Multilayer circuit board for tight packaged light emitting

Abstract

Multilayer circuit boards and methods of manufacture are described herein. The multilayer circuit board includes a top layer and a bottom layer. The top layer includes an array of metal portions electrically insulated from each other. A metal portion at a periphery of the array extends to a periphery of the multilayer circuit board. The innermost metal portion in the array is electrically and thermally coupled to the bottom layer through vias formed through the entire top layer and any layer between the top layer and the bottom layer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 357,404, filed on June 30, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] For example, an array of LED emitters (e.g., a 7×7 array) can be used, among other things, to create better lighting control for lighting applications, as opposed to a single LED. However, for optical design reasons (e.g., small light source size), miniaturization reasons, or other reasons, it may be desirable to minimize the overall size of a light source that may include one or more arrays of LED emitters. Thus, some light sources may include a combination of multiple tightly packed LEDs, or a single component consisting of individually addressable discrete LED emitter areas, such as in a square or rectangular format. Summary of the invention

[0004] A multilayer circuit board and method of making the same are described herein. A multilayer circuit board includes a top layer and a bottom layer. The top layer includes an array of metal portions that are electrically insulated from each other. The metal portions at the periphery of the array extend to the periphery of the multilayer circuit board. The innermost metal portions in the array are electrically and thermally coupled to the bottom layer through vias formed through the entire top layer and any layers between the top layer and the bottom layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more detailed understanding may be obtained from the following description, which is given by way of example in conjunction with the accompanying drawings, in which:

[0006] Figure 1 is a top view of an example LED array;

[0007] Figure 2A is a top view of an example top layer of an example multi-layer circuit board;

[0008] Figure 2B yes Figure 2A A top view of an example first additional layer of an example multi-layer circuit board;

[0009] Figure 2C yes Figure 2A and Figure 2B A top view of an example second additional layer of an example multi-layer circuit board;

[0010] Figure 2D yes Figure 2A , Figure 2B , Figure 2C and Figure 2D a top view of an example bottom layer of an example multi-layer circuit board;

[0011] Figure 3is along Figure 2A The line aa in Figure 2A , Figure 2B , Figure 2C and Figure 2D A cross-sectional view of a multi-layer circuit board; and

[0012] Figure 4 Is the manufacture of multi-layer circuit boards (such as Figure 2A , Figure 2B , Figure 2C , Figure 2D and Figure 3 Flowchart of an example method for a multi-layer circuit board). DETAILED DESCRIPTION

[0013] Examples of different light illumination systems and / or light emitting diode ("LED") embodiments will be described more fully 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 embodiments. Therefore, it will be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only, and they are not intended to limit the present disclosure in any way. Like numbers refer to like elements throughout.

[0014] It will be understood that although the terms first, second, third, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms can be used to distinguish an element from another element. For example, the first element can be referred to as the second element and the second element can be referred to as the first element without departing from the scope of the present invention. As used herein, the term "and / or" can include any and all combinations of one or more associated listed items.

[0015] It will be understood that when an element such as a layer, region, or substrate is referred to as being "on" or "extending to" another element, it may be directly on or directly extending to another element, or there may also be intermediate elements. In contrast, when an element is referred to as being "directly on" or "directly extending to" another element, there may be no presence of intermediate elements. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to another element and / or connected or coupled to another element via one or more intermediate elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there is no presence of intermediate elements between the element and the other element. It will be understood that these terms are intended to cover different orientations of elements in addition to any orientation depicted in the figures.

[0016] 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 illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0017] Figure 1 is a top view of an example LED array 102. Figure 1 In the example shown in FIG. 1 , the LED array 102 is an array of emitters 120. The emitters 120 in the LED array 102 may be individually addressable or may be addressable in groups / clusters.

[0018] Figure 1 1. An exploded view of a 3×3 portion of LED array 102 is also shown in FIG. As shown in the exploded view of the 3×3 portion, LED array 102 can include emitters 120, each emitter 120 having a width w1. Channels 122 between emitters 120 can have a width w2. Channels 122 can provide air gaps between adjacent emitters, or can contain other materials. It will be understood that any widths and distances provided herein are merely examples, and that actual widths and / or dimensions can vary.

[0019] will understand that, despite Figure 1 , rectangular emitters arranged in a symmetrical matrix are shown, but emitters of any shape and arrangement may be applied to the embodiments described herein. Figure 1 The LED array 102 may include up to 400 or even more than 400 emitters in any suitable 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 groups of emitters, matrices, and / or panels may be arranged in any suitable form to implement the embodiments described herein. In some embodiments, rows and columns may have different numbers of emitters. An example of this is in Figure 2A (described in detail below), where there are no emitters in each of the outer corners of the array. One of ordinary skill in the art will recognize that different arrangements of emitters may be used consistent with the embodiments described herein. In the embodiments described herein, it will be apparent that the number of layers in a multi-layer circuit board will determine the number of emitters in the matrix, and vice versa. In other words, the number of layers that can be formed in the substrate can limit the number of emitters in the matrix, and / or the number of emitters in the matrix can determine the number of layers that must be included in the circuit board.

[0020] A controller may be coupled to selectively power subsets of emitters in the LED array. At least some of the emitters in the LED array may be individually controlled. In other embodiments, groups or subsets of emitters may be controlled together. In some embodiments, the emitters may have different non-white colors. For example, at least four of the emitters may be an RGBY emitter group.

[0021] LED array illuminators can include luminaires that can be programmed to project different lighting patterns based on selective emitter activation and intensity control. Such illuminators can use non-moving parts to deliver multiple controllable beam patterns from a single lighting device. Typically, this is done by adjusting the brightness of individual LEDs in a 1D or 2D array. Optionally, optics (whether shared or separate) can direct light onto specific target areas. In some embodiments, the height of the LEDs, their supporting substrates and electrical traces, and associated micro-optics can be less than 5 mm, as low as 2 mm, and / or as large as 20 or 25 mm.

[0022] LED arrays (including LED, Mini LED and / or μLED arrays) can be used to selectively and adaptively illuminate buildings or areas to improve visual displays or reduce lighting costs. In addition, such LED arrays can be used to project media facades for decorative motion or video effects. In combination with tracking sensors and / or cameras, selective illumination of areas around pedestrians may be possible. Spectrally distinct emitters can be used to adjust the color temperature of lighting, as well as to support specific wavelengths of horticultural lighting.

[0023] Street lighting is an important application that can greatly benefit from the use of LED arrays. A single type of LED array can be used to simulate various street light types, allowing, for example, switching between a Type I linear street light and a Type IV semi-circular street light by appropriately activating or deactivating the selected emitter. In addition, street lighting costs can be reduced by adjusting the beam intensity or distribution according to ambient conditions or time of use. For example, when there are no pedestrians, the light intensity and distribution area may be reduced. If the emitters are spectrally distinct, the color temperature of the light can be adjusted according to the corresponding day, dusk or night conditions.

[0024] LED arrays are also well suited for supporting applications that require direct or projected displays. For example, warning, emergency, or information signs can be displayed or projected using LED arrays. This allows, for example, exit signs that change color or flash to be projected. If the LED array includes a large number of emitters, text or numeric information can be presented. Directional arrows or similar indicators can also be provided.

[0025] Vehicle headlights are an LED array application that can require a large number of pixels and a high data refresh rate. Motor vehicle headlights that actively illuminate only selected portions of the road can be used to reduce problems associated with glare or blinding of oncoming drivers. Using an infrared camera as a sensor, the LED array can activate only those transmitters needed to illuminate the road, while deactivating transmitters that may dazzle pedestrians or drivers of oncoming vehicles. In addition, pedestrians, animals, or signs outside the road can be selectively illuminated to improve the driver's environmental awareness. If the transmitters are spectrally distinct, the color temperature of the light can be adjusted according to the corresponding day, dusk, or night conditions. Some transmitters can be used for optical wireless vehicle-to-vehicle communication.

[0026] One of the challenges of LED arrays larger than 2×2 is routing a circuit board, such as a printed circuit board (PCB), so that the LEDs are individually addressable. Additionally, for many applications, such as spotlights, flashlights, and mobile flashes, the power density may be relatively high (e.g., 1-10 W / mm 2 ). Therefore, in addition to complex routing, for high power density applications, good thermal design may be required to prevent overheating. The embodiments described herein provide a multi-layer circuit board (such as a multi-layer PCB) that can address both addressability / routing and thermal challenges.

[0027] Figure 2A 2 is a top view of an example top circuit board layer 200a of an example multi-layer circuit board. Figure 2A In the example shown in , top layer 200a includes multiple metal portions 202 (only 202a, 202b, and 202c are labeled for readability). Each metal portion 202 can be separated from any adjacent metal portion 202 via an electrically insulating material 206. In some embodiments, the metal portion can be or include copper or a copper alloy, and the insulating material can be an epoxy resin.

[0028] As with the metal portion 202, for readability, Figure 2A Only a few areas of the electrically insulating material 206 are marked. Figure 2A In the embodiment, the metal parts are arranged as an array of metal parts. Figure 2A In the example shown in , a plurality of metal contacts 204 (only 204a, 204b, 204c, 204d, 204e, 204f, and 204g are labeled for readability) are provided on metal portions 202, and may be arranged such that a single metal contact 204 is provided on each of metal portions 202. As in the example shown, depending on design constraints, there may not be a contact on every metal portion (e.g., a corner or some other metal portion 202 may remain free of contact), or there may be a contact on every metal portion. Figure 2AAs shown in , the array of metal portions 202 may include a set of metal portions surrounding the periphery of the array. Figure 2A In FIG. 2 , such metal portions include metal portions 202a, 202b, and 202c and all metal portions outside of box 208. Box 208 represents another set of metal portions 202 contained within the periphery of the metal portion array.

[0029] If you can Figure 2A As seen in FIG. 1 , the metal portion 202 surrounding the periphery of the metal portion array extends to the periphery of the multilayer circuit board (in FIG. Figure 2A , Figure 2B , Figure 2C and Figure 2D ). In some embodiments, the metal portions around the periphery of the array of metal portions can increase in surface area as they extend outward toward the periphery of the multilayer circuit board and have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the maximum width can be reached before the metal portions reach the end of the multilayer circuit board, and thinner or otherwise smaller metal areas can be used to extend thermal and electrical connections to the periphery of the multilayer circuit board, as shown.

[0030] The metal portion may have a substantially triangular shape, e.g. Figure 2A , Figure 2B , Figure 2C and Figure 2D to maximize the amount of metal that can be allocated to each LED. Figure 2A In FIG. 1 , the top layer 200a includes 28 metal portions 202. Each metal portion is substantially triangular in shape, wherein the vertex of each metal portion points toward the center of the layer 200a. The vertex angle may be approximately equal to 360° / 28 or approximately 13°. The triangular portion opposite the vertex angle may be straight or as shown in FIG. Figure 2A , Figure 2B , Figure 2C and Figure 2D As shown in FIG, the metal parts in a layer are slightly rounded so that all metal parts in a layer can form a circular metal, where the parts are separated from each other by insulating material. Figure 2A As can be seen in the Figures, the shape of the vertex angles can also deviate slightly from a triangle in some or all layers, for example to better connect to individual LEDs, pads, or vias. The vertex angles can also deviate slightly so that not all metal parts have exactly the same vertex angles, to allow for better thermal or electrical connections, or to provide better assembly within a circuit board. Minor angle variations and / or bends (such as one or more of those mentioned in this paragraph) are intended to fall within the scope of being "substantially" triangular.

[0031] Although in Figure 2AAlthough they may not be visible in the figure, the top layer 200a may include a via through the circuit board layer 200a below each contact 204 within the box 208. Each via extending through the top circuit board layer 200a terminates at Figure 2B The through hole can be open or filled with a metal material (such as copper) so that the through hole can establish electrical and thermal coupling with a corresponding metal portion in the circuit board layer below it. In some embodiments, the metal contact 204 can be a solder ball electrically coupled to the through hole.

[0032] Figure 2B yes Figure 2A A top view of an example first additional circuit board layer 200b of an example multi-layer circuit board. Figure 2A , the first additional circuit board layer 200b includes a plurality of metal portions 216 (only 216a, 216b, and 216c are labeled for readability). Each metal portion 216 may be separated from any adjacent metal portion 216 by an electrically insulating material 212. As with the metal portions 216, for readability, Figure 2B Only a few areas of electrically insulating material 212 are marked.

[0033] like Figure 2B shown in and with Figure 2A Similarly, the array of metal portions 216 may include a set of metal portions surrounding the periphery of the array. Figure 2B In FIG. 1 , such metal portions include metal portions 216a, 216b, and 216c and all metal portions outside of box 214. Box 214 represents another set of metal portions 216 contained within the periphery of the metal portion array. Figure 2B It can be seen that similar to Figure 2A The metal portion 216 surrounding the periphery of the metal portion array extends to the periphery of the multilayer circuit board (at Figure 2A , Figure 2B , Figure 2C and Figure 2D ). In some embodiments, the metal portions around the periphery of the array of metal portions can increase in surface area as they extend outward toward the periphery of the multilayer circuit board and have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the maximum width can be reached before the metal portions reach the end of the multilayer circuit board, and thinner or otherwise smaller metal areas can be used to extend thermal and electrical connections to the periphery of the multilayer circuit board, as shown.

[0034] As mentioned above, the metal portion may have a substantially triangular shape, e.g. Figure 2A , Figure 2B , Figure 2C and Figure 2Dto maximize the amount of metal that can be allocated to each LED. Figure 2B In the embodiment, layer 200b includes 20 metal portions 216. Each metal portion is substantially triangular in shape, wherein the vertex of each metal portion points toward the center of layer 200b. The vertex angle may be approximately equal to 360° / 20 or approximately 18°. The triangular portion opposite the vertex angle may be straight or as shown in FIG. Figure 2A , Figure 2B , Figure 2C and Figure 2D As shown in the figure, the metal parts in one layer are slightly rounded so that all the metal parts in one layer can form a circular metal, where the individual parts are separated from each other by insulating material. Figure 2B As can be seen in the Figures, the shape of the vertex angles can also deviate slightly from a triangle in some or all layers, for example to better connect to individual LEDs, pads, or vias. The vertex angles can also deviate slightly so that not all metal parts have exactly the same vertex angles, to allow for better thermal or electrical connections, or to provide better assembly within a circuit board. Minor angle variations and / or bends (such as one or more of those mentioned in this paragraph) are intended to fall within the scope of being "substantially" triangular.

[0035] Although in Figure 2B Although they may not be visible in the figure, the first additional layer 200b may include a via through the circuit board layer 200b for each metal portion 216 within the box 214. Each via extending through the top circuit board layer 200b terminates at Figure 2C The through hole can be open or filled with a metal material (such as copper) so that the through hole can establish electrical and thermal coupling with the corresponding metal part in the circuit board layer below it. Figure 2A and Figure 2B It can be seen that in Figure 2A There are no vias formed underneath the metal contacts 204 around the periphery of the metal contact array shown in FIG. However, in different designs, this may or may not be allowed, depending on how the electrical connections are made in a particular design.

[0036] Figure 2C yes Figure 2A and Figure 2B A top view of an example second additional layer 200c of an example multilayer circuit board. Figure 2A and Figure 2B , the second additional circuit board layer 200c includes a plurality of metal portions 226 (only 226a, 226b, and 226c are labeled for readability). Each metal portion 226 can be separated from any adjacent metal portion 226 by an electrically insulating material 222. As with the metal portions 226, for readability, Figure 2COnly a few areas of electrically insulating material 222 are marked.

[0037] like Figure 2C shown in and with Figure 2A and Figure 2B Similarly, the array of metal portions 226 may include a set of metal portions surrounding the periphery of the array. Figure 2C In FIG. 1 , such metal portions include metal portions 226a, 226b, and 226c and all metal portions outside of box 224. Box 224 represents another set of metal portions 226 contained within the periphery of the metal portion array. Figure 2C It can be seen that similar to Figure 2A and Figure 2B The metal portion 226 surrounding the periphery of the metal portion array may extend to the periphery of the multilayer circuit board (in Figure 2A , Figure 2B , Figure 2C and Figure 2D ). In some embodiments, the metal portions around the periphery of the array of metal portions can increase in surface area as they extend outward toward the periphery of the multilayer circuit board and have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the maximum width can be reached before the metal portions reach the end of the multilayer circuit board, and thinner or otherwise smaller metal areas can be used to extend thermal and electrical connections to the periphery of the multilayer circuit board, as shown.

[0038] As mentioned above, the metal portion may have a substantially triangular shape, e.g. Figure 2A , Figure 2B , Figure 2C and Figure 2D to maximize the amount of metal that can be allocated to each LED. Figure 2C In the embodiment, layer 200c includes 12 metal portions 226. Each metal portion is substantially triangular in shape, wherein the vertex of each metal portion points toward the center of layer 200b. The vertex angle may be approximately equal to 360° / 12 or approximately 30°. The triangular portion opposite the vertex angle may be straight or as shown in FIG. Figure 2A , Figure 2B , Figure 2C and Figure 2D As shown in the figure, the metal parts in one layer are slightly rounded so that all the metal parts in one layer can form a circular metal, where the individual parts are separated from each other by insulating material. Figure 2CAs can be seen in the Figures, the shape of the vertex angles can also deviate slightly from a triangle in some or all layers, for example to better connect to individual LEDs, pads, or vias. The vertex angles can also deviate slightly so that not all metal parts have exactly the same vertex angles, to allow for better thermal or electrical connections, or to provide better assembly within a circuit board. Minor angle variations and / or bends (such as one or more of those mentioned in this paragraph) are intended to fall within the scope of being "substantially" triangular.

[0039] Although in Figure 2C Although they may not be visible in the figure, the second additional layer 200c may include a via through the circuit board layer 200c for each metal portion 226 within the block 224. Each via extending through the second additional circuit board layer 200c has a terminal end at Figure 2D The through hole can be open or filled with a metal material (such as copper) so that the through hole can establish electrical and thermal coupling with the corresponding metal part in the circuit board layer below it. Figure 2B and Figure 2C It can be seen that in Figure 2B No through holes penetrating the first additional circuit board layer 200b are formed around the periphery of the metal portion array shown in FIG.

[0040] Figure 2D yes Figure 2A , Figure 2B , Figure 2C and Figure 2D A top view of an example bottom layer 200d of an example multilayer circuit board. Figure 2A , Figure 2B and Figure 2C , the bottom circuit board layer 200d includes a plurality of metal portions 230 (only 230a, 230b, and 230c are labeled for readability). Each metal portion 230 may be separated from any adjacent metal portion 230 by an electrically insulating material 232. As with the metal portions 230, for readability, Figure 2D Only a few areas of electrically insulating material 232 are marked.

[0041] like Figure 2D As shown in FIG. 1 , since layer 200d is the bottom layer of the multi-layer circuit board, layer 200d includes only four metal parts, and only the metal parts from the upper layer ( Figure 2C The metal portion 230 is similar to the four terminals of the through holes 234a, 234b, 234c and 234d of the second additional layer 200c). Figure 2A , Figure 2B and Figure 2C Each of the Figure 2DIn some embodiments, the metal portions around the periphery of the array of metal portions (three layers above the bottom layer) can increase in surface area as they extend outward toward the periphery of the multilayer circuit board and have a maximum width at the periphery of the multilayer circuit board. However, in some embodiments, the maximum width can be reached before the metal portions reach the end of the multilayer circuit board, and thinner or otherwise smaller metal areas can be used to extend thermal and electrical connections to the periphery of the multilayer circuit board, as shown. As shown in Figure 2C and Figure 2D It can be seen that no through-holes are formed through the circuit board layer 200c in the metal portion 226 around the periphery of the array of metal portions 226. Additionally, although not shown in the figure, there may be no through-holes formed through the bottom layer 200d.

[0042] As mentioned above, the metal portion may have a substantially triangular shape, e.g. Figure 2A , Figure 2B , Figure 2C and Figure 2D to maximize the amount of metal that can be allocated to each LED. Figure 2D In the embodiment, the bottom layer 200d includes four metal portions 230. Each metal portion is substantially triangular in shape, wherein the vertex of each metal portion points to the center of the layer 200d. The vertex angle may be approximately equal to 360° / 4 or approximately 90°. The triangular portion opposite to the vertex angle may be straight or Figure 2A , Figure 2B , Figure 2C and Figure 2D The slightly rounded shape shown in FIG. 5 is a circle shaped metal with the individual parts separated from each other by insulating material. Minor angle changes and / or bends (such as one or more of those mentioned herein) are intended to fall within the scope of "substantially" triangular.

[0043] Although not in Figure 2A , Figure 2B , Figure 2C and Figure 2D , but the LED array can be mounted to a multilayer circuit board via contacts 204 on the top layer 200a. Figure 2A , Figure 2B , Figure 2C and Figure 2DFor the described structure of the multilayer circuit board, each connected emitter in the LED array mounted on the top layer 200a can have a dedicated metal portion for optimal heat dissipation. In other words, in the top layer 200a, each emitter outside the box 208 around the perimeter of the array can have a dedicated metal portion in the top layer 200A that has a relatively large surface area. Moving from the perimeter of the LED array towards the middle, the next group of emitters can have a dedicated metal portion in the first additional layer 200B that has a relatively large surface area. Continuing to move towards the middle of the LED array, each next group of emitters can have a dedicated metal portion in the underlying layer. In the example shown, the next group of emitters can have a dedicated metal portion in the second additional layer 200C that has a relatively large surface area. Each innermost emitter in the LED array can have a dedicated metal portion in the bottom layer 200D.

[0044] This can provide extremely efficient and effective heat dissipation for large LED arrays. In particular, routing some of the LEDs to lower layers where they can be thermally coupled to separate large surface area metal portions can effectively provide individual heat dissipation for each emitter in the array. Additionally, since each deeper layer is coupled to fewer emitters compared to the layer above it, the metal portions can be made to have a larger surface area, thus moving deeper into the multilayer circuit board structure. This can enable the structure to compensate for the increased thermal resistance of the vias and can enable the surface area of the metal portions to be maximized without violating electrical rules. Additionally, as shown in the figure, for optimized thermal design, each LED should be able to contact as much metal (e.g., PCB copper) as possible. In the example shown, this is achieved using a triangular metal or copper shape for each LED, which can result in a circular star pattern as shown in the figure, although those of ordinary skill in the art will understand that the basic shape can be modified in accordance with the description herein.

[0045] Although four layers are shown in Figure 2A 、 Figure 2B 、 Figure 2C and Figure 2D the multilayer circuit board can include any number of different layers consistent with the embodiments described herein. However, the number of layers can be defined by the size of the LED array to be mounted on the circuit board. For example, for an array of N×N emitters, the multilayer circuit board can have at least N / 2 + 1 layers. For an asymmetric light source of size N×M, the multilayer circuit board can be defined by the smaller dimension. For example, if M < N, the multilayer circuit board can have at least M / 2 + 1 layers.

[0046] While this arrangement can provide excellent heat dissipation, it can also make the wiring for the electrical connections of the LED array relatively simple. For example, if a square 7×7 LED matrix is ​​used as the light source, a multi-layer PCB (such as the one described above) can also be used. Figure 2A , Figure 2B , Figure 2C and Figure 2D and further described below) to make electrical connections for the emitters. For example, a square 7×7 matrix may require 4 layers to make the required electrical connections, while a 5×7 matrix may require 3 layers. For example, the outermost circle, square, or rectangle can be contacted on the top layer, for example, and the next inner LED circle, square, or rectangle can be contacted using vias to the next lower PCB layer. This layer can also pass the required contacts for the inner LED circle, square, or rectangle to the layer below. This process can be repeated until the (one or more) center emitters are reached. The general shape and pattern of the metal parts can be similar in each layer to maximize the amount of metal that can be dedicated to each emitter.

[0047] Although not shown in the figure, a heat sink (whether separate or incorporated into another circuit board (such as a control board)) can be located near the bottom layer 200d of the multilayer circuit board. In some embodiments, the multilayer PCB can be mounted on or above the heat sink and can include intervening thermal or other layers, for example to prevent short circuits.

[0048] Figure 3 is along Figure 2A The line aa in Figure 2A , Figure 2B , Figure 2C and Figure 2D A cross-sectional view of a multi-layer circuit board. Figure 2A As can be seen in FIG. 1 , line aa cuts through an entire row of emitters in one of the two innermost rows of LEDs in the array in the illustrated LED array. In the illustrated example, the two innermost emitters in the row (i.e., the emitters electrically coupled to contacts 204c and 204d) are electrically and thermally contacted using vias 210d, 220d, and 234d and 210c, 220c, and 234c, respectively, thereby routing them thermally and circuitically to the underlying metal portion (at Figure 3 Only metal layer 230c is marked in FIG. Figure 3 Towards the right in the middle, the next innermost emitter in the row, which is electrically coupled to contact 204e, makes electrical and thermal contact using vias 210e and 220e, thereby routing its thermal and electrical circuits to a layer above the bottom layer (also referred to as metal portion 226c). Figure 3Further to the right in the figure, the next innermost emitter in the row, electrically coupled to contact 204f, is electrically and thermally contacted using via 210f, thereby routing its thermal and electrical circuits to the layer below it (also referred to as metal portion 216c). Finally, the outermost emitter in the row, electrically coupled to contact 204g, is mounted directly to metal portion 202c of the top layer of the multilayer circuit board.

[0049] Figure 4 Is the manufacture of multi-layer circuit boards (such as Figure 2A , Figure 2B , Figure 2C , Figure 2D and Figure 3 A flowchart of an example method 400 of a multi-layer circuit board). Figure 4 In the example shown in , the method includes obtaining an LED array (402). The obtaining may include manufacturing the LED array or otherwise obtaining a fully or partially manufactured LED array. The number of layers of the multi-layer circuit board may be determined (404). In some embodiments, this may be accomplished by setting the number of layers to be equal to or greater than N / 2+1. N may be the number of rows in the LED array. Where the array is not square, N may be equal to the number of LEDs in the smaller of the two dimensions.

[0050] A multilayer circuit board having the determined number of layers may be obtained (406). The multilayer circuit board may have the Figure 2A , Figure 2B , Figure 2C , Figure 2D and Figure 3 Some or all of the features of the multilayer circuit board described herein. For example, the multilayer circuit board may include at least a top layer, a bottom layer, and at least one additional layer between the top layer and the bottom layer. The top layer may include an array of metal portions that are electrically insulated from each other. The metal portions at the periphery of the array may extend to the periphery of the multilayer circuit board. Each innermost metal portion in the array may be electrically and thermally coupled to the bottom layer through a through hole formed through the entire top layer and at least one additional layer between the top layer and the bottom layer. A bonding pad may be provided on each metal portion. In some embodiments, obtaining the multilayer circuit board may include manufacturing it, such as by forming at least a top layer and a bottom layer, and forming a bonding pad on each metal portion of the top layer. In this case, the manufacturing may include providing an insulating material between each metal portion. In some embodiments, the obtaining may include obtaining a fully or partially manufactured multilayer circuit board and / or providing specifications for a multilayer circuit board for such manufacturing.

[0051] The LED array can be mounted to the bonding pads (408). In some embodiments, the method can include forming a heat sink under the bottom layer. In some embodiments, each of the top layer and the at least one additional layer can include an array of metal portions, wherein a set of metal portions around a periphery of the array extends to a periphery of the multilayer board, and a set of metal portions contained within the periphery of the array are electrically and thermally coupled to at least one of the integer number of layers below it. In some embodiments, for each of the bottom layer and the at least one additional layer, each metal portion in the set around the periphery of the array has a greater surface area than each metal portion in the set around the periphery of the array of the layer above it.

[0052] Having described the embodiments in detail, those skilled in the art will appreciate that, given this description, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept. Therefore, it is intended that the scope of the invention not be limited to the specific embodiments illustrated and described.

Claims

1. A multilayer circuit board, comprising: bottom layer; a top layer comprising an array of metal portions electrically insulated from one another, a plurality of metal portions at a periphery of the array extending to a periphery of the multilayer circuit board; at least one additional layer between the bottom layer and the top layer; and A plurality of vias, each via extending through the entire top layer and at least one additional layer between the top layer and the bottom layer, and electrically and thermally coupling an innermost metal portion of the metal portions in the array to the bottom layer.

2. A multilayer circuit board according to claim 1, wherein the multilayer circuit board comprises an integer number of layers, the integer number of layers comprising a top layer, a bottom layer, and at least one additional layer between the top layer and the bottom layer, and the integer is at least equal to N / 2+1, wherein N is equal to the number of metal parts in the top layer.

3. The multilayer circuit board of claim 2, wherein the at least one additional layer comprises an additional array of metal portions.

4. The multilayer circuit board according to claim 3, wherein: For the top layer and at least one additional layer between the top and bottom layers, a set of metal portions surrounding the periphery of the array extends to the periphery of the multilayer board, and a set of metal portions contained within the periphery of the array is electrically and thermally coupled to at least one layer below it.

5. The multilayer circuit board according to claim 4, wherein: For the bottom layer and at least one additional layer, the surface area of ​​each metal portion in the set of metal portions around the periphery of the array is greater than the surface area of ​​each metal portion in the set around the periphery of the array of the layer above it.

6. The multilayer circuit board of claim 1, further comprising an insulating material between each metal portion in the array.

7. A multilayer circuit board comprising: The first circuit board layer includes: a first array of first metal portions, comprising an outer group of first metal portions arranged around a periphery of the first array and an inner group of first metal portions contained within the periphery of the first array, each first metal portion in the first array being electrically isolated from each other first metal portion in the first array, and each first metal portion in the outer group extending to the periphery of the first circuit board layer, and a plurality of first vias formed through the first circuit board layer, each of the plurality of first vias being disposed below an inner group of the first metal portions and containing metal; and a second circuit board layer including a second array of second metal portions, The first circuit board layer is adjacent to the second circuit board layer, wherein the first metal portion in the inner group is electrically and thermally coupled to one of the second metal portions in the second circuit board layer via a plurality of first vias.

8. The multilayer circuit board of claim 7, further comprising an array of bonding pads, each bonding pad in the array being disposed on a corresponding one of the first metal portions.

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

10. The multi-layer circuit board according to claim 7, wherein: The second metal portion in the second circuit board layer includes an outer group arranged around a periphery of the second array and an inner group contained within the periphery of the second array, The second circuit board layer also includes a plurality of second vias formed through the second circuit board layer, each of the plurality of second vias being disposed below the inner group of the second metal portions and containing metal, The circuit board also includes a third circuit board layer including a third array of third metal portions, and The second circuit board layer is adjacent to the third circuit board layer, wherein the second metal portion in the inner group is electrically and thermally coupled to one of the third metal portions in the third circuit board layer via a plurality of second vias.

11. The multilayer circuit board according to claim 10 further includes at least one other circuit board layer adjacent to the third circuit board layer, the at least one other circuit board layer including other arrays of multiple other metal parts, the multiple other metal parts including an external group arranged around the periphery of the other array and an internal group contained within the periphery of the other array, and electrically and thermally coupled to the third circuit board layer or one of the at least one other circuit board layers above it via the internal group. 12 . The multilayer circuit board according to claim 10 , wherein the second metal portion has a smaller surface area than the third metal portion, and the first metal portion has a smaller surface area than the second metal portion.

13. The multilayer circuit board of claim 12, wherein each of the first metal portion and the second metal portion has a substantially triangular shape with a vertex angle equal to 360° / N, where N is the number of metal portions in the layer.

14. The multi-layer circuit board of claim 7, further comprising a heat sink adjacent to a lowermost circuit board layer of the multi-layer circuit board.

15. A method of manufacturing a light emitting diode (LED) device, the method comprising: Obtaining an LED array; Determining the number of layers of the multilayer circuit board to be greater than or equal to N / 2+1, where N is an integer greater than one LED in the LED array; obtaining a multilayer circuit board, the multilayer circuit board comprising at least a top layer, a bottom layer, and at least one additional layer between the top layer and the bottom layer, the top layer comprising an array of metal portions electrically insulated from one another, the metal portions at the periphery of the array extending to the periphery of the multilayer circuit board, each innermost metal portion in the array being electrically and thermally coupled to the bottom layer via a via formed through the entire top layer and the at least one additional layer between the top layer and the bottom layer, and a bonding pad being disposed on each metal portion; and Mount the LED array to the bonding pads.

16. The method of claim 15, wherein obtaining the multi-layer circuit board comprises manufacturing the multi-layer circuit board by forming at least a top layer and a bottom layer and forming a bonding pad on each metal portion of the top layer.

17. The method of claim 16, wherein manufacturing the multi-layer circuit board includes providing an insulating material between each metal portion.

18. The method of claim 15, further comprising forming a heat sink below the bottom layer.

19. The method of claim 15, wherein each of the top layer and the at least one additional layer comprises an array of metal portions, wherein a set of metal portions surrounding the periphery of the array extends to the periphery of the multilayer board, and wherein the set of metal portions contained within the periphery of the array are electrically and thermally coupled to at least one of the integer number of layers therebelow.

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

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