This patent application claims the priority of German patent application 10361790.6, the disclosure content of which is hereby incorporated by reference.
The invention relates to an electronic component comprising a flexible substrate, and to a method for producing such a component. The invention also relates to a display based on a flexible substrate and to a method for producing such a display.
Known methods and installations for producing electronic components primarily proceed from a rigid substrate or carrier of the component and are almost exclusively designed as so-called batch processes. By way of example, rigid glass substrates are generally used for the production of organic LEDs.
An economically expedient batch method for producing electronic, in particular optoelectronic, components on flexible substrates has not been disclosed heretofore. The previous methods based on rigid substrates are generally unsuitable for handling flexible substrates.
It is desirable for the handling of flexible substrates for producing electronic, in particular optoelectronic, components on such substrates to be adapted to already existing manufacturing installations provided for batch processes. This obviates a high outlay for development and construction of new installations specially geared to the production of components with flexible substrates.
One object of the present invention is to provide a method of the type mentioned in the introduction which enables the use of conventional batch processes. Another object of the present invention is to provide an organic light-emitting diode arrangement (OLED) and a display which can be produced according to such a method.
These and other objects are attained in accordance with one aspect of the present invention directed to a method for producing an electronic component is specified. In a first step of the method, a flexible substrate is provided in this case. In a next step, the flexible substrate is connected to a process carrier, which is mechanically more stable than the flexible substrate. In a subsequent method step, an electronic component is formed on the flexible substrate. Finally, the process carrier is removed from the flexible substrate.
It is important that the steps of the method described proceed in the order presented. It is possible, moreover, for further intermediate steps to be integrated into the method.
The process carrier described is particularly distinguished by the fact that it is sufficiently mechanically stable to enable processing of the flexible substrate.
The connection between the process carrier and the flexible substrate is preferably configured in a releasable fashion. By way of example, such a connection may be imparted by a magnetic force between substrate and process carrier. In this case, the connection between substrate and process carrier must be strong enough to enable processing of the flexible substrate. Once the electronic component has then been formed on the flexible substrate, the process carrier can be released relatively easily from the substrate without the substrate or the process carrier being damaged in doing so. In this way, the same process carrier can be utilized a number of times.
In the method, a flexible substrate is fixed on a comparatively rigid process carrier by means of a rereleasable adhesion, i.e. the process carrier is more rigid than the flexible substrate and thus sufficiently mechanically stable for the further processing of the substrate and thus also mechanically more stable than the flexible substrate. The process carrier preferably has similar chemical and physical properties to the flexible substrate. Usually, the flexible substrates are polymer-based and can have a variety of thicknesses and be formed as a layer sequence.
What is advantageous about the method described is that the process carrier, because of the rereleasable connection to the substrate, can be removed again from the latter completely or almost completely. The process carrier can then be reused without a high effort.
In the method described, the flexible substrate may undergo conventional processes known for example from the processing of organic light-emitting diodes on glass substrates in existing manufacturing installations, including lithography, solution and cleaning baths, vacuum steps, but also printing processes on the process carrier. The flexible substrate can be removed again from the process carrier at the end of processing, that is to say after the encapsulation of the electronic or optoelectronic components.
In the case of a magnetic adhesion between substrate and process carrier, after running through the complete process for producing the component on or in the substrate, the process carrier can be stripped again from the substrate without any residues. The process carrier can be separated from the substrate simply by being pulled away.
What is advantageous about a connection between substrate and process carrier by means of a thermoplastic material is that thermoplastic material can be removed largely without any residues, and without a high effort, from a polymer-based film and for example a glass substrate as carrier. In order to remove the process carrier from the substrate, the thermoplastic material is preferably melted. The process carrier and the substrate are then pulled away from one another.
In a preferred embodiment, an area region or a plurality of area regions of the substrate is or are fixed on the process carrier, the area region or the area regions forming a grid-like pattern. Such a grid-like pattern may have a plurality of quadrangular, square, triangular units or units of other shapes. The size of these units may correspond to the size of the finished components or contain a plurality of finished components.
According to another aspect of the invention, the method described above is used for producing a display having a flexible film.
Another aspect of the present invention is directed to an optoelectronic element having at least one layer sequence containing an active zone, and a flexible substrate, on which the layer sequence is arranged, wherein the substrate at least partly has a magnetic or magnetizable layer on its substrate side remote from the layer sequence.
A further aspect of the present invention is directed to a display having a flexible substrate, which has a front side and a rear side, a radiation-generating display element being arranged on the front side, wherein the rear side at least partly has a magnetic or magnetizable layer.
a and 1b respectively show a diagrammatic plan view and side view of a flexible film together with functional layers which are processed according to a first exemplary embodiment of the method according to the invention,
a and 2b respectively show a diagrammatic plan view and side view of a flexible film together with functional layers which are processed according to a second exemplary embodiment of the method according to the invention,
a and 3b respectively show a diagrammatic plan view and sectional view of a flexible film together with functional layers which are processed according to a third exemplary embodiment of the method according to the invention, and
In the exemplary embodiments, identical or identically acting constituent parts are provided with identical reference symbols. In principle, the figures are not to be regarded as true to scale. In principle, the individual constituent parts are also not illustrated with the actual relative sizes with respect to one another.
a illustrates a flexible film 1, which, in this first exemplary embodiment of the methods according to the invention, is used for producing a flexible OLED (organic light-emitting diode) display.
The film comprises for example a flexible polymer or a polymer mixture which is flexible. Before the further processing of the film, a magnetic layer 3 is applied on a side of the film 1 which is not provided for the application of further e.g. functional layers. The magnetic layer 3 may be applied by means of vapor deposition or sputtering, if appropriate in conjunction with a corresponding mask. In this example, the magnetic layer 3 has permalloy (namely an alloy comprising approximately 21.5% Fe and approximately 78.5% Ni) and is applied only at the edge region of the film 1. The thickness of the magnetic layer 3 depends on parameters such as the specific holding force of the magnet and the process carrier 2.
b shows the film 1 after or during the further processing for producing an OLED display. Before the further processing of the film 1, a mechanically stable process carrier 2 which adheres magnetically is brought into contact with the film 1. By means of magnetic adhesion, the process carrier 2 is fixed on the magnetic layer 3 and therefore indirectly on the film 1. The process carrier 2 is preferably formed as a plate.
The film 1 strengthened in this way may then be subjected for example to a conventional batch process for producing an OLED display.
Depending on the size and weight of the film 1, the magnetic layer 3 may be applied only at the edge region of the film 1. Generally, a fixing only at the edge region of the film 1 suffices if the surface of the film 1 is relatively small or the film 1 is relatively light. By way of example, a permalloy magnetic layer 3 having a width of 10 mm and a thickness of 500 nm at the edge of a 15 cm×15 cm film 1 made of a PET (Polyethylene Terephthalate) having a thickness of 100 μm suffices to hold the latter on a 5 mm thick process carrier 2 made of steel ST37 which also has a size of approximately 15 cm×15 cm. Further magnetic materials such as iron, nickel and alnico are also suitable as material for the process carrier 2.
The film 1 shown in
a and 3b show a third exemplary embodiment of the invention, in which the magnetic layer 3 is not only formed at the edge region of the film 1. In this case, the magnetic layer 3 has a regular grid-like pattern over the entire surface of the film 1. By way of example, the repeating units of the grid-like pattern are square in this case (see
The configuration of the magnetic layer 3 as a grid-like pattern is suitable in particular for large-area films 1. By virtue of the grid-like magnetic layer 3, the weight of the process carrier 2 that is to be held can be distributed better and therefore be borne more firmly. Unfavorable stripping away of the process carrier 2 from the magnetic layer 3 or the film 1 during the further processing of the film 1 is then less likely.
The size of the grid-forming units may correspond to the size of one or more finished displays or one or more finished components. By way of example, the film 1 illustrated in
In all the examples described above, it is optionally possible for the residual parts of the magnetic layer 3 to be removed after singulation.
The configuration of the magnetic layer 3 in the exemplary embodiments described above may also apply analogously to an embodiment of the invention in which the process carrier 2 is fixed to the film 1 by means of a thermoplastic material. The thermoplastic material may then be applied or coated onto the film 1 in accordance with the patterns of the magnetic layer 3 explained above. The thermoplastic material may be connected to a stable process carrier 2 (e.g. a glass plate) for example by means of ultrasonic welding or resistance heating (heating press). The thermoplastic material preferably liquefies as a result of the heating (e.g. between 100° C. and 200° C.). The connection between the thermoplastic material and the process carrier solidifies through cooling of the thermoplastic material.
After the further processing of the film 1, the thermoplastic material may be removed again thermally from the film 1 and from the process carrier 2. Unlike in the case of the adhesive according to the prior art, the thermoplastic material can be removed from the film 1 and the process carrier 2 without any residues. Consequently, the thermoplastic material cannot form a disturbance in the finished product and the process carrier can be reused without any further effort.
In a similar manner, the patterns of the magnetic layer 3 explained above may also be used for an embodiment of the invention in which area regions of the film 1 are melted and the film 1 is connected to a process carrier 2 as a result of the melting. Said area regions may be defined in accordance with the patterns of the magnetic layer 3. The melting can be performed, for example, by the above-mentioned ultrasonic welding or resistance heating (e.g. using a heating press).
In order to remove the process carrier from the substrate, the area region where substrate and process carrier are joined can be melted. Substrate and process carrier are then pulled away from each other. The melting can be performed, for example, as explained above.
The invention is not restricted by the description on the basis of the exemplary embodiments. Rather, the invention encompasses any new feature and also any combination of features, which in particular comprises any combination of features in the patent claims, even if said feature or said combination is itself not explicitly specified in the patent claims or exemplary embodiments.
Number | Date | Country | Kind |
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103 61 790.6 | Dec 2003 | DE | national |