Patent Publication Number: US-8978958-B2

Title: Method of manufacturing LED light bar

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a divisional application of patent application Ser. No. 13/209,453, filed on Aug. 15, 2011, entitled “METHOD OF MANUFACTURING LED LIGHT BAR AND MANUFACTURING EQUIPMENT THEREOF,” which is assigned to the same assignee as the present application, and which is based on and claims priority from Taiwanese Patent Application No. 100100882 filed in Taiwan on Jan. 11, 2011. The disclosures of patent application Ser. No. 13/209,453 and the Taiwanese Patent Application are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The disclosure relates to method of manufacturing semiconductor, and particularly to a method of manufacturing LED light bar and a manufacturing equipment thereof. 
     2. Description of the Related Art 
     Light emitting diodes (LEDs) have many advantages, such as high luminosity, low power consumption, compatibility with integrated circuits, easy driving, long term reliability, and environmental friendliness. These advantages have promoted wide use of the LEDs as a light source. Now, LEDs are commonly applied in lighting. 
     A conventional LED light bar includes a printed circuit board and a plurality of LEDs mounted on the printed circuit board. When manufacturing the LED light bar, the LEDs are arranged on the printed circuit board in a line with a layer of solder paste applied therebetween; then, the printed circuit board with the LEDs thereon is conveyed through a reflow oven for a reflowing process, thereby enabling the solder paste to first melt and then solidify to fix the LEDs on the printed circuit board. 
     However, in the reflowing process, the molten solder paste may cause the LEDs which are regularly arranged on the printed circuit board to float and drift. Thus, relative positions between the LEDs and the print circuit board after the reflowing process are usually become deviated from the norm, causing the light bar unable to meet customer&#39;s requirement and influencing an overall performance of the light bar. 
     What is desired, therefore, is a method of manufacturing LED light bar and a manufacturing equipment which can overcome the above-described shortcomings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic, assembled view of a manufacturing equipment for manufacturing an LED light bar according to an exemplary embodiment of the present disclosure, wherein the manufacturing equipment includes a reflow oven, a clamping device and a position sensor, and a semi-finished LED light bar is positioned in the clamping device. 
         FIG. 2  is a cross section of the semi-finished LED light bar and the clamping device of  FIG. 1 , taken along line II-II thereof. 
         FIG. 3  is an enlarged top view of a part of the semi-finished LED light bar and the clamping device and a transmitting belt of the manufacturing equipment of  FIG. 1 . 
         FIG. 4  is a schematic view showing one stage in an exemplary method of manufacturing an LED light bar according to an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the figures to describe various embodiments of the present method of manufacturing LED light bar and manufacturing equipment thereof in detail. 
     Referring to  FIG. 1 , a manufacturing equipment  50  for manufacturing an LED light bar  30  in accordance with an exemplary embodiment includes a reflow oven  20 , a clamping device  10  and a position sensor  40 . The LED light bar  30  includes a printed circuit board  34  and a plurality of LEDs  32  mounted on the printed circuit board  34  in a line. 
     The reflow oven  20  includes a hearth box  21 , a transmitting belt  22  extended through the hearth box  21  and a control unit  25 . The hearth box  21  defines an entrance  24  and an exit  26  at two opposite ends thereof. The hearth box  21  includes a low temperature area  211 , a heating area  212 , a high temperature area  213  and a cooling area  214  arranged in sequence in an interior of the hearth box  21  from the entrance  24  to the exit  26 . Each of the low temperature area  211 , the heating area  212 , the high temperature area  213  and the cooling area  214  has substantially the same width to each other. The control unit  25  can be exemplarily mounted on one side of the hearth box  21 . 
     Referring also to  FIGS. 2 and 3 , the clamping device  10  includes an elongated supporting plate  11 , two connecting plates  12  extending upward from two opposite sides of the supporting plate  11 , respectively, and two clamping arms  13  connected with top ends of the connecting plates  12 , respectively. The clamping arms  13  extend from the top ends of the connecting plates  12  toward each other. 
     The supporting plate  11  has a length substantially equal to a width of the transmitting belt  22 , and a width smaller than that of the low temperature area  211 , the heating area  212 , the high temperature area  213  and the cooling area  214  of the hearth box  21 . The connecting plates  12  extend upward from two long sides of the supporting plate  11 , respectively. A distance between the two connecting plates  12  is larger than a width of the printed circuit board  34 . The supporting plate  11  and the connecting plates  12  cooperatively define a receiving space  15  for receiving the LED light bar  30  therein. 
     Each of the connecting plates  12  includes a plurality of protruding blocks  121  extending from the top end towards the other connecting plate  12 . The protruding blocks  121  are equally spaced from each other along a lengthwise direction of the supporting plate  11 . Each of the clamping arms  13  defines a plurality of recesses  131  at a bottom side thereof corresponding to the protruding blocks  121  of a corresponding connecting plate  12 . When assembled, the clamping arms  13  are connected with the connecting plates  12  via the protruding blocks  121  engaged in the recesses  131 , respectively. 
     The clamping arms  13  are horizontally moveable with respect to the connecting plates  12  via the protruding blocks  121  slide along a corresponding recess  131  along a widthwise direction of the supporting plate  11 . The clamping arms  13  are moved between a clamping state whereby distal ends of the clamping arms  13  abutting against two opposite sides of the LEDs  32  such that positions of the LEDs  32  on the printed circuit board  34  are maintained at a required position. The clamping arms  13  are parallel to each other. The clamping device  10  connects with the control unit  25 , and is moved between the clamping state and the releasing state under control of the control unit  25 . A distance defined between the clamping arm  13  and the printed circuit board  34  of the light bar  31  is substantially equal to a half of a height of the LED  32 . 
     Referring back to  FIG. 1 , the position sensor  40  is mounted on a top surface of the clamping device  10 . The position sensor  40  can detect a position of the LED light bar  30  in real time when the LED light bar  30  is moved with the transmitting belt  22 , and output a signal which contains position message of the LED light bar  30  to the control unit  25 . In this embodiment, when the position sensor  40  detects that the LED light bar  30  has reached a first predetermined position S 1 , i.e., the entrance  24  of the reflow oven  20 , the position sensor  40  outputs a first signal to the control unit  25 , such that the control unit  25  controls the clamping device  10  to move to the clamping state. When the position sensor  40  detects that the LED light bar  30  has reached a second predetermined position S 2 , i.e., the exit  26  of the reflow oven  20 , the position sensor  40  outputs a second signal to the control unit  25 , such that the control unit  25  controls the clamping device  10  to move to the releasing state. Alternatively, the first predetermined position S 1  can be any positions before the heating area  211 , and the second predetermined position S 2  can be any positions after the cooling area  214 . 
     Referring to  FIG. 4 , a method of manufacturing the LED light bar  30  using the manufacturing equipment  50  described above is shown. The method includes following step. 
     The first step is providing the reflow oven  20  and the clamping device  10 ; the clamping device  10  is located on the transmitting belt  22  of the reflow oven  20  with the two long sides thereof perpendicular to two opposite sides of the transmitting belt  22 . 
     The second step is mounting a semi-finished LED light bar  31  in the receiving space  15  of the clamping device  10 ; the semi-finished LED light bar  31  includes the printed circuit board  34  with the LEDs  32  arranged in a line on the printed circuit board  34  and a layer of solder paste applied between the LEDs  32  and the printed circuit board  34 ; 
     The third step is starting the transmitting belt  22 , whereby the clamping device  10  and the semi-finished LED light bar  31  carried by the transmitting belt  22  move together through the reflow oven  20 . During this step, when the clamping device  10  and the semi-finished LED light bar  31  together reach the first predetermined position S 1 , the position sensor  40  outputs the first signal to the control unit  25  to thereby control the clamping device  10  to move to the clamping state. Because the first predetermined position S 1  is before the heating area  211 , when the clamping device  10  and the semi-finished LED light bar  31  together reach the heating area  211  where the solder paste is to be heated to melt, the clamping device  10  is in the clamping state such that the LEDs  32  are respectively held in position by the clamping arms  13  of the clamping device  10 . 
     When the clamping device  10  and the semi-finished LED light bar  31  together reach the second predetermined position S 2 , the position sensor  40  outputs the second signal to the control unit  25  to thereby control the clamping device  10  to move to the releasing state. The second predetermined position S 2  is after the cooling area  214 . When the clamping device  10  and the semi-finished LED light bar  31  has passed the cooling area  214 , the melted solder paste is solidified to fix the LEDs  32  on the printed circuit board  34  to form the finished LED light bar  30 . Thus, at the second predetermined position S 2 , the clamping device  10  is moved to the releasing state so that the finished LED light bar  30  can be removed from the clamping device  10 . 
     In the process of manufacturing the LED light bar  30 , the clamping device  10  is used to hold the LEDs  32  in position during the reflowing process. Thus, relative position between each of the LEDs  32  and the print circuit board  34  can be maintained during the manufacturing method of the LED light bar  30 , to thereby improve quality of the finished LED light bar  30 . 
     It is to be further understood that even though numerous characteristics and advantages have been set forth in the foregoing description of embodiments, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.