Assembly of a light source, motor vehicle lighting device comprising the assembly and method for manufacturing such an assembly

Abstract

The invention relates to an assembly (1) of a light source comprising an integrated circuit (2) with connection pads (23), a light emitting part with micro-LEDs (3) and an active surface (4), a fan-out package (5) surrounding at least a part of the integrated circuit (2), a first multi-layer metal layer (6), a second metal layer (8) comprising contact portions (81) in direct contact with a backside (22) of the integrated circuit (2), a heat spreader (11), a substrate fixation layer (9) arranged between the second metal layer (8) and the heat spreader (11), and a printed circuit board (12). The first metal layer (6) is arranged so as to cover at least a part of a frontside (21) of the integrated circuit (2) to provide an electrical connection between the pads (23) of the integrated circuit (2) and pads (7) of the assembly (1).

Description

Technical Field

[0001] This invention relates to the field of manufacturing lighting equipment for motor vehicles and related methods. Background Technology

[0002] High-end vehicle manufacturers are increasingly using arrays of light-emitting diodes (LEDs) for vehicle lighting functions. These arrangements are achieved through complex processes, either by arranging optical modules that house multiple LEDs as individual devices mounted on a heatsink, or by arranging them as arrays of single LED devices. Each individual LED is powered by a dedicated driver that includes an interface with a microcontroller that manages the beam dynamics via software. This approach can be used for dozens of beams, but with increasing resolution requirements, and constraints on vehicle cost, production, and design flexibility, this arrangement cannot be applied to high-pixel light sources (e.g., light sources comprising thousands of light sources).

[0003] Therefore, LED equipment for motor vehicles is more conservative than other lighting applications.

[0004] US2011 / 127912A1 illustrates the importance of heat dissipation in the production of LED arrays for motor vehicles. However, this approach has limitations on the number of LEDs that can be included in a single lighting device.

[0005] We are seeking a solution to this problem. Summary of the Invention

[0006] The light source assembly, motor vehicle lighting device, and method for producing the light source assembly of the present invention provide a solution to this problem. Preferred embodiments of the invention are defined in the dependent claims.

[0007] Unless otherwise specified, all terms used in this document (including technical and scientific terms) shall be interpreted in accordance with industry standard practices. It should also be understood that, unless explicitly defined herein, commonly used terms are interpreted in their conventional or overly formal sense in the relevant field.

[0008] In this document, the term “comprising” and its derivatives (such as “having”, etc.) should not be understood in an exclusive sense, that is, these terms should not be interpreted as excluding the possibility that the described and defined may include other elements, steps, etc.

[0009] In a first aspect, the present invention provides an assembly for a light source of a motor vehicle lighting device, the assembly comprising:

[0010] - An integrated circuit having a first side and a second side opposite to the first side, and further including pads located on the first side;

[0011] - The light-emitting portion includes a plurality of miniature semiconductor light sources electrically connected to a first side of an integrated circuit and an active surface arranged to modify the wavelength of the miniature semiconductor light sources;

[0012] - A fan-out package that surrounds at least a portion of an integrated circuit;

[0013] - A first multilayer metal layer, the first multilayer metal layer being arranged to cover at least a portion of a first side of the integrated circuit to provide electrical connections between pads of the integrated circuit and pads of components;

[0014] - A second metal layer, the second metal layer including a contact portion that directly contacts the second surface of the integrated circuit;

[0015] - Heat sink components;

[0016] - An array bonding layer, wherein the array bonding layer is arranged between the metal layer and the heat sink element; and

[0017] - Printed circuit board.

[0018] The components of this light source solve the heat problem caused by the presence of a large number of miniature LEDs.

[0019] Furthermore, the presence of metal layers on each side of the integrated circuit is also used to control deformation. As a result, the manufacturing process is improved.

[0020] The term "semiconductor" refers to light emitted by solid-state electroluminescence, which uses semiconductors to convert electricity into light. Compared to incandescent bulbs, solid-state lighting produces visible light with lower heat production and less energy dissipation. The generally lower weight of solid-state electronic lighting devices gives them greater shock and vibration resistance than brittle glass tubes / bulbs and long, thin filaments. They are also unaffected by filament evaporation, which can increase the lifespan of the lighting device. Some examples of these types of lighting include solid-state light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs) as the light source instead of an electric filament, plasma, or gas.

[0021] A “heat sink element” can be a heat sink, a substrate, a heat dissipation pipe or other suitable heat dissipation device.

[0022] Specifically, the second metal layer comprises copper and a finished surface made of nickel, palladium, and gold.

[0023] In motor vehicle environments, bare copper connections cannot be exposed to the environment, which is why this type of finished surface is used.

[0024] In some models, the active surface is arranged in a plane parallel to the first and second sides of the integrated circuit.

[0025] The coplanarity of the pads (anode and cathode) on the first side of the integrated circuit is controlled to ensure that thousands of connections are precisely formed.

[0026] In some specific embodiments, the second metal layer is parallel to the active surface.

[0027] These conditions are favorable for the production process.

[0028] In some specific embodiments, the distance between the component's pads and the active surface is between 2 mm and 4 mm.

[0029] This smaller distance helps simplify the masking system, which is placed above to avoid any direct incident light, for example, due to light reflection from the line or strip.

[0030] In some specific embodiments, the second side of the integrated circuit is partially covered by a fan-out package, and the second metal layer includes metal protrusions that pass through the fan-out package to contact the second side of the integrated circuit.

[0031] This arrangement provides good thermal resistance while simultaneously offering back-side protection to the integrated circuit. It also facilitates good adhesion of the second metal layer to the array bonding layer. In these cases, bonding layers such as those sputtered with metal are commonly used.

[0032] In some specific embodiments, the first metal multilayer includes at least one redistribution layer.

[0033] Currently, power supply connections are typically capable of transmitting 5 to 10 A, corresponding to a redistribution layer made of copper 5 to 10 µm thick. The plane of the redistribution layer is designed according to the principle of shortest distance to minimize the number of vias. Vias typically have a diameter of approximately 80 µm to enable the transmission of 5 to 10 A.

[0034] In some specific embodiments, the redistribution layer is arranged around the light-emitting portion.

[0035] This provides mechanical protection and helps dissipate heat.

[0036] In some specific embodiments, the first metal multilayer also includes a ribbon cable connecting the component's pads to the printed circuit board.

[0037] In other cases, alternative connections such as aluminum wire, copper wire, or gold wire, or copper clips, are used, and these can be mixed to handle power and signal connections. However, if ribbon cables are used, the wires do not need to be protected with additional resin.

[0038] In some specific cases, the first metal multilayer includes an integrated circuit that passes through a fan-out package that connects the pads of the integrated circuit to the pads of the component.

[0039] Such conductive connections are typically achieved by adding four layers of printed circuit boards or ceramic spacers, or by directly piercing polymer vias, to form an electrical connection between the driver connection area and the terminals of the component, in which case the conductive connection is located on the second surface of the device.

[0040] In some specific cases, the array bonding layer comprises at least one selected from silicone adhesives, solder alloys, silver sintering paste, or metal fillers.

[0041] When this component is used in conjunction with an auxiliary mounting configuration, the primary function of the array bonding layer is to transfer heat with the lowest possible thermal resistance to provide a mechanical bond and ensure reliability. Since there is no electrical function, either a silicone adhesive or a solder alloy with metal filler can be selected.

[0042] When this component is used with an SMD configuration, solder alloy or silver sintering paste should be used because, in this case, the layer also performs the function of providing electrical connections.

[0043] In some specific cases, the active layer is a phosphor coating that includes silicone-based materials and metal particles.

[0044] Since the active layer is a critical area for the spread of sunburn, a surface thermal conductivity higher than 50 W / m / ℃ is highly advantageous. This phosphor coating allows for the use of a redistribution layer and finished surface made of copper.

[0045] In a second aspect of the invention, the present invention provides a motor vehicle lighting device comprising a component of a plurality of light sources according to a first aspect of the invention.

[0046] In a third aspect of the invention, the present invention provides a method for manufacturing an assembly of a light source according to a first aspect of the invention, the method comprising the following steps:

[0047] - Provides the initial integrated circuit carrier;

[0048] - Select the portion of the initial integrated circuit carrier suitable for producing components of the light source;

[0049] - Place adhesive tape on the appropriate portion to form a reconstructed carrier;

[0050] - Place an intermediary layer for electrical connections;

[0051] - The portion of the encapsulated and reconstructed carrier;

[0052] - Grind and reconstruct the back side of the carrier to define the thickness or expose the back side of the silicon;

[0053] - Add a second metal layer to the second surface;

[0054] - Add a first multilayer metal layer to the first side of the reconstructed carrier to establish connections between each integrated circuit pad and each component pad;

[0055] - Attach multiple miniature semiconductor light sources;

[0056] - Cut multiple layers.

[0057] The use of a reconfigurable carrier allows for the application of a method where 100% carrier availability is known, enabling the entire carrier to be loaded with an LED array. This allows for increased yield and better control over deformation. Furthermore, the six sides of the integrated circuit are protected from environmental conditions because the package and the first and second metal layers provide protection and control over deformation.

[0058] The redistribution layer is installed early in the process, independent of the final connection of the components, as a sub-component or SMD, making the process easier and cheaper, thus increasing yield, and improving the final assembly of the heat sink components.

[0059] In some specific embodiments, after the step of attaching the miniature semiconductor light source, the method further includes at least one of the following steps:

[0060] - The reflow process after attaching a miniature semiconductor light source;

[0061] - Bottom filling deposition between the micro semiconductor light source and the reconstruction carrier;

[0062] - Performing processes such as surface treatment or thinning on the miniature semiconductor light source; and / or

[0063] - Perform photoelectric testing.

[0064] These optional additional steps enable the provision of components optimized for motor vehicle lighting equipment. Attached Figure Description

[0065] To supplement the description and allow for a better understanding of the invention, a set of drawings is provided. These drawings form part of the illustration and illustrate one embodiment of the invention. The drawings should not be construed as limiting the scope of the invention, but only as examples of how the invention can be practiced. The drawings include the following figures:

[0066] Figure 1 A general method of a first embodiment of a light source component according to the present invention is shown.

[0067] Figure 2 A general method of a first embodiment of a light source component according to the present invention is shown.

[0068] Figure 3 Details of a redistribution layer according to an embodiment of a light source component based on the present invention are shown.

[0069] Figure 4 Details of the contact protrusions between the two layers of the light source assembly according to the present invention are shown.

[0070] Figures 5a to 5c The steps of the production method according to the present invention are shown. Detailed Implementation

[0071] Where applicable, elements of the exemplary embodiments are systematically represented by the same reference numerals throughout the drawings and detailed description:

[0072] 1. Components of the light source

[0073] 2 Integrated Circuits

[0074] 21 The first side of an integrated circuit

[0075] 22 The second side of the integrated circuit

[0076] 23. Pads for integrated circuits

[0077] 24 Anode

[0078] 25 Cathode

[0079] 3. Miniature LEDs

[0080] 31 Miniature LED pads

[0081] 4. Active surfaces

[0082] 5 Fan-out type package

[0083] 6 First multilayer metal layer

[0084] 61. Redistribution Layer

[0085] 62 ribbon cable

[0086] 63 Polymer through-hole

[0087] 64 Passivation layer

[0088] 7 Connecting pads

[0089] 71 First Polymer

[0090] 72 Second Polymer

[0091] 73 Third Polymer

[0092] 8 Second metal layer

[0093] 81 Contact portion of the second metal layer

[0094] 9. Binding Layer

[0095] 10. Motor vehicle lighting equipment

[0096] 11 Radiator

[0097] 12 Printed Circuit Boards

[0098] 13. Intermediate thermal layer

[0099] 101 Initial Carrier

[0100] 102 Appropriate Part

[0101] 103 Reconstruction Carrier

[0102] Exemplary embodiments have been described in sufficient detail to allow those skilled in the art to perform and implement the systems and processes described herein. It is important to understand that these examples may be provided in many different forms and should not be construed as being limited to the examples presented herein.

[0103] Therefore, although embodiments may be modified in various ways and take various alternative forms, specific embodiments thereof are shown in the accompanying drawings and described in detail below by way of example. This is not intended to limit the particular forms disclosed. Rather, all modifications, equivalents, and alternatives falling within the scope of the appended claims will be included. Where applicable, elements of exemplary embodiments are systematically indicated by the same reference numerals throughout the drawings and detailed description.

[0104] Figure 1 and 2 The general method of two embodiments of the light source component 1 according to the present invention is shown. Figure 1 The connection to the base is oriented, and Figure 2 This illustrates a connection made for use with a solder mask (SMT) defined as a joint.

[0105] exist Figure 1 and Figure 2 The component 1 shown in the figure includes an integrated circuit 2, a light-emitting portion with micro LEDs 3 and active surfaces 4, a fan-out package 5, a first metal multilayer 6, a second metal layer 8, a chip bonding layer 9, a heat sink 11, and a printed circuit board 12.

[0106] The integrated circuit 2 is an ASIC with a first side 21 and a second side 22 opposite to the first side 21 and includes a pad 23 located on the first side 21.

[0107] The light-emitting portion includes a plurality of micro-LEDs 3 electrically connected to the first side 21 of the integrated circuit 2 for receiving power and control. The active surface 4 is arranged to modify the wavelength of the micro-LEDs 3 so that the final light emission is white, as required by motor vehicle functions.

[0108] The fan-out package 5 is arranged to surround the integrated circuit 2. The fan-out component 5 is responsible for laterally surrounding the integrated circuit 2, but a small portion of the second side 22 of the integrated circuit 2 is also protected by the fan-out component 5.

[0109] A first metal multilayer 6 is arranged to cover a portion of the first surface 21 of the integrated circuit 2. Since this first metal multilayer 6 differs in each variant, it will be described in detail later. In all cases, this first metal multilayer 6 provides electrical connections between the pads 23 of the integrated circuit 2 and the pads 7 of the component.

[0110] The second metal layer 8 includes metal protrusions 81 that extend through the fan-out package 5 to directly contact the second side 22 of the integrated circuit 2. This second metal layer is made of copper and has a nickel-plated surface.

[0111] The array bonding layer 9 is arranged between the second metal layer 8 and the heat sink 11, and its purpose is different for each embodiment.

[0112] As can be seen from these two figures, the active surface 4 is arranged along a plane parallel to the first side 21 and the second side 22 of the integrated circuit 2. This plane is also parallel to the second metal layer 8. This parallel arrangement makes it easier to design and manufacture, and also provides good structural robustness, allowing these small pads to maintain their shape despite being subjected to thermal and structural loads.

[0113] Above the micro-LED 3, the active layer 4 comprises a phosphor coating deposited by sputtering. This coating is a silicone-based material filled with metal particles to impart white light to the ultimately projected light (since LEDs emit light at blue wavelengths). In some embodiments, this coating may also be spread on the redistribution layer for additional protection and stress relief. However, this layer does not reach the pads of component 7, as it would be considered a contaminant for these components. The additional area provided by the fan-out package 5 helps to avoid this contamination.

[0114] Figure 1 An embodiment of a light source component 1 is shown, which is specifically configured for base connection. Therefore, the structure of the first metal multilayer is... Figure 2 Their structures are different.

[0115] In this figure, the first metal multilayer includes a plurality of redistribution layers 61 that provide electrical connections between the pads 23 of the driver 2 and the pads 7 of the component, in this embodiment, the pads 7 being located on top of the component 1.

[0116] The minimum distance between pad 7 and active surface 4 depends on the optical system selected and placed above the light source component, but can vary between 2 mm and 4 mm. This smaller distance helps simplify the masking system placed above, so as to avoid any direct incident light such as light reflection from the ribbon cable or band 62.

[0117] The thermal problem at the location of the redistribution layer 61 (around the light-emitting portion) is also mitigated.

[0118] In this embodiment, the bonding layer 9 is used to transfer heat with the lowest possible thermal resistance. A solder paste with metallic filler is used, allowing heat to be easily dissipated toward the heat sink 11. Furthermore, the chip bonding layer 9 mechanically bonds the light source component 1 to the main structure of the lighting device represented by the heat sink 11.

[0119] Figure 2 Another embodiment of component 1 of the light source is shown, which is specifically configured for use in a connection defined by a solder mask (SMT). Therefore, the structure of the first metal multilayer is... Figure 1 Their structures are different.

[0120] In this configuration, the first metal multilayer 6 includes a conductive via 63 that passes through the fan-out package 5 to connect the pads of the driver 23 to the pads of the component 7, wherein the component 7 is located below the component 1.

[0121] In this configuration, the bonding pads 7 are connected to the printed circuit board 12 via a bonding layer 13. Since this bonding layer 13 performs an electrical function, a solder alloy is used. In various embodiments, electrically conductive adhesives, with or without sintering, can be used for this purpose.

[0122] Figure 3 Details of a redistribution layer according to an embodiment of a light source component based on the present invention are shown.

[0123] Integrated circuit 2 includes a passivation layer 64 deposited on a first surface 21 of the integrated circuit. The passivation layer is not applied to the pads of driver 23, which receives a first redistribution layer 61. This first redistribution layer 61 is deposited on a first polymer layer 71, while a second polymer layer 72 is deposited on top, leaving space for connections to the second redistribution layer 61'. A third polymer layer 73 is deposited on the second redistribution layer 61', leaving blank space for the third and final redistribution layers. This third redistribution layer provides connection pads 7 for components, which are used to connect to the printed circuit board 12 via ribbon cables 62, such as... Figure 1 As shown.

[0124] The micro LED 3 is connected to the anode 24 and cathode 25 of the driver by solder paste 13, which connects each anode and each cathode to the connection pad of the LED 31.

[0125] Figure 4 Details of the contact protrusions between the two layers of the light source assembly according to the present invention are shown.

[0126] In this embodiment, the package portion 5 includes a portion covering the second side 22 of the integrated circuit 2, and the second metal layer 8 includes metal protrusions 81 that pass through this portion of the package 5 to facilitate direct contact with the second side 22 of the integrated circuit 2. The second metal layer 8 is made of copper and has a nickel-plated side.

[0127] Figures 5a to 5c The steps of the production method according to the present invention are shown.

[0128] Figure 5a The setup of the initial carrier 101 is shown, in which the integrated circuits for future components are designed.

[0129] The raw wafer was tested to identify the appropriate sections. Next, the raw wafer was cut and, according to… Figure 5b Appropriate portions 102 are arranged on the tape to form a reconstructed wafer 103.

[0130] Various components are added to the reconfigured carrier 103 to form a complete electronic assembly. First, an interlayer is added to provide electrical connection between the well-conditioned portion and the future substrate to which the assembly will be connected.

[0131] Next, the surface of the reconstructed carrier is packaged to secure each portion of the carrier and process the reconstructed carrier as a single piece. Then, the reconstructed carrier is ground to expose the silicon in the benign portions, allowing metal layers to be added. These metal layers control deformation and provide electrical connections between the terminals of the integrated circuit and the terminals of the component. Once these layers are added, the reconstructed carrier is ready to receive LED clusters.

[0132] The redistribution layer is installed early in the process, independent of the final connection of the components, as a sub-component or SMD, making the process easier and cheaper, thus improving yield, and also improving the final assembly of the heat sink components.

[0133] Figure 5c The final result of the reconstructed carrier 103 after the aforementioned steps is shown. All necessary electronic components are arranged to facilitate the formation of an assembly of the light source according to the invention.

[0134] Once the LEDs are arranged in the reconfiguration carrier, a reflow process occurs, followed by underfill deposition between the microLEDs and the conductive portions. The microLED array is then processed and prepared for testing and isolation.

Claims

1. An assembly (1) for a light source in a motor vehicle lighting device (10), the assembly comprising: - Integrated circuit (2), the integrated circuit (2) having a first side (21) and a second side (22) opposite to the first side (21), and further including a connection pad (23) located on the first side (21); - The light-emitting portion includes a plurality of miniature semiconductor light sources (3) electrically connected to the first side (21) of the integrated circuit (2) and an active surface (4) arranged to modify the wavelength of the miniature semiconductor light sources (3). - A fan-out package (5) that surrounds at least a portion of the integrated circuit (2); - A first multilayer metal layer (6) is arranged to cover at least a portion of the first side (21) of the integrated circuit (2) to provide an electrical connection between the connection pad (23) of the integrated circuit (2) and the connection pad (7) of the component; - Second metal layer (8), the second metal layer (8) includes a contact portion (81) that is in direct contact with the second side (22) of the integrated circuit (2); - Heat sink component (11); - An array bonding layer (9) is disposed between the second metal layer (8) and the heat sink element (11); and - Printed circuit board (12).

2. The light source assembly (1) according to claim 1, wherein, The second metal layer (8) comprises copper and has a finished surface made of nickel, palladium and gold.

3. The component (1) of the light source according to claim 1 or 2, wherein, The active surface (4) is arranged in a plane parallel to the first side (21) and the second side (22) of the integrated circuit (2).

4. The light source assembly (1) according to claim 3, wherein, The second metal layer (8) is parallel to the active surface (4).

5. The component (1) of the light source according to claim 1 or 2, wherein, The distance between the pads of the component (7) and the active surface (4) is between 2 mm and 4 mm.

6. The component (1) of the light source according to claim 1 or 2, wherein, The second side (22) of the integrated circuit (2) is partially covered by the fan-out package (5), and the second metal layer (8) includes metal protrusions (81) that pass through the fan-out package (5) to contact the second side (22) of the integrated circuit (2).

7. The component (1) of the light source according to claim 1 or 2, wherein, The first multilayer metal layer (6) includes at least one redistribution layer (61).

8. The light source assembly (1) according to claim 7, wherein, The redistribution layer (61) is arranged around the light-emitting portion.

9. The light source assembly (1) according to claim 7, wherein, The first multilayer metal layer (6) also includes a ribbon cable (62) connecting the connection pads (7) of the component to the printed circuit board (12).

10. The component (1) of the light source according to claim 1 or 2, wherein, The first multilayer metal layer (6) includes a via (63) that passes through the fan-out package (5) and connects the connection pad (23) of the integrated circuit to the connection pad (7) of the component.

11. The component (1) of the light source according to claim 1 or 2, wherein, The array bonding layer (9) comprises at least one material selected from silicone adhesives or metal fillers.

12. The light source assembly (1) according to claim 11, wherein, The metal filler is a solder alloy or silver sintering paste.

13. The component (1) of the light source according to claim 1 or 2, wherein, The active surface (4) is a phosphor coating consisting of silicone-based materials and metal particles.

14. A motor vehicle lighting device (10) comprising a plurality of light sources as described in any of the preceding claims (1).

15. A method for producing an assembly (1) of a light source according to any one of claims 1 to 13, the method comprising the following steps - Provide an initial integrated circuit carrier (101); - Select a portion (102) of the initial integrated circuit carrier (101) suitable for producing components of a light source. - Place an appropriate portion of the adhesive tape to form a reconstructed carrier (103); - Place an intermediary layer for electrical connections; - Select a suitable portion (102) for encapsulation of the reconstructed carrier (103). - Grind the back side of the reconstructed carrier (103) to define the thickness or expose the back side of the silicon; - Add a second metal layer to the second surface of the reconstructed carrier; - Add a first multilayer metal layer to the first side of the reconstructed carrier to establish a connection between each integrated circuit pad and each component pad; - Attach multiple miniature semiconductor light sources; - Cut and reconstruct the carrier.

16. The method according to claim 15, wherein, Following the step of attaching the miniature semiconductor light source, the method further includes at least one of the following steps: - The reflow process after attaching the miniature semiconductor light source; - Fill the bottom between the micro semiconductor light source and the reconstruction carrier with deposition; - Perform processing on a miniature semiconductor light source; and / or - Perform photoelectric testing.

17. The method according to claim 16, wherein, The treatment is a surface treatment or a thinning treatment.

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