U.S. patent application number 10/794295 was filed with the patent office on 2004-09-30 for glass cutting method.
Invention is credited to Nishiyama, Tomohiro.
Application Number | 20040187659 10/794295 |
Document ID | / |
Family ID | 32993012 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040187659 |
Kind Code |
A1 |
Nishiyama, Tomohiro |
September 30, 2004 |
Glass cutting method
Abstract
This invention provides a method of cutting a glass substrate to
form a plurality of flat panel displays. The method includes
forming a scribe line or a line of weakness on a surface of a
mother material; treating the mother material with chemical to
further weaken the mother material; and cutting the mother
material. The scribe line may be formed using a masking technique.
The mother material may be treated with chemical by putting the
mother material into a chemical solution. Alternatively, the
chemical may be sprayed, blown, or exposed to the mother material.
The cutting of the mother material may be done by applying
mechanical and/or thermal stress along the scribe line.
Inventors: |
Nishiyama, Tomohiro; (Osaka,
JP) |
Correspondence
Address: |
Sung I. Oh, Esq.
Squire, Sanders & Dempsey, LLP
810 S. Figueroa Street, 14th Floor
Los Angeles
CA
90017
US
|
Family ID: |
32993012 |
Appl. No.: |
10/794295 |
Filed: |
March 4, 2004 |
Current U.S.
Class: |
83/13 |
Current CPC
Class: |
C03B 33/091 20130101;
C03B 33/033 20130101; C03B 33/07 20130101; C03B 33/074 20130101;
Y10T 83/04 20150401; C03C 15/00 20130101; C03C 2218/31 20130101;
G02F 1/133351 20130101; C03B 33/09 20130101 |
Class at
Publication: |
083/013 |
International
Class: |
B26D 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2003 |
JP |
2003-079675 |
Sep 22, 2003 |
JP |
2003-329865 |
Claims
What is claimed is:
1. A method for cutting glass, the method comprising: forming a
scribe line on a glass surface; and treating the glass surface with
a chemical to weaken the glass surface along the scribe line.
2. The method according to claim 1, further including: separating
the glass surface along the scribe line.
3. The method according to claim 1, further including: masking
along the glass surface to form the scribe line.
4. The method according to claim 3, where the masking includes a
screen printing method.
5. The method according to claim 3, where the masking includes an
aminated film processing method.
6. The method according to claim 3, where the masking includes a
resist applied photolithographic method.
7. The method according to claim 3, where the scribe line defines a
cutting pattern.
8. The method according to claim 1, where the treating includes
applying the chemical to the glass surface.
9. The method according to claim 1, further including providing the
chemical in a solution form and where the treating includes
immersing the glass surface into the chemical solution.
10. The method according to claim 9, further including: generating
bubbles within the chemical solution.
11. The method according to claim 10, further including: generating
a jet stream within the chemical solution.
12. The method according to claim 9, further including: moving the
chemical solution along the glass surface to cause the chemical
solution to flow into the scribe line along the glass surface.
13. The method according to claim 1, further including providing
the chemical in a solution form and where the treating includes
spraying the chemical solution onto the glass surface.
14. The method according to claim 1, further including providing
the chemical in a solution form and where the treating includes
blowing vapor of the chemical solution onto the glass surface.
15. The method according to claim 1, further including providing
the chemical in a solution form and where the treating includes
exposing the chemical solution onto the glass surface.
16. The method according to claim 1, further including: cutting the
glass surface along the scribe line.
17. The method according to claim 16, where the cutting includes
applying mechanical stress to the scribe line.
18. The method according to claim 17, where the glass surface has
first side with the scribe line and a second side that is opposite
of the first side, and where the applying mechanical stress
includes applying pressure to at least one of the sides of the
glass surface.
19. The method according to claim 16, where the cutting includes
applying thermal stress to the scribe line.
20. The method according to claim 19, where the applying thermal
stress includes applying laser light to the scribe line and cooling
the glass surface along the scribe line.
21. The method according to claim 16, where the scribe line defines
at least two portions of the glass surface, and where the cutting
includes applying tension along the scribe line to pull away the at
least two portions away from each other.
22. The method according to claim 21, where the portion of the
glass surface forms a flat panel display.
23. A method of forming a plat panel display, the method
comprising: masking a scribe line on a surface of a mother
material; treating the scribe line with chemical to weaken the
mother material along the scribe line; and cutting along the scribe
line.
24. The method according to claim 23, where the treating includes
agitating the chemical along the mother material.
25. The method according to claim 23, where the cutting includes
applying mechanical stress on the scribe line.
26. The method according to claim 23, where the cutting includes
applying thermal stress on the scribe line.
27. A method of forming a plurality of flat panel displays, the
method comprising: masking a plurality of scribe lines on a surface
of a mother material defining a plurality of portions; treating the
plurality of scribe lines with chemical to weaken the mother
material along the plurality of scribe lines; and cutting along the
plurality of scribe lines to form the plurality of portions each
defining a flat panel display.
28. The method according to claim 27, where the treating includes
agitating the chemical along the mother material.
29. The method according to claim 27, where the cutting includes
applying mechanical stress on the scribe line.
30. The method according to claim 27, where the cutting includes
applying thermal stress on the scribe line.
Description
RELATED APPLICATIONS
[0001] This application claims priority to two Japanese
applications: (1) 2003-079675 filed Mar. 24, 2003; and (2)
2003-329865 filed Sep. 22, 2003, which are both incorporated by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to a method of cutting glass and,
particularly, to a method of a cutting glass plate.
BACKGROUND OF THE INVENTION
[0003] A glass substrate used in fabrication of a flat panel
display such as a liquid crystal display, a plasma display or an
electroluminescence display is manufactured from a glass plate
larger in size than the glass substrate as a raw material
(hereinafter, such a glass plate will be referred to as "mother
material"). The glass substrate is manufactured by means of a
method of cutting a mother material. For example, as for a glass
substrate for a liquid crystal display used in a 15 inch monitor,
as described in FIG. 1, four pieces of the substrate are obtained
from a mother material of 550 mm.times.650 mm in size. Glass
substrates can be obtained by cutting one mother material. In such
a case, a glass plate on a surface of which a film is formed is
used as a mother material and glass substrates can be obtained by
cutting it.
[0004] On the other hand, in a case where a glass substrate for use
in a small liquid crystal display is manufactured, it is an
important cutting method of directly cutting a glass substrate
obtained by adhesion. The reason therefor is that the glass
substrate for use in a liquid crystal display is of a structure in
which two sub-glass substrates are adhered to each other with a
sealing agent. The glass substrate for used in a liquid crystal
here has cells 1 in which a liquid crystal is sealed between the
two sub-glass substrates.
[0005] Cutting of a mother material is disclosed in the following
non-patent literatures: Yasuaki Miyake, "Scribe and Brake
Technique", Monthly FPD Intelligence, a special number entitled LCD
Fabrication and Inspection Technique in the 4th generation,
published by Press Journal Inc. on Jan. 20, 2000, pp 85-89)
(hereinafter referred to as "non-patent literature 1"); and Takeshi
Yamamoto, "Light Beam Orientation Device Capable of Use in Clean
Room and Laser Glass Cutting Device," Monthly FPD Intelligence
1994. 4," published by Press Journal Inc., pp 28-31) (hereinafter,
referred to as "non-patent literature 2"). The cutting of a mother
material disclosed in the non-patent literatures 1 and 2 includes:
a scribing step of forming a scribe line on a surface of the mother
material; and a step of applying a mechanical or thermal stress on
the scribe line. This cutting method is called a scribe and brake
method.
[0006] A cutting method described in the non-patent literature 1 is
a general scribe and brake method. This scribe and brake method
includes a scribe line forming step and a mechanical stress
applying step. The scribe line forming step is a step of scratching
a mother material surface with a diamond or sintered carbide wheel
cutter to form a scribe line. A depth of a scribe line formed in
this step is a value of the order in the range of from 10 to 15% of
the thickness of a mother material. A mechanical stress applying
step is a step of applying a mechanical stress on a site where a
scribe line is formed. In this step, glass substrates are cut from
the mother material.
[0007] A cutting method described in the non-patent literature 2
includes a scribe line forming step and a thermal stress applying
step. This cutting method is a method adopted in a glass cutting
apparatus from ACCUDYNE Co. in USA. The scribe line forming step
includes the sub-steps of: (1) forming a small physical damage at
an end of a mother material with a metal foil; (2) illuminating the
physical damage with a linear laser beam; and (3) spraying a mixed
gas of helium and water onto the mother material immediately after
the illumination with the laser beam to rapidly cool it. In the
scribe line forming step, a scribe line on a molecular level is
formed in the mother material. The thermal stress applying step is
a step of illuminating both sides of a scribe line with laser
light, followed by spraying the mixture of helium and water onto
the scribe line to thereby cool it. By laser beam illumination and
cooling immediately thereafter, a thermal stress arises at the
scribed line to cut a glass substrate from the mother material.
[0008] In the cutting method described in the non-patent literature
1, however, the following problems have remained unsolved. A first
problem is that cracks occur in a mother material surface and in
the vicinity of the mother material surface in formation of a
scribe line. The cracks easily lead to glass cullet both in
scribing and cutting. A second problem is that a number of cracks
occur at an intersection between scribe lines in formation of the
scribe lines. Breakage of a mother material occurs in cutting
because of the presence of the cracks with ease. The glass
substrates obtained by cutting are weak in edge strength thereof
because of the presence of the cracks. A third problem is that, in
order to improve an edge strength of a glass substrate, it is
required to chamfer a glass substrate. In order to remove glass
powder and the like accompanied by chamfering, a necessity arises
for cleaning. That is, the cutting method is problematic because of
a low productivity as a cutting method of a glass substrate.
[0009] On the other hand, the cutting method described in the
non-patent literature 2 has been expected to have an effect of
being unnecessary for a clean process or a chamfering process after
the cutting, therefore with a high productivity. A problem has been
still remained, however, in the cutting method because of a low
cutting precision and a reduced speed in cutting process. Moreover,
a cutting apparatus from ACCUDYNE Co. disclosed in the non-patent
literature 2 is expensive, therefore, the apparatus cannot be
widely proliferated in general use.
[0010] It has been understood that glass breakage occurs from a
fine physical damage originally present on a mother material
surface. Therefore, with reduction in surface physical damage on a
surface of the glass substrate itself, it contributes to more
improvement on glass strength and more prevention of glass
breakage. In a case where a polishing process is applied that
removes a physical damage on a surface of the glass substrate, it
lowers productivity in cutting of a glass substrate. On the other
hand, if reduction can be achieved in physical damage on a glass
surface during the cutting process of a mother material, the
productivity in cutting of a glass substrate may be improved.
Therefore, there is a need for reducing a physical damage on a
mother material surface during the cutting process.
SUMMARY OF THE INVENTION
[0011] This invention provides a glass cutting method in which it
is suppressed to generate glass cullet and cracks in glass to
thereby achieve a glass substrate with a high dimensional
precision. That is, this invention provides a glass cutting method
capable of removing plane cracks in formation of a scribe line, or
to provide a glass cutting method in which formation of a scribe
line can be achieved without generating cracks. This may be
accompanied by a glass cutting method where a scribe line is formed
on a glass surface, followed by a chemical treatment.
[0012] This invention also provides a glass cutting method where
the masking step corresponding to a cutting pattern is performed on
a glass surface thereto, thereafter, performing a chemical
treatment thereon and to form a slit corresponding to the cutting
pattern thereon. According to this cutting method in which masking
is performed, a slit corresponding to a scribe line (hereinafter,
simply referred to as "slit") can be formed.
[0013] In situations where a mother material is cut by applying a
mechanical stress or a thermal stress thereto, a stress is
concentrated at a scribe line or a slit (hereinafter, collectively
referred to as "scribe line or the like"). As a result, it can be
suppressed to generate glass cullet and glass breakage in
cutting.
[0014] With this invention, there is less of necessity for a
cutting face treatment step after the cutting. This means that the
cutting of a glass substrate is performed at a low cost. This also
means that productivity in glass cutting is improved. Since
physical damages on a surface of a mother material on which no
masking is applied are reduced by a chemical treatment, a strength
of a glass substrate can be raised.
[0015] In a case of a cutting method in which a slit is formed,
this invention minimizes the chance that an external stress may be
applied on a mother material. Therefore, it minimizes risk of
generating cracks and breakage in glass in formation of the slit.
Since it is possible to form a slit in many shapes, a glass
substrate with a high dimensional precision is provided.
[0016] For example, the method of performing the masking include a
screen printing method, a laminate film processing method, a resist
applied photolithographic method and the like. Masking may be
performed by using a masking material with a chemical resistance to
a chemical treatment solution. The chemical treatment may be
performed by contact of a chemical treatment solution with a glass
surface. Glass may be immersed in a chemical treatment
solution.
[0017] In a case where a mother material is immersed in a chemical
treatment solution in the chemical treatment, it may generate
bubbles or a jet stream in the chemical treatment solution. In the
cases, an effect can be achieved that the chemical treatment
solution is agitated. In a case where bubbles are generated, it can
be prevented that a product produced in the chemical treatment
solution is prevented from being attached onto glass.
[0018] In the chemical treatment, the chemical treatment solution
preferably moves along a glass surface. For example, by causing the
bubbles and the jet stream to move along the glass surface, the
chemical treatment solution can also be moved along the glass
surface. In this case, an effect is great that physical damages
present on a mother material are reduced.
[0019] The chemical treatment may also be used to cause a chemical
treatment solution to flow into a portion in which a scribe line or
the like is formed. For example, by causing the bubbles and the jet
stream to flow into a portion in which a scribe line or the like is
formed, the chemical treatment solution can be caused to flow into
the portion in which a scribe line or the like is formed. In a case
where the chemical treatment solution is caused to flow into a
portion in which a scribe line or the like is formed, an action is
great that deepens a depth of the scribe line or the like.
[0020] The chemical treatment may be a treatment in which a
chemical treatment solution is sprayed onto a glass surface, a
vapor of the chemical treatment solution is blown onto a glass
surface, or a glass surface is exposed to a vapor of the chemical
treatment solution. After the chemical treatment ends, a mechanical
or thermal stress may be applied onto a scribe line or the like to
cut the glass. To cut the glass by applying the mechanical stress,
the glass may be cut in such a manner that a tension is applied in
a direction moving away glass portions from each other with a
scribe line or the like as a center. Alternatively, a pressure may
be applied either in a direction facing a glass surface on which a
scribe line or the like is formed or in a direction facing the
other surface opposite the surface on which the scribe line or the
like is formed to thereby apply a mechanical stress onto a scribe
line or the like and to cut glass. To apply a pressure on the
surface on which a scribe line or the like is formed is preferred
to the other way. In order to cut glass by applying the thermal
stress, it is preferable that after the chemical treatment ends,
both sides of a scribe line or the like are illuminated with laser
light to thereby cut glass.
[0021] The invention minimizes cracks from forming in glass caused
by cutting of a glass substrate. As a result, a dimensional
precision of a glass substrate for a liquid crystal display can be
raised. Furthermore, by decreasing physical damages on a glass
surface on which no masking is performed, a strength of a glass
substrate can be improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 shows a glass plate from which four glass substrates
for a liquid crystal display can be obtained;
[0023] FIG. 2 is a view illustrating a pressure cutting step of the
invention;
[0024] FIG. 3 is a schematic view obtained when a surface contour
of a glass substrate obtained by means of a cutting method of the
invention is observed with a microscope of a magnification of
.times.50;
[0025] FIG. 4 is a schematic view obtained when a surface contour
of a glass substrate obtained by cutting without performing a
chemical treatment after formation of a scribe line is observed
with a microscope of a magnification of .times.50;
[0026] FIG. 5 is a schematic view obtained when a cutting face
topograph of a glass substrate obtained by means of a cutting
method of the invention is observed with a microscope of a
magnification of .times.50;
[0027] FIG. 6 is a schematic view obtained when a cutting face
topograph of a glass substrate obtained by cutting without
performing a chemical treatment after formation of a scribe line is
observed with a microscope of a magnification of .times.50;
[0028] FIG. 7 schematically shows a glass plate strength measuring
method; and
[0029] FIG. 8 is a schematic view obtained when an adhered glass
substrate cut by means of a cutting method of the invention is
observed from a side thereof with a microscope of a magnification
of .times.50.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Hereinafter, description will be given of embodiments of a
cutting method of the invention. A glass cutting method of the
invention includes the steps of: forming a scribe line on a surface
of a mother material; performing a chemical treatment; and cutting
the mother material. A cutting method of the invention may also
replace the scribe line forming step and the chemical treatment
step with a slit forming step. The slit forming step may be
implemented in a procedure in which masking corresponding to a
cutting pattern is performed onto a mother material surface,
followed by a chemical treatment.
[0031] One sheet of a glass substrate is used as glass that can be
cut by means of a method of the invention. In a case where a liquid
crystal display glass substrate is manufactured, a mother material
may be adopted that is obtained by adhering two glass substrates to
each other with a sealing agent. The adhered glass substrate
usually includes a color filter layer or the like necessary for a
liquid crystal display glass substrate.
[0032] A scribe line on a surface of a mother material, similarly
to a conventional technique, can be formed with a diamond cutter or
a sintered carbide wheel cutter. A scribe line is formed by
scribing a line on a mother material with a diamond cutter or a
sintered carbide wheel cutter.
[0033] A scribe line can be formed by means of the same method as
that adopted by a cutting apparatus from ACCUDYNE Co. having been
employed a conventional technique. That is, (1) a physical damage
is formed at an edge of a mother material with a metal foil or the
like, (2) the physical damage is illuminated with a linear laser
beam and (3) immediately thereafter, a mixed gas of helium and
water is blown to the mother material to rapidly cool it. With the
three steps applied, a scribe line can be formed on a surface of a
mother material.
[0034] A slit on a surface of a mother material is formed by
performing masking on a surface of the mother material, followed by
a chemical treatment. The masking is implemented with a masking
material so as to correspond to a cutting pattern. A masking
material is preferably not corroded by a chemical treatment
solution. Examples of methods of applying the masking include a
screen printing method, a laminate film processing method, a resist
applied photolithographic method and the like.
[0035] The screen printing method is a method in which a screen
having portions some of which a masking agent passes through and
the other of which no masking agent passes through is brought into
contact with a surface of a mother material to extrude the masking
material through the some portions and to apply masking on the
glass surface. The laminate film processing method is a method in
which a film on one surface of which a pressure sensitive adhesive
layer is formed is used as a masking material, which is adhered to
the surface of a mother material. The resist applied
photolithographic method is a method in which masking is
implemented by applying a photoresist as a masking material on a
surface of a mother material, followed by illumination with
light.
[0036] In a case where a scribe line or the like is formed on one
sub-substrate of an adhered glass substrate, a scribe line of the
like is usually formed on the other sub-substrate usually directly
below the scribe line on the one sub-substrate. In a case where the
scribe line on the other sub-substrate can not be formed directly
below, a cut face of the adhered glass substrate takes a stepwise
profile in the thickness direction. With this stepwise profile, the
lower step of the profile can work as an adhering fixing portion to
another member.
[0037] A chemical treatment is effected by contact of a chemical
treatment solution with a glass as a mother material. The chemical
treatment solution may be a solution containing a chemical
dissolving glass. The chemical treatment solution is preferably an
aqueous solution containing hydrofluoric acid. The hydrofluoric
acid aqueous solution preferably contains one or more kind selected
from the group consisting of hydrofluoride, an inorganic acid and
an organic acid.
[0038] Examples of hydrofluorides include ammonium fluoride,
potassium fluoride and sodium fluoride. Examples of inorganic acids
include hydrochloric acid, sulfuric acid, phosphoric acid and
nitric acid. Examples of organic acids include acetic acid and
succinic acid. One or more kind of an anionic surfactant and an
ampholytic surfactant may be added to a chemical treatment
solution. A sulfonate type surfactant and the like are used as an
anionic surfactant. An amine type surfactant, for example, is used
as an ampholytic surfactant.
[0039] Main actions of each of the chemicals in chemical treatment
solutions are as follows. Hydrofluoric acid and hydrofluoride work
so as to etch off glass chemically. An inorganic acid, an organic
acid, an anionic surfactant and an ampholytic surfactant work so as
to prevent a product occurring in a chemical treatment solution
from being attached onto a glass surface.
[0040] A time for which a mother material is in contact with a
chemical treatment solution and a chemical treatment solution
temperature are properly altered according to a composition of a
mother glass and a thickness thereof.
[0041] Methods of bringing a chemical treatment solution into
contact with a mother material include the following (1) to (4)
methods, for example,
[0042] (1) immersion of a mother material in a chemical treatment
solution,
[0043] (2) spraying a chemical treatment solution onto a mother
material,
[0044] (3) blowing a vapor of a chemical treatment solution onto a
mother material, and
[0045] (4) a mother material being exposed to a vapor of a chemical
treatment solution.
[0046] In a case where a mother material is immersed in a chemical
treatment solution, it is preferable to generate bubbles or a jet
stream of the chemical treatment solution therein. In order to
generate bubbles or a jet stream of the chemical treatment
solution, it is recommended to install a bubble generator or a jet
device for the chemical treatment solution at the bottom of a
chemical treatment solution reservoir. In this case, it is possible
to attain an effect of agitating the chemical treatment solution.
In a case where a bubble generator is installed, a product in the
chemical treatment solution is raised to the surface thereof,
thereby enabling the product to be prevented from being attached
onto glass.
[0047] A bubble stream and a jet stream are the same as a stream of
the chemical treatment solution. Since a physical damage on a glass
surface is a recess, the chemical treatment solution therein is
hard to be exposed to the stream of the chemical treatment
solution. Therefore, the chemical treatment solution in the recess
comes into a stationary state to thereby slow an etching reaction
velocity there with ease. As a result, portions other than recesses
are etched off ahead thereof, there arises an effect to reduce
physical damages on a glass surface. Therefore, by moving the
chemical treatment solution along the glass surface, a great effect
can be achieved that reduces physical damages on a glass surface.
As a motion of the chemical treatment solution nears a motion
substantially in parallel to a glass surface, a more effect of
reducing physical damages is assured.
[0048] Furthermore, an effect arises that a corner of a glass
substrate is chamfered. This effect is achieved in company with a
chemical treatment. In a case where the chemical treatment solution
flows substantially in parallel to the glass surface, an effect of
chamfering the corner of a glass substrate is especially grows
large.
[0049] On the other hand, in case where the chemical treatment
solution is caused to flow into a portion in which a scribe line or
the like is formed, the chemical treatment solution in the portion
in which a scribe line or the like is formed enters a moving state
to thereby increase an etching reaction velocity; therefore, an
action increase that deepens a depth of a scribe line or the like.
In a case where the chemical treatment solution is caused to flow
into a scribe line or the like along a direction substantially
normal to a glass surface, more of the action is achieved that
deepens a depth of a scribe line or the like. In a case where the
chemical treatment solution is caused to flow into a scribe line or
the like as well, an effect arises that chamfers a corner of a
glass substrate.
[0050] In a case where a bubble generator or a chemical treatment
solution jet device is installed at the bottom of a chemical
treatment solution reservoir, a method of immersing a mother
material in a chemical treatment solution is selected from the
following viewpoint.
[0051] In a case where it is desired to increase an effect of
decreasing physical damages on a glass surface, a mother glass
substrate is lowered into the chemical treatment solution in a
direction normal to a surface of the solution. In a case where it
is desired to increase an effect to deepen a depth of a scribe line
or the like, a mother glass plate is immersed in the chemical
treatment solution in parallel to the surface thereof. The mother
material may be immersed in the chemical treatment solution
obliquely relative to the surface of the solution.
[0052] After a chemical treatment ends, a mother material is cut.
As a cutting method, it is recommended to cut glass applying a
mechanical or thermal stress thereonto. Methods of cutting by a
mechanical stress include a method of cutting by an applied tension
or pressurization. A method of cutting glass by a tension is a
method in which a tension is applied in a direction moving away
glass portions from each other with a scribe line or the like as a
center. On the other hand, a pressurizing method is a method by
applying a pressure at a scribe line or the like to thereby cut
glass. The pressurizing method is a preferable as a cutting
method.
[0053] In a case of a pressurizing method, a pressure may be
applied either in a direction facing a surface on which a scribe
line or the like is formed or a direction facing the other surface
opposite the surface on which a scribe line or the like is formed.
It is preferable to apply a pressure on the surface on which a
scribe line or the like is formed. FIG. 2 shows an example of a
state where a pressure is applied on the surface on which a scribe
line or the like is formed. The mother material 2 is bridged
between two rest tables 4. Then, a pressure tool 5 works so as to
apply a pressure to the scribe line or the like 3 from right
thereabove to enable a mother material to be cut.
[0054] In a case where a pressure is applied on a surface on which
a scribe line or the like is formed to cut a mother material, the
mother material can be cut with a pressure smaller than on the
other surface opposite the surface on which a scribe line or the
like is formed. A mother material with a shallower scribe line or
the like thereon can be cut while sustaining a smoothness on a cut
face. For example, in a case where a chemical treatment is applied
onto an aluminoborosilicate glass on which a slit of 200 .mu.m in
depth is formed, and of 40 mm.times.60 mm.times.0.7 mm in size to
cut it, it has been confirmed that a pressure of 3000 g or more is
necessary when a pressure is applied on the other surface opposite
the surface on which a slit is formed. On the other hand, it has
been confirmed that glass is cut with a pressure in the range of
1500 or more and 2000 g or less when a pressure is applied on the
surface on which a slit is formed.
[0055] That is, since only a smaller pressure is required, quick
cutting can be realized. Since there is a small chance that a
pressure is distributed to portions other than the scribe line, it
can be prevented to generate cracks of glass in cutting. Note that
a pressure tool brought into contact with glass may be a flat
plate. A thinner plate is preferably used.
[0056] As a method of applying a thermal stress, there has been
available, for example, a method in which both sides of a scribe
line or the like are illuminated with laser light to thereby cut
glass. In this case, laser heating is effected at a temperature of
glass melting temperature or lower.
[0057] The following examples illustrate the application of the
invention. It should be noted that the present invention is not
limited to the following examples.
EXAMPLE 1
[0058] Two liquid crystal display glass sheets of 400 mm.times.500
mm.times.0.7 mm in size were adhered to each other with a sealing
agent. Scribe lines of about 0.05 mm in depth were formed on both
surfaces thereof with a diamond cutter. One scribe line was formed
so as to be directly below the other scribe line. Then, a thickness
of the adhered glass was reduced in a chemical treatment by a
thickness of the order of 0.4 mm.
[0059] A chemical treatment was conducted in the following
conditions:
[0060] (1) A chemical treatment solution was an aqueous solution
containing 5% hydrofluoric acid, 10% hydrochloric acid and 5%
nitric acid;
[0061] (2) The adhered glass was immersed in the chemical treatment
solution with the glass oriented in a direction normal to a surface
of the solution;
[0062] (3) Bubbles were generated from the bottom of a chemical
treatment solution reservoir, wherein bubbles flew substantially in
parallel to a glass surface; and
[0063] (4) After the chemical treatment ended, a pressure was
applied at a scribe line from directly above to cut the adhered
glass.
COMPARATIVE EXAMPLE 1
[0064] Adhered glass was cut without applying a chemical treatment
thereto. The cutting was conducted in a similar manner to that in
Example 1 except that no chemical treatment was applied.
[0065] Observation was conducted on the glass substrates obtained
in Example 1 and Comparative Example 1 under a microscope. FIGS. 3
and 4 are schematic views obtained by observation on shapes of
corners of glass substrates in the neighborhood of intersections of
scribe lines. FIG. 5 and 6 are schematic views obtained by
observation on cutting face topographs of glass plates. FIGS. 3 and
5 are observation on a glass substrate applied with the chemical
treatment (Example 1). FIGS. 4 and 6 are observation on a glass
substrate not applied with the chemical treatment (Comparative
Example 1).
[0066] In FIGS. 3 and 4, portions in black are glass substrates 3.
The corner shape of the glass substrate 6 shown in FIG. 3 is not in
a broken glass state altogether. On the other hand, the corner
shape of the glass substrate 7 shown in FIG. 4 is recognized to
have glass breakage 8. From the observation, it is found that no
glass breakage is recognized at a corner of the glass substrate of
Example 1 to which the chemical treatment was applied. On the other
hand, it is found that glass breakage is recognized at a corner of
the glass substrate of Comparative Example 1 in which no chemical
treatment was applied. Consequently, it has been recognized that in
cutting a glass substrate, cracking of a glass substrate is
prevented by applying a chemical treatment thereto.
[0067] In FIG. 5, a glass cutting face 9 is smooth. On the other
hand, in FIG. 6, a glass cutting face 11 is not smooth, but has
cracks 13 thereon. In FIG. 5, a scribe line 10 on a glass surface
is linear. On the other hand, in FIG. 6, depressed recesses are
shown in black. That is, a scribe line 12 takes an irregular shape
with exaggerated depressions and projections. This exaggeration in
depression and projections show that glass cracking and breakage
occurred in cutting of the glass substrate. Therefore, it has been
confirmed that by performing a chemical treatment, glass cracks
generated in formation of a scribe line is removed.
[0068] It has been confirmed that in the glass sheet of Example 1,
a corner shape of a portion in which a scribe line is formed is
chamfered. On the other hand, it has been confirmed that in the
glass substrate of Comparative Example 1, a corner shape of a
portion in which a scribe line is formed is at a right angle or an
acute angle (not shown).
[0069] Strengths of the glass substrates of Example 1 and
Comparative Example 1 were measured. The measurement on a glass
substrate strength was performed in the following conditions. FIG.
7 shows a measuring method.
[0070] (1) Two glass sheet rest tables 15 of 40 mm (L2).times.40 mm
(L3).times.8.4 mm (L4) in size were installed in parallel to each
other with a spacing (L1) of 49 mm;
[0071] (2) a specimen glass sheet 14 was placed on the rest tables
15;
[0072] (3) a pressure is applied at a center line of the specimen
glass sheet from directly thereabove with a stainless pressure tool
16 of 50 mm (L5).times.2.0 mm (L6).times.10 mm (L7)) in size and a
speed of the pressure tool was 0.5 mm/min;
[0073] (4) the maximum pressure was measured when the specimen was
broken; and
[0074] (5) the maximum pressure was defined as a strength of the
glass substrate.
[0075] A strength of the glass substrate of Example 1 was 1500 g.
On the other hand, a strength of the glass substrate of Comparative
Example 1 was 1 g. That is, it is found that a glass substrate
strength is increased.
EXAMPLE 2
[0076] Two liquid crystal display glass sheets of 400 mm.times.500
mm.times.0.7 mm in size were adhered to each other with a sealing
agent. Masking was applied on both surfaces and a side surface of
the adhered glass. A laminate film was used in masking. Then the
laminate film used in the masking was peeled off as a band with a
width of 0.2 mm. The peeled portion is a portion in which a slit is
formed. The peeling-off of the laminate film was performed on both
surfaces of the adhered glass. The peeling-off of the laminate film
on the lower surface of the adhered glass was performed directly
below the portion on the upper surface thereof in which the peeling
off of the laminate film was performed.
[0077] Then a chemical treatment was performed. A chemical
treatment solution and conditions for bubble generation in the
chemical treatment solution were similar to those in Example 1.
Immersion of the adhered glass in the chemical treatment solution
was performed so that the surface of the chemical treatment
solution and a surface of the adhered glass were in parallel to
each other. That is, the adhered glass was lowered into the
solution so that bubbles impinge on the adhered glass along a
vertical direction. The chemical treatment was performed till a
slit of 0.05 mm in depth was formed.
[0078] Thereafter, a pressure was applied to cut the adhered glass.
Observation was conducted under a microscope on the glass substrate
obtained according to the above procedures. As a result, it was
confirmed that no cracking occurred on the end surface of the glass
substrate. It was furthermore confirmed that a cutting face was
smooth.
[0079] A strength of the glass substrate obtained in Example 2 was
performed by the same method as in Example 1. A glass substrate
strength was 1500 g.
EXAMPLE 3
[0080] A glass substrate was cut by means of a method different
from that of Example 2 only in respect of a peeling method of a
laminate film. The peeling-off of the laminate films on the upper
surface and the lower surface of the adhered glass substrate was in
parallel to each other. In addition, the peeling-off of the
laminate films on the upper surface and the lower surface of the
adhered glass substrate was performed at a spacing of 0.2 mm
between peeling bands thereof as viewed from above.
[0081] Observation was performed on the glass substrate obtained in
Example 3 under a microscope. As a result, it was confirmed that
cracking at the end surface of the glass substrate and cracking at
the cutting face thereof were suppressed. The cutting face was
confirmed to be smooth. The glass substrate was observed from a
side thereof under a microscope. FIG. 8 is a schematic side view
showing the glass substrate. It is found that a glass cutting
portion was formed step-wise.
* * * * *