CN105431904B - Glass substrate for disc, the manufacturing method of glass substrate for disc and disk - Google Patents

Abstract

Glass substrate for disc contain indicated with mole % 0.1%~1% Li₂O is as glass ingredient.The destruction toughness value K of the glass substrate_IC[MPa·m^1/2] it is 1 [MPam^1/2] more than.Glass baseplate surface is provided with the compressive stress layers based on chemical strengthening, the depth D [μm] of the compressive stress layers meets D >=57K_IC ^‑1.6And D >=20 [μm].The glass substrate obtains by adjusting the condition of chemical intensification treatment.

Description

Glass substrate for disc, the manufacturing method of glass substrate for disc and disk

Technical field

The present invention relates to glass substrate for disc, the manufacturing method of glass substrate for disc and disks.

Background technology

It is preferable to use glass substrates for the disk used in the past as one of information recording carrier.Currently, hard drive is answered The increased requirement of memory capacity in device, seeks the densification of magnetic recording.In recent years, in order to keep the magnetic recording of disk highly dense Degreeization, it is proposed that form the energy assisted magnetic recording of magnetospheric heat-assisted magnetic recording mode of iron-platinum etc. on the glass substrate The recording medium of mode.The glass substrate used in recording medium about the energy supplementary mode, when the magnetism for forming iron-platinum Glass substrate is exposed to 700 DEG C or so of high temperature when layer, therefore it is required that being maintained as the mechanical strength and glass of glass substrate It is higher to change temperature (ガ ラ ス translocation moves point temperature).

On the other hand, it is also known that there are implement on the glass substrate to improve mechanical strength chemical intensification treatment to Compressive stress layers are formed on glass substrate.The compression stress value of compressive stress layers or the depth of compressive stress layers are mended by Babinet Device method is repaid to acquire.It is also known that there are according to the depth of the compression stress value and compressive stress layers that are acquired using Babinet's compensator method come The side of the glass substrate for the attribute (profile) for having the compression stress or tensile stress suitable for glass substrate for disc is provided Method.For example, it is known that there is the following glass substrate for implementing chemical intensification treatment：In order to higher impact resistance, work as glass It is 49.1 μm or less and in the stress based on Babinet's compensator method that the most external stressor layers of the main surface of glass substrate, which are given as security into length, When setting that θ is in formed angle between the main surface and compression stress in attribute, the value y as defined in the θ is the most external stress Layer gives as security length or less (patent document 1).

In addition, there is known the data storage medium glass bases for stabilizing the two for taking into account excellent impact resistance and disk shape Plate and its manufacturing method.Specifically, the manufacturing method of the glass substrate includes that glass substrate is impregnated in mixed melting In salt, and the chemical intensification treatment engineering of compression layer is formed on the surface of the glass substrate and the back side.At this point, glass substrate Containing lithium ion as alkaline components, mixed melting salt contain sodium nitrate, potassium nitrate and is expressed as 1 with mass percent~ Glass substrate is impregnated in 325 DEG C or more 475 DEG C for the treatment of temperatures below 30 in mixed melting salt by 6% lithium nitrate Processing time below minute, and meet formula below.Wherein, T is treatment temperature (unit：K), t is that processing time is (single Position：Second).1900≤T×log(t2)≤2900.It is well known that in the glass substrate, setting is using based on JISR1607's The destruction toughness value that casting die plunging is measured from is 1.2 or more, can improve mechanical strength (patent document 2).

Existing technical literature

Patent document

Patent document 1：Japanese Unexamined Patent Publication 2009-099251 bulletins

Patent document 2：Japanese Unexamined Patent Publication 2011-134367 bulletins

Invention content

The subject that the invention solves

But in the glass material that the glass substrate for disc obtained with above-mentioned well known technology uses, usual vitreous Temperature is 600 DEG C hereinafter, therefore in the recording medium by previous glass substrate for disc for above-mentioned energy supplementary mode In the case of, it is exposed in above-mentioned high temperature and easy tos produce the warpage of substrate or isolate.Therefore, in the note of energy supplementary mode In the glass substrate of recording medium, even if mechanical strength at room temperature is higher can not to apply previous glass substrate.

Vitrification point is improved, there is known reduce Li₂The amount of O, but due in the glass for having used this glass In substrate, the amount of Li is less, therefore even if the liquid using the well known chemical strengthening fuse salt comprising Na or K etc. carries out Chemical treatment, can not also form the compressive stress layers for the degree that mechanical strength is increased to required by glass substrate for disc.

Therefore, the purpose of the present invention is to provide the glass substrate for disc reliably with the mechanical strength suitable for disk With the manufacturing method of glass substrate for disc and the disk of the glass substrate for disc is used.

Means for solving the problems

(mode 1)

One embodiment of the present invention is the glass substrate for disc such as lower structure.

The glass substrate for disc contain indicated with mole % 0.1%~1% Li₂O destroys toughness as glass ingredient Value K_IC[MPa·m^1/2] it is 1 [MPam^1/2] more than, glass baseplate surface is provided with the compressive stress layers based on chemical strengthening, The depth D [μm] of the compressive stress layers meets D >=57K_IC ^-1.6And D >=20 [μm].

Furthermore it is preferred that destroying toughness value K_IC[MPa·m^1/2] it is 2.5 [MPam^1/2] below.Additionally, it is preferred that depth D is 150 μm or less.

(mode 2)

In addition, according to the glass substrate for disc of mode 1, wherein the vitrification point Tg of the glass substrate for disc is 650 DEG C or more.

(mode 3)

In addition, the glass substrate for disc according to mode 1 or 2, wherein the glass substrate for disc contain with Mole % indicates, 55%~78% SiO₂, 0.1%~1% Li₂O, 2%~15% Na₂O, and total 10%~ 25% MgO, CaO, SrO and BaO, as glass ingredient, the conjunction of the amount of CaO relative to MgO, CaO, SrO and BaO The molar ratio (CaO/ (MgO+CaO+SrO+BaO)) for counting amount is 0.20 or less.

(mode 4)

According to the glass substrate for disc described in any one in mode 1~3, wherein the glass substrate for disc Plate thickness be 0.3~1.5mm.

At this point, making the glass substrate for disc be in the case of becoming the size of nominal 2.5 inches of sizes or more 0.5mm or more.

(mode 5)

According to the glass substrate for disc described in any one of mode 1~4, wherein as disk glass base The glass ingredient of plate is made of the alumina silicate glass not comprising Ca.

(mode 6)

A kind of disk, wherein the disk be included in mode 1~5 in any one described in glass substrate for disc, with And it is formed in the magnetosphere on the surface of the glass substrate.

(mode 7)

A kind of manufacturing method of glass substrate for disc, wherein the manufacturing method of the glass substrate for disc includes：It makes The processing of glass substrate, wherein the glass substrate is plate-like, contains the Li that 0.1%~1% is indicated with mole %₂O, Yi Jijin The processing of row chemical strengthening, by implementing the chemical strengthening to the glass substrate so that destroy toughness value K_IC[MPa·m^{1 /2}] it is 1 [MPam^1/2] more than, the depth D [μ of the compressive stress layers of glass baseplate surface are set to by the chemical strengthening M] meet D >=57K_IC ^-1.6And D >=20 [μm].

(mode 8)

The manufacturing method of glass substrate for disc according to mode 7, wherein in the processing of the chemical strengthening, It is that the glass substrate is impregnated in comprising KNO₃And NaNO₃Mixed melting salt liquid in processing, the mixed melting salt Include the KNO of 55%~85% mass percent₃。

(mode 9)

The manufacturing method of glass substrate for disc according to mode 7 or 8, it is preferred that after the chemical treatment The glass substrate contain and indicated with a mole %, 55%~78% SiO₂, 0.1%~1% Li₂O, 2%~15% Na₂O, and total 10%~25% MgO, CaO, SrO and BaO, as glass ingredient, the amount of CaO relative to The molar ratio CaO/ (MgO+CaO+SrO+BaO) of total amount of MgO, CaO, SrO and BaO is 0.20 or less.

(mode 10)

The manufacturing method of glass substrate for disc according to any one in mode 7~9, wherein the glass The plate thickness of substrate is 0.3~1.5mm.

At this point, the plate thickness is preferably 0.5mm or more.

(mode 11)

The manufacturing method of glass substrate for disc according to any one in mode 7~10, wherein the glass Substrate is made of the alumina silicate glass not comprising Ca.

Invention effect

According to above-mentioned mode, it is capable of providing the glass substrate for disc reliably with the mechanical strength suitable for disk.

Description of the drawings

Fig. 1 is the stereogram of the glass substrate for disc of present embodiment.

Fig. 2 be show glass substrate scar application processing before destruction toughness value and mechanical strength (bending strength) between Correspondence figure.

Fig. 3 is the compressive stress layers for the glass substrate for illustrating present embodiment and the figure of tension stress layer.

Fig. 4 is the figure for the test method for illustrating mechanical strength (bending strength).

Fig. 5 is the figure of the range for the glass substrate for showing present embodiment.

Specific implementation mode

The glass substrate for disc of present embodiment is described in detail below.

[glass substrate for disc]

Fig. 1 is the stereogram of the glass substrate for disc 10 (hereinafter referred to as " glass substrate 10 ") of present embodiment.Such as Fig. 1 Shown, glass substrate 10 is circular plate shape, is formed as the ring-type that central part is hollowed out concentric round.In glass substrate 10 In, at least surface of glass substrate is formed with compressive stress layers by chemical strengthening on the surface of glass plate 10.

For glass substrate 10, contain the Li that 0.1%~1% is indicated with mole %₂O is as glass ingredient.As The mechanical property of glass substrate 10 destroys toughness value K_IC[MPa·m^1/2] it is 1 [MPam^1/2] more than.In the table of glass substrate 10 Face is provided with the compressive stress layers based on chemical strengthening, and the depth D [μm] of the compressive stress layers meets D >=57K_IC ^-1.6And D ≥20[μm].More preferably meet and destroys toughness value K_IC[MPa·m^1/2] it is 1.2 [MPam^1/2] more than, the depth of compressive stress layers D [μm] is D >=70K_IC ^-1.6And D >=35 [μm].

The vitrification point Tg of the glass of such glass substrate 10 is preferably 650 DEG C or more.In this case, glass base Although plate 10 can be used in various glass substrate for disc, it is preferably able to the disk glass base for energy supplementary mode Plate.

Wherein, toughness value K is destroyed_IC[MPa·m^1/2] it is preferably 2.5 [MPam^1/2] below.In addition, depth D is preferably 150 μm or less.

When making disk using glass substrate 10, made by least forming a film magnetosphere in the main surface of glass substrate 10 Make disk.

Magnetosphere is for example comprising with the alloy of Fe and/or Co and Pt magnetic material as main component.With the magnetosphere Disk be preferred for the disk of energy supplementary mode.As with the alloy of Fe and/or Co and Pt magnetic material as main component Material, can enumerate Fe-Pt magnetic materials, Co-Pt magnetic materials or Fe-Co-Pt magnetic materials.

When forming above-mentioned magnetosphere, it is main to form a film with the alloy of Fe and/or Co and Pt in the main surface of glass substrate After the magnetic material of ingredient, made annealing treatment.Here, the film-forming temperature of above-mentioned magnetic material is more than under normal circumstances 500 DEG C of high temperature.And in order to keep these magnetic materials crystalline orientation after film forming consistent, in the temperature more than film-forming temperature It is lower to carry out above-mentioned annealing.Therefore, Fe-Pt magnetic materials, Co-Pt magnetic materials or Fe-Co-Pt systems are being used Magnetic material formed it is magnetospheric in the case of, glass substrate is exposed in above-mentioned high temperature.From with superior heat resistance this Point sets out, and the 10 preferred vitrification point of glass substrate of present embodiment is 650 DEG C or more.Vitrification point Tg preferred lower limits are 660 DEG C, lower limit further preferably is 665 DEG C, and preferred lower limit is 670 DEG C, and further preferred lower limit is 675 DEG C.But if mistake Degree ground improves vitrification point Tg, then aftermentioned chemical intensification treatment temperature is got higher, when chemical strengthening cause the pyrolysis of fuse salt and The surface of attack glass substrate, therefore the upper limit of vitrification point Tg is preferably set as 740 DEG C.In addition, vitrification point Tg is changing It learns and strengthens front and back substantial constant.Even if the glass substrate 10 being made of the glass of such vitrification point Tg is in glass substrate Magnetosphere and the progress of Fe-Pt magnetic material, Co-Pt magnetic materials or Fe-Co-Pt magnetic materials are formed on 10 After annealing, it may have higher flatness.

Keep the above-mentioned vitrification point Tg higher than previous, is realized by adjusting glass ingredient.Specifically, passing through inhibition The alkalinous metals such as Li, Na contain ingredient, can improve vitrification point Tg.

In this regard, the glass for the glass substrate of present embodiment 10 contains indicates 0.1%~1% with a mole % Li₂O。Li₂The containing ratio of O is preferably 0.1%~0.6%, more preferably 0.1%~0.3%.

The present application person is directed to the glass substrate of above-mentioned glass ingredient, is conceived to the change used in this manufacturing method Intensive treatment is learned, various researchs have been carried out to being formed to meet as compressive stress layers as the mechanical strength required by disk.

In general, as the mechanical strength of glass substrate for disc, well known bending strength is used.Disk glass base The bending strength of plate is to be worth as follows：It is placed on above-mentioned circular hole when by the steel ball bigger than the circular hole of the central opening in glass substrate And make to be worth determined by the load of breaking glass panel when gradually applying load to steel ball.It may be said that the examination of the bending strength Proved recipe method simulates the mechanical strength for the glass substrate for disc being fixed in the live spindle in hard disk drive.Another party Face will utilize always the destruction toughness value K measured by the casting die plunging based on JISR1607 in the past_IC[MPa·m^1/2] it is used as glass The index of the mechanical strength of glass substrate.

Fig. 2 be investigated in the new glass substrate made as glass substrate for disc, i.e. it is aftermentioned it is such It is upper on the glass substrate for the state that the inner side end of the circular of glass substrate and the peripheral portion of the circular hole do not damage It states and destroys toughness value K_IC[MPa·m^1/2] correspondence between the value of bending strength figure.It learns according to fig. 2, destroys toughness Value K_ICHigher, then bending strength is also substantially higher.But above-mentioned correspondence has been used such as lower glass substrate as a result, should Glass substrate when glass substrate is new product, in the main surface of the inner side end and glass substrate of the circular of glass substrate The peripheral portion of circular hole does not damage.Actual setting is in the inner side end and glass of the circular at the center of glass substrate for disc The peripheral portion of the circular hole of the main surface of glass substrate, before being fixed in the live spindle of hard disk drive, sometimes with Various parts contact and generate small damage.For example, when in order to be fixed on live spindle and simultaneously with live spindle self-contact When carrying out position adjustment to glass substrate, or when carrying out extracting inspection to glass substrate using touch sensor, glass The peripheral portion of the inner side end of the circular of substrate and the circular hole of main surface will produce damage sometimes.Particularly, based on In the next-generation magnetic recording of energy assisted magnetic recording mode, track density is high, therefore especially needed stringent progress disk is opposite In the positioning of main shaft to inhibit guiding error (tracking mistake).Moreover, being easy in glass when carrying out the adjustment operation The circular hole periphery of glass substrate generates damage.The inventors have found that since glass substrate as described above is by actual assembled to hard disk Damage caused by before driving device, sometimes correspondence as shown in Figure 2 may not be set up.In this case, Because the incidence (fraction defective) that bending strength declines is not in permissible range, therefore under the yield rate of glass substrate for disc Drop.Further, it was found that especially in Li₂In the lower glass substrate of amount of O, above-mentioned phenomenon can be significantly observed.

For the invalid of such a above-mentioned correspondence, the present application person judges, in addition to destroying toughness value K_ICIt Other indexs are also needed to outside.Therefore, to the glass ingredient of glass substrate and the chemically treated item implemented on the glass substrate Part has carried out various changes, and investigate due to the formation of the damage of the inner side end of glass substrate cause bending strength decline and As the fraction defective of the glass substrate for the defective work that can not be used as product offer, and conscientiously has studied and the fraction defective is applied The index of influence.

Its result thinks, though in order to obtain glass substrate being exposed in 700 DEG C or so of high temperature not warpage, It has carried out being assembled into the glass substrate that HDD is not also isolated after various adjustment, by Li₂The amount of O rubs for 0.1~1 The treatment conditions that chemical strengthening is adjusted in the glass substrate of your %, can reduce the fraction defective of glass substrate.And think, make Become in the glass substrate of certified products in the screening of the qualification rate (=1- fraction defectives) of glass substrate, destroys toughness value K_ICIt is 1[MPa·m^1/2] more than, and the depth of the compressive stress layers formed in glass surface by chemical strengthening be some steady state value with On, and need than according to destruction toughness value K_ICDetermining value is big.

That is, by Li₂The amount of O is the glass substrate 10 that few glass of 0.1~1 mole of % is constituted In, destroy toughness value K_IC[MPa·m^1/2] it is 1 [MPam^1/2] more than, it is provided with based on chemical strengthening in glass baseplate surface The depth D [μm] of compressive stress layers, compressive stress layers meets D >=57K_IC ^-1.6And D >=20 [μm].In this way, by providing glass The destruction toughness value K of substrate_ICWith the depth D of compressive stress layers, glass substrate reliably has the mechanical strength suitable for disk.Separately Outside, it is known that, as destruction toughness value K_ICMeet above range and Li with the depth D of compressive stress layers₂The amount of O is 0.1 When~1 mole of %, glass substrate reliably has the mechanical strength suitable for disk.Below to destroying toughness value K_ICAnd compression stress The depth D of layer is illustrated.

(destroy toughness value K_IC)

Destroy toughness value K_IC[MPa·m^1/2] obtain in the following manner：With load p [N] by well known Vickers Sharp diamond casting die (Vickers casting die) give as security into glass substrate, make to form impression and crackle in glass substrate.If setting glass The Young's modulus of glass substrate is E [Pa], sets impression catercorner length as d [m], sets half a length of a [m] of face crack, then Po Huai Tough values K_IC[MPa·m^1/2] being capable of following formula expression.

K_IC=0.026E^1/2·P^1/2·(d/2)/a^3/2

As long as in addition, not illustrating, bad Tough values K is broken_ICIndicate that load p is measured as the destruction of 9.81N (1000gf) Tough values.Above-mentioned destruction toughness value changes with glass ingredient, but also is changed according to chemical intensified condition, therefore in order to obtain It obtains by the glass substrate for disc after chemical strengthening, can be made above-mentioned according to adjustment of formula and chemical intensification treatment condition Destruction toughness value is desired range.

(compressive stress layers)

Fig. 3 is the figure of the compressive stress layers and tension stress layer that illustrate glass substrate 10.

Because the glass substrate 10 of present embodiment is by chemical strengthening, therefore in the main surface of the both sides of glass substrate 10 Surface 12 is formed with compressive stress layers 14, in the inside of glass substrate 10 in a manner of being clipped by the compressive stress layers 14 of both sides shape At there is tension stress layer 16.The compressive stress layers 14 and tension stress layer 16 pass through the shape to the progress chemical strengthening of glass substrate 10 At.

In general, if the glass-impregnated for constituting glass substrate is carried out chemistry in the mixed melting salt of sodium salt and sylvite Strengthen, then the Li ions in glass carry out ion exchange with the Na ions in fuse salt, in addition the Na ions in glass and melting K ions in salt carry out ion exchange, and to be formed about compressive stress layers on surface, being formed with stretching in inside glass answers Power layer.But because the glass substrate 10 of present embodiment is used as glass ingredient only contains 1 mole of % Li below₂O Glass, therefore the depth D of compressive stress layers 14 is smaller, and the maximum value of compression stress is high.In general, contain having used More than the Li of 1 mole of %₂In the glass substrate of the glass of O, the Li ions in glass carry out ion with the Na ions in fuse salt It exchanges, and the Na ions in glass carry out ion exchange with the K ions in fuse salt, and stable stress distribution is consequently formed. But as the glass substrate of present embodiment 10, in Li₂In the lower glass of containing ratio of O, only include a little with melting Na in salt⁺Ion carries out the Li ions of ion exchange.On the other hand, the K ions in the Na ions in glass and fuse salt into Row ion exchange.Because of the big ion of ionic radius in glass, the diffusion velocity of alkaline metal ions is smaller, therefore passes through The K ions that ion exchange enters in glass do not spread into glass and rest on the surface 12 of glass.Therefore, it only rubs containing 1 You are % Li below₂The depth D of the compressive stress layers 14 of the glass substrate 10 of O is shallower.Such compressive stress layers are generally possible to It is measured by Babinet method.But in the glass substrate of present embodiment 10, because the depth D of compressive stress layers 14 is shallower, The maximum value of another aspect compression stress is very big, and therefore, it is difficult to measure the value.

Because in Li₂It is difficult to obtain the effect of chemical strengthening, therefore Li in the case that the containing ratio of O is extremely low₂The containing ratio of O Lower limit indicate it is 0.1% with a mole %.Li₂The preferred range of the containing ratio of O indicates it is 0.1%~0.6% with a mole %.

In the glass substrate 10 of present embodiment, the depth D of above-mentioned compressive stress layers 14 meets D >=57K_IC ^-1.6And D≥20[μm]。

It defines like this and destroys toughness value K_ICGlass substrate 10 with the depth D of compressive stress layers 14 can be by aftermentioned Disk made of the manufacturing method of glass blank (glass blank).

From the intensity this point for ensuring glass substrate 10, the plate thickness of the glass substrate 10 of present embodiment is preferably 0.3~1.5mm.Plate thickness is more preferably 0.5mm or more.

(experiment and evaluation of the mechanical strength of glass substrate)

It contacts and is fixed with live spindle when glass substrate 10 is assembled into hard disk drive, therefore glass base The inner side end of plate 10 easy tos produce damage.Moreover, before being fixed in live spindle, the micro- of the position of glass substrate is carried out Adjustment.In addition, the inner side end of glass substrate 10 is consolidated in order to record servo track before being assembled into hard disk drive Due to fixture.At this point, the inner side end of glass substrate 10 easy tos produce damage.Such damage makes mechanical strength (bending strength) Decline.

Fig. 4 is the figure for the test method for illustrating mechanical strength (bending strength).In the experiment of mechanical strength (bending strength) In, the steel ball 18 bigger than the diameter of the circular hole is loaded on the empty circular hole in the center of glass substrate 10, when downwards to steel ball 18 apply the minimum load load that the rupture of glass substrate 10 is found out when load.Glass base is evaluated according to the minimum load load Plate.About the experiment of such mechanical strength (bending strength), live spindle is previously threaded through in the inner side end of glass substrate 10 After glass substrate is configured at defined position, the laggard of the i.e. scar application processing of the processing extracted from live spindle has been carried out Row.It is handled by the scar application, glass substrate 10 reappears the glass base when being assembled into hard disk drive as described above The state of plate.

Destruction toughness value K such as before showing the above-mentioned scar application processing of glass substrate_IC(bending resistance is strong with mechanical strength Degree) between correspondence Fig. 2 in learn it is such, glass substrate 10 that inner side end does not damage completely the case where Under, destroy toughness value K_ICIt is corresponded to compared with mechanical strength (bending strength).Wherein, the glass substrate of damage is generated in inner side end In 10, toughness value K is destroyed_ICDecline with the correspondence of mechanical strength (bending strength).

Therefore, in the present embodiment, the mechanical strength of glass substrate is carried out after carrying out above-mentioned scar application processing Evaluation.

Glass to the multiple conditions made by the condition to glass ingredient and chemical intensification treatment makes various changes Glass substrate 10 carries out the evaluation of the mechanical strength (bending strength) of such glass substrate.It is (anti-ought to carry out above-mentioned mechanical strength Curved intensity) evaluation when glass substrate bending strength meet the condition of 60N or more and be judged as the glass substrate of certified products Qualification rate be 95% or more condition setting as reliably have be suitable for disk mechanical strength condition, in above-mentioned qualification In the case that rate is less than 95%, it is set as, with the condition for the mechanical strength for being unsuitable for disk, distinguishing multiple conditions. Fig. 5 is the figure for the result for showing above-mentioned differentiation, is to show that with mechanical strength (bending strength) relevant qualification rate be 95% or more Glass substrate 10 range figure.In Figure 5, in Li₂O's contains the glass substrate for 1 mole of % glass ingredient below In, hatched example areas is the range for the glass substrate that qualification rate is 95% or more, that is, is reliably to have the machinery suitable for disk strong Spend the range of the glass substrate of (bending strength).The hatched example areas is to destroy toughness value K_ICIt is 1 [MPam^1/2] more than, compression answer The depth D of power layer 14 meets D >=57K_IC ^-1.6And the region of D >=20 [μm].That is, the destruction toughness value K of glass substrate_IC [MPa·m^1/2] it is 1 [MPam^1/2] more than, glass baseplate surface is provided with the compressive stress layers based on chemical strengthening and presses The depth D [μm] of stress under compression layer meets D >=57K_IC ^-1.6And the glass substrate of D >=20 [μm] becomes with the machine suitable for disk The glass substrate of tool intensity.More preferably destroy toughness value K_IC[MPa·m^1/2] it is 1.2 [MPam^1/2] more than, compressive stress layers Depth D meets D >=70K_IC ^-1.6And D >=35 [μm].

About the glass ingredient of such glass substrate 10, work as Li₂When O is 0.1~1 mole of %, in chemical intensification treatment Fuse salt in use include KNO₃And NaNO₃Salt-mixture can be properly formed the compressive stress layers based on chemical strengthening, It is on this point preferred.

(chemical intensification treatment)

Chemical intensification treatment is that glass substrate is impregnated in high-temperature fusion salt, is made in the ion and glass in fuse salt The processing of ion exchange.From ensuring that above-mentioned mechanical strength this point, fuse salt preferably comprises 55%~85% mass percentage The KNO of ratio₃.In this case, NaNO₃Containing ratio be preferably 15%~45% mass percent.In more preferable fuse salt KNO₃Containing ratio be 60%~80% mass percent, NaNO₃Containing ratio be 20%~40% mass percent.By making KNO₃Containing ratio be 75% mass percent or more, destroy toughness value K_ICIt gets higher.In particular it is preferred that the KNO in fuse salt₃ Containing ratio be 75%~85% mass percent, NaNO₃Containing ratio be 15%~25% mass percent.

The processing time being impregnated in fuse salt in chemical strengthening needs suitably to be adjusted according to the temperature of fuse salt, excellent It is 2 more than hour to be selected in 400~600 DEG C of range, and it is 4 more than hour for forming deeper compressive stress layers 14.But It is, if being impregnated in fuse salt for a long time, to generate stress and mitigate and cause to destroy toughness value K_ICDecline, in addition to this, chemical strengthening Processing time it is elongated, therefore it is 20 hours or less that glass substrate 10, which is more preferably impregnated in the processing time in fuse salt,. From the above point of view, more preferably 4~16 hours.Although the Li in glass substrate₂O amounts are 0.1~1 mole of % When be difficult to obtain the effect of chemical strengthening, but by carrying out at chemical strengthening in higher temperatures and by longer time like this Reason, K_ICMeet above range with compression stress layer depth D and the higher glass substrate of durability when generating damage can be formed. If the Li in glass substrate₂O amounts are more, then in the glass substrate exchanged with the K in fuse salt in chemical intensification treatment Li containing quantitative change it is more.Moreover, in the present embodiment, such carried out at prolonged chemical strengthening due to as described above Reason, therefore K ions replace Li ions to be easy the inside deeper into glass substrate.Therefore, although passing through chemical intensification treatment The thickness of the compressive stress layers of formation thickens, but the stress value on the surface of compressive stress layers is easy to mitigate, and cannot make K sometimes_IC It improves.Therefore, the Li in glass substrate₂O amounts are 1 mole of % or less.

In addition, the treatment temperature of the fuse salt in chemical strengthening is preferably 400 DEG C or more, K is obtained in a short time_ICWith The depth D of compressive stress layers 14, more preferably 450 DEG C or more.On the other hand, if treatment temperature is excessively high, it is used for chemical strengthening The nitrate of processing decomposes, therefore preferably 570 DEG C or less.The treatment temperature of fuse salt such as 400~570 DEG C, more preferably It is carried out in the range of 450~550 DEG C.

In addition, from inhibiting the processing time of chemical intensification treatment to become beyond the prolonged point needed, destroy tough Property value K_IC[MPa·m^1/2] it is preferably 2.5 [MPam^1/2] below.Due to same reason, depth D is preferably 150 μm or less.

In addition, after being impregnated in fuse salt and reaching the stipulated time, when making the temperature of glass substrate return to room temperature, from making Destroy toughness value K_ICIt is in above range this point with depth D to set out, preferably at least becomes 200 in the temperature until glass substrate During until DEG C, cooled down with 30 DEG C per minute slow cooling velocities below.In addition, if above-mentioned cooling velocity mistake Soon, it is sometimes easy to generate the small broken or crackle that collapses in the end of glass substrate, mechanical strength declines, therefore above-mentioned cooling speed Degree is preferably 30 DEG C per minute or less during until the temperature of glass substrate at least becomes 200 DEG C.

The glass substrate 10 of present embodiment is set to meet above-mentioned destruction toughness value K_ICValue range and compression stress Layer 14 depth D meet above range, 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 can for example enumerate alumina silicate glass below.That is, with Mole % indicates that glass substrate 10 includes 55%~78% SiO₂, 0.1%~1% Li₂O, 2%~15% Na₂O, with And total 10%~25% MgO, CaO, SrO and BaO.

Molar ratio CaO/ (MgO+CaO+ of the amount of CaO relative to total amount of MgO, CaO, SrO and BaO SrO+BaO it is) 0.20 or less.By making molar ratio CaO/ (MgO+CaO+SrO+BaO) for 0.20 hereinafter, above-mentioned machine can be inhibited The decline of tool intensity.By make molar ratio CaO/ (MgO+CaO+SrO+BaO) be preferably 0.18 hereinafter, more preferably 0.16 with Under, particularly preferably 0.15 hereinafter, can realize the efficiency (being difficult to generate the deterioration of fuse salt) for maintaining ion exchange and maintain Mechanical strength.Especially maintain ion exchange efficiency (being difficult to generate the deterioration of fuse salt) point on, glass substrate preferably with Alumina silicate glass not comprising Ca is constituted.In addition, from the viewpoint of reducing surface roughness or being easy to carry out chemical strengthening, Above-mentioned glass is more preferably amorphous aluminum silicate glass.

(size of glass substrate)

The size of glass substrate 10 is not limited especially, and plate thickness is, for example, 0.3~1.5mm.Glass substrate 10 for example has Be useful for nominal diameter be 2.5 inches, 1 inch, 1.8 inches, 3 inches, the diameter of 3.5 inches etc. of disk.

(manufacturing method of glass substrate for disc)

The manufacturing method of such glass substrate 10 is illustrated below.

First, the forming processes of glass blank are carried out, which is that the disk of the plate with a pair of of main surface is used The raw material of glass substrate.Then, the corase grinding for carrying out the glass blank cuts processing.Later, shape processing is implemented to glass blank Processing and end surface grinding processing.Later, the glass substrate obtained from glass blank is carried out that the thin of fixed abrasive grain has been used to grind Mill processing.Later, the 1st milled processed, chemical intensification treatment and the 2nd milled processed are implemented to glass substrate.Although in addition, It is carried out in the present embodiment with above-mentioned flow, but all above-mentioned processing need not be carried out, it can also be suitably without these Processing.Each processing is illustrated below.

(a) forming processes of glass blank

Such as compression forming methods can be used in the molding of glass blank.It can be obtained by compression forming methods circular Glass blank.Moreover, manufacturing method well known to glass tube down-drawing, again daraf(reciprocal of farad), fusion method etc. can be used to manufacture glass blank.By right Suitable shape processing is carried out with the plate glass blank that these well known manufacturing methods make, can be obtained as disk glass The disk-shaped glass blank of the raw material of substrate.

(b) corase grinding cuts processing

In corase grinding cuts processing, specifically, glass blank to be maintained to the retaining hole for being set to holding member (bearing) The grinding of main surface that is interior and carrying out glass blank both sides, the holding member (bearing) are installed on well known two sides grinding dress It sets.Such as free abrasive grain can be used as grinding-material.In corase grinding cuts processing, be ground so that glass blank substantially Close to as the plate thickness size of target and the flatness of main surface.In addition, processing is cut about corase grinding, according to glass billet after molding The dimensional accuracy or surface roughness of material carry out, and can not also according to circumstances carry out.

(c) shape processing is handled

Then, shape processing processing is carried out.In shape processing processing, by being used after the forming processes of glass blank Well known processing method forms circular hole, thus to obtain the glass substrate for the disc-shape for vacating circular hole.Later, implement glass substrate End face chamfering (face takes り).The side wall surface vertical with main surface is formed on the end face of glass substrate as a result, and is connect The inclined surface (sandwiched face) of side wall surface and main surface.

(d) end surface grinding is handled

Then the end surface grinding processing of glass substrate is carried out.End surface grinding processing is the end face to abrasive brush and glass substrate Between supply make comprising the lapping liquid of free abrasive grain the end face of abrasive brush and glass substrate relatively move, be thus ground Processing.In end surface grinding, using the inner side end of glass substrate and end face outside as grinding object, make inner side end and outside End face becomes mirror status.

(e) fine lapping is handled

Then, implement fine lapping processing in the main surface of the both sides of glass substrate.Specifically, being ground using well known two sides Turning device is ground the main surface of glass substrate.For example, fixed abrasive grain is set to platform to be ground glass substrate.Specifically Ground is said, glass substrate is held in retaining hole and is carried out the grinding of the main surface of the both sides of glass substrate, which sets It is placed in the bearing of the holding member as double-side grinding apparatus.

Although in the grinding processing of present embodiment, make the main surface of grinding surface and glass substrate comprising fixed abrasive grain It contacts to be ground the main surface of glass substrate, but can also carry out having used the grinding of free abrasive grain.

(f) the 1st milled processed

Then, implement the 1st milled processed in the main surface of the both sides of glass substrate.Specifically, by the outer of glass substrate All side end faces are held in the retaining hole for the bearing for being set to grinding device and carry out the main surface of the both sides of glass substrate 10 Grinding.1st milled processed uses free abrasive grain, uses the polishing pad for being pasted on platform.1st grinding adjustment glass substrate 10 Plate thickness, and crackle or the deformation for remaining on main surface are for example removed in the case where carrying out the grinding based on fixed abrasive grain. In 1st grinding, it can prevent the shape of main surface end from excessively subsideing or protruding, and reduce the surface roughness example of main surface Such as arithmetic average roughness Ra.

Free abrasive grain for the 1st grinding is not limited especially, such as can use cerium oxide abrasive grain or zirconium oxide Abrasive grain etc..

The type of polishing pad is not limited especially, such as can use hard foam polyurethane resin finish machine.

(g) chemical intensification treatment

Then, implement above-mentioned chemical intensification treatment to glass substrate using fuse salt.As fuse salt, such as can make With the fuse salt that the mixture of potassium nitrate, sodium nitrate is carried out to heating acquisition.In addition, potassium nitrate or nitric acid can be used alone Sodium.Moreover, by the way that glass substrate is impregnated in fuse salt, be present in Li in the glass ingredient on the surface layer of glass substrate 10 from The relatively large Na ions of ionic radius or K ions that son or Na ions are replaced as respectively in respective chemical strengthening liquid, to Compressive stress layers are formed on the surface of glass substrate 10, glass substrate 10 is reinforced.

Carrying out the opportunity of chemical intensification treatment can be suitably determined, but if being ground place after chemical intensification treatment Reason can then make smooth surface and remove the foreign matter for anchoring at glass baseplate surface because of chemical intensification treatment, therefore be special It is preferred that.

(h) the 2nd grinding (mirror ultrafinish) processing

Then, implement the 2nd grinding on the glass substrate after chemical intensification treatment.2nd grinding is ground with the minute surface of main surface For the purpose of mill.Well known two sides grinding device is also used in the 2nd grinding.In such manner, it is possible to prevent the main surface of glass substrate 10 The shape of end exceedingly subside or protrude, and reduce the roughness of main surface.At 2nd milled processed and the 1st grinding Reason is different on this point in free abrasive grain, in addition, the particle size of the free abrasive grain used in the 2nd milled processed is ground with the 1st The particle size of mill processing compares smaller.Also, it is preferred that the resin finish machine of the polishing pad used in the 2nd milled processed is hard Degree is lower compared with for the hardness of the resin finish machine of the polishing pad of the 1st milled processed.

That is, by the 2nd grinding, polishing pad 10 is easy to sink by pressure when grinding.

As the free abrasive grain for the 2nd milled processed, the particle of colloidal silicon dioxide etc. can be used for example.In order not to The effect of compressive stress layers when making to be formed in chemical intensification treatment disappears, and the allowance of the 2nd milled processed is converted into plate thickness Preferably 2 μm or less.By cleaning the glass substrate being ground, glass substrate for disc can be obtained.In this way, being carried out the 2nd The glass substrate 10 of milled processed becomes glass substrate for disc.

[test example]

In order to investigate the effect of present embodiment, glass raw material is prepared in the way of as above-mentioned glass ingredient to make Make glass substrate, and carries out the chemical strengthening of glass substrate under various conditions.The glass ingredient of glass substrate is rubbed 65.5 The SiO of your %₂, 5 moles of % Al₂O₃, 1 mole of % Li₂O, the Na of 9 moles of %₂O, the MgO of 16 moles of %, 3.5 moles of % ZrO₂As basic component.At this point, in order to make Li₂O and Na₂The amount of O is constant to be become 10 moles of % and is become with 3 standards Li is moved₂The containing ratio of O.Above-mentioned destruction toughness value K is measured the glass substrate for carrying out chemical strengthening_IC, also use known Babinet's compensator method measure the depth D of compressive stress layers.Above-mentioned wound is implemented in addition, having been investigated in above-mentioned method Trace applies the mechanical strength (bending strength [N]) of the glass substrate of processing.It, will be in the experiment of mechanical strength (bending strength) Processed 100 glass substrates are adjusted as test object under conditions of identical glass ingredient, identical chemical strengthening It looks into, bending strength is acquired into the qualification rate of glass substrate for the situation of 60N or more as qualified.By the qualification rate of glass substrate As 95% or more condition as suitable for disk condition.

It is shown in following table 1 by the Li in glass₂Containing ratio, the molten salt components (KNO of O₃、NaNO₃Containing than), Detailed, glass substrate the destruction toughness value K for the condition that fuse salt temperature, chemical intensification treatment time make various changes_IC, pressure Depth D, bending strength (average value) and the qualification rate of stress under compression layer.

【Table 1】

The result of above-mentioned table 1 is summarized using the condition that qualification rate is 95% or more as the condition suitable for disk suitable for being somebody's turn to do The region of the condition of disk is hatched example areas shown in fig. 5.Zero mark in Fig. 5 indicates that qualification rate is 98% or more, △ marks Indicate that qualification rate is 95% or more and less than 98%, × mark indicates that qualification rate is less than 95%.Therefore, zero mark and △ marks It indicates to be suitable for disk.It follows that make containing the Li for indicating 0.1%~1% with mole %₂Glass of the O as glass ingredient Substrate reliably has the mechanical strength (bending strength) suitable for disk, needs to destroy toughness value K_ICIt is 1 [MPam^1/2] more than, And the depth D of compressive stress layers 14 meets D >=57K_IC ^-1.6And D >=20 [μm].Preferred range is to destroy toughness value K_IC [MPa·m^1/2] it is 1.2 [MPam^1/2] more than and the depth D [μm] of compressive stress layers 14 meet D >=70K_IC ^-1.6And D >= The range of 35 [μm].

In addition, using removing Li₂O、Na₂The above-mentioned basic component of O, and set Li₂The amount of O is 0 mole of %, Na₂O Amount be the example of 10 moles of % and set Li₂The amount of O is 0.05 mole of %, Na₂The amount of O rubs for 9.95 In the case of the example of your %, depth D is 5 μm hereinafter, qualification rate is all less than 95%.The reason is speculated as because of Li₂O's contains Measure it is very few, fail in chemical intensification treatment to carry out ion exchange well.

In addition, using removing Li₂O、Na₂The above-mentioned basic component of O, and set Li₂The amount of O is 1.5 moles of %, sets Na₂In the case that the amount of O is 8.5 moles of %, vitrification point Tg is less than 650 DEG C.

More than, it summarizes to the glass substrate 10 of present embodiment,

(1) a kind of to have used containing the Li for being expressed as 0.1~1% with mole %₂The glass substrate of the glass of O destroys Toughness value K_IC[MPa·m^1/2] it is 1 [MPam^1/2] more than, and the pressure based on chemical strengthening is provided on glass baseplate surface The depth D [μm] of stress under compression layer, the compressive stress layers meets D >=57K_IC ^-1.6And D >=20 [μm], the glass substrate with Past glass substrate, which is compared, has higher vitrification point, and reliably has the mechanical strength (bending strength) suitable for disk. In addition, also knowing, in order to make destruction toughness value K_ICMeet above range with the depth D of compressive stress layers and reliably has Mechanical strength (bending strength), needs containing 0.1~1% Li₂O。

(2) by making vitrification point become 650 DEG C or more, and can be preferably as the disk glass of energy supplementary mode Substrate uses.

(3) a kind of molar ratio of having used the amount of CaO total amount relative to MgO, CaO, SrO and BaO CaO/ (MgO+CaO+SrO+BaO) is the glass substrate of 0.20 glass below, which indicates to include 55 with a mole %~ 78% SiO₂, 0.1%~1% Li₂O, 2%~15% Na₂O, add up to 10%~25% MgO, CaO, SrO and BaO, and used the glass substrate of the alumina silicate glass not comprising Ca that can maintain in chemical strengthening samely Ion exchange efficiency, and be able to maintain that mechanical strength same.

(4) in chemical strengthening, when glass substrate is impregnated in KNO₃With NaNO₃Mixed melting salt liquid in when, mix Fuse salt is closed by including the KNO of 55%~85% mass percent₃And it can realize the depth D of above-mentioned compressive stress layers.

The glass substrate for disc of the present invention, the manufacturing method of glass substrate for disc and disk have been carried out in detail above Carefully illustrate, but the present invention is not limited to the above-described embodiment and examples, it certainly can be in the model for the purport for not departing from the present invention Enclose the interior various modifications or changes of progress.

Label declaration

10：Glass substrate for disc；

12：Surface；

14：Compressive stress layers；

16：Tension stress layer；

18：Steel ball.

Claims (9)

1. a kind of glass substrate for disc, wherein

The glass substrate for disc contain indicated with mole % 0.1%~1% Li₂O as glass ingredient,

Destroy toughness value K_IC[MPa·m^1/2] it is 1 [MPam^1/2] more than,

Glass baseplate surface is provided with the compressive stress layers based on chemical strengthening, the depth D [μm] of the compressive stress layers is full Sufficient D >=57K_IC ^-1.6And D >=20 [μm],

The glass of the glass substrate for disc is amorphous aluminum silicate glass.

2. glass substrate for disc according to claim 1, wherein

Vitrification point Tg is 650 DEG C or more.

3. glass substrate for disc according to claim 1 or 2, wherein

The glass substrate for disc contains to be indicated with a mole %,

55%~78% SiO₂,

0.1%~1% Li₂O,

2%~15% Na₂O, and

Total 10%~25% MgO, CaO, SrO and BaO, as glass ingredient,

Molar ratio (CaO/ (MgO+CaO+SrO+ of the amount of CaO relative to total amount of MgO, CaO, SrO and BaO BaO it is)) 0.20 or less.

4. glass substrate for disc according to claim 1 or 2, wherein

As glass ingredient, it is made of the alumina silicate glass not comprising Ca.

5. a kind of disk, wherein the disk includes

Glass substrate for disc described in any one in Claims 1 to 4 and

It is formed in the magnetosphere on the surface of the glass substrate.

6. a kind of manufacturing method of glass substrate for disc, wherein the manufacturing method of the glass substrate for disc includes：

Make the processing of glass substrate, wherein the glass substrate is plate-like, contains the Li that 0.1%~1% is indicated with mole %₂O, The glass of the glass substrate is amorphous aluminum silicate glass, and

The processing for carrying out chemical strengthening, by implementing the chemical strengthening to the glass substrate so that destroy toughness value K_IC [MPa·m^1/2] it is 1 [MPam^1/2] more than, the compressive stress layers of glass baseplate surface are set to by the chemical strengthening Depth D [μm] meet D >=57K_IC ^-1.6And D >=20 [μm].

7. the manufacturing method of glass substrate for disc according to claim 6, wherein

The processing of the chemical strengthening is that the glass substrate is impregnated in comprising KNO₃And NaNO₃Mixed melting salt liquid In processing, the mixed melting salt includes the KNO of 55%~85% mass percent₃。

8. the manufacturing method of the glass substrate for disc according to claim 6 or 7, wherein

Treated that the glass substrate contains is indicated with a mole % for the chemical strengthening,

55%~78% SiO₂,

0.1%~1% Li₂O,

2%~15% Na₂O, and

Total 10%~25% MgO, CaO, SrO and BaO, as glass ingredient,

Molar ratio (CaO/ (MgO+CaO+SrO+ of the amount of CaO relative to total amount of MgO, CaO, SrO and BaO BaO it is)) 0.20 or less.

9. the manufacturing method of the glass substrate for disc described according to claim 6 or 7, wherein

The glass substrate is made of the alumina silicate glass not comprising Ca.