FIGS. 15 and 16 particularly show a top view and a cross-sectional view respectively according to a second embodiment of the invention in which the electronic component is perpendicularly aligned with its corresponding pictogram.

FIG. 17 shows a top view of the first sheet after step d) wherein the detail I corresponding to an electrical pad is surrounded.

FIG. 18 shows a schematic enlarged view of the detail I represented in the FIG. 17.

FIG. 19 shows a top view of the first sheet after step i) wherein a light management material affecting the light emitted by the lighting device is schematically represented.

FIG. 20 shows a cross-sectional view of the trim panel according to an embodiment of the invention in which the shape of the decorative covering matches with the shape of the shape of the first sheet.

FIG. 21 shows a schematic enlarged view of the detail J represented in the FIG. 20 according to a first embodiment.

FIG. 22 shows a schematic enlarged view of the detail J represented in the FIG. 20 according to a second embodiment.

FIG. 23 shows a cross-sectional view of the trim panel according to an embodiment of the invention in which the shape of the decorative covering partially matches with the shape of the shape of the first sheet.

FIG. 24 shows a perspective view of a trim panel according to the invention where some particular pictograms are represented.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 to 16 show a schematic view of the method for manufacturing trim panels (10) for vehicles having an electronic function through the components obtained in each step.

The method starts with the step a) represented in FIGS. 1 and 2. In this step a) it is provided a first sheet (1) comprising a flexible flat plastic film having a first area (1.1) being flat.

The plastic film includes a material selected from the group of polycarbonate (PC), Polymethyl methacrylate (PMMA), polyester (PE), polyethylene terephthalate (PET), polypropylene (PP), thermoplastic polyurethane (TPU).

The plastic film preferably comprises a thickness being between 50-750 μm.

The method continues with the step b) represented in FIGS. 3 and 4. In this step b) the first sheet (1) being flat, is printed with a first electrical conductive ink (6) for forming an electrical conductive track (2.1) at its first side (1.2).

Said electrical conductive track (2.1) printed during this step forms the first part of the electrical circuit (2).

In addition of the electrical conductive track (2.1), other parts forming the electrical circuit (2) can be printed during this step b), particularly other parts remaining at substantially flat areas of the first sheet (1) after the forming process of step c). Thus, said optional electrical parts, also form the first part of the electrical circuit (2).

The printing process of step b) comprises a two-dimensional printing process such as screen-printing, inkjet printing, flexographic, gravure or offset lithographic printing.

The first conductive ink (6) is specifically formulated in terms of materials and viscosity to favour both its compatibility with the first sheet (1) and to be applied by the two dimensional printing process.

It can comprise a dispersion of particles comprising a conductive metal, dispersed in a solvent. Said conductive metal can for example be silver, copper, a combination thereof, etc.

The dynamic viscosity of the first conductive ink (6) can vary in the range between 5,000 and 200,000 mPas at room temperature, being between 2° and 22° C.

After step b), the method continues with the step c) represented in FIGS. 5 and 6. In this step c) the first sheet (1) comprising the electrical conductive track (2.1), and optionally other parts forming the electrical circuit (2), is formed according to a three-dimensional shape in such a way that the first area (1.1) has a three-dimensional shape as FIG. 6 shows.

It means that the first area (1.1) is deformed and stretched during the forming step for adopting a three-dimensional shape. Said forming process can be carry out for example by thermoforming or by cold forming.

Then, the method continues with step d) represented in FIGS. 7 and 8. In this step d) an electrical conductive pad (2.2) configured to be connected to the electrical conductive track (2.1) is printed with a second conductive ink (7) on the first area (1.1) previously deformed, particularly on the first side (1.2) of the first sheet (1).

The printing process of step d) comprises a three-dimensional printing process, particularly, a fluid dispensing process or a pad printing process.

In case of fluid dispensing process, it can use an automated fluid dispenser fixed to a robot or automaton to dispense the second conductive ink (7) on the first sheet (1), and particularly on the first side (1.2) thereof.

Some examples of fluid dispensing technologies can be piezo jet valve dispensing, aerosol jet printing, 3D dispensing or pneumatic Spray.

In case of pad printing process, it can use a silicon pad for taking the second conductive ink (7) from an engraved printing plate called cliché, in order to transfer said second conductive ink (7) on the first sheet (1), and particularly on the first side (1.2) thereof.

The second conductive ink (7) is specifically formulated in terms of materials and viscosity to favour both its compatibility with the first sheet (1) and to be applied by the three dimensional printing process.

It can comprise a dispersion of particles comprising a conductive metal, dispersed in a solvent. Said conductive metal can for example be silver, copper, a combination thereof, etc.

Depending on the particular fluid dispensing technology or the pad printing process, the dynamic viscosity of the second ink can vary in the range between 1 and 1,000, 000 mPas at a room temperature, being between 2° and 22° C.

For example, in case of piezo jet valve dispensing the dynamic viscosity is in the range between 50-200,000 mPas, in the case of aerosol jet printing the dynamic viscosity is in the range between 1-20 mPas, in the case of 3D dispensing the dynamic viscosity in the range between 1-1,000, 000 mPas, in the case of pneumatic Spray the dynamic viscosity is in the range between 600-150,000 mPas, in the case of pad printing is in the range between 80-1,000 mPas.

According to a particular case, the first conductive ink (6) and the second conductive ink (7) are the same conductive ink. This results particularly advantageous since a single conductive ink is managed during the entire process.

The electrical conductive pad (2.2) can be directly connected to the electrical conductive track (2.1) in order to ensure the electrical continuity between both parts or it can be indirectly connected through an electrical intermediate portion (2.3) as it is represented in FIG. 18.

The electrical intermediate portion (2.3), if necessary, is printed by fluid dispensing or by pad printing during the step d).

Said electrical intermediate portion (2.3) can be convenient for example in case the path of the end of an electrical conductive track (2.1) diverts from the path originally defined as consequence of the stretching of the first sheet (1) suffered during the forming process as the detail of FIG. 18 shows.

In such case, the electrical conductive pad (2.2) printed according to a predefined target position, that is, the position being in correspondence with the corresponding pictogram (5.1) in the final trim part (10), is not connected to the electrical conductive track (2.1).

Therefore, the electrical intermediate portion (2.3) is printed to connect both parts (2.1, 2.2) and in this way ensuring the electrical continuity between them without modifying the position of the electrical conductive pad (2.2) according to the predefined target position thereof.

In addition, said electrical intermediate portion (2.3) can be convenient in case in which several electrical conductive pads (2.2) are very closed together.

In such a case, the corresponding electrical conductive tracks (2.1) are defined according to a shorter length than the necessary to connect each one with the corresponding electrical conductive pad (2.2). This is to avoid connection errors between an electrical conductive track (2.1) and a non-corresponding electrical conductive pad (2.2) which is very closed to the corresponding electrical conductive pad (2.2).

Thus, the electrical intermediate portion (2.3) would allow connecting said shorter electrical conductive track (2.1) with the corresponding electrical conductive pad (2.2) minimizing the risk of short circuit.

Optionally, the present invention also considers that said step d) can be used to print other portions of the electrical circuit such as an electrical conductive track (2.1) partly or completely, which are extended over a very deformed area of the first sheet (1) in order to ensure the integrity of said portions due to the fact that said portions are not subjected to the forming process of step c).

Additionally, this step d) can be used to correct errors produced in the first part of the electrical circuit (2) previously configured in the first printing step b) as a result of the stretching of the first sheet (1) during the forming step c).

Next step in the method comprises step e) represented in FIGS. 9 and 10. In this step e) an electronic component (3) is attached to the corresponding electrical conductive pad (2.2). Thus, the electronic component (3) can be powered by said electrical conductive pad (2.2).

For this attaching step, for example a pick-and-place device can be used. It comprises a robot used to place surface-mount devices (SMDs) onto a printed circuit. Said devices are characterized for high speed and high precision placing of a broad range of electronic components.

The electronic component (3) can be for example a lighting device such as a LED, a sensor, a resistor, a capacitor, an inductor, an antenna or a micro-controller.

Preferably, the first sheet (1) comprises several of them combined.

Regarding the attaching means, that is, the means responsible for ensuring the electronic component (3) attachment to the corresponding electrical conductive pad (2.2) during the following steps of the method, the invention considers several options.

One possible option is to attach the electronic component (3) directly to the electrical conductive pad (2.2). In this case, the electronic component (3) is attached to the electrical conductive pad (2.2) before the second electrical conductive ink (7) is cured in such a way that said second electrical conductive ink (7) additionally acts as an adhesive. Once it is cured, the attachment between both components (2.2, 3) is consolidated.

In order to improve the mechanical connection between both components (2.2, 3), a structural adhesive (9) can be deposited on the electronic component (3) after attaching it to the electrical conductive pad (2.2).

Other possible option shown in FIG. 21, is to attach the electronic component (3) by depositing a third electronic conductive ink (8) on the electrical conductive pad (2.2) once it is cured. Said third electrical conductive ink (8) allows electrically and mechanically connecting the electronic component (3) to the electrical conductive pad (2.2).

In order to improve the mechanical connection between both components (2.2, 3) according to this option, said third electrical conductive ink (8) can be structural.

Other option to improve the mechanical connection between both components (2.2, 3) shown in FIG. 22, is to deposit a structural adhesive (9) after attaching the electronic component (3) to the electrical conductive pad (2.2) by the third electronic conductive ink (8). This structural adhesive (9) at least is deposited around to the periphery of the electronic component (3), namely on its connection pinouts in order not to affect the electronic component (3) operation.

Structural term mentioned above for defining the structural adhesive (9) and to the third electrical conductive ink (8), means that said materials comprise particular mechanical properties to stand the mechanical and thermal stress produced during the subsequent injection process of step f).

Third electrical conductive ink (8) and/or structural adhesive (9) can be applied by fluid dispensing or pad printing processes.

In a case in which the electronic device (3) is particularly a lighting device such as a LED the method optionally can further comprise a step i) after the step e) comprising a step of printing a light management material (11) on said lighting device affecting the light emitted by said lighting device, as FIG. 19 shows.

Said light management material (11