JP2011137918A - Method for manufacturing metal sealed electronic element - Google Patents

Abstract

A metal-encapsulated electronic device can be manufactured by shortening the sealing process time and increasing the production efficiency, while minimizing adverse effects such as deterioration of the electronic device.
A base metal layer (4, 4 ') is provided on each peripheral edge of a pair of substrates (1, 7) on which an electronic element (2) is formed on one substrate (1), on the base metal layer (4, 4'). Light absorption layers 5 and 5 ′ having a high absorption rate for the laser are provided, and a low melting point metal layer 6 for sealing the electronic element 2 is provided on the light absorption layer 5. A current is passed through the low melting point metal layer 6 to preheat the low melting point metal layer 6, and the low melting point metal layer 6 is heated by irradiating the light absorption layers 5, 5 ′ through the substrate 7 and the base metal layer 4 ′. The electronic element 2 is sealed by melting and joining the low melting point metal layer 6 and the light absorption layer 5 ′.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a metal-encapsulated electronic element in which an electronic element typified by a display medium such as a liquid crystal or a light-emitting medium such as an organic EL is encapsulated.

  2. Description of the Related Art In recent years, light emitting media such as organic EL elements have been used in electronic devices such as mobile phones and music players, and home appliances, and typically have a structure in which electronic devices are sealed between a pair of substrates. Organic EL elements are vulnerable to moisture and oxidation, and in order to extend their operating time, the elements are sealed off from oxygen and moisture in the air during the manufacturing process, and deterioration due to moisture etc. occurs after manufacturing. In order to suppress it, it is necessary to ensure sufficient moisture resistance.

  For example, Patent Document 1 describes a method in which an inorganic protective film made of SiO is provided on an organic EL element and covered with a sealing resin. However, since the sealing resin used here allows moisture to permeate over a long period of time, the lifetime of the organic EL element cannot be essentially prevented from being attenuated.

  The applicant can improve the moisture resistance of an electronic element such as an organic EL element provided between the resin substrates, can suppress deterioration due to moisture or the like of the electronic element, and can also suppress the resin substrate or the electronic element. As a method of manufacturing an electronic device without affecting the process, a method of sealing an electronic element using laser heating by using a low melting point metal as a brazing material and providing a light absorption layer is proposed. (Patent Document 2).

Japanese Patent No. 3354444 JP 2008-251242 A

  Since the method described in Patent Document 2 can block moisture permeation over a long period of time, it is possible to effectively suppress deterioration of the organic EL element. However, since all the heat for melting the low melting point metal is given by the laser light, the process speed is about 2 mm / second, so that improvement in manufacturing efficiency is expected. Simply increasing the speed of the sealing process can increase manufacturing efficiency but reduces sealing accuracy. On the other hand, in order to increase the sealing process speed while maintaining the sealing accuracy as it is, a method such as increasing the laser irradiation power is conceivable. There are limits.

  The present invention has been made in view of the above circumstances, and is capable of shortening the sealing process time to increase manufacturing efficiency and minimizing adverse effects such as deterioration of electronic elements. It aims at providing the manufacturing method of a sealing electronic element.

  According to the method for manufacturing a metal-encapsulated electronic element of the present invention, a base metal layer is provided on each peripheral portion of a pair of substrates on which an electronic element is formed on one substrate, and a laser is provided on at least one of the base metal layers. On the other hand, a light absorption layer having a high absorptance is provided, a low melting point metal layer for sealing the electronic device is provided on the light absorption layer, and a current is passed through at least the low melting point metal layer so that the low melting point metal is provided. Preheating the layer, irradiating the light absorption layer with laser through at least one of the substrate and the base metal layer to heat and melt the low melting point metal layer, and bonding the low melting point metal layer and the light absorption layer Then, the electronic element is sealed.

  When the light absorption layer is provided on one of the base metal layers, the low melting point metal layer is provided with the light absorption layer on both the base metal layer and the light absorption layer. If it is, it is provided on one of the light absorption layers.

When passing an electric current through the low melting point metal layer, it is preferable to pass an electric current through the base metal layer based on a temperature measurement result of the low melting point metal layer.
More preferably, the preheating and / or the heating is performed while cooling the substrate.

  According to the method for manufacturing a metal-encapsulated electronic element of the present invention, a base metal layer is provided on each peripheral portion of a pair of substrates having an electronic element formed on one substrate, and a laser is provided on at least one of the base metal layers. On the other hand, a light absorption layer having a high absorptance is provided, a low melting point metal layer for sealing an electronic device is provided on the light absorption layer, and at least a current is passed through the low melting point metal layer to form a low melting point metal layer. Preheating, irradiating the light absorption layer with laser through at least one substrate and the base metal layer, heating and melting the low melting point metal layer, bonding the low melting point metal layer and the light absorption layer, and sealing the electronic device Therefore, compared with the case where the low melting point metal layer is heated and melted only by the laser, the low melting point metal layer is preheated, so that the required amount of heat supplied by the laser for heating and melting the low melting point metal layer is reduced. So during the laser irradiation process It is possible to shorten the.

It is a schematic diagram which shows the manufacturing process of the organic EL element by 1st embodiment of this invention. It is a top view of FIG.1 (c). FIG. 2 is a perspective view of FIG. It is a top view which shows a part of manufacturing process of the organic EL element by another embodiment of this invention.

  Hereinafter, the method for producing a metal-encapsulated electronic device of the present invention will be described with reference to the drawings, taking an organic EL device as an example. FIG. 1 is a schematic diagram showing a manufacturing process of an organic EL element according to the first embodiment of the present invention. First, an organic EL wiring 8 for supplying a current to the organic EL element 2 is formed on the element forming substrate 1 on which the organic EL element 2 is formed, and a base formed later on the peripheral portion of the element forming substrate 1 For organic EL so as not to be short-circuited by the metal layer 4, the light absorption layer 5 and the low melting point metal layer 6 (hereinafter, the base metal layer 4, the light absorption layer 5 and the low melting point metal layer 6 are collectively referred to as the sealing layer 3). The wiring 8 is covered with an insulating layer 9 (FIG. 1 (a)). The insulating layer 9 may be provided only in a portion where the organic EL element wiring 8 is formed, or may be provided over the entire periphery of the peripheral portion of the element forming substrate 1.

  The element forming substrate 1 can be made of the same material as the sealing substrate 7 to be described later, and specifically, glass, a resin such as PEN, PET, PES, or PC that has been subjected to moisture permeation prevention treatment. it can. In the present embodiment, the element forming substrate 1 is a 447 mm × 340 mm × 0.7 mm glass substrate for a 21-inch liquid crystal display, and the sealing substrate 7 is generally about 5 mm smaller than the element forming substrate 1. (In the drawings, the size is shown larger than the actual size difference for the sake of explanation).

The insulating layer 9 is preferably made of, for example, an insulating oxide such as SiO ₂ , SiON, SiOx, SiO, CeO ₂ , or alumina, or nitride. In this embodiment, a 1 μm thick SiO ₂ layer is formed by plasma CVD. Is provided.

  When the element is vulnerable to heat, it is preferable to perform the following steps (preheating with current, heating with laser) while cooling the element formation substrate 1 and the sealing substrate 7, for example, the organic EL element described in this embodiment In this case, it is preferable that the element formation substrate 1 and the sealing substrate 7 are cooled while being cooled to a temperature of 80 ° C. or lower. Note that the substrate may be cooled in all steps after the step of providing the insulating layer.

  Next, the base metal layer 4 is formed on the insulating layer 9, the light absorption layer 5 is formed on the formed base metal layer 4, and the low melting point metal layer 6 is further formed thereon (FIG. 1B). Similarly, the base metal layer 4 ′ and the light absorption layer 5 ′ are sequentially formed on the sealing substrate 7 so as to face the position where the sealing layer 3 of the element formation substrate 1 is provided. 1B shows a mode in which the light absorption layer 5 is provided on the sealing layer 3 of the element formation substrate 1 and the light absorption layer 5 ′ is provided on the sealing substrate 7 side. It is good also as an aspect by which the light absorption layer was provided in any one of the sealing layer 3 of the element formation board | substrate 1, and the sealing board | substrate 7. FIG. When providing a light absorption layer in any one, the low melting-point metal layer 6 is provided on the provided light absorption layer.

  The base metal layers 4 and 4 ′ are layers for bonding with increasing adhesion to the element formation substrate 1 (the insulating layer 9 when the insulating layer 9 is provided all around the periphery). Although depending on the material, for example, Cr, Ti, Ni, etc. are preferable. In this embodiment, a Cr film having a width of 0.5 mm and a thickness of 5 nm is provided by vacuum deposition. Note that the formation method of the base metal layer is not limited to vacuum deposition, and a laser transfer method or an ion sputtering method may be used.

  The light absorption layers 5 and 5 ′ are irradiated to increase the temperature of the light absorption layer to such an extent that the preheated low melting point metal layer is melted while keeping the temperature rise of the element formation substrate 1 and the sealing substrate 7 low. A layer having a sufficiently high absorption rate with respect to the wavelength of the laser beam (a layer having a maximum absorption with respect to the wavelength of the laser), such as Au, Ni, Cu, Cr, Mo, W, etc. In the embodiment, an Au film having a width of 0.5 mm and a thickness of 200 nm is provided by vacuum deposition.

  The low melting point metal layer 6 is a metal that conducts current and is a layer made of a metal (including an alloy) having a low melting point (having a melting point of 250 ° C. or lower), for example, In, Sn, In—Sn alloy, Low melting point metals such as Sn / Bi / Ag alloy, Sn / Ag alloy, Sn / Ag / Cu alloy, Sn / Ag / Cu / Bi alloy are preferred. In this embodiment, the In layer having a thickness of 2 μm is vacuumed. It is provided by vapor deposition. Depending on the balance with the sealing process, the thickness of the low melting point metal layer may be about 10 μm at the maximum.

  Subsequently, the probe-like electrode 10 is brought into contact with the upper surface of the sealing layer 3 and the low melting point metal layer 6 so that a voltage is applied, and a current is passed through the sealing layer 3 to cause the low melting point metal layer 6 to flow. Is preheated (FIG. 1 (c)). FIG. 1C shows a mode in which a current is passed before the low melting point metal layer 6 of the element formation substrate 1 and the light absorption layer 5 ′ on the sealing substrate 7 are overlapped. After the low melting point metal layer 6 of the formation substrate 1 and the light absorption layer 5 ′ on the sealing substrate 7 are overlapped (state shown in FIG. 1 (d)), the current may flow.

  FIG. 2 shows a plan view of the electrode 10 in contact with it, and FIG. 3 shows a perspective view thereof. 2 and 3, the position (pattern) of the sealing layer 3 is indicated by a broken line. As shown in FIGS. 2 and 3, the sealing layer 3 is formed in a one-stroke pattern. At this time, as shown in FIG. 2, when a voltage is applied to both ends of the pattern of the sealing layer 3, in order to prevent a portion that is not preheated from the sealing layer 3, the pattern gap is minimized. A constriction is provided in the pattern of the sealing layer 3 while taking a space in a portion connected to the electrode so that the distance between the patterns is 0.3 mm.

  The preheating by the current can reduce the takt time of the entire electronic device sealing process by utilizing the waiting time of the laser heating process. The heat generation efficiency per time varies depending on the preheating temperature, element temperature, wiring resistance, and cooling conditions, but it is preferable that the heat generation efficiency of preheating by current is higher than that by laser heating described later. The electrode 10 is connected to a temperature measuring device such as a non-contact thermometer capable of measuring the temperature of the low melting point metal layer 6, and is applied to the sealing layer 3 based on the temperature measurement result measured here. It is connected to a current control device that controls the amount of current to flow. Thereby, when the temperature of the low melting point metal layer 6 is low, the current amount is increased by the current control device, and when the temperature of the low melting point metal layer 6 is high, the current amount is decreased.

  Since the sealing layer 3 is provided in the peripheral part of the element formation board | substrate 1, it can avoid preheating the part in which the organic EL element 2 was formed, and can preheat. If the heat insulation performance and heat dissipation performance of the substrate are high, the temperature of the sealing layer 3 can be preheated to a temperature higher than the breakdown temperature of the organic EL element 2. Moreover, if the element formation substrate 1 and the sealing substrate 7 are cooled as described above, the temperature of the low melting point metal layer 6 can be further increased.

  Next, the low melting point metal layer 6 of the element formation substrate 1 and the light absorption layer 5 'on the sealing substrate 7 are overlapped and irradiated with laser (FIG. 1 (d)). The above-described current may be stopped at this stage, or may continue to flow until the light absorption layer 5 ′ and the low melting point metal layer 6 are sealed by the laser. Since the low-melting point metal layer 6 is preheated by passing an electric current, the time until the low-melting point metal layer 6 is melted can be shortened as compared with heating only by the laser.

  The laser irradiation can be performed using an irradiation apparatus as described in FIG. 3 of Japanese Patent Application Laid-Open No. 2008-251242, for example, and the laser is transmitted through the sealing substrate 7 and the base metal layer 4 ′ to the light absorption layer at the peripheral portion. Irradiate to scan 5 and 5 '. In this manner, by irradiating the light absorption layer at the peripheral portion with the laser, heating of the portion where the organic EL element 2 is disposed can be avoided. Note that laser irradiation may be performed through the base metal layer 4 from the element formation substrate 1 side.

  Although the wavelength of the laser depends on the material of the light absorption layer, a wavelength that transmits through the sealing substrate and is absorbed by the light absorption layer is preferable. For example, when the sealing substrate is glass and the light absorption layer is Au When the sealing substrate is 405 nm and the light absorption layer is Cr, a laser having a wavelength of 1550 nm is used. Accordingly, the low melting point metal layer 6 preheated by flowing the current can be heated and melted, and the organic EL element 2 is sealed by joining the low melting point metal layer 6 and the light absorption layer 5 ′. Can do.

  According to the manufacture of the metal-encapsulated electronic device of the present invention as described above, the low melting point metal layer is preheated as compared with the case where the low melting point metal layer is heated and melted only with a laser. The necessary heat supply amount of the laser for heating and melting the layer can be reduced, and the irradiation process time of the laser beam can be shortened.

  In the manufacture of the metal-encapsulated electronic device of the present invention, a current is passed through the low melting point metal layer to preheat the low melting point metal layer, and then the low melting point metal layer is heated and melted with a laser. When the flow means is the main means for heating the low-melting point metal layer and the laser is used for preliminary heating (that is, contrary to the present invention), the temperature of the electronic element portion will rise. However, since laser heating can give a lot of heat before the applied heat spreads, even in a situation where the temperature of the element part rises only by current heating, as in the present invention By using the current as the preheating means and the laser as the heating and melting means, the temperature of the low melting point metal layer can be raised to the melting point or higher without raising the temperature of the element portion.

This will be specifically described. In the manufacturing process shown in the first embodiment, the resistance value of the pattern in which the sealing layer is formed as shown in FIG. When a current of 400 mA is passed through the sealing layer pattern, heat is generated by 15 W. Here, assuming that the thermal conductivity of glass is 0.9 W / m · K, and the heat transfer coefficient between glass and air is 4 W / m ² · K, heat transfer to air is performed when the low melting point metal layer is at 80 ° C. Since the heat radiation by is 9 W, it is possible to sufficiently preheat if a current of at most 400 mA flows. At this time, the current value is controlled by measuring the temperature of the low-melting point metal layer with a temperature measuring device so that the desired temperature, here 80 ° C., is obtained. The temperature at a point 5 mm away from the pattern of the sealing layer is 62 ° C., for example, the temperature at a point 10 mm away from the pattern of the sealing layer is 50 ° C. Therefore, if the sealing layer is formed by using a space of at least 5 mm from the pattern of the sealing layer as a soldering space for the base metal layer, the pattern of the sealing layer can be preheated without exceeding the heat resistance temperature of the organic EL element. it can.

  Since the melting point of the low melting point metal layer In exemplified above is 156.3 ° C., when the preheating is performed up to 80 ° C., the amount of heat necessary for heating with the laser to the melting point of the low melting point metal layer is the preheating. It becomes 1/2 compared with the case where it does not perform. Therefore, the laser irradiation time can be shortened, and the sealing process speed can be 4 mm / min, that is, twice as fast as the case of only laser heating. The process time when only laser heating is performed at a speed of 2 mm / min is 13 minutes for a 21-inch liquid crystal display. Therefore, if preheating is performed, the process time can be reduced to 6 minutes and 30 seconds.

FIG. 4 is a plan view showing a part of a manufacturing process according to another embodiment in which the positions of the electrodes are changed in the first embodiment. FIG. 4 shows a mode in which electrode connection positions are provided on a diagonal line. In the first embodiment, except that a pattern is applied so that a voltage is applied by contacting a probe-like electrode diagonally. The configuration is the same as described. The resistance value of the wiring pattern formed in this way is 20Ω. For example, when a current of 1 A is passed through this pattern, heat is generated by 20 W. When the heat conductivity of the glass is 0.9 W / m · K and air at 25 ° C. is blown so that the heat transfer coefficient between the glass and air is 20 W / m ² · K, the low melting point metal layer is 80 ° C. In the state, heat dissipation by heat transfer to the air is 15 W, so it is sufficient to flow a current of 1 A at most. Similarly to the above, the current value is controlled by measuring the temperature of the low-melting point metal layer with a temperature measuring device so that the desired temperature, in this case 80 ° C., is obtained. The temperature at a point 3 mm away from the pattern of the sealing layer is 55 ° C., and the temperature at a point 5 mm away from the pattern of the sealing layer is 45 ° C. Therefore, if the sealing layer is formed by using a space of at least 3 mm from the pattern of the sealing layer as a soldering space for the base metal layer, the pattern can be preheated without exceeding the heat resistance temperature of the organic EL element.

  As described above, since the melting point of the low melting point metal layer In is 156.3 ° C., when preheating is performed up to 80 ° C., the amount of heat necessary for heating with the laser up to the melting point of the low melting point metal layer is preheated. It becomes 1/2 compared with the case where there is no. Accordingly, the laser irradiation time can be shortened, and the sealing process speed can be 4 mm / min, that is, twice as fast as the case of only laser heating. For a 21-inch liquid crystal display, the process time of only laser heating 13 Minutes can be reduced to 6 minutes 30 seconds.

DESCRIPTION OF SYMBOLS 1 Element formation board | substrate 2 Organic EL element 3 Sealing layer 4,4 'Base metal layer 5,5' Light absorption layer 6 Low melting point metal layer 7 Sealing substrate 8 Organic EL element wiring 9 Insulating layer 10 Electrode

Claims (3)

  A base metal layer is provided on each peripheral portion of a pair of substrates on which electronic elements are formed on one substrate, a light absorption layer having a high absorption rate for a laser is provided on at least one of the base metal layers, A low melting point metal layer for sealing the electronic element is provided on the light absorption layer, and at least one of the substrate and the base is preheated by flowing a current through the low melting point metal layer. The light absorption layer is irradiated with a laser through a metal layer to heat and melt the low melting point metal layer, and the electronic device is sealed by joining the low melting point metal layer and the light absorption layer. A method for manufacturing a metal-encapsulated electronic device.   2. The method of manufacturing a metal-encapsulated electronic device according to claim 1, wherein a current is passed through the low-melting-point metal layer based on a temperature measurement result of the low-melting-point metal layer.   3. The method of manufacturing a metal-encapsulated electronic device according to claim 1, wherein the preheating and / or the heating is performed while cooling the substrate.

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