Ceramic and build-up carriers for light emitting diode (LED) arrays

Abstract

A circuit board, an LED lighting system, and a manufacturing method are described. The circuit board includes a ceramic carrier and a body on the ceramic carrier. The body includes multiple dielectric layers and multiple slots formed through the entire thickness of the multiple dielectric layers. The slots are filled with a dielectric material. A conductive pad is provided on the surface of each of the slots opposite the ceramic carrier.

Description

[Technical field]

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 958,058, filed January 7, 2020, U.S. Patent Application No. 16 / 809,104, filed March 4, 2020, and European Patent Application No. 20166601.3, filed March 30, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] Precision controlled lighting applications can require the production and manufacturing of miniature addressable light emitting diode (LED) lighting systems. The smaller size of such systems can require non-traditional components and manufacturing processes. Summary of the Invention

[0003] A circuit board, an LED lighting system, and a method of manufacture are described. The circuit board includes a ceramic carrier and a body on the ceramic carrier. The body includes a plurality of dielectric layers and a plurality of vias formed through the entire thickness of the plurality of dielectric layers. The vias include: metal A conductive pad is provided on the surface of each of these vias opposite the ceramic carrier. [Brief description of the drawings]

[0004] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which: [Figure 1] FIG. 2 is a top view of an example of an LED array. [Diagram 2] FIG. 2 is a cross-sectional view of an example of a circuit board. [Diagram 3] FIG. 3 is a cross-sectional view of an example of an LED lighting system incorporating the circuit board of FIG. 2. [Figure 4] FIG. 4 is a diagram of an example vehicle headlamp system incorporating the LED lighting system of FIG. 3. [Diagram 5]FIG. 2 is a diagram of another example of a vehicle headlamp system. [Figure 6] FIG. 1 is a block diagram of an example of a wireless device. [Figure 7] FIG. 13 is a rear view of another example of a wireless device. [Figure 8] 4 is a flow diagram of an example of a method for manufacturing an LED lighting system, such as the LED lighting system of FIG. 3. [Figure 9A] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9B] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9C] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9D] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9E] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9F] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9G] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9H] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9I] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9J] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9K] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9L] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9M] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9N] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9O] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9P] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. [Figure 9Q] 9A-9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Examples of several different light illumination system and / or light emitting diode ("LED") implementations are described more fully below with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example may be combined with features found in one or more other examples to achieve further implementations. Accordingly, it is to be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only, and that they are not intended to limit the present disclosure in any way. Like elements are referenced with like numerals throughout.

[0006] It is understood that terms such as first, second, third, etc. may be used herein to describe various elements, but the elements should not be limited by these terms. These terms may be used to distinguish one element from another element. For example, a first element may be referred to as a second element and a second element may be referred to as a first element without departing from the scope of the present invention. As used herein, the term "and / or" may include any and all combinations of one or more of the associated listed items.

[0007] It is understood that when an element, e.g., a layer, region, or substrate, is referred to as being "on" or extending "upon" another element, it may be directly on or extending directly onto the other element, or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly onto" another element, there may be no intervening elements present. It is also understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element and / or may be connected or coupled to the other element via one or more intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements between the element and the other element. It is understood that these terms are intended to encompass elements in different orientations in addition to the orientation depicted in the figures.

[0008] Relative terms such as "lower," "above," "upper," "lower," "horizontal," or "vertical" may be used herein to describe the relationship of one element, layer, or region to another element, layer, or region as depicted in the figures. It is understood that these terms are intended to encompass devices in different orientations in addition to the orientation depicted in the figures.

[0009] Whether the LEDs, LED arrays, electrical components, and / or electronic components are contained on one, two, or more electronics boards may also depend on design constraints and / or applications.

[0010] Among the most efficient light sources currently available are semiconductor light emitting devices (LEDs), or light output emitting devices, such as devices that emit ultraviolet (UV) or infrared (IR) light output. These devices (hereinafter, "LEDs") may include light emitting diodes, resonator type light emitting diodes, vertical cavity laser diodes, edge emitting lasers, or the like. LEDs may be attractive candidates for many different applications, for example, due to their small size and lower power requirements. For example, they may be used as light sources (e.g., flashlights and camera flashes) for handheld battery-powered devices such as cameras and mobile phones. They may also be used, for example, for automotive lighting, head-up display (HUD) lighting, horticultural lighting, street lighting, torches for video, general lighting (e.g., home, store, office and studio lighting, theater / stage lighting, and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, used as backlights for displays, and for IR spectroscopy. A single LED will provide less light than an incandescent light source, therefore, in applications where more brightness is desired or required, a multi-junction device or an array of LEDs (e.g., monolithic LED arrays, micro LED arrays, etc.) may be used.

[0011] Figure 1 is a top view of an example LED array 102. In the example shown in Figure 1, the LED array 102 is an array of emitters 120. LED arrays may be used in applications, such as those that require precise control of the LED array emitters. The emitters 120 in the LED array 102 may be individually addressable or addressable in groups / subsets.

[0012] A close-up of a 3×3 portion of the LED array 102 is also shown in FIG. 1. As shown in the close-up of the 3×3 portion, the LED array 102 may include a plurality of emitters 120, each having a width w1. In an embodiment, the width w1 may be about 100 μm or less (e.g., 30 μm). The lanes 122 between the emitters 120 may be as wide as a width w2. In an embodiment, the width w2 may be about 20 μm or less (e.g., 5 μm). The lanes 122 may provide an air gap between adjacent emitters or may include other materials. The distance D1 from the center of one emitter 120 to the center of an adjacent emitter 120 may be about 120 μm or less (e.g., 30 μm). It is understood that the widths and distances provided herein are merely examples and the actual widths and / or dimensions may vary.

[0013] It is understood that although Fig. 1 illustrates square emitters arranged in a symmetric matrix, emitters of any shape and arrangement may be used with the embodiments described herein. For example, the LED array 102 of Fig. 1 may include over 20,000 emitters in any applicable arrangement, such as a 200 x 100 matrix, a symmetric matrix, an asymmetric matrix, or the like. It is also understood that multiple sets of emitters, matrices, and / or substrates may be arranged in any applicable configuration to implement the embodiments described herein.

[0014] As mentioned above, an LED array, such as LED array 102, may include multiple emitters with fine pitch and line spacing. LED arrays, such as this, may be referred to as micro LED arrays or simply micro LEDs. Micro LEDs may include an array of individual emitters provided on a substrate, or may be a single silicon wafer or die that is divided into segments that form the emitters. The latter type of micro LEDs may be referred to as monolithic LEDs. Such LED arrays may also require significant power, such as 60 watts or more, to power them, and therefore may generate significant heat during operation. Thus, such arrays require circuit boards that can fit into the fine line spacing and provide sufficient heat dissipation.

[0015] The embodiments described herein provide circuit boards, LED lighting systems incorporating the circuit boards, and methods of manufacture that can support LED arrays with fine line spacing and provide sufficient heat dissipation to meet the thermal requirements of such LED arrays. Such LED arrays and LED lighting systems can be used in a variety of applications, including, for example, camera flash and vehicle lighting system applications.

[0016] FIG. 2 is a cross-sectional view of a circuit board 200. In the example shown in FIG. 2, the circuit board 200 includes a ceramic carrier 202. The ceramic carrier 202 may have a top surface 218 and a bottom surface 214. A body 212 is disposed on the top surface 218 of the ceramic carrier 202. The body 212 has a top surface 220 and a bottom surface 216, with the bottom surface 216 resting on the top surface 218 of the ceramic carrier 202. The body 212 may be formed from a plurality of layers 204 of dielectric material. A number of vias 206 are formed through the layers 204 of dielectric material. In an embodiment, the vias are formed through the entire thickness (t1) of the layers 204 of dielectric material. The vias 206 may be filled and / or plated with a metal material. When the vias are formed completely through the entire thickness of the layers 204 of dielectric material, the metal in the vias 206 contacts the ceramic carrier 202. A metal pad 208 may be disposed on a surface of each of the vias 206 opposite the ceramic carrier 202.

[0017] The vias 206 may be arranged in pairs to allow contact with multiple LED devices or emitters, each of which may include a pair of metal contacts. In an embodiment, the vias 206 may be microvias or slots and may have a width w3 and the space between adjacent pairs of vias may have a width w4. In an embodiment, w3 may be in the range of 50 μm to 200 μm and w4 may be in the range of 20 μm to 200 μm. The small width of the vias 206 and the small spacing between pairs of vias 206 may allow the circuit board 200 to be used with LED arrays, such as the LED array 102 of FIG. 1, having fine line spacing.

[0018] The vias 206 may be filled and / or plated with a metal material having good thermal conductivity. In an embodiment, the metal material may be a copper, silver, or nickel material. The ceramic carrier 202 may be formed from a material having high thermal conductivity and high electrical resistivity. In an embodiment, the ceramic carrier 202 may be formed from aluminum nitride (AlN), zirconia (ZrO2), or aluminum oxide (Al2O3). Using such materials for the ceramic carrier 202 allows the vias 206 to be used both to make electrical connections to the conductive pads 208 and to dissipate heat from an LED array or other semiconductor device mounted on the conductive pads 208. In other words, when the vias 206 are formed through the entire thickness of the layer 204 of dielectric material, the vias 206 may dissipate heat from an LED array or other semiconductor device mounted on the metal pads 208 to the ceramic carrier 202, whose high thermal conductivity allows the heat to be dissipated quickly into the environment. Furthermore, since the ceramic carrier 202 has good electrical resistivity, it may prevent the vias 206 from shorting to each other.

[0019] As mentioned above, the body 212 may have a thickness t1. In an embodiment, the thickness t1 may be in the range of 20 μm to 50 μm. Thus, the thickness t1 may be kept relatively thin to minimize the insulation provided by the circuit board.

[0020] Figure 3 is a cross-sectional view of an LED lighting system 300 including the circuit board 200 of Figure 2 with an array of light emitting diode (LED) devices 304 mounted thereon. Although the example shown in Figure 3 includes an array of individual LED devices 304, the embodiments described herein are applicable to any type of LED array, such as the LED array 102 of Figure 1, which may be an array of individual emitters or a monolithic LED array that includes a single silicon wafer or die divided into segments that form emitters. If a monolithic LED array is used, each of the emitters in the array may have a pair of metal contacts that may be electrically coupled (e.g., via solder) to a corresponding pair of metal pads on the circuit board.

[0021] In the example shown in FIG. 3, the LED devices 304 each include a semiconductor structure 308, a wavelength conversion layer 306 on the semiconductor structure 308, and two metal contacts 310a and 310b. The semiconductor structure can be any type of semiconductor structure that emits light when excited and can include one or more p-type regions, n-type regions, and an active light emitting region. In an embodiment, the two contacts 310a and 310b can be p-type and n-type electrodes, respectively. The wavelength conversion layer 306 can be separate from, proximate to, or directly on the semiconductor structure 308. An active layer in the semiconductor structure 308 emits light into the wavelength conversion layer 306 when turned on, and the wavelength conversion layer 306 further acts to change the wavelength of the light emitted by the active layer. Wavelength-converting layer 306 may include any luminescent material, such as phosphor particles or ceramic phosphor elements in a transparent or translucent binder or matrix, that absorbs light of one wavelength and emits light of a different wavelength.

[0022] 3, each pair of contacts 310a and 310b of each of the LED devices 304 are electrically coupled (e.g., via solder) to a corresponding pair of metal pads 208 on the circuit board 200. A solder mask layer 302 is provided on the top surface 220 of the circuit board 200 in areas not occupied by the metal pads 208. In embodiments, the solder mask layer 302 can be any layer or type of material that protects the circuit board and / or reflects light.

[0023] As mentioned above, LED lighting systems such as that shown in Figure 3 can be used in many different applications and can be particularly useful in vehicle headlamp systems and flash applications where closely packed LED arrays and / or individually addressable LED devices or emitters may be desired. Figures 4, 5, 6, and 7 are diagrams of example application systems that may incorporate an LED lighting system such as LED lighting system 300 of Figure 3.

[0024] Figure 4 is a diagram of an example vehicle headlamp system 400 that may incorporate an LED lighting system such as, for example, LED lighting system 300 of Figure 3. The example vehicle headlamp system 400 shown in Figure 4 includes a power line 402, a data bus 404, an input filter and protection module 406, a bus transceiver 408, a sensor module 410, an LED direct current to direct current (DC / DC) module 412, a logic low dropout (LDO) module 414, a microcontroller 416, and an active headlamp 418. In an embodiment, the active headlamp 418 may include an LED lighting system such as, for example, LED lighting system 300 of Figure 3.

[0025] The power line 402 can have an input for receiving power from the vehicle, and the data bus 404 can have inputs / outputs through which data can be exchanged between the vehicle and the vehicle headlamp system 400. For example, the vehicle headlamp system 400 can receive commands from elsewhere in the vehicle, such as commands to turn on turn signals or turn on headlamps, and can transmit feedback to elsewhere in the vehicle if desired. The sensor module 410 can be communicatively coupled to the data bus 404 and can provide additional data to the vehicle headlamp system 400 or elsewhere in the vehicle, such as related to environmental conditions (e.g., time of day, rain, fog, or ambient light levels), vehicle status (e.g., parked, moving, speed, or direction of movement), and the presence / location of other objects (e.g., vehicles or pedestrians). A headlamp controller separate from the vehicle controller communicatively coupled to the vehicle data bus can also be included in the vehicle headlamp system 400. In FIG. 4, the headlamp controller can be a microcontroller, such as a microcontroller (μc) 416. The microcontroller 416 may be communicatively coupled to the data bus 404 .

[0026] The input filter and protection module 406 can be electrically coupled to the power lines 402 and can support various filters to, for example, reduce conducted emissions and provide power immunity. Additionally, the input filter and protection module 406 can provide electrostatic discharge (ESD) protection, load dump protection, alternator field decay protection, and / or reverse polarity protection.

[0027] An LED DC / DC module 412 may be coupled between the filter and protection module 406 and the active headlamp 418 to receive the filtered power and provide a drive current to power the LEDs in the LED array of the active headlamp 418. The LED DC / DC module 412 may have an input voltage between 7 and 18 volts, with a nominal voltage of approximately 13.2 volts, and an output voltage that may be slightly (e.g., 0.3 volts) higher than the maximum voltage for the LED array (determined, for example, by factory or field calibration and operating conditioning due to load, temperature, or other factors).

[0028] The logic LDO module 414 may be coupled to the filter and protection module 406 to receive the filtered power. The logic LDO module 414 may also be coupled to the microcontroller 416 and the active headlamp 418 to provide power to a silicon backplane (e.g., CMOS logic) within the microcontroller 416 and / or the active headlamp 418.

[0029] The bus transceiver 408 may have, for example, a universal asynchronous receiver transmitter (UART) or a serial peripheral interface (SPI) interface and may be coupled to a microcontroller 416. The microcontroller 416 may translate vehicle inputs based on or including data from the sensor module 410. The translated vehicle inputs may include video signals that can be transferred to an image buffer in the active headlamp module 418. Additionally, the microcontroller 416 may load a default image frame at startup to check for open / short pixels. In an embodiment, the SPI interface may load the image buffer into the CMOS. The image frame may be a full frame, a difference frame, or a partial frame. Other functions of the microcontroller 416 may include a control interface monitoring of CMOS status including die temperature and logic LDO outputs. In an embodiment, the LED DC / DC outputs may be dynamically controlled to minimize headroom. In addition to providing image frame data, other headlamp functions may also be controlled, such as auxiliary use in conjunction with width or turn indicator lights, and / or operation of daytime running lights.

[0030] Figure 5 is a diagram of another example vehicle headlamp system 500. The example vehicle headlamp system 500 shown in Figure 5 includes an application platform 502, two LED lighting systems 506 and 508, and optical systems 510 and 512. The two LED lighting systems 506 and 508 may be LED lighting systems such as the LED lighting system 300 of Figure 3, or may include the LED lighting system 300 plus some or all of the other modules in the vehicle headlamp system 400 of Figure 4. In the latter embodiment, the LED lighting systems 506 and 508 may be vehicle headlamp subsystems.

[0031] The LED lighting system 508 may emit a light beam 514 (shown between arrows 514a and 514b in FIG. 5). The LED lighting system 506 may emit a light beam 516 (shown between arrows 516a and 516b in FIG. 5). In the embodiment shown in FIG. 5, a secondary optic 510 is adjacent to the LED lighting system 508, and light emitted from the LED lighting system 508 passes through the secondary optic 510. Similarly, a secondary optic 512 is adjacent to the LED lighting system 506, and light emitted from the LED lighting system 506 passes through the secondary optic 512. In an alternative embodiment, the secondary optic 510 / 512 may not be provided in the vehicle headlamp system.

[0032] When included, the secondary optics 510 / 512 may be or include one or more light guides. The one or more light guides may be edge-lit or have an internal opening that defines the inner edge of the light guide. The LED lighting systems 508 and 506 (or active headlamps of a vehicle headlamp subsystem) may be inserted into the internal openings of the one or more light guides such that they inject light into the inner edge (inner-opening light guides) or outer edge (edge-lit light guides) of the one or more light guides. In embodiments, the one or more light guides may shape the light emitted by the LED lighting systems 508 and 506 as desired, such as to have a gradient, a chamfered distribution, a narrow distribution, a wide distribution, or an angular distribution.

[0033] The application platform 502 may provide power and / or data to the LED lighting systems 506 and / or 508 via lines 504, which may include one or more or portions of the power lines 402 and data bus 404 of Figure 4. There may be one or more sensors (which may be sensors within system 400 or other additional sensors) inside or outside the housing of the application platform 502. Alternatively, or in addition, as shown in the example of LED lighting system 400 of Figure 4, each LED lighting system 508 and 506 may include its own sensor module, connectivity and control module, power module, and / or LED array.

[0034] In an embodiment, vehicle headlamp system 500 may represent an automobile with a steerable light beam, where the LEDs may be selectively operated to provide a steerable beam. For example, an array of LEDs (e.g., LED array 102) may be used to define or project a shape or pattern, or to illuminate only selected sections of a road. In an example embodiment, infrared cameras or detector pixels in LED systems 506 and 508 may be sensors (e.g., similar to the sensors in sensor module 410 of FIG. 4) that identify portions of a scene (e.g., a road or a crosswalk) that require illumination.

[0035] Figure 6 is a diagram of an example of a wireless device 600. In the example shown in Figure 6, the wireless device 600 includes a processor 612, a transceiver 602, an antenna 604, a speaker / microphone 606, a keypad 608, a display / touchpad 610, a memory 616, a power source 618, and a camera 614.

[0036] The processor 612 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a microprocessor, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, an integrated circuit (IC), a state machine, and the like. The processor 612 may be coupled to and receive user input data from the speaker / microphone 606, the keypad 608, the display / touchpad 610, and / or the camera 614. The processor 612 may also output user data to the speaker / microphone 606, the keypad 608, the display / touchpad 610, and / or the camera 614. Additionally, the processor 612 may access information from and store data in any type of suitable memory, such as, for example, the memory 616. The processor 612 may receive power from a power source 618 and may be configured to distribute and / or control power to other components within the wireless device 600.

[0037] The processor 612 may also be coupled to a camera 614. In an embodiment, the camera 614 may include, for example, an image sensor, readout circuitry, a flash module, and / or other necessary circuitry or controls necessary to operate the camera 614. In an embodiment, the flash module may include, for example, an LED lighting system, such as LED lighting system 300 of FIG. 3, and a driver, one or more sensors, and / or other circuitry or controls necessary to operate the flash.

[0038] Figure 7 is a rear view of the wireless device 700 showing further details of the camera 614. In the example shown in Figure 7, the wireless device 700 includes a housing 720 and a camera 614. The camera 614 includes a lens 740 through which an image sensor (not shown in Figure 7) of the camera may capture an image of a scene. The camera module 614 may also include a flash 750, which may include one or more LED arrays, which may be part of one or more LED lighting systems, such as, for example, the LED lighting system 300 of Figure 3.

[0039] FIG. 8 is a flow diagram of an example of a method 800 for manufacturing an LED lighting system, such as the LED lighting system 300 of FIG. 3. FIGS. 9A, 9B, 9C, 9D, 9E, 9F, 9G, 9H, 9I, 9J, 9K, 9L, 9M, 9N, 9O, 9P, and 9Q are cross-sectional views of an LED lighting system at various stages in the manufacturing method. In an embodiment, a finer geometry high density interconnect build-up process is used to stack dielectric layers on a ceramic carrier. Various dielectric materials can be used, such as organic materials, or more specifically, bismaleimide triazine (BT) resin. A ceramic carrier (e.g., AlN carrier) can be used as the backbone of the build-up process.

[0040] In the example method 800 of Figure 8, a first metal pad is formed 802 on a ceramic carrier, such as an AlN carrier, as described above. Figures 9A, 9B, 9C, 9D, 9E, 9F, and 9G provide example structures at various points in the formation of the first metal pad.

[0041] In an embodiment, the method may be used to simultaneously manufacture multiple circuit boards. For example, as shown in FIG. 9A, two ceramic carriers 902a and 902b may be attached to each other, for example, using adhesive 904, to form a structure 900A. In an embodiment, the adhesive may be a tape or a temporary adhesive. In the example shown in FIG. 9A, adhesive 904 is disposed between a first ceramic carrier 902a and a second ceramic carrier 902b. Although the examples in FIGS. 9A-9Q show the simultaneous manufacture of multiple circuit boards, one skilled in the art will recognize that a similar method may be used to manufacture a single circuit board (e.g., by not joining the two carriers and not performing processing on both carriers).

[0042] As shown in FIG. 9B, a layer of metal material 906a and 906b may be formed on the outer surfaces (e.g., surfaces not bonded together) of the first and second carriers 902a and 902b. In an embodiment, the metal layer may be formed by sputtering. For example, copper sputtering may be performed on the structure 900A to form a thin film of copper on the outer surfaces of the carriers 902a and 902b. However, one skilled in the art will appreciate that other methods and materials may be used to form the metal layer on the surfaces of the first and second carriers 902a and 902b.

[0043] As shown in Figure 9C, films 908a and 908b may be formed on metal layers 906a and 906b, respectively, to form structure 900C. In an embodiment, the films may be dry films, such as photoresist, formed using dry film lamination. However, one skilled in the art will appreciate that other methods, such as spin coating, may be used to form films 908a and 908b on the surfaces of metal layers 906a and 906b.

[0044] 9D, structure 900C may undergo an imaging or photolithography process that removes portions of films 908a and 908b to form openings in the films and form structure 900D. In an embodiment, this may be done by placing patterns 910a and 910b, such as glass patterns, on structure 900C and exposing structure 900C to light (e.g., ultraviolet (UV) light) that is projected through the pattern. This may result in the UV light hitting the portions of films 908a and 908b that are desired to be removed, or alternatively, the portions of films 908a and 908b that should not be removed.

[0045] As shown in FIG. 9E, desired portions of the films 908a and 908b can be removed, for example, by applying a developer to the structure 900D. A number of different types of developers can be used. In an embodiment, the portions of the films 908a and 908b that were exposed to light in FIG. 9D can be soluble to the developer, or the portions of the films 908a and 908b that were not exposed to light in FIG. 9D can be soluble to the developer. Exposing the structure 900D to the developer can result in the structure 900E having openings 911a and 911b formed in the films 908a and 908b. The openings 911a and 911b can form part of the vias 206 of the circuit board 200 of FIG. 2.

[0046] As shown in Figure 9F, openings 911a and 911b in membranes 908a and 908b may be filled and / or plated with a metallic material to form structure 900F. In embodiments, the openings extend entirely through membranes 908a and 908b, leaving corresponding areas of ceramic carriers 902a and 902b exposed. Openings 911a and 911b may be plated and / or otherwise filled with a metallic material (e.g., copper) to form metal-plated and / or metal-filled openings 912a and 912b.

[0047] As shown in FIG. 9G, the remaining portions of the membranes 908a and 908b and the portions of the metal layers 906a and 906b thereunder may be removed, leaving first metal pads 912a and 912b on the carriers 902a and 902b to form the structure 900G. This may be done, for example, by stripping the remaining portions of the membranes 908a and 908b and then performing a copper or other metal etch on the portions of the metal layers 906a and 906b thereunder. The resulting panel may then be ready for further build-up processes.

[0048] Referring again to Figure 8, a layer of dielectric material may be formed over the first metal pads (804). Figure 9H provides an example of a structure 900H showing a layer of dielectric material 914a and 914b formed over the first metal pads 912a and 912b. In an embodiment, the dielectric material may be laminated over the first metal pads 912a and 912b, although one skilled in the art will appreciate that other methods may be used, such as, for example, molding.

[0049] Vias may be formed (806) in the dielectric material above the first metal pads. FIG. 9I provides an example of a structure 900I showing vias 916a and 916b formed in layers of dielectric material 914a and 914b. In an embodiment, the vias 916a and 916b may be microvias or slots and may be formed using, for example, laser ablation or drilling, although one skilled in the art will appreciate that other methods may be used. The vias 916a and 916b may form another portion of the via 206 of the circuit board 200 of FIG. 2. The openings 911a and 911b and the vias 916a and 916b may combine to form the via 206 formed through the entire thickness t1 of the dielectric layer 204 of FIG. 2.

[0050] The vias may be filled with a metal material (808). Figure 9J illustrates an example of a structure 900J showing vias 916a and 916b filled with metal material 918a and 918b. In an embodiment, the vias may be filled using copper plating, which may leave a layer of metal material 918a and 918b on the dielectric material 914a and 914b and the outermost surfaces of vias 916a and 916b, as shown. However, one skilled in the art will understand that other techniques may be used to fill the vias 916a and 916b.

[0051] A second metal pad may be formed 810 on each of the vias, for example to form metal pads on an outermost surface of the circuit board. Figures 9K, 9L, 9M, 9N, 9O, 9P, and 9Q provide example structures at various points in the formation of the second metal pads.

[0052] As shown in Figure 9K, films 920a and 920b may be formed on the outermost surfaces (e.g., metals 918a and 918b) of structure 900J to form structure 900K, similar to the process described above with respect to Figure 9C. In an embodiment, the film may be a dry film, such as, for example, photoresist, formed using dry film lamination. However, one skilled in the art will appreciate that other methods, such as, for example, spin coating, may be used to form films 920a and 920b.

[0053] 9L, structure 900K may undergo an imaging or photolithography process that removes portions of films 920a and 920b in the regions between vias 916a and 916b to form structure 900L. In an embodiment, this may be done by placing patterns 922a and 922b, such as glass patterns, on structure 900K and exposing structure 900K to light (e.g., ultraviolet (UV) light) that is emitted through the pattern. This may result in the UV light hitting the portions of films 920a and 920b that are desired to be removed, or alternatively, the portions of films 920a and 920b that should not be removed.

[0054] As shown in FIG. 9M, desired portions of the films 920a and 920b can be removed, for example, by applying a developer to the structure 900L. A number of different types of developers can be used. In an embodiment, portions of the films 920a and 920b that were exposed to light in FIG. 9L can be made soluble to the developer, or portions of the films 920a and 920b that were not exposed to light in FIG. 9L can be made soluble to the developer. Exposing the structure 900L to the developer can result in the structure 900M having portions of the films 920a and 920b remaining over the vias 916a and 916b.

[0055] 9N, portions of metal layers 918a and 918b between remaining portions of membranes 920a and 920b may be removed to form structure 900N, which may be done, for example, by etching copper or other metal.

[0056] As shown in Figure 9O, the remaining portions of films 920a and 920b may be removed to form structure 900. This may be done, for example, by peeling away the remaining portions of films 920a and 920b.

[0057] 9P, a second metal pad 922a and 922b may be provided on each of the metal filled vias 918a and 918b. In an embodiment, this may be done using NiAu plating, although one skilled in the art will appreciate that other methods and / or metal materials may be used.

[0058] In embodiments where two circuit boards are manufactured simultaneously, the two circuit boards may be separated, as shown in Figure 9Q. Only one of the separated circuit boards 900Q is shown in Figure 9Q. The circuit board may then be ready for attachment of individual LED devices or monolithic LED arrays, for example, by soldering the metal pads of the individual LED devices or monolithic arrays to metal pads 922a and / or 922b of the circuit board.

[0059] Although the embodiments have been described in detail, those skilled in the art will appreciate that, given this specification, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept, and therefore, it is not intended that the scope of the invention be limited to the specific embodiments shown and described.

Claims

1. an aluminum nitride (AlN) carrier; a body on the AlN carrier; A stack of dielectric layers, a plurality of vias formed through an entire thickness of the stack of dielectric layers, the plurality of vias forming a plurality of pairs, adjacent pairs of the plurality of pairs being separated by a space having a width in the range of 20 μm to 200 μm; and a metallic material filling the plurality of vias; a body having a conductive pad on a top surface of each of the plurality of vias opposite the AlN carrier; a solder mask layer covering a top surface of the body opposite the AlN carrier, including the spaces between adjacent pairs of the plurality of vias and portions of the top surface of the stack of dielectric layers and the metallic material that are not covered by the conductive pads; A circuit board having

2. The circuit board of claim 1 , wherein each of the plurality of vias has a width in the range of 50 μm to 200 μm.

3. The circuit board of claim 1 , wherein the metallic material comprises one of copper, silver, and nickel.

4. The circuit board of claim 1 , wherein the stack of dielectric layers comprises an organic dielectric material.

5. 1. A light emitting diode (LED) lighting system comprising: A circuit board, an aluminum nitride (AlN) carrier; a stack of dielectric layers on the AlN carrier; a plurality of pairs of vias formed through an entire thickness of the stack of dielectric layers, adjacent pairs of the plurality of pairs being separated by a space having a width in the range of 20 μm to 200 μm; a metallic material filling the pairs of vias; a conductive pad on a top surface of each via of the plurality of pairs of vias opposite the AlN carrier; and a solder mask layer covering a top surface of the circuit board opposite the AlN carrier, including the spaces between adjacent pairs of the plurality of pairs of vias and portions of the top surfaces of the dielectric layer stack and metal material that are not covered by the conductive pads; A circuit board having a light emitting diode (LED) array on the circuit board; A system having

6. The LED array includes: A plurality of emitters; a pair of conductive pads electrically coupled to each of the plurality of emitters; 6. The system of claim 5, wherein the LED array is a monolithic LED array having

7. 7. The system of claim 6, wherein each of a plurality of pairs of conductive pads of the circuit board is electrically coupled to a respective one of the plurality of pairs of conductive pads electrically coupled to the plurality of emitters.

8. 6. The system of claim 5, wherein the LED array comprises a plurality of individual LED devices each having a pair of conductive pads, and each of the plurality of pairs of conductive pads of the circuit board is electrically coupled to the pair of conductive pads of a respective one of the plurality of individual LED devices.

9. The system of claim 5 , wherein each of the plurality of vias has a width in the range of 50 μm to 200 μm.

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