Multilayer circuit board and manufacturing method for a light emitting diode (LED) array packaged in close proximity

Abstract

This specification describes a multilayer circuit board and a method of manufacturing the same. The multilayer circuit board includes a top layer and a bottom layer. The top layer has an array of metal sections that are electrically insulated from each other. The metal sections at the periphery of the array extend to the outer periphery of the multilayer circuit board. The innermost metal section within the array is electrically and thermally coupled to the bottom layer by vias formed through all of the layers between the top layer and the bottom layer and the top layer.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 357,404, filed Jun. 30, 2022, the content of which is incorporated herein by reference.

Background Art

[0002] For example, in contrast to a single LED, an array of LED emitters (e.g., a 7×7 array) can be used, inter alia, to provide better lighting control for lighting applications. However, for optical design reasons (e.g., small light source size), miniaturization reasons, or other reasons, the overall size of a light source that can include one or more arrays of LED emitters may need to be minimized. Thus, some light sources can include a composite of multiple closely - packaged LEDs, or a single component composed of individually - addressable separated LED emitter zones, such as a square or rectangular configuration.

Summary of the Invention

[0003] This specification describes a multilayer circuit board and a manufacturing method. The multilayer circuit board includes a top layer and a bottom layer. The top layer has an array of metal sections that are electrically insulated from each other. The metal sections at the periphery of the array extend to the periphery of the multilayer circuit board. The innermost metal section within the array is electrically and thermally coupled to the bottom layer by a via formed through a layer between the top layer and the bottom layer and through all of the top layer.

Brief Description of the Drawings

[0004] A more detailed understanding can be obtained from the following description taken in conjunction with the accompanying drawings which are given by way of illustration:

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4

[0005] Examples of different lighting systems and / or the implementation of light-emitting diodes ("LEDs") are described in more detail below with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example can be combined with features found in one or more other examples to achieve additional implementations. Accordingly, it will be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only and are not intended to limit the present disclosure in any way. Like reference numerals refer to like elements throughout.

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

[0007] When an element such as a layer, region, or substrate is said to "on" or "onto" another element, it will be understood that it can be directly on or extend onto the other element, or intervening elements can also be present. In contrast, when an element is referred to as being "directly on" or "directly onto", there are no intervening elements. Also, when an element is referred to as being "connected" or "coupled" to another element, it will be understood that it can be directly connected or coupled to the other element, or it can 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", there are no intervening elements between that element and the other element. It will be understood that these terms are intended to encompass different directions of the elements in addition to any direction shown in the figures.

[0008] Relative terms such as "below," "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 illustrated. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation shown.

[0009] FIG. 1 is a top view of an exemplary LED array 102. In the example shown in FIG. 1, the LED array 102 is an array of emitters 120. The emitters 120 within the LED array 102 may be individually addressable or may be addressable within groups / subsets.

[0010] An exploded view of a 3×3 portion of the LED array 102 is also shown in FIG. 1. As shown in the exploded view of the 3×3 portion, the LED array 102 may include emitters 120 each having a width w1. The lanes 122 between the emitters 120 may have a width w2. The lanes 122 may provide a gap between adjacent emitters or may contain other materials. It should be understood that any widths and distances provided herein are for example only and actual widths and / or dimensions may vary.

[0011] FIG. 1 shows a light emitter disposed within a symmetric matrix, but it will be understood that light emitters of any shape and arrangement may be applied to the embodiments disclosed herein. For example, the LED array 102 of FIG. 1 can include a number of light emitters greater than 400 in any applicable arrangement, such as a 7×7 matrix, a 20×20 matrix, a symmetric matrix, an asymmetric matrix, etc. It will also be understood that multiple sets of light emitters, matrices, and / or substrates can be arranged in any applicable format to implement the embodiments disclosed herein. In some embodiments, the rows and columns can have different numbers of light emitters. An example of this is shown in FIG. 2A (described in detail below), where there are no light emitters at each of the outer corners of the array. One of ordinary skill in the art will recognize that different arrangements of light emitters may be used that are consistent with the embodiments described herein. It will be apparent that in the embodiments described herein, the number of layers within the multilayer circuit board determines the number of light emitters within the matrix, and vice versa. In other words, the number of layers that can be formed within the substrate may limit the number of light emitters within the matrix, and / or the number of light emitters within the matrix may determine the number of layers that must be included in the circuit board.

[0012] The controller can be coupled to selectively power a subgroup of the light emitters within the LED array. At least some of the light emitters within the LED array can be individually controlled. In other embodiments, groups or subgroups of light emitters can be controlled together. In some embodiments, the light emitters can have a distinct non-white color. For example, at least four light emitters can be an RGBY group of light emitters.

[0013] An LED array lighting fixture can include lighting fixtures and can be programmed to project different lighting patterns based on selective activation and intensity control of light emitters. Such lighting fixtures can provide multiple controllable beam patterns from a single lighting device without using moving parts. Typically, this is done by adjusting the brightness of individual LEDs in a 1D or 2D array. The optical system, whether shared or individual, can optionally direct light to a specific target area. In some embodiments, the height of the LEDs, their support substrates and electrical traces, and the associated micro-optics can be less than 5 millimeters, as low as about 2 mm, and / or can be on the order of 20 or 25 mm in size.

[0014] An LED array including LEDs, mini-LEDs, and / or μ-LED arrays can be used to selectively and adaptively illuminate a building or area to improve visual display and / or reduce lighting costs. Additionally, such LED arrays may be used to project media facades for decorative movement or video effects. With tracking sensors and / or cameras, selective illumination of areas around pedestrians may be possible. Different spectrally light emitters can be used to adjust the color temperature of the lighting and support wavelength specific horticultural illumination.

[0015] Street lighting is an important application that can greatly benefit from the use of LED arrays. A single type of light-emitting array can be used to mimic various streetlight types. For example, by appropriate activation or deactivation of selected emitters, it is possible to switch between a Type I linear streetlight and a Type IV semi-circular streetlight. Further, street lighting costs can be reduced by adjusting the intensity or distribution of the light beam according to environmental conditions or usage time. For example, when there are no pedestrians, the light intensity and distribution area can be decreased. If the emitters are spectrally distinct, the color temperature of the light can be adjusted according to the respective states of daylight, dusk, or night.

[0016] LED arrays are also well-suited to support applications that require direct or projection displays. For example, warning, emergency, or information signs can all be displayed or projected using LED arrays. This enables, for example, the projection of an exit sign that changes color or blinks. If the LED array contains a number of emitters, text information or numerical information can be provided. Direction arrows or similar indicators can also be provided.

[0017] Vehicle headlights are an LED array application that may require a large number of pixels and a high data refresh rate. Using automotive headlights that actively illuminate only a selected portion of the road can reduce problems related to glare or dazzling of oncoming drivers. For example, using an infrared camera as a sensor, the LED array can activate only the pixels necessary to illuminate the road and deactivate emitters that may dazzle pedestrians or oncoming vehicle drivers. Further, to improve the driver's environmental awareness, it is also possible to selectively illuminate pedestrians, animals, or signs outside the road. If the emitters are spectrally distinct, the color temperature of the light can be adjusted according to the respective states of daylight, dusk, or night. Some emitters can be used for optical wireless vehicle-to-vehicle communication.

[0018] One of the problems with LED arrays larger than 2×2 is routing a circuit board such as a printed circuit board (PCB) to enable individual addressing of the LEDs. Further, in many applications such as spotlights, torches, and mobile flashes, the power density may be relatively high (e.g., 1 to 10 W / mm 2 ). Thus, in addition to complex routing, in the case of high power density applications, good thermal design may be required to prevent overheating. The embodiments described herein provide a multilayer circuit board, such as a multilayer PCB, that can address both the addressing / routing and thermal challenges.

[0019] FIG. 2A is a plan view of an exemplary top layer 200a of a multilayer substrate of an embodiment. In the embodiment shown in FIG. 2A, the top layer 200a includes a plurality of metal sections 202 (only labeled 202a, 202b, and 202c for readability). Each of the metal sections 202 can be separated from any adjacent metal section 202 via an electrical insulation material 206. In some embodiments, the metal sections may be or may include copper or a copper alloy, and the insulation material may be epoxy.

[0020] Similar to the metal section 202, only some regions of the electrical insulating material 206 are labeled in FIG. 2A for ease of reading. In FIG. 2A, the metal sections are arranged as an array of metal sections. In the embodiment shown in FIG. 2A, a plurality of metal contacts 204 (only labeled 204a, 204b, 204c, 204d, 204e, 204f, and 204g for ease of reading) are provided on the metal section 202, and a single metal contact 204 can be arranged to be provided on each of the metal sections 202. As in the illustrated embodiment, depending on design constraints, contacts may not be present on all metal sections (e.g., corner portions or certain other metal sections 202 may be left uncontacted), or contacts may be present on all metal sections. As shown in FIG. 2A, the array of metal sections 202 may include a group of metal sections around the periphery of the array. In FIG. 2A, such metal sections include metal sections 202a, 202b, and 202c, as well as all metal sections outside the box 208. The box 208 indicates another group of metal sections 202 contained within the periphery of the array of metal sections.

[0021] As seen in FIG. 2A, the metal sections 202 around the periphery of the array of metal sections extend to the periphery of the multilayer circuit board (the outer edges of the layers shown in each of FIGS. 2A, 2B, 2C, and 2D). In some embodiments, the metal sections around the periphery of the array of metal sections may increase in surface area as they extend outwardly toward the periphery of the multilayer circuit board and may have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the metal sections may reach their maximum width before reaching the ends of the multilayer circuit board, and as shown, thinner or otherwise smaller regions of metal may be used such that the thermal and electrical connections extend to the periphery of the multilayer circuit board.

[0022] The metal sections can have a substantially triangular shape, for example, as shown in FIGS. 2A, 2B, 2C, and 2D, to maximize the amount of metal that can be allocated to each LED. For example, in FIG. 2A, the top layer 200a includes 28 metal sections 202. Each of the metal sections has a substantially triangular shape, and the vertex angle of each metal section is directed toward the center of layer 200a. The vertex angle can be approximately equal to 360° / 28, or about 13°. The section of the triangle opposite the vertex angle can be a straight line, or, as shown in FIGS. 2A, 2B, 2C, and 2D, can be slightly rounded so that all of the metal sections within the layer can form a circular-shaped metal with individual sections separated from other sections by an insulating material. As seen in FIG. 2A, in part or all of the layer, the vertex angle can deviate slightly from a triangular shape, for example, to better connect to individual LEDs, pads, or vias. Also, the vertex angle can deviate slightly so that not all of the metal sections have exactly the same vertex angle to better make thermal or electrical connections, or to provide a better fit within the circuit board. One or more minor angle changes and / or curvatures referred to herein are intended to fall within the scope of "substantially" triangular.

[0023] Although not visible in FIG. 2A, the top layer 200a can include one via passing through the circuit board layer 200a beneath each of the contacts 204 in the box 208. The end of each via extending through the top circuit board layer 200a is labeled 210 in FIG. 2B. The vias can be open or filled with a metal material such as copper, and thus the vias can establish electrical and thermal coupling with corresponding metal sections in the underlying circuit board layer. In some embodiments, the metal contacts 204 can be solder balls electrically coupled to the vias.

[0024] Figure 2B is a plan view of an exemplary first additional circuit board layer of the multilayer circuit board of the embodiment of Figure 2A. Similar to Figure 2A, the first additional circuit board layer 200b includes a plurality of metal sections 216 (labeled only 216a, 216b, and 216c for clarity). Each of the metal sections 216 can be separated from any adjacent metal section 216 via an electrical insulating material 212. Similar to the metal sections 216, for clarity, only some regions of the electrical insulating material 212 are labeled in Figure 2B.

[0025] As shown in Figure 2B, similar to Figure 2A, the array of metal sections 216 can include a group of metal sections around the periphery of the array. In Figure 2B, such metal sections include metal sections 216a, 216b, and 216c, as well as all metal portions outside the box 214. The box 214 represents another group of metal sections 216 included within the periphery of the array of metal sections. As seen in Figure 2B, similar to Figure 2A, the metal sections 216 around the periphery of the array of metal sections extend to the periphery of the multilayer circuit board (the outer edge of the layers shown in each of Figures 2A, 2B, 2C, and 2D). In some embodiments, the metal sections around the periphery of the array of metal sections may increase in surface area as they extend outwardly towards the periphery of the multilayer circuit board and may have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the metal sections may reach their maximum width before reaching the ends of the multilayer circuit board, and thinner or otherwise smaller regions of metal may be used such that the thermal and electrical connections extend to the periphery of the multilayer circuit board as shown.

[0026] As described above, the metal section can have a substantially triangular shape, for example, as shown in FIGS. 2A, 2B, 2C, and 2D, to maximize the amount of metal that can be allocated to each LED. For example, in FIG. 2B, layer 200b includes 20 metal sections 216. Each of the metal sections is substantially triangular in shape, and the apex angle of each metal section is directed towards the center of layer 200b. The apex angle may be approximately equal to 360° / 20, or about 18°. The section of the triangle opposite the apex angle may be straight, or may be slightly rounded such that, as shown in FIGS. 2A, 2B, 2C, and 2D, all of the metal sections within the layer form a circular-shaped metal having individual sections separated from other sections by an insulating material. As seen in FIG. 2B, in part or all of the layer, the apex angle may deviate slightly from a triangular shape, for example, to better connect to individual LEDs, pads, or vias. Also, the apex angle may deviate slightly such that not all of the metal sections have exactly the same apex angle to better make thermal or electrical connections, or to provide a better fit within the circuit board. One or more minor angle changes and / or curvatures referred to herein are intended to fall within the range of "substantially" triangular.

[0027] Although not visible in FIG. 2B, the first additional layer 200b may include one via passing through the circuit board layer 200b for each metal section 216 within the box 214. The terminus of each via extending through the top circuit board layer 200b is labeled 220 in FIG. 2C. The via may be open or filled with a metal material such as copper, and thus the via can establish an electrical and thermal connection with the corresponding metal section in the underlying circuit board layer. As can be seen from FIGS. 2A and 2B, no vias are formed under the metal contacts 204 around the periphery of the array of metal contacts shown in FIG. 2A. However, this may be acceptable or unacceptable in different designs depending on how electrical connections are made in a particular design.

[0028] Figure 2C is a plan view of an exemplary second additional layer 200c of the multilayer circuit board of the embodiments of FIGS. 2A and 2B. Similar to FIGS. 2A and 2B, the second additional circuit board layer 200c includes a plurality of metal sections 226 (only labeled 226a, 226b, and 226c for readability). Each of the metal sections 226 may be separated from any adjacent metal section 226 via an electrical insulating material 222. Similar to the metal sections 226, only some regions of the electrical insulating material 222 are labeled in FIG. 2C for readability.

[0029] As shown in FIG. 2C, similar to FIGS. 2A and 2B, the array of metal sections 226 may include a group of metal sections around the periphery of the array. In FIG. 2C, such metal sections include metal sections 226a, 226b, and 226c, as well as all metal portions outside of the box 224. The box 224 indicates another group of metal sections 226 that are included within the periphery of the array of metal sections. As can be seen from FIG. 2C, as seen in FIG. 2C, the metal sections 226 around the periphery of the array of metal sections extend to the periphery of the multilayer circuit board (the outer edge of the layer shown in each of FIGS. 2A, 2B, 2C, and 2D). In some embodiments, the metal sections around the periphery of the array of metal sections may increase in surface area as they extend outwardly towards the periphery of the multilayer circuit board and may have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the metal sections may reach their maximum width before reaching the ends of the multilayer circuit board, and as shown, thinner or otherwise smaller regions of metal may be used such that the thermal and electrical connections extend to the periphery of the multilayer circuit board.

[0030] As described above, the metal section can have a substantially triangular shape, for example, as shown in FIGS. 2A, 2B, 2C, and 2D, to maximize the amount of metal that can be allocated to each LED. For example, in FIG. 2C, layer 200c includes 12 metal sections 226. Each of the metal sections has a substantially triangular shape, and the apex angle of each metal section is directed toward the center of layer 200b. The apex angle may be approximately equal to 360° / 12, or about 30°. The section of the triangle on the opposite side of the apex angle may be a straight line, or, as shown in FIGS. 2A, 2B, 2C, and 2D, may be slightly rounded such that all of the metal sections within the layer form a circular-shaped metal having individual sections separated from other sections by an insulating material. As seen in FIG. 2C, in part or all of the layer, the apex angle may deviate slightly from a triangular shape, for example, to better make connections to individual LEDs, pads, or vias. Also, the apex angle may deviate slightly so that all metal sections do not necessarily have exactly the same apex angle, to better make thermal or electrical connections, or to provide a better fit within the circuit board. One or more minor angle changes and / or curvatures referred to herein are intended to fall within the range of "substantially" triangular.

[0031] Although not visible in FIG. 2C, the second additional layer 200c may include one via passing through the circuit board layer 200c for each metal section 226 within the box 224. The end of each via extending through the second additional circuit board layer 200c is labeled 234 in FIG. 2D. The vias may be open or filled with a metal material such as copper, and thus, the vias can establish electrical and thermal coupling with the corresponding metal sections in the underlying circuit board layer. As can be seen from FIGS. 2B and 2C, no vias are formed through the first additional circuit board layer 200b around the perimeter of the array of metal sections shown in FIG. 2B.

[0032] FIG. 2D is a plan view of an exemplary bottom layer 200d of the multilayer circuit board of the embodiments of FIGS. 2A, 2B, 2C, and 2D. Similar to FIGS. 2A, 2B, and 2C, the bottom circuit board layer 200d includes a plurality of metal sections 230 (only labeled 230a, 230b, and 230c for readability). Each of the metal sections 230 may be separated from any adjacent metal section 230 via an electrical insulating material 232. Similar to the metal sections 230, only some regions of the electrical insulating material 232 are labeled in FIG. 2D for readability.

[0033] As shown in FIG. 2D, since layer 200d is the bottommost layer of the multilayer circuit board, layer 200d includes four metal sections and shows only the four terminations of vias 234a, 234b, 234c, and 234d from the layer above (the second additional layer 200c shown in FIG. 2C). The metal sections 230 are similar to the metal sections around the periphery of the array of metal sections in each of FIGS. 2A, 2B, and 2C (the three layers above the lower layer 2D), and in some embodiments, the surface area increases as it extends outward toward the periphery of the multilayer circuit board and may have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the metal section may reach its maximum width before reaching the edge of the multilayer circuit board, and as shown, a thinner or otherwise smaller region of metal may be used so that the thermal and electrical connections extend to the periphery of the multilayer circuit board. As seen in FIGS. 2C and 2D, no vias are formed through the circuit board layer 200c in the metal sections 226 around the periphery of the array of metal sections 226. Further, although not shown, there may be no vias formed through the bottom layer 200d.

[0034] As described above, the metal section can have a substantially triangular shape, for example, as shown in FIGS. 2A, 2B, 2C, and 2D, to maximize the amount of metal that can be allocated to each LED. For example, in FIG. 2D, the bottom layer 200d includes four metal sections 230. Each of the metal sections is substantially triangular in shape, and the apex angle of each metal section tapers towards the center of layer 200d. The apex angle may be approximately equal to 360° / 4, or about 90°. The section of the triangle opposite the apex angle may be straight, or slightly rounded so that, as shown in FIGS. 2A, 2B, 2C, and 2D, all of the metal sections within the layer form a circular-shaped metal with individual sections separated from other sections by an insulating material. One or more minor angle changes and / or curvatures referred to herein are intended to fall within the scope of being "substantially" triangular.

[0035] Although not shown in FIGS. 2A, 2B, 2C, and 2D, the LED array may be mounted on a multilayer circuit board via contacts 204 on the top layer 200a. Thus, considering the structure of the multilayer circuit board described above with respect to FIGS. 2A, 2B, 2C, and 2D, each connected light emitter in the LED array mounted on the top layer 200a can have one dedicated metal section for optimal heat dissipation. In other words, in the top layer 200a, each of the light emitters outside the box 208 around the periphery of the array can have a dedicated metal section in the top layer 200a having a relatively large surface area. Moving from the periphery towards the center of the LED array, the next group of light emitters can have a dedicated metal section in the first additional layer 200B having a relatively large surface area. Continuing towards the center of the LED array, each successive group of light emitters can have a dedicated metal section in a lower layer. In the illustrated example, the next group of light emitters can have a dedicated metal section in the second additional layer 200C having a relatively large surface area. Each of the innermost light emitters of the LED array can have a dedicated metal section in the bottom layer 200D.

[0036] This can provide highly efficient and effective heat dissipation for a large array of LEDs. In particular, routing some of the LEDs to a lower layer that can be thermally coupled to individual large surface area metal sections can effectively provide an individual heat sink for each emitter in the array. Further, since each of the deeper layers is coupled to fewer emitters than the layer above it, the metal sections can be made to have a larger surface area the deeper into the multi-layer circuit board structure they go. This can allow the structure to compensate for the additional thermal resistance of the vias and can allow the surface area of the metal sections to be maximized without violating the electrical rules. Further, as shown in the figures, for optimizing the thermal design, each LED should be able to reach as much metal (e.g., PCB copper) as possible. In the illustrated example, this is achieved using a triangular metal or copper shape for each LED and can result in a pattern like a circular star as shown in the drawings, although those skilled in the art will understand that the basic shape can be varied in accordance with the description herein.

[0037] Four layers are shown in FIGS. 2A, 2B, 2C, and 2D, but the multi-layer circuit board can include any number of different layers consistent with the embodiments described herein. However, the amount of layers can be defined by the size of the LED array mounted on the circuit board. For example, for an array of N×N emitters, the multi-layer circuit board can have at least N / 2+1 layers. For an asymmetric light source of size N×M, the multi-layer circuit board can be defined by the minimum dimension. For example, if M < N, the multi-layer circuit board can have at least M / 2+1 layers.

[0038] This arrangement can provide excellent heat dissipation while also allowing for a relatively simple routing of electrical connections for the LED array. For example, when using a square 7×7 LED matrix as a light source, electrical connections for the light emitters can be made using a multilayer PCB as described above with respect to FIGS. 2A, 2B, 2C, 2D, or a multilayer PCB as described further below. For example, a square 7×7 matrix may require four layers to make the necessary electrical connections, while a 5×7 matrix may require three layers. For example, the outermost circle, square, or rectangle may be contacted at the top layer, and for example, the next inner circle, square, or rectangle of LEDs may be contacted to the next lower PCB layer using vias. This layer can also pass on the contacts necessary for the inner circle, square, or rectangle of LEDs, for example, to the layer below. This process may be repeated until reaching the (one or more) central light emitters. The overall shape and pattern of the metal sections are similar in each layer and can maximize the amount of metal dedicated to each light emitter.

[0039] Although not shown in the drawings, the heat sink may be arranged adjacent to the bottom layer 200d of the multilayer circuit board, either as a separate unit or incorporated into another circuit board such as a control board. In some embodiments, the multilayer PCB may be mounted on or cover the heat sink and may include intervening thermal or other layers, for example, to prevent short circuits.

[0040] FIG. 3 is a cross-sectional view along line a-a of FIG. 2A of the multilayer circuit board of FIGS. 2A, 2B, 2C, and 2D. As seen in FIG. 2A, line a-a is a line that cuts through the rows of light emitters in the illustrated LED array at one of the two innermost rows of LEDs in the array. In the illustrated example, the two innermost light emitters in a column are electrically coupled to contacts 204c and 204d, and are electrically and thermally contacted using vias 210d, 220d, and 234d, and 210c, 220c, and 234c, respectively, to route them thermally and electrically to the metal section of the bottom layer (only the metal layer 230c is labeled in FIG. 3). Moving to the right in FIG. 3, the next innermost light emitter in the row is electrically coupled to contact 204e, and is electrically and thermally contacted using vias 210e and 220e to route it thermally and electrically to the layer above the bottom layer (also referred to as metal section 226c). Moving further to the right in FIG. 3, the next innermost light emitter in the row is electrically coupled to contact 204f, and is electrically and thermally contacted using via 210f to route it thermally and electrically to the layer below it (also referred to as metal section 216c). Finally, the outermost light emitter in the column, which is electrically coupled to contact 204g, is directly attached to the metal portion 202c of the top layer of the multilayer circuit board.

[0041] FIG. 4 is a flowchart of an exemplary method of manufacturing a multilayer circuit board such as the multilayer circuit board of FIGS. 2A, 2B, 2C, 2D, and 3. In the example shown in FIG. 4, the method includes obtaining an LED array (402). The step of obtaining an LED array can include manufacturing the LED array or, alternatively, obtaining a fully or partially manufactured LED array. The number of layers of the multilayer circuit board can be determined (404). In some embodiments, this can be done by setting the number of layers to be N / 2 + 1 or more. N can be the number of rows in the array of LEDs. If the array is not square, N can be equal to the number of LEDs in the smaller of the two dimensions.

[0042] A multilayer circuit board having a determined number of layers can be obtained (406). The multilayer circuit board may have some or all of the characteristics of the multilayer circuit board described above with respect to FIGS. 2A, 2B, 2C, 2D, and 3. For example, the multilayer circuit board may include at least a top layer, a bottom layer, and at least one additional layer between the bottom and top layers. The top layer may include an array of metal sections electrically insulated from each other. The metal sections at the periphery of the array may extend to the periphery of the multilayer circuit board. Each of the innermost metal sections in the array may be electrically and thermally coupled to the bottom layer by vias formed through at least one additional layer between the top layer and the bottom layer and all of the top layer. Bonding pads may be disposed on each metal section. In some embodiments, obtaining the multilayer circuit board may include manufacturing the multilayer circuit board, such as by forming at least the top layer and the bottom layer and forming bonding pads on each of the metal sections of the top layer. In this case, manufacturing may include providing an insulating material between each of the metal sections. In some embodiments, obtaining may include obtaining a fully or partially manufactured multilayer circuit board and / or providing specifications for the multilayer circuit board for such manufacturing.

[0043] An array of LEDs may be mounted on the bonding pads (408). In some embodiments, the method may include forming a heat sink under the bottom layer. In some embodiments, each of the top layer and at least one additional layer includes an array of metal sections having a group of the metal sections around the periphery of the array extending to the periphery of the multilayer circuit board and a group of the metal sections included in the periphery of the array that are electrically and thermally coupled to at least one of the underlying integer number of layers. In some embodiments, for each of the at least one additional layer and the bottom layer, each of the metal sections in the group around the periphery of the array has a larger surface area than each of the metal sections in the group around the periphery of the array of the upper layer.

[0044] Although the present invention has been described in detail, those skilled in the art will understand that, considering this specification, modifications can be made to the embodiments described herein without departing from the spirit of the concept of the present invention. Therefore, the scope of the present invention is not intended to be limited to the specific embodiments illustrated and described.

Claims

1. A multilayer circuit board, comprising: a bottom layer; a top layer having an array of a plurality of metal sections electrically insulated from each other, wherein a plurality of the metal sections at a peripheral portion of the array extend to a peripheral portion of the multilayer circuit board; at least one additional layer between the bottom layer and the top layer; a plurality of vias, each of the plurality of vias extending through all of the at least one additional layer and the top layer between the top layer and the bottom layer, and electrically and thermally coupling an innermost metal section among the metal sections in the array to the bottom layer; A multilayer circuit board comprising the above.

2. The multilayer circuit board comprises at least an integer number of layers equal to at least N / 2 + 1, including the top layer, the bottom layer, and all of the at least one additional layer between the top layer and the bottom layer, where N is equal to the number of metal sections in the top layer. The multilayer circuit board according to Claim 1.

3. The at least one additional layer has an additional array of metal sections. The multilayer circuit board according to Claim 2.

4. For the at least one additional layer and the top layer between the top layer and the bottom layer, a group of the metal sections around the peripheral portion of the array extends to a peripheral portion of the multilayer circuit board, and a group of the metal sections included in the peripheral portion of the array is electrically and thermally coupled to at least one of the underlying layers. The multilayer circuit board according to Claim 3.

5. For the at least one additional layer and the bottom layer, each of the metal sections in the group of the metal sections around the peripheral portion of the array has a larger surface area than each of the metal sections in the group around the peripheral portion of the array of the layer above. The multilayer circuit board according to Claim 4.

6. The multilayer circuit board according to Claim 1, further comprising an insulating material between each of the metal sections in the array. The multilayer circuit board according to Claim 1.

7. The multilayer circuit board comprises a first circuit board layer, wherein the first circuit board layer, A first array of first metal sections, having an outer group of the first metal sections disposed around a peripheral portion of the first array and an inner group of the first metal sections included in the peripheral portion of the first array, each of the first metal sections within the first array being electrically insulated from each of the other first metal sections within the first array, and each of the first metal sections within the outer group extending to an outer peripheral portion of the first circuit board layer, the first array. A plurality of first vias formed through the first circuit board layer, each of the plurality of first vias being disposed under the inner group of the first metal sections and including metal, the plurality of first vias. The multilayer circuit board further comprises a second circuit board layer having a second array of second metal sections. The first circuit board layer is adjacent to the second circuit board layer, and the first metal sections within the inner group are electrically and thermally coupled to one of the second metal sections of the second circuit board layer via the plurality of first vias. Multilayer circuit board.

8. The multilayer circuit board further comprises a bonding pad array. Each of the bonding pads within the bonding pad array is disposed on one of the first metal sections. The multilayer circuit board according to claim 7.

9. The multilayer circuit board according to claim 8, further comprising an array of light emitting diodes (LEDs) coupled to the bonding pad array. The multilayer circuit board according to claim 8.

10. The second metal sections of the second circuit board layer include an outer group disposed around a peripheral portion of the second array and an inner group included in the peripheral portion of the second array. The second circuit board layer further comprises a plurality of second vias formed through the second circuit board layer, each of the plurality of second vias being disposed under the inner group of the second metal sections and including metal. The multilayer circuit board further comprises a third circuit board layer having a third array of third metal sections. The second circuit board layer is adjacent to the third circuit board layer, and the second metal sections within the inner group are electrically and thermally coupled to one of the third metal sections of the third circuit board layer via the plurality of second vias. The multilayer circuit board according to claim 7.

11. The multilayer circuit board further comprises at least one other circuit board layer adjacent to the third circuit board layer, wherein the at least one other circuit board layer comprises another array of a plurality of other metal sections, the other array comprising an outer group disposed around a periphery of the other array and an inner group contained within the periphery of the other array, the inner group being electrically and thermally coupled to the third circuit board layer or to one of the at least one other circuit board layers above, The multilayer circuit board according to claim 10.

12. The second metal section has a smaller surface area than the third metal section, The first metal section has a smaller surface area than the second metal section, The multilayer circuit board according to claim 10.

13. Each of the first metal section and the second metal section has a substantially triangular shape with an apex angle equal to 360° / N, where N is the number of metal sections in the layer, The multilayer circuit board according to claim 12.

14. The multilayer circuit board further comprises a heat sink adjacent to the lowermost circuit board layer of the multilayer circuit board, The multilayer circuit board according to claim 7.

15. A method of manufacturing a light emitting diode device (LED device), comprising the steps of obtaining an LED array; determining a number of layers for a multilayer circuit board, the number being at least N / 2 + 1, where N is an integer greater than 1 of the LEDs in the LED array; obtaining a multilayer circuit board having at least a top layer, a bottom layer, and at least one additional layer between the bottom layer and the top layer, the top layer having an array of metal sections electrically insulated from each other, the metal sections at a periphery of the array extending to a periphery of the multilayer circuit board, each of the innermost metal sections in the array being electrically and thermally coupled to the bottom layer by a via formed through all of the at least one additional layer and the top layer between the top layer and the bottom layer and a bonding pad disposed on each of the metal sections; mounting the LED array on the bonding pads. Method.

16. The step of obtaining the multi-layer circuit board includes manufacturing the multi-layer circuit board by forming at least the top layer and the bottom layer and forming the bonding pads on each of the metal sections of the top layer. The method according to claim 15.

17. The step of manufacturing the multi-layer circuit board includes providing an insulating material between each of the metal sections. The method according to claim 16.

18. The method further includes forming a heat sink under the bottom layer. The method according to claim 15.

19. Each of the top layer and the at least one additional layer includes an array of metal sections. The array of metal sections includes a group of metal sections around the periphery of the array extending to the periphery of the multi-layer circuit board, and a group of metal sections included in the periphery of the array that are electrically and thermally coupled to at least one of the underlying integer layers. The method includes an array of metal sections having The method according to claim 15.

20. For the at least one additional layer and the bottom layer, each of the metal sections in the group around the periphery of the array has a larger surface area than each of the metal sections in the group around the periphery of the array of the layer above. The method according to claim 19.

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