FR3137528A1 - Molded electronic device and method for making a molded electronic device - Google Patents

Abstract

Molded electronic device (1) comprising: - a printed film (10), the printed film (10) comprising a film (12) and at least one printed layer (14, 16), the film (12) having an external face ( 12a) and an internal face (12b), - an electronic element (2) electrically connected to the electrically conductive layer (16), - a support layer (32, 42) extending on the internal face (12b) and stiffening the printed film (10), and - an external protective layer (22), the external protective layer (22) is transparent, made of crosslinked polyurethane and has an appearance face (22a) and a contact face (22b), the face appearance (22) has a shiny appearance and the external face (12b) of the film (12) has an arithmetic roughness greater than 200 nm. Figure for abstract: Figure 4

Description

Molded electronic device and method for making a molded electronic device Area of disclosure

The present disclosure relates to a method for producing a molded electronic device, as well as a molded electronic device. In particular, the present disclosure concerns the production of an electronic device using the technique called In-mold Electronic (IME).

State of the art

A molded electronic device is known comprising:
- a printed film, the printed film (being flexible and) comprising a film and at least one printed layer, the film having an external face and an internal face, the at least one printed layer comprising at least one electrically conductive layer arranged on the internal face,
- an electronic element electrically connected to the electrically conductive layer,
- a support layer extending on the internal face and stiffening the printed film, and
- an external protective layer, the external protective layer being transparent, made of crosslinked polyurethane and having an appearance face and a contact face, the contact face being facing the external face of the film, the appearance face being opposite to the contact face.

By "transparent" or "translucent" is meant the fact that an element, in this case the external protective layer, has a light transmission rate greater than 5%, for example greater than 50%, in particular equal to 100% . By transparent we mean an element that does not diffuse light and translucent an element that diffuses light.

The presence of the electrically conductive layer and the production of the support layer on the printed film generates defects on the external face of the printed film. The higher the specular reflection (shininess), the more visible the defects. The defects consist of small asperities, geometric variations of the external face of the order of 1 to 100 microns corresponding to discontinuities in the printed layer and/or the support layer due in particular to the local presence of the electronic element.

Disclosure Statement

According to the disclosure, the molded electronic device has the following characteristics:
- the appearance face has a shiny appearance, and
- the external face of the film has an arithmetic roughness greater than 200 nm (compared to the shiny appearance of the appearance face).

The roughness of the external face of the film gives a matte appearance to the external face of the film, it is not necessary to act on the appearance side to conceal the defects on the external face of the film. In addition, the appearance face having a shiny appearance, the aesthetic possibilities of the electronic device are increased.

Brightness means specular bending according to ISO 2813 or ASTM D523, a standardized light source projecting a beam of light onto a surface with a tilt angle of 60 degrees relative to the surface normal and a detector being located to receive the reflected rays. The surface is said to be "glossy" or "high gloss" when the measurement is greater than 70 UB (Gloss Unit), "medium gloss" when the measurement is between 20 UB and 70 UB, and "matte" or "low gloss" when the measurement is less than 20 UB.

A gloss measuring device as defined above, called a gloss meter, is for example marketed under the reference Novo-Gloss Trio® by the company Rhopoint Instruments Ltd.

The shiny appearance of the appearance face can be obtained by low roughness, for example roughness Ra (arithmetic roughness) less than 15 nm (nanometers). The average glossy appearance can be obtained by an average roughness, for example roughness Ra (arithmetic roughness) between 15 nm (nanometers) and 200 nm (nanometers). The matte appearance can be obtained by high roughness, for example roughness Ra (Arithmetic roughness) greater than 200 nm (nanometers).

According to another characteristic in accordance with the disclosure, preferably the appearance face presents:
- a shiny portion having a shiny appearance (at least with regard to the high roughness of the external face of the film), and
- a medium shiny portion having a medium shiny appearance.

According to an alternative characteristic in accordance with the disclosure, preferably the appearance face presents:
- a shiny portion having a shiny appearance (at least with regard to the high roughness of the external face of the film), and
- a matte portion having a matte appearance.

According to another alternative characteristic in accordance with the disclosure, preferably the appearance face presents:
- a shiny portion having a shiny appearance (at least with regard to the high roughness of the external face of the film),
- a medium-shiny portion having a medium-shiny appearance, and
- a matte portion having a matte appearance.

Thus, the appearance face can have different levels of gloss to adapt to the difficulty of masking the defects of the external face of the film or to create variations in visual appearance or variations in tactile sensation of the molded electronic device.

In accordance with the disclosure, preferably the molded electronic device preferably has the following characteristics:
- the appearance face extends between a first end and a second end, and
- the brightness of the appearance face decreases according to at least 3 levels, preferably at least 5 levels, from the first end to the second end.

According to a complementary characteristic in accordance with the disclosure, the brightness of the appearance face decreases strictly (presents a decreasing gradient over the entire appearance face between the first end towards the second end) from the first end towards the second end.

According to another characteristic in accordance with the disclosure, the support layer preferably comprises an opaque layer.

By "opaque" we mean the fact that an element, in this case the opaque layer, has a light transmission rate of less than 5%, for example 0%.

Thus, the opaque layer stiffens the printed film and prevents light from escaping from the internal side of the electronic device. The opaque layer is preferably also reflective, for example to reflect light into the transparent layer and/or towards the film, for example towards an element to be backlit.

According to another characteristic in accordance with the disclosure, the molded electronic device preferably comprises a transparent layer extending on the internal face and coming into contact with the electronic element.

The transparent layer serves as a light guide, thus enabling light to be transmitted, for example from a light source to an area of the film to be backlit. The transparent layer also allows for better homogeneity of light. The transparent layer can act as a support layer, or at least belong to the support layer, if the transparent material is rigid. If the transparent layer is flexible, the molded electronic device further comprises the support layer, distinct from the transparent layer.

By "flexible" we mean the fact that an element, in this case the printed film, is made of such a material, and with such dimensions, that the element, taken in isolation, can deform under its own weight when It is placed on two supports arranged at its farthest ends.

By "rigid" we mean the fact that an element, in this case the support layer, is made of such a material, and with dimensions such, that the element does not deform under the effect of the mechanical stresses applied. under normal conditions of use. In particular, the subassembly formed by the printed film and the support layer does not exhibit any perceptible deformation when a force of 5 Newton is applied to the printed film in line with the support layer. In other words, the printed film is stiffened by the support layer.

The electronic element is preferably a light source or a screen. The light source is in particular a diode, for example a light-emitting diode (LED). The screen is in particular an LCD screen, an OLED screen or a micro-LED matrix. Alternatively, the electronic element is a microcontroller, capacitor, LED driver module, multiplexer or amplifier.

The disclosure further relates to a method for producing a molded electronic device. According to the disclosure, the method comprises the following operations:
a) supply of a printed film and an electronic element, the printed film comprising a film and at least one printed layer, the film having an external face and an internal face, the external face having an arithmetic roughness greater than 200 nm , the at least one printed layer comprising at least one electrically conductive layer disposed on the internal face, the electronic element is electrically connected to the electrically conductive layer, then
b) production by injection of a support layer on the internal face, the support layer being configured to stiffen the printed film, then
c) injection and crosslinking of polyurethane to form an external protective layer on the external face of the film, the external protective layer being transparent and having an appearance face and a contact face, the contact face being opposite the external face of the film, the appearance face being opposite the contact face and having a shiny appearance (at least with regard to the high roughness of the external face of the film).

By injection we mean production by injection molding. The injection of polyurethane after the production of the support layer makes it possible to compensate for the geometric defects of the external face of the film. Thus, the risk that the geometric defects of the external face of the film does not generate a geometric defect on the appearance face is reduced, much more effectively than when the external protective layer is produced before the support layer and/or when the external protective layer is laminated or glued to the external face of the film. In addition, adhesion with the film is thus encouraged.

Brief description of the figures

Other characteristics and advantages of the present disclosure will appear in the following detailed description, referring to the appended drawings in which:

represents a first operation for producing a molded electronic device,

represents a second operation for producing the molded electronic device,

represents a third operation for producing the molded electronic device,

represents the resulting molded electronic device.

Detailed description of the disclosure

Figures 1 to 3 illustrate the production of a molded electronic device 1 shown in the .

As illustrated in , a printed film 10 and an electronic element 2 are placed in a first mold 60. The printed wire 10 comprises a film 12, a decor layer 14 and an electrically conductive layer 16. The film 12 has an external face 12a and an internal face 12b. Decor layer 14 is optional. In the illustrated embodiment, the decoration layer 14 is placed on the internal face 12b of the film 12, between the film 12 and the electrically conductive layer 16. Alternatively or in addition, the decoration layer 14 could be placed on the external face 12a of film 12. The decor layer 14 is preferably opaque and serves in particular to mask certain elements and/or represent pictograms, patterns to be backlit or the like. The decoration layer 14 is produced by printing a decoration ink on the film 12. The electrically conductive layer 16 is placed on the internal face 12b. It should be understood by this expression that the electrically conductive layer 16 is disposed on the internal side of the film 12 (below the film 12 in Figures 1 to 4), but the electrically conductive layer 16 is not necessarily disposed directly on the internal face 12b. The electrically conductive layer 16 comprises at least one electrically conductive track, preferably multiple electrically conductive tracks electrically isolated from each other. The electrically conductive layer 16 is preferably produced by printing an electrically conductive ink (for example based on copper or silver) on the film 12.

The film 10 is flexible and has a thickness preferably between 50 microns and 750 microns.

The external surface 12a has a matt appearance conferred by a high grain 11 represented schematically by thick dashes, in the embodiment illustrated the entire external surface 12a. More precisely, the entire external surface 12a has an arithmetic roughness greater than 200 nm. Preferably, the external surface 12a of the film has a gloss of less than 30 UB, preferably between 10 UB and 20 UB.

By “grain” we must understand the surface state, the microscopic geometry of the surface. It is the grain that allows you to obtain a more or less strong shine. Schematically and simplistically, the finer the grain, the higher the shine. However, the amplitude of asperities is not the only characteristic that tends to increase the scattering in multiple directions of light reflection on a surface. Given the complexity of explaining the characteristics of the grain necessary to obtain a range of shine (notably regularity), reference is made to the shine conferred by the grain. The qualifiers applied to the term "grain" do not constitute technical characteristics, but allow each grain to be identified without having to refer to a long expression. Thus, for example the expression "fine grain" will be used to avoid having to refer to "grain giving the appearance face a shiny appearance" and "high grain" will be used to avoid having to refer to “grain giving the surface a matt appearance”.

The electronic element 2 is disposed on the internal face 12b of the film 12. The electrically conductive layer 16 is disposed between the film 12 and the electronic element 2. The electronic element 2 is electrically connected to the electrically conductive layer 16, of preferably several tracks of the electrically conductive layer 16. The electronic element 2 is a light source or a screen. The electronic element 2 may in particular comprise a diode, for example a light-emitting diode (LED). The screen is in particular an LCD screen, an OLED screen or a micro-LED matrix. Alternatively, the electronic element could be a microcontroller, capacitor, LES driver module, multiplexer or amplifier.

The first mold 60 has a first part 62, a second part 64 and a cavity 66. The decor layer 14 and the electrically conductive layer 16 are printed on the film 12 to produce the printed film 10. Then, the electronic element 2 is connected to the electrically conductive layer 16, for example by bonding. Then, the printed film 10 and the electronic element 2 are placed in the cavity 66 of the first mold 60, the external face 12a of the film 12 being placed against the first part 62 of the first mold 60. The electronic element 2 has an exterior surface, part of which rests against the internal face 12b of the film and the remainder defines an envelope surface 5 (in other words uncovered) exposed to the cavity 66. Part of the cavity 66 is left free around the electronic element 2 and a transparent material 30 is injected into it.

The transparent material 30 is preferably polycarbonate (PC), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene (ABS), a mixture of polycarbonate (PC) and polymethyl methacrylate (PMMA), polyamide (PA ), styrene-methyl methacrylate (SMMA), cyclo-olefin copolymer (COC) or styrene acrylonitrile (SAN). Preferably, the transparent material 30 is injected at a temperature of between 200 and 300°C and a pressure of 600 and 700 bar.

As illustrated in , an optional transparent layer 32 is thus produced on the internal face 12b of the film 12, more precisely on the electrically conductive layer 16. The transparent layer 32 covers the envelope surface 5 of the electronic element 2 and the electronic element 2.

The printed film 10, the electronic element 2 and the transparent layer 32 are then placed in a second mold 70. The second mold 70 has a first part 72, a second part 74 and a cavity 76. The external face 12a of the film 12 is placed in support against the first part 72 of the second mold 70. A part of the cavity 76 is left free, in particular around the transparent layer 32 and an opaque material 40 is injected there. The opaque material is preferably a thermoplastic, in particular polypropylene.

As illustrated in , an opaque layer 42 is thus formed formed by the opaque material 40 and covering the entire internal face 12b. In the illustrated embodiment, the opaque layer 42 completely covers the transparent layer 32 and is in contact with the transparent layer 32. Furthermore, the opaque layer 42 forms a single element (the opaque layer is in one piece). The opaque layer 42 is preferably reflective, for example white, to reflect the light towards the external face 12a of the film 12, in other words towards a user. Alternatively, the opaque layer 42 could not completely cover the transparent layer 32, for example to place a light source. In addition, a layer of air could be provided between the transparent layer 32 and the opaque layer 42 to guide the light over a greater distance.

Furthermore, the opaque layer 42 could only partially cover the internal face 12b of the film 12, in order to leave tracks or portions of tracks of the electrically conductive layer 16 accessible. Thus, it is possible to carry out more effective electrical control as a functional check of the electronic device 1. Such an electrical check can thus be carried out with test tips on the electronic device 1 produced. In addition, it is also possible to electrically interconnect the electronic device 1 with an electronic card by means of a connector.

In the embodiment described, the transparent layer 32 and the opaque layer 42 are both rigid and contribute to stiffening the printed film 10. The transparent layer 32 and the opaque layer 42 thus form a support layer.

The printed film 10, the electronic element 2, the transparent layer 32 and the opaque layer 42 are then placed in a third mold 80. The third mold 80 has a first part 82, a second part 84 and a cavity 86. The layer opaque 42 is placed against the second part 84 of the third mold 80. Part of the cavity 86 of the third mold 80 is left free between the external face 12a of the film 12 and a face 83 of the first part 82 of the third mold 80 The face 83 has a first portion 87, a second portion 88 and a third portion 89. The face 83 more precisely presents a grain which gradually increases from the first portion 87 to the third portion 89 passing through the second portion 88. A there , the grain of the first portion 87, the second portion 88 and the third portion 89 is schematized by dashes which are thicker as the grain is coarser. Polyurethane 20 is injected into the cavity 86 between the external face 12a and the face 83. The composition to form the injected polyurethane is well known and comprises in particular an isocyanate and a polyol which are reacted.

After crosslinking the polyurethane, as illustrated in , the electronic device 1 is thus produced. The electronic device 1 is for example a vehicle interior device, for example a motor vehicle. The electronic device 1 has an external protective layer 22 formed by crosslinked polyurethane 20. In the illustrated embodiment, the external protective layer 22 covers the entire external face 12a. Alternatively, the external protective layer 22 could cover only part of the external face 12a. The external protective layer 22 has an appearance face 22a and a contact face 22b, opposite each other. The appearance face 22a is intended to be placed facing the user and therefore visible to the user. The contact face 22b faces (and is in contact in the illustrated embodiment) the external face 12a of the film 12.

The appearance face has a shiny portion 23, a medium glossy portion 25 and a matte portion 27. The shiny portion 23 is formed by the contact between the polyurethane 20 and the first portion 87. The shiny portion 23 has a fine grain 24 giving the aspect face 22a a shiny appearance. More precisely, the shiny portion 23 preferably has a low roughness Ra (arithmetic roughness) of less than 15 nm. The fine grain 24 is shown schematically by fine dashes. The medium shiny portion 25 is formed by the contact between the polyurethane 20 and the second portion 88. The medium shiny portion 25 has a medium grain 26 giving the appearance face 22a a medium shiny appearance. More precisely, the average shiny portion 25 preferably has an average roughness Ra (arithmetic roughness) of between 15 nm and 200 nm. Medium grain 26 is represented by medium-thick dashes. The matte portion 27 is formed by the contact between the polyurethane 20 and the third portion 89. The matte portion 27 has a coarse grain 28 giving the appearance face 22a a matte appearance. More precisely, the matte portion 27 preferably has a high roughness Ra (arithmetic roughness) greater than 200 nm. The coarse grain 28 is schematized by thick dashes.

More precisely, the appearance face 22a extends between a first end 21 and a second end 29. the brightness of the appearance face 22a decreases strictly from the first end 21 towards the second end 29.

The external protective layer 22 contributes to reinforcing the rigidity of the electronic device 1, which can be particularly favorable when the support layer formed by the transparent layer 32 and the opaque layer 42 only partially covers the internal face 12a of the film 12.

The film 12 and the external protective layer 22 preferably have refractive indices differing from each other by at least 0.050. For example, the film 12 is made of polycarbonate (PC) and has a refractive index (in the visible spectrum at 23°C) of 1.586, while the transparent layer 30 is made of crosslinked polyurethane and has a refractive index (in the visible spectrum at 23°C) of 1.510.

Alternatively, the brightness of the appearance face 22a could exhibit a decrease in degrees (preferably at least three degrees and more preferably at least five degrees) from the first end 21 towards the second end 29.

Of course, the disclosure is in no way limited to the embodiment(s) described by way of illustration, not limitation. Thus, a primer layer could be made between the external face 12a and the contact face 22b, in order to promote the adhesion of the external protective layer 22 to the film 12.

Furthermore, in the illustrated embodiment, the external face 12a has a uniform grain, so that the external face 12a has a uniformly matte appearance. The external face 12a has a high roughness at least with respect to the shiny portion 23 presenting the fine grain 24 giving the appearance face 22a a shiny appearance. Although this is not preferred, the external face 12a may not have a high roughness compared to the matte portion 27 presenting the coarse grain 28 giving the appearance face 22a a matte appearance.

Conversely, the entire aspect face 22a could present the shiny appearance.

The external face 12a could then only present the arithmetic roughness greater than 200 nm locally, at the level of the asperities, in order to mask them.

The electronic device 1 could comprise several electronic elements 2.

The transparent layer 32 is optional, the opaque layer 42 could come directly into contact with the electronic element 2.

The first mold 60, the second mold 70 and the third mold 80 can be constituted by one or two devices whose cavity can be modified, for example by retracting walls or removing elements. In other words, the second mold 70 can be constituted by the first mold 60 in a different configuration and the third mold 80 can be constituted by the first mold 60 or the second mold 70 in a different configuration.

Claims (10)

Molded electronic device (1) comprising:
- a printed film (10), the printed film (10) comprising a film (12) and at least one printed layer (14, 16), the film (12) having an external face (12a) and an internal face (12b ), the at least one printed layer comprising at least one electrically conductive layer (16) arranged on the internal face (12b),
- an electronic element (2) electrically connected to the electrically conductive layer (16),
- a support layer (32, 42) extending on the internal face (12b) and stiffening the printed film (10), and
- an external protective layer (22), the external protective layer (22) being transparent, made of crosslinked polyurethane and having an appearance face (22a) and a contact face (22b), the contact face (22b) being made of view of the external face (12a) of the film (12), the appearance face (22a) being opposite the contact face (22b),
said molded electronic device (1) being characterized in that:
- the appearance face (22a) has a shiny appearance, and
- the external face (12b) of the film (12) has an arithmetic roughness greater than 200nm. Molded electronic device according to claim 1 in which the appearance face (22a) has:
- a shiny portion (23) having a shiny appearance, and
- a medium-shiny portion (25) having a medium-shiny appearance. Molded electronic device according to claim 1 in which the appearance face (22a) has:
- a shiny portion (23) having a shiny appearance, and
- a matte portion (27) having a matte appearance. Molded electronic device according to claim 1 in which the appearance face (22a) has:
- a shiny portion (23) having a shiny appearance,
- a medium shiny portion (25) having a medium shiny appearance, and
- a matte portion (27) having a matte appearance. Molded electronic device according to any one of claims 2 to 4 in which:
- the appearance face (22a) extends between a first end (21) and a second end (29), and
- the brightness of the appearance face (22a) decreases according to at least 3 levels (23, 25, 27) from the first end (21) towards the second end (29). Molded electronic device according to the preceding claim in which the brightness of the appearance face (22a) decreases strictly from the first end (21) towards the second end (29). A molded electronic device according to any one of the preceding claims wherein the support layer comprises an opaque layer (42). Molded electronic device according to any one of the preceding claims in which the molded electronic device (1) comprises a transparent layer (32) extending on the internal face (12b) and coming into contact with the electronic element (2). Molded electronic device according to any one of the preceding claims wherein the electronic element (2) is a diode, an LCD screen, an OLED screen, a micro-LED matrix, a microcontroller, a capacitor, an LED driving module , a multiplexer or an amplifier. Method for producing a molded electronic device (1) comprising the operations of:
a) providing a printed film (10) and an electronic element (2), the printed film (10) comprising a film (12) and at least one printed layer (14, 16), the film (12) having an external face (12a) and an internal face (12b), the external face (12a) having an arithmetic roughness greater than 200nm, the at least one printed layer (14, 16) comprising at least one electrically conductive layer (16 ) arranged on the internal face (12b), the electronic element (2) being electrically connected to the electrically conductive layer (16), then
b) production by injection of a support layer (32, 42) on the internal face (12b), the support layer (32, 42) being configured to stiffen the printed film (10), then
c) injection and crosslinking of polyurethane (20) to form an external protective layer (22) on the external face (12b) of the film (12), the external protective layer (22) being transparent and having an appearance face (22a ) and a contact face (22b), the contact face (22b) facing the external face (12b) of the film (12), the appearance face (22a) being opposite the contact face (22b ) and presenting a shiny appearance.