Abstract:
A method for manufacturing an integrally formed multi-layer light-emitting device is provided, in which a seat is integrally formed in such a manner that the light-emitting elements can be directly disposed in the chamber. The lens mask is used to seal the light-emitting elements in the chamber of the seat so that some packaging steps can be omitted, and the manufacturing process is simplified. The seat is made of metal having good thermal conductivity instead of plastic materials. The consumption of the package material is reduced, and the heat-dissipation efficiency is increased in the present invention.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for manufacturing a light-emitting device, and more particularly to a method for manufacturing an integrally formed multi-layer light-emitting device. 
     2. The Prior Arts 
     The light-emitting theory of LED takes advantage of the intrinsic properties of semiconductors, which is different from the theory of electric discharging, heat and light-emitting of an incandescent light tube. Because light is emitted when electric current forward flowed across the PN junction of a semiconductor, the LED is also called cold light. The LED has the features of high durability, long service life, light weight, low power consumption, and being free of toxic substances like mercury, and thereby it can be widely used in the industry of the light-emitting device, and the LEDs are often arranged in an array and often used in such as electric bulletin board or traffic sign. 
     Taiwanese Utility Model Patent No. M387375 disclosed a package structure of an array type multi-layer LED, which included a metal substrate, a package module, a lead frame, and a mask, wherein the metal substrate was disposed on the bottom of the package structure, and the package module was used for encapsulating and fixing the lead frame over the metal substrate. The LED dies were arranged in an array on the metal substrate. The lead frames were electrically connected with the LED dies. The mask covered the package module. 
     However, the conventional LED package structure includes a package module which is usually made of plastic resin. The heat-dissipation efficiency of the plastic resin is much less than that of metal. If the heat-dissipation efficiency is low, the lifetime and the light-emitting efficiency of the LED package structure will be decreased. Another problem existing in the prior art is that the metal substrate is not integrally formed with the package module, and thereby the manufacturing process is complicated. Accordingly, it is desirable to provide a light-emitting device capable of solving the problems existing in the conventional LED package structure, such as low heat-dissipation efficiency, high consumption of package material, etc. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a method for manufacturing an integrally formed multi-layer light-emitting device. The method of the present invention comprises the following steps: preparing a seat including a central main body and a plurality of heat dissipation fins, a central portion of the central main body having two through holes longitudinally formed therein; milling a bottom of the central main body to form a first chamber having an accommodating space concaved inwardly, a top of the central main body being milled to form a second chamber having an accommodating space concaved inwardly, the second chamber including a bottom and an inclined inner sidewall, the two through holes each being milled to form a step at one end near the second chamber; arranging two connection pieces in the two through holes, respectively, each connection piece including a conductive rod and a sleeve for inserting the conductive rod therein, two ends of each conductive rod being extended out of the sleeve, each conductive rod having a flange on one end near the chamber, the flange being placed on the step; arranging two fixing pieces in the two through holes, respectively, so that the two connection pieces are fixed in the seat; selectively electroplating a first reflective layer onto an area of the seat; arranging a plurality of light-emitting elements on the bottom; electrically connecting the light-emitting elements with one ends of the two connection pieces by wire-bonding with use of metal wires; and arranging a lens mask on the second chamber so that the seat is sealed by the lens mask. 
     The seat is integrally formed in such a manner that the light-emitting elements can fit in the chamber which is formed on the top of the central main body. In other words, the light-emitting elements can be directly disposed in the chamber on the top of the central main body. The seat is made of a metal having good thermal conductivity, and thereby the seat can effectively absorb the heat generated from the light emitting elements in operation, and rapidly transmit the heat to the surrounding environment. Therefore, the package module is not needed to be used in the present invention so that the consumption of the package material is reduced, and the manufacturing process is simplified. 
     According to one embodiment of the present invention, the integrally formed multi-layer light-emitting device can further includes a lens mask which is tightly engaged with the seat so that the lens mask covers and seals the top of the chamber formed on the top of the central main body. Therefore, the moisture and fine particles in air cannot enter the chamber, and thereby the light-emitting elements and the optical elements can be protected from deterioration of their properties. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be apparent to those skilled in the art by reading the following detailed description of a preferred embodiment thereof, with reference to the attached drawings, in which: 
         FIG. 1  is a flowchart showing a method for manufacturing an integrally formed multi-layer light-emitting device according to the present invention; 
         FIG. 2  is a schematic perspective view showing the seat of the integrally formed multi-layer light-emitting device according to the present invention; 
         FIG. 3   a  is a schematic perspective view showing the milling of the seat of the integrally formed multi-layer light-emitting device according to one embodiment of the present invention; 
         FIG. 3   b  is a schematic perspective view showing the milling of the seat of the integrally formed multi-layer light-emitting device according to another embodiment of the present invention; 
         FIG. 4   a  is a schematic perspective view showing a conductive rod of a connection piece according to one embodiment of the present invention; 
         FIG. 4   b  is a schematic perspective view showing the connection piece of the integrally formed multi-layer light-emitting device according to one embodiment of the present invention; 
         FIG. 5  is a schematic view showing the arrangement of the connection pieces of the integrally formed multi-layer light-emitting device according to one embodiment of the present invention; 
         FIG. 6  is a schematic view showing that two connection pieces are fixed in the seat according to one embodiment of the present invention; 
         FIG. 6   a  is a schematic view showing that a plug is inserted into each through hole according to one embodiment of the present invention; 
         FIG. 7  is a schematic view showing that a first reflective layer is selectively electroplated according to one embodiment of the present invention; 
         FIG. 8  is a schematic view showing that the light-emitting elements are arranged on the first reflective layer according to one embodiment of the present invention; 
         FIG. 9  is a schematic view showing that the light-emitting elements are arrange on the bottom by wire-bonding according to one embodiment of the present invention; 
         FIG. 10  is a schematic view showing that a lens mask is arranged on the chamber according to one embodiment of the present invention; and 
         FIG. 11  is a schematic view showing that the integrally formed multi-layer light-emitting device according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
       FIG. 1  is a flowchart showing a method for manufacturing an integrally formed multi-layer light-emitting device according to the present invention.  FIG. 2  is a schematic perspective view showing the seat of the integrally formed multi-layer light-emitting device according to the present invention. 
     In step S 10 , a seat  1  is prepared. As shown in  FIG. 2 , the seat  1  includes a central main body  11  and a plurality of heat dissipation fins  13 . The seat is formed by squeezing and injecting of a metal, and the seat is made of aluminum, copper, or carbon. The heat dissipation fins  13  are extended radially outward from the cylindrical wall of the central main body  11 . These heat dissipation fins  13  are spaced around the circumference of the central main body  11 . Two sides of the heat dissipation fins  13  are designed to have a corrugated shape. The central portion of the central main body  11  has two through holes  111  longitudinally formed therein. 
     In step S 20 , the bottom of the central main body  11  is milled by a cutter on its central portion to form a chamber  113  having an accommodating space concaved inwardly from the opening. The chamber  113  can be communicated with the two through holes  111 , as shown in  FIG. 3   a . The tops of the heat dissipation fins  13  can be milled so that a portion of the central main body  11  can be exposed and protruded, as shown in  FIG. 3   b . The shape of the outer lateral sides of the heat dissipation fins  13  can be milled into a bent arc-like shape. The reason for that is that the lower portions of the heat dissipation fins  13  receive heat slower than the upper portions of the heat dissipation fins  13  do, but the widths of the lower portions of the heat dissipation fins  13  are smaller than the widths of the upper portions of the heat dissipation fins  13 , and thereby the heat can be simultaneously dissipated to the surrounding environment through the lower portions and the upper portions of the heat dissipation fins  13  due to the shorter heat transfer path of the lower portions of the heat dissipation fins  13 , and thereby the heat dissipation efficiency is greatly increased. 
     The top of the central main body  11  can be milled by a cutter to form a chamber  115  having an accommodating space concaved inwardly from the opening, and the chamber  115  includes a bottom  115   a  and an inclined inner sidewall  115   b , as shown in  FIG. 3   b.    
     Furthermore, the two through holes  111  each can be milled to form a step  1111  at their sides near the chamber  115 . 
       FIG. 4   a  is a schematic perspective view showing a conductive rod of a connection piece according to the present invention.  FIG. 4   b  is a schematic perspective view showing the connection piece of the integrally formed multi-layer light-emitting device according to the present invention.  FIG. 5  is a schematic view showing the arrangement of the connection pieces of the integrally formed multi-layer light-emitting device according to the present invention. 
     In step S 30 , the two connection pieces  3  are respectively arranged in the two through holes  111 , as shown in  FIG. 5 . 
     The connection piece  3  includes a conductive rod  31  and a sleeve  33  for inserting the conductive rod  31  therein. The two ends of the conductive rod  31  are extended out of the sleeve  33 . The conductive rod  31  has a flange  331  on one end near the chamber  115 . The flange  331  can be placed on the step  1111  so that the two connection pieces  3  can be respectively fixed in the two through holes  111 . The sleeve  33  can be made of liquid crystalline polyester resin. 
     In step S 40 , the two fixing pieces  5  are respectively disposed in the two through holes  111  so that the two connection pieces  3  can be fixed in the seat  1 , as shown in  FIG. 6 . The connection pieces  3  can be held by the fixing pieces  5 , and the space of the two through holes  111  can be occupied by the fixing pieces  5 . A plug  6  can be inserted into the opening of each through hole  111  at its end near the chamber  115 , as shown in  FIG. 6   a , so that the connection pieces  3  can be firmly fixed, and the moisture in air can be prevented from entering the two through holes  111 . 
     In step S 50 , a first reflective layer  7  can be selectively electroplated onto an area of the seat  1 , for example, the bottom  115   a  and/or the inner sidewall  115   b , as shown in  FIG. 7 . A second reflective layer (not shown in the figures) can be electroplated onto the first reflective layer  7 . The first reflective layer  7  and the second reflective layer can be made of chromium, silver, or any other suitable metals. 
     In step S 60 , the light-emitting elements  8  are directly arranged on the first reflective layer  7  or the second reflective layer formed on the bottom  115   a , as shown in  FIG. 8 . 
     In step S 70 , the light-emitting elements  8  can be arranged in an array on the bottom  115   a , and electrically connected with one ends of the two connection pieces  3  by wire-bonding with the use of the metal wires  9 , as shown in  FIG. 9 . The light-emitting elements are, for example, a plurality of LED dies. Another ends of the two connection pieces  3  are respectively electrically connected with the negative end and the positive end of the electrical power source (not shown in the figures). Thus, the electrical power source, the two connection pieces  3 , the metal wires  9 , and the light-emitting elements  8  are electrically connected together to form a circuit. The light-emitting elements  8  can emit light when the electrical power source is turned on. The metal wires  9  can be made of gold, copper, or any other suitable metals. A connection pad (not shown in the figures) can be disposed on the top of the conductive rod  31  for wire-bonding of the light-emitting elements  8 . 
     In step S 80 , the integrally formed multi-layer light-emitting device can further includes a lens mask  10  arranged on the chamber  115  so that the seat  1  can be sealed by the lens mask  10 , and the moisture and fine particles in air can be prevented from entering the chamber  115 . 
       FIG. 11  is a schematic view showing the integrally formed multi-layer light-emitting device according to one embodiment of the present invention. Referring to  FIG. 11 , a phosphor layer  100  used for light mixing, and a silica gel protection layer  200  used for protecting the phosphor layer  100  can be sequentially formed on the light-emitting elements  8 . 
     The chamber  113  can be used for accommodating the power connector, the power supply module, and the wireless transfer module. The chamber  113  is hollow so that the seat  1  is lightweight, and the heat cannot be directly transferred to the power supply module and the wireless transfer module, and also the chamber  113  can have the heat-dissipation function. 
     Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.