WO2025002824A1 - Connection substrate, optoelectronic component and method for producing a connection substrate or an optoelectronic component - Google Patents

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

Description

CONNECTION CARRIER, OPTOELECTRONIC COMPONENT AND METHOD FOR PRODUCING A CONNECTION CARRIER OR A

OPTOELECTRONIC COMPONENT

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

One problem to be solved is to specify a connection carrier and an optoelectronic component that are particularly mechanically stable. A further problem to be solved is to specify a corresponding method for manufacturing.

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.

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

According to at least one embodiment, the connection carrier comprises a conductor track. The conductor track is an electrically conductive structure which is connected to a electrically conductive material such as a metal.

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. It is also 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.

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

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.

It is also possible for the connection carrier to comprise two or more conductor tracks that are designed similarly to one another, i.e., for example, are made of 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 extension direction 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 extension direction 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 over the entire bottom surface, for example. It is also possible for one side surface or possibly all side surfaces of the conductor track to be in direct contact with the base body. The bottom surface and the side surface are wetted with the plastic material of the base body, for example.

According to at least one embodiment, a connection carrier is provided with

- a base body made of a plastic material,

- a conductor track having a bottom surface facing the base body, a cover surface facing away from the base body and a side surface connecting the bottom surface and the cover surface, wherein

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

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. Particularly in the case of conductor tracks that are applied to a base body made of plastic, there are often only low connecting forces between the conductor track and the base body. This is even more the case with thin conductor tracks with a small width, which accordingly have a base area with a small surface area.

If electronic components are attached to these conductor tracks, shear forces that can occur due to encapsulation or lamination or temperature fluctuations prove to be critical, as this 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 light-emitting diode chips that are attached to such a connection carrier using an injection molding process.

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 and thus, in particular, shear forces that occur no longer lead to the conductor track detaching from the base body or only do so with reduced probability. Furthermore, the temperature when applying the metallic conductor tracks is limited by the base body because PET, for example, has only limited temperature stability. This leads to suboptimal adhesion of the conductor tracks to such substrates.

According to at least one embodiment of the connection carrier, the side surface is at least 50% or more, in particular completely, connected to the base body and thus, for example, to the plastic material of the base body, whereby the top 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 anchored particularly firmly in the base body without the plastic material on the top surface of the conductor track making it difficult to connect electronic components to the conductor track.

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

According to at least one embodiment, the base body is designed to be permeable to radiation. 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.

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

According to at least one embodiment of the connection carrier, the conductor track contains copper or the conductor track 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 strongly from the Better anchoring of the conductor track in the base body due to partial coverage of the side surface with material of the base body.

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

According to at least one embodiment of the connection carrier, it is possible for the conductor tracks to be arranged in a net-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 net-like pattern in which a large number of conductor tracks extend parallel to one another along a first direction and a large number of conductor tracks extend along a second direction that runs transversely or perpendicularly to the first direction.

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.

According to at least one embodiment of the optoelectronic component, the optoelectronic component comprises an optoelectronic component which is mounted on the cover surface of the Conductor track is mechanically and electrically connected to the connection carrier.

For example, it is possible for the optoelectronic component to be mechanically and electrically connected to the connection carrier by soldering and thus by a soldering 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.

In particular, the optoelectronic component then comprises a large number of components which are connected to a large number of conductor tracks.

The optoelectronic component can be, for example, a radiation-emitting component such as a laser diode or a light-emitting diode. It is also possible that the optoelectronic component is a detecting component such as a photodiode.

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.

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.

As a rule - this is also an important criterion besides the size - a growth substrate is removed from micro-LEDs, so that typical heights of such micro-LEDs are, for example, in the range of 1.5 pm to 10 pm, including limits. Mini-LEDs, in contrast, still have the growth substrate attached, resulting in a thickness of approx. 50 - 100 pm.

In principle, a micro-LED does not necessarily have to have a rectangular radiation emission surface. In general, for example, an LED with a radiation emission surface can be used in which, in a plan view of the layers of the layer stack, each lateral extension of the radiation emission surface is less than or equal to 100 pm or less than or equal to 70 pm, including boundaries.

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

Most of the time, such micro-LEDs are provided on wafers.

The main applications for micro-LEDs are currently displays. The micro-LEDs form pixels or subpixels and emit light of a defined color. Due to the small pixel size and high density with a small spacing, micro-LEDs are suitable for small monolithic displays for AR applications, especially data glasses. In addition, work is being done on other applications, in particular data communication or pixelated lighting applications. In the literature you can find different spellings for micro-LED, e.g. pLED, p-LED, uLED, u-LED or Micro Light Emitting Diode.

A method for producing a connection carrier or an optoelectronic component is also specified. The method described here can be used to produce connection carriers and optoelectronic components described here in particular. This means that all features disclosed for the connection carrier and the optoelectronic component are also disclosed for the method and vice versa.

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

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 means of a printing process.

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

basic body that 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 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.

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

- Providing a base body formed with a plastic material,

- 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,

- 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, particularly laterally, which leads to an increase in adhesion.

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

The process is based, among other things, on the consideration that the conductor track is selectively heated and softening, for example melting or melting of the material of the base body, only takes place indirectly via the conductor track. In this way, the base body is hardly subjected to thermal stress and in particular is not softened, melted or melted over its entire surface.

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 is not changed in terms of material or shape. For example, there is no shrinkage due to heating of the base body.

This means that the overall temperature of the base body is hardly increased by selectively heating the conductor track. However, locally, where the base body is in direct contact with the conductor track, heating occurs above the glass transition temperature or even above the melting temperature of the plastic material of the base body.

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.

For example, heating is carried out using flashlight, which can be generated using a xenon lamp, for example. The pulsed electromagnetic radiation is absorbed in the conductor track and leads to heating there. The base body is largely permeable to the radiation and has a transparency of more than 90% for the radiation, for example. In this way, the base body is hardly or not at all heated by the electromagnetic radiation. The method makes it possible in particular to heat a large number of conductor tracks simultaneously and to increase the 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 bead of material from the base body to form around the conductor tracks.

According to at least one embodiment of the method, an optoelectronic component is attached to the cover surface of the conductor track before heating the conductor track, wherein a mechanical and electrical connection of the optoelectronic component to the cover surface takes place at the same time as heating. For this purpose, for example, a connecting material such as a soldering material can be arranged between the cover surface and the optoelectronic component, which is melted when heated.

This means, for example, that the component can be soldered on at the same time as the adhesion of the conductor track in 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 is more likely to detach from the conductor track than the conductor track 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.

As an alternative to the method described, it is also possible to first produce the connection carrier in the manner described and then attach the optoelectronic component to the connection carrier. The mechanical and electrical connection can then As an alternative to soldering, the process can also be carried out using an adhesive process. It is also possible to heat the conductor track by passing a laser beam over it in a targeted manner, which specifically heats the conductor track.

In the following, the connection carrier described here, the optoelectronic component described here and the methods described here are explained in more detail using embodiment examples and the associated figures.

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

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

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

An embodiment of an optoelectronic component described here and an embodiment of a connection carrier described here are explained in more detail using the schematic plan view in Figure 8.

Identical, similar or similarly acting 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 can for better presentation and/or for better

For clarity, the text may be exaggerated.

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

Conductor tracks 2 are arranged on an upper side la of the base body 1. The conductor tracks 2 each comprise a bottom surface 2a, which faces the base body, a cover surface 2b facing away from the bottom surface 2a, and a side surface 2c, which connects the cover surface and the bottom surface to one another.

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).

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, which is generated by a radiation source 5.

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, causes the conductor tracks 2 to heat up. Regions of the base body 1 in the immediate vicinity of the conductor tracks 2 are heated to a temperature which is high compared to the glass transition temperature of the plastic material of the base body 1.

As shown schematically in the sectional view of Figure 3, this causes the conductor tracks 2 to 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 made of material from the base body can form on the side surfaces 2c.

In a next method step, Figure 4, an optoelectronic component 3 can be mechanically and electrically attached to the connection carrier 10 by means of a connecting material 4. The connecting means 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.

Based on the alternative embodiment of the method shown in the schematic sectional views of Figures 5, 6 and 7, a method is described in which the manufacture of the connection carrier 10 and the manufacture of the optoelectronic component 20 take place 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.

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.

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

The schematic top view of Figure 8 shows a connection carrier 10 in which a large number 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, the cover 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.

The invention is not limited to the embodiments by the description thereof. Rather, the invention encompasses any new feature and any combination of features, which in particular includes any combination of features in the patent claims, even if this feature or this 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 content of which is hereby incorporated by reference.

reference symbol list

1 Base body la top side 2 Conductor track

2a floor area

2b top surface

2c side surface

3 optoelectronic component 4 connecting material

5 radiation source

6 electromagnetic radiation

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, wherein 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, wherein 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) with the steps: - 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, in which 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.