Abstract:
In certain embodiments there is provided a blank for a printed circuit board and methods pertaining to same. In some embodiments, the blank is provided in a generally straight configuration and is capable of being deformed in-plane into a bent configuration, such as, but not limited to, a generally ring-shaped configuration, a generally square shape, or a generally S-shape. In some embodiments, the PCB is used with a lighting fixture and is populated with light emitting diodes.

Description:
FIELD OF THE INVENTION  
       [0001]    The invention generally relates to bent printed circuit boards and methods pertaining to same. 
       BACKGROUND OF THE INVENTION  
       [0002]    Light emitting diodes (“LEDs”) are sometimes used in lighting fixtures as an alternative to more traditional light sources. When used in such fixtures, the LEDs are typically mounted on, and electrically connected to, a printed circuit board (“PCB”). Metal-core PCBs (“MCPCB”) (also known as integrated metal substrates (“IMS”)) are sometimes used in such applications. A MCPCB includes a metal (e.g., aluminum) base (as opposed to the traditional fiberglass base) onto which a dielectric layer is applied. A layer of copper is positioned on top of the dielectric layer. The LEDS are positioned on the copper layer, which acts as a circuit layer for electrical connections. 
         [0003]    Metal core blanks (i.e., onto which the traces are created during fabrication and onto which the components are placed during assembly) are available in only a few predetermined sizes, such as 18 inches by 24 inches. These available sizes oftentimes are not compatible with the dimensions or design of the lighting fixtures in which the MCPCBs will be used. Rather, incorporation of a board in a fixture often requires that the dimensions of the board be tailored to accommodate the dimensions of the lighting fixture. Most commonly, this requires that portions of the board be trimmed away, resulting in waste of the board material. 
         [0004]    By way only of example, MCPCBs may be used in recessed dome-shaped fixtures. The fixtures generally require use of a ring-shaped PCB with the LEDs arranged in a circle along the board. To create such a board, the excess material is removed during fabrication to create a circular PCB. The LEDs are mounted on the board in a circle. In some cases, over half of the surface area of the pre-formed metal-core board is discarded, and thus wasted, as a result of this process. 
       SUMMARY OF THE INVENTION  
       [0005]    In certain embodiments there is provided a PCB that is capable of being bent in-plane into a desired shape and retaining itself in the shape. In some embodiments, the blank is a long relatively narrow strip formed of repeating units connected by bridges that is configured to he deformed into a generally ring-shaped configuration or other desired configuration. 
         [0006]    The terms “invention,” “the invention,” “this invention” and “the present invention” used in this patent are intended to refer broadly to all of the subject matter of this patent and the patent claims below. Statements containing these terms should not be understood to limit the subject matter described herein or to limit the meaning or scope of the patent claims below. Embodiments of the invention covered by this patent are defined by the claims below, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to the entire specification of this patent, all drawings and each claim. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES  
         [0007]    Illustrative embodiments of the present invention are described in detail below with reference to the following drawing figures: 
           [0008]      FIG. 1  is a top view of a printed circuit board according to one embodiment, shown in a generally straight configuration. 
           [0009]      FIG. 2  is a top view of the board of  FIG. 1 , shown in a bent configuration. 
           [0010]      FIG. 3  is a top view of a repeating unit of a board according to another embodiment. 
           [0011]      FIG. 4  is a top view of a board made up of the repeating unit of  FIG. 3 , the board shown in a bent configuration. 
           [0012]      FIG. 5  is a perspective view of a printed circuit board according to another embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    The subject matter of embodiments of the present invention is described here with specificity to meet statutory requirements, but this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be interpreted as implying any particular order or arrangement among or between various steps or elements except when the order of individual steps or arrangement of elements is explicitly described. 
         [0014]      FIG. 1  illustrates a printed circuit board  10  according to one embodiment. In this particular embodiment, the board  10  is provided as an elongate, linear strip. However, the board  10  may be of any size and shape and is not limited to the linear board shown in  FIG. 1 . The board  10  can be provided in the desired size and shape by routing, milling, punching, die stamping, or using any suitable technique. 
         [0015]    As shown in the embodiment of  FIG. 1 , the board  10  is made up of a plurality of repeating units  13 . Board  10  has a top surface  20  and a bottom surface  22 . An LED  12  is mounted on each repeating unit  13  and copper traces are printed on the top surface of the board to electrically interconnect the LEDs  12 . Any number of LEDs  12  may be mounted on a repeating unit  13  or, alternatively, no LEDs may be provided on some of the repeating units  13 . Board  10  may support any type of LED and the LEDs may be attached to board  10  in any suitable way, such as, but not limited to, using chip-on-board technology (i.e., direct die attachment), surface mounting, or through-hole attachment. Board  10  may be populated with LEDs  12  either before or after the board is deformed into its bent configuration, as discussed below. 
         [0016]    The repeating units  13  are designed and connected to permit in-plane deformation or bending of the board  10 , as seen in  FIG. 2 . As shown in  FIG. 1 , adjacent units  13  are connected via a connector or bridge  15 , although adjacent units may be connected in any suitable way. 
         [0017]    Board  10  is capable of being deformed into a generally bent configuration, as shown in  FIG. 2 . In some embodiments, as shown in  FIG. 2 , board  10  is bent into a generally ring-shaped configuration, although the blank may be bent into any suitable configuration such as an S-shaped configuration or a generally square configuration. In some embodiments, the bending of board  10  occurs in-plane, meaning that the plane in which the board  10  resides is the same before and after bending. For illustration purposes only, a board placed flat on a tabletop is bent in-plane when the board can be bent into the desired shape while remaining substantially flat on the table. In some embodiments, the bending of board  10  is not limited to in-plane bending. In these embodiments, board  10  may be bent in more than one plane, such as to form a three-dimensional shape as illustrated in the non-limiting embodiment of  FIG. 5 . 
         [0018]    The repeating units  13  are designed and connected to permit such in-plane deformation or bending of the board  10 . Bridges  15  connect adjacent repeating units  13  such that the adjacent edges  18  of adjacent repeating units  13  are separated by a space  24 . In some embodiments, the adjacent edges  18  are straight, but other geometries are contemplated. Any number of repeating units  13  may be used and any number of bridges  15  connecting—and consequently any number of separating spaces  24  separating—the repeating units  13  may be provided. The number and shape of the repeating units  13 , bridges  15 , and spaces  24  may vary depending on the desired bent shape. By way only of example, the number of repeating units  13  (and consequently the number of spaces  24  between adjacent repeating units  13 ) needed to be able to bend a board  10  into a square may be less than that needed to bend a board  10  into a ring because much of the board  10  does not need to be able to bend when forming a square shape. 
         [0019]    To shape the board into the desired shape (i.e., a ring in the embodiment of  FIGS. 1 and 2 ), the board  10  is bent at and/or along bridges  15  such that adjacent repeating units  13  are brought closer to each other to narrow space  24 . Cut-outs (such as notches) may be provided proximate the bridges  15  to more precisely control and predict the location of the bends. 
         [0020]    In the embodiment of  FIGS. 1 and 2 , the board  10  is bent such that the space  24  between adjacent repeating units  13  is substantially eliminated such that the adjacent edges  18  of adjacent repeating units  13  contact each other and the ends  26 ,  28  of the board  10  meet. In this embodiment, the board  10  is self-aligning in that contact between the adjacent edges  18  of adjacent repeating units  13  limits the degree of bending and thus prevents over-bending of the board  10  beyond the desired shape. Note that in some embodiments some of the space  24  between adjacent repeating units  13  may exist after bending such that the adjacent edges  18  may not contact each other. Moreover, the ends  26 ,  28  of the board  10  may not meet in all embodiments. 
         [0021]    Once bent into its desired shape, board  10  is configured to be self-retaining such that it retains the desired shape without the help of other support structure. This may be accomplished in a variety of ways. In some embodiments, the board  10  is a metal core printed circuit board, such that the metal of the board core is plastically (and permanently) deformed and retains the board shape after bending. 
         [0022]    In other embodiments, the copper traces provided on the board (which can be metal core or otherwise) have a thickness that renders the traces strong enough to retain the entire board  10  in the desired shape after bending. In still other embodiments, mechanical retention features may be provided to retain the board. By way only of example, a tongue may be formed on one end  26  of the board  10  and a groove may be formed on the opposing end  28  of the board. Once the board  10  is bent, the tongue engages the groove to retain the board in the desired shape. 
         [0023]    In some embodiments, a flexible dielectric and a flexible solder mask is provided on the board  10  facilitate bending. 
         [0024]    In this embodiment, instead of providing a circle of LEDs on a rectangular board and removing the board material to create a ring-shaped board, a linear board may be formed directly into a ring-shaped board. This avoids the waste typically associated with customizing the shape of a PCB for a particular application. In some embodiments, a standard-sized PCB panel may be divided into multiple linear boards  10  nested in rows and temporarily connected together for handling during manufacturing and/or processing. 
         [0025]    People of skill in the art will easily appreciate that other configurations than those illustrated in the Figures may be employed. Moreover, the boards  10  disclosed herein may be used in any application and are not limited to use in lighting fixtures. 
         [0026]    The foregoing is provided for purposes of illustrating, explaining, and describing embodiments of the present invention. Further modifications and adaptations to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of the invention. Different arrangements of the components depicted in the drawings or described above, as well as components and steps not shown or described are possible. Similarly, some features and subcombinations are useful and may be employed without reference to other features and subcombinations. Embodiments of the invention have been described for illustrative and not restrictive purposes, and alternative embodiments will become apparent to readers of this patent. Accordingly, the present invention is not limited to the embodiments described above or depicted in the drawings, and various embodiments and modifications can be made without departing from the scope of the claims below.