WO2010086072A1

WO2010086072A1 - Assembly and process for a gas tight sealing of oled-components

Info

Publication number: WO2010086072A1
Application number: PCT/EP2009/067678
Authority: WO
Inventors: Uwe Keim; Robert Michael Hartung
Original assignee: Centrotherm Thermal Solutions Gmbh + Co. Kg
Priority date: 2009-01-30
Filing date: 2009-12-21
Publication date: 2010-08-05
Also published as: DE102009006932A1

Abstract

The invention concerns an assembly for gas tight sealing of OLED components comprising an OLED layer structure on a substrate and a covering glass plate as well as a solder at the rim area between. It is an object of the invention to realize a device for a fast and effective vacuum tight sealing of OLED devices with a low thermal load of the OLED devices. The invention is characterized by the fact that a chamber (1) which can be evacuated having an upper assembling opening (2) provided with a window (3) and with a substrate mount (5), which is movable from below against the window (3) to grout the OLED devices (6) which are preassembled positioned onto the mount (5), whereby a laser beam (14) of a laser beam welding device can be directed through the window (3) at the level between the substrate (7) and a covering glass plate (8).

Description

Assembly and process for a gas tight sealing of OLED-

Components

The invention concerns an assembly for gas tight sealrng of OLED components comprising an OLED layer structure on a substrate and a covering glass plate as well as a solder at the rim area between.

Organic light emitting diodes so called OLED devices consists of a plurality of organic layers on a substrate which can be contacted by electrodes on the upper and lower sides. The substrate is made of glass normally which is covered by a conductable Indium-/Tmoxide layer. On this follows a stack of organic hole and electron transport materials and an anorganic transparent cathode. The OLED device is transparent by himselve m the switch off state by integration of two transparent electrodes.

In addition the lower electrode can be structured so that display appliances are possible with elements which are switched individual.

An example for such an OLED device is described in EP 1 487 027.

Since water and oxygen would destroy components of OLED devices inevitable it is necessary to seal it gas tight to protect them from environmental influences. This is realized normally by a glass plate which covers the upper electrode layer and which must be connected m the rim portion with the substrate gas tight.

In the meantime the organic substances are more resistant against water and oxygen but however remain a certain responsiveness of the highly reactxve ion layer made of calcium and barium. Also the borders of the stack of layers can be infiltrated by corrosion with the result that the effective glowing pixel area is reduced what would disturb monitor appliances .

At this reason the closure of the OLED devices against water and oxygen is meaningful for a useful life as long as possible. Furthermore it must be reached a good storing ability of such devices which should be as possible at 10 years typically.

Useful closures are glass plates which are fused in the rim portion which realize a gas tight connection at this way. Most useful therefore is laser beam welding with pulsed laser beam. During this it must considered the high temperature responsiveness of OLED devices and it must provided for a temperature burden as short as possible. But this is not easy to realize by laser welding because of the high melting temperature of glass. In the WO 03/013779 Al is described a process for laser welding of working pieces, especially for assembling of components in fine mechanics or micro system engineering what is useful for welding of glass plates in general in case that the laser beam is focussed accordingly. The necessary moving and positioning is performed by the beam control or with a positioning and moving system for the device relative to the laser beam.

Such an arrangement is not useful for welding of glass plates under vacuum and clean room conditions for OLED appliances. Moreover the glass plates are substantial thermal loaded so that any use for sealing of OLED devices diverges . Durxng the manufacturing process of OLED devices it is indispensable to perforin a gas exchange between the glass plates before the gas tight welding of the substrate with a glass covering plate is performed what is possible by creating a vacuum and what guarantees that neither water/water dust nor oxygen will be enclosed.

It is an object of the invention to realize a device for a fast and effective vacuum tight sealing of OLED devices with a low thermal load of the OLED devices. This object is solved basing on an assembly as mentioned in the beginning with a chamber which can be evacuated having an upper assembling opening provided with a window and with a substrate mount, which can be moved from below against the window to grout the OLED devices which are preassembled positioned onto the mount, whereby a laser beam of a laser beam welding device can be directed through the window at the level between the substrate and the covering glass plate .

Therewith it is possible to seal OLED devices m a gas tight manner without any danger of them since the temperature will catch the necessary welding temperature within the welding area only over a short time interval whereby the surrounding will be heated at 60 °C in maximum and more heating it is not allowed. In a first embodiment of the invention consists the window of a glass plate, a quartz glass plate or another plate with sufficient thickness which is transparent for a laser beam depending on the wave length of the laser beam to use and a seal which is positioned between the window and the rim portion, to guarantee the gas respectively the vacuum tightness .

Furthermore the mount for the substrate is mounted on a bar which is movable xn a vertical direction and which is leaded through a vacuum lead through in the wall of the vacuum chamber to the exterior and is connected with a drive unit. At this way the assembling of the substrate mount with OLED devices can be realized easy and fast.

The drive unit is preferably designed of the art of a hydraulic, pneumatic or a spring-loaded drive device to generate a wall defined compressive force of the substrate mount against the window to realize a good controlling of the pressure load. The drive device can be connected with the bar over a spring additional or the substrate mount is mounted on the bar by a spring load. In these cases the vertical movement of the bar can be performed with an easy path control since the spring limits the load force. The special advantage of this construction is to see in that, that the different thermal expansion components of the joined partner are compensated.

In another embodiment of the invention is the substrate mount or the bar connected with a force measuring instrument to avoid any exceeding mechanical load of the OLED devices.

The substrate mount is connected with a cooling device finally e.g. in the shape of a liguid cooling device for cooling the ground plate mounted on thereof. At this way the thermal load of the OLED devices is furthermore reduced. The object on which the invention is based is solved furthermore by a process for a gas tight sealing of OLED devices by driving out the substrate mount through the assembling opening and loading with an OLED component together with a covering glass plate under simultaneous application of a solder onto the rim of the OLED component between substrate and covering glass plate, lowering the substrate mount through the assembling opening and closure of it gas tight with the window, evacuating the chamber over a predefined time whereby the space between substrate and coverrng glass plate is evacuated simultaneously, pressing the populated substrate mount against the window with a given contact pressure force onto the wrndow, focussing a laser beam through the window and melting the solder by leading the laser beam along the solder as well as lowering of the substrate mount after performing the sealing process and ventilation of the chamber and removing of the gas tight closed OLED device. In a continuation of the process is the solder is heated until a temperature of 300 ⁰C so that any exceeding thermal load of the OLED devices is prevented.

The temperature of the solder can be measured m a non- contacting manner during the melting process so that the laser beam can be continued by reaching the nominal temperature of the solder place.

The assembly is also useful for a vacuum tight enclosure of opaque or transparent substrates with glass plates which are solderable with the same solder. For example it is possible to enclosure papers or others which are delicate for environmental toxins between the glass plates m a gas tight manner .

The assembly according the invention is also useful for a vacuum tight closing of container shaped substrates with a glass plate.

The assembly according of the invention is also useful for the gas tight closure of OLED devices.

The invention will be described on an example. The enclosed drawings show: Figure 1: a schematic depiction of the assembly according the invention to load a substrate mount with an OLED and a closed vacuum chamber; and

Figure 2: the assembly according figure 1 during the welding process .

According Figure 1 consists the inventive assembly of a chamber 1 which can be evacuated and which is provided with an upper fitting opening 2 which closable by a window 3. The window 3 can close the fitting opening 2 by way of a sealing 4. The window 3 consists of a glass plate, a quartz glass plate or a plate which is transparent for a laser beam, whereby the sealing 4 is positioned between the window 3 and the outer rim of the mounting fitting opening 2.

Within the chamber 1 is arranged a substrate mount 5 to fit pre-mounted OLED devices 6 on it. The OLED devices 6 covers a substrate 7 as base with an organic layer structure on it a covering glass plate 8 and a solder 9 which is inserted circumferential onto the rim between the substrate 7 and the covering glass plate 8 what is used to seal the OLED device at a gas tight manner. The substrate consists normally of glass or another solderable material. The substrate mount 5 is mounted on a vertical bar 10 which is leaded through a vacuum lead through 11 in the wall 12 of the chamber 1 at the lower side and is connected with a not shown linear drive unit. The sealing of the vacuum lead through 11 is performed by a sealing 13. The linear drive unit can be a hydraulic or pneumatic drive unit to generate a defined pressing force to press the substrate mount 5 with a given pressure force against the window 3. In addition it is possible that the drive unit works against a spring force to prevent each overload of the pre-mounted OLED devices 6 surely.

In an alternate version the substrate mount 5 can be assembled on the bar 10 in a slidable manner against a sprxng. In both cases the force which affects against the OLED devices can be limited easy and thermal expansions are limited. Moreover the vertical movement of the substrate mount 5 respective the bar 10 can be limited by way of a distance control.

The substrate mount 5 or the bar 10 can be connected with a force control device in addition to prevent any exceeding mechanical load on the OLED devices 6 respective stop the vertical movement at reaching a specified value and to keep the loading force constant.

During the window 3 is opened the substrate mount 5 can be driven out through the fitting opening 2 so that a simple and fast fitting of the substrate mount with an OLED device is possible or alternate the removal of it. The substrate mount 5 must be driven back into the chamber 1 so that the fitting opening 2 can be closed again.

In addition the substrate mount 5 is provided with a cooling device, e.g. as a water cooling device to ensure that the OLED devices are not heated momentary over 60 ⁰C during the sealing process.

The OLED devices 6 must be grouted during the soldering process which is performed by pressing against the window 3. Assumption therefore is that the chamber 1 is evacuated in a preceding step so that the window 3 is pressed against the frame of the assembling opening 2 with a force which traverses the loading force of the substrate mount 5. After that a laser beam 14 is focussed through the window onto a level between substrate and covering glass plate 8 respective at the solder and is then leaded along the solder whereby the solder is melted.

Therewith it is possible to seal OLED devices simply and gas tight without danger since the temperature reaches the soldering temperature m the proximate soldering area only during a short time whereas the surrounding is heated at 60 ⁰C m maximum. Additional can be used a non contacting temperature measuring device to metering the solder temperature so that the laser beam can be continued after reaching the melting temperature. At this manner it is possible to perform the sealing process automatic with a high quality.

The gas tight sealing of the pre-mounted and onto the substrate mount 7 positioned OLED devices 6 is performed by several process steps. First the substrate mount 5 is moved out through the previous opened fitting opening 2 and is fitted with an OLED device as well as a covering glass plate 8 after a solder 9 is fitted onto the rim of the OLED device 6 between substrate 7 and the covering glass plate 8. After that the substrate mount 5 is moved back into the chamber 1 through the fitting opening 2 which is to close by the window vacuum tight.

After that the chamber 1 is degased with a suitable vacuum pump over a given time period during the space between the substrate 7 and the covering glass plate will be evacuated respective vented simultaneously. Finally the substrate mount 5 is pressed against the window 3 with a given pressure force F and a laser beam is focussed through the window onto the solder and the solder is melted at any time partial by leading the laser beam along the solder.

At least the substrate mount 5 is lowered exiguous, the chamber ventilated and for removal of the gas tight sealed OLED device 6 is moved out through the fitting opening 2. The solder 9 is heated for a short time interval during laser welding onto a temperature of approximately 300 ⁰C whereas the surrounding of each melting point is held at 60 ⁰C m maximum so that any exceeding thermal load of the OLED' s is prevented certainly.

The assembly and the associated process can be used for sealing of opaque or non-transparent respective transparent substrates of course. A condition therefore is merely that both plates are solderable with the same solder and that at least the upper plate consists of a material which is transparent for the laser beam.

The assembly according the invention can is also useful without problems for a gas tight sealing of container shaped substrates with a bigger internal volume with a covering glass plate.

List of reference numbers:

1 chamber

2 fitting opening

3 window

4 sealing

5 substrate mount

6 OLED device

7 substrate

8 glass plate

9 solder

10 bar

11 lead through

12 wall

13 sealing

14 laser beam

Claims

1. Assembly for gas tight sealing of OLED components comprising an OLED layer structure on a substrate and a covering glass plate as well as a solder at the rim area between with a laser beam welding device, characterized in that a chamber (1) which can be evacuated having an upper assembling opening (2) provided with a window (3) and with a substrate mount (5), which is movable from below against the window (3) to grout the OLED devices (6) which are preassembled positioned onto the mount (5), whereby a laser beam (14) of a laser beam welding device can be directed through the window (3) at the level between the substrate (7) and a covering glass plate (8) .

2. Assembly according to claim 1, characterized by the fact that the window (3) consists of a glass plate, a quartz glass plate or another plate with sufficient thickness, transparent for a laser beam to use whereby a seal (4) is positioned between the window (3) and the rim portion of the fitting opening (2) .

3. Assembly according to claim 1 and 2, characterized by the fact that the substrate mount (5) is mounted on a bar (10) which is movable m vertical direction and which is leaded through a vacuum lead through (11) in the wall of the vacuum chamber (1) to the exterior and is connected with a drive unit .

4. Assembly according claim 3, characterized by the fact that the rive unit is designed from the art of a hydraulic, pneumatic or a spring-loaded drive device to generate a wall defined compressive force (F) of the substrate mount (5) against the window (3) .

5. Assembly according claims 3 and 4. characterized by the fact that the substrate mount (5) is assembled on a bar (10) over a spring additional or the dive unit connected with the bar (10) over a spring load.

6. Assembly according claims 1 to 4, characterized by the fact that the substrate mount (5) or the bar (10) are connected with a force measuring instrument.

7. Assembly according one of the claims 1 to 6, characterized by the fact that the substrate mount (5) is provided with a cooling device.

8. Assembly according claim 7, characterized by the fact that the cooling device is a liquid cooling device.

9. Process for a gas tight sealing of OLED devices with an assembly according claims 1 to 8, characterized by

- driving out the substrate mount through the assembling opening (2) and loading with an OLED component (6) together with a covering glass plate (8) under simultaneous application of a solder (9) onto the rim of the OLED component (8) between substrate (7) and covering glass plate (8), - lowering the substrate mount (5) through the assembling opening (2) and closing it with the window (3) in a gas tight manner,

- evacuating the chamber (1) over a predefined time,

- pressing the populated substrate mount (5) against the window (3) with a given contact pressure force,

- focussing a laser beam (14) through the window (3) and melting the solder (9) by leading the laser beam (14) along the solder (9), as well as - lowering the substrate mount (5) and ventilation of the chamber (1) and removing of the gas tight closed OLED device (6) .

10. Process according claim 9, characterized by the fact that the solder (9) is heated to a temperature up to 300 ⁰C.

11. Process according claim 10, characterized by the fact that the temperature of the solder (9) is monitored during the melting process.

12. Use of the assembly according claims 1 to 8 for a gas tight sealing of opaque, non-transparent or clear respective transparent substrates which are solderable with glass plates .

13. Use of the assembly according the claims 1 to 8 for a gas tight sealing of container shaped substrates with glass plates .

14. Use of the assembly according claims 1 to 8 for a gas right sealing of OLED devices.