Abstract:
An electronic package structure is provided which comprises a metal core PCB, an energy storage device and at least one electronic component. The at least one electronic component is disposed between the metal core PCB and the energy storage device. The metal core PCB defines at least a through hole. A thermal passage is disposed in the through hole. An insulating layer is disposed in the through hole and located between the metal layer of the metal core PCB and the thermal passage to prevent the electric coupling between the thermal passage and the metal layer. The energy storage device comprises at least a connecting pin in thermal contact with the thermal passage.

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The invention relates to a metal core printed circuit board and an electronic package structure, particularly to a metal core printed circuit board and an electronic package structure having better heat dissipation. 
     (b) Description of the Related Art 
       FIG. 1  shows a DC-to-DC converter package according to the prior art. As shown in  FIG. 1 , the DC-to-DC converter package is disclosed in U.S. Pat. No. 6,212,086. DC-to-DC converter package  100  comprises circuit board  120 , copper plate  110  and a plurality of electronic components. Copper plate  110  is clad to the bottom surface of circuit board  120  and thus allows heat to be approximately equally distributed over the bottom of the package. The electronic components include main transformer  130 , output inductor  140 , synchronous rectifier  150 , output capacitor  160  and input capacitor  170 , and are disposed on circuit board  120  so that the electronic components may be coupled to each other through the circuit layout inside circuit board  120 . One stand-alone output connector is disposed on the right-hand side of circuit board  120  and coupled to circuit board  120  through a flexible printed circuit board. The disadvantage of this prior art is that circuit board  120  is not a good heat sink and cannot efficiently dissipate heat generated by electronic components  130 ,  140 ,  150 ,  160  and  170  thereon to copper plate  110 . The use of circuit board  120  would make it easy to allocate the circuit layout but make it difficult to dissipate heat. On the contrary, the use of copper plate  110  would make it difficult to allocate the circuit layout but make it easy to dissipate heat. It is urged by those who are skilled in the art to develop one substrate having both advantages of easy circuit allocation and heat dissipation. 
     BRIEF SUMMARY OF THE INVENTION 
     One object of the invention is to provide an electronic package structure having better heat dissipation than the prior technology. An electronic package structure according to the invention is suitable to circuits and electronic components having small volume and high density. In one embodiment, one object of the invention is to provide a metal core printed circuit board suitable to be used in an electronic package structure. 
     One embodiment of the invention provides an electronic package structure, comprising a metal core PCB, an energy storage device and at least one electronic component. The metal core PCB comprises a first surface and a second surface and defines at least a through hole. The first surface is opposite to the second surface and the through hole extends from the first surface to the second surface. The metal core PCB comprises a metal layer, a circuit layer, at least one thermal passage and at least one insulating layer. The circuit layer is disposed on the metal layer and comprises a circuit layout. The thermal passage is disposed in the through hole. The insulating layer is disposed in the through hole and disposed between the thermal passage and the metal layer to prevent the thermal passage and the metal layer from being electrically coupled. The energy storage device comprises at least a connecting pin, being in thermal contact with the thermal passage and extending along a direction away from the energy storage device so that a storage space is formed between the energy storage device and the metal core PCB. At least one of the electronic components is coupled to the circuit layout and disposed in the storage space. 
     Furthermore, one embodiment of the invention provides a metal core printed circuit board, comprising a first surface and a second surface and defining at least one through hole. The first surface is opposite to the second surface and the through hole extends from the first surface to the second surface. The metal core PCB comprises a metal layer, a circuit layer, at least one thermal passage and at least one insulating layer. The circuit layer is disposed on the metal layer and comprises a circuit layout. The thermal passage is disposed in the through hole and the insulating layer is disposed in the through hole and disposed between the thermal passage and the metal layer to prevent the thermal passage and the metal layer from being electrically coupled. When an electronic device is electrically coupled to the thermal passage, the electronic device and the metal layer are electrically insulated from each other. 
     In one embodiment, the at least one through hole, the at least one insulating layer and the at least one thermal passage each are plural. The electronic components comprise a first electronic component and a second electronic component. Heat generated by the first electronic component is larger than that by the second electronic component and the first electronic component is in thermal contact with one of the thermal passages. 
     In one embodiment, the insulating layer can comprise a plastic sheath or insulating film and the thermal passage can comprise a rivet or thermally conductive material. Preferably, the thermal passage is made of metal. In one embodiment, the electronic package structure can be a DC-to-DC converter package. 
     As described in the above, a storage space is formed between the energy storage device and the metal core PCB, and a plurality of electronic components can be disposed on the metal core PCB and in the storage space so that a stacking structure is formed to have the space be effectively utilized and a high density integrated power device can be formed. Besides, since the metal core PCB is formed with the insulating layer and the thermal passage, the connecting pin of the energy storage device can be coupled to the thermal passage and the heat generated by the energy storage device can be conducted to the second side of the metal core PCB through the connecting pin and the thermal passage. When the thermal passage is made of metal, the thermal passage can be used to conduct electricity and to electrically connect to an external substrate (not shown in the figure). 
     In one embodiment, in the metal core PCB, a thermal passage and an insulating layer are in the through hole and the thermal passage is electrically insulated from the metal layer of the metal core PCB. Thus, when an electronic component is electrically coupled to the thermal passage, the electronic component is electrically insulated from the metal layer of the metal core PCB without being short circuited so that an external circuit substrate can be electrically coupled. 
     Other objects and advantages of the invention can be better understood from the technical characteristics disclosed by the invention. In order to clarify the above mentioned and other objects and advantages of the invention, examples accompanying with figures are provided and described in details in the following. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic diagram illustrating a DC-to-DC converter package according to the prior art. 
         FIG. 2  shows a schematic diagram illustrating an electronic package structure according to one embodiment of the invention. 
         FIG. 3  shows a schematic diagram illustrating an electronic package structure according to one embodiment of the invention. 
         FIG. 4  shows a schematic diagram illustrating an electronic package structure according to one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 2  shows a schematic diagram illustrating an electronic package structure according to one embodiment of the invention. In one embodiment of the invention, electronic package structure  200  can be a DC-to-DC converter package, that is, a power supply module package structure. As shown in  FIG. 2 , electronic package structure  200  includes a metal core printed circuit board (MCPCB)  210 , a plurality of electronic components  220 , a plurality of conducting wires  230  and an energy storage device  240 . The electronic components  220  are disposed on a first side of MCPCB  210  and coupled to a circuit layout (not shown) in MCPCB  210 . In this embodiment, the electronic components  220  include a first electronic component  221  and a second electronic component  222 . Heat generated by the first electronic component  221  is larger than that by the second electronic component  222 . Specifically, the first electronic component  221  can be a power element, that is, an electronic component generating a large amount of heat, such as chip, integrated component, metal-oxide-semiconductor field-effect transistor (MOSFET), insulated-gate bipolar transistor (IGBT), diode, main transformer and synchronous rectifier. The second electronic component  222  can be a passive component or microelectronic component, that is, an electronic component generating a small amount of heat. 
     MCPCB  210  includes a metal layer  211  and a circuit layer  212 . The circuit layer  212  includes at least one conducting wiring layer  212   a  and an insulating layer  212   b  to form the circuit layout  212   c . The metal layer  211  is disposed on the second side of the MCPCB  210  and the second side is opposite to the first side. In one embodiment, in order to increase the effect of heat dissipation, the metal layer  211  is disposed over the entire bottom surface of the circuit layer  212 . 
     In this embodiment, the MCPCB  210  defines at least one through hole  216 . The through hole  216  penetrates the bottom surface  21   b  and the top surface  21   a  of MCPCB  210 . An insulating layer  213  and a thermal passage  214  are disposed in the through hole  216 , and the insulating layer  213  is disposed on a wall defining the through hole  216  and defines an opening. The thermal passage  214  is disposed in the opening so that the insulating layer  213  is disposed between the thermal passage  214  and the metal layer  211 . In one embodiment, the material of the thermal passage  214  is metal. Since the insulating layer  213  is disposed between the thermal passage  214  and the metal layer  211  of the MCPCB  210 , there is no current loop between the thermal passage  214  and the metal layer  211 . 
     The energy storage device  240  may be an inductor device, more specifically, a choke device including a choke  242  and a plurality of connecting pins  241 . The connecting pins  241  are disposed at two sides of the choke  242 , coupled to the choke  242  and extend along a direction away from the bottom surface of the choke  242 . The energy storage device  240  is disposed on the first side of the MCPCB  210  and one connecting pin  241  is connected to one thermal passage  214 . A space is defined between the choke  242  and the MCPCB  210  to accommodate electronic components  220 . By such design, the energy storage device  240  and the electronic components  220  are not disposed on a flat surface but form a stacking structure to use space effectively. Besides, heat generated by the choke  242  can be dissipated to the second side of the MCPCB  210  through the connecting pin  241  and the thermal passage  214 . Since the thermal passage  214  is made of metal, the choke  242  can be electrically coupled to the external circuit board  900  through the connecting pins  241  and the thermal passage  214 . The external circuit board  900  is disposed on the second side of the MCPCB  210  and the choke  242  is disposed on the first side of the MCPCB  210 . 
     Besides, since the first electronic component  221  generated a larger amount of heat, a pin  21   c  of the first electronic component  221  is in thermal contact with the thermal passage  214  and heat generated by the first electronic component  221  can be conducted to the second side of the MCPCB  210  through the pin  21   c  and the thermal passage  214 . Since the thermal passage  214  is made of metal, the first electronic component  221  may be electrically coupled to the external circuit board  900  through the thermal passage  214 . 
     In the embodiment of  FIG. 2 , the insulating layer  213  can be a plastic sheath. The plastic sheath can be, for example, an “H”-shaped plastic expansion bolt  13   a  or sleeve expansion bolt. The thermal passage  214  may be a rivet  14   a . Processing the insulating layer  213  and the thermal passage  214  can include the following steps. Step S 02 : at least one through hole  216  is formed on the MCPCB  210  in advance. Step S 04 : the “H”-shaped plastic expansion bolt  13   a  is plugged in the through hole  216 . Step S 06 : finally the metallic rivet  14   a  is nailed into the “H”-shaped plastic expansion bolt  13   a . In one embodiment, the firstly rivet  14  is nailed into the “H”-shaped plastic expansion bolt  13   a  and then the rivet  14  and the “H”-shaped plastic expansion bolt  13   a  together are plugged into the through hole  216 . 
       FIG. 3  shows a schematic diagram illustrating an electronic package structure according to one embodiment of the invention. The electronic package structure  200   a  of the embodiment of  FIG. 3  is similar to the electronic package structure  200  of the embodiment of  FIG. 2 . Thus, the same element is represented by the same symbol and its details are also not given hereinafter. As shown in  FIG. 3 , processing the insulating layer  213  and the thermal passage  214  can include the following steps. Step S 22 : at least one through hole  216  is formed on the MCPCB  210  in advance. Step S 24 : a polymeric material is filled into the through hole  216 . Step S 26 : an opening is formed in the polymeric material to have the area of the opening be smaller than that of the through hole  216  so as to form an insulating film  13   b . Step S 28 : finally thermally conductive material  14   b  is filled into the opening. In one embodiment, the thermally conductive material  14   b  made of metallic material can be formed by electroplating. In one embodiment, the thermally conductive material  14   b  can be formed by filling metallic conductive paste into the opening and then carrying out annealing. 
     As described in the above, after the insulating layer  213  and the thermal passage  214  are formed on the MCPCB  210 , each electronic component  220  is formed on the surface of the first side of the MCPCB  210  (step  32 ). Finally, the energy storage device  240  is disposed on the first side of the MCPCB  210  to have one connecting pin  241  be connected to one rivet  14   a  or one thermally conductive material  14   b  (thermal passage  214 ). In addition, a space is defined between the choke  242  and the MCPCB  210  to accommodate the electronic components  220 . Thus, the electronic package structure  200  or the electronic package structure  200   a  is formed. 
     In the electronic package structure  200  of the embodiment of  FIG. 2 , the insulating layer  213  and the thermal passage  214  are implemented by the plastic expansion bolt  13   a  and the rivet  14   a , respectively. Additional processes, such as repeatedly excavating holes and filling materials, are not needed and thus production is simple and cost is low. On the other hand, in the electronic package structure  200   a  of the embodiment of  FIG. 3 , the insulating layer  213  and the thermal passage  214  can be formed into various shapes and sizes and are suitable to products having complex circuits. Besides, in one embodiment, the insulating layer  213  and the thermal passage  214  are implemented by the insulating film  13   b  and the rivet  14   a , respectively. In another embodiment, the insulating layer  213  and the thermal passage  214  are implemented by a plastic sheath ( 13   a ) and the thermally conductive material  14   b , respectively. 
     As described in the above, a storage space is formed between the energy storage device  240  and the MCPCB  210 . A plurality of electronic components  220  are disposed on the MCPCB  210  and in the storage space to from a stacking structure which uses space effectively so that a high density integrated power device can be formed. Since the MCPCB  210  is formed with the insulating layer  213  and the thermal passage  214 , the connecting pin  241  of the energy storage device  240  can be coupled to the thermal passage  214  and heat generated by the energy storage device  240  can be conducted to the second side of the MCPCB  210  through the connecting pin  241  and the thermal passage  214 . When the thermal passage  214  is made of metal, the thermal passage  214  is electrically conductive and the energy storage device  240  may be in electrically connection with an external circuit board through the thermal passage  214 . 
     Besides, in the invention, it is not limited to form a storage space between the energy storage device  240  and the MCPCB  210  so as to from the electronic package structure  200  having a stacking structure.  FIG. 4  shows a schematic diagram illustrating an electronic package structure according to one embodiment of the invention. The electronic package structure  200   b  of the embodiment of  FIG. 4  is similar to the electronic package structure  200  of the embodiment of  FIG. 2 . Thus, the same element is represented by the same symbol and its details are also not given hereinafter. As shown in  FIG. 4 , the choke  242  and the electronic components  220  are disposed on the surface of the MCPCB  210  and are not formed into a stacking structure. Heat generated by the choke  242  is conducted to the second side of the MCPCB  210  through the connecting pin  241  and the thermal passage  214 . 
     Although the present invention has been fully described by the above embodiments, the embodiments should not constitute the limitation of the scope of the invention. Various modifications or changes can be made by those who are skilled in the art without deviating from the spirit of the invention. Any embodiment or claim of the present invention does not need to reach all the disclosed objects, advantages, and uniqueness of the invention. Besides, the abstract and the title are only used for assisting the search of the patent documentation and should not be construed as any limitation on the implementation range of the invention.