CN105431904A - Glass substrate for magnetic disk, method of producing glass substrate for magnetic disk, and magnetic disk - Google Patents

Glass substrate for magnetic disk, method of producing glass substrate for magnetic disk, and magnetic disk Download PDF

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Publication number
CN105431904A
CN105431904A CN201480042395.XA CN201480042395A CN105431904A CN 105431904 A CN105431904 A CN 105431904A CN 201480042395 A CN201480042395 A CN 201480042395A CN 105431904 A CN105431904 A CN 105431904A
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China
Prior art keywords
glass substrate
glass
disc
cao
compressive stress
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CN201480042395.XA
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CN105431904B (en
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岩田胜行
桥本和明
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Krones AG
Hoya Corp
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Hoya Corp
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    • 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
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C21/00—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
    • C03C21/001—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions
    • C03C21/002—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions to perform ion-exchange between alkali ions
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/078—Glass compositions containing silica with 40% to 90% silica, by weight containing an oxide of a divalent metal, e.g. an oxide of zinc
    • 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
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/739—Magnetic recording media substrates
    • G11B5/73911—Inorganic substrates
    • G11B5/73921—Glass or ceramic substrates

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Ceramic Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Surface Treatment Of Glass (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Glass Compositions (AREA)
  • Magnetic Record Carriers (AREA)

Abstract

In the present invention, a glass substrate for a magnetic disk contains, as the glass composition, 0.1-1 mol% of Li2O. A fracture toughness value KIC[Mpa-m 1/2 ] of the glass substrate is at least 1[Mpa-m 1/2 ]. A compressive stress layer formed by chemical strengthening is provided on the glass substrate surface, and the depth D[[mu]m] of the compressive stress layer satisfies D>=57-KIC -1.6 and D>=20[[mu]m]. The glass substrate is obtained by adjusting the chemical strengthening conditions.

Description

The manufacture method of glass substrate for disc, glass substrate for disc and disk
Technical field
The present invention relates to glass substrate for disc, the manufacture method of glass substrate for disc and disk.
Background technology
The disk in the past used as one of information recording carrier preferably uses glass substrate.Current, the requirement of answering the memory capacity in hard disk drive to increase, seeks the densification of magnetic recording.In recent years, in order to make the magnetic recording densification of disk, propose the recording medium of the energy assisted magnetic recording mode of the magnetospheric HAMR (Heat Assisted Magnetic Recording) mode forming iron-platinum on the glass substrate etc.The glass substrate used in recording medium about this power assist mode; when forming the magnetosphere of iron-platinum, glass substrate is exposed to the high temperature of about 700 DEG C, therefore requires to be maintained as the physical strength of glass substrate and vitrification point (ガ ラ ス translocation moves a temperature) is higher.
On the other hand, it is also known that implement chemical intensification treatment on the glass substrate to improve physical strength thus form compressive stress layers on the glass substrate.The compression stress value of compressive stress layers or the degree of depth of compressive stress layers are tried to achieve by Babinet compensator method.It is also known that provide the method for the glass substrate of the attribute (profile) with compression stress or the drawing stress being suitable for glass substrate for disc according to the degree of depth of the compression stress value utilizing Babinet compensator method to try to achieve and compressive stress layers.Such as, be known to the following glass substrate implementing chemical intensification treatment: in order to have higher resistance to impact, when the most external stressor layers of the first type surface of glass substrate give as security length be less than 49.1 μm and set that between described first type surface and compression stress, formed angle is as θ in based on the stress attribute of Babinet compensator method time, the value y specified by this θ is that described most external stressor layers gives as security below length (patent documentation 1).
In addition, be known to take into account excellent impact resistance and the data storage medium glass substrate of both stabilizations of disk shape and its manufacture method.Specifically, the manufacture method of this glass substrate comprises and be impregnated in mixed melting salt by glass substrate, and forms the chemical intensification treatment engineering of compression layer on the surface of this glass substrate and the back side.Now, glass substrate contains lithium ion as alkaline components, mixed melting salt contains sodium nitrate, potassium nitrate and is expressed as the lithium nitrate of 1 ~ 6% by mass percent, glass substrate be impregnated in more than 325 DEG C the processing time of in mixed melting salt less than 30 minutes in the treatment temperature of less than 475 DEG C, and meet following formula.Wherein, T is treatment temperature (unit: K), and t is processing time (unit: second).1900≤T×log(t2)≤2900。Be well known that, in this glass substrate, the destruction toughness value that setting utilizes the casting die plunging based on JISR1607 to measure and obtains is more than 1.2, can improve physical strength (patent documentation 2).
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 2009-099251 publication
Patent documentation 2: Japanese Unexamined Patent Publication 2011-134367 publication
Summary of the invention
The problem that invention will solve
But; in the glass material that the glass substrate for disc obtained with above-mentioned known technology uses; usual vitrification point is less than 600 DEG C; therefore, when glass substrate for disc being in the past used for the recording medium of above-mentioned power assist mode, being exposed in above-mentioned high temperature and easily producing the warpage of substrate or isolate.Therefore, in the glass substrate of the recording medium of power assist mode, even if the higher glass substrate can not applied in the past of the physical strength under room temperature.
Improve vitrification point, be known to reduce Li 2the amount of O, but due in the glass substrate employing this glass, the amount of Li is less, even if therefore use the liquid comprising the known chemical enhanced fuse salt of Na or K etc. to carry out chemical treatment, the compressive stress layers that physical strength brings up to the degree required by glass substrate for disc also can be formed.
Therefore, the object of the present invention is to provide the disk that reliably there is the glass substrate for disc of the physical strength being suitable for disk and the manufacture method of glass substrate for disc and employ this glass substrate for disc.
For solving the means of problem
(mode 1)
A mode of the present invention is the glass substrate for disc of following structure.
This glass substrate for disc contains with the Li % by mole representing 0.1% ~ 1% 2o, as glass ingredient, destroys toughness value K iC[MPam 1/2] be 1 [MPam 1/2] more than, be provided with based on chemical enhanced compressive stress layers at glass baseplate surface, the degree of depth D [μm] of described compressive stress layers meets D>=57K iC -1.6, and D>=20 [μm].
In addition, preferably toughness value K is destroyed iC[MPam 1/2] be 2.5 [MPam 1/2] below.In addition, preferred depth D is less than 150 μm.
(mode 2)
In addition, according to the glass substrate for disc of mode 1, wherein, the vitrification point Tg of described glass substrate for disc is more than 650 DEG C.
(mode 3)
In addition, the glass substrate for disc according to mode 1 or 2, wherein, described glass substrate for disc contains % by mole to represent, the SiO of 55% ~ 78% 2, the Li of 0.1% ~ 1% 2o, the Na of 2% ~ 15% 2o, and add up to MgO, CaO, SrO and BaO of 10% ~ 25%, as glass ingredient, the amount of CaO is less than 0.20 relative to the mol ratio (CaO/ (MgO+CaO+SrO+BaO)) of the total amount of MgO, CaO, SrO and BaO.
(mode 4)
Glass substrate for disc according to any one in mode 1 ~ 3, wherein, the thickness of slab of described glass substrate for disc is 0.3 ~ 1.5mm.
Now, be more than 0.5mm when making described glass substrate for disc become nominal is the size of more than 2.5 inches of sizes.
(mode 5)
According to the glass substrate for disc in mode 1 ~ 4 described in any one, wherein, as the glass ingredient of described glass substrate for disc, be made up of the alumina silicate glass not comprising Ca.
(mode 6)
A kind of disk, wherein, this disk is included in the glass substrate for disc described in any one in mode 1 ~ 5 and is formed at the magnetosphere on surface of described glass substrate.
(mode 7)
A manufacture method for glass substrate for disc, wherein, the manufacture method of this glass substrate for disc comprises: make the process of glass substrate, wherein, this glass substrate is plate-like, containing with the Li % by mole representing 0.1% ~ 1% 2o, and carry out chemical enhanced process, by implementing described chemical enhanced to described glass substrate, make to destroy toughness value K iC[MPam 1/2] be 1 [MPam 1/2] more than, by described chemical enhanced and the degree of depth D [μm] being arranged at the compressive stress layers of glass baseplate surface meets D>=57K iC -1.6, and D>=20 [μm].
(mode 8)
The manufacture method of the glass substrate for disc according to mode 7, wherein, in described chemical enhanced process, is be impregnated in by described glass substrate to comprise KNO 3and NaNO 3mixed melting salt liquid in process, described mixed melting salt comprises the KNO of 55% ~ 85% mass percent 3.
(mode 9)
The manufacture method of the glass substrate for disc according to mode 7 or 8, preferably, the described glass substrate after described chemical treatment contains % by mole to represent, the SiO of 55% ~ 78% 2, the Li of 0.1% ~ 1% 2o, the Na of 2% ~ 15% 2o, and MgO, CaO, SrO and BaO of adding up to 10% ~ 25%, as glass ingredient, the amount of CaO is less than 0.20 relative to the mol ratio CaO/ (MgO+CaO+SrO+BaO) of the total amount of MgO, CaO, SrO and BaO.
(mode 10)
The manufacture method of the glass substrate for disc according to any one in mode 7 ~ 9, wherein, the thickness of slab of described glass substrate is 0.3 ~ 1.5mm.
Now, described thickness of slab is preferably more than 0.5mm.
(mode 11)
The manufacture method of the glass substrate for disc according to any one in mode 7 ~ 10, wherein, described glass substrate is made up of the alumina silicate glass not comprising Ca.
Invention effect
According to above-mentioned mode, the glass substrate for disc reliably with the physical strength being suitable for disk can be provided.
Accompanying drawing explanation
Fig. 1 is the stereographic map of the glass substrate for disc of present embodiment.
Fig. 2 illustrates that the scar of glass substrate applies the figure of the corresponding relation between destruction toughness value before treatment and physical strength (bending strength).
Fig. 3 is the compressive stress layers of the glass substrate that present embodiment is described and the figure of tension stress layer.
Fig. 4 is the figure of the test method that physical strength (bending strength) is described.
Fig. 5 is the figure of the scope of the glass substrate that present embodiment is shown.
Embodiment
Below the glass substrate for disc of present embodiment is described in detail.
[glass substrate for disc]
Fig. 1 is the stereographic map of the glass substrate for disc 10 (hereinafter referred to as " glass substrate 10 ") of present embodiment.As shown in Figure 1, glass substrate 10 is circular plate shape, is formed as core and is hollowed out the ring-type of concentrically toroidal.In glass substrate 10, at least the surface of glass substrate is chemical enhanced, is formed with compressive stress layers on the surface of glass plate 10.
For glass substrate 10, containing with the Li % by mole representing 0.1% ~ 1% 2o is as glass ingredient.As the mechanical property of glass substrate 10, destroy toughness value K iC[MPam 1/2] be 1 [MPam 1/2] more than.Be provided with on the surface of glass substrate 10 based on chemical enhanced compressive stress layers, the degree of depth D [μm] of this compressive stress layers meets D>=57K iC -1.6, and D>=20 [μm].More preferably meet and destroy toughness value K iC[MPam 1/2] be 1.2 [MPam 1/2] more than, the degree of depth D [μm] of compressive stress layers is D>=70K iC -1.6and D>=35 [μm].
The vitrification point Tg of the glass of such glass substrate 10 is preferably more than 650 DEG C.In this case, although glass substrate 10 can be used in various glass substrate for disc, preferably can be used in the glass substrate for disc of power assist mode.
Wherein, toughness value K is destroyed iC[MPam 1/2] be preferably 2.5 [MPam 1/2] below.In addition, degree of depth D is preferably less than 150 μm.
When use glass substrate 10 make disk time, by the first type surface at glass substrate 10 at least film forming magnetosphere make disk.
The magnetic material that it is principal ingredient that magnetosphere such as comprises with the alloy of Fe and/or Co and Pt.There is the disk that this magnetospheric disk is preferred for power assist mode.As the magnetic material being principal ingredient with the alloy of Fe and/or Co and Pt, Fe-Pt magnetic material, Co-Pt magnetic material or Fe-Co-Pt magnetic material can be enumerated.
When forming above-mentioned magnetosphere, after the first type surface film forming of the glass substrate magnetic material that is principal ingredient with the alloy of Fe and/or Co and Pt, carry out annealing in process.At this, the film-forming temperature of above-mentioned magnetic material is above the high temperature of 500 DEG C under normal circumstances.And in order to make these magnetic materials consistent at film forming post crystallization orientation, at the temperature exceeding film-forming temperature, carry out above-mentioned annealing in process.Therefore, under use Fe-Pt magnetic material, Co-Pt magnetic material or Fe-Co-Pt magnetic material form magnetospheric situation, glass substrate is exposed in above-mentioned high temperature.From having superior thermotolerance this point, the preferred vitrification point of glass substrate 10 of present embodiment is more than 650 DEG C.Vitrification point Tg preferred lower limit is 660 DEG C, more preferred lower limit is 665 DEG C, and preferred lower limit is 670 DEG C, and preferred lower limit is 675 DEG C further.But if exceedingly improve vitrification point Tg, then chemical intensification treatment temperature described later uprises, cause the pyrolysis of fuse salt and the surface of attack glass substrate time chemical enhanced, therefore the preferred upper limit by vitrification point Tg is set as 740 DEG C.In addition, vitrification point Tg is in chemical enhanced front and back substantial constant.Even if the glass substrate 10 be made up of the glass of such vitrification point Tg forms the magnetosphere of Fe-Pt magnetic material, Co-Pt magnetic material or Fe-Co-Pt magnetic material on the glass substrate 10 and after carrying out annealing in process, also has higher flatness.
Make above-mentioned vitrification point Tg high than ever, realized by adjustment glass ingredient.Specifically, by suppress the alkalinous metal such as Li, Na containing composition, can vitrification point Tg be improved.
In this, contain for the glass of the glass substrate 10 of present embodiment with the Li % by mole representing 0.1% ~ 1% 2o.Li 2the containing ratio of O is preferably 0.1% ~ 0.6%, is more preferably 0.1% ~ 0.3%.
The present application person, for the glass substrate of above-mentioned glass ingredient, is conceived to the chemical intensification treatment used in this manufacture method, meets carried out various research as the compressive stress layers that the physical strength required by disk is such to formation.
In general, as the physical strength of glass substrate for disc, use known bending strength.The bending strength of glass substrate for disc is following value: make the determined value of the load of breaking glass panel when being placed in by the steel ball larger than the circular hole of the central opening at glass substrate and above-mentioned circular hole applying load to steel ball gradually.Can say that the test method of this bending strength simulates the physical strength of the glass substrate for disc on the rotary main shaft that is fixed in hard disk drive.On the other hand, will utilize based on the destruction toughness value K measured by the casting die plunging of JISR1607 in the past always iC[MPam 1/2] as the index of the physical strength of glass substrate.
Fig. 2 has investigated the above-mentioned destruction toughness value K on the new glass substrate made as glass substrate for disc, the glass substrate of state that namely do not damage at the aftermentioned inner side end of the circular at glass substrate like that and the peripheral part of this circular hole iC[MPam 1/2] and the value of bending strength between the figure of corresponding relation.Learn according to Fig. 2, destroy toughness value K iChigher, then bending strength is also roughly higher.But above-mentioned corresponding relation is the use of the result as lower glass substrate, glass substrate when this glass substrate is new product, does not damage at the peripheral part of the circular hole of the inner side end of the circular of glass substrate and the first type surface of glass substrate.The actual peripheral part being arranged at the circular hole of the inner side end of the circular at the center of glass substrate for disc and the first type surface of glass substrate, before being fixed in the rotary main shaft of hard disk drive, produce small damage with various component contact sometimes.Such as, when in order to be fixed on rotary main shaft with rotary main shaft self-contact and to glass substrate carry out position adjust time, or when utilizing touch sensor to extract inspection to glass substrate, the peripheral part of the inner side end of the circular of glass substrate and the circular hole of first type surface produces damage sometimes.Especially, based in the magnetic recording of future generation of energy assisted magnetic recording mode, track density is high, therefore especially needs strictly to carry out the location of disk relative to main shaft to suppress guiding error (trackingmistake).And the circular hole periphery when carrying out this adjustment operation easily at glass substrate produces damage.Present inventor finds, due to glass substrate as described above by before actual assembled to hard disk drive the damage that produces, sometimes corresponding relation as shown in Figure 2 may not be set up.Under these circumstances, because the incidence (fraction defective) that bending strength declines is not in permissible range, the therefore decrease in yield of glass substrate for disc.And, find especially at Li 2in the glass substrate that the amount of O is lower, above-mentioned phenomenon can be observed significantly.
For being false of such a above-mentioned corresponding relation, the present application person judges, except destroying toughness value K iCoutside also need other index.Therefore, various change has been carried out to the glass ingredient of glass substrate and the chemically treated condition implemented on the glass substrate, and investigate because the formation of the damage of the inner side end of glass substrate causes bending strength to decline and the fraction defective of the glass substrate of the unacceptable product that can not provide as product is provided, and conscientiously have studied the index that this fraction defective is exerted one's influence.
Its result is thought, even if even if to be exposed to obtain glass substrate in the high temperature of about 700 DEG C also not warpage be assembled into the glass substrate that HDD also do not isolate after having carried out various adjustment, by Li 2the amount of O is adjust chemical enhanced treatment conditions in the glass substrate of 0.1 ~ 1 % by mole, can reduce the fraction defective of glass substrate.And think, become in the glass substrate of certified products in the screening of qualification rate (=1-fraction defective) employing glass substrate, destroy toughness value K iC1 [MPam 1/2] more than, and be more than certain steady state value by the degree of depth of the chemical enhanced compressive stress layers in glass surface formation, and need ratio according to destruction toughness value K iCthe value determined is large.
That is, by Li 2the amount of O is in the glass substrate 10 of few glass formation of 0.1 ~ 1 % by mole, destroys toughness value K iC[MPam 1/2] be 1 [MPam 1/2] more than, be provided with based on chemical enhanced compressive stress layers at glass baseplate surface, the degree of depth D [μm] of compressive stress layers meets D>=57K iC -1.6and D>=20 [μm].Like this, by specifying the destruction toughness value K of glass substrate iCwith the degree of depth D of compressive stress layers, glass substrate reliably has the physical strength being suitable for disk.In addition, known, as destruction toughness value K iCabove-mentioned scope is met and Li with the degree of depth D of compressive stress layers 2when the amount of O is 0.1 ~ 1 % by mole, glass substrate reliably has the physical strength being suitable for disk.Below to destruction toughness value K iCbe described with the degree of depth D of compressive stress layers.
(destroy toughness value K iC)
Destroy toughness value K iC[MPam 1/2] obtain in the following manner: with load p [N], the sharp-pointed adamas casting die (Vickers casting die) of known Vickers is given as security into glass substrate, make to form impression and crackle at glass substrate.If the Young modulus of setting glass substrate is E [Pa], setting impression catercorner length is d [m], and half length of setting surface crack is a [m], then broken bad Tough value K iC[MPam 1/2] can represent with following formula.
K IC＝0.026·E 1/2·P 1/2·(d/2)/a 3/2
In addition, only otherwise special instruction, broken bad Tough value K iCrepresent that load p is measured as the Po Huai Tough value of 9.81N (1000gf).Above-mentioned destruction toughness value changes with glass ingredient, but also change according to chemical intensified condition, therefore in order to obtain by the glass substrate for disc after chemical enhanced, can, according to adjustment of formula and chemical intensification treatment condition, above-mentioned destruction toughness value can be made to be the scope expected.
(compressive stress layers)
Fig. 3 illustrates the compressive stress layers of glass substrate 10 and the figure of tension stress layer.
Because the glass substrate of present embodiment 10 is chemical enhanced, the surface 12 of the first type surface therefore in the both sides of glass substrate 10 is formed with compressive stress layers 14, is formed with tension stress layer 16 in the inside of glass substrate 10 in the mode clipped by the compressive stress layers 14 of both sides.This compressive stress layers 14 and tension stress layer 16 are by carrying out chemical enhanced to glass substrate 10 and being formed.
In general, if the glass-impregnated forming glass substrate is carried out chemical enhanced in the mixed melting salt of sodium salt and sylvite, Li ion then in glass and the Na ion in fuse salt carry out ion-exchange, Na ion in addition in glass and the K ion in fuse salt carry out ion-exchange, thus be formed with compressive stress layers near surface, be formed with tension stress layer at inside glass.But, because the glass substrate of present embodiment 10 uses as glass ingredient only containing the Li of less than 1 % by mole 2the glass of O, therefore the degree of depth D of compressive stress layers 14 is less, and the maximal value of compression stress is high.In general, employing containing the Li more than 1 % by mole 2in the glass substrate of the glass of O, the Li ion in glass and the Na ion in fuse salt carry out ion-exchange, and the Na ion in glass and the K ion in fuse salt carry out ion-exchange, form stable stress distribution thus.But, as the glass substrate 10 of present embodiment, at Li 2in the glass that the containing ratio of O is lower, only comprise the Na in a little and fuse salt +ion carries out the Li ion of ion-exchange.On the other hand, the Na ion in glass and the K ion in fuse salt carry out ion-exchange.Because the ion that in glass, ionic radius is large, the rate of propagation of alkaline metal ions is less, and the K ion therefore entered in glass by ion-exchange is not spread and rests on the surface 12 of glass in glass.Therefore, only containing the Li of less than 1 % by mole 2the degree of depth D of the compressive stress layers 14 of the glass substrate 10 of O is more shallow.Such compressive stress layers generally can be measured by Babinet method.But in the glass substrate 10 of present embodiment, because the degree of depth D of compressive stress layers 14 is more shallow, the maximal value of compression stress is very big on the other hand, is therefore difficult to measure this value.
Because at Li 2the containing ratio of O is difficult to when extremely low obtain chemical enhanced effect, therefore Li 2the lower limit of the containing ratio of O is % by mole to represent being 0.1%.Li 2the preferred scope of the containing ratio of O is % by mole to represent being 0.1% ~ 0.6%.
In the glass substrate 10 of present embodiment, the degree of depth D of above-mentioned compressive stress layers 14 meets D>=57K iC -1.6, and D>=20 [μm].
Define like this and destroy toughness value K iCcan be made by the manufacture method of disk glass blank (glassblank) described later with the glass substrate 10 of the degree of depth D of compressive stress layers 14.
From the intensity this point guaranteeing glass substrate 10, the thickness of slab of the glass substrate 10 of present embodiment is preferably 0.3 ~ 1.5mm.Thickness of slab is more preferably more than 0.5mm.
(test of the physical strength of glass substrate and evaluation)
Contact with rotary main shaft when glass substrate 10 is assembled into hard disk drive and be fixed, therefore the inner side end of glass substrate 10 easily produces damage.And, before being fixed in rotary main shaft, carry out the inching of the position of glass substrate.In addition, in order to record servo track before being assembled into hard disk drive, the inner side end of glass substrate 10 is fixed on fixture.Now, the inner side end of glass substrate 10 easily produces damage.Such damage makes physical strength (bending strength) decline.
Fig. 4 is the figure of the test method that physical strength (bending strength) is described.In the test of physical strength (bending strength), the steel ball 18 that mounting is larger than the diameter of this circular hole on the circular hole that the center of glass substrate 10 is empty, obtains the minimum load load that glass substrate 10 breaks when applying load to steel ball 18 downwards.Glass substrate is evaluated according to this minimum load load.About the test of such physical strength (bending strength), after glass substrate to be configured at the position of regulation by the inner side end of glass substrate 10 in advance through rotary main shaft, carry out carrying out after the process of extracting from rotary main shaft and scar apply process.Apply process by this scar, glass substrate 10 reappears the state of the glass substrate as described above when being assembled into hard disk drive.
As applied destruction toughness value K before treatment from the above-mentioned scar showing glass substrate iCand learn like that in Fig. 2 of the corresponding relation between physical strength (bending strength), when inner side end does not damage completely glass substrate 10, destroy toughness value K iCmore corresponding with physical strength (bending strength).Wherein, produce at inner side end in the glass substrate 10 of damage, destroy toughness value K iCdecline with the corresponding relation of physical strength (bending strength).
Therefore, in the present embodiment, above-mentioned scar is being carried out and is applying the evaluation of physical strength of the laggard oozy glass substrate of process.
The glass substrate 10 of the multiple conditions made by carrying out various change to the condition of glass ingredient and chemical intensification treatment is carried out to the evaluation of the physical strength (bending strength) of such glass substrate.The bending strength of glass substrate when working as the evaluation carrying out above-mentioned physical strength (bending strength) is met the condition of more than 60N and the qualification rate that is judged as the glass substrate of certified products is that the condition setting of more than 95% is as the condition reliably with the physical strength being suitable for disk, when above-mentioned qualification rate is less than 95%, be set as having the condition of the physical strength being unsuitable for disk, multiple condition is distinguished.Fig. 5 is the figure of the result that above-mentioned differentiation is shown, is to illustrate that the qualification rate relevant to physical strength (bending strength) is the figure of the scope of the glass substrate 10 of more than 95%.In Figure 5, at Li 2o containing in the glass substrate of the glass ingredient of promising less than 1 % by mole, the scope of hatched example areas to be qualification rate the be glass substrate of more than 95%, that is, be the scope of the glass substrate reliably with the physical strength (bending strength) being suitable for disk.This hatched example areas destroys toughness value K iC1 [MPam 1/2] more than, the degree of depth D of compressive stress layers 14 meets D>=57K iC -1.6, and the region of D>=20 [μm].That is, the destruction toughness value K of glass substrate iC[MPam 1/2] be 1 [MPam 1/2] more than, to be provided with based on chemical enhanced compressive stress layers and the degree of depth D [μm] of compressive stress layers meets D>=57K at glass baseplate surface iC -1.6, and the glass substrate of D>=20 [μm] becomes the glass substrate with the physical strength being suitable for disk.More preferably toughness value K is destroyed iC[MPam 1/2] be 1.2 [MPam 1/2] more than, the degree of depth D of compressive stress layers meets D>=70K iC -1.6and D>=35 [μm].
About the glass ingredient of such glass substrate 10, work as Li 2when O is 0.1 ~ 1 % by mole, uses in the fuse salt of chemical intensification treatment and comprise KNO 3and NaNO 3salt-mixture can suitably be formed based on chemical enhanced compressive stress layers, be preferred in this.
(chemical intensification treatment)
Chemical intensification treatment be impregnated in high-temperature fusion salt by glass substrate, makes the process of the ion in fuse salt and the ion-exchange in glass.From guaranteeing above-mentioned physical strength this point, fuse salt preferably comprises the KNO of 55% ~ 85% mass percent 3.In this case, NaNO 3containing ratio be preferably 15% ~ 45% mass percent.More preferably the KNO in fuse salt 3containing ratio be 60% ~ 80% mass percent, NaNO 3containing ratio be 20% ~ 40% mass percent.By making KNO 3containing ratio be more than 75% mass percent, destroy toughness value K iCuprise.Especially preferred, the KNO in fuse salt 3containing ratio be 75% ~ 85% mass percent, NaNO 3containing ratio be 15% ~ 25% mass percent.
The processing time that impregnated in fuse salt in chemical enhanced needs the temperature according to fuse salt and suitably adjusts, and be preferably more than 2 hours in the scope of 400 ~ 600 DEG C, form darker compressive stress layers 14 is more than 4 hours.But, if impregnated in fuse salt for a long time, produce stress and relax and cause destroying toughness value K iCdecline, in addition, the chemical enhanced processing time is elongated, is more preferably therefore less than 20 hours by the processing time that glass substrate 10 impregnated in fuse salt.From the above point of view, 4 ~ 16 hours are more preferably.Although as the Li in glass substrate 2o amount is difficult to when being 0.1 ~ 1 % by mole obtain chemical enhanced effect, but by carrying out chemical intensification treatment through the longer time, K in higher temperatures like this iCmeet above-mentioned scope with compression stress layer depth D and the higher glass substrate of permanance when producing damage can be formed.If the Li in glass substrate 2o amount is more, then the Li's in the glass substrate exchanged with the K in fuse salt in chemical intensification treatment is many containing quantitative change.And in the present embodiment, carry out long chemical intensification treatment like that due to as described above, therefore K ion replaces Li ion easily to enter the inside of glass substrate deeper.Therefore, although the thickness of the compressive stress layers formed by chemical intensification treatment is thickening, the stress value on the surface of compressive stress layers easily relaxes, and sometimes can not make K iCimprove.Therefore, the Li in glass substrate 2o amount is less than 1 % by mole.
In addition, the treatment temperature of the fuse salt in chemical enhanced is preferably more than 400 DEG C, will obtain K at short notice iCwith the degree of depth D of compressive stress layers 14, be more preferably more than 450 DEG C.On the other hand, if treatment temperature is too high, for the nitrates decompose of chemical intensification treatment, be therefore preferably less than 570 DEG C.The treatment temperature of fuse salt such as 400 ~ 570 DEG C, more preferably carry out in the scope of 450 ~ 550 DEG C.
In addition, from suppressing the processing time of chemical intensification treatment to become the long point exceeding needs, toughness value K is destroyed iC[MPam 1/2] be preferably 2.5 [MPam 1/2] below.Due to same reason, degree of depth D is preferably less than 150 μm.
In addition, impregnated in after fuse salt reaches the stipulated time, when making the temperature of glass substrate turn back to room temperature, from making destruction toughness value K iCbe in above-mentioned scope this point with degree of depth D to set out, preferably until the temperature of glass substrate at least becomes during 200 DEG C, cool with the cooling velocity slowly of less than 30 DEG C per minute.In addition, if above-mentioned cooling velocity is too fast, sometimes the easy end at glass substrate produces and small collapses broken or crackle, and physical strength declines, and therefore above-mentioned cooling velocity is preferably until the temperature of glass substrate during at least becoming 200 DEG C less than 30 DEG C per minute.
The glass substrate 10 of present embodiment is made to meet above-mentioned destruction toughness value K iCthe scope of value and the degree of depth D of compressive stress layers 14 meets above-mentioned scope, as long as suitably adjustment glass ingredient and chemical intensification treatment condition (component of fuse salt, processing time, treatment temperature, cooling velocity).
(glass ingredient)
The glass ingredient of the glass substrate 10 of present embodiment such as can enumerate following alumina silicate glass.That is, % by mole to represent, glass substrate 10 comprises the SiO of 55% ~ 78% 2, 0.1% ~ 1% Li 2o, 2% ~ 15% Na 2mgO, CaO, SrO and BaO of O and total 10% ~ 25%.
The amount of CaO is less than 0.20 relative to the mol ratio CaO/ (MgO+CaO+SrO+BaO) of the total amount of MgO, CaO, SrO and BaO.By making mol ratio CaO/ (MgO+CaO+SrO+BaO) be less than 0.20, the decline of above-mentioned physical strength can be suppressed.Less than 0.18 is preferably by making mol ratio CaO/ (MgO+CaO+SrO+BaO), be more preferably less than 0.16, be particularly preferably less than 0.15, the efficiency (being difficult to produce the deterioration of fuse salt) and the maintenance physical strength that maintain ion-exchange can be realized.Especially, on (being difficult to produce the deterioration of the fuse salt) point of efficiency maintaining ion-exchange, glass substrate is preferably formed with the alumina silicate glass not comprising Ca.In addition, amorphous aluminum silicate glass is more preferably from the view point of reducing surfaceness or easily carrying out chemical enhanced, above-mentioned glass.
(size of glass substrate)
The size of glass substrate 10 does not limit especially, and thickness of slab is such as 0.3 ~ 1.5mm.Glass substrate 10 such as has for nominal diameter the diameter of the disk being 2.5 inches, 1 inch, 1.8 inches, 3 inches, 3.5 inches etc.
(manufacture method of glass substrate for disc)
Below the manufacture method of such glass substrate 10 is described.
First, carry out the forming processes of glass blank, this glass blank is the starting material of the glass substrate for disc of the tabular with a pair first type surface.Then, process cut by the corase grind carrying out this glass blank.Afterwards, shape processing process and end surface grinding process are implemented to glass blank.Afterwards, the glass substrate obtained from glass blank is employed to the fine lapping process of bonded-abrasive.Afterwards, the 1st milled processed, chemical intensification treatment and the 2nd milled processed are implemented to glass substrate.In addition, although carry out with above-mentioned flow process in the present embodiment, do not need to carry out all above-mentioned process, suitably can not carry out these process yet.Below each process is described.
The forming processes of (a) glass blank
Glass blank shaping in can use such as compression forming method.Circular glass blank can be obtained by compression forming method.And, known manufacture method such as glass tube down-drawing, again daraf(reciprocal of farad), fusion method etc. can be used to manufacture glass blank.By carrying out suitable shape processing to the plate glass blank made with these known manufacture methods, the discoideus glass blank of the raw material as glass substrate for disc can be obtained.
B process cut by () corase grind
Cut in process at corase grind, specifically, glass blank is remained on be arranged at holding member (bearing) retaining hole in and carry out the grinding of the first type surface of glass blank both sides, this holding member (bearing) is installed on known double-side grinding apparatus.Such as free abrasive can be used as abrasive substance.Cut in process at corase grind, carry out grinding to make glass blank approximately as the thickness of slab size of target and the flatness of first type surface.In addition, cut process about corase grind, carry out according to the dimensional accuracy of the glass blank after shaping or surfaceness, according to circumstances also can not carry out.
(c) shape processing process
Then, shape processing process is carried out.In shape processing process, by using known job operation to form circular hole after the forming processes of glass blank, obtain the glass substrate vacating the disc-shape of circular hole thus.Afterwards, the chamfering (り is got in face) of the end face of glass substrate is implemented.Thus, the end face of glass substrate is formed with the dip plane (sandwiched face) of the side wall surface vertical with first type surface and connection side wall and first type surface.
The process of (d) end surface grinding
Then the end surface grinding process of glass substrate is carried out.End surface grinding process comprises the lapping liquid of free abrasive to supply between abrasive brush and the end face of glass substrate and makes the end face relative movement of abrasive brush and glass substrate, carries out the process of grinding thus.In end surface grinding, using the inner side end of glass substrate and end face outside as grinding object, inner side end and end face outside is made to become mirror status.
(e) fine lapping process
Then, the first type surface in the both sides of glass substrate implements fine lapping process.Specifically, known double-side grinding apparatus is used to carry out grinding to the first type surface of glass substrate.Such as, bonded-abrasive is arranged at platform and carrys out grinding glass substrate.Specifically, being held in by glass substrate in retaining hole and carrying out the grinding of the first type surface of the both sides of glass substrate, this retaining hole is arranged at the bearing of the holding member as double-side grinding apparatus.
Although in the grinding process of present embodiment, make the major surface contacts of the grinding face and glass substrate comprising bonded-abrasive carry out the first type surface of grinding glass substrate, also can carry out the grinding employing free abrasive.
(f) the 1st milled processed
Then, the first type surface in the both sides of glass substrate implements the 1st milled processed.Specifically, the grinding of the first type surface of the both sides of glass substrate 10 is carried out in the retaining hole outer circumference side edge face of glass substrate being held in the bearing being arranged at lapping device.1st milled processed uses free abrasive, uses the polishing pad being pasted on platform.The thickness of slab of the 1st grinding adjustment glass substrate 10, and the crackle or the distortion that residue in first type surface is such as removed when carrying out the grinding based on bonded-abrasive.In the 1st grinding, can prevent the shape of first type surface end from excessively subsideing or give prominence to, and reducing the surfaceness such as arithmetic average roughness Ra of first type surface.
Free abrasive for the 1st grinding does not limit especially, such as, can use cerium oxide abrasive particle or zirconia grain etc.
The kind of polishing pad does not limit especially, such as, can use hard foam polyurethane resin finish machine.
(g) chemical intensification treatment
Then, fuse salt is used to implement above-mentioned chemical intensification treatment to glass substrate.As fuse salt, such as, can use and the potpourri of potassium nitrate, sodium nitrate is carried out heating the fuse salt obtained.In addition, potassium nitrate or sodium nitrate can be used alone.And, by glass substrate be impregnated in fuse salt, be present in Li ion in the glass ingredient on the top layer of glass substrate 10 or Na ion and be replaced as the relatively large Na ion of ionic radius in respective chemical enhanced liquid or K ion respectively, thus being formed with compressive stress layers on the surface of glass substrate 10, glass substrate 10 is reinforced.
The opportunity of carrying out chemical intensification treatment can suitably be determined, if but carry out milled processed after chemical intensification treatment, then can making surface smoothing and remove the foreign matter anchoring at glass baseplate surface because of chemical intensification treatment, is therefore particularly preferably.
H () the 2nd grinds (mirror ultrafinish) process
Then, the glass substrate after chemical intensification treatment is implemented the 2nd grinding.2nd grinding is for the purpose of the mirror ultrafinish of first type surface.Also known two sides lapping device is used in the 2nd grinding.Like this, can prevent the shape of the end of the first type surface of glass substrate 10 from exceedingly subsideing or give prominence to, and reducing the roughness of first type surface.2nd milled processed is different in free abrasive this point from the 1st milled processed, and in addition, the particle size of the free abrasive used in the 2nd milled processed is less compared with the particle size of the 1st milled processed.And the hardness of the resin finish machine of the polishing pad preferably used in the 2nd milled processed is lower compared with the hardness of the resin finish machine of the polishing pad for the 1st milled processed.
That is, by the 2nd grinding, polishing pad 10 easily sinks by pressure during grinding.
As the free abrasive for the 2nd milled processed, such as, can use the particulate of cataloid etc.In order to not make the effect of compressive stress layers when being formed at chemical intensification treatment disappear, the process redundancy of the 2nd milled processed is converted into thickness of slab and is preferably less than 2 μm.By cleaning polished glass substrate, glass substrate for disc can be obtained.Like this, the glass substrate 10 being implemented the 2nd milled processed becomes glass substrate for disc.
[test example]
In order to investigate the effect of present embodiment, according to becoming the mode formulate glass raw material of above-mentioned glass ingredient to make glass substrate, and carry out the chemical enhanced of glass substrate under various conditions.The glass ingredient of glass substrate is by the SiO of 65.5 % by mole 2, the Al of 5 % by mole 2o 3, the Li of 1 % by mole 2o, the Na of 9 % by mole 2o, the MgO of 16 % by mole, the ZrO of 3.5 % by mole 2as solvent.Now, in order to make Li 2o and Na 2the amount of O is constant namely become 10 % by mole and with 3 standard variable Li 2the containing ratio of O.Above-mentioned destruction toughness value K is measured to having carried out chemical enhanced glass substrate iC, also use known Babinet compensator method to measure the degree of depth D of compressive stress layers.In addition, the physical strength (bending strength [N]) of the glass substrate implementing above-mentioned scar applying process has been investigated with above-mentioned method.In the test of physical strength (bending strength), being investigated as tested object by 100 glass substrates processed under identical glass ingredient, identical chemical enhanced condition, is that the situation of more than 60N is as qualified qualification rate of trying to achieve glass substrate using bending strength.The condition of more than 95% that the qualification rate of glass substrate become is as the condition being suitable for disk.
By the Li in glass shown in following table 1 2the containing ratio of O, molten salt components (KNO 3, NaNO 3containing than), fuse salt temperature, chemical intensification treatment time carries out the destruction toughness value K of detailed, the glass substrate of the condition of various change iC, the degree of depth D of compressive stress layers, bending strength (mean value) and qualification rate.
[table 1]
By the result of above-mentioned table 1 using qualification rate be more than 95% condition summarize the region of the condition being suitable for this disk as the condition being suitable for disk, be the hatched example areas shown in Fig. 5.Zero mark in Fig. 5 represents that qualification rate is that more than 98%, △ mark represents that qualification rate is more than 95% and less than 98%, × mark represents that qualification rate is less than 95%.Therefore, zero mark and △ mark represent and are suitable for disk.It can thus be appreciated that, make containing with the Li % by mole representing 0.1% ~ 1% 2o reliably has as the glass substrate of glass ingredient the physical strength (bending strength) being suitable for disk, needs to destroy toughness value K iC1 [MPam 1/2] more than, and the degree of depth D of compressive stress layers 14 meets D>=57K iC -1.6, and D>=20 [μm].Preferred scope destroys toughness value K iC[MPam 1/2] be 1.2 [MPam 1/2] more than and the degree of depth D [μm] of compressive stress layers 14 meets D>=70K iC -1.6and the scope of D>=35 [μm].
In addition, at use removing Li 2o, Na 2the above-mentioned solvent of O, and establish Li 2the amount of O is 0 % by mole, Na 2the amount of O is the example of 10 % by mole and establishes Li 2the amount of O is 0.05 % by mole, Na 2when the amount of O is the example of 9.95 % by mole, degree of depth D is less than 5 μm, and qualification rate is all less than 95%.This reason is speculated as because Li 2the amount of O is very few, fail to carry out ion-exchange well in chemical intensification treatment.
In addition, at use removing Li 2o, Na 2the above-mentioned solvent of O, and establish Li 2the amount of O is 1.5 % by mole, establishes Na 2when the amount of O is 8.5 % by mole, vitrification point Tg is less than 650 DEG C.
Above, the glass substrate 10 of present embodiment is summarized,
(1) a kind ofly employ containing with the Li % by mole being expressed as 0.1 ~ 1% 2the glass substrate of the glass of O, it destroys toughness value K iC[MPam 1/2] be 1 [MPam 1/2] more than, and being provided with based on chemical enhanced compressive stress layers on glass baseplate surface, the degree of depth D [μm] of described compressive stress layers meets D>=57K iC -1.6, and D>=20 [μm], this glass substrate has higher vitrification point compared with glass substrate in the past, and reliably has the physical strength (bending strength) being suitable for disk.In addition, also known, in order to make destruction toughness value K iCmeet above-mentioned scope with the degree of depth D of compressive stress layers and reliably there is physical strength (bending strength), needing the Li containing 0.1 ~ 1% 2o.
(2) by making vitrification point become more than 650 DEG C, and can preferably use as the glass substrate for disc of power assist mode.
(3) amount employing CaO is a glass substrate for the glass of less than 0.20 relative to the mol ratio CaO/ (MgO+CaO+SrO+BaO) of the total amount of MgO, CaO, SrO and BaO, and this glass is % by mole to represent the SiO comprising 55 ~ 78% 2, 0.1% ~ 1% Li 2o, 2% ~ 15% Na 2mgO, CaO, SrO and BaO of O, total 10% ~ 25%, and the glass substrate employing the alumina silicate glass not comprising Ca can maintain samely chemical enhanced in the efficiency of ion-exchange, and physical strength same can be maintained.
(4) in chemical enhanced, when glass substrate be impregnated in KNO 3with NaNO 3mixed melting salt liquid in time, mixed melting salt is by comprising the KNO of 55% ~ 85% mass percent 3and the degree of depth D of above-mentioned compressive stress layers can be realized.
Above the manufacture method of glass substrate for disc of the present invention, glass substrate for disc and disk are explained, but the invention is not restricted to the above-described embodiment and examples, certainly can carry out various improvement or change without departing from the spirit and scope of the invention.
Label declaration
10: glass substrate for disc;
12: surface;
14: compressive stress layers;
16: tension stress layer;
18: steel ball.

Claims (9)

1. a glass substrate for disc, wherein,
This glass substrate for disc contains with the Li % by mole representing 0.1% ~ 1% 2o as glass ingredient,
Destroy toughness value K iC[MPam 1/2] be 1 [MPam 1/2] more than,
Be provided with based on chemical enhanced compressive stress layers at glass baseplate surface, the degree of depth D [μm] of described compressive stress layers meets D>=57K iC -1.6, and D>=20 [μm].
2. glass substrate for disc according to claim 1, wherein,
Vitrification point Tg is more than 650 DEG C.
3. the glass substrate for disc according to claims 1 or 2, wherein,
Described glass substrate for disc contains % by mole to represent,
The SiO of 55% ~ 78% 2,
The Li of 0.1% ~ 1% 2o,
The Na of 2% ~ 15% 2o, and
Add up to MgO, CaO, SrO and BaO of 10% ~ 25%, as glass ingredient,
The amount of CaO is less than 0.20 relative to the mol ratio (CaO/ (MgO+CaO+SrO+BaO)) of the total amount of MgO, CaO, SrO and BaO.
4. according to the glass substrate for disc in claims 1 to 3 described in any one, wherein,
As glass ingredient, be made up of the alumina silicate glass not comprising Ca.
5. a disk, wherein, this disk comprises
Glass substrate for disc described in any one in Claims 1 to 4 and
Be formed at the magnetosphere on the surface of described glass substrate.
6. a manufacture method for glass substrate for disc, wherein, the manufacture method of this glass substrate for disc comprises:
Make the process of glass substrate, wherein, this glass substrate is plate-like, containing with the Li % by mole representing 0.1% ~ 1% 2o, and
Carrying out chemical enhanced process, by implementing described chemical enhanced to described glass substrate, making to destroy toughness value K iC[MPam 1/2] be 1 [MPam 1/2] more than, by described chemical enhanced and the degree of depth D [μm] being arranged at the compressive stress layers of glass baseplate surface meets D>=57K iC -1.6, and D>=20 [μm].
7. the manufacture method of glass substrate for disc according to claim 6, wherein,
Described chemical enhanced process be impregnated in by described glass substrate to comprise KNO 3and NaNO 3mixed melting salt liquid in process, described mixed melting salt comprises the KNO of 55% ~ 85% mass percent 3.
8. the manufacture method of the glass substrate for disc according to claim 6 or 7, wherein,
Described glass substrate after described chemical treatment contains % by mole to represent,
The SiO of 55% ~ 78% 2,
The Li of 0.1% ~ 1% 2o,
The Na of 2% ~ 15% 2o, and
Add up to MgO, CaO, SrO and BaO of 10% ~ 25%, as glass ingredient,
The amount of CaO is less than 0.20 relative to the mol ratio (CaO/ (MgO+CaO+SrO+BaO)) of the total amount of MgO, CaO, SrO and BaO.
9. according to the manufacture method of the glass substrate for disc in claim 6 ~ 8 described in any one, wherein,
Described glass substrate is made up of the alumina silicate glass not comprising Ca.
CN201480042395.XA 2013-09-18 2014-09-18 Glass substrate for disc, the manufacturing method of glass substrate for disc and disk Active CN105431904B (en)

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CN102290056A (en) * 2007-09-28 2011-12-21 Hoya株式会社 Glass substrate for magnetic disk and manufacturing method of the same
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