Patent Publication Number: US-2019189875-A1

Title: Led frame and manufacturing method thereof

Description:
TECHNICAL FIELD 
     The present disclosure relates to an LED, in particular to an LED frame and a manufacturing method thereof. 
     BACKGROUND 
     An LED chip is too small to be electrically connected to a power supply by bonded conductive wires. Therefore, the LED chip is usually arranged on an LED frame, a circuit is disposed on the LED frame, the circuit includes electrodes for arranging the LED chip thereon, and the LED chip is thereby electrically connected to the power supply. In a conventional process, the circuit and the electrodes are made of copper, and a silver coating is usually electroplated on the electrode in order to effectively electrically connect the LED chip to the electrodes. The silver coating is well conductive and not expensive. The electrodes are arranged in pairs, and a gap between two electrodes of each pair of electrodes is quite narrow. When the LED frame is put into a soldering pot for a welding process, a silver ion migration might occur in the silver coatings of the adjacent electrodes due to a high temperature environment in the soldering pot, and therefore a short circuit is formed in the electrodes. As a result, the LED chip is damaged. 
     In views of this, in order to solve the above disadvantage, the present inventor studied related technology and provided a reasonable and effective solution in the present disclosure. 
     SUMMARY 
     The present disclosure relates to an LED, in particular to an LED frame and a manufacturing method thereof. 
     An LED frame including a ceramic substrate, a copper circuit layer, a copper electrode layer and a gold coating is provided in the present disclosure. The copper circuit layer is disposed on a surface of the ceramic substrate. The copper electrode layer covers only a part of the copper circuit layer. The reflective insulation structure covers the other parts of the ceramic substrate and the copper circuit layer, and a top of the reflective insulation structure and a top of the copper electrode layer are arranged coplanar. The gold coating entirely covers a top of the copper electrode layer, the gold coating protrudes from the top of the reflective insulation structure and a border of the gold coating coincides with a border of the copper electrode layer. 
     According to the LED frame of the present disclosure, a thickness of the copper circuit layer is less than a thickness of the copper electrode layer. A couple of electrodes are formed by the copper electrode layer, a wall surrounding the couple of electrodes is formed on the ceramic substrate and the reflective insulation structure is arranged in a region surrounded by the wall. The wall could be formed by the copper circuit layer. A plurality of circuit blocks separated from each other are defined in the copper circuit layer and at least a part of the wall and the other part of the wall are defined in respective circuit blocks. A plurality of circuit blocks separated from each other are defined in the copper circuit layer, the couple of electrodes are arranged in the respective circuit blocks, and the couple of electrodes are arranged adjacent to and separated from each other. The reflective insulation structure consists of one of silicon dioxide and titanium dioxide. 
     The LED frame of the present disclosure could further comprise a round cup surrounding the wall. 
     A manufacturing method of the LED frame is provided in the present disclosure, and the method includes following steps: providing a ceramic substrate; electroplating a copper circuit layer on a surface of the ceramic substrate; electroplating a copper electrode layer on a top of the copper circuit layer, and the copper electrode layer covers only a part of the copper circuit layer; covering an insulation glue on the ceramic substrate; solidifying the insulation glue to form a reflective insulation structure; removing a top of the reflective insulation structure to be coplanar with the top of the copper electrode layer; electroless plating a gold coating on the top of the copper electrode layer, the gold coating entirely covers the top of the copper electrode layer, the gold coating protrudes from the top of the reflective insulation structure and a border of the gold coating coincides with a border of the copper electrode layer. 
     The reflective insulation structure consists of one of silicon dioxide and titanium dioxide. According to the manufacturing method of the LED frame of the present disclosure, a thickness of the copper circuit layer is less than a thickness of the copper electrode layer. A couple of electrodes are formed by the copper electrode layer, a wall surrounding the couple of electrodes is formed on the ceramic substrate, and the insulation glue is filled in a region surrounded by the wall. The wall is a photoresist structure, and the wall is removed later. A plurality of circuit blocks separated from each other are defined in the copper circuit layer and at least a part of the wall and the other part of the wall are defined in respective circuit blocks. A plurality of circuit blocks separated from each other are defined in the copper circuit layer, the couple of electrodes are arranged in the respective circuit blocks, and the couple of electrodes are arranged adjacent to and separated from each other. 
     The manufacturing method of the LED frame of the present disclosure could further includes a step: forming a round cup surrounding the wall. 
     According to the manufacturing method of the LED frame of the present disclosure, a gold coating is electroless plated on the top of the copper electrode layer, the gold coating is chemically more stable the conventional silver coating, and an electroless plating process costs less than an electroplating process. 
    
    
     
       BRIEF DESCRIPTION OF DRAWING 
       The present disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG. 1  is a flow chart showing steps of the manufacturing method of the LED frame according to an embodiment of the present disclosure. 
         FIGS. 2 to 7  are schematic views showing the respective steps of the manufacturing method of the LED frame according to the embodiment of the present disclosure. 
         FIGS. 8 to 9  are schematic views showing various usage of the LED frame according to the embodiment of the present disclosure. 
         FIGS. 10 to 12  are schematic views showing the respective steps of the manufacturing method of the LED frame of the present disclosure for manufacturing another LED frame. 
     
    
    
     DETAILED DESCRIPTION 
     According to  FIG. 1 , a manufacturing method of an LED frame is provided in an embodiment of the present disclosure, and the method includes following steps. 
     According to  FIGS. 1 and 2 , firstly, a ceramic substrate  100  provided in step a. 
     According to  FIGS. 1 and 3 , in step b following step a, a copper circuit layer  200  is electroplated on at least a surface of the ceramic substrate  100 , a through hole  101  could be defined on the ceramic substrate  100  and for the copper circuit layer  200  is allowed to attach on an internal surface of the through hole  101  if the copper circuit layer  200  is disposed on respective surfaces of the ceramic substrate  100 , and he respective parts of the copper circuit layer  200  disposed on two surfaces of the ceramic substrate  100  are thereby electrically connected with each other. According to the present step, a wall  210  surrounding the other parts of the copper circuit layer  200  is formed by an outer part of the copper circuit layer  200 . However, scope of the present disclosure should not be limited to the embodiment, the wall  210  alternatively could be formed by a photoresist structure further arranged on the ceramic substrate  100 . Multiple circuit blocks  201   a / 201   b  separated from each other are defined in the copper circuit layer  200 , and everywhere in each circuit block  201   a / 201   b  are electrically connected with each other, and the circuit blocks  201   a / 201   b  are separated and insulated from each other. 
     According to  FIGS. 1 and 4 , in step c following step b, a copper electrode layer  300  is electroplated on top of the copper circuit layer  200 , the copper electrode layer  300  covers only a part of the copper circuit layer  200 , and a thickness of the copper circuit layer  200  is less than a thickness of the copper electrode layer  300 . A couple of electrodes  310   a / 310   b  are formed by the copper electrode layer  300 , and this couple of electrodes  310   a / 310   b  are surrounded by the aforementioned wall  210 . The respective electrodes  310   a / 310   b  of this couple of electrodes  310   a / 310   b  are defined in the respective circuit block  201   a / 201   b , and this couple of electrodes  310   a / 310   b  are arranged adjacent to and separated from each other. 
     According to  FIGS. 1 and 5 , in step d following step c, ceramic substrate  100  is covered by an insulation glue the, and the insulation glue consists one of silicon dioxide and titanium dioxide. The other parts of the copper circuit layer  200  are covered by the glue; and the insulation glue is filled in a region surrounded by the wall  210 . 
     In step e following step d, solidifying the insulation glue to form a reflective insulation structure  400 , the means of solidifying is not limited in the present disclosure, the means could be drying to solidify, heat curing, UV curing. The reflective insulation structure  400  consists of one of silicon dioxide and titanium dioxide and thereby well reflective and could be used for not only insulation between the circuit blocks  201   a / 201   b , but also reflecting lights. 
     According to  FIGS. 1 and 6 , in step f following step e, removing a top of the reflective insulation structure  400  to be coplanar with the top of the copper electrode layer  300 , the means of removing the top of the reflective insulation structure  400  is not limited in the present disclosure, the means could be planning or polishing. 
     According to  FIGS. 1 and 7 , in step g following step f, the copper electrode layer  300  is immersed into a plating solution including gold ion, and a gold coating  500  is thereby electroless plated on the top of the copper electrode layer  300  by process. Copper electrode layer  300  is exposed and completely uncovered, the gold ions in the plating solution only attach on metal surfaces, and the gold coating  500  therefore completely covers the copper electrode layer  300  and a border of the gold coating  500  coincides with a border of the copper electrode layer  300 , namely an LED frame made by the method of the present disclosure includes a feature that a region of the gold coating  500  coincides with a region of the copper electrode layer  300 . Furthermore, the top of the reflective insulation structure  400  is arranged coplanar with the top of the copper electrode layer  300 , and the gold coating  500  therefore protrudes from the top of the reflective insulation structure  400 . The wall  210  formed by the copper circuit layer  200  or the photoresist structure could be removed in this step. 
     According to  FIG. 7 , an LED chip  10  is allowed to arranged on the couple of electrodes  310   a / 310   b  of the LED frame made by the manufacturing method of the present disclosure, the LED chip  10  is arranged across between the couple of electrodes  310   a / 310   b , the LED chip  10  is driven to illuminate by different voltages loaded on the respective circuit blocks  201   a / 201   b  where the electrodes  310   a / 310   b  is located because the respective electrodes  310   a / 310   b  of the couple of electrodes  310   a / 310   b  are arranged in the respective circuit blocks  201   a / 201   b.    
     According to the present embodiment shown in  FIG. 8 , the manufacturing method of the LED frame of the present disclosure could alternatively further include a step h following the step g: forming a round cup  600  surrounding the wall  210  for containing a color fluorescent glue. 
     According to the present embodiment shown in  FIG. 7 , the LED frame made by the manufacturing method of LED frame of the present disclosure is detailly described below. The LED frame of the present disclosure includes a ceramic substrate  100 , a copper circuit layer  200 , a copper electrode layer  300  and a gold coating  500 . The copper circuit layer  200  is disposed on a surface of the ceramic substrate  100 , a wall  210  is formed by the copper circuit layer  200  and multiple circuit blocks  201   a / 201   b  separated from each other are defined in the copper circuit layer  200 . The copper electrode layer  300  covers only a part of the copper circuit layer  200  and a thickness of the copper circuit layer  200  is less than a thickness of the copper electrode layer  300 , a couple of electrodes  310   a / 310   b  are formed by the copper electrode layer  300 , the couple of electrodes  310   a / 310   b  are surrounded by the wall  210 , the respective electrodes  310   a / 310   b  of the couple of electrodes  310   a / 310   b  are arranged in respective circuit blocks  201   a / 201   b , the couple of electrodes  310   a / 310   b  are arranged adjacent to and separated from each other. The reflective insulation structure  400  is located in a region surrounded by the wall  210 , and the reflective insulation structure  400  covers the ceramic substrate and the other parts of the copper circuit layer  200 , the top of the reflective insulation structure  400  and the top of the copper electrode layer  300  are arranged coplanar. The gold coating  500  completely covers the copper electrode layer  300 , the gold coating  500  protrudes from the top of the reflective insulation structure  400  and a border of the gold coating  500  coincides with a border of the copper electrode layer  300 , the reflective insulation structure  400  consists of one of silicon dioxide and titanium dioxide and is therefore used for not only for insulation between the circuit blocks  201   a / 201   b  but also reflecting lights. 
     According to  FIG. 8 , the LED frame of the present disclosure, could alternatively further include a round cup  600  surrounding the wall  210 . The color fluorescent glue could be filled in the round cup  600  to filter specific color lights of the LED chip  10 . 
     According to the present embodiment shown in  FIGS. 7 and 8 , the LED chip  10  could be arranged across between the corresponding couple of electrodes  310   a / 310   b , the LED chip  10  is contacted with the respective gold coatings  500  on the respective corresponding electrodes  310   a / 310   b  and thereby electrically connected with the respective corresponding electrodes  310   a / 310   b . According to  FIG. 9 , the LED chip  10  could be alternatively arranged on one of the corresponding electrodes  310   a , and electrically connected with the other electrode  310   b  by a bonded wire  20 . 
     According to  FIGS. 10 to 12 , an LED frame made by the manufacturing method of LED frame of the aforementioned embodiment is provided in another embodiment of the present disclosure. The difference between the present embodiment and the aforementioned embodiment is that multiple couples of electrodes  310   a / 310   b  are formed in the copper electrode layer  300 . 
     Multiple circuit blocks  201   a / 201   b / 201   c  separated from each other are formed in the copper circuit layer  200  and at least a part of the wall  210   a  and the other parts of the wall  210   b  are formed in respective circuit blocks  201   a / 201   b , the respective electrodes  310   a / 310   b  of each couple are located in the respective circuit blocks  201   a / 201   b / 210   c . Therefore, the respective aforementioned walls  210  separated from each other are formed in the respective circuit blocks  201   a / 201   b  for electrically connecting with one of the electrodes  310   a / 310   b  to constitute a parallel circuit. Voltage sources with different electric potentials are load on the two parts of wall  210   a / 210   b  to generate a voltage difference on each couple of electrodes  310   a / 310   b.    
     According to the manufacturing method of LED frame of the present disclosure, the gold coating  500  is electroless plated on the top of the copper electrode layer  300 , the gold coating  500  is chemically more stable than a conventional electroplated silver coating and therefore able to withstand high temperature environment in welding operation, and an electroless plating operation cost much less than an electroplating operation. The LED frame made by the manufacturing method of LED frame of the present disclosure includes a feature that a region of the gold coating  500  coincides a region of the copper electrode layer  300 . 
     According to conventional operation, a mask should be arranged to cover the other parts of the copper electrode layer  300  before plating if the gold coating  500  is formed on a part of a region of the copper electrode layer  300 ; the mask should be arranged and a seed layer should be further arranged on the top of the reflective insulation structure  400  to allow gold ions to attach on the reflective insulation structure  400  if the gold coating  500  exceeds the region of the copper electrode layer  300  and covers a part of the reflective insulation structure  400 . Therefore, the conventional operation of plating gold is complex and expensive. 
     Although the present disclosure has been described with reference to the foregoing preferred embodiment, it will be understood that the disclosure is not limited to the details thereof. Various equivalent variations and modifications can still occur to those skilled in this art in view of the teachings of the present disclosure. Thus, all such variations and equivalent modifications are also embraced within the scope of the present disclosure as defined in the appended claims.