentioned primary particle size, lower limit and higher limit are determined.In addition, in the situation that aggregate particle size is excessive, the quantity that acts on the second particle of grinding under certain slurry concentration reduces, and grinding rate also likely reduces thus.So from the viewpoint of can effectively bringing into play abrasive action (guaranteeing grinding rate) and can reducing scratch, lower limit and the higher limit of second particle are determined.
According to the result of inventor's repetition test, the aggregate particle size (mean grain size D50) that grinds abrasive particle is preferably in the scope of 0.2 μ m～0.6 μ m.It should be noted that, in the situation that zirconia abrasive particle granulation in the situation that and with the degree cohesion of disintegration in attrition process, above-mentioned preferred particle size range is the scope of the value under the state that in attrition process, zirconia abrasive particle disperses.; in general; zirconia is used to ceramic purposes and electronic material purposes, fire resistive material purposes; in ceramic purposes; in order to improve zirconic density when pottery is manufactured; when zirconia is manufactured, by below mean grain size case of wet attrition to 1 μ m, in drying process, use that spraying is dried afterwards etc., thereby can deliberately aggregate particle size be increased to tens μ m left and right.Like this, the situation that deliberately increases aggregate particle size is called to granulation, but the easily disintegration in attrition process of zirconia after granulation.In addition, in the situation that zirconia by moisture cohesion etc. with weak cohesiveness cohesion, the easily disintegration in attrition process similarly of the zirconia of this cohesion.So the aggregate particle size that grinds abrasive particle is preferably used by attrition process the value under state that abrasive particle disperses is evaluated.
It should be noted that, mean grain size (D50) refers to, calculating from the little side of particle diameter, and the cumulative volume frequency of calculating with volume fraction reaches 50% particle diameter.
It should be noted that, the surfaceness (Ra) of carrying out the side wall surface of the first grinding glass blanket is before preferably below 0.1 μ m, more preferably below 0.05 μ m.The surfaceness of indication (Ra) can utilize contact pin type roughmeter to measure herein.By making the surfaceness of side wall surface of glass blanket so little, can increase the contact area with carrier 30, thereby the abrasive particle quantity entering between glass blanket G and carrier 30 increases, stressed being dispersed on more abrasive particle, thereby zirconia particles is difficult to penetrate the side wall surface of glass blanket G.In addition, if it is little to carry out the surfaceness of side wall surface of the glass blanket G before the first grinding, when contacting with carrier 30, be difficult to produce scar because of carrier 30, thereby the quantity of the zirconia abrasive particle of being caught by this scar reduces, also can indirectly reduce thus to penetrate the possibility of the side wall surface of glass blanket G.Therefore, carry out the first grinding during, be difficult to cause the situation that adheres to the side wall surface of glass blanket G such as penetrate because of zirconia abrasive particle.
The surfaceness of the end face that in addition, the side wall surface with glass blanket G in the hole of carrier 30 portion 32 contacts (wall of facing mutually with the side wall surface of glass blanket G) is below 5 μ m, is preferably below 3 μ m.The surfaceness of indication (Ra) can be used contact pin type roughmeter at circumferencial direction, to move pin for the end face of hole portion 32 herein, measures thus.By making the surfaceness of end face of hole portion 32 of carrier so little, can increase the contact area with glass blanket G, thereby the quantity increase that enters the abrasive particle in gap, force dispersion is on more abrasive particle, thereby zirconia particles is difficult to penetrate the side wall surface of glass blanket G.In addition, if the roughness of the end face of the hole portion 32 of carrier 30 is little, when its end face contacts with glass blanket G, also be difficult to produce scar on glass blanket G, the quantity of the zirconia abrasive particle of therefore being caught by this scar reduces, and also can indirectly reduce thus to penetrate the possibility of the side wall surface of glass blanket G.Carry out the first grinding during, the excessive roughening of the side wall surface of glass blanket G is suppressed, zirconia abrasive particle is difficult to adhere to the side wall surface of glass blanket G.
The manufacture method of present embodiment is suitable for manufacturing diameter, and to be greater than 2.5 inches and thickness of slab be the situation of the glass substrate for disc below 0.6mm.The aspect ratio of this glass substrate for disc (diameter/thickness of slab) is compared in the past higher.Therefore, the thickness of slab of glass blanket is thin, little with the contact area of the end face of carrier, so glass blanket is easily with stronger power and the end contact of carrier.In addition, the area of the first type surface of glass blanket is large, easily by grinding pad, is subject to friction force, so this also can make glass blanket with stronger power and the end contact of carrier.Reason based on such, zirconia particles is easily attached to the side wall surface of glass blanket, and the ratio that zirconia particles is attached to the side wall surface of glass blanket relatively easily increases.Yet, according to the manufacture method of present embodiment, as mentioned above, the second particle of the Main Morphology during about grinding as zirconia abrasive particle, because its surface is mellow and full, even if therefore zirconia abrasive particle is pressed into the side wall surface Gt of glass blanket G, the situation that penetrates side wall surface Gt is also few, therefore can suppress the generation of this problem.
(6-3) concave-convex surface of the first type surface of glass blanket
In the first grinding step, for the concave-convex surface of the first type surface of glass blanket, grind and make roughness (Ra) for 0.5nm is following and make micro-waviness (MW-Rq) for below 0.5nm.Herein, micro-waviness can be with RMS (Rq) value representation, fluctuation spacing in the region that RMS (Rq) value is 14.0mm～31.5mm as the radius of whole of first type surface is that the roughness of 100 μ m～500 μ m is calculated, for example, use optical profile type surface shape measuring machine to measure.
The roughness of first type surface is to represent according to the arithmetic average roughness Ra of JIS B0601:2001 defined, the roughness of first type surface is more than 0.006 μ m and in the situation below 200 μ m, for example can utilize contact pin type roughness measuring machine to measure, according to the method for stipulating in JIS B0633:2001, calculate.Consequently, roughness is in the situation below 0.03 μ m, for example, can utilize scanning type probe microscope (atomic force microscope; AFM) measure, according to the method for stipulating in JIS R1683:2007, calculate.In this application, can use the arithmetic average roughness Ra while measuring with the resolution of 256 * 256 pixels in the square mensuration region of 1 μ m * 1 μ m.
(7) chemical enhanced operation
Then, to the glass blanket after the first grinding, carry out chemical enhanced.
As chemical enhanced liquid, can use mixed liquor such as potassium nitrate (60 % by weight) and sodium sulphate (40 % by weight) etc.In chemical enhanced, chemical enhanced liquid is heated to for example 300 ℃～400 ℃, and the glass blanket through cleaning is preheated to for example 200 ℃～300 ℃, and then glass blanket floods for example 1 hour～5 hours in chemical enhanced liquid.During this dipping, in order to make two first type surface integral body of glass blanket by chemical enhanced, and two blocks of above glass blankets are held at side wall surface place, preferably with the state being contained in support, carry out.
So, by glass blanket is immersed in chemical enhanced liquid, the lithium ion on the top layer of glass blanket is replaced by the relative large sodion of the ionic radius in chemical enhanced liquid and potassium ion respectively with sodion, and glass blanket obtains Strongization.It should be noted that, the glass blanket through chemical enhanced processing is cleaned.For example, after cleaning with sulfuric acid, with pure water etc., clean.
(8) second grinding steps
Then, to implementing final grinding through glass blanket chemical enhanced and that fully cleaned.The final process redundancy grinding is below 5 μ m.In final grinding, for example, use the lapping device using in the first grinding.Now, the point different from the first grinding is that the kind hardness different with particle size and resin polishing material (Port リ ッ シ ャ) of free abrasive is different.As the free abrasive using in final grinding, such as use, be suspended in the particulates such as colloidal silica (particle size: diameter is 10nm～50nm left and right) in slurry.
Use neutral detergent, pure water, IPA etc. to clean the glass blanket after grinding, obtain thus glass substrate for disc.
Above, operation is illustrated the manufacture method of the glass substrate for disc of present embodiment one by one, but the order of operation is not limited to above-mentioned order.
It should be noted that, in the second grinding step, the particles such as colloidal silica are fed between the hole portion of glass blanket and carrier, and side wall surface that thus can abrading glass blanket and the zirconia particles that can be attached to side wall surface are removed.
In the manufacture method of above-mentioned glass substrate for disc, can carry out according to the order of chemical enhanced operation, the first grinding step, the second grinding step.In the situation that carrying out according to this process sequence, in chemical enhanced operation, preferably adjust chemical enhanced treatment conditions, so that the Fracture Toughness K of the above-mentioned glass blanket after chemical enhanced
1cin the measurement that utilizes Vickers, be 0.7[MPa/m
1/2] more than.Chemical enhanced by carrying out under these treatment conditions, can make by chemical enhanced and play the function of anti-cementation layer at the compression layer that the side wall surface of glass blanket forms, for preventing that the grinding abrasive particle as the first grinding step of rear operation from being the side wall surface that zirconia abrasive particle adheres to glass blanket.
In this situation, about the Fracture Toughness K of the glass blanket after chemical enhanced
1cin the measurement that utilizes Vickers, be 0.7[MPa/m
1/2] above chemical enhanced treatment conditions, for example can to chemical treatment conditions, carry out various variations in advance and decide.It should be noted that Fracture Toughness K
1c1.0[MPa/m more preferably
1/2] more than.In addition, further 1.3[MPa/m more preferably
1/2] more than.Fracture Toughness K
1cmore high more preferred, to Fracture Toughness K
1cthe upper limit special setting not.Herein, Fracture Toughness K
1ccan measure by the sharp-pointed diamond penetrator of known Vickers being pressed into the method for glass blanket.That is, Fracture Toughness K
1cthe impression size of pressure head and the length of the crackle that produces from the corner of impression that residue in glass blanket when being pressed into Vickers pressure head are obtained according to following formula.P be Vickers pressure head be pressed into load [N], a is half length [m] of the diagonal line length of Vickers impression.E is the Young modulus [Pa] of glass blanket, half length [m] that C is fracture length.
K
1c＝0.026·E
1/2·P
1/2·a/C
3/2
In addition, chemical enhanced treatment conditions comprise the kind (such as the mixing ratio of potassium nitrate and sodium sulphate) of chemical enhanced liquid, the temperature of chemical enhanced liquid, chemical enhanced processing time etc.In addition, also can select the Fracture Toughness K of the glass blanket after chemical enhanced
1cfor above-mentioned 0.7[MPa/m
1/2] glass of above glass blanket forms.
It should be noted that, be to using the first type surface of glass blanket as Fracture Toughness K in present embodiment
1cmeasuring object, but for chemical enhanced, the side wall surface of the end face of glass blanket also with first type surface carried out comparably chemical enhanced, so Fracture Toughness K of the side wall surface of glass blanket
1cfracture Toughness K with first type surface
1cmeasurement result identical, can be with the Fracture Toughness K of first type surface
1creplace.
[disk]
For disk, can use glass substrate for disc to obtain as follows.
Disk configuration example is as being: on the first type surface of glass substrate for disc (below referred to as " substrate "), certainly approach main surface at least successively lamination have adhesion layer, bottom, magnetosphere (magnetic recording layer), protective seam, lubricating layer.
For example, substrate is imported in the film formation device after vacuumizing, utilize DC magnetron sputtering method in Ar atmosphere, on the first type surface of substrate, film forming goes out adhesion layer to magnetosphere successively.As adhesion layer, for example CrTi can be used, as bottom, for example CrRu can be used.As magnetosphere, can use for example CoPt to be associated gold.In addition, also can form L
10the CoPt of ordered structure is associated gold, FePt is associated gold and forms the magnetosphere that HAMR (Heat Assisted Magnetic Recording) is used.After above-mentioned film forming, for example, by CVD method, use C
2h
4film forming goes out protective seam, and then effects on surface imports the nitrogen treatment of nitrogen, can form magnetic recording media thus.Afterwards, for example, by dip coated method, on protective seam, be coated with PFPE (PFPE), can form lubricating layer thus.
The disk of made is preferably arranged in the HDD (Hard Disk Drive) as magnet record playback device together with being equipped with the magnetic head of DFH (Dynamic Flying Height) control gear.
[embodiment, comparative example]
In order to confirm the effect of manufacture method of the glass substrate for disc of present embodiment, by the glass substrate for disc of manufacturing, made the disk of 2.5 inches.The glass substrate for disc of the made unbodied alumina silicate glass that following composition forms of serving as reasons.
[composition of glass]
By the following unbodied alumina silicate glass forming that forms: be converted into oxide benchmark, with a % by mole expression, contain 50%～75% SiO
2; 1%～15% Al
2o
3; Add up to 5%～35% the Li that is selected from
2o, Na
2o and K
2at least a kind of composition in O; Add up to 0%～20% at least a kind of composition in MgO, CaO, SrO, BaO and ZnO that is selected from; And the ZrO that is selected from that adds up to 0%～10%
2, TiO
2, La
2o
3, Y
2o
3, Ta
2o
5, Nb
2o
5and HfO
2in at least a kind of composition.
Carry out successively each operation of manufacture method of the glass substrate for disc of present embodiment.
Herein,
(1) compression-moulding methods using in the manufacture method of the glass substrate for disc of recording in TOHKEMY 2011-138589 communique is used in the moulding of glass blanket.In polishing, having used mean grain size is the alumina series free abrasive of 20 μ m.
(4) in end surface grinding, the mean value (D50) that uses particle diameter be the cerium oxide of 1.0 μ m as free abrasive, utilize abrasive brush to grind the more than two glass blanket clipping filling material lamination between glass blanket.
(5), in the grinding that utilizes bonded-abrasive, use the grinding attachment that diamond chip is sticked on upper price fixing, lower price fixing to carry out grinding.
(6), in the first grinding, use the lapping device of Fig. 1 and Fig. 2 to grind 60 minutes.Detailed grinding condition is as follows.
(7) in chemical enhanced, the mixed liquors of use potassium nitrate (60 % by weight) and sodium nitrate (40 % by weight) etc. are as chemical enhanced liquid, the temperature that makes chemical enhanced liquid is 350 ℃, and the glass blanket that is preheated in advance 200 ℃ is flooded 4 hours in chemical enhanced liquid.
(8) in the second grinding, other same lapping device of lapping device of use and Fig. 1 and Fig. 2, using particle diameter is the colloidal silica of 10 μ m～50 μ m, grinds official hour.Thus, make the arithmetic average roughness Ra (JIS B0601:2001) of first type surface for below 0.15nm.Glass blanket after using neutral cleaning fluid and alkaline cleaning fluid to final grinding cleans.Thus, obtained glass substrate for disc.
The grinding condition > that < first grinds
Grinding pad: hard polyaminoester pad (JIS-A hardness: 80～100)
Grind load: 120g/cm
2
Price fixing rotating speed: 30rpm
Lapping liquid supply flow rate: 3000L/min
Lapping liquid: the zirconia (ZrO that contains 10 % by weight
2) abrasive particle.The zirconia abrasive particle of embodiment all utilizes damp process to make.The zirconia abrasive particle of comparative example utilizes dry process to make.
In making the process of glass substrate for disc, the setting of the zirconia abrasive particle in the first grinding of change (6), after the grinding rate in evaluation attrition process and attrition process, glass blanket has or not scratch, and its result is the result shown in table 1 and table 2.It should be noted that, be to have carried out above-mentioned evaluation for implemented cleaning and dried sample after the first grinding step.
Herein, the aggregate particle size of zirconia abrasive particle (mean grain size D50) is used particle diameter/particle size distribution device to measure by light scattering method.Mean grain size D50 refers to, the cumulative volume of the powder group in the size-grade distribution by light scattering determining is being made as to 100% while obtaining cumulative volume frequency, and its cumulative volume frequency reaches the particle diameter of 50% point.About primary particle size, utilize scanning electron microscope that zirconia abrasive particle is amplified to 30,000 times～100,000 times, utilize the method shown in Fig. 7 to measure.In addition, BET specific surface area is to utilize flow-type specific area measuring device by gas adsorption method, measured by BET one-point method.
In table 1 and table 2, the metewand that grinding rate and scratch are evaluated is as described below.
The metewand of grinding rate
About the evaluation of grinding rate, measure first grinding rate, based on following benchmark, evaluate.◎, zero or △ be qualified.
◎: be greater than 1.8 μ m/ minute
Zero: be greater than 1.6 μ m/ minutes and be below 1.8 μ m/ minutes
△: be greater than 1.4 μ m/ minutes and be below 1.6 μ m/ minutes
*: below 1.4 μ m/ minutes
The metewand that scratch is evaluated
During scratch is evaluated, for the first type surface after the attrition process of the glass blanket of the N=200 sheet of each embodiment, the shady deal internal radiation spotlight in CR and carry out visual examination, the ratio based on visual examination OK product is evaluated.Visual examination OK product are at the first type surface of glass blanket, not confirm the goods of scratch by visual examination, and visual examination NG product are by visual examination, at the first type surface of glass blanket, to confirm the goods of scratch.◎, zero or △ be qualified.
◎: visual examination OK product are the more than 95% of integral body
Zero: visual examination OK product are for whole more than 90% and be less than 95%
△: visual examination OK product are for whole more than 70% and be less than 90%
*: visual examination OK product are less than 70% of integral body
[table 1]
※ mean grain size D50 is 0.4 μ m.
[table 2]
As shown in Table 1, in the situation that the zirconia particles that utilizes dry process to make confirms scratch and evaluates defective.In the time of in the scope that the primary particle size that utilizes the zirconia particles of damp process making is 70nm～200nm, grinding rate and scratch are evaluated both for good result.In addition, as shown in Table 2, as the BET specific surface area of grinding the zirconia particles of abrasive particle use, be 4m
2/ g～15m
2in the time of in the scope of/g, grinding rate and scratch are evaluated both for good result.
In addition, known: if make the mean grain size (D50) of zirconia particles, be in the scope of 0.2 μ m～0.6 μ m, grinding rate and scratch are evaluated both for better result.
Then, on the glass substrate for disc of embodiment 1～13 and comparative example, lamination adhesion layer, bottom, magnetosphere (magnetic recording layer), protective seam, lubricating layer are made disk, and the suspension amount that slides head is set as to 7nm and slides inspection.Its result, checks that to each embodiment the yield rate (passed examination rate) of 100 is more than 90%, all qualified.
On the other hand, in having used the comparative example of the zirconia abrasive particle that utilizes dry process making, yield rate is lower than 90%, defective.In addition, by SEM/EDX, to sliding detected bad position in inspection, observe, found that foreign matter.For found foreign matter, carried out composition analysis, result is the foreign matter from zirconic lapping compound.That is, can think: the zirconia particles using in grinding step is attached to glass blanket and is found as foreign matter in attrition process.
It should be noted that, not according to (6) first grinding, (7) chemical enhanced, (8) second process sequences that grind, and the orders change process sequences chemical enhanced according to (7), (6) first grindings, (8) second are ground have been made glass substrate for disc.Now, about the method for making of the zirconia abrasive particle in the first grinding, the primary particle size of zirconia abrasive particle, aggregate particle size D50 are identical with the embodiment 3 of table 1.In addition, suitably change strengthening temperature and dip time in chemical enhanced operation, made as described in Table 3 Fracture Toughness K
1ccarried out the glass substrate for disc (embodiment 14,15 of table 3) of various variations.The evaluation result of the glass blanket after the first grinding is now shown in table 3.
[table 3]
As shown in table 3, known: by before the first grinding at Fracture Toughness K
1cfor 0.7[MPa/m
1/2] carry out under above chemical enhanced treatment conditions chemical enhancedly, can obtain better scratch evaluation.Think that this is because the compression layer forming by the chemical enhanced side wall surface at glass substrate is as the anti-cementation layer performance function of the zirconia abrasive particle using in the first grinding of carrying out thereafter.
Next, make the method for making of zirconia abrasive particle, the primary particle size of zirconia abrasive particle, aggregate particle size D50 are identical with the embodiment 8 of table 1, use the different carrier of surfaceness of end face in the first lapping device grinding to carry out the first grinding, made glass substrate for disc (embodiment 16～18 of table 4).Now, process sequence carries out according to (6) first grindings, (7) orders chemical enhanced, (8) second grindings similarly to Example 8, has made glass substrate for disc.The evaluation result of the glass blanket after the first grinding is now shown in table 4.
[table 4]
As shown in table 4, during scratch is evaluated, if the surface roughness Ra of the end face of carrier be 5 μ m with next be evaluated as good, if the surface roughness Ra of the end face of carrier be 3 μ m with next be evaluated as better.Think this be because, the surfaceness of the end face of carrier is less, the quantity that enters the zirconia abrasive particle between glass blanket and carrier more increases, stressed being dispersed on more abrasive particle, thereby zirconia particles is difficult to penetrate the side wall surface of glass blanket.
Above, the manufacture method of glass substrate for disc of the present invention is had been described in detail, but the invention is not restricted to above-mentioned embodiment, obviously also can in the scope that does not depart from purport of the present invention, carry out various improvement, change.
Claims (9)
1. the manufacture method of a glass substrate for disc, it has following grinding step: by least having a pair of first type surface, remain in carrier with the glass substrate of the bagel type of 2 side wall surfaces of formation endoporus and profile, under this state, with the grinding pad of installing in grinding price fixing, clamp described a pair of first type surface, to described a pair of first type surface, supply with lapping liquid, utilize the planet wheel of described carrier to move to grind described glass substrate simultaneously
This manufacture method is characterised in that, described lapping liquid contains and utilizes zirconia particles that damp process manufactures as grinding abrasive particle.
2. the manufacture method of glass substrate for disc as claimed in claim 1, is characterized in that, described zirconia particles is that particle diameter is that primary particle set in the scope of 70nm～200nm forms.
3. the manufacture method of glass substrate for disc as claimed in claim 1, is characterized in that, the BET specific surface area of described zirconia particles is in 4m
2/ g～15m
2in the scope of/g.
4. the manufacture method of glass substrate for disc as claimed in claim 2 or claim 3, is characterized in that, in the scope of the mean grain size D50 of described zirconia particles in 0.2 μ m～0.6 μ m.
5. the manufacture method of the glass substrate for disc as described in any one in claim 2～4, it is characterized in that, when the length of the major axis of the primary particle of described zirconia particles being made as to X1, the length of the minor axis with major axis quadrature is made as to X2, X1/X2 is 1.0～1.3.
6. the manufacture method of the glass substrate for disc as described in any one in claim 1～4, is characterized in that, the surfaceness of the end face of the described carrier contacting with the side wall surface of described glass substrate is below 5 μ m.
7. the manufacture method of the glass substrate for disc as described in any one in claim 1～5, it is characterized in that, the surfaceness of using the lapping liquid with described zirconia particles to grind the side wall surface of previous glass substrate is counted below 0.1 μ m with arithmetic average roughness Ra.
8. the manufacture method of the glass substrate for disc as described in any one in claim 1～7, is characterized in that, has following chemical enhanced operation after described grinding step: at the Fracture Toughness K of described glass substrate
1cin the measurement that utilizes Vickers, be 0.7MPa/m
1/2under above treatment conditions, to described glass substrate, carry out chemical enhanced.
9. the manufacture method of the glass substrate for disc as described in any one in claim 1～8, is characterized in that, the diameter of described glass substrate for disc is greater than 2.5 inches of sizes and thickness of slab is below 0.6mm.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2012083025 | 2012-03-30 | ||
| JP2012-083025 | 2012-03-30 | ||
| PCT/JP2013/055593 WO2013146090A1 (en) | 2012-03-30 | 2013-02-28 | Method for manufacturing glass substrate for magnetic disk |
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| Publication Number | Publication Date |
|---|---|
| CN104137181A true CN104137181A (en) | 2014-11-05 |
Family
ID=49259365
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201380009608.4A Pending CN104137181A (en) | 2012-03-30 | 2013-02-28 | Method for manufacturing glass substrate for magnetic disk |
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|---|---|
| JP (1) | JPWO2013146090A1 (en) |
| CN (1) | CN104137181A (en) |
| WO (1) | WO2013146090A1 (en) |
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| CN110651327A (en) * | 2017-09-29 | 2020-01-03 | Hoya株式会社 | Glass spacer and hard disk drive device |
| CN113913156A (en) * | 2017-10-31 | 2022-01-11 | Hoya株式会社 | Polishing liquid, method for producing glass substrate, and method for producing magnetic disk |
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- 2013-02-28 JP JP2014507586A patent/JPWO2013146090A1/en active Pending
- 2013-02-28 WO PCT/JP2013/055593 patent/WO2013146090A1/en active Application Filing
- 2013-02-28 CN CN201380009608.4A patent/CN104137181A/en active Pending
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| TW200712184A (en) * | 2005-05-20 | 2007-04-01 | Nissan Chemical Ind Ltd | Production process of polishing composition |
| CN101542606A (en) * | 2007-05-30 | 2009-09-23 | 东洋钢钣株式会社 | Method of surface finish for glass substrate for magnetic disk and glass substrate for magnetic disk |
| US20110151282A1 (en) * | 2009-12-22 | 2011-06-23 | Asahi Glass Company, Limited | Method for manufacturing glass substrate for data storage medium and glass substrate |
| WO2012029857A1 (en) * | 2010-08-31 | 2012-03-08 | Hoya株式会社 | Method for producing glass substrate for magnetic disks, and method for producing magnetic disk |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110651327A (en) * | 2017-09-29 | 2020-01-03 | Hoya株式会社 | Glass spacer and hard disk drive device |
| CN110651327B (en) * | 2017-09-29 | 2021-10-15 | Hoya株式会社 | Glass spacer and hard disk drive device |
| US11244706B2 (en) | 2017-09-29 | 2022-02-08 | Hoya Corporation | Glass spacer and hard disk drive apparatus |
| US11705158B2 (en) | 2017-09-29 | 2023-07-18 | Hoya Corporation | Method for manufacturing ring-shaped glass spacer |
| CN113913156A (en) * | 2017-10-31 | 2022-01-11 | Hoya株式会社 | Polishing liquid, method for producing glass substrate, and method for producing magnetic disk |
| CN113913156B (en) * | 2017-10-31 | 2022-06-24 | Hoya株式会社 | Polishing liquid, method for producing glass substrate, and method for producing magnetic disk |
| US11680187B2 (en) | 2017-10-31 | 2023-06-20 | Hoya Corporation | Polishing liquid, method for manufacturing glass substrate, and method for manufacturing magnetic disk |
Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2013146090A1 (en) | 2015-12-10 |
| WO2013146090A1 (en) | 2013-10-03 |
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