Patent Publication Number: US-2022225493-A1

Title: Electronic device and circuit board thereof

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an antenna device, and more particularly, to an electronic device having an antenna module and a circuit board thereof. 
     2. Description of Related Art 
     The wireless communication technology has been widely used in various consumer electronic products (such as mobile phones, tablet computers, etc.) to facilitate the reception or transmission of various wireless signals. In order to meet the requirements of portability for consumer electronic products and the convenience for Internet access (such as watching multimedia content), the manufacture and design of wireless communication modules are developed towards the needs of light, thin, and compact. For instance, patch antenna is widely used in wireless communication modules of electronic products due to its small size, light weight and easy manufacturing. 
     As shown in  FIG. 1 , in a conventional electronic device  1 , an antenna module  1   b  is disposed on a mounting surface S of an outer layer structure  10 ′ of a circuit board  1   a  (e.g., a printed circuit board or PCB), and an antenna ground plate  11  electrically connected to the antenna module  1   b  is disposed on a base layer structure  10  of the circuit board  1   a,  where the outer layer structure  10 ′ is disposed on the base layer structure  10 . As such, the antenna ground plate  11  is formed inside the circuit board  1   a.    
     However, in the conventional electronic device  1 , when the antenna module  1   b  is designed to be miniaturized, the antenna radiation efficiency of the antenna module  1   b  would decrease, resulting in a reduction in the operating efficiency of the electronic device  1 , and thus shortening the signal transmission distance of the electronic device  1 . 
     Therefore, how to overcome the above-described drawbacks of the prior art has become an urgent issue in the art. 
     SUMMARY 
     In view of the above-described drawbacks of the prior art, the present disclosure provides a circuit board, which comprises: a circuit board body having an inner layer surface serving as a ground surface; a strip-shaped ground circuit arranged in the circuit board body along edges of the ground surface, wherein the ground circuit occupies at most 50% of an area of the ground surface. 
     In the above-described circuit board, the ground circuit includes at least one annular body. In an example, the annular body has a gap. Further, the ground surface is a polygon, and the gap is located at a corner of the ground surface. 
     The present disclosure further provides an electronic device, which comprises: the aforementioned circuit board, wherein an outer surface of the circuit board is served as a mounting surface; and an antenna module disposed on the mounting surface of the circuit board body and electrically connected to the ground circuit, wherein the antenna module is configured to receive and transmit radiation signals. 
     In the above-described electronic device, a location of the antenna module on the circuit board is different from a location of the gap. 
     In the above-described electronic device, the mounting surface is in a polygon form, and the antenna module is located at a corner of the mounting surface. 
     Therefore, in the electronic device and the circuit board thereof according to the present disclosure, the strip-shaped ground circuit is arranged on the circuit board body along the edges of the ground surface, and the ground circuit occupies at most 50% of the area of the ground surface to improve antenna radiation efficiency of the antenna module, such that the antenna module can continue to be miniaturized and the antenna radiation efficiency can still meet the requirements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of a conventional electronic device. 
         FIG. 2-1  is a schematic perspective view of an electronic device according to the present disclosure. 
         FIG. 2-2  is a schematic upper plan view showing another aspect of  FIG. 2-1 . 
         FIG. 3A ,  FIG. 3B  and  FIG. 3C  are schematic upper plan views showing other embodiments of  FIG. 2-1 . 
     
    
    
     DETAILED DESCRIPTION 
     The following illustrative embodiments are provided to illustrate the present disclosure, these and other advantages and effects can be apparent to those in the art after reading this specification. 
     It should be noted that all the drawings are not intended to limit the present disclosure. Various modifications and variations can be made without departing from the spirit of the present disclosure. Further, terms such as “on,” “a,” etc., are merely for illustrative purposes and should not be construed to limit the scope of the present disclosure. 
       FIG. 2-1  is a schematic perspective view of an electronic device  2  according to the present disclosure. As shown in  FIG. 2-1 , the electronic device  2  includes a circuit board  2   a  and at least one antenna module  2   b  disposed on the circuit board  2   a  for transmitting and/or receiving radiation signals. 
     The circuit board  2   a  includes a circuit board body  20  having a mounting surface  20   a  and at least one strip-shaped ground circuit  21 . 
     In an embodiment, the circuit board body  20  is a hexahedron, and the mounting surface  20   a  is in a polygon form. For example, the mounting surface  20   a  of the circuit board body  20  is a square or rectangular board. 
     Moreover, the circuit board body  20  includes a base layer structure  20 ″ and an outer layer structure  20 ′ formed on the base layer structure  20 ″. An outer surface of the outer layer structure  20 ′ is served as the mounting surface  20   a.  The mounting surface  20   a  is defined with a mounting region A and a functional region B. The mounting region A is arranged with the antenna module  2   b,  and the functional region B is adjacent to the mounting region A. An inner layer surface of the base layer structure  20 ″ for contacting the outer layer structure  20 ′ is served as a ground surface  20   b,  and the ground circuit  21  is arranged on a vertical projection region C of the ground surface  20   b  corresponding to the functional region B. The shape and area of the mounting surface  20   a  are the same as the shape and area of the ground surface  20   b.  For example, the mounting region A is located at a corner of the mounting surface  20   a.    
     Furthermore, the ground circuit  21  is arranged on the circuit board body  20  along the edges of the ground surface  20   b,  and the area of the ground circuit  21  occupying the ground surface  20   b  (i.e., the area of the ground circuit  21  that covers the vertical projection region C) is at most 50% of the area of the ground surface  20   b.    
     In addition, the ground circuit  21  includes at least one annular body, such as a single annular body shown in  FIG. 2-1 . Alternatively, referring to  FIG. 2-2 , a ground circuit  21 ′ has a plurality of looped annular bodies  21   a,    21   b.    
     The antenna module  2   b  is disposed on the mounting surface  20   a  of the circuit board body  20  and electrically connected to the ground circuit  21 ,  21 ′ via circuits of the circuit board  2   a  (not shown). For example, the antenna module  2   b  is located at the mounting region A at the corner of the mounting surface  20   a.    
     In an embodiment, the antenna module  2   b  includes a carrier structure having an electronic element and an antenna structure and a packaging layer for encapsulating the electronic element, and the antenna structure is exposed from the packaging layer. 
     The carrier structure is, for example, a substrate with a core layer and circuit portion, or a coreless substrate with circuit portions, which has an insulator and a circuit layer bonded onto the insulator. The circuit layer is, for example, a fan-out redistribution layer (RDL). The insulator is made of a dielectric material, such as polybenzoxazole (PB  0 ), polyimide (PI), prepreg (PP), etc. It can be understood that the carrier structure can also be other carrier units (such as a lead frame or a silicon interposer) that carry electronic elements (e.g., chips, etc.), and the present disclosure is not limited as such. 
     The electronic element is a semiconductor chip and disposed on the carrier structure. For example, the electronic element is a semiconductor chip capable of transmitting 5G millimeter waves (5G mmWaves) and is electrically connected to the circuit layer, and the antenna structure receives and transmits the required millimeter waves. It can be understood that the ways in which the electronic element can be electrically connected to the carrier structure are not limited to those described above. 
     The antenna structure is in an aspect of an antenna frame or an antenna plate to form a coupled antenna or other transmission types. 
     The packaging layer is made of an insulating material such as polyimide (PI), a dry film, an encapsulant such as an epoxy resin, or a molding compound. The packaging layer can be formed by lamination or molding. 
     It can be understood that there are many types of the antenna module  2   b,  which can be designed according to requirements, and are not limited to the above. 
     Therefore, in the electronic device  2  according to the present disclosure, by adjusting the ground circuit  21 ,  21 ′ on the circuit board  2   a  of a system end, the ground circuit  21 ,  21 ′ occupies at most 50% of the area of the ground surface  20   b  to improve antenna radiation efficiency of the antenna module  2   b,  such that the antenna module  2   b  can continue to be miniaturized and the antenna radiation efficiency can still meet the requirements. 
     Moreover, the ground circuit  21 ,  21 ′ is distributed around the circuit board  2   a  along the edges of the ground surface  20   b  of the circuit board  2   a,  which can effectively improve the antenna radiation efficiency of the antenna module  2   b.    
     Furthermore, an annular body  31   a  of the ground circuit  31  is formed with a gap  310  (e.g., discontinued section shown in  FIG. 3A ) to improve radiation efficiency. For example, the gap  310  is located at a corner of the ground surface  20   b,  that is, the ground circuit  31  is represented by two bent (or L-shaped) wire bodies. Preferably, the location of the antenna module  2   b  on the mounting surface  20   a  is not corresponding to the vertical projection at the gap  310 , that is, the antenna module  2   b  and the gap  310  are located at different corners of the circuit board  2   a  (e.g., the antenna module  2   b  and the gap  310  are located at opposite corners of the circuit board  2   a ), such that the location of the antenna module  2   b  and the location of the gap  310  do not overlap. 
     It can be understood that a ground circuit  31 ′ includes the annular body  31   a  and an annular body  31   b  (as shown in  FIG. 3B ), and a ground circuit  31 ″ includes the annular body  31   a,  the annular body  31   b  and an annular body  31 c (as shown in  FIG. 3C ), where at least one annular body  31   a  is formed with the gap  310 . 
     Therefore, the lower the area occupied by the ground circuit  21  (e.g., the lower the ratio of the area of the ground circuit  21  to the area of the ground surface  20   b ), the better the radiation efficiency of the antenna module  2   b;  and when the ground circuits  31 ,  31 ′,  31 ″ have a gap  310 , the radiation efficiency of the antenna module  2   b  becomes even better, as shown in Table 1. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                 An aspect  
                 An aspect  
                 An aspect  
               
               
                   
                   
                   
                 of a single  
                 of double  
                 of triple  
               
               
                   
                 An  
                 An aspect  
                 annular 
                 annular 
                 annular 
               
               
                   
                 aspect 
                 of a single  
                 body  
                 body  
                 body  
               
               
                   
                 of the  
                 annular 
                 having  
                 having  
                 having  
               
               
                   
                 prior art 
                 body 
                 a gap 
                 a gap 
                 a gap 
               
               
                   
                 (FIG. 1) 
                 (FIG. 2-1) 
                 (FIG. 3A) 
                 (FIG. 3B) 
                 (FIG. 3C) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Ratio 
                 &gt;50% 
                 32% 
                 26% 
                 45% 
                 50% 
               
               
                 Radiation 
                  55% 
                 59% 
                 72% 
                 66% 
                 61% 
               
               
                 efficiency 
               
               
                   
               
            
           
         
       
     
     Therefore, in the electronic device  2  and the circuit board  2   a  thereof according to the present disclosure, the ground circuit  21  occupies at most 50% of the area of the ground surface  20   b  to improve antenna radiation efficiency, so that the antenna module  2   b  can continue to be miniaturized and the antenna radiation efficiency can still meet the requirements. 
     In addition, according to a first feature of the present disclosure, the ground circuit  21  is distributed around the circuit board  2   a  with respect to an axis L of a central axis along the edges of the ground surface  20   b  of the circuit board  2   a,  and the area of the ground circuit  21  occupying the area of the ground surface  20   b  is not greater than 50% of the area of the ground surface  20   b  so as to improve antenna radiation efficiency; according to a second feature of the present disclosure, the lower the area occupied by the ground circuit  21  (e.g., the lower the ratio of the area of the ground circuit  21  to the area of the ground surface  20   b ), the better the radiation efficiency; and according to a third feature of the present disclosure, radiation efficiency becomes even better when the ground circuits  31 ,  31 ′,  31 ″ have at least one gap  310 . Table 2 illustrates the aforementioned three features of the present disclosure in the order of antenna efficiency. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Structural 
                 First  
                 First feature plus  
                 First feature plus second  
               
               
                 design 
                 feature 
                 second feature 
                 feature and third feature 
               
               
                   
               
             
            
               
                 Antenna 
                 Good 
                 Great 
                 Excellent 
               
               
                 efficiency 
               
               
                   
               
            
           
         
       
     
     The above-described descriptions of the detailed embodiments are to illustrate the preferred implementation according to the present disclosure, and it is not to limit the scope of the present disclosure. Accordingly, all modifications and variations completed by those with ordinary skill in the art should fall within the scope of present disclosure defined by the appended claims.