Patent Publication Number: US-2022240391-A1

Title: Circuit board, preparation method thereof, and electronic device

Description:
CROSS REFERENCE 
     The present application is a continuation-application of International (PCT) Patent Application No. PCT/CN2021/084601, filed on Mar. 31, 2021, which claims foreign priority of Chinese Patent Application No. 202110114037.7, filed on Jan. 27, 2021, in the China National Intellectual Property Administration, the entire contents of which are hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of printed circuit board technologies, and in particular to a circuit board, a preparation method thereof, and an electronic device. 
     BACKGROUND 
     In an existing printed circuit board, multiple electronic components may be arranged. To dissipate heat from a predetermined electronic component, a metal base may usually be buried in the printed circuit board. The electronic component may be arranged directly above the metal base and connected to the metal base, such that the electronic component can be dissipated through the metal base. 
     In the related art, an area corresponding to the metal base on the printed circuit board usually cannot be arranged with conductive lines, which leads to the problem of poor utilization of wiring space on the printed circuit board. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure provides a circuit board and a preparation method thereof, to solve the problem that the area corresponding to a metal base on a printed circuit board in the prior art usually cannot be provided with conductive lines, resulting in poor utilization of wiring space on the printed circuit board. 
     To solve the above technical problem, a technical solution adopted by the present disclosure is to provide a circuit board, comprising: a substrate, defining a first through-hole; a metal block, embedded in the first through-hole and fixedly connected to the substrate; a conductive line layer, arranged on at least one side surface of the substrate; wherein the conductive line layer partially covers an opening of the first through-hole on a corresponding side surface of the substrate; and a conductive channel, penetrating the conductive line layer and the metal block in turn; wherein the conductive channel comprises a second through-hole and a conductive medium plated on a wall of the second through-hole; an end of the conductive medium is connected to the conductive line layer, and another end of the conductive medium is connected to the metal block. 
     In some embodiments, the metal block is fixedly connected to the substrate through a connection layer; the connection layer is configured to fill a gap between the first through-hole and the metal block. 
     In some embodiments, the second through-hole is made of a semi-curable material. 
     In some embodiments, the conductive channel comprises a plurality of conductive channels, and at least two of the plurality of conductive channels are spaced apart; the conductive line layer is electrically connected to the metal block through at least one of the plurality of conductive channels. 
     In some embodiments, each of opposite sides of the substrate is covered with the conductive line layer; two layers of the conductive line layer partially cover openings of the first through-hole located on the opposite sides of the substrate; each of the two layers of the conductive line layer is electrically connected to the metal block through at least one of the plurality of conductive channels. 
     In some embodiments, the metal block is accommodated in a holding space defined by the connection layer, and the connection layer does not protrude out of first through-hole; the conductive channel penetrates the connection layer and is connected to the metal block. 
     In some embodiments, the conductive line layer comprises a plurality of conductive lines having a predetermined pattern. 
     To solve the above technical problem, another technical solution adopted by the present disclosure is to provide a circuit board preparation method, comprising: preparing a substrate, wherein the substrate defines a first through-hole; embedding a metal block in the first through-hole for fixedly connecting the metal block and an inner wall of the first through-hole; arranging a conductive line layer on at least one side surface of the substrate, wherein the conductive line layer partially covers an opening of the first through-hole on a corresponding side surface of the substrate; and arranging a conductive channel connected to the metal block in a side of the conductive line layer back to the substrate, such that the conductive line layer is electrically connected to the metal block through the conductive channel 
     In some embodiments, the embedding the metal block in the first through-hole comprises: preparing a connection block, wherein the connection block defines a holding space; placing the metal block in the holding space, such that the metal block and the connection block form an assembly; and pressing the assembly into the first through-hole of the substrate. 
     In some embodiments, the connection block has a predetermined shape matching a shape of the first through-hole or being larger than the shape of the first through-hole. 
     In some embodiments, the arranging the conductive channel connected to the metal block in the side of the conductive line layer back to the substrate comprises: defining a second through-hole connected to the metal block from the side of the conductive line layer back to the substrate; and filling a conductive medium in the second through-hole. 
     In some embodiments, the second through-hole is formed by laser drilling and forming; the conductive medium is formed on a wall of the second through-hole by electroplating forming. 
     In some embodiments, after the arranging the conductive channel connected to the metal block in the side of the conductive line layer back to the substrate, the method further comprises: patterning the conductive line layer to form a plurality of conductive lines having a predetermined pattern. 
     To solve the above technical problem, further another technical solution adopted by the present disclosure is to provide an electronic device, comprising: a circuit board as above. 
     In contrast to the prior art, the present disclosure provides a circuit board, a preparation method thereof, and an electronic device. The conductive line is electrically connected to the metal block through the conductive channel, and a position adjacent to the conductive line may be configured to arrange other conductive lines. The other conductive lines described herein may be spaced or connected to the conductive lines. A projection of the other conductive lines in a plane perpendicular to the axis of the conductive channel can at least partially coincide with the projection of the metal block. Therefore, the wiring density of the board can be increased, thereby improving the space utilization efficiency of the board. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to more clearly describe the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. 
         FIG. 1  is a structural schematic view of a circuit board according to an embodiment of the present disclosure. 
         FIG. 2  is a flowchart of a circuit board preparation method according to an embodiment of the present disclosure. 
         FIGS. 3 a    is a schematic view of a structural change of a circuit board prepared in the method as shown in  FIG. 2 . 
         FIGS. 3 b    is a schematic view of another structural change of a circuit board prepared in the method as shown in  FIG. 2 . 
         FIGS. 3 c    is a schematic view of further another structural change of a circuit board prepared in the method as shown in  FIG. 2 . 
         FIGS. 3 d    is a schematic view of further another structural change of a circuit board prepared in the method as shown in  FIG. 2 . 
         FIGS. 3 e    is a schematic view of further another structural change of a circuit board prepared in the method as shown in  FIG. 2 . 
         FIG. 4  is a structural schematic view of an electronic device according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following will be a clear and complete description of the technical solutions in the embodiments of the present disclosure in conjunction with the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, and not all of them. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without making creative labor fall within the scope of the present disclosure 
     It should be noted that when there are directional indications (such as up, down, left, right, forward, back) involved in the embodiments of the present disclosure, the directional indications are only intended to explain a relative position relationship, movement, etc. between components in a particular attitude (as shown in the attached drawings). When the particular attitude is changed, the directional indications are also changed accordingly. 
     In addition, when there is a description of “first”, “second”, etc. in the embodiments of the present disclosure, the description of “first”, “second”, etc. is intended for descriptive purposes only and is not to be understood as indicating or implying its relative importance or implicitly specifying the number of indicated technical features. Thus, features qualified with “first” and “second” may explicitly or implicitly include at least one such feature. In addition, the technical solutions of each embodiment may be combined with each other, but only on the basis of the technical solutions that can be realized by those skilled in the art. When the combination of technical solutions appears to be contradictory or unrealizable, such combination of technical solutions shall be considered not to exist and not to be within the scope claimed in the present disclosure. 
     Referring to  FIG. 1 ,  FIG. 1  is a structural schematic view of a circuit board according to an embodiment of the present disclosure. 
     The circuit board  10  includes a substrate  100 , a metal block  200 , a conductive line layer  300 , and a conductive channel  400 . 
     The substrate  100  defines a first through-hole  110 . The metal block  200  is embedded in the first through-hole  110  and fixedly connected to the substrate  100 . 
     The metal block  200  may be embedded in the first through-hole  110  through a connection layer  120 . Specifically, the connection layer  120  is configured to fill a gap between the first through-hole  110  and the metal block  200 , such that the metal block  200  is fixedly connected to an inner wall of the first through-hole  110  through the connection layer  120 . 
     In the embodiment, the connection layer  120  may be arranged around the metal block  200 , i.e., the connection layer  120  defines a holding space inside the connection layer  120 , and the metal block  200  is accommodated in the holding space inside the connection layer  120 . In the embodiment, the material of the connection layer  120  may be a semi-curable material, for example, may be a polypropylene (PP) material. 
     Specifically, the metal block  200  may be arranged into the holding space inside the connection layer  120 , and then a assembly formed by the metal block  200  and the connection layer  120  is pressed into the first through-hole  110  and heated at the same time, such that the connection layer  120  can be filled in the gap between the first through-hole  110  and the metal block  200 . In this way, after the connection layer  120  is cured, the metal block  200  may be fixedly connected to the substrate  100 . A thickness of the metal block  200  is less than or equal to a thickness of the substrate  100 . When the metal block  200  is arranged into the first through-hole  110 , the metal block  200  does not protrude out of the first through-hole  110 . 
     The conductive line layer  300  is covered on a side surface with an opening of the first through-hole  110  of the substrate  100 . The conductive line layer  300  may be formed of a metal conductive material to form a conductive metal part. For example, a metal sheet such as copper foil may be arranged on the surface of the substrate  100  to form the conductive line layer  300 . 
     In the embodiment, the circuit board  10  further includes the conductive channel  400 . The conductive channel  400  penetrates the conductive line layer  300  and is then electrically connected to the metal block  200 . Specifically, the conductive channel  400  includes a second through-hole  410  and a metal medium  420  arranged in the second through-hole  410 . The second through-hole  410  penetrates the conductive line layer  300  and the connection layer  120  in turn and is connected to a surface of the metal block  200 . The metal medium  420  is filled in the second through-hole  410 . An end of the metal medium  420  is electrically connected to a preset conductive line in the conductive line layer  300 , and the other end of the metal medium  420  is electrically connected to the metal block  200 . 
     In the embodiment, the second through-hole  410  may be formed by laser drilling or mechanical drilling. By punching a hole into the first through-hole  110  of the substrate  100  from a side of the conductive line layer  300  back to the substrate  100 , the second through-hole  410  can be formed that connects to the surface of the metal block  200 . Therefore, by using laser drilling or mechanical drilling of the conductive line layer  300  to open the second through-hole  410 , and then arranging the metal medium  420  in the second through-hole  410 , a compact heat dissipation channel may be formed, such that a part of the conductive line layer  300  above the opening of the first through-hole  110  may also be performed with wiring operations, thereby improving the space utilization efficiency of the circuit board. 
     In the embodiment, the metal medium  420  may be filled within the second through-hole  410  by electroforming of electroplating. The metal medium  420  may be completely filled within an interior space of the second through-hole  410 . In other embodiments, the metal medium  420  may also be affixed to an inner wall of the second through-hole  410  and a central portion of the second through-hole  410  is not filled with the metal medium  420 . 
     Referring further to  FIG. 1 . 
     In the embodiment, the number of the conductive channels  400  may be more than one, and each of the conductive channels  400  extends from an opening position of the first through-hole  110  to the surface of the metal block  200 . The plurality of conductive channels  400  are spaced apart, and the conductive line layer  300  may be electrically connected to the metal block  200  through at least one of the conductive channels  400 . 
     The conductive line layer  300  may be patterned such that the conductive line layer  300  may form a plurality of conductive lines that form a predetermined pattern. 
     In the embodiment, an end of a conductive channel  400  may be electrically connected to one of the conductive lines, and the other end is electrically connected to the metal block  200 . The conductive line electrically connected to the conductive channel  400  may be a pad for soldering fixed an electronic component. Heat generated by the electronic component may be transferred to the metal block  200  through the conductive line and the conductive channel  400 , and then exported through the metal block  200 . 
     In the embodiment, the conductive line layer  300  is electrically connected to the metal block  200  through the conductive channel(s)  400 , and a position adjacent to the conductive line may be configured to arrange other conductive lines. The other conductive lines described herein may be spaced or connected to the conductive lines. A projection of the other conductive lines in a plane perpendicular to an axis of the conductive channel(s)  400  may be at least partially coincident with a projection of the metal block  200 . Therefore, a wiring density of the circuit board  10  may be increased, thereby improving the space utilization efficiency of the circuit board  10 . 
     In the embodiment, two sides of the substrate  100  with different openings of the first through-hole  110  are each covered with the conductive line layer  300  as described above. Each conductive line layer  300  may include the at least one conductive channel  400  connected to a corresponding surface of the metal block  200  and electrically connected to the metal block  200 . 
     The electronic component may be arranged on the conductive line layer  300  on a side of the substrate  100 , and the heat generated by the electronic component may be conducted to the other side of the substrate  100  through the at least one conductive channel  400  and the metal block  200 . 
     Referring to  FIG. 2 , and further referring to  FIGS. 3 a -3 e   ,  FIG. 2  is a flowchart of a circuit board preparation method according to an embodiment of the present disclosure, and  FIGS. 3 a   - FIG. 3 e    are schematic views of structural changes of a circuit board prepared in the method as shown in  FIG. 2 . 
     The circuit board preparation method may include operations at blocks as followed. 
     At block S 110 : A substrate is prepared, wherein the substrate defines a first through-hole. 
     In this step, the substrate is made of insulating material. The substrate may be made of PP material, or other insulating material, without limitation herein. 
     In this step, referring to  FIG. 3 a   , the preparing the substrate includes: forming the substrate  100  with a predetermined shape and size, and then defining the first through-hole  110  at a predetermined position of the substrate  100 . The number of the first through-hole  110  may be one or more. 
     At block S 120 : A metal block is embedded in the first through-hole for fixedly connecting the metal block and an inner wall of the first through-hole. 
     In this step, referring to  FIG. 3 b   , when the first through-hole  110  is defined in the substrate  100 , the metal block  200  in a suitable size may be selected and embedded in the first through-hole  110  such that the metal block  200  is fixedly connected to the inner wall of the first through-hole  110 . The metal block  200  in the suitable size may be pre-formed by casting or machining and other manufacturing methods. 
     In this step, after the metal block  200  is embedded in the first through-hole  110 , the metal block  200  does not protrude out of the first through-hole  110 . 
     The embedding the metal block  200  in the first through-hole may specifically include the following operations. 
     a. A connection block with a predetermined shape is prepared, and a holding space is defined in the connection block. 
     The connection block has a predetermined shape, which may be set to match the shape of the first through-hole  110 , or the predetermined shape may be slightly larger than the shape of the first through-hole  110 . For example, when the first through-hole  110  is cylindrical, the connection block may be a cylindrical shape with dimensions slightly larger than the cylindrical first through-hole  110 , i.e., the radius of the connection block may be slightly greater than the radius of the first through-hole  110 , or the height of the connection block may be slightly greater than the depth of the first through-hole  110 . 
     In this step, the holding space is defined in the connection block. The holding space may be formed by machining or laser drilling the connection block. 
     b. The metal block  200  is placed in the holding space, such that the metal block  200  and the connection block form an assembly. 
     When the holding space is defined in the connection block, the metal block  200  is placed in the holding space; then an opening of the holding space is closed, such that the metal block  200  may be encased in the holding space of the connection block. Therefore, the metal block  200  may form a fixedly connected assembly with the connection block. 
     c. The assembly is pressed into the first through-hole of the substrate. 
     The assembly formed by the metal block  200  and the connection block is arranged into the first through-hole  110  by means of hot pressing, which in turn enables the assembly formed by the metal block  200  and the connection block to be filled in the first through-hole  110 . 
     Since the connection block is made of semi-curing material. When the hot pressing is completed, the assembly formed by the metal block  200  and the connection block may be filled in the first through-hole  110 , and the semi-curing sheet may be fixedly connected to the inner wall of the first through-hole  110 . That is, the metal block  200  may be fixedly connected to the inner wall of the first through-hole  110  by the connection block. In this way, the metal block  200  is fixedly connected to the substrate  100 . 
     The connection block may be configured to form a connection layer  120 . 
     At block S 130 : A conductive line layer is arranged on at least one side surface of the substrate, wherein the conductive line layer is partially covered on an opening of the first through-hole on a corresponding surface of the substrate. 
     In this step, referring to  FIG. 3 c   , when the assembly formed by the metal block and the connection block is embedded in the first through-hole, the conductive line layer  300  is covered on the substrate. The conductive line layer  300  is covered on a surface of the substrate with an opening of the first through-hole. 
     In this step, the conductive line layer  300  may be formed by a metal film, for example, the metal film may be a copper foil. The conductive line layer  300  may be arranged on a surface of at least one side of the substrate  100 , and a part of the conductive line layer  300  may be covered on an opening of the first through-hole  110  located on a corresponding surface of the substrate  100 . The conductive line layer  300  may be directly affixed to the surface of the substrate  100 ; or the conductive line layer  300  may be fixed to the surface of the substrate  100  by using an adhesive layer. The adhesive layer may be formed by a semi-curing sheet. 
     The conductive line layer  300  may also be pressed onto the surface of the substrate  100  by means of heating and pressing. When the conductive line layer  300  is pressed on the substrate  100 , the semi-curing sheet is attached to the surface of the substrate  100 , and the conductive line layer is arranged on a surface of the semi-curing sheet back to the substrate  100 . By the hot pressing operation, the semi-curing sheet can form the adhesive layer to fixedly bond the conductive line layer  300  to the substrate  100 . 
     In this step, the conductive line layer  300  may be covered on both sides of the substrate  100  with different openings of the first through-hole  110 . 
     At block S 140 : A conductive channel connected to the metal block is arranged in a side of the conductive line layer back to the substrate, such that the conductive line layer is electrically connected to the metal block through the conductive channel 
     In this step, referring to  FIG. 3 d    and  FIG. 3 e   , when the conductive line layer  300  is covered to the substrate  100 , the conductive channel  400  connected to the metal block  200  may be arranged from the side of the conductive line layer  300  into the first through-hole  110  of the substrate  100 . 
     The number of the conductive channels  400  may be one or more. 
     When the substrate  100  is arranged with the conductive line layer  300  on two sides with different openings of the first through-hole  110 , i.e., when both sides of the substrate  100  are covered with the conductive line layers  300  on opposite sides. At least one conductive channel  400  connected to the metal block  200  may be arranged in each of the conductive line layers  300 . 
     The conductive channel  400  includes a second through-hole  410  and a metal medium  420  arranged in the second through-hole  410 . The step of forming the conductive channel  420  may include operations as followed. 
     The second through-hole  420  connected to the metal block is defined from the side of the conductive line layer  300  back to the substrate  100 . The second through-hole  420  penetrates the conductive line layer  300  and connection layer  120  in turn to connect to the surface of the metal block  200 . The second through-hole  410  can be formed by means of mechanical drilling, or can also be formed by means of laser drilling. 
     Then, the metal medium  420  is filled in the second through-hole  410 , such that an end of the metal medium  420  is connected to the conductive line layer  300  and the other end is directly connected to the metal block  200 . 
     The metal medium  420  may be filled in the second through-hole  410  by electroplating; or it is also possible to prepare a liquefied material of the metal medium first, and then the liquefied material of the metal medium is injected into the second through-hole  410  and solidified, such that the conductive channel  400  may be achieved. 
     Further, the present disclosure provides an electronic device. Referring to  FIG. 4 ,  FIG. 4  is a structural schematic view of an electronic device according to an embodiment of the present disclosure. 
     The electronic device  50  includes a circuit board  10  and a functional component  510  as previously described. The functional component  510  may be a power device such as a chip, controller, etc., and the functional component  510  may be mounted on a conductive line layer  300  on a side of the substrate  100 . 
     Each conductive line layer  300  may be patterned to form a plurality of conductive lines  321  with a predetermined pattern, and both conductive line layers  300  on opposite sides of the substrate  100  have at least one conductive line  321  to connect to the metal block  200  via the conductive channel  400 . 
     The functional component  510  may be mounted on the conductive line layer  300  on a side of the substrate  100  and may be further connected to the conductive line layer  300  on the other side of the substrate  100  through the metal block  200  and the conductive channel  400  on the other side of the metal block  200 , such that heat generated by the functional component  510  can be transferred to the conductive line layer  300  on the other side through the conductive channel  400  and the metal block  200  to achieve the heat dissipation function. 
     In summary, the present disclosure provides a circuit board and a preparation method thereof. A conductive line is electrically connected to the metal block through the conductive channel, and a position adjacent to the conductive line may be configured to arrange other conductive lines. The other conductive lines described herein may be spaced or connected to the conductive line. A projection of the other conductive lines in a plane perpendicular to an axis of the conductive channel may be at least partially coincident with a projection of the metal block. Therefore, a wiring density of the circuit board may be increased, thereby improving the space utilization efficiency of the circuit board. 
     The above description is only an implementation of the present disclosure, and is not intended to limit the scope of the present disclosure. Any equivalent structure or equivalent process transformation using the contents of the specification and the accompanying drawings, or direct or indirect application in other related technical fields, is included in the scope of the present disclosure.