Patent Application
20140268520
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2013-050798, filed on Mar. 13, 2013; the entire contents of all of which are incorporated herein by reference.
The present invention relates to a method of manufacturing a member with a sealing material layer, a member with a sealing material layer, and a manufacturing apparatus.
A flat panel display (FPD) such as an organic EL display (Organic Electro-Luminescence Display: OELD) and a plasma display panel (PDP) has a structure in which light-emitting elements are sealed by a glass package in which a pair of glass substrates is sealingly bonded. A liquid crystal display (LCD) also has a structure in which liquid crystals are sealed between a pair of glass substrates. Further, a solar cell such as an organic thin-film solar cell and a dye-sensitized solar cell also has a structure in which solar cell elements (photoelectric conversion elements) are sealed between a pair of glass substrates.
Sealing glass is suitably used for sealing. In the sealing by the sealing glass, for example, a sealing material layer containing the sealing glass is disposed in a frame shape between a pair of glass substrates to form a glass assembly, and this sealing material layer is heated to 400° C. to 600° C. At this time, when the whole glass assembly is heated by using a firing furnace, light emitting elements and so on are likely to be damaged by the heating. Therefore, the application of laser sealing that heats only the sealing material layer by using laser light (sealing laser light) has been considered.
Concretely, the laser sealing is done as follows. First, the sealing glass is mixed with a vehicle to prepare a sealing material paste. This sealing material paste is applied on a frame-shaped sealing region of one of the glass substrates on which the light emitting elements and so on are not mounted, to form a frame-shaped coating layer, and the frame-shaped coating layer is heated to a firing temperature of the sealing glass (temperature equal to or higher than a softening temperature of the sealing glass). Consequently, the sealing glass is melted and is baked to the glass substrate, so that the sealing material layer is formed. Next, the glass substrate having the sealing material layer and the other glass substrate on which the light emitting elements and so on are mounted are stacked via the sealing material layer. Thereafter, the sealing laser light is radiated to the sealing material layer via the glass substrate to heat and melt the sealing material layer. Consequently, the pair of glass substrates is joined by a sealing layer made of the sealing glass.
Conventionally, the formation of the sealing material layer, that is, the firing of the frame-shaped coating layer is done by heating the whole glass substrate including the frame-shaped coating layer by using a heating furnace. However, in a FPD package, organic resin films such as color filters are formed also on the glass substrate on which the light emitting elements and so on are not mounted. Therefore, heating the whole glass substrate causes damage to the organic resin films. Similarly, in the dye-sensitized solar cell as well, since element films and so on are formed on the glass substrate on which the sealing material layer is formed, heating the whole glass substrate causes damage to the element films and so on. Further, when the heating furnace is used, it takes a long time to form the sealing material layer and an energy consumption amount becomes large.
From such a point of view, to use laser light (firing laser light) for the formation of the sealing material layer has been considered. When the firing laser light is used, only the sealing material layer is heated, which suppresses damage to the organic resin films and so on and reduces an energy consumption amount. Incidentally, when the firing laser light is radiated while scanning round the sealing material layer once, a portion where the sealing material layer is discontinuous (gap) sometimes occurs at an irradiation start position or an irradiation finish position. The gap, if excessively large, deteriorates airtightness, adhesive strength, and so on at the time when the pair of glass substrates is sealingly joined.
As a method to reduce the size of the gap, there have been known a method to increase power density of the firing laser light near the irradiation start position and the irradiation finish position, and a method to use a pair of firing laser lights and make the pair of firing laser lights overlap with each other at the irradiation start position and the irradiation finish position. There has also been known a method to lower a scanning speed of the firing laser light near the irradiation finish position.
Increasing the power density in a partial region is likely to generate regions having different firing states unless power control is appropriately performed. The use of the pair of firing laser lights requires a plurality of laser irradiation heads, power control parts, and so on. Further, in the above case, regions having different firing states are generated unless power control is performed appropriately, which is likely to deteriorate airtightness, adhesive strength, and so on.
Reducing the scanning speed halfway is likely to generate regions having different firing states unless power control is appropriately performed. Further, though in a widthwise center portion of the sealing material layer, the gap becomes small due to re-melting, the gap does not necessarily become small at widthwise both end portions. In this case, since the width of the sealing material layer becomes narrow, airtightness, adhesive strength, and so on are not necessarily good. Further, reducing the scanning speed halfway is likely to increase the firing time.
A method of manufacturing a member with a sealing material layer of an embodiment has a substrate preparation step, a coating step, a firing step, and a pre-process step. In the substrate preparation step, a substrate having a frame-shaped sealing region is prepared. In the coating step, a sealing material paste prepared by mixing a sealing material containing sealing glass and a laser absorbing material with a vehicle containing an organic binder is applied on the sealing region of the substrate to form a frame-shaped coating layer. In the firing step, irradiation is performed while firing laser light is scanned along the frame-shaped coating layer, to heat the whole frame-shaped coating layer. This firing step fires the sealing material to form a sealing material layer while removing the organic binder in the frame-shaped coating layer. The pre-process step is performed before the irradiation of the firing step is started. In the pre-process step, irradiation is performed at an irradiation start position for a time within 0.2 D/V to 0.5 D/V [s], where D [mm] and V [mm/s] are a beam diameter and a scanning speed of the firing laser light in the firing step respectively.
A member with a sealing material layer of an embodiment has a substrate having a frame-shaped sealing region and a sealing material layer provided on the sealing region of the substrate, and is manufactured by the method of manufacturing the member with the sealing material layer of the embodiment.
A method of manufacturing an electronic device of an embodiment has a substrate preparation step, a coating step, a firing step, a stacking step, a sealing step, and a pre-process step. In the substrate preparation step, a first substrate having a first surface on which a frame-shaped first sealing region is provided and a second substrate having a second surface on which a second sealing region corresponding to the first sealing region is provided are prepared. In the coating step, a sealing material paste prepared by mixing a sealing material containing sealing glass and a laser absorbing material with a vehicle containing an organic binder is applied on the second sealing region of the second substrate to form a frame-shaped coating layer. In the firing step, irradiation is performed while firing laser light is scanned along the frame-shaped coating layer, to heat the whole frame-shaped coating layer. The firing step fires the sealing material to form a sealing material layer while removing the organic binder in the frame-shaped coating layer. In the stacking step, the first substrate and the second substrate are stacked via the sealing material layer, with the first surface and the second surface facing each other. In the sealing step, the sealing material layer is irradiated with sealing laser light via the first substrate or the second substrate, whereby the sealing material layer is melted and a sealing layer which seals an electronic element part provided between the first substrate and the second substrate is formed. The pre-process step is performed before the irradiation of the firing step is started. In the pre-process step, irradiation is performed at an irradiation start position for a time within 0.2 D/V to 0.5 D/V [s], where D [mm] and V [mm/s] are a beam diameter and a scanning speed of the firing laser light in the firing step respectively.
An electronic device of an embodiment has a first substrate, a second substrate, and a sealing layer. The first substrate has a first surface on which a frame-shaped first sealing region is provided. The second substrate has a second surface on which a second sealing region corresponding to the first sealing region is provided and is disposed, with the first surface and the second surface facing each other. The sealing layer is disposed in a frame shape so as to seal an electronic element part between the first substrate and the second substrate. The electronic device of the embodiment is manufactured by the method of manufacturing the electronic device of the embodiment.
A manufacturing apparatus of an embodiment has a sample stage, a laser light source, a laser irradiation head, a power control part, a moving mechanism, and a scanning control part. On the sample stage, a substrate is placed, the substrate having a frame-shaped coating layer of a sealing material paste prepared by mixing a sealing material containing sealing glass and a laser absorbing material with a vehicle containing an organic binder. The laser light source emits firing laser light. The laser irradiation head has an optical system which irradiates the frame-shaped coating layer of the substrate with the laser light emitted from the laser light source. The power control part controls power of the firing laser light with which the frame-shaped coating layer is irradiated by the laser irradiation head. The moving mechanism relatively moves positions of the sample stage and the laser irradiation head. The scanning control part controls the moving mechanism so that irradiation is performed while the firing laser light is scanned along the frame-shaped coating layer. Further, the scanning control part controls the moving mechanism so that irradiation is performed at an irradiation start position of the firing laser light for a time within 0.2 D/V to 0.5 D/V [s], where D [mm] is a beam diameter of the firing laser light and V [mm/s] is a scanning speed of the firing laser light.
Hereinafter, modes for carrying out the present invention will be described with reference to the drawings.
Examples of the electronic device are FPD, a lighting device, a solar cell, and the like. Examples of FPD are OELD, FED, PDP, LCD, and the like. Examples of the lighting device are those using a light-emitting element such as an OEL element. Examples of the solar cell are sealed-type solar cells such as a dye-sensitized solar cell, a thin-film silicon solar cell, and a compound semiconductor-based solar cell.
First, as illustrated in
The alkali free glass has a coefficient of thermal expansion of about 30 to 50×10−7/K. The soda lime glass has a coefficient of thermal expansion of about 80 to 90×10−7/K. A typical glass composition of the alkali free glass is a composition containing, by mass %, 50% to 70% SiO2, 1% to 20% Al2O3, 0% to 15% B2O3, 0% to 30% MgO, 0% to 30% CaO, 0% to 30% SrO, and 0% to 30% BaO. A typical glass composition of the soda lime glass is a composition containing, by mass %, 55% to 75% SiO2, 0.5% to 10% Al2O3, 2% to 10% CaO, 0% to 10% SrO, 1% to 10% Na2O, and 0% to 10% K2O. Note that the glass composition is not limited to these. Further, at least one of the first and second substrates 1, 2 may be chemically tempered glass or the like.
As illustrated in
As illustrated in
The electronic element part 4 is provided between the surface 1a of the first substrate 1 and the surface 2a of the second substrate 2. In the manufacturing steps of the electronic device illustrated in
For example, when the electronic element part 4 is the dye-sensitized solar cell element or the like, element films such as wiring films and electrode films which form the element structure are formed on each of the surfaces 1a, 2a of the first and second substrates 1, 2. The element films forming the electronic element part 4 and the element structure based on these are formed on at least one of the surfaces 1a, 2a of the first and second substrates 1, 2. Further, on the surface 2a of the second substrate 2 forming the sealing glass substrate, organic resin films such as color filters are sometimes formed as previously described.
On the sealing region 6 of the second substrate 2, the sealing material layer 7 is formed along the whole periphery or substantially the whole periphery of the peripheral portion of the second substrate 2, as illustrated in
As the sealing glass, low-melting-point glass such as tin-phosphoric acid-based glass, bismuth-based glass, vanadium-based glass, or lead-based glass is used, for instance. Among them, low-melting-point sealing glass made of tin-phosphoric acid-based glass or bismuth-based glass is preferable in consideration of sealability (adhesiveness) to the first and second substrates 1, 2 and reliability thereof (adhesion reliability and hermetically) and further an influence on environments and human bodies.
The tin-phosphoric acid-based glass preferably has a composition containing 55 mole % to 68 mole % SnO, 0.5 mole % to 5 mole % SnO2, and 20 mole % to 40 mole % P2O5 (basically, the total amount is 100 mole %).
The bismuth-based glass preferably has a composition containing 70 mass % to 90 mass % Bi2O3, 1 mass % to 20 mass % ZnO, and 2 mass % to 12 mass % B2O3 (basically, the total amount is 100 mass %).
The sealing material contains the laser absorbing material. As the laser absorbing material, at least one kind of metal selected from Fe, Cr, Mn, Co, Ni, and Cu and/or at least one kind of a metal compound of an oxide or the like containing the aforesaid metal are (is) used, for instance. Further, other pigment, for example, an oxide of vanadium (concretely, VO, VO2, and V2O5) may be used.
The content of the laser absorbing material is preferably within a range of 0.1 vol % to 40 vol % to the sealing material. When the content of the laser absorbing material is less than 0.1 vol %, it may not be possible to melt the sealing material layer 7 sufficiently. When the content of the laser absorbing material is over 40 vol %, heat is liable to be generated locally near an interface with the second substrate 2. Further, when the content of the laser absorbing material is over 40 vol %, flowability of the sealing material is liable to deteriorate at the time of its melting to lower adhesiveness with the first substrate 1. The content of the laser absorbing material is preferably 37 vol % or less.
The sealing glass or glass frit, the laser absorbing material, and the low-expansion filler are each in a powdery form or in a particulate form. Hereinafter, the sealing glass powder will be sometimes simply referred to as sealing glass or glass frit, the laser absorbing material particles or the laser absorbing material powder will be sometimes simply referred to as a laser absorbing material, and the low-expansion filler particles or the low-expansion filler powder will be sometimes simply referred to as a low-expansion filler.
The sealing material contains the low-expansion filler lower in a coefficient of thermal expansion than the sealing glass as required. The low-expansion filler is preferably at least one kind selected from silica, alumina, zirconia, zirconium silicate, aluminum titanate, mullite, cordierite, eucryptite, spodumene, a zirconium phosphate-based compound, a quartz solid solution, soda lime glass, and borosilicate glass. Examples of the zirconium phosphate-based compound are (ZrO)2P2O7, NaZr2(PO4)3, KZr2(PO4)3, Ca0.5Zr2(PO4)3, NbZr(PO4)3, Zr2(WO3)(PO4)2, and a complex compound of these.
The content of the low-expansion filler is preferably set so that the coefficient of thermal expansion of the sealing glass becomes close to a coefficient of thermal expansion of the first and second substrates 1, 2. Concretely, though depending on the coefficients of thermal expansion of the sealing glass and the first and second substrates 1, 2, the content is preferably within a range of 0.1 vol % to 50 vol % to the sealing material. The content can be appropriately changed depending on a thickness or the like of the sealing material layer 7. However, when the content is over 50 vol %, flowability of the sealing material at the time of its melting is liable to deteriorate to lower adhesiveness with the first substrate 1. The content is preferably 45 vol % or less. Since the total content of itself and the laser absorbing material influences a property of the sealing material, the total content of these is preferably within a range of 0.1 vol % to 50 vol %.
Hereinafter, a method of forming the sealing material layer 7 (a method of manufacturing a member with a sealing material layer) will be described. First, the laser absorbing material, the low-expansion filler, and so on are compounded to the sealing glass to fabricate the sealing material, and the sealing material is mixed with a vehicle to prepare a sealing material paste.
The vehicle is prepared by melting an organic binder in a solvent. As the organic binder, used is, for example: cellulose-based resin such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, oxyethyl cellulose, benzyl cellulose, propyl cellulose, or nitrocellulose; organic resin such as acrylic resin obtained by polymerizing one kind or more of acrylic monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, butyl acrylate, and 2-hydroxyethyl acrylate; or aliphatic polyolefin-based carbonate resin such as polyethylene carbonate or polypropylene carbonate. As the solvent, in the case of the cellulose-based resin, a solvent such as terpineol, butyl carbitol acetate, or ethylcarbitol acetate is used, in the case of the acrylic resin, a solvent such as methyl ethyl ketone, terpineol, butyl carbitol acetate, or ethyl carbitol acetate is used, and in the case of the aliphatic polyolefin-based carbonate, propylene carbonate, triacetin, or acetyl triethyl citrate is used.
The viscosity of the sealing material paste preferably conforms to the viscosity adapted to an apparatus which applies the sealing material paste on the second substrate 2. The viscosity of the sealing material paste can be adjusted by a ratio of the organic binder and the solvent or a ratio of the sealing material and the vehicle. Well-known additives in a glass paste such as a defoaming agent and a dispersing agent may be added to the sealing material paste. A well-known method using a mixer of a rotation type including stirring blades, a roll mill, a ball mill, or the like is applicable to the preparation of the sealing material paste.
Thereafter, as illustrated in
Further, as illustrated in
A thickness of the frame-shaped coating layer 8 is preferably set so that a thickness after the firing becomes 1 μm or more, that is, so that a thickness of the sealing material layer 7 becomes 1 μm or more. In such a case, by adjusting a formation condition of the frame-shaped coating layer 8, an irradiation condition of the firing laser light 9, or the like, it is possible to fire the frame-shaped coating layer 8 well. The thickness of the frame-shaped coating layer 8 is more preferably set so that the thickness after the firing becomes 150 μm or less. In view of uniform firing, the thickness of the frame-shaped coating layer 8 is still more preferably set so that the thickness after the firing becomes 20 μm or less. A width of the frame-shaped coating layer 8 is preferably set so that a width after the firing becomes 0.1 mm to 5.0 mm, more preferably 0.2 mm to 3.0 mm, and still more preferably 0.5 mm to 2.0 mm.
In the firing, as illustrated in
Here, the firing method using the single firing laser light 9 is illustrated in
A heating temperature of the frame-shaped coating layer 8 is preferably within a range of (T+80) to (T+550) [° C.], where T [° C.] is a softening temperature of the sealing glass. Here, the softening temperature T of the sealing glass refers to a temperature at which the sealing glass is softened to be fluidized but is not crystallized. Further, the temperature of the frame-shaped coating layer 8 when it is irradiated with the firing laser light 9 is a value measured by a radiation thermometer.
By the irradiation with the firing laser light 9 so that the temperature of the frame-shaped coating layer 8 falls within the range of (T+80) to (T+550) [° C.], the sealing glass in the sealing material melts well, whereby the sealing material is baked on the second substrate 2 and the sealing material layer 7 is formed. When the temperature of the frame-shaped coating layer 8 does not reach (T+80) [° C.], there is a risk that only a surface portion of the frame-shaped coating layer 8 melts and the whole frame-shaped coating layer 8 does not uniformly melt. When the temperature of the frame-shaped coating layer 8 is over (T+550) [° C.], the second substrate 2 and the sealing material layer 7 are likely to suffer a crack, a fracture, and the like. Further, by setting the temperature within the aforesaid temperature range, the organic binder is effectively thermally dissolved to be removed from the sealing material layer 7.
A scanning speed of the firing laser light 9 is preferably within a range of 3 mm/s to 20 mm/s. When the scanning speed is less than 3 mm/s, a firing speed lowers, which does not allow the efficient formation of the sealing material layer 7. On the other hand, when the scanning speed is over 20 mm/s, only the surface portion of the frame-shaped coating layer 8 melts to be vitrified, which lowers releasability of gas generated by thermal decomposition of the organic binder to the outside. This sometimes causes the generation of air bubbles inside the sealing material layer 7 or the deformation of its surface due to the air bubbles, and is likely to increase an amount of residual carbon. Using the sealing material layer 7 poor in a removal state of the organic binder for sealing a gap between the first and second substrates 1, 2 is liable to lower bonding strength between the first and second substrates 1, 2 and the sealing layer and to deteriorate airtightness.
Incidentally, in the scanning of the firing laser light 9, the firing laser light 9 may be moved while the position of the second substrate 2 is fixed, the second substrate 2 may be moved while the position of the firing laser light 9 is fixed, or the both may be moved relatively to each other.
The scanning speed of the firing laser light 9 is preferably adjusted according to the thickness of the frame-shaped coating layer 8. For example, in a case of the frame-shaped coating layer 8 whose thickness after the firing becomes less than 5 the scanning speed can be as high as 15 mm/s or more. Further, in a case of the frame-shaped coating layer 8 whose thickness after the firing is over 20 the scanning speed is preferably 5 mm/s or less. In a case of the frame-shaped coating layer 8 whose thickness after the firing is within a range of 5 μm to 20 μM, the scanning speed is preferably within a range of 5 mm/s to 15 mm/s.
A power density of the firing laser light 9 is preferably within a range of 100 W/cm2 to 1100 W/cm2. When the power density is less than 100 W/cm2, it may not be possible to heat the whole frame-shaped coating layer 8 uniformly. When the power density is over 1100 W/cm2, the second substrate 2 is excessively heated, which is likely to cause its crack, fracture, or the like.
Incidentally, in
For example, in order to shorten the firing time of the frame-shaped coating layer 8, it is effective to increase the power and the scanning speed of the firing laser light 9. For example, when the firing laser light 9 with the increased power is radiated from above the frame-shaped coating layer 8, only the surface portion of the frame-shaped coating layer 8 is liable to be vitrified. The vitrification of only the surface portion of the frame-shaped coating layer 8 causes the aforesaid various problems.
In view of these respects, when the firing laser light 9 is radiated to the frame-shaped coating layer 8 from the side, of the second substrate 2, opposite the frame-shaped coating layer 8, the gas generated by the thermal decomposition of the organic binder can escape from the surface of the frame-shaped coating layer 8 even if the vitrification starts from a portion irradiated with the firing laser light 9. It is also effective to radiate the firing laser light 9 from both upper and lower surfaces of the frame-shaped coating layer 8, that is, from the side, of the second substrate 2, where the frame-shaped coating layer 8 is formed and from the side, of the second substrate 2, opposite the frame-shaped coating layer 8.
A beam shape of the firing laser light 9 (that is, a shape of an irradiation spot) is not particularly limited. The beam shape of the firing laser light 9 is generally circular, but is not limited to the circular shape. The beam shape of the firing laser light 9 may be an elliptical shape whose minor axis is a width direction of the frame-shaped coating layer 8. According to the firing laser light 9 whose beam shape is shaped into the elliptical shape, it is possible to increase an irradiation area of the frame-shaped coating layer 8 with the firing laser light 9, and further to increase the scanning speed of the firing laser light 9. Owing to these, it is possible to shorten the firing time of the frame-shaped coating layer 8.
A beam diameter of the firing laser light 9 is preferably 0.5 mm to 3 mm. Note that the beam diameter of the firing laser light 9 is defined in a region where beam intensity becomes 13.5% of the maximum beam intensity. When the beam shape is other than the circular shape, the beam diameter is a size with which the beam intensity becomes 13.5% of the maximum beam intensity in the scanning direction.
In the firing by the firing laser light 9, the frame-shaped coating layer 8 is selectively heated. Even when the surface 2a of the second substrate 2 has the organic resin films such as color filters, the element films, and so on, the selective heating makes it possible to form the sealing material layer 7 in a good condition without giving thermal damage to the organic resin films, the element films, and so on. Further, since the selective heating is excellent in removability of the organic binder, it is possible to obtain the sealing material layer 7 excellent in sealability, reliability, and so on.
Further, as a matter of course, the firing by the firing laser light 9 is also applicable to a case where the organic resin films, the element films, and so on are not formed on the surface 2a of the second substrate 2. In such a case as well, it is possible to obtain the sealing material layer 7 excellent in sealability, reliability, and so on. Further, the firing by the firing laser light 9 consumes less energy compared with a conventional firing step by a heating furnace, and contributes to a reduction of manufacturing man-hour and manufacturing cost. Therefore, in view of energy saving, cost reduction, and so on, the firing by the firing laser light 9 is effective.
In the manufacturing method of the embodiment, a pre-process step is performed before the irradiation of the firing step is started. Performing the pre-process step makes it possible to form the sealing material layer 7 in a good condition and to form the sealing material layer 7 at low cost and with good reproducibility. In the pre-process step, the irradiation is performed at the irradiation start position S for the time within 0.2 D/V to 0.5 D/V [s], where D [mm] and V [mm/s] are the beam diameter and the scanning speed of the firing laser light 9 in the firing step respectively. The firing step and the pre-process step have a relation that the firing step is started immediately after the pre-process step is finished. This is because, if the laser irradiation is once interrupted after the pre-process step and then the firing step is performed, a portion softened by the heating in the pre-process step is cooled, and when this portion is heated again in the firing step, a new gap is liable to be formed. Therefore, it is preferable that the pre-process step and the firing step are continuously performed by using the firing laser light 9 radiated from the same radiation source.
When the sealing material layer 7 is formed by the firing laser light 9, the irradiation is performed while the firing laser light 9 is scanned so that the irradiation start position S and the irradiation finish position F at least partly overlap with each other so as to make the frame-shaped sealing material layer 7 becomes continuous as a whole. However, even if the irradiation is performed while the firing laser light 9 is scanned so that the irradiation start position S and the irradiation finish position F overlap with each other, there sometimes actually occurs a gap near the irradiation start position S or the irradiation finish position F of the sealing material layer 7.
A cause of the generation of the gap is not necessarily clear, but it is inferred as follows. For example, when the irradiation is performed while the firing laser light 9 is scanned along the frame-shaped coating layer 8 from the irradiation start position S to the irradiation finish position F as illustrated in
Performing the pre-process step before the start of the irradiation of the firing step makes it possible to reduce the residual organic binder at the irradiation start position S to reduce the size of the gap. In particular, the irradiation for the time within 0.2 D/V to 0.5 D/V [s] makes it possible to effectively prevent the organic binder from remaining at the irradiation start position S to reduce the size of the gap. When the irradiation time is less than 0.2 D/V, the removal of the organic binder is liable to be insufficient due to the insufficient irradiation time. When the irradiation time is over 0.5 D/V, productivity decreases due to an increase of the irradiation time, and a crack, a fracture, and the like are likely to be generated due to the excessive heating of the second substrate 2.
Concretely, in the pre-process step, the same firing laser light 9 as that used in the firing step is used, the scanning is temporarily stopped before the scanning in the firing step, and the irradiation start position S is irradiated with the firing laser light 9. Such a method eliminates a need for complicated power control which is required in a conventional method of reducing the scanning speed, and the like. Consequently, the generation of regions different in firing state is suppressed and the complication of an apparatus is also suppressed. Further, it is possible to shorten the firing time, as compared with the conventional method of reducing the scanning speed. Further, the gap becomes small irrespective of a widthwise position of the sealing material layer, concretely, not only at a widthwise center portion but also at both end portions, and therefore, the width of the sealing material layer 7 can be ensured, leading to good airtightness, adhesive strength, and so on.
Near the irradiation start position S or the irradiation finish position F of the sealing material layer 7, a gap 71 which is a discontinuous portion of the sealing material layer 7 is formed. In the case of the conventional method of adjusting the scanning speed and so on, the gap 71 is small near a widthwise center portion 72 of the sealing material layer 7, but near side surface portions 73, the gap 71 does not become small. According to the method having the pre-process step, the gap 71 becomes small near both the center portion 72 and the side surface portions 73.
In the method having the pre-process, a gap width G defined as follows can be 55 μm or less. Here, as the gap width G, a distance between a first measurement position 75 and a second measurement position 76 is measured on both side surfaces, and the larger one of these is adopted. Here, the first measurement position 75 is set as follows. Parting lines are drawn to divide the sealing material layer 7 having a projecting portion (in
The scanning speed in the firing step may be constant from the irradiation start position S up to the irradiation finish position F, or after a first firing step where irradiation is performed while the laser light is scanned at a first scanning speed, a second firing step where irradiation is performed while the laser light is scanned at a second scanning speed lower than the first scanning speed may be performed. By reducing the scanning speed when the irradiation finish position F is approached, it is possible to enhance flowability of the sealing glass near the irradiation finish position F to further reduce the size of the gap 71. Incidentally, when the first firing step and the second firing step are performed, in order to find 0.2 D/V to 0.5 D/V [s] in the pre-process step, the scanning speed of the first firing step is defined as the scanning speed V [mm/s].
When the irradiation finish position F of the firing laser light 9 is set at the position beyond the irradiation start position S as illustrated in
As illustrated in
However, reducing the speed from a position excessively apart from the firing end A accordingly increases the scanning time to increase the formation time of the sealing material layer 7, resulting in deterioration in formation efficiency. Therefore, as illustrated in
The scanning speed in the first firing step is preferably within a range of 3 mm/s to 20 mm/s. On the other hand, the scanning speed in the second firing step is preferably 2 mm/s or less. Thus setting the scanning speed makes it possible to further reduce the size of the gap 71. The scanning speed in the second firing step is more preferably 0.5 mm/s or less. A lower limit value of the scanning speed in the second firing step is not particularly limited, but is preferably 0.1 mm/s or more (for example, based on the position short of the firing end A by 1.2 times the beam diameter D), in consideration of excessive heating of the second substrate 2, deterioration of formation efficiency of the sealing material layer 7, and the like.
The scanning speed of the firing laser light 9 in the second firing step is preferably 2 mm/s or less at the position, with the beam center of the firing laser light 9 being the reference point, short of the firing end A by 1.2 times the beam diameter D of the firing laser light 9 as illustrated in
In
When the scanning speed in the second firing step is lower than the scanning speed in the first firing step as described above, the heating temperature of the frame-shaped coating layer 8 sometimes becomes too high if the power density of the firing laser light 9 in the second firing step is the same as that in the first firing step. In such a case, the power density of the firing laser light 9 in the second firing step is preferably made lower than the power density in the first firing step. This can prevent the excessive heating of the frame-shaped coating layer 8 and accompanying cracks, fractures, and so on of the substrate 2 and the sealing material layer 7. However, when the heating temperature of the frame-shaped coating layer 8 in the second firing step is within the aforesaid range, the firing laser light 9 may be radiated under the same condition as that in the first firing step.
Next, a laser firing apparatus as a manufacturing apparatus of the member with the sealing material layer will be described.
The laser firing apparatus 21 includes a sample stage 22 where to place the second substrate 2 having the frame-shaped coating layer 8, a laser light source 23, and a laser irradiation head 24 which irradiates the frame-shaped coating layer 8 with laser light emitted from the laser light source 23, for instance.
The laser irradiation head 24 has an optical system, though not illustrated, which collects the laser light emitted from the laser light source 23 and shapes the laser light into a predetermined beam shape to irradiate the frame-shaped coating layer 8 with the laser light. The optical system will be described later. The laser light emitted from the laser light source 23 is sent to the laser irradiation head 24. The power of the laser light is controlled by a power control part 25. The power control part 25 controls the power of the laser light by, for example, controlling a current input to the laser light source 23. Further, the power control part 25 may have a power modulator which controls the power of the laser light emitted from the laser light source 23.
The firing laser light 9 radiated from the laser irradiation head 24 is radiated while scanning from the irradiation start position S up to the irradiation finish position F of the frame-shaped coating layer 8. Specifically, the laser irradiation head 24 is moved by an X stage 26 in an X direction (that is, a horizontal direction on the drawing in
The X stage 26 and the Y stages 27A, 27B are controlled by a scanning control part 28. The scanning control part 28 temporarily stops the firing laser light 9 at the irradiation start position S so that the irradiation for the time within 0.2 D/V to 0.5 D/V [s] (we-process step) is performed at the irradiation start position S as described above. Thereafter, the scanning control part 28 controls the X stage 26 and the Y stages 27A, 27B (moving mechanism) so that the irradiation is performed while scanning along the frame-shaped coating layer 8 from the irradiation start position S up to the irradiation finish position F (firing step). The laser firing apparatus 21 includes a main control system which comprehensively controls the power control part 25 and the scanning control part 28. The laser firing apparatus 21 further includes a not-illustrated radiation thermometer which measures the firing temperature (heating temperature) of the frame-shaped coating layer 8. The laser firing apparatus 21 preferably includes a suction nozzle, a blast nozzle, or the like which prevents the organic binder removed from the frame-shaped coating layer 8 from adhering to the optical system and the second substrate 2.
The laser irradiation head 24 has an optical fiber 31, a condensing lens 32, an imaging lens 33, a CCD image sensor 34, a dichroic mirror 35, and a reflective mirror 36, as illustrated in
A scanning example of the firing laser light 9 by the laser firing apparatus 21 will be described with reference to
The scanning speed in the firing step may be constant, or after being performed at a first scanning speed, the firing step may be performed at a second scanning speed lower than the first scanning speed. Performing the firing step at the second scanning speed lower than the first scanning speed after performing the firing step at the first scanning speed makes it possible to further reduce the size of the gap 71.
The number of the firing laser lights 9 is not limited to one but may be plural. Specifically, a plurality of laser irradiation heads 4 each capable of independent scanning are prepared, the plural firing laser lights 9 are radiated to the frame-shaped coating layer 8 from the plural laser irradiation heads 24 respectively, whereby the firing time of the frame-shaped coating layer 8 can be shortened. When the plural firing laser lights 9 are used, the irradiation start positions S of these are set so as not to overlap with each other, and the scanning is performed so that the scanning directions are the same rotation direction along the frame-shaped coating layer 8. Further, the irradiation finish positions F of the respective laser lights 9 are set so as to overlap with the irradiation start position S by the other firing laser light 9 that appears first in the moving direction thereof. Further, before the start of the scanning of each of the firing laser lights 9, the irradiation is performed for the time within 0.2 D/V to 0.5 DV [s].
Next, a method of manufacturing the electronic device will be described. As illustrated in
The sealing laser light 10 may be radiated to the sealing material layer 7 through the first substrate 1 from under the first substrate 1 opposite the second substrate 2 of the glass assembly formed by the stacking. Alternatively, the sealing laser light 10 may be radiated from both sides, that is, from above the second substrate 2 of the glass assembly formed by the stacking and from under the first substrate 1 opposite the second substrate 2 of the glass assembly formed by the stacking.
The irradiation is performed while the sealing laser light 10 is scanned along the sealing material layer 7. The sealing material layer 7 melts from its portion irradiated with the laser light 10, and when the irradiation with the sealing laser light 10 is finished, is rapidly cooled to be solidified to fixedly adhere to the first substrate 1. Then, the sealing laser light 10 is radiated all along the periphery of the sealing material layer 7, whereby a sealing layer 11 sealing a gap between the first substrate and the second substrate 2 is formed as illustrated in
According to the manufacturing steps of the electronic device 12 of the embodiment, even when the organic resin films, the element films, and so on are formed on the surface 2a of the second substrate 2, it is possible to form the sealing material layer 7 and the sealing layer 11 in a good condition without giving any thermal damage to these. Therefore, it is possible to fabricate the electronic device 12 excellent in hermetic sealability and reliability without deteriorating a function of the electronic device 12 and its reliability.
Next, concrete examples of the present invention and evaluation results thereof will be described. Note that the following description does not limit the present invention, and changes conforming to the spirit of the present invention can be made.
As a bismuth-based glass frit, one that had a composition containing 83 mass % Bi2O3, 5 mass % B2O3, 11 mass % ZnO, and 1 mass % Al2O3, had a 1 μm average particle size, and had a 410° C. softening temperature was prepared. As a low-expansion filler, a cordierite powder that had a 0.9 μm average particle size and a 12.4 m2/g specific surface area was prepared. As a laser absorbing material, one that had a composition of Fe2O3—Al2O3—MnO—CuO, a 1.9 μm average particle size, and an 8.3 m2/g specific surface area was prepared.
The specific surface areas of the cordierite powder and the laser absorbing material were measured by using a BET specific surface area analyzer (manufactured by Mountech Co., Ltd., device name: Macsorb I-1M model-1201). Measurement conditions were as follows.
adsorbate: nitrogen
carrier gas: helium
measurement method: flow method (BET one point method)
deaeration temperature: 200° C.
deaeration time: twenty minutes
deaeration pressure: N2 gas flow, atmospheric pressure
sample mass: 1 g
85.0 mass % of the aforesaid bismuth-based glass frit, 6.6 mass % of the cordierite powder, and 8.4 mass % of the laser absorbing material were mixed to fabricate a sealing material. 90 mass % of the sealing material was mixed with a 10 mass % vehicle to prepare a sealing material paste. In the vehicle, ethyl cellulose (5 mass %) as an organic binder was dissolved in a solvent (95 mass %) made of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.
Next, a second substrate (dimension: 90×90×0.7 mmt) made of alkali free glass (coefficient of thermal expansion: 38×10−7/K) was prepared. On its sealing region, the sealing material paste was applied in a frame shape by a dispensing method, followed by drying under a condition of 120° C.×ten minutes, whereby a frame-shaped coating layer was formed. The sealing material paste was applied so that a film thickness after the drying became 8 μm.
Next, the second substrate on which the frame-shaped coating layer was formed was disposed on a sample stage of a laser irradiation apparatus. Thereafter, irradiation was first performed for 0.06 seconds while a position of firing laser light was fixed at an irradiation start position of the frame-shaped coating layer (pre-process step). Thereafter, the irradiation was performed up to an irradiation finish position while the firing laser light was scanned round and along the frame-shaped coating layer (start region to finish region) once at a 5 mm/s scanning speed (firing step). A heating temperature of the frame-shaped coating layer at this time was 660° C. In this manner, the whole frame-shaped coating layer was fired by the firing laser light, whereby a member with a sealing material layer having a sealing material layer with a 4.5 μm film thickness and a 0.5 mm width was manufactured.
Here, the irradiation finish position was set at a position so that a beam center of the firing laser light was beyond a firing end of the frame-shaped coating layer by 2 mm in a scanning direction. The start region was a region from the irradiation start position up to a position to which the firing laser light moved by 1.8 mm. The finish region was a region short of the firing end and a region whose beam center was distant from the firing end by 1.8 mm. Further, a region between the start region and the finish region was set as a scanning region. Incidentally, when the firing step is composed of a first firing step and a second firing step, the start region and the scanning region are regions undergoing the first firing step, and the finish region is a region undergoing the second firing step.
The firing laser light had an 808 nm wavelength, a 385 W/cm2 power density, a circular beam shape with a 1.5 mm diameter. The beam shape was measured by using a laser beam profiler (manufactured by Ophir Optonics Solutions Ltd, device name: BS-USB-SP620), and a diameter with which beam intensity became 13.5% of the maximum beam intensity was set as the beam diameter. The laser power was measured by using a power meter (manufactured by Coherent, Inc., device name: FieldMaxll-TO) and a head (manufactured by Coherent, Inc., device name: PM100-19C).
When a state of the sealing material layer was observed by SEM, it was confirmed that the whole sealing material layer was vitrified well. No occurrence of air bubbles and surface deformation ascribable to the organic binder was recognized in the sealing material layer. Further, a gap width G (
Next, the aforesaid member with the sealing material layer (the second substrate having the sealing material layer) and a first substrate (substrate having the same composition and made of alkali free glass having the same shape as those of the second substrate) having an element region were stacked. Next, sealing laser light was radiated through the second substrate from an irradiation start point, which was a side facing a side having the gap, while scanning along the sealing material layer, and the sealing material layer was melted and rapidly cooled to be solidified, whereby the first substrate and the second substrate are sealingly bonded to fabricate a hermetic vessel. It was confirmed that the obtained hermetic vessel was excellent in appearance, bonding strength, and so on and was also excellent in airtightness.
Similarly, 100 pieces of members with a sealing material layer were fabricated, the number of pieces in which the substrate was fractured was checked, and its occurrence ratio was calculated. Further, each of 100 pieces of the members with the sealing material layer was sealingly bonded with the first substrate to fabricate hermetic vessels, the number of the hermetic vessels suffering a fracture in a sealed portion was confirmed, and its occurrence ratio was calculated. Their results are also presented in Table 1.
Members with a sealing material layer were manufactured in the same manner as that of the example 1 except that a beam diameter of laser light, the irradiation time at an irradiation start position (time of a pre-process step), a scanning speed (start region to finish region), power density, heating temperature of a frame-shaped coating layer, and so on were changed to the conditions illustrated in Table 1.
When a state of each of the sealing material layers was observed by SEM, it was confirmed that the whole sealing material layer was vitrified well. Further, in the same manner as that of the example 1, various properties were evaluated. As a result, it was confirmed that bonding strength and airtightness of hermetic vessels were good and the occurrence of fracture (the members with the sealing material layer, the hermetic vessels) was suppressed.
A sealing material layer was formed in the same manner as that of the example 1 except that a scanning speed of laser light in a frame-shaped coating layer (finish region) was changed to 1 mm/s and its power density was changed to 294 W/cm2. A heating temperature of the frame-shaped coating layer at this time was 660° C. The whole frame-shaped coating layer was thus fired by the laser light, whereby a member with a sealing material layer having a 4.5 μm film thickness was manufactured.
When a state of the sealing material layer was observed by SEM, it was confirmed that the whole sealing material layer was vitrified well. Further, various properties were evaluated in the same manner as that of the example 1. As a result, it was confirmed that bonding strength and airtightness of a hermetic vessel were good and the occurrence of fracture (the member with the sealing material layer, the hermetic vessel) was suppressed.
A member with a sealing material layer was manufactured in the same manner as that of the example 1 except that a pre-process step was not performed. Thereafter, various properties were evaluated in the same manner as that of the example 1. As a result, it was confirmed that a gap width G was large, bonding strength and airtightness of a hermetic vessel were deteriorated, and many factures (hermetic vessel) occurred, as presented in Table 1.
A member with a sealing material layer was manufactured in the same manner as that of the example 1 except that the time of a pre-process step was changed to the condition presented in Table 1. Thereafter, various properties were evaluated in the same manner as that of the example 1. As a result, it was confirmed that a gap width G was smaller than those in the examples 1 to 7. However, bonding strength and airtightness of a hermetic vessel were deteriorated, and many factures (the member with the sealing material layer, the hermetic vessel) occurred.
A member with a sealing material layer was manufactured in the same manner as that of the example 1 except that a pre-process step was not performed and a scanning speed in a frame-shaped coating layer (finish region) was changed to 1 mm/s. Thereafter, various properties were evaluated in the same manner as that of the example 1. As a result, it was confirmed that one having good bonding strength and airtightness could be obtained, but since a gap width G was larger than those in the examples 1 to 7, many fractures occurred (the member with the sealing material layer, a hermetic vessel), and a yield as a whole was low.
A member with a sealing material layer was manufactured in the same manner as that of the example 1 except that a pre-process step was not performed and a scanning speed in a frame-shaped coating layer (start region and finish region) was changed to 1 mm/s. Thereafter, various properties were evaluated in the same manner as that of the example 1. As a result, it was confirmed that one having good bonding strength and airtightness could be obtained, but since a gap width G was larger than those in the examples 1 to 7, many fractures occurred (the member with the sealing material layer, a hermetic vessel), and a yield as a whole was low.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-050798 | Mar 2013 | JP | national |
