Patent Publication Number: US-2023132928-A1

Title: Electronic device and circuit board module thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This non-provisional application claims priority under 35 U.S.C. § 119(a) to Patent Application No. 110141044 filed in Taiwan, R.O.C. on Nov. 3, 2021, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     Technical Field 
     The instant disclosure relates to an electronic component, in particular, to a circuit board module and an electronic device with the circuit board module. 
     Related Art 
     Electronic components are provided on the circuit boards of various electronic devices. For example, regarding a camera device, a light source, e.g., light-emitting diode (LED), is usually applied to be served as the supplementary lighting. Therefore, when the camera device performs image capturing procedures, clearer images can be obtained owing to the illumination of the light source. Moreover, with the application of the light source, images can be captured with sufficient brightness at night or in low light conditions. 
     SUMMARY 
     However, during the operation, the temperature of electronic components with high power (such as the aforementioned light source) generally greatly increases. Moreover, the more the power of the electronic component is, the more the heat generated by the electronic component is. Therefore, under a long-term use, the high temperature of the electronic component not only easily affects the operation and service life of the electronic component but also affects the operations of other peripheral components. Especially, the high temperature of the electronic component may cause components which are not heat-resistant to be damaged, failed, or even spontaneously ignited. 
     In view of this, in one embodiment, a circuit board module is provided. The circuit board module comprises a circuit board, a metal core printed circuit board, and a heating element. The circuit board comprises a substrate, and a surface of the substrate has an assembling region. The metal core printed circuit board is disposed on the assembling region. The metal core printed circuit board comprises a first circuit layer and a second circuit layer. The first circuit layer and the second circuit layer are electrically connected to each other. The second circuit layer is electrically connected to the circuit board, and a thermal conductivity of the metal core printed circuit board is greater than a thermal conductivity of the substrate. The heating element is disposed on the metal core printed circuit board and electrically connected to the first circuit layer. 
     In another embodiment, an electronic device is provided. The electronic device comprises a housing and the aforementioned circuit board module, and the circuit board module is disposed in the housing. 
     Based on the above, in the circuit board module according to one or some embodiments of the instant disclosure, the heating element is disposed on the metal core printed circuit board. Therefore, the heat generated by the heating element upon the operation of the heating element can be quickly transmitted to the substrate of the circuit board through the metal core printed circuit board, so that the temperature of the heating element can be prevented from getting too high. Moreover, according to one or some embodiments of the instant disclosure, the metal core printed circuit board is just arranged on portions of the substrate. Therefore, in these embodiments, the cost for the circuit board module can be greatly reduced, as compared with embodiments having the metal core printed circuit board on the entire substrate. Furthermore, according one or some embodiments of the instant disclosure, the thermal conductivity of the substrate is less than the thermal conductivity of the metal core printed circuit board. Therefore, the heat generated by the heating element can be prevented from affecting operations of other components on the substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will become more fully understood from the detailed description given herein below for illustration only, and thus not limitative of the disclosure, wherein: 
         FIG.  1    illustrates a perspective view of an electronic device according to an exemplary embodiment of the instant disclosure; 
         FIG.  2    illustrates an exploded view of the electronic device of the exemplary embodiment; 
         FIG.  3    illustrates an exploded view of a circuit board module according to an exemplary embodiment of the instant disclosure; 
         FIG.  4    illustrates a cross-sectional view of the circuit board module of the exemplary embodiment; 
         FIG.  5    illustrates a plan view of the circuit board module of the exemplary embodiment; 
         FIG.  6    illustrates a plan view of the electronic device of the exemplary embodiment; and 
         FIG.  7    illustrates an enlarged partial cross-sectional view of the electronic device shown in  FIG.  6   . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments are provided for facilitating the descriptions of the instant disclosure. However, the embodiments are provided as examples for illustrative purpose, but not a limitation to the instant disclosure. In all the figures, the same reference numbers refer to identical or similar elements. 
       FIG.  1    illustrates a perspective view of an electronic device  1  according to an exemplary embodiment of the instant disclosure.  FIG.  2    illustrates an exploded view of the electronic device  1  of the exemplary embodiment. As shown in  FIG.  1    and  FIG.  2   , in this embodiment, the electronic device  1  comprises a housing  10  and a circuit board module  20 , and the circuit board module  20  is disposed in the housing  10 . For example, the circuit board module  20  may be fixed inside the housing  10  through locking, adhering or engaging. In some embodiments, the electronic device  1  may be a doorbell device (e.g., a wired doorbell, a wireless doorbell, or a smart doorbell). The electronic device  1  is adapted to be assembled at the entrance or exit of a residence, an office, or a commercial building, and the electronic device  1  can be served as a communication media between the indoor space and the outdoor space. Alternatively, in some embodiments, the electronic device  1  may be an IP camera, a network camera, a closed-circuit television (CCTV), or an analog surveillance camera, and the electronic device  1  is adapted to be assembled at different places (e.g., a kinder garden, an office, or a store), thus the electronic device  1  can perform the security surveillance function or record personnel activities. However, it is understood that the foregoing embodiments are provided for illustrative purposes, but not limitations of the instant disclosure; in some embodiments, the electronic device  1  may be an appliance assembled with the circuit board module  20 . 
       FIG.  3    illustrates an exploded view of a circuit board module  20  according to an exemplary embodiment of the instant disclosure. As shown in  FIG.  2    and  FIG.  3   , the circuit board module  20  comprises a circuit board  21 , at least one metal core printed circuit board  25 , and at least one heating element  26 . The circuit board  21  comprises a substrate  211 , and a surface of the substrate  211  has an assembling region  212  and a circuit region  213 . Specifically, in some embodiments, the assembling region  212  and the circuit region  213  are different portions of the surface of the substrate  211 . The assembling region  212  is for assembling with the metal core printed circuit board  25  and the heating element  26 , and the circuit region  213  is for assembling with other electronic components (e.g., a conductive wire, a microprocessor, a microphone, a resistor, and a capacitor). 
     In some embodiments, the shape of the circuit board  21  may be configured according to actual requirements. For example, as shown in  FIG.  2    and  FIG.  3   , in this embodiment, an image capturing module  15  is disposed in the housing  10  of the electronic device  1 . For example, the image capturing module  15  may be a charge-coupled device (CCD), a complementary metal-oxide semiconductor (CMOS), a CMOS active pixel sensor, or the like. The substrate  211  of the circuit board  21  of the circuit board module  20  may be an annular-shaped board (for example, in this embodiment, the substrate  211  is of a circular ring shape, but may also be rectangular ring shaped, elliptical ring shaped, or other irregular ring shaped), and the substrate  211  formed in an annular shape surrounds the image capturing module  15 . However, embodiments are not limited thereto, and the substrate  211  may be configured as other non-annular structures. In some embodiments, the circuit board  21  may comprise several substrates  211 , and the substrates  211  are spaced apart from each other and arranged around the periphery of the image capturing module  15 . Moreover, the substrates  211  may be individually arranged or electrically connected to each other. 
     Moreover, as shown in  FIG.  2   , in this embodiment, the electronic device  1  may further comprise a light-permissible shield  16  to cover the image capturing module  15 , so that the image capturing module  15  can be protected by the light-permissible shield  16 . For example, the light-permissible shield  16  may be made of a transparent material, and the transparent material for example may be polycarbonate (PC), polymethyl methacrylate (PMMA), or glass materials. Therefore, an external light can pass through the light-permissible shield  16  to be transmitted to the image capturing module  15 , so that the image capturing module  15  can perform image sensing to obtain images properly. 
     In some embodiments, the number of the assembling region  212 , the circuit region  213 , the metal core printed circuit board  25 , and the heating element  26  can be adjusted according to actual requirements. For example, as shown in  FIG.  5   ,  FIG.  5    illustrates a plan view of the circuit board module  20  of the exemplary embodiment. In this embodiment, the number of the assembling region  212 , the metal core printed circuit board  25 , and the heating element  26  are plural (in this embodiment, the number is six, but embodiments are not limited thereto). The assembling regions  212  are at different locations of the surface of the substrate  211  and are annularly arranged around the periphery of the image capturing module  15 , and the metal core printed circuit boards  25  and the heating elements  26  are assembled on the assembling regions  212  respectively. Moreover, in this embodiment, the number of the circuit region  213  is also plural, and each of the circuit regions  213  is between the assembling regions  212 . However, it is understood that the foregoing embodiments are provided for illustrative purposes, but not limitations of the instant disclosure. In some embodiments, the number of the assembling region  212 , the circuit region  213 , the metal core printed circuit board  25 , and the heating element  26  may be one, depending on the actual product requirements. 
       FIG.  4    illustrates a cross-sectional view of the circuit board module  20  of the exemplary embodiment. As shown in  FIG.  3    and  FIG.  4   , taking one assembly of the metal core printed circuit board  25  and the heating element  26  as an example, the metal core printed circuit board  25  is stacked on the assembling region  212  of the substrate  211 , and the metal core printed circuit board  25  comprises a first circuit layer  251 , a first spacing layer  254 , a metal thermal conductive layer  252 , a second spacing layer  255 , and a second circuit layer  253 . The first circuit layer  251 , the first spacing layer  254 , the metal thermal conductive layer  252 , the second spacing layer  255 , and the second circuit layer  253  are stacked one another. The metal thermal conductive layer  252  is between the first circuit layer  251  and the second circuit layer  253 , the first spacing layer  254  is sandwiched between the first circuit layer  251  and the metal thermal conductive layer  252 , and the second spacing layer  255  is sandwiched between the metal thermal conductive layer  252  and the second circuit layer  253 . In this embodiment, the first circuit layer  251  is the top layer of the metal core printed circuit board  25 , the second circuit layer  253  is the bottom layer of the metal core printed circuit board  25 , and the second circuit layer  253  is nearer to the substrate  211  of the circuit board  21  as compared to the first circuit layer  251 . In other words, in this embodiment, the distance between the second circuit layer  253  of the metal core printed circuit board  25  and the substrate  211  of the circuit board  21  is less than the distance between the first circuit layer  251  of the metal core printed circuit board  25  and the substrate  211  of the circuit board  21 . 
     As shown in  FIG.  3    and  FIG.  4   , the heating element  26  is disposed on the metal core printed circuit board  25  and electrically connected to the first circuit layer  251 , the first circuit layer  251  and the second circuit layer  253  of the metal core printed circuit board  25  are electrically connected to each other, and the second circuit layer  253  is electrically connected to the circuit board  21 . Therefore, the heating element  26  is electrically connected to the circuit board  21  indirectly through the first circuit layer  251  and the second circuit layer  253 . 
     In some embodiments, the heating element  26  may be a light emitting element; for example, the light emitting element may be a light-emitting diode (LED), an infrared light, an incandescent light, or a halogen light. The light emitting direction or the light emitting angle of the light emitted by the heating element  26  can be adjusted to meet different product requirements. For example, the light emitted by the heating element  26  can be adjusted through changing the orientation of the heating element  26 . Alternatively, in some embodiments, a light guiding structure may be provided in the heating element  26 , so that the light emitting direction or the light emitting angle of the light emitted by the heating element  26  can be adjusted through the light guiding structure. Alternatively, in some embodiments, the metal core printed circuit board  25  may be arranged in a sloping manner on the assembling region  212  of the substrate  211 . Hence, through the inclination angle or the inclination direction of the metal core printed circuit board  25 , the light emitting direction or the light emitting angle of the light emitted by the heating element  26  can be adjusted. 
     In some embodiments, the first circuit layer  251  and the second circuit layer  253  of the metal core printed circuit board  25  may be copper circuit layers or silver paste circuit layers and are electrically conductive, where the first circuit layer  251  and the second circuit layer  253  may be formed by etching, printing, or the like. In other words, in this embodiment, the first circuit layer  251  and the second circuit layer  253  may respectively comprise circuits formed by etching, printing, or the like. The metal thermal conductive layer  252  of the metal core printed circuit board  25  may be a metal plate (e.g., a copper plate or an aluminum plate) to perform great thermal conduction and thermal dissipation functions. For example, the thermal conductivity of the metal thermal conductive layer  252  is 200 W/mK or more. The first spacing layer  254  and the second spacing layer  255  allow the first circuit layer  251  and the second circuit layer  253  to be spaced from the metal thermal conductive layer  252 , respectively. Therefore, the first circuit layer  251 , the second circuit layer  253 , and the metal thermal conductive layer  252  can be prevented from contacting each other, and the short-circuited condition of the heating element  26  can be avoided. 
     In some embodiments, the first spacing layer  254  and the second spacing layer  255  may be made of an inorganic insulation material (e.g., ceramic or asbestos), an organic insulation material (e.g., resin, rubber, silk, cotton, or paper), or a composite material obtained by processing the inorganic insulation material and the organic insulation material. Alternatively, in some embodiments, the first spacing layer  254  and the second spacing layer  255  may be thermal conductive insulation layers. For example, the first spacing layer  254  and the second spacing layer  255  may be thermal conductive adhesive layers to provide adhering, insulation, and great thermal conduction functions at the same time. For example, the thermal conductivities of the first spacing layer  254  and the second spacing layer  255  may be 1 W/mK or more. However, it is understood that the foregoing embodiments are provided for illustrative purposes, but not limitations of the instant disclosure. In some embodiments, the first spacing layer  254  and the second spacing layer  255  may be thermal conductive insulation pads (e.g., thermal conductive silicone pads or thermal conductive carbon fiber pads). 
     Furthermore, as shown in  FIG.  3    and  FIG.  4   , the thermal conductivity of the metal core printed circuit board  25  is further greater than the thermal conductivity of the substrate  211 . For example, the overall thermal conductivity of the metal core printed circuit board  25  may be 3 W/mK or more, and the substrate  211  of the circuit board  21  may be a resin substrate (e.g., an FR-4 epoxy resin substrate). Hence, the thermal conductivity of the substrate  211  is 0.4 W/mK or less, which is much less than the thermal conductivity of the metal core printed circuit board  25 . Therefore, the thermal conductivity of the metal core printed circuit board  25  is much greater than the thermal conductivity of the substrate  211 . 
     Based on the above, according to one or some embodiments of the instant disclosure, the heating element  26  is disposed on the metal core printed circuit board  25  rather than directly on the substrate  211 . Hence, because of the high thermal conductivity of the metal core printed circuit board  25 , the heat generated by the heating element  26  during the operation of the heating element  26  can be transmitted and dissipated quickly. Therefore, the temperature of the heating element  26  can be prevented from getting too high to affect the operation efficiency and the service life of the heating element  26 . Moreover, the thermal conductivity of the substrate  211  of the circuit board  21  is less than the thermal conductivity of the metal core printed circuit board  25 ; namely, in this embodiment, the thermal resistance of the substrate  211  is much greater than the thermal resistance of the metal core printed circuit board  25 . Therefore, though the metal core printed circuit board  25  is disposed on the substrate  211 , and the heat generated by the heating element  26  during the operation of the heating element  26  can be transmitted to the substrate  211  through the metal core printed circuit board  25 ; however, owing that the thermal conductivity of the substrate  211  is less than the thermal conductivity of the metal core printed circuit board  25 , the heat generated by the heating element  26  does not cause the overall temperature of the substrate  211  to become too high, thereby preventing the heat generated by the heating element  26  from affecting operations of other components on the substrate  211 . 
     For example, as shown in  FIG.  2    and  FIG.  3   , in this embodiment, the electronic component  215  disposed on the circuit region  213  of the substrate  211  may be a component with poorer heat resistance (e.g., a microphone component which allows the electronic device  1  to receive external voices). In other words, in this embodiment, the maximum allowable temperature of the electronic component  215  during normal operation is less than the maximum allowable temperature of the heating element  26 . Therefore, according to one or some embodiments of the instant disclosure, the heating element  26  that generates high-temperature heat during operation is disposed on the metal core printed circuit board  25 , and the electronic component  215  with poorer thermal resistance is disposed on the circuit region  213  of the substrate  211 . Hence, the heat generated by the heating element  26  can be transmitted and dissipated quickly through the metal core printed circuit board  25 , and the heat generated by the heating element  26  does not cause the temperature of the substrate  211  to become too high. Consequently, the temperature of the electronic component  215  disposed on the substrate  211  can be prevented from exceeding the maximum allowable temperature of the electronic component  215  to cause the electronic component  215  on the substrate  211  to be damaged, failed or even spontaneously ignited. 
     As shown in  FIG.  3   , a protection shield  216  may be provided for covering the electronic component  215  on the circuit region  213  of the substrate  211 . For example, the protection shield  216  may be a rubber shield or a plastic shield, so that the electronic component  215  can be further protected by the protection shield  216 . 
     Further, as shown in  FIG.  4   , the heating element  26  and the first circuit layer  251  of the metal core printed circuit board  25  may be electrically connected to each other through an electrical conductive adhesive layer  30 . For example, the heating element  26  may be soldered and fixed on the first circuit layer  251  through surface-mount technology (SMT), and the heating element  26  is electrically connected to the first circuit layer  251 . Specifically, in this embodiment, the electrical conductive adhesive layer  30  may be a tin paste layer and arranged between the heating element  26  and the first circuit layer  251 . Then, the electrical conductive adhesive layer  30  is processed by a high-temperature melting procedure as well as a cooling and solidification procedure in order, so that the heating element  26  can be soldered and fixed on the first circuit layer  251 . Accordingly, the heating element  26  and the first circuit layer  251  are electrically connected to each other through the electrical conductive adhesive layer  30 . As compared with other fixing manners (such as locking or spot welding), through the electrical conductive adhesive layer  30 , the entire bottom surface of the heating element  26  can be ensured to contact the metal core printed circuit board  25 , thereby not only increasing the thermal conduction area of the heating element  26  to thus enhance the heat dissipation efficiency, but also preventing the heating element  26  from having getting wrapped or deflected after the heating element  26  is soldered and fixed on the first circuit layer  251 . Moreover, through the surface-mount technology, the heating element  26  can be attached to the first circuit layer  251  quickly to reduce labor and time costs. 
       FIG.  6    illustrates a plan view of the electronic device  1  of the exemplary embodiment.  FIG.  7    illustrates an enlarged partial cross-sectional view of the electronic device  1  of the exemplary embodiment. As shown in  FIG.  2   ,  FIG.  6   , and  FIG.  7   , in this embodiment, the housing  10  of the electronic device  1  comprises a light-permissible portion  11 , the circuit board module  20  is disposed in the housing  10 , and the heating element  26  is a light emitting element and corresponds to the light-permissible portion  11 . Therefore, the light emitted by the heating element  26  can pass through the light-permissible portion  11  of the housing  10  to provide a supplementary lighting. For example, the light-permissible portion  11  may be a through hole or a transparent plate. For example, the transparent plate may be made of a transparent material, and the transparent material, for example, may be polycarbonate (PC), polymethyl methacrylate (PMMA), or glass materials, so that a visible light can pass through the light-permissible portion  11 . Alternatively, in some embodiments, the light-permissible portion  11  may be filter plate, so that the light within certain wavelength ranges (e.g., the infrared with a certain wavelength range between 650 nm and 1000 nm) can pass through the light-permissible portion  11 . 
     In some embodiments, the shape of the light-permissible portion  11  corresponds to the shape of the circuit board  21 . For example, as shown in  FIG.  2   , in this embodiment, the light-permissible portion  11  is annular-shaped to correspond to the annular-shaped circuit board  21 . Alternatively, in some embodiments, the light-permissible portion  11  may be several light-permissible regions to correspond to the heating elements  26 , respectively. 
     Further, as shown in  FIG.  2   ,  FIG.  6   , and  FIG.  7   , the housing  10  of the electronic device  1  further comprises at least one thermal conductive cover  12 , and each of the metal core printed circuit boards  25  of the circuit board module  20  further contacts the thermal conductive cover  12 . Therefore, the heat of the metal core printed circuit boards  25  can be transmitted to the thermal conductive cover  12  to enhance the heat dissipation performance of the circuit board module  20 . In some embodiments, the material of the thermal conductive cover  12  may be copper, aluminum, iron, or other metal alloys (e.g., aluminum alloy) to have high thermal conductivity (e.g., the thermal conductivity of the thermal conductive cover  12  is 200 W/mK or more). Hence, heat conduction and dissipation performance of the circuit board module  20  can be further enhanced. 
     As shown in  FIG.  6    and  FIG.  7   , in this embodiment, the thermal conductive cover  12  comprises an inner metal cover  121  and an outer metal cover  122 , and the materials of the inner metal cover  121  and the outer metal cover  122  may be copper, aluminum, iron, or other metal alloys, respectively. The light-permissible portion  11  is connected between the inner metal cover  121  and the outer metal cover  122 . Moreover, one of two sides of the metal core printed circuit board  25  contacts the inner metal cover  121 , and the other side of the metal core printed circuit board  25  contacts the outer metal cover  122 . For example, in this embodiment, a portion of the surface of one of two sides of the metal core printed circuit board  25  contacts the inner metal cover  121  to increase the thermal conduction area, and a side edge of the other side of the metal core printed circuit board  25  protrudes from the substrate  211  and contacts the outer metal cover  122 . Accordingly, the heat of the metal core printed circuit boards  25  can be transmitted to the metal covers (the inner metal cover  121  and the outer metal cover  122 ) at the same time to further enhance the heat dissipation performance. In some embodiments, the metal core printed circuit board  25  may only contact the inner metal cover  121  or the outer metal cover  122 , but embodiments are not limited thereto. 
     Based on the above, in the circuit board module according to one or some embodiments of the instant disclosure, the heating element is disposed on the metal core printed circuit board. Therefore, the heat generated by the heating element upon the operation of the heating element can be quickly transmitted to the substrate of the circuit board through the metal core printed circuit board, so that the temperature of the heating element can be prevented from getting too high. Moreover, according to one or some embodiments of the instant disclosure, the metal core printed circuit board is just disposed on portions of the substrate. Therefore, in these embodiments, the cost for the circuit board module can be greatly reduced, as compared with embodiments having the metal core printed circuit board on the entire substrate. Furthermore, according one or some embodiments of the instant disclosure, the thermal conductivity of the substrate is less than the thermal conductivity of the metal core printed circuit board. Therefore, the heat generated by the heating element can be prevented from affecting operations of other components on the substrate. 
     While the instant disclosure has been described by the way of example and in terms of the preferred embodiments, it is to be understood that the invention need not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.