Patent Application
20130280495
The present invention relates to a glass film cutting method and a glass film laminate, and more particularly, to a technology for performing appropriate laser scribing on a glass film having a thickness of 200 μm or less.
As is well known, a thinner glass sheet than in conventional ones has been promoted for use in a panel portion, a light transmissive portion, and other such portions of various electronic devices such as a display device as typified by a liquid crystal display device and an organic light-emitting diode display device, and an illumination device as typified by an organic light-emitting diode illumination device from the viewpoint of meeting with thinning and light-weighting, specified types of use, and the like.
Further, the glass sheet to be used as a component that is assembled to the above-mentioned various electronic devices such as a display device and an illumination device is required to have high flexibility, and hence, as this type of glass sheet, a glass sheet having a thickness of 200 μm or less (glass film) has been developed in recent years.
As this type of glass film, a substantially rectangular glass film obtained by removing unnecessary portions after forming is cut and separated into pieces having a predetermined size conforming to the size of, for example, a portion of the various electronic devices to which the glass film is to be assembled. In this case, there is an issue of which method is available for cutting and separating the glass film having a thickness of 200 μm or less (for example, a glass film as a mother glass).
For example, Patent Literature 1 discloses a method of forming scribe lines (laser scribing) due to a change in stress of an internal strain, which is generated in the glass sheet by irradiating the moving glass sheet with a laser beam in a spot shape and cooling, by jetting a coolant, the region heated through the laser beam irradiation. Then, this glass sheet is snapped along the scribe lines, and is accordingly cut and separated into a plurality of glass sheets having a predetermined size.
This type of general laser scribing is described in detail. As illustrated in
However, the above-mentioned laser scribing disclosed in Patent Literature 1 effectively functions for a glass sheet having a thickness more than about 250 μm, but there arises a problem in that the laser scribing in the conventional configuration cannot be utilized effectively for a glass film having a thickness of 200 μm or less as described above.
Specifically, in the former case where the laser scribing is performed on the thick glass sheet, as illustrated in
In the latter case where the laser scribing is performed on the glass film having a thickness of 200 μm or less, however, as illustrated in
As described above, in the case of the glass film having a thickness of 200 μm or less, a sufficient thermal stress cannot be generated in the thickness direction through the laser heating followed by the subsequent cooling, and it is therefore difficult or impossible to form an appropriate scribe line in the glass film.
The present invention has been made in view of the above-mentioned circumstances on the laser scribing, and it is therefore a technical object thereof to form an appropriate scribe line in a glass film having a thickness of 200 μm or less by generating a sufficient thermal stress through laser heating followed by subsequent cooling.
According to the present invention devised to achieve the above-mentioned technical object, there is provided a glass film cutting method, comprising: a laser scribing step of forming a scribe line in a glass film having a thickness of 200 μm or less by propagating an initial crack through laser heating of the glass film followed by subsequent cooling of the glass film; and a laminate manufacturing step of manufacturing a glass film laminate by setting a surface roughness Ra of each of a surface of the glass film to be brought into contact with a support glass, which is configured to support the glass film, and a surface of the support glass to be brought into contact with the glass film to 2.0 nm or less, and by bringing the surface of the glass film and the surface of the support glass into surface contact with each other, followed by the laser scribing step. Note that, the above-mentioned surface roughness Ra is measured through use of a scanning prove microscope (NanoNabi II/S-image) manufactured by SII at a scanning area of 2,000 nm, a scanning frequency of 0.95 Hz, and a scanning data count of X: 256 and Y: 256. The surface roughness Ra is represented by an average value of surface roughnesses Ra at two points in total, that is, one point at a center portion and one point at a corner portion of each of the surfaces of the glass film and the support glass to be brought into contact with each other.
With this configuration, the glass film in which the surface to be brought into contact with the support glass has the surface roughness Ra of 2.0 nm or less and the support glass in which the surface to be brought into contact with the glass film has the surface roughness Ra of 2.0 nm or less are laminated in surface contact (specifically, direct surface contact) with each other, and hence the glass film and the support glass are maintained in a state of appropriately adhering to each other even without using an adhesive or a pressure-sensitive adhesive. Therefore, when the glass film having a thickness of 200 μm or less is subjected to the laser heating followed by the subsequent cooling, the cooled region and the heated region are formed in the thickness direction of the laminate that may be assumed as a unit of the glass film and the support glass obtained through the adhesion. In other words, the cooled region and the heated region are formed in the thickness direction under a state in which the shortage of the thickness of the glass film is compensated with the thickness of the support glass. Therefore, even when the thickness is 200 μm or less, a desired thermal stress (tensile stress) is generated in the thickness direction of the laminate comprising the glass film, and hence the appropriate scribe line is formed in the glass film due to the thermal stress. Note that, it is preferred that the total thickness of the glass film and the support glass, that is, the thickness of the glass film laminate, be 250 μm or more.
In this case, it is preferred to carry out, after the laser scribing step, a separation step of separating, from the support glass, the glass film having the scribe line formed therein, and a snapping step of snapping the separated glass film along the scribe line.
With this configuration, in the separation step, the glass film having the scribe line formed therein, that is, the glass film that is not yet separated into a plurality of pieces, is separated from the support glass. Then, in the snapping step, the glass film is snapped along the scribe line, and is accordingly cut and separated into a plurality of glass films. Thus, in the process of separating the glass film from the support glass, and cutting and separating the glass film into a plurality of pieces, it is possible to effectively prevent such a situation that opposing cleaved surfaces defining the scribe line are brought into locally close contact with each other and chipping, breakage, and the like occur in the cleaved surfaces due to local stress concentration caused by the locally close contact between the cleaved surfaces, thus resulting in generation of a defective product. Further, no adhesive or pressure-sensitive adhesive is interposed as a layer between the glass film and the support glass, and hence it is also possible to avoid such a situation that the glass film is contaminated after the separation. As a result, the plurality of separated glass films can be obtained in a clean state with high quality. Note that, the glass film can be separated from the support glass relatively easily because the glass film and the support glass adhere to each other only through the surface contact therebetween.
Further, the laser scribing step may comprise forming a plurality of scribe lines crossing each other.
With this configuration, in the process of forming one of the scribe lines to be crossed and then forming the other of the scribe lines, when the other of the scribe lines passes across the one of the scribe lines, the other of the scribe lines is formed continuously without being interrupted at a passing point therebetween. This is because, when the one of the scribe lines is formed, the opposing cleaved surfaces defining this scribe line may be assumed to be substantially in contact with each other though the cleaved surfaces are separated from each other in terms of molecules thereof. Aside from the validity of the reason why the above-mentioned phenomenon occurs, as a result of the repetitive experiments conducted by the inventors of the present invention, it is found that, when the other of the scribe lines crosses and passes across the one of the scribe lines after the one of the scribe lines is formed, the other of the scribe lines is formed continuously without being interrupted at the passing point therebetween. Therefore, there is no need to form an initial crack at a leading end portion at which the other of the scribe lines passes across the one of the scribe lines, and hence the position of the initial crack formation can be set only to peripheral edge portions of the glass film. As a result, the work of forming initial cracks is facilitated. Then, the glass film in which the plurality of scribe lines crossing each other are formed as described above is separated from the support glass, and then snapped along the respective scribe lines. Thus, it is possible to prevent in advance such a situation that the opposing cleaved surfaces defining each of the scribe lines are brought into locally close contact with each other and chipping, breakage, and the like occur due to stress concentration caused by the locally close contact between the cleaved surfaces. Accordingly, the glass film can be cut and separated smoothly in a good condition.
Further, the support glass of the glass film laminate may comprise support glasses arranged so as to extend along preset cleaving lines, along which the scribe lines are to be formed in the glass film.
With this configuration, the support glasses are brought into surface contact with the glass film only at a position at which the support glasses extend along the preset cleaving lines, and hence the area of the contact surfaces of the glass film and the support glasses is reduced. Thus, as compared to the case where the glass film and the support glass are laminated in contact with each other over the entire surfaces thereof, it is possible to avoid such a situation that creases are generated due to local separation of the glass film from the support glass at the time of carrying out the laminate manufacturing step. As a result, it is possible to reduce a probability of distortion that may occur in the glass film due to the separation of the glass film. Further, when the glass film is separated from the support glass after the laser scribing step is completed, the separation of the glass film is facilitated. Moreover, when the support glass is washed and dried or inspection is carried out for the presence and absence of remaining foreign matter after the glass film is separated from the support glass, it is possible to reduce the time and effort to be required for those kinds of work.
In addition, the support glass of the glass film laminate may be thinner than the glass film.
With this configuration, it is possible to eliminate waste to be generated from the fact that the support glass to be disposed of is thicker than the glass film, and to achieve light-weighting of the glass film laminate and higher handling efficiency of the glass film laminate. Further, when the glass film is subjected to the laser heating followed by the subsequent cooling under the above-mentioned condition that the support glass is thinner than the glass film, the cooled region and the heated region are formed appropriately in the thickness direction of the glass film laminate. This configuration is advantageous in forming the scribe line more appropriately. Specifically, in view of the fact that there is no need to generate a great thermal stress when forming the scribe line in the glass film unlike a case where the glass film is subjected to full-body cutting, the support glass that is thinner than the glass film is considered to be more advantageous because the generation of the thermal stress is suppressed. Note that, when such a configuration is employed, it is preferred that the thickness of the support glass be 50 μm or more.
On the other hand, according to the present invention devised to achieve the above-mentioned technical object, there is provided a glass film laminate, comprising: a glass film having a thickness of 200 μm or less; and a support glass, which is configured to support the glass film, wherein a surface of the glass film to be brought into contact with the support glass has a surface roughness Ra of 2.0 nm or less, and a surface of the support glass to be brought into contact with the glass film has a surface roughness Ra of 2.0 nm or less, wherein the surface of the glass film and the surface of the support glass are brought into surface contact with each other to laminate the glass film and the support glass, wherein the glass film comprises a scribe line formed therein by propagating an initial crack through laser heating of the glass film followed by subsequent cooling of the glass film, and wherein the support glass is thinner than the glass film.
With this configuration, it is possible to eliminate waste to be generated from the fact that the support glass to be disposed of is thicker than the glass film, and to achieve light-weighting of the glass film laminate and higher handling efficiency of the glass film laminate. In addition, when the steps of manufacturing the glass film laminate and forming the scribe line are carried out in a factory or the like that is different from that for the separation and snapping steps, a large number of glass film laminates having the scribe line formed therein need to be transported, for example, in a packaged state. In this case, it is possible to facilitate the packaging work, increase the number of glass film laminates to be packaged into one bundle, and thus enhance the transportation efficiency. Further, according to the glass film laminate having such a configuration, for the reason described above, the appropriate scribe line is formed in the glass film having a thickness of 200 μm or less.
On the other hand, according to the present invention devised to achieve the above-mentioned technical object, there is provided a glass film laminate, comprising: a glass film having a thickness of 200 μm or less; and a support glass, which is configured to support the glass film, wherein a surface of the glass film to be brought into contact with the support glass has a surface roughness Ra of 2.0 nm or less, and a surface of the support glass to be brought into contact with the glass film has a surface roughness Ra of 2.0 nm or less, wherein the surface of the glass film and the surface of the support glass are brought into surface contact with each other to laminate the glass film and the support glass, and wherein the support glass is thinner than the glass film. In this case, the glass film may be subjected to the scribe line formation in the subsequent step, or may be subjected to full-body cutting and processing related to the manufacture, such as film formation processing.
With this configuration, as in the above-mentioned case, it is possible to eliminate waste to be generated from the fact that the support glass to be disposed of is thicker than the glass film, and to achieve light-weighting of the glass film laminate and higher handling efficiency of the glass film laminate. Further, in this case, the above-mentioned effects on the packaging and transportation are effectively exerted when the step of manufacturing the glass film laminate is carried out in a factory or the like that is different from that for the step of performing the processing related to the manufacture, such as the scribe line formation.
As described above, according to the present invention, the glass film having a thickness of 200 μm or less appropriately adheres to the support glass, and hence, when the glass film is subjected to the laser heating followed by the subsequent cooling, a sufficient thermal stress is generated in the thickness direction of the laminate that may be assumed as a unit of the glass film and the support glass. As a result, the appropriate scribe line can be formed in the glass film.
a A schematic perspective view illustrating a practical situation of a laminate manufacturing step of a glass film cutting method according to an embodiment of the present invention.
b A schematic perspective view illustrating a glass film laminate obtained in the laminate manufacturing step of the glass film cutting method according to the embodiment of the present invention.
a A schematic plan view illustrating the practical situation of the laser scribing step of the glass film cutting method according to the embodiment of the present invention.
b A sectional view taken along the line C-C (and a sectional view taken along the line D-D) of
a An enlarged vertical sectional side view illustrating the practical situation of the laser scribing step of the general glass sheet cutting method according to the conventional technology.
b An enlarged vertical sectional side view of a glass film, for illustrating a problem inherent in the conventional technology.
In the following, a glass film cutting method and a glass film laminate according to embodiments of the present invention are described with reference to the accompanying drawings. Note that,
Now, description is given of an adhesion force to be generated through the surface contact between the glass film 1 and the support glass 2 described above. The adhesion force may be generated due to the following phenomenon. That is, when the contact surface 1a of the glass film 1 is brought into surface contact with the contact surface 2a of the support glass 2, under a condition that the surface roughnesses Ra of both the contact surfaces 1a and 2a are set to 2.0 nm or less, one of the contact surfaces is slightly charged at a positive polarity, and the other of the contact surfaces is slightly charged at a negative polarity. As a result, there arises such a phenomenon that the contact surfaces 1a and 2a attract each other (so-called hydrogen bond). In this case, when the temperatures of both the contact surfaces 1a and 2a become higher than about 250° C., a covalent bond occurs between the contact surfaces 1a and 2a, and hence the glass film 1 and the support glass 2 cannot be separated from each other. When the hydrogen bond occurs as described above, however, the glass film 1 and the support glass 2 can be separated from each other.
According to the above-mentioned configuration of the scribe line forming apparatus 4, through the movement of the laminate 3 in the arrow A1 direction of
In this case, as illustrated in
Further, as illustrated in
As described above, in the process of forming the laminate 3 through the surface contact between the glass film 1 and the support glass 2, forming the scribe lines 17 (17a and 17b) in the glass film 1 of the laminate 3, then separating the glass film 1 from the support glass 2, and separating the glass film 1 into the plurality of glass film pieces 1c, the laminate 3 is packaged and transported in the following two forms. That is, the laminate 3 is packaged and transported in the first form in a case where the laminate manufacturing step is carried out in a factory or the like that is different from that for the subsequent steps (laser scribing step, separation step, and snapping step). In this case, as illustrated in
Through the operation described above, in the laminate manufacturing step, the glass film 1 having the contact surface 1a with the surface roughness Ra of 2.0 nm or less and the support glass 2 having the contact surface 2a with the surface roughness Ra of 2.0 nm or less are laminated in surface contact (specifically, direct surface contact) with each other, and hence the glass film 1 and the support glass 2 are maintained in a state of appropriately adhering to each other even without using an adhesive or a pressure-sensitive adhesive. Therefore, when the glass film 1 is subjected to the heating of the laser beam 8 followed by the subsequent cooling of the cooling fluid 12, the cooled region 13a and the heated region 9a are formed in the thickness direction of the laminate 3 that may be assumed as a unit of the glass film 1 and the support glass 2. In other words, the cooled region 13a and the heated region 9a are formed in the thickness direction under a state in which the shortage of the thickness of the glass film 1 is compensated with the thickness of the support glass 2. Therefore, even in the case of the glass film 1 having a thickness of 200 μm or less, a desired thermal stress (tensile stress) is generated in the thickness direction of the laminate 3 comprising the glass film 1, and hence the appropriate scribe lines 17 (17a and 17b) are formed in the glass film 1 due to the thermal stress.
Moreover, in the separation step following the laminate manufacturing step and the laser scribing step, the glass film 1 having the scribe lines 17 (17a and 17b) formed therein, that is, the glass film 1 that is not yet separated into a plurality of pieces, is separated from the support glass 2, and hence there is no factor in the damage such as a flaw in the glass film 1 at the time of separation, with the result that the generation of a defective product can be avoided effectively. Further, no adhesive or pressure-sensitive adhesive is interposed as a layer between the glass film 1 and the support glass 2, and hence there is even no such situation that the glass film 1 is contaminated after the separation. As a result, the plurality of separated glass film pieces 1c can be obtained in a clean state with high quality.
In addition, in the laminate 3 illustrated in
Specifically, the support glass 2 comprises two longer support glasses 2 extending in a direction along the first preset cleaving lines 6, and six shorter support glasses 2 extending in a direction along the second preset cleaving lines 7. Further, the shorter support glasses 2 abut against the longer support glasses 2 at one or both end portions of the shorter support glasses 2, and are arranged in a direction orthogonal to the longer support glasses 2 under a state in which the longer support glasses 2 are each interposed between the shorter support glasses 2.
Also in the case where the glass film 1 and the support glasses 2 are laminated as in this embodiment, similarly to the above-mentioned embodiment, the scribe lines 17 are smoothly formed in the glass film 1. Further, with this configuration, the area of the contact surfaces of the glass film 1 and the support glasses 2 is reduced, and hence, as compared to the case where the glass film 1 and the support glass 2 are laminated in surface contact with each other over the entire surfaces thereof, it is possible to avoid such a situation that creases are generated due to local separation of the glass film 1 from the support glass 2 at the time of carrying out the laminate manufacturing step. Thus, it is possible to reduce a probability of distortion that may occur in the glass film 1 due to the separation of the glass film 1.
Further, when the glass film 1 is separated from the support glass 2 after the laser scribing step is finished, the separation of the glass film 1 is facilitated. Moreover, when the support glass 2 is washed and dried or inspection is carried out for the presence and absence of remaining foreign matter after the glass film 1 is separated from the support glass 2, it is possible to reduce the time and effort to be required for those kinds of work.
Note that, in the embodiments described above, the thickness of the support glass 2 is set smaller than the thickness of the glass film 1 in which the scribe lines 17 (17a and 17b) are to be formed. Alternatively, the thickness of the support glass 2 may be set larger than the thickness of the glass film 1 as long as the temperature distributions of the heating and cooling are set appropriately. Further, in the embodiments described above, the scribe lines 17 (17a and 17b) are formed under the condition that the laminate 3 is moved and the laser irradiation device 10 and the fluid supplying device 14 are installed stationarily. Alternatively, the laminate 3 may be installed stationarily and the laser irradiation device 10 and the fluid supplying device 14 may be moved. As described above, the laminate 3 illustrated in
As shown in Table 1 below, Examples 1 to 5 of the present invention are each directed to a case where the laminate is manufactured by adhering the glass film, in which the scribe lines are to be formed, and the support glass to each other through the surface contact therebetween, and the surface roughnesses Ra of the contact surfaces of the glass film and the support glass are set to 2.0 nm or less. On the other hand, Comparative Examples 1 and 2 are each directed to a case where the laminate is manufactured from the glass film and the support glass in a manner similar to the above, but one of the surface roughnesses Ra of the contact surfaces of the glass film and the support glass is more than 2.0 nm. Further, Comparative Examples 3 and 4 are each directed to a case where the support glass is not provided.
In each of Examples 1 to 5 and Comparative Examples 1 to 4, through use of alkali-free glass (OA-10G) manufactured by Nippon Electric Glass Co., Ltd., the sizes of the glass film and the support glass were set to 300 mm×300 mm, and the thicknesses of the glass film and the support glass were set as shown in Table 1 below. Further, for the contact surfaces of the glass film and the support glass, glass formed by an overflow downdraw method was used under an unpolished state, or the degrees of polishing and chemical etching were adjusted in terms of concentration, liquid temperature, and processing time.
The surface roughnesses Ra of the contact surfaces of the glass film and the support glass were measured through use of a scanning prove microscope (NanoNabi II/S-image) manufactured by SII at a scanning area of 2,000 nm, a scanning frequency of 0.95 Hz, and a scanning data count of X: 256 and Y: 256. The surface roughness Ra of each of the above-mentioned glass film and support glass was represented by an average value of surface roughnesses Ra at two points in total, that is, one point at a center portion and one point at a corner portion of each of the glass film and the support glass.
At a leading end position on a preset cleaving line of the glass film, an initial crack was formed due to a pressing force of 0.05 MPa through use of a sintered-diamond scribing wheel (manufactured by Mitsuboshi Diamond Industrial Co., LTD.) having a diameter of 2.5 mm, a blade thickness of 0.65 mm, and a wedge angle of 100°. A laser beam used for forming a scribe line was generated through use of a carbon dioxide laser manufactured by Coherent, Inc. as an elliptical beam that was long in a direction along the preset cleaving line through an optical lens system. Further, the scribe line was formed by propagating the initial crack due to a thermal stress generated by heating the glass film through laser irradiation and cooling the glass film through spraying of water at a rate of 4 cc/minute with a pressure of 0.4 MPa. The laser output in this case was 160 w, and the rate of the scribe line formation was 500 mm/second.
In each of the glass films of Examples 1 to 5 and Comparative Examples 1 to 4, three scribe lines were formed at regular intervals in a first direction along one side of the glass film, and three scribe lines were formed at regular intervals also in a second direction orthogonal to the first direction. Further, Table 1 below shows “success and failure of the laser scribing cross cut” in this case, that is, evaluation of results of forming the above-mentioned three scribe lines along the first direction and the above-mentioned three scribe lines along the second direction while crossing each other. In Table 1 below, the symbol “⊚” represents that the scribe lines were formed in an excellent condition, the symbol “∘” represents that the scribe lines were formed in a good condition, which was however slightly inferior to the case of the symbol “⊚”, and the symbol “x” represents that the scribe lines were not formed.
After the above-mentioned scribe lines were formed, a pressure-sensitive adhesive tape was adhered to the corner portion of the glass film to peel the glass film off the support glass. In this manner, the glass film was separated from the support glass. After that, the glass film was snapped along the scribe lines to obtain sixteen glass film pieces. Then, the strengths of those glass film pieces 1c were evaluated by so-called two-point bending, in which the glass film pieces 1c were sequentially sandwiched between two plate-like members 22 and were pressed and bent as illustrated in
Referring to Table 1 above, in each of Examples 1 to 4, the surface roughnesses Ra of both the contact surfaces of the glass film and the support glass were 2.0 nm or less, and the thickness of the laminate was 250 μm or more. Thus, it was confirmed that, even when the thickness of the glass film was 200 μm or less, the scribe lines were formed in the glass film in an excellent condition and the bending fracture stress of each of the glass film pieces after snapping the glass film was sufficiently high as well. Of those examples, Example 3 shows that the thickness of the support glass was smaller than the thickness of the glass film, and hence it was grasped that the scribe lines were formed in a particularly excellent condition and the bending fracture stress of each of the glass film pieces after snapping the glass film was particularly high as well. Further, in Example 5, the surface roughnesses Ra of both the contact surfaces of the glass film and the support glass were 2.0 nm or less and the thickness of the glass film was 200 μm or less, but the thickness of the laminate was 230 μm. Therefore, the scribe lines were formed in the glass film in a slightly inferior condition, and the bending fracture stress of each of the glass film pieces after snapping the glass film was slightly lower as well. It was however confirmed that no problem arose in Example 5, eventually.
In contrast, in Comparative Examples 1 and 2, one of the surface roughness Ra of the contact surface of the glass film and the surface roughness Ra of the contact surface of the support glass was more than 2.0 nm. Thus, the adhesiveness of the contact surfaces of both the glass film and the support glass was not appropriate, and due to the inappropriate adhesiveness, a desired thermal stress was not generated, with the result that the scribe lines were not formed in the glass film. Further, in Comparative Example 3, only the glass film having a thickness of 200 μm was provided, and the support glass was not provided. Therefore, the laser output was adjusted within a range of 50 to 200 w, and the rate of the scribe line formation was adjusted within a range of 50 to 600 mm. However, there was no condition appropriate to form the scribe lines. Moreover, in Comparative Example 4, the scribe lines were formed only in a glass film having a thickness of 100 μm through use of the scribing wheel, and then glass film pieces were obtained through snapping. However, the bending fracture stress of each of those glass film pieces was considerably lower as compared to the glass film pieces according to Examples 1 to 5, thus leading to the conclusion that the glass film pieces had a risk of susceptibility to damage.
From the results described above, it was confirmed that, in Examples 1 to 5 of the present invention, a plurality of scribe lines were formed while crossing each other in a better condition and obtained cleaved end surfaces had a sufficiently high strength to lower the susceptibility to damage as compared to Comparative Examples 1 to 4.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-086555 | Apr 2012 | JP | national |
