Connection substrate, optoelectronic component and method for producing a connection substrate or an optoelectronic component

Abstract

The invention relates to a connection substrate (10) comprising • - a main body (1) which is formed with a plastic material, • - a conductor track (2) which has a bottom surface (2a) facing the main body (1), a top surface (2b) facing away from the main body (1), and a side surface (2c) connecting the bottom surface (2a) and the top surface (2b), wherein • - the conductor track (2) is in direct contact with the main body (1) at the base surface (2a) and the side surface (2c). The connection substrate can be used, for example, in an optoelectronic component which has a micro-LED (3).

Description

[0001] Description

[0002] CONNECTION CARRIER, OPTOELECTRONIC COMPONENT AND METHOD FOR PRODUCING A CONNECTION CARRIER OR A

[0003] OPTOELECTRONIC COMPONENT

[0004] A connection carrier, an optoelectronic component and a method for producing a connection carrier or an optoelectronic component are specified.

[0005] One problem to be solved is to provide a connection carrier and an optoelectronic component that are particularly mechanically stable. Another problem to be solved is to provide a corresponding manufacturing method.

[0006] According to at least one embodiment, the connection carrier comprises a base body. The base body is, in particular, the mechanically supporting component of the connection carrier, to which further components of the connection carrier can be mechanically fastened.

[0007] The base body can be designed, for example, as a rigid plate or flexible film. For example, the base body has a cuboid shape. The base body is formed from a plastic material. This means that the base body can contain the plastic material or consist of it.

[0008] According to at least one embodiment, the connection carrier comprises a conductor track. The conductor track is an electrically conductive structure formed from an electrically conductive material, such as a metal.

[0009] The conductor track can be cuboid-shaped, at least in sections. The conductor track runs, for example, along a straight and / or curved line. In particular, it is possible for the conductor track to be elongated. Furthermore, it is possible for the conductor track to have at least one bend, so that the direction in which the conductor track runs can change along its course.

[0010] The conductor track can serve to distribute electrical current on the connection carrier. Furthermore, and in particular, the conductor track can additionally serve as a contact point to which a component is mechanically and electrically attached.

[0011] The conductor track has a bottom surface facing the base body, a top surface facing away from the base body, and a side surface connecting the bottom surface and the top surface. It is possible for the conductor track to comprise several such side surfaces.

[0012] Furthermore, it is possible for the connection carrier to comprise two or more conductor tracks that are similar to one another, for example made from the same material within the manufacturing tolerance and have the same thickness within the manufacturing tolerance. The thickness is measured in a vertical direction that runs perpendicular to the main direction of extension of the connection carrier. In particular, it is possible for the thickness of the conductor track to be small compared to its extension in a main direction of extension of the conductor track. According to at least one embodiment of the connection carrier, the conductor track is in direct contact with the base body and thus with the plastic material of the base body on the bottom surface and the side surface. This means that the conductor track is in direct contact with the base body, for example, over the entire bottom surface.Furthermore, it is possible for one or all of the side surfaces of the conductor track to be in direct contact with the base body. The bottom surface and the side surface are, for example, wetted with the plastic material of the base body.

[0013] According to at least one embodiment, a connection carrier is specified with

[0014] - a base body made of a plastic material,

[0015] - a conductor track having a bottom surface facing the base body, a top surface facing away from the base body and a side surface connecting the bottom surface and the top surface, wherein

[0016] - the conductor track on the bottom surface and the side surface is in direct contact with the base body.

[0017] The conductor track can, for example, have a small width of in particular at most 10 pm, measured in a main extension plane of the connection carrier. Alternatively or additionally, it is possible for the conductor track to have a thickness of in particular at most 500 pm or at most 250 pm or at most 10 pm. In particular in the case of conductor tracks that are applied to a base body made of plastic, there are often only low connection forces between the conductor track and the base body. This is all the more the case for thin conductor tracks with a small width, which correspondingly have a base area with a small surface area.

[0018] If electronic components are attached to these conductor tracks, shear forces that can occur due to encapsulation or lamination, or temperature fluctuations, prove critical, as they can cause at least part of the conductor track to detach from the base body. Due to this limitation, it is not possible, for example, to encapsulate LED chips attached to such a connection carrier using an injection molding process.

[0019] The connection carrier described here makes use of the idea that direct contact between the conductor track and the base body, not only on the bottom surface but also on the side surface of the conductor track, leads to better anchoring of the conductor track in the base body. This means that shear forces that occur can no longer lead to the conductor track detaching from the base body, or only with a reduced probability. Furthermore, the temperature during application of the metallic conductor tracks is limited by the base body, since PET, for example, has only limited temperature stability. This leads to suboptimal adhesion of the conductor tracks to such substrates.

[0020] According to at least one embodiment of the connection carrier, the lateral surface is at least 50% or more, in particular completely, covered by the base body and thus, for example, with the plastic material of the base body, while the cover surface of the conductor track remains free from the base body and thus, for example, from the plastic material. In this way, the conductor track can be particularly securely anchored in the base body without the plastic material on the cover surface of the conductor track making it difficult to connect electronic components to the conductor track.

[0021] According to at least one embodiment of the connection carrier, the conductor track is printed onto the base body. The connection carrier can then be, in particular, a printed conductor track. The connection carrier can be designed to be flexible overall, for example, as a film, and can be formed by a printed circuit board.

[0022] According to at least one embodiment, the base body is designed to be radiation-permeable. The base body can be designed to be permeable, in particular, to electromagnetic radiation in the wavelength range between infrared light and UV radiation, in particular to visible light. For example, the base body is designed to be permeable to visible light and / or infrared radiation.

[0023] Such a connection carrier is particularly suitable for connecting light-emitting diodes and, for example, for the formation of translucent or transparent displays.

[0024] According to at least one embodiment of the connection carrier, the conductor track contains copper or is made of copper. Such conductor tracks can be applied to the base body in a particularly simple manner, for example by printing, and benefit particularly from the better anchoring of the conductor track in the base body due to the partial coverage of the side surface with material of the base body.

[0025] According to at least one embodiment of the connection carrier, a plurality of conductor tracks is applied to the base body. Using the plurality of conductor tracks, it is possible, for example, to mechanically attach a plurality of electronic components to the connection carrier and electrically connect them there.

[0026] According to at least one embodiment of the connection carrier, it is possible for the conductor tracks to be arranged in a network-like manner, at least in places. This means that the different conductor tracks can, in particular, intersect or cross each other. The conductor tracks on the upper side of the base body can, for example, form a network-like pattern in which a plurality of conductor tracks extend parallel to one another along a first direction and a plurality of conductor tracks extend along a second direction that runs transversely or perpendicularly to the first direction.

[0027] An optoelectronic component is also specified. The optoelectronic component described here comprises, in particular, a connection carrier described here, so that all features disclosed for the connection carrier are also disclosed for the optoelectronic component and vice versa.

[0028] According to at least one embodiment of the optoelectronic component, the optoelectronic component comprises an optoelectronic component which is mechanically and electrically conductively connected to the connection carrier on the cover surface of the conductor track.

[0029] For example, it is possible for the optoelectronic component to be mechanically and electrically connected to the connection carrier by soldering, i.e., by a solder material arranged between the optoelectronic component and the conductor track. Alternatively, a conductive adhesive can be arranged between the optoelectronic component and the conductor track.

[0030] In particular, the optoelectronic component then comprises a large number of components which are connected by a large number of conductor tracks.

[0031] The optoelectronic component can, for example, be a radiation-emitting component such as a laser diode or a light-emitting diode. Furthermore, the optoelectronic component can be a detecting component such as a photodiode.

[0032] According to at least one embodiment of the optoelectronic component, the optoelectronic component is a micro-LED or mini-LED or comprises a micro-LED or a mini-LED.

[0033] As a broad definition, a micro-LED can be seen as any light-emitting diode (abbreviated to "LED") - generally not a laser - with a particularly small size.

[0034] As a rule—an important criterion alongside size—micro-LEDs have a growth substrate removed, so typical heights of such micro-LEDs range from 1.5 pm to 10 pm, inclusive. In contrast, mini-LEDs still have the growth substrate attached, resulting in a thickness of approximately 50–100 pm.

[0035] In principle, a micro-LED does not necessarily have to have a rectangular radiation emission surface. For example, an LED with a radiation emission surface can generally be used in which, in a top view of the layers of the layer stack, each lateral extent of the radiation emission surface is less than or equal to 100 pm or less than or equal to 70 pm, inclusive.

[0036] For example, for rectangular micro-LEDs, an edge length of less than or equal to 70 pm or less than or equal to 50 pm is often cited as a criterion - especially in plan view of the layers of the layer stack.

[0037] Such micro-LEDs are usually provided on wafers.

[0038] The main application of micro-LEDs is currently displays. Micro-LEDs form pixels or subpixels and emit light of a defined color. Due to their small pixel size and high density with close spacing, micro-LEDs are suitable for small monolithic displays for AR applications, particularly data glasses. In addition, work is being done on other applications, particularly data communications and pixelated lighting applications. Various notations for micro-LEDs can be found in the literature, e.g. pLED, p-LED, uLED, u-LED or Micro Light Emitting Diode.

[0039] Furthermore, a method for producing a connection carrier or an optoelectronic component is specified. By means of the method described here, in particular, the connection carriers and optoelectronic components described here can be produced. This means that all features disclosed for the connection carrier and the optoelectronic component are also disclosed for the method, and vice versa.

[0040] According to at least one embodiment of the method, a base body formed from a plastic material is provided. The base body is, for example, a plate, which may be rigid, or a film, which may be flexible.

[0041] According to at least one embodiment, a conductor track is applied to an upper side of the base body. In particular, a plurality of conductor tracks are applied to the upper side of the base body. For example, the conductor tracks are attached to the upper side of the base body by a printing process.

[0042] According to at least one embodiment of the method, the conductor track is heated so that, by means of heat transfer from the conductor track to the base body, the plastic material of the base body softens in the vicinity of the conductor track and the conductor track sinks into the base body or the

[0043] The base body surrounds it. In this way, a side surface of the conductor track can be brought into direct contact with the base body, so that the conductor track is in direct contact with the base body at its bottom surface, which faces the base body, and at its side surface, which connects the bottom surface to a top surface of the conductor track facing away from the bottom surface. The top surface remains free of the material of the base body.

[0044] According to at least one embodiment, a method for producing a connection carrier or an optoelectronic component is specified, comprising the steps of:

[0045] - Providing a base body formed with a plastic material,

[0046] - applying a conductor track, which has a bottom surface facing the base body, a top surface facing away from the base body and a side surface connecting the bottom surface and the top surface, to an upper side of the base body,

[0047] - Heating the conductor track so that, by means of heat transfer from the conductor track to the base body, the plastic material of the base body in the vicinity of the conductor track softens and the conductor track is surrounded by the base body, in particular laterally, which leads to an increase in adhesion.

[0048] These procedural steps can, for example, be carried out in the order given.

[0049] The process is based, among other things, on the consideration that the conductor track is selectively heated, and any softening, such as melting or melting of the base material, occurs only indirectly via the conductor track. In this way, the base body is subjected to minimal thermal stress and, in particular, is not softened, melted, or melted over its entire surface.

[0050] In this way, it is possible, for example, to retain an optical property of the base body, such as transparency in the visible range of the electromagnetic spectrum. Furthermore, the base body's material and shape remain unchanged. For example, there is no shrinkage due to heating of the base body.

[0051] This means that the selective heating of the conductor track barely increases the overall temperature of the substrate. However, locally, where the substrate is in direct contact with the conductor track, heating occurs above the glass transition temperature or even above the melting temperature of the substrate's plastic material.

[0052] According to at least one embodiment of the method, heating is carried out by means of pulsed electromagnetic radiation to which the base body is permeable.

[0053] For example, heating is carried out with the aid of flash light, which can be generated using a xenon lamp, for example. The pulsed electromagnetic radiation is absorbed in the conductor track and causes it to heat up there. The base body is largely permeable to the radiation and has, for example, a transparency of greater than 90%. In this way, there is little or no heating of the base body by the electromagnetic radiation. The method makes it possible in particular to heat a large number of conductor tracks simultaneously and to increase adhesion to the base body in the manner described. For example, it is possible for the conductor tracks to sink into the base body and / or for a bulge made of material from the base body to form around the conductor tracks.

[0054] According to at least one embodiment of the method, an optoelectronic component is attached to the top surface of the conductor track prior to heating the conductor track, with the optoelectronic component being mechanically and electrically connected to the top surface simultaneously with the heating. For this purpose, a connecting material such as soldering material can be arranged between the top surface and the optoelectronic component, which is melted upon heating.

[0055] This means, for example, that the component can be soldered on at the same time as the adhesion of the conductor track to the base body is improved. The result is an optoelectronic component in which, during a stress test under the influence of shear forces, the optoelectronic component detaches from the conductor track more quickly than the conductor track detaches from the base body. This means that the anchoring of the conductor track in the base body is mechanically more stable than the soldered connection between the component and the conductor track. This results in a particularly mechanically stable component.

[0056] As an alternative to the described method, it is also possible to first manufacture the connection carrier in the manner described, followed by attaching the optoelectronic component to the connection carrier. In this case, the mechanical and electrical connection can be achieved using an adhesive process as an alternative to soldering. Furthermore, it is possible to heat the conductor track by selectively sweeping a laser beam over it, which heats the conductor track in a targeted manner.

[0057] In the following, the connection carrier described here, the optoelectronic component described here and the methods described here are explained in more detail using exemplary embodiments and the associated figures.

[0058] A first embodiment of a method described here is explained in more detail using the schematic sectional views in Figures 1, 2, 3, 4.

[0059] An embodiment of an optoelectronic component described here is explained in more detail using the schematic sectional view in Figure 4.

[0060] A further embodiment of a method described here is explained in more detail using the schematic sectional representation of Figures 5, 6 and 7.

[0061] An embodiment of an optoelectronic component described here and an embodiment of a connection carrier described here are explained in more detail with reference to the schematic plan view in Figure 8.

[0062] Identical, similar or functioning elements are provided with the same reference symbols in the figures. The figures and the proportions of the elements shown in the figures are not to be regarded as being to scale. Rather, individual elements may be displaced for the purpose of better illustration and / or for a better

[0063] For clarity, the text may be exaggerated.

[0064] Figure 1 shows a schematic sectional view of a base body 1. The base body 1 is formed from a plastic material such as PET. The base body 1 can be formed, for example, as a film and is largely permeable to visible light, for example, transparent.

[0065] Conductor tracks 2 are arranged on an upper side 1a of the base body 1. The conductor tracks 2 each comprise a bottom surface 2a facing the base body, a cover surface 2b facing away from the bottom surface 2a, and a side surface 2c connecting the cover surface and the bottom surface.

[0066] The conductor tracks 2 are formed, for example, with copper and have a width d of at most 500 pm, in particular of at least 5 pm and at most 60 pm (see also Figure 8).

[0067] A further method step is shown in connection with Figure 2. In this method step, the conductor tracks 2 are heated by means of electromagnetic radiation 6 generated by a radiation source 5.

[0068] The radiation source 5 is, for example, a xenon flash lamp, and the electromagnetic radiation 6 is corresponding light. The electromagnetic radiation 6, which is absorbed predominantly in the conductor tracks 2, but not in the base body 1, which is permeable to the electromagnetic radiation 6, heats the conductor tracks 2. Regions of the base body 1 in the immediate vicinity of the conductor tracks 2 are heated to a temperature that is higher than the glass transition temperature of the plastic material of the base body 1.

[0069] As schematically illustrated in the sectional view of Figure 3, the conductor tracks 2 sink into the base body 1 in such a way that, in addition to the bottom surface 2a of the conductor tracks 2, the side surfaces 2c of the conductor tracks 2 are now also in direct contact with the base body. Alternatively or in addition to the sinking, a bead of material of the base body can form on the side surfaces 2c.

[0070] In a next method step (Figure 4), an optoelectronic component 3 can be mechanically and electrically fastened to the connection carrier 10 by means of a connecting material 4. The connecting material 4 can be a soldering material or an electrically conductive adhesive. The optoelectronic component 3 can, in particular, be a light-emitting diode, for example a micro-LED.

[0071] Based on the alternative embodiment of the method illustrated in the schematic sectional views of Figures 5, 6 and 7, a method is described in which the connection carrier 10 and the optoelectronic component 20 are manufactured simultaneously. For this purpose, the optoelectronic component 3 is applied to the cover surface 2b of the conductor tracks before heating, with a precursor of the connecting agent 4 being introduced between the component 3 and the conductor tracks 2. For example, this is a solder paste that is introduced between the component 3 and the conductor track 2.

[0072] In the subsequent process step, Figure 6, the conductor tracks and the connecting means are heated simultaneously, so that the mechanical and electrical connection of the optoelectronic component on the cover surface takes place at the same time as the heating of the conductor track.

[0073] This again results in an optoelectronic component as shown in Figure 7.

[0074] The schematic top view of Figure 8 shows a connection carrier 10 in which a plurality of conductor tracks 2 are applied in a network-like manner to the base body 1. The side surfaces 2c of the conductor tracks 2 are each wetted by material of the base body 1, while the top surface 2b of the conductor tracks 2 remains free of material of the base body. Furthermore, the optoelectronic component 3 is attached to the connection carrier 10 by means of the connecting material 4.

[0075] The invention is not limited to the embodiments by the description thereof. Rather, the invention encompasses every novel feature and every combination of features, including in particular every combination of features in the patent claims, even if this feature or combination itself is not explicitly stated in the patent claims or embodiments. This patent application claims priority from German patent application 102023116887.8, the disclosure of which is hereby incorporated by reference.

[0076] Reference symbol list

[0077] 1 Base body la top side 2 Conductor track

[0078] 2a Floor area

[0079] 2b Cover surface

[0080] 2c side surface

[0081] 3 optoelectronic component 4 connecting material

[0082] 5 Radiation source

[0083] 6 electromagnetic radiation

[0084] 10 connection carrier 20 optoelectronic component d width

Claims

Patent claims 1. Connection carrier (10) with - a base body (1) formed with a plastic material, - a conductor track (2) which has a bottom surface (2a) facing the base body (1), a cover surface (2b) facing away from the base body (1) and a side surface (2c) connecting the bottom surface (2a) and the cover surface (2b), wherein - the conductor track (2) is in direct contact with the base body (1) on the bottom surface (2a) and the side surface (2c).

2. Connection carrier (10) according to the preceding claim, in which the side surface (2c) is at least 50% or completely covered with the plastic material and the cover surface (2b) is free of the plastic material.

3. Connection carrier (10) according to one of the preceding claims, in which the conductor track (2) is printed on the base body.

4. Connection carrier (10) according to one of the preceding claims, in which the base body (1) is radiation-permeable.

5. Connection carrier (10) according to one of the preceding claims, in which the conductor track (2) contains copper or consists of copper.

6. Connection carrier (10) according to one of the preceding claims with a plurality of conductor tracks (2).

7. Connection carrier (10) according to one of the preceding claims with a plurality of conductor tracks (2) which are arranged in a network.

8. Optoelectronic component (20) with - a connection carrier (10) according to one of the preceding claims and - an optoelectronic component (3) which is mechanically and electrically connected to the connection carrier (10) on the cover surface (2b) of the conductor track (2).

9. Optoelectronic component (20) according to the preceding claim, wherein the optoelectronic component (3) is or comprises a micro or mini-LED.

10. Method for producing a connection carrier (10) or an optoelectronic component (20) comprising the steps of: - Providing a base body (1) formed with a plastic material, - Applying a conductor track (2) which has a (1) facing the base body (1), a cover surface (2b) facing away from the base body (1) and a side surface (2c) connecting the base surface (2a) and the cover surface (2b), on an upper side (la) of the base body (1), - Heating the conductor track (2) so that by means of Heat transfer from the conductor track (2) to the base body (1) the plastic material of the base body (1) softens in the vicinity of the conductor track (2) and the conductor track (2) has improved adhesion to the base body (1).

11. Method according to the preceding claim, wherein the heating is carried out by means of pulsed electromagnetic radiation to which the base body (1) is permeable.

12. Method according to one of the preceding claims, in which a plurality of conductor tracks (2) are heated simultaneously.

13. Method according to one of the preceding claims, in which an optoelectronic component (3) is attached to the cover surface (2b) of the conductor track (2) before heating the conductor track (1), wherein a mechanical and electrical connection of the optoelectronic component (3) to the cover surface (2b) takes place simultaneously with the heating of the conductor track (2).

14. Method according to the preceding claim, in which a connecting material (4) arranged between the cover surface (2b) and the optoelectronic component (3) is melted during heating.

15. Method according to one of the preceding claims, in which a connection carrier (10) according to claims 1 to 7 or an optoelectronic component (20) according to claims 8 or 9 is produced.

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