Patent Publication Number: US-2022216384-A1

Title: Electronic device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to electronic circuits, and in particular refers to an electronic device with semiconductor components. 
     2. Description of the Related Art 
     The metal electrode of the semiconductor element and the conductive circuit of the circuit board are connected through the medium (solder), and through the reflow technology, the semiconductor component is permanently fixed on the conductive circuit. In this way, the heating time is long, and it is impossible to select a specific welding position. 
     Furthermore, with the development of semiconductor technology, the side length of semiconductor components is getting smaller and smaller, and the relative metal electrode size is getting smaller and smaller. If you need to form solder on the conductive circuit or the metal electrode of the semiconductor component through the reflow technology, and then heat the solder for soldering, it can be seen that the difficulty of joining is higher. 
     SUMMARY OF THE INVENTION 
     In view of the above-mentioned deficiencies, the welding of the electronic device of the present invention does not use solder, and the heating is only directed to the part (solder joints) of the conductive circuit layer to join the metal electrodes of the semiconductor components. 
     In order to achieve the above object, the electronic device of the present invention comprises a plurality of micro-optoelectronic components and a circuit board. Each of micro-optoelectronic components comprises a semiconductor layer and metal electrodes. The metal electrodes are electrically coupled to the semiconductor layer and exposed on the surface of the semiconductor layer. The circuit board comprises a metal circuit layer and a plurality of solder joints. The solder joints are formed on the metal circuit layer, and connected to the metal electrodes of the micro-optoelectronic components. A portion of each of metal electrodes and each of solder joints of the metal circuit layer are welded to form a metal crystalline structure. The metal crystalline structure comprises the composition of the metal electrode and/or the composition of the metal circuit layer. 
     In order to achieve the above object, the electronic device of the present invention comprises a semiconductor component and a circuit board. The semiconductor component comprises a semiconductor layer and a metal electrode. The metal electrode is electrically coupled to the semiconductor layer and exposed on a surface of the semiconductor layer. The circuit board comprises a metal circuit layer and a solder joint. A portion of the metal electrode and the solder joint are welded to form a metal crystalline structure. The metal crystalline structure comprises a composition of the metal electrode and/or composition of the metal circuit layer. 
     In this way, the metal crystalline structure formed by welding can stably electrically connect the circuit board metal circuit and the semiconductor component, and can optimize the existing semiconductor welding process to improve production efficiency. 
     The detailed composition, steps, structure, characteristics, operation or use of the electronic device provided by the present invention will be described in the detailed description of the subsequent preferred embodiments. However, those with ordinary knowledge in the field of the present invention should be able to understand that these detailed descriptions and specific embodiments listed in the implementation of the present invention are only used to illustrate the present invention, and are not intended to limit the scope of the patent application of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of the electronic device of the present invention. 
         FIG. 2  is a partial enlarged view of the electronic device of  FIG. 1 . 
         FIG. 3  is a cross-sectional view along the line  3 - 3  in  FIG. 2 . 
         FIG. 4  is a cross-sectional view along the line  4 - 4  in  FIG. 2 . 
         FIG. 5  is an image of the metal electrodes of the semiconductor components of the electronic device and the metal circuit layer of the circuit board formed by welding, and taken through an electron microscope. 
         FIG. 6  is a schematic diagram of the laser beam projected to the metal circuit layer of the circuit board. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, the corresponding preferred embodiments are listed in conjunction with the drawings to illustrate the components, connections, and effects of the electronic device of the present invention. However, the composition, elements, quantity, components, size, appearance and steps of the electronic device in each of the drawings are only used to illustrate the technical features of the present invention, and not to limit the present invention. 
     As shown in  FIG. 1 , the electronic device  10  of the present invention comprises a plurality of semiconductor components  11  and a circuit board  13 . The semiconductor components  11  are also called dies. The circuit board  13  comprises a metal circuit layer  131 . The metal circuit layer  131  is exposed on the top surface of the circuit board  13 , and the exposure can be part or all of the metal circuit layer. The metal circuit layer  131  is used to transmit the power and signals required by the semiconductor components  11 . The metal circuit layer includes metal materials or alloys such as gold, silver, copper, aluminum, nickel, and stainless steel. 
     In this embodiment, semiconductor components  11  take micro-optoelectronic components as an example. The micro-optoelectronic components include one side whose length is between 1-1000 microns. In other embodiments, the semiconductor components can also be dies or combinations of other functions, such as processors, drive components, passive components, and active components. 
     As shown in  FIGS. 2-4 , the semiconductor components  11  are welded and fixed on the metal circuit layer  131  of the circuit board  13 , so that the two form an electrical connection. The circuit board  13  comprises a plurality of solder joints  132 . The solder joints  132  are formed on the metal circuit layer  131 , and connected to the metal electrodes of the semiconductor components  11 . 
     In this embodiment, the semiconductor components  11  comprise an N-type semiconductor layer  111 , a P-type semiconductor layer  112 , a light-emitting layer  113 , a conductive layer  114 , an insulating layer  115 , an N-metal electrode  116 , and a P-metal electrode  117 . The structure from top to bottom is N-type semiconductor layer  111 , light-emitting layer  113  and P-type semiconductor layer  112 . The materials of the N-metal electrode  116  and the P-metal electrode  117  are, for example, metal materials or alloys such as gold, copper, silver, and aluminum. 
     The N-metal electrode  116  comprises a vertical structure  1161  and a horizontal structure  1163  extending from the vertical structure  1161  (the double-dot chain line in  FIG. 2  represents the range). The vertical structure  1163  passes through the P-type semiconductor layer  112  and the light-emitting layer  113 , and is electrically connected to the N-type semiconductor layer  111 . The horizontal structure  1163  is exposed at the bottom of the semiconductor component  11 . The conductive layer  114  connects to the P-type semiconductor layer  112 . The insulating layer  115  is located between the N-metal electrode  116 , the P-type semiconductor layer  112 , the light-emitting layer  113 , and the conductive layer  114  to avoid the N-metal electrode  116  and the P-metal electrode  117  short. The P-metal electrode  117  comprises a vertical structure  1171  and a horizontal structure  1173  extending from the vertical structure  1171  (the double-dot chain line in  FIG. 2  indicates the range). The vertical structure  1171  of the P-metal electrode  117  passes through the conductive layer  114  to connect to the P-type semiconductor layer  112 . The horizontal structure  1173  of the P-metal electrode  117  is exposed at the bottom of the semiconductor component  11 . The vertical structures  1161  and  1171  can be formed by via technology. 
     The N-type semiconductor layer  116  and the P-type semiconductor layer  117  provide electrons and holes respectively. The light-emitting layer  113  is used to convert electricity into light, and the material of the light-emitting layer  113  can change the color of light. 
     In other embodiments, the structure (layer) combination of other functional semiconductor components  11  and the number of metal electrodes will be different. Therefore, the number of semiconductor layers and metal electrodes can be at least one each, and more can be three or more. In addition, the structure of the N-metal electrode  161  and the P-metal electrode  171  can also be different. 
     The metal circuit layer  131  of the circuit board  13  comprises a plurality of marks  133 , and the N-metal electrodes  161  and the P-metal electrodes  171  of the semiconductor components  11  are located between the marks  133 . The marks  133  are used to assist the positioning of the semiconductor components. The marks  133  of this embodiment are semicircular gaps, and the shape of the gaps in other embodiments may be other geometric shapes or adopt other forms, such as patterns, colors, or words. 
     The welding is to heat the solder joints  132  to form a plurality of molten pools between the solder joints  132  and a portion of each of the metal electrodes  161  and  171  of the semiconductor components  11 , as shown in the elliptical area of  FIG. 4 , and after cooling, multiple metal crystalline structures are formed. 
     The molten pools are to heat the metal circuit layer  131  or the metal electrodes  161 ,  171  to its melting point, so that the heated part changes from solid to liquid or paste, and the liquid or paste is cooled to form metal crystalline structures and the metal circuit layer  131  or the metal electrodes  161 ,  171  are connected together, as shown in  FIG. 5 . 
     In this embodiment, the heating is through the laser beam, so that the laser beam interacts with the metal material of the solder joints  132  to melt. The solder joints  132  are part of the metal circuit layer  131  and are the same material as the metal circuit layer  131 . 
     The heating temperature is related to the material or composition of the metal circuit layer  131  and the metal electrode  116 ,  117 . For example, conductive metals such as nickel, gold, and copper above 1000 degrees Celsius, and conductive metals such as silver and aluminum at 500 degrees to 1000 degrees Celsius. Therefore, the heating temperature of the present invention is usually greater than 430 degrees Celsius. The range and size of the solder joints  132  are related to the focusing range of the laser beam. 
     In this embodiment, the hollow circles represent the positions of the vertical structures  1161  and  1171 , and the solid circles represent the welding positions, that is, the overlapped and connected positions of the portions  1165  of the N-metal electrodes  116 , the portions  1175  of the P-metal electrodes  117 , and the solder joints  132 . 
     Since the position structures that the horizontal structures  1163  and  1173  are directly opposite or connected to the respective vertical structures  1161  and  1171  are not suitable for welding. Therefore, the welding positions are selected to deviate from the vertical structures  1161  and  1171 . The deviation refers to the vertical projection of the vertical structures  1161  and  1171  outside the range of the horizontal structures  1163  and  1173 . 
     Take the uppermost semiconductor component  11  in  FIG. 2  as an example of the deviation method. The horizontal structure  1163  of the N-metal electrode  116  is rectangular, and the vertical structure  1161  is located at the top in  FIG. 2 . Therefore, the welding position (i.e., the portion  1165  of the N-metal electrode  116 ) can be selected at the position below the vertical structure. Similarly, since the horizontal structure  1173  of the P-metal electrode  117  is rectangular, and the vertical structure  1171  is at the bottom of  FIG. 2 , the welding position (that is, the portion  1175  of the P-metal electrode  117 ) can be selected as the position above the vertical structure. 
     In other embodiments, since the range of the horizontal structures is larger than the vertical structures, the horizontal structures may be other shapes, such as a circle or an ellipse, the welding positions can still choose to deviate from the vertical structures. 
     As shown in  FIG. 5 , the figure is an image of the welding of portions of the metal electrodes of the semiconductor components and the solder joints, and taken through an electron microscope. The metal crystalline structure includes bubble or air holes  1321 , which are holes left by the molten pool gas during the bonding process of the solder joints  132  and the metal electrodes  116  and  117  of the semiconductor component  11 . In addition, the solder joints  132  and the portions  1165  and  1175  of the metal electrodes  116  and  117  are not damaged by laser processing to ensure the structural stability of the semiconductor component  11 . In other embodiments, air holes may not exist. 
     As shown in  FIG. 6 , the circuit board  13  comprises a transparent substrate  135 , and the metal circuit layer  131  is formed on the top surface  1351  of the transparent substrate  135 . The heating of the welding involves projecting the laser beam  15  from the bottom surface of the transparent substrate  135  and focusing on the solder joints  132 , so that the solder joints  132  are melted with the laser beam  15  in a short time to form a molten pool (the black column area in the drawing). The top surface of the solder joint  132  is in contact with the portion of the metal electrode of the semiconductor component  11 , and then after the laser beam  15  stops projecting, the liquid or paste metal components in the molten pool range are cooled to achieve efficient welding in a short time. It can be seen that the melting point temperature of the metal circuit layer  131  can be lower than or the same as the melting point temperature of the metal electrode. 
     The molten pools penetrate the top surface and bottom surface of the metal circuit layer  131 , and located at the solder joints  132 , and comprise portions of the metal electrodes. The top surface of metal circuit layer  131  is contacted with the metal electrode  116 ,  117 . Therefore, the composition of the molten pools comprises the composition of the metal circuit layer  131  and the metal electrodes. However, in other embodiments, the molten pools may not penetrate the metal circuit layer  131 , but is formed between the top surface of the metal circuit layer  131  and the metal electrodes. In addition, molten pools can also be formed on the edges of the metal circuit layer  131  and the metal electrodes that are in contact to form metal crystalline structures. 
     Since metal can efficiently transfer heat, in other embodiments, although the laser beam heats the solder joints  132 , the heat is transferred to the portions  1165  of the N-metal electrodes  116  and the portions  1175  of the P-metal electrodes  117  that are in contact with the solder joints  132 . Therefore, when the melting point of the composition of the N-metal electrodes  116  and the P-metal electrodes  117  is lower than the melting point of the composition of the metal circuit layer  131 , during the heating process, the portions  1165  of the N-metal electrodes  116  and the portions  1175  of the P-metal electrodes  117  that contact the metal circuit layer  131  first reach the melting point of the material through heat transfer, the portions  1165  of the N-metal electrodes  116  and the portions  1175  of the P-metal electrodes  117  form molten pools, and are welded to the solder joints  132  after cooling. 
     Through the laser welding operation, the local metal can be heated to the melting point of the metal faster than the reflow technology, so as to effectively weld the two metal materials (the solder joints of the metal circuit layer and the metal electrodes of the semiconductor component) together to avoid heat accumulation and damage the structure of the semiconductor components. 
     In other embodiments, the laser beam can also be projected from the side of the top surface of the circuit board to the metal circuit layer. Therefore, the circuit board is not limited to comprising the transparent substrate. 
     In this way, the electronic device of the present invention can gradually complete the fusion of multiple semiconductor components with metal electrodes on the metal circuit layer through the projection of a laser beam, so as to improve the process efficiency of a large number of semiconductor components. 
     Because the electronic device of the present invention can effectively combine semiconductor components and circuit boards, and does not require the use of solder or media, the process of soldering and reflow operations can be omitted to improve efficiency. 
     Furthermore, the welding of the present invention can selectively heat the solder joints of the metal circuit layer without heating the whole or the metal electrodes of the semiconductor components. Therefore, the structure or function of the semiconductor components is less likely to be damaged by heat accumulation. 
     Finally, it is emphasized again that the constituent elements disclosed in the previously disclosed embodiments of the present invention are only examples and are not used to limit the scope of the present invention. The substitution or change of other equivalent elements should also be covered by the scope of the patent application of the present invention.