Metal plate shaping method

Abstract

There are provided a step of preparing a plurality of metal plates that has a concave shape in a center principal portion except a predetermined peripheral portion, and a step of executing a thermal treatment to the plurality of metal plates in such a state that a plurality of metal plates are stacked to mate the predetermined peripheral portion with each other and also predetermined peripheral portions are pushed.

Description

BACKGROUND OF THE INVENTION

[0001] 1) Field of the Invention

[0002] The present invention relates to a metal plate shaping method and, more particularly, a method of shaping a metal plate (sealing plate) employed in an organic EL display device having an organic EL (Electroluminescence) layer, etc.

[0003] 2) Description of the Related Art

[0004] In recent years, the organic EL element takes the attention as the self-light emitting element. The organic EL element has such features that this element has the good display characteristic because of its self-light emitting characteristic, this element is excellent in shock resistance because such element is the perfect solid state element, power consumption of this element is low, etc. Therefore, the utilization as the light-emitting element in various display devices is expected.

[0005] FIG. 13 is a sectional view showing an example of the organic EL display device. In this organic EL display device, as shown in FIG. 13, an organic EL element array 102 is formed on a transparent glass substrate 100. The organic EL element has a structure in which an organic EL layer is put between a cathode and an anode. In the organic EL display device, holes injected from the anode and electrons injected from the cathode are recombined with each other in the inside of the organic EL layer to emit the light, and then this light passes through the transparent anode and is emitted to the outside. Thus, the display image can be obtained.

[0006] In such organic EL element, the dot-like or circle-like non-emission display defect that is called the dark spot (dark defect spot) is ready to occur since separation of the electrode and the organic EL layer proceeds due to penetration of the moisture, etc.

[0007] Therefore, a passivation film is formed on the organic EL element array 102 and also the organic EL element array 102 is capped by a back cap 108 that has a concave portion 108a in its center principal portion. A peripheral portion of the back cap 108 except the concave portion 108a is bonded to a peripheral portion of the glass substrate 100 by an adhesive layer 101.

[0008] In this manner, the organic EL element array 102 is arranged in the concave portion 108a of the back cap 108, and an inert gas that does not contain the moisture, or the like is filled in a space 104 of the concave portion 108a. And an adsorbent material 106 adsorbing moisture is arranged in a bottom portion of a concave portion of the back cap 108.

[0009] According to such configuration, not only the penetration of the moisture into the organic EL element array 102 from the outside can be prevented, but also the organic EL element array 102 can be protected from the mechanical impact.

[0010] In many cases, the glass substrate is employed as the back cap 108. The glass substrate has good flatness of the surface, and can mate its coefficient of thermal expansion with the glass substrate 100 on the side of the organic EL element. Therefore, such glass substrate is convenient from such a viewpoint that the reliability of the bonding can be improved.

[0011] In the prior art, the back cap 108 is manufactured by forming the concave portion in the predetermined center portion of the glass substrate by virtue of the sand blast or the wet etching.

[0012] Meanwhile, since not only a thickness of an adsorbent material 106 but also the space 104 between the adsorbent material 106 and the organic EL element array 102 must be assured, a depth of the concave portion 108a of the back cap 108 must be formed relatively deep (e.g., about 0.5 mm).

[0013] For this reason, when the concave portion is formed in the glass substrate by the sand blast or the wet etching, a work efficiency is low because a large amount of working is required, and thus an increase in cost is brought about. Also, because a predetermined strength is required of the glass substrate after the concave portion is formed, the relatively thick glass substrate must be used. As a result, a thickness of the organic EL display device is also increased.

[0014] As the countermeasure, the trial to employ the metal plate as the back cap 108 in place of the glass substrate was made. This trial is such a method that the concave portion is formed in the predetermined center portion of the metal plate by shaping the metal plate by virtue of the stamping, or the like.

[0015] However, according to this method, the problem such that the increase in cost and increase in the thickness can be overcome, nevertheless the metal plate is inferior in flatness of the surface to the glass substrate and also the flatness of the surface is further deteriorated by the stress caused in the stamping. Therefore, such a problem is caused that the reliability of the bonding between the metal plate and the glass substrate on the organic EL element side is lowered. As a result, it is possible that, since the moisture penetrates into the organic EL element from the outside, the above-mentioned display defect is caused.

SUMMARY OF THE INVENTION

[0016] It is an object of the present invention to provide a metal plate shaping method capable of improving the reliability of joint between a metal plate and a substrate of a display device by improving a flatness of an adhesive surface of the metal plate.

[0017] The present invention provides a metal plate shaping method that comprises the steps of preparing a metal plate that has a concave shape in a center principal portion except a predetermined peripheral portion; and executing a thermal treatment in such a state that a plurality of metal plates are stacked to mate the predetermined peripheral portion with each other and also predetermined peripheral portions are being pushed.

[0018] In the present invention, first the metal plate that has the concave shape in the center principal portion except the predetermined peripheral portion is prepared. In this step, the concave shape may be formed by pushing the center principal portion except the predetermined peripheral portion by virtue of the stamping, or the concave shape may be formed by etching the center principal portion of the metal plate to reduce its thickness. Otherwise, the concave shape may be formed by etching the center principal portion of the metal plate to reduce the thickness and then pushing the center principal portion by virtue of the stamping.

[0019] Then, the thermal treatment is applied to the metal plate in such a state that a plurality of metal plates are stacked to bring the predetermined peripheral portion into contact with each other, for example, and also a predetermined pushing pressure is applied to the predetermined peripheral portions by clamping the peripheral portions by virtue of the clamping jig, or the like. At this time, when the concave shape is formed in the metal plate by the stamping, a plurality of metal plates may be stacked while inserting the spacer between the predetermined peripheral portions to prevent the situation that portions of the metal plates except the predetermined peripheral portions are brought into contact mutually and thus deformed.

[0020] In this manner, because the thermal treatment is applied to the metal plates in the state that the predetermined peripheral portions are pushed, not only the step caused due to the stress (internal stress) in the metal plate itself but also the step caused due to the stress by the stamping can be corrected. As a result, the flatness that is equal to or higher than the glass substrate can be obtained on the surface of the predetermined peripheral portion of the metal plate.

[0021] Then, the surface of the predetermined peripheral portion of the metal plate is bonded to the peripheral portion of the substrate of the display device as the bonding surface, and the concave portion in the center principal portion of the metal plate acts as the back cap (sealing plate) that covers the element forming region within a predetermined space.

[0022] As described above, because the bonding surface of the predetermined peripheral portion of the metal plate has the flatness that is equal to or higher than the glass substrate, the reliability of the jointing of the substrate of the display device and the metal plate can be improved. Therefore, if the metal plate shaped by the method of the present invention is employed as the back cap of the organic EL display element, penetration of the moisture into the organic EL element from the outside can be prevented and thus the generation of the display defect can be prevented.

[0023] Also, the metal plate can be employed as the back cap. Therefore, unlike the case of the glass substrate, the increase in cost can be suppressed by using the stamping, and also the sufficient mechanical strength can be obtained even if the thickness of the back cap is thinned. As a result, the thin organic EL display device can be easily manufactured.

[0024] In the above metal plate shaping method, it is preferable that the metal plate is formed of any one selected from a group consisting of an alloy of nickel (Ni) and iron (Fe), an alloy of nickel (Ni), iron (Fe) and cobalt (Co), tungsten (W), and molybdenum (Mo).

[0025] The coefficient of thermal expansion of the Ni—Fe alloy, the Ni—Fe—Co alloy, W or Mo is close to the glass substrate of the display device. Therefore, if the metal plate made of one of these materials is employed as the back cap of the organic EL display element, disadvantages such that, when the stress is applied by the heat, or the like, cracks are generated in the bonding layer due to difference in the coefficient of thermal expansion, and others can be overcome. As a result, the reliability of the jointing of the substrate of the display device and the back cap can be further improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIGS. 1A to 1D are sectional views showing a metal plate shaping method according to a first embodiment of the present invention, wherein FIG. 1B is a sectional view taken along a I-I line in FIG. 1D (plan view);

[0027] FIG. 2A is a perspective view showing an example of the clamping jig employed in the metal plate shaping method according to embodiments of the present invention, and FIG. 2B is a sectional view taken along a II-II line in FIG. 2A;

[0028] FIG. 3A is a sectional view showing an example of the thermal treatment equipment employed in the metal plate shaping method according to the embodiments of the present invention, and FIG. 3B is a view showing an example of the temperature profile in a furnace of the thermal treatment equipment in FIG. 3A;

[0029] FIG. 4 is a sectional view showing a metal plate (back cap) manufactured by the metal plate shaping method according to a first embodiment of the present invention;

[0030] FIG. 5 is a sectional view showing an example of an organic EL display device in which the metal plate in the first embodiment of the present invention is applied as the back cap;

[0031] FIG. 6 is a plan view showing an experimental sample;

[0032] FIGS. 7A to 7C are views showing a flatness of a surface of the metal plate before a planarizing process is applied;

[0033] FIGS. 8A to 8C are views showing the flatness of the surface of the metal plate that is subjected to the planarizing process according to the metal plate shaping method of the present embodiment;

[0034] FIGS. 9A to 9C are views showing the flatness of the surface of the metal plate that is subjected to the planarizing process according to the metal plate shaping method of the present embodiment after the metal plate is bent;

[0035] FIG. 10 is a sectional view showing a metal plate shaping method according to a second embodiment of the present invention;

[0036] FIGS. 11A to 11E are sectional views showing a metal plate shaping method according to a third embodiment of the present invention;

[0037] FIGS. 12A to 12D are sectional views showing a metal plate shaping method according to a fourth embodiment of the present invention; and

[0038] FIG. 13 is a sectional view showing an example of an organic EL display device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Embodiments of the present invention will be explained with reference to the accompanying drawings hereinafter.

[0040] (First Embodiment)

[0041] FIGS. 1A to 1D are views showing a metal plate shaping method according to a first embodiment of the present invention, FIGS. 2A and 2B are views showing an example of the clamping jig employed in the metal plate shaping method according to present embodiments, FIG. 3A is a sectional view showing an example of the thermal treatment equipment employed in the metal plate shaping method according to the present embodiments, FIG. 3B is a view showing an example of the temperature profile in the furnace of the thermal treatment equipment in FIG. 3A, FIG. 4 is a sectional view showing a metal plate (back cap) manufactured by the metal plate shaping method according to the present embodiment, and FIG. 5 is a sectional view showing an example of an organic EL display device in which the metal plate in the present embodiment is applied as the back cap.

[0042] In the metal plate shaping method according to the first embodiment of the present invention, as shown in FIG. 1A, first a metal plate 10a that is made of Ni—Fe alloy (42 alloy), or the like and has a thickness of about 0.25 to 0.3 mm, for example, and a die 26 are prepared. In this case, as the metal plate 10a, Ni—Fe—Co alloy (Kovar), tungsten (W), molybdenum (Mo), aluminum (Al), stainless (SUS304), or the like may be employed in addition to the Ni—Fe alloy.

[0043] Basically this die 26 is composed of a punch 20, a clamping member 22, and a supporting member 24. The metal plate 10a is inserted between the clamping member 22 and the supporting member 24, and then a predetermined portion of the metal plate 10a is pushed by the punch 20 to roll. Thus, the concave portion is formed.

[0044] Then, the metal plate 10a is inserted into such die 26, and the metal plate 10a is pushed by the punch 20 to roll. Thus, as shown in FIGS. 1B and 1D, a metal plate 10 consisting of a bonded portion 10z provided in a predetermined peripheral portion, a rolled portion 10y rolled to be connected to the bonded portion 10z, and a pushed portion 10x connected to the rolled portion 10y is obtained. A concave portion 11 consisting of the pushed portion 10x and the rolled portion 10y is formed in a center principal portion of the metal plate 10. Because this rolled portion 10y is formed by rolling a neighboring portion of the pushed portion 10x of the metal plate when the pushed portion 10x of the metal plate 10 is pushed, a thickness of the rolled portion 10y is reduced rather than the bonded portion 10z and the pushed portion 10x.

[0045] This metal plate 10 serves as a back cap (sealing plate) of a display device such as an organic EL display device, etc. The bonded portion 10z is bonded to a peripheral portion of the glass substrate of the display device via the adhesive layer, and an organic EL element array is arranged in a space of the concave portion 11 and is capped by the metal plate 10.

[0046] In this manner, it is preferable from the viewpoint of improving the reliability of the bonding against the stress such as heat, etc. that, since the metal plate 10 is bonded to the glass plate via the adhesive layer, the Ni—Fe alloy (e.g., 4.5 ppm), a coefficient of thermal expansion of which is close to the glass substrate (e.g., 4.8 ppm), of the above metal materials should be employed. Also, it is also preferable from the similar viewpoint that Ni—Fe—Co alloy, W or Mo should be employed in addition to the Ni—Fe alloy.

[0047] As described above, the metal plate is inferior in flatness of its surface to the glass substrate (glass substrate: 10 to 30 &mgr;m, for example, metal plate: 50 &mgr;m or more, for example), and then the flatness is further deteriorated by the stress applied by the stamping. Hence, the reliability of bonding is lowered by the heat or the mechanical impact after this metal plate 10 is bonded to the display substrate, and it is possible that the display defect occurs in the organic EL display device because the moisture penetrates into the display device from the bonded portion.

[0048] The metal plate shaping method according to the first embodiment of the present invention is invented to planarize a bonding surface 10s of the metal plate 10, which is shaped in this manner, to the extent that is equal to or higher than the flatness of the glass substrate.

[0049] Next, a method of planarizing the bonding surface 10s of the metal plate 10 will be explained hereunder.

[0050] First, as shown in FIG. 1C, a lower plate 12 made of cemented carbide hard metal or ceramic is prepared. A plurality of metal plates 10 are arranged to be stacked on the lower plate 12 such that the bonding surface 10s of the metal plate 10, which is shaped into the shape shown in FIG. 1B, is directed to the lower plate 12 side.

[0051] At this time, the bonding surface 10s of the lowermost metal plate 10 contacts to the lower plate 12, and also a plurality of metal plates 10 are stacked such that their bonded portions 10z come into contact with each other. Also, since a thickness of the rolled portion 10y of the metal plate 10 is thinned rather than other portions by the rolling, a plurality of metal plates 10 are stacked in the situation that their rolled portions 10y do not contact mutually to form a clearance 13 therebetween.

[0052] In this case, in the first embodiment, the pushed portions 10x come into contact mutually when a plurality of metal plates 10 are stacked. Thus, if the number of sheets of the metal plate 10 is increased, it is supposed that the lower metal plates 10 are deformed particularly by their weights. Therefore, it is preferable that the number of stacked sheets should be set to about 10 to 20.

[0053] Next, explanation of a clamping jig that clamps a plurality of metal plates 10, which are stacked on the lower plate 12, will be made hereunder. As shown in FIG. 2A and FIG. 2B, in a clamping jig 40, a clamping plate 30 having a convex portion 30a in the area, which corresponds to the bonded portion 10z of the metal plate 10, and a concave portion 30b in the areas, which correspond to the pushed portion 10x and the rolled portion 10y of the metal plate 10, is arranged on the lower plate 12 on which a plurality of metal plates 10 are stacked and arranged, as described above. As a result, the bonded portions 10z formed on the peripheral portions of the metal plates 10 are put between the peripheral portion of the lower plate 12 and the convex portion 30a of the clamping plate 30.

[0054] An upper plate 32 in which a convex portion 32a is provided in the area that corresponds to the peripheral portion of the clamping plate 30 is arranged on this clamping plate 30. Also, side surface guides 34 which support the upper plate 32 and the lower plate 12 are provided at a beginning portion and an end portion of the upper plate 32 and the lower plate 12 respectively.

[0055] Then, an opening portion 32b is formed at the center portion of the upper plate 32. A cap screw 36 is inserted into the opening portion 32b. A predetermined pushing force is applied to the clamping plate 30 under the upper plate 32 by screwing the cap screw 36. Like the lower plate 12, the clamping plate 30 and the upper plate 32 are made of cemented carbide hard metal, ceramic, or the like.

[0056] The clamping jig 40 is constructed as above. If the cap screw 36 is screwed into a predetermined position, the bonded portions 10z of the metal plates 10 are clamped by the convex portion 30a of the clamping plate 30 and the peripheral portion of the lower plate 12 to have a predetermined pressure. In addition, as explained in FIG. 1C, since the rolled portions 10y of plural metal plates 10 is reduced in thickness rather than other portions, such rolled portions 10y never contact mutually. Therefore, such a drawback is not generated that the rolled portions 10y are affected by the pushing of the bonded portions 10z and thus pushed/deformed unnecessarily. At this time, the bonded portions 10z of the metal plates 10 are pushed by the load of 1 g/mm2, for example.

[0057] In this case, in the above example, the mode in which a plurality of metal plates 10 are stacked and then clamped by the clamping jig 40 is exemplified. But a one sheet of metal plate 10 may be clamped by the clamping jig 40.

[0058] Then, the metal plates 10 the bonded portions 10z of which are clamped by the clamping jig 40 are thermally treated in the thermal treatment equipment. As shown in FIG. 3A, a thermal treatment equipment 50 employed in the present embodiment is a belt conveyer furnace that comprises basically a mesh-like metal belt conveyer 42 for carrying the thermally treated object at a predetermined speed, a thermal treatment furnace 44, and heaters 48 arranged on the top side and the bottom side of the thermal treatment furnace 44 respectively. A cooling chamber 44a is provided adjacent to the thermal treatment furnace 44 in the carrying direction side, and a cooling fan 46 is fitted to the top portion of this cooling chamber 44a.

[0059] Nonoxidizing gas supplying pipes 45 and a nonoxidizing gas exhausting pipe 47 are provided at the top portion of the thermal treatment furnace 44. A nonoxidizing gas such as a nitrogen gas, an argon gas, or the like is supplied to the inside of the thermal treatment furnace 44 via the nonoxidizing gas supplying pipes 45, and then is exhausted to the outside of the thermal treatment furnace 44 via the nonoxidizing gas exhausting pipe 47.

[0060] The thermally treated object is carried into the thermal treatment furnace 44 via a loading portion 44x by the belt conveyer 42 at a predetermined carrying speed, then is subjected to the predetermined thermal treatment during the passage in the thermal treatment furnace 44, then is cooled in the cooling chamber 44a, and then is carried out to the outside via an unloading portion 44y.

[0061] The metal plates 10 that are in the state being clamped by the above clamping jig 40 are thermally treated by using such thermal treatment equipment 50. A temperature profile in the thermal treatment furnace 44 is given such that, as shown in FIG. 3B, first the temperature is increased up to 600 to 800° C., preferably 700° C. at a predetermined programming rate, then this temperature is held for 1 to 2 hour, for example, to execute the thermal treatment, and then the temperature is decreased into about 150° C., for example, in the cooling chamber 44a.

[0062] The temperature profile is set by adjusting a set temperature of the heater 48, a carrying speed (e.g., 20 to 200 mm/min) of the belt conveyer 42, a flow rate of the nitrogen gas, etc. In this case, from the viewpoint such that discoloration must be suppressed by preventing the oxidation of the metal plate 10, preferably the nonoxidizing gas such as nitrogen, argon, or the like should be employed as the atmosphere in the thermal treatment furnace 44. But such atmosphere may be set to the atmospheric atmosphere.

[0063] Then, after the clamping jig 40 is carried from the cooling chamber 44a to the outside by the belt conveyer 42 and then the temperature comes down to a room temperature, such clamping jig 40 is disassembled and then a plurality of metal plates 10 are detached individually. With the above, as shown in FIG. 4, the metal plate 10 that is worked by the metal plate shaping method according to the first embodiment of the present invention can be manufactured. Since the bonded portion 10z of the metal plate 10 is subjected to the thermal treatment at the temperature of about 700° C., for example, in the situation that such portion is clamped by a predetermined force that is applied by the clamping jig 40, the bonded portion 10z of the metal plate 10 containing the bonding surface 10s is made flat and a degree of flatness can be set to about 50 &mgr;m or less.

[0064] As described above, because the planarizing process according to the present embodiment is applied, not only the step caused due to the stress (internal stress) contained in the metal plate 10 itself but also the step caused due to the stress in the stamping can be corrected. As a result, the flatness that is equal to or higher than the glass substrate can be obtained.

[0065] Then, as shown in FIG. 5, the metal plate 10 in the present embodiment acts as the back cap (sealing plate) when the bonding surface 10s is bonded to the peripheral portion of the transparent glass substrate 60, on which the predetermined organic EL element array 64 is formed, via the adhesive layer 62. Also, an adsorbent material 66 is adhered onto a bottom surface of the concave portion 11 of the metal plate 10.

[0066] In the metal plate 10 in the present embodiment, because the flatness that is equal to or higher than the glass substrate can be obtained, the metal plate 10 can be bonded to the glass substrate 60 with the good adhesion and the high reliability. As a result, since the penetration of the moisture into the organic EL element array 64 from the outside can be prevented, generation of the display defect in the organic EL display device can be prevented.

[0067] Also, the metal plate can be employed as the back cap. Therefore, unlike the case that the glass substrate is employed, not only the increase in cost can be suppressed by using the stamping but also the sufficient mechanical strength can be obtained even if a thickness of the back cap is reduced. As a result, the thin organic EL display device can be easily manufactured.

[0068] In addition, since the Ni—Fe alloy, or the like, a coefficient of thermal expansion of which is close to the glass substrate 60 of the display device, is employed as the material of the metal plate 10, the reliability of the bonding against the stress such as thermal stress, etc. can be further improved, like the case that the glass substrate is employed.

[0069] The inventors of this application have made experiments to validate effects of the metal plate shaping method of the present embodiment. FIG. 6 is a plan view showing an experimental sample, FIGS. 7A to 7C are views showing the flatness of the surface of the metal plate before the planarizing process is applied, FIGS. 8A to 8C are views showing the flatness of the surface of the metal plate that is subjected to the planarizing process according to the metal plate shaping method of the present embodiment, and FIGS. 9A to 9C are views showing the flatness of the surface of the metal plate that is subjected to the planarizing process according to the metal plate shaping method of the present embodiment after the metal plate is bent.

[0070] First, as shown in FIG. 6, a ring-like metal plate 10b, which corresponds to the above bonded portion 10z of the metal plate 10, is formed as an experimental sample by etching the metal plate made of the Ni—Fe alloy. Then, the flatness (a degree of flatness) in the infinitesimal area (X axis×Y axis) of the surface of the ring-like metal plate 10b was measured by the non-contact type step measuring apparatus.

[0071] As shown in FIGS. 7A to 7C, it was checked that a step of about ±10 &mgr;m is generated in three infinitesimal areas of the surface of the ring-like metal plate 10b respectively. This is the step that is generated by the stress (internal stress) caused in the metal plate in itself. Normally the flatness is in proportion to square of the area. Thus, since the area of the above bonded portion 10z of the metal plate 10 is considerably larger than the area in the measured infinitesimal area, it can be easily understood that the step is well over 50 &mgr;m in an absolute value.

[0072] Then, in order to validate the effect of the planarizing process according to the metal plate shaping method of the present embodiment, in the situation that the ring-like metal plates 10b are fitted into and clamped by the clamping jig 40, the planarizing process was carried out by executing the thermal treatment according to the similar method to the above method.

[0073] According to this result, as shown in FIGS. 8A to 8C, the steps in above three infinitesimal areas were suppressed smaller than about ±5 &mgr;m respectively. Thus, it was confirmed that the metal plate shaping method of the present embodiment is effective to improve the flatness of the surface of the metal plate.

[0074] Also, when hardness of the surface of the ring-like metal plate 10b, to which the planarizing process has been applied, was measured by the Vickers hardness tester, the Vickers hardness (Hv) of about 210 obtained before the planarizing process is applied was reduced to about 190 after the planarizing process. This means that the stress (internal stress) of the ring-like metal plate 10b is removed and the surface is planarized.

[0075] Next, the inventors of this application intentionally bent the ring-like metal plate 10b shown in FIG. 6 and then executed the planarizing process according to the metal plate shaping method of the present embodiment. This is because the flatness of the surface of the metal plate is not only decided by the stress (internal stress) caused in the metal plate in itself but also deteriorated by the stress applied by the stamping.

[0076] As shown in FIG. 9A, when the ring-like metal plate 10b is bent by applying the stress, the step of about 120 &mgr;m was generated upwardly in an absolute value. As the result that the planarizing process was applied to this metal plate by the similar method to the above method, as shown in FIG. 9A or 9C, conversely the step of about 15 &mgr;m was generated downwardly, nevertheless it was confirmed that such process has the effect on the improvement of the flatness. In this case, FIG. 9C is prepared by mating a scale of an ordinate (flatness) of FIG. 9B with ordinates (flatness) of FIG. 7 and FIG. 8.

[0077] (Second Embodiment)

[0078] FIG. 10 is a sectional view showing a metal plate shaping method according to a second embodiment of the present invention. A difference of the second embodiment from the first embodiment is that a plurality of metal plates 10 are fitted into the clamping jig 40 in the state that a spacer is inserted between their bonded portions 10z respectively. Since other steps are similar to those in the first embodiment, their detailed explanation will be omitted herein.

[0079] As described above, in the first embodiment, if a plurality of metal plates 10 are stacked, the pushed portions 10x contact mutually. Thus, such a case is supposed that, if the number of stacked sheets of the metal plates 10 is increased, the lower metal plates 10 are deformed particularly by their weights. The metal plate shaping method according to the second embodiment is provided to overcome such disadvantage.

[0080] In the metal plate shaping method according to the second embodiment, first the same plate as the metal plate 10 shown in FIG. 1B is formed by the similar method to the first embodiment. Then, as shown in FIG. 10, a plurality of metal plates 10 are stacked while inserting a spacer 70 between the bonded portions 10z respectively. This spacer 70 is made of cemented carbide hard metal, ceramic, or the like and has a ring-like shape that corresponds to the bonded portion 10z of the metal plate.

[0081] At this time, since the spacer 70 is arranged between the bonded portions 10z of a plurality of metal plates 10, the pushed portion 10x of the metal plate 10 is arranged high by a thickness of the spacer 70. As a result, not only a clearance 13 is present between their rolled portions 10y of a plurality of metal plates 10, but also a clearance 13a is present between their pushed portions 10x. Thus, unlike the first embodiment, a plurality of metal plates except the bonded portions 10z do not come into contact mutually.

[0082] The metal plates 10 are stacked in this manner, and then the thermal treatment is applied in the state that the bonded portions 10z of the metal plates 10 are being pushed by the predetermined force according to the similar method to the first embodiment. Thus, the metal plate 10 serving as the back cap is manufactured.

[0083] According to the metal plate shaping method in the second embodiment, even if a large number of metal plates 10 are stacked, portions of the metal plates 10 except the bonded portions 10z are not brought into contact mutually. Thus, there is no possibility that the disadvantage of the deformation of the stacked metal plates is caused. Therefore, for example, 100 sheets or more of the metal plates 10 can be stacked and fitted into the clamping jig 40, and then the thermal treatment can be applied collectively to these metal plates 10. As a result, a production efficiency can be improved.

[0084] (Third Embodiment)

[0085] FIGS. 11A to 11E are sectional views showing a metal plate shaping method according to a third embodiment of the present invention. A difference of the third embodiment from the second embodiment is that, when a plurality of metal plates 10 are stacked, portions of the metal plates 10 except the bonded portions 10z are not brought into contact mutually without the spacer. Since other steps are similar to those in the first embodiment, their detailed explanation will be omitted herein.

[0086] As described above, in the first embodiment, such a case is supposed that, if a plurality of metal plates 10 is stacked, the metal plates 10 are deformed by their weights. The metal plate shaping method according to the third embodiment is provided to overcome such disadvantage without the insertion of the spacer.

[0087] In the metal plate shaping method according to the third embodiment, as shown in FIG. 11A, first the metal plate 10a that has a film thickness of about 0.25 to 0.3 mm is prepared, like the first embodiment. Then, as shown in FIG. 11B, a pattern (not shown) of a resist film is formed on a predetermined peripheral portion serving as the bonded portion of the metal plate 10a. Then, the metal plate 10a is etched to a depth of about 50 to 150 &mgr;m by the wet etching while using this resist film as a mask. Thereby, a thin body portion is formed in the metal plate 10a In this case, the thin body portion of the metal plate 10a may be formed by stamping instead of etching.

[0088] Then, as shown in FIG. 11C, a die 26x having the punch 20, the clamping member 22, and the supporting member 24 is prepared. Then, the metal plate 10a is inserted into the die 26x to direct its etched surface to the punch 20 side, and then the metal plate 10a is pushed by the punch 20. Accordingly, as shown in FIG. 11D, the etched portion of the metal plate 10a is pushed to form the pushed portion 10x and the rolled portion 10y, and as a result the concave portion 11 is formed, thereby the metal plate 10 is obtained.

[0089] Then, as shown in FIG. 11E, plural sheets of metal plates 10 are stacked on the lower plate 12 of the clamping jig 40 by the similar method to the first embodiment. At this time, the pushed portion 10x and the rolled portion 10y are etched previously and their thicknesses are reduced rather than the bonded portion 10z. Therefore, as also shown in FIG. 11E, the pushed portion 10x and the rolled portion 10y of plural metal plates 10 do not contact mutually and the clearances 13, 13a are provided between the metal plates 10 respectively.

[0090] A plurality of sheets of metal plates 10 are stacked in this manner, and then the thermal treatment is applied in the state that the bonded portions 10z of the metal plates 10 are being pushed by the predetermined force according to the similar method to the first embodiment. Thus, the metal plate 10 serving as the back cap is manufactured.

[0091] According to the third embodiment, like the second embodiment, even if a large number of metal plates are stacked, portions of the metal plates except the bonded portions 10z are not brought into contact mutually. Thus, such a possibility can be eliminated that the disadvantage of the deformation of the stacked metal plates is caused. Therefore, for example, 100 sheets or more of the metal plates 10 can be stacked and fitted into the clamping jig 40, and then the thermal treatment can be applied collectively to these metal plates 10.

[0092] In addition, since there is no need to insert the spacers between a plurality of metal plates 10, an operation of fitting a plurality of metal plates 10 into the clamping jig 40 can be simplified. As a result, a production efficiency can be further improved.

[0093] (Fourth Embodiment)

[0094] FIGS. 12A to 12D are sectional views showing a metal plate shaping method according to a fourth embodiment of the present invention. A difference of the metal plate shaping method in the second embodiment from the first to third embodiments is that a concave portion is formed in the metal plate by the etching without use of the stamping.

[0095] In the first to third embodiments, the mode in which the thin metal plate (e.g., 0.25 to 0.3 mm) is employed is exemplified respectively. However, it is difficult to work a thick metal plate (e.g., 0.7 to 0.8 mm) by the stamping. Therefore, in the fourth embodiment, the concave portion is formed by applying the half-etching to the metal plate in the thickness direction.

[0096] In the metal plate shaping method of the fourth embodiment, as shown in FIG. 12A, first a metal plate 10a having a thickness of about 0.7 to 0.8 mm, for example, is prepared. Then, as shown in FIG. 12B, a resist film 15 is patterned on the predetermined peripheral portion serving as the bonded portion 10z of the metal plate 10a, and then the metal plate 10a is etched by the wet etching while using this resist film 15 as a mask. Thus, as shown in FIG. 12C, the concave portion 11 having a depth of about 0.5 mm is formed and also the bonded portion 10z is defined, thereby the metal plate 10 is obtained.

[0097] Then, as shown in FIG. 12D, the metal plates 10 are fitted into the clamping jig 40 such that the bonding surface 10s of the metal plate 10 is directed to the lower plate 12 side. Then, the thermal treatment is executed in the state that the bonded portions 10z of a plurality of metal plates 10 are being pushed by the predetermined force. Thus, the metal plate 10 serving as the back cap is manufactured.

[0098] According to the fourth embodiment, the metal plate having a large thickness can be easily applied as the back cap of the organic EL display device. Also, like the second and third embodiments, even if a large number of metal plates are stacked, portions of the metal plates except the bonded portions 10z are not brought into contact mutually. Thus, there is no possibility that the disadvantage of the deformation of the metal plates is caused. Therefore, for example, 100 sheets or more of the metal plates 10 can be stacked and fitted into the clamping jig 40, and then the thermal treatment can be applied collectively to these metal plates 10. In addition, unlike the second embodiment, there is no need to insert the spacer between the bonded portions 10z of a plurality of metal plates 10.

Claims

1. A metal plate shaping method comprising the steps of:

preparing a plurality of metal plates that have a concave shape in a center principal portion except a predetermined peripheral portion; and

executing a thermal treatment to the plurality of metal plates in such a state that the plurality of metal plates are stacked to mate the predetermined peripheral portion with each other and also predetermined peripheral portions are pushed.

2. A metal plate shaping method comprising the steps of:

preparing a metal plate that has a concave shape in a center principal portion except a predetermined peripheral portion; and

executing a thermal treatment to the metal plate in such a state that the predetermined peripheral portion is pushed.

3. The metal plate shaping method according to claim 1, wherein the step of preparing the plurality of metal plates includes the step of forming the concave shape by pushing the center principal portion of a metal plate by virtue of a stamping.

4. The metal plate shaping method according to claim 1, wherein the step of preparing the plurality of metal plates includes the steps of,

reducing a thickness by etching the center principal portion of a metal plate, and

forming the concave shape by pushing the center principal portion of the metal plate by virtue of a stamping.

5. The metal plate shaping method according to claim 1, wherein the step of preparing the plurality of metal plates includes the step of forming the concave shape by etching the center principal portion of a metal plate to reduce a thickness.

6. The metal plate shaping method according to claim 1, wherein, in the step of executing the thermal treatment, the plurality of metal plates are stacked to insert a spacer between the predetermined peripheral portions.

7. The metal plate shaping method according to claim 1, wherein the metal plate is formed of any one selected from a group consisting of an alloy of nickel (Ni) and iron (Fe), an alloy of nickel (Ni), iron (Fe) and cobalt (Co), tungsten (W), and molybdenum (Mo).

8. The metal plate shaping method according to claim 1, wherein the thermal treatment is executed at a temperature of 600 to 800° C.

9. The metal plate shaping method according to claim 1, wherein the thermal treatment is executed in an atmosphere of a nonoxidizing gas.