Patent Publication Number: US-2023164907-A1

Title: Flexible printed circuit board and display device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The application is a US National Stage of International Application No. PCT/CN2021/098640, filed on Jun. 7, 2021, which claims priority from Chinese Patent Application No. 202010525689.5, entitled “FLEXIBLE PRINTED CIRCUIT (FPC) BOARD AND DISPLAY APPARATUS”, filed with the China National Intellectual Property Administration on Jun. 10, 2020, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to the technical field of display, in particular to a flexible printed circuit board and a display apparatus. 
     BACKGROUND 
     In an existing organic light-emitting diode (OLED) touch display apparatus, a touch panel is often disposed outside an encapsulation layer. In order to realize simultaneous control of touch and display, a flexible printed circuit (FPC) board made of multiple layers is often used to realize circuit connection with a printed circuit board (PCB). 
     However, the existing flexible printed circuit board made of multiple layers has the technical problems of great manufacturing difficulty and high cost. 
     SUMMARY 
     In a first aspect, an embodiment of the disclosure provides a flexible printed circuit board, including: a main flexible printed circuit board and an adaptor flexible printed circuit board. The main flexible printed circuit board is a single-layer board or a double-layer board, and includes a bonding region configured for bonding with a display panel, a component arranging region configured for arranging a control component, a first connection region configured for connecting with an adaptor flexible printed circuit board, a first signal line disposed between the component arranging region and the first connection region, and a second signal line disposed between the component arranging region and the bonding region. The adaptor flexible printed circuit board has an outline different from an outline of the main flexible printed circuit board, and the adaptor flexible printed circuit board is a single-layer board or a double-layer board, and includes a second connection region configured for connecting with the main flexible printed circuit board, a third connection region configured for connecting with a printed circuit board, and a third signal line disposed between the second connection region and the third connection region. An orthographic projection of the second connection region on the main flexible printed circuit board completely falls within a region range of the main flexible printed circuit board, and an orthographic projection of the third connection region on a plane of the main flexible printed circuit board does not fall within the region range of the main flexible printed circuit board. The main flexible printed circuit board and the adaptor flexible printed circuit board are connected through the first connection region and the second connection region respectively, an orthographic projection of the third signal line on the main flexible printed circuit board and the second signal line has an overlapping region, and in the overlapping region, an electromagnetic shielding structure is at least disposed on a side of the main flexible printed circuit board facing the adaptor flexible printed circuit board or on a side of the adaptor flexible printed circuit board facing the main flexible printed circuit board. 
     In some embodiments, the main flexible printed circuit board includes a first substrate layer, a first conductive layer disposed on a first surface of the first substrate layer, and a second conductive layer disposed on a second surface of the first substrate layer opposite to the first surface. The first surface is a surface of the first substrate layer close to the adaptor flexible printed circuit board. The first conductive layer includes the first signal line, and the second conductive layer includes the second signal line. The electromagnetic shielding structure is disposed on the side of the main flexible printed circuit board facing the adaptor flexible printed circuit board, and in the overlapping region, the electromagnetic shielding structure includes a first conductive part disposed in the first conductive layer. The first conductive part is insulated from the first signal line, and the first conductive part is grounded. 
     In some embodiments, the adaptor flexible printed circuit board includes a second substrate layer, and a third conductive layer disposed on a third surface of the second substrate layer. The third surface is a surface of the second substrate layer facing away from the main flexible printed circuit board, and the third conductive layer includes the third signal line. 
     In some embodiments, the adaptor flexible printed circuit board includes a third substrate layer, a fourth conductive layer disposed on a fourth surface of the third substrate layer, and a fifth conductive layer disposed on a fifth surface of the third substrate layer opposite to the fourth surface. The fifth surface is a surface of the third substrate layer close to the main flexible printed circuit board, and the fourth conductive layer includes a third signal line. The electromagnetic shielding structure is disposed on the side of the adaptor flexible printed circuit board facing the main flexible printed circuit board, and in the overlapping region, the electromagnetic shielding structure includes a second conductive part disposed in the fifth conductive layer, and the second conductive part is grounded. 
     In some embodiments, in the overlapping region, the electromagnetic shielding structure includes a first electromagnetic shielding layer disposed on the side of the main flexible printed circuit board facing the adaptor flexible printed circuit board, and/or, a second electromagnetic shielding layer disposed on the side of the adaptor flexible printed circuit board facing the main flexible printed circuit board. 
     In some embodiments, a first covering film is disposed on the side of the main flexible printed circuit board facing the adaptor flexible printed circuit board, and the first electromagnetic shielding layer is disposed on a side of the first covering film close to the adaptor flexible printed circuit board. 
     In some embodiments, the first electromagnetic shielding layer is one or more of conductive rubber, conductive cloth, conductive foam or conductive shielding glue, and the second electromagnetic shielding layer is one or more of the conductive rubber, the conductive cloth, the conductive foam or the conductive shielding glue. 
     In some embodiments, the main flexible printed circuit board and the adaptor flexible printed circuit board are connected in the first connection region and the second connection region respectively through one of a board-to-board (BTB) connector, a zero-insertion-force (ZIF) connector and FOF bonding. 
     In some embodiments, a second covering film is disposed on a side of the second conductive layer facing away from the first substrate layer. 
     In some embodiments, a third covering film is disposed on a side of the third conductive layer facing away from the second substrate layer. 
     In a second aspect, an embodiment of the disclosure provides a display apparatus, including: a display panel, and a flexible printed circuit board. The flexible printed circuit board includes a main flexible printed circuit board and an adaptor flexible printed circuit board. The main flexible printed circuit board is a single-layer board or a double-layer board, and includes a bonding region configured for bonding with a display panel, a component arranging region configured for arranging a control component, a first connection region configured for connecting with an adaptor flexible printed circuit board, a first signal line disposed between the component arranging region and the first connection region, and a second signal line disposed between the component arranging region and the bonding region. The adaptor flexible printed circuit board has an outline different from an outline of the main flexible printed circuit board, and the adaptor flexible printed circuit board is a single-layer board or a double-layer board, and includes a second connection region configured for connecting with the main flexible printed circuit board, a third connection region configured for connecting with a printed circuit board, and a third signal line disposed between the second connection region and the third connection region. An orthographic projection of the second connection region on the main flexible printed circuit board completely falls within a region range of the main flexible printed circuit board, and an orthographic projection of the third connection region on a plane of the main flexible printed circuit board does not fall within the region range of the main flexible printed circuit board. The main flexible printed circuit board and the adaptor flexible printed circuit board are connected through the first connection region and the second connection region respectively, an orthographic projection of the third signal line on the main flexible printed circuit board and the second signal line has an overlapping region, and in the overlapping region, an electromagnetic shielding structure is at least disposed on a side of the main flexible printed circuit board facing the adaptor flexible printed circuit board or on a side of the adaptor flexible printed circuit board facing the main flexible printed circuit board. 
     In some embodiments, the display panel includes: pixel units arranged in an array, and a first functional line electrically connected with the pixel units. The first functional line is electrically connected with the third signal line on the flexible printed circuit board through the bonding region, and the first functional line is configured to receive a display signal from the flexible printed circuit board. 
     In some embodiments, the display panel further includes: a touch layer, disposed on a side of the pixel units away from a base substrate, and includes a plurality of first touch electrodes and a plurality of second touch electrodes; and a second functional line electrically connected with the first touch electrodes, and a third functional line electrically connected with the second touch electrodes. The second functional line is electrically connected with a first sub-line in the second signal line on the flexible printed circuit board through the bonding region, and the third functional line is electrically connected with a second sub-line in the second signal line on the flexible printed circuit board through the bonding region. One of the second functional line and the third functional line is configured to receive a touch signal, and the other of the second functional line and the third functional line is configured to send the touch signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic structural diagram of a flexible printed circuit board of six-layers. 
         FIG.  2    is a schematic structural diagram showing the six-layers of the flexible printed circuit board shown in  FIG.  1   . 
         FIG.  3    is a schematic structural diagram of a flexible printed circuit board provided by an embodiment of the disclosure. 
         FIG.  4    is a schematic diagram showing region division of a main flexible printed circuit board in a flexible printed circuit board provided by an embodiment of the disclosure. 
         FIG.  5    is a schematic diagram showing region division of an adaptor flexible printed circuit board in a flexible printed circuit board provided by an embodiment of the disclosure. 
         FIG.  6    is a schematic sectional view of the main flexible printed circuit board in the flexible printed circuit board along a direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  7    is a schematic structural diagram of wiring of a first layer of the main flexible printed circuit board in  FIG.  6   . 
         FIG.  8    is a schematic structural diagram of wiring of a second layer of the main flexible printed circuit board in  FIG.  6   . 
         FIG.  9    is a schematic top view of a first surface of the main flexible printed circuit board in  FIG.  6   . 
         FIG.  10    is a schematic sectional view of the adaptor flexible printed circuit board in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  11    is a schematic sectional view of the adaptor flexible printed circuit board in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  12    is a schematic sectional view of the main flexible printed circuit board in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  13    is a schematic sectional view of the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  14    is a schematic structural diagram of the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  15    is a schematic sectional view of the main flexible printed circuit board in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  16    is a schematic sectional view of the main flexible printed circuit board in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  17    is a schematic sectional view of the adaptor flexible printed circuit board in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  18    is a schematic sectional view of the main flexible printed circuit board in the flexible printed circuit board along the direction indicated by NN′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  19    is a schematic sectional view of the main flexible printed circuit board in the flexible printed circuit board along the direction indicated by NN′ in  FIG.  3    provided by an embodiment of the disclosure. 
         FIG.  20    is a schematic diagram of the layout of the flexible printed circuit board shown in  FIG.  1   . 
         FIG.  21    is a schematic diagram of the layout of the flexible printed circuit board provided by an embodiment of the disclosure. 
         FIG.  22    is a schematic structural diagram of a display apparatus provided by an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     To make the objectives, technical solutions and advantages of embodiments of the disclosure clearer, the technical solutions of the embodiments of the disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the disclosure. Apparently, the described embodiments are only a part of the embodiments of the disclosure, not all of the embodiments. The embodiments of the disclosure and features in the embodiments can be combined with each other in the case of not conflicting. Based on the described embodiments of the disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the disclosure. 
     Unless otherwise defined, technical or scientific terms used in the disclosure shall have the ordinary meanings understood by those ordinarily skilled in the art to which the disclosure pertains. The words “comprise” or “include” and the like used in the disclosure indicate that an element or item appearing before such word covers listed elements or items appearing after the word and equivalents thereof, and does not exclude other elements or items. 
     It needs to be noted that the sizes and shapes of all figures in the accompanying drawings do not reflect true scales, and are only intended to schematically illustrate the content of the disclosure. The same or similar reference numerals represent the same or similar elements or elements with the same or similar functions all the time. 
     In the related art, a structure of a flexible printed circuit board made of six-layer board can be seen in in  FIG.  1   . In a general multilayer board, a GND layer is usually disposed between a power line  01  and a touch line  02  (including, for example, an Rx line  021  and a Tx line  022  shown in  FIG.  1   ) to ensure the shielding between the two types of lines.  FIG.  2    is a schematic diagram showing the six-layers of the board shown in  FIG.  1   . Specifically, a first layer includes a device line  05  connected with a touch driving device  03  and a display driving device  04 , a second layer includes the power line  01 , a third layer includes the Rx line  021  and a part of a display line  06 , a fourth layer and a fifth layer include a shielding layer  07 , and a sixth layer is the Tx line  022 . The touch lines  02  in the third layer and the sixth layer pass over the power line  01  in the second layer, and the shielding between them is realized through the shielding layer  07  of the fourth layer and the fifth layer. Since the multilayer board usually includes four layers, six layers or even more layers, the flexible printed circuit board of the multilayer has the technical problems of complex manufacturing process and high manufacturing cost. 
     In view of this, embodiments of the disclosure provide a flexible printed circuit board and a display apparatus, which are configured to simplify the manufacturing process of the flexible printed circuit board and reduce the manufacturing cost of the flexible printed circuit board. 
     In combination with  FIG.  3    to  FIG.  5   , as shown in  FIG.  3   , which is a schematic structural diagram of a flexible printed circuit board provided by an embodiment of the disclosure,  FIG.  4    is a schematic diagram of region division of a main flexible printed circuit board  1 ,  FIG.  5    is a schematic diagram of region division of an adaptor flexible printed circuit board  2 . In some embodiments, the flexible printed circuit board includes:
         the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  with an outline different from the main flexible printed circuit board  1 , the main flexible printed circuit board  1  is a single-layer board or double-layer board, and the adaptor flexible printed circuit board  2  is a single-layer board or double-layer board;   the main flexible printed circuit board  1  includes a bonding region A configured for bonding with a display panel, a component arranging region B configured for arranging a control component, a first connection region C configured for connecting with the adaptor flexible printed circuit board  2 , and a signal line  3 , and the signal line  3  includes a first signal line  31  disposed between the component arranging region B and the first connection region C, and a second signal line  32  disposed between the bonding region A and the component arranging region B;   the adaptor flexible printed circuit board  2  includes a second connection region D configured for connecting with the main flexible printed circuit board  1 , a third connection region E configured for connecting with a PCB, and a third signal line  33  disposed between the second connection region D and the third connection region E, and an orthographic projection of the second connection region D on the main flexible printed circuit board  1  completely falls within a region range of the main flexible printed circuit board  1 , and an orthographic projection of the third connection region E on a plane of the main flexible printed circuit board  1  does not fall within the region range of the main flexible printed circuit board  1 ; and   the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  are connected through the first connection region C and the second connection region D, an orthographic projection of the third signal line  33  on the main flexible printed circuit board  1  has an overlapping region F with the second signal line, and in the overlapping region F, an electromagnetic shielding structure  4  is at least disposed at a side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2  or at a side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 .       

     In some embodiments, outlines of the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  are different, the orthographic projection of the second connection region D on the main flexible printed circuit board  1  completely falls within the region range of the main flexible printed circuit board  1 , the orthographic projection of the third connection region E on a plane of the main flexible printed circuit board  1  does not fall within the region range of the main flexible printed circuit board  1 . As shown in  FIG.  3   , the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  are rectangles of different sizes, a width of the outline of the main flexible printed circuit board  1  is greater than a width of the outline of the adaptor flexible printed circuit board  2 , and a length of the outline of the adaptor flexible printed circuit board  2  is smaller than a length of the outline of the main flexible printed circuit board  1 . 
     In the flexible printed circuit board, the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  may be of the following four structures; a first structure with the main flexible printed circuit board  1  being a single-layer board and the adaptor flexible printed circuit board  2  being a single-layer board, a second setting structure with the main flexible printed circuit board  1  being a single-layer board and the adaptor flexible printed circuit board  2  being a double-layer board, a third setting structure with the main flexible printed circuit board  1  being a double-layer board and the adaptor flexible printed circuit board  2  being a single-layer board, and a fourth setting structure with the main flexible printed circuit board  1  being a double-layer board and the adaptor flexible printed circuit board  2  being a double-layer board. In practical applications. The flexible printed circuit boards with the same layout sizes, regardless of single-layer or double-layer, are simpler in manufacturing process and lower in manufacturing cost compared with the multilayer board. 
     In the embodiment of the disclosure, the main flexible printed circuit board  1  includes a bonding region A configured for bonding with a display panel, a component arranging region B configured for arranging a control component, a first connection region C configured for connecting with the adaptor flexible printed circuit board  2 , and a signal line. The signal line includes a first signal line  31  disposed between the component arranging region B and the first connection region C, and a second signal line  32  disposed between the component arranging region B and the bonding region A. In some embodiments, the control component may be one or more. For example, the control component may be a touch driving chip, and a capacitor, a resistance and the like electrically connected with the touch driving chip, and the control component may further be a display driving chip, and a capacitor, a resistance and the like electrically connected with the display driving chip. As shown in  FIG.  3   , two component arranging regions B are set. 
     In some embodiments, the signal line may be a power line, a touch line, a display line and the like. The signal line includes the first signal line  31  disposed between the component arranging region B and the first connection region C, and a second signal line  32  disposed between the component arranging region B and the bonding region A. The first signal line  31  may be at least part of the power line, the touch line, the display line or the like, the second signal line  32  includes a first sub-line  321  and a second sub-line  322 , for example, the first sub-line  321  may be an Rx line, and the second sub-line  322  may be a Tx line. In practical applications, those skilled in the art may set each line on the main flexible printed circuit board  1  according to the specific situation of the quantity of board layers of the main flexible printed circuit board  1 , which will not be detailed here. 
     In the embodiment of the disclosure, the adaptor flexible printed circuit board  2  includes a second connection region D configured for connecting with the main flexible printed circuit board  1 , a third connection region E configured for connecting with a PCB, and a third signal line  33  disposed between the second connection region D and the third connection region E. In some embodiments, the third signal line  33  may be the power line and the display line. In practical applications, those skilled in the art may set each line on the adaptor flexible printed circuit board  2  according to the specific situation of the quantity of board layers of the adaptor flexible printed circuit board  2 , which will not be detailed here. 
     In the embodiment of the disclosure, the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  are connected through the first connection region C and the second connection region D respectively, so that the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  are lap-jointed together. 
     In the embodiment of the disclosure, in an overlapping region F of the second signal line  32  and the third signal line  33 , an electromagnetic shielding structure  4  is at least disposed on one side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , or at one side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 . In some embodiments, in the overlapping region F of the second signal line  32  and the third signal line  33 , the electromagnetic shielding structure  4  may be set as follows: the electromagnetic shielding structure  4  is disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , or the electromagnetic shielding structure  4  is disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 , or the electromagnetic shielding structure  4  is disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2  and the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 . In practical applications, the electromagnetic shielding structure  4  is set according to the board layer of the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2 , and the specific settings will be detailed in the following contents. In addition, in some embodiments, the electromagnetic shielding structure  4  may be set according to the needs of the actual effect of shielding, which is not limited here. 
     In the embodiment of the disclosure, in the overlapping region F of the second signal line  32  and the third signal line  33 , the electromagnetic shielding structure  4  is at least disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2  or on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 , so as to ensure that there is no signal interference between the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  which are lap-jointed. Since the main flexible printed circuit board  1  on the flexible printed circuit board may be manufactured by a single-layer board or a double-layer board, the adaptor flexible printed circuit board  2  may also be manufactured by the single-layer board or the double-layer board, the existing process may be adopted to manufacture, so that the manufacturing process of the flexible printed circuit board is simplified, and the manufacturing cost is reduced. 
     In the embodiment of the disclosure, the main flexible printed circuit board  1  in the flexible printed circuit board may be the double-layer board, as shown in  FIG.  6   , which is a schematic sectional view of the main flexible printed circuit board  1  along the direction indicated by MM′ in  FIG.  3   . Specifically, the main flexible printed circuit board  1  includes a first substrate layer  5 , a first conductive layer  6  disposed on a first surface of the first substrate layer  5 , and a second conductive layer  7  disposed on a second surface of the first substrate layer  5  opposite to the first surface. The first surface is one face of the first substrate layer  5  close to the adaptor flexible printed circuit board  2 , the first conductive layer  6  includes the first signal line  31 , and the second conductive layer  7  includes the second signal line  32 . In the overlapping region F, the electromagnetic shielding structure  4  includes a first conductive part  61  disposed on the first conductive layer  6 , the first conductive part  61  is insulated from the first signal line  31 , and the first conductive part  61  is grounded. As shown in  FIG.  7   , which is a schematic structural diagram of wiring of a first layer of the main flexible printed circuit board  1  shown in  FIG.  6   , and  FIG.  8    which is a schematic structural diagram of wiring of a second layer of the main flexible printed circuit board  1  shown in  FIG.  6   . 
     In some embodiments, materials of the first conductive layer  6  and the second conductive layer  7  are generally copper foils, the copper foils are etched according to the layout of the lines, one part of the copper foils forms the required signal lines, and the other part is grounded. In the overlapping region F, the electromagnetic shielding structure  4  includes the first conductive part  61  in the first conductive layer  6 , the first conductive part  61  is insulated from the first signal line  31 , and the first conductive part  61  is grounded. In some embodiments, in the overlapping region F, the first conductive part  61  is grounded, thereby realizing the shielding between the first signal line  31  and the second signal line  32  in the overlapping region F, and thus the performance of the flexible printed circuit board is improved. As shown in  FIG.  9   , which is a schematic top view of a first surface of the main flexible printed circuit board  1  in  FIG.  6   , a region indicated by a dotted line frame is the overlapping region F, and the first conductive part  61  is positioned in the overlapping region F. In some embodiments, since the main flexible printed circuit board  1  is the double-layer board, the existing process may be adopted to manufacture, and correspondingly, the manufacturing process is relatively simple. 
     In the embodiment of the disclosure, the adaptor flexible printed circuit board  2  in the flexible printed circuit board may be a single-layer board, as shown in  FIG.  10   , which is a schematic sectional view of the adaptor flexible printed circuit board  2  along the direction indicated by MM′ in  FIG.  3   . In some embodiments, the adaptor flexible printed circuit board  2  includes a second substrate layer  8 , and a third conductive layer  9  disposed on a third surface of the second substrate layer  8 . The third surface is one face of the second substrate layer  8  facing away from the main flexible printed circuit board  1 , the third conductive layer  9  includes a third signal line  33 , and the third signal line  33  is electrically connected with the first signal line  31  through a via hole running through the third conductive layer  9  and the second substrate layer  8 . 
     In some embodiments, a material of the third conductive layer  9  is generally a copper foil, the copper foil is etched according to the layout of the lines, so as to form the third signal line  33 . In some embodiments, when the adaptor flexible printed circuit board  2  is the single-layer board as shown in  FIG.  10   , and the main flexible printed circuit board  1  is the double-layer board as shown in  FIG.  6   , the electromagnetic shielding structure  4  may be the first conductive part  61  disposed on the main flexible printed circuit board  1 , the third signal line  33  is electrically connected with the first signal line  31  through the via hole running through the third conductive layer  9  and the second substrate layer  8 , thereby realizing the electric connection between the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2 . In some embodiments, the adaptor flexible printed circuit board  2  is the single-layer board, the existing process may be adopted to manufacture, and correspondingly, the manufacturing process is relatively simple. 
     In the embodiment of the disclosure, the adaptor flexible printed circuit board  2  in the flexible printed circuit board may be the double-layer board, as shown in  FIG.  11   , which is a schematic sectional view of the adaptor flexible printed circuit board  2  along the direction indicated by MM′ in  FIG.  3   . In some embodiments, the adaptor flexible printed circuit board  2  includes a third substrate layer  10 , a fourth conductive layer  20  disposed on a fourth surface of the third substrate layer  10 , and a fifth conductive layer  30  disposed on a fifth surface of the third substrate layer  10  opposite to the fourth surface. The fifth surface is one face of the third substrate layer  10  close to the main flexible printed circuit board  1 , and the fourth conductive layer  20  includes the third signal line  33 ; and in the overlapping region F, the electromagnetic shielding structure  4  includes a second conductive part  301  in the fifth conductive layer  30 , and the second conductive part  301  is grounded. 
     In some embodiments, materials of the fourth conductive layer  20  and the fifth conductive layer  30  are generally copper foils, the copper foils are etched according to the layout of the lines, one part of the copper foils forms the required signal lines, and the other part may be grounded according to the needs. In the overlapping region F, the electromagnetic shielding structure  4  includes the second conductive part  301  in the fifth conductive layer  30 , and the second conductive part  301  is grounded. In some embodiments, in the overlapping region F, the second conductive part  301  is grounded, thereby realizing the shielding between the first signal line  31  and the second signal line  32  in the overlapping region F, and thus the performance of the flexible printed circuit board is improved. In some embodiments, since the main flexible printed circuit board  1  is the double-layer board, the existing process may be adopted to manufacture, and correspondingly, the manufacturing process is relatively simple. 
     In some embodiments, when the adaptor flexible printed circuit board  2  is the double-layer board as shown in  FIG.  11   , and the main flexible printed circuit board  1  is the single-layer board as shown in  FIG.  6   , the electromagnetic shielding structure  4  may include the first conductive part  61  in the main flexible printed circuit board  1 , and the second conductive part  301  in the adaptor flexible printed circuit board  2 , the first conductive part  61  and the second conductive part  301  are grounded, thereby realizing the shielding between the first signal line  31  and the second signal line  32  in the overlapping region F. Since there are two layers of grounded conductive parts between the first signal line  31  and the second signal line  32 , the shielding between the first signal line  31  and the second signal line  32  is improved, and thus the performance of the flexible printed circuit board is improved. In addition, in some embodiments, when the adaptor flexible printed circuit board  2  is the double-layer board as shown in  FIG.  11   , and the main flexible printed circuit board  1  is the double-layer board as shown in  FIG.  6   , the third signal line  33  is electrically connected with the first signal line  31  through a via hole running through the fifth conductive layer  30  and the third substrate layer  10 , thereby realizing the electric connection between the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2 . In some embodiments, the adaptor flexible printed circuit board  2  is the double-layer board, the existing process may be adopted to manufacture, and correspondingly, the manufacturing process is relatively simple. 
     In the embodiment of the disclosure, the main flexible printed circuit board  1  in the flexible printed circuit board may be the single-layer board, as shown in  FIG.  12   , which is a schematic sectional view of the main flexible printed circuit board  1  along the direction indicated by MM′ in  FIG.  3   . In some embodiments, the main flexible printed circuit board  1  includes a fourth substrate layer  302 , and a sixth conductive layer  303  disposed on a fourth surface of the fourth substrate layer  302 . The fourth surface is one face of the fourth substrate layer  302  facing away from the adaptor flexible printed circuit board  2 , and the sixth conductive layer  303  includes the first signal line  31  and the second signal line  32 . In some embodiments, a material of the sixth conductive layer  303  is generally a copper foil, the copper foil is etched according to the layout of the lines, so as to form the first signal line  31  and the second signal line  32 . 
     In some embodiments, when the adaptor flexible printed circuit board  2  is the single-layer board as shown in  FIG.  10   , and the main flexible printed circuit board  1  is the single-layer board as shown in  FIG.  12   , the electromagnetic shielding structure  4  may be disposed at one side of the fourth substrate layer  302  close to the adaptor flexible printed circuit board  2 , and the electromagnetic shielding structure  4  may further be disposed at one side of the second substrate layer  8  close to the main flexible printed circuit board  1 . When the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  in the flexible printed circuit board are both the single-layer boards, the manufacturing process of the flexible printed circuit board is simplified, and meanwhile, the lightweight design of the flexible printed circuit board is realized. 
     In some embodiments, when the adaptor flexible printed circuit board  2  is the double-layer board as shown in  FIG.  11   , and the main flexible printed circuit board  1  is the single-layer board as shown in  FIG.  12   , the electromagnetic shielding structure  4  may be disposed at the side of the fourth substrate layer  302  close to the adaptor flexible printed circuit board  2 , and the electromagnetic shielding structure  4  may further be disposed in the fifth conductive layer  30 , such as the second conductive part  301 . 
     In the embodiment of the disclosure, in combination with  FIG.  13    and  FIG.  14   , in the overlapping region F, the electromagnetic shielding structure  4  includes a first electromagnetic shielding layer  40  disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , and/or a second electromagnetic shielding layer  50  disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 . In a specific embodiment, in the overlapping region F, based on the flexible printed circuit board shown in  FIG.  3   , whether the main flexible printed circuit board  1  is the single-layer board or the double-layer board, and the adaptor flexible printed circuit board  2  is the single-layer board or the double-layer board, the first electromagnetic shielding layer  40  may be directly disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , or the second electromagnetic shielding layer  50  may be directly disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 ; or the first electromagnetic shielding layer  40  may be directly disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , and the second electromagnetic shielding layer  50  may be directly disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 , thereby improving a shielding effect between the second signal line  32  and the third signal line  33  in the overlapping region F, and thus the use performance of the flexible printed circuit board is improved. In addition, since the first electromagnetic shielding layer  40  and the second electromagnetic shielding layer  50  may be directly attached to corresponding positions according to the needs, the whole manufacturing process is relatively simple, and the manufacturing cost is low. 
     In some embodiments, when the main flexible printed circuit board  1  is the double-layer board shown in  FIG.  6   , in the overlapping region F, the first electromagnetic shielding layer  40  may be disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , specifically may be disposed on one side of the first conductive part  61  facing the adaptor flexible printed circuit board  2 . Since the first conductive part  61  and the first electromagnetic shielding layer  40  are disposed on the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2  at the same time, the shielding effect between the third signal line  33  and the second signal line  32  in the overlapping region F is improved, and thus the use performance of the flexible printed circuit board is improved. 
     In some embodiments, when the adaptor flexible printed circuit board  2  is the single-layer board shown in  FIG.  10   , in the overlapping region F, the second electromagnetic shielding layer  50  may be disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 , since the second electromagnetic shielding layer  50  is disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 , the shielding between the third signal line  33  and the second signal line  32  in the overlapping region F is ensured, and thus the use performance of the flexible printed circuit board is improved. 
     In addition, when the main flexible printed circuit board  1  is the double-layer board shown in  FIG.  6   , and the adaptor flexible printed circuit board  2  is the single-layer board shown in  FIG.  10   , if the first electromagnetic shielding layer  40  is disposed on the side of the first conductive part  61  facing the adaptor flexible printed circuit board  2 , and the second electromagnetic shielding layer  50  is disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1  at the same time, the shielding effect between the third signal line  33  and the second signal line  32  is enhanced under the shielding action of the first conductive part  61 , the first electromagnetic shielding layer  40  and the second electromagnetic shielding layer  50 , and the performance of the flexible printed circuit board is improved. 
     In some embodiments, when the adaptor flexible printed circuit board is the double-layer board shown in  FIG.  11   , in the overlapping region F, the second electromagnetic shielding layer  50  may be disposed on the side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 , specifically may be disposed on one side of the second conductive part  301  facing the main flexible printed circuit board  1 , thereby ensuring the shielding between the third signal line  33  and the second signal line  32  in the overlapping region F, and thus the use performance of the flexible printed circuit board is improved. 
     In addition, when the main flexible printed circuit board  1  is the double-layer board shown in  FIG.  6   , and the adaptor flexible printed circuit board  2  is the double-layer board shown in  FIG.  11   , if the first electromagnetic shielding layer  40  is disposed on the side of the first conductive part  61  facing the adaptor flexible printed circuit board  2 , and the second electromagnetic shielding layer  50  is disposed on the side of the second conductive part  301  facing the main flexible printed circuit board  1  at the same time, the shielding effect between the third signal line  33  and the second signal line  32  is enhanced under the shielding action of the first conductive part  61 , the first electromagnetic shielding layer  40 , the second conductive part  301  and the second electromagnetic shielding layer  50 , and the performance of the flexible printed circuit board is improved. 
     In the embodiment of the disclosure, for a specific example, when the main flexible printed circuit board  1  in the flexible printed circuit board is the single-layer board shown in 
       FIG.  12   , and the adaptor flexible printed circuit board  2  is the single-layer board shown in  FIG.  10   , as shown in  FIG.  13   , which is a schematic sectional view in the direction shown by MM′ in  FIG.  3   . In some embodiments, the first electromagnetic shielding layer  40  is disposed at one side of the fourth substrate layer  302  of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , and the second electromagnetic shielding layer  50  is disposed at one side of the second substrate layer  8  of the adaptor flexible printed circuit board  2  close to the main flexible printed circuit board  1 . Of course, those skilled in the art may further set the positions of the first electromagnetic shielding layer  40  and the second electromagnetic shielding layer  50  according to the actual needs, which will not be detailed here. 
     In the embodiment of the disclosure, for a specific example, when the main flexible printed circuit board  1  in the flexible printed circuit board is the double-layer board shown in  FIG.  6   , and the adaptor flexible printed circuit board  2  is the single-layer board shown in  FIG.  10   , as shown in  FIG.  14   , which is a schematic sectional view in the direction shown by MM′ in  FIG.  3   . In some embodiments, the grounded first conductive part  61  is disposed in the first conductive layer  6  of the main flexible printed circuit board  1 , the first electromagnetic shielding layer  40  is disposed at one side of the first conductive part  61  close to the adaptor flexible printed circuit board  2 , and the second electromagnetic shielding layer  50  is disposed at the side of the second substrate layer  8  of the adaptor flexible printed circuit board  2  close to the main flexible printed circuit board  1 . Of course, those skilled in the art further set the positions of the first electromagnetic shielding layer  40  and the second electromagnetic shielding layer  50  according to the actual needs, which will not be detailed here. 
     In the embodiment of the disclosure, a first covering film  60  is disposed at the side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2 , and the first electromagnetic shielding layer  40  is disposed on one side of the first covering film  60  close to the adaptor flexible printed circuit board  2 . The first covering film  60  can ensure that the first conductive layer  6  is not exposed to the air, which avoids the oxidation of the first conductive layer  6 , and thus the performance of the flexible printed circuit board is improved. As shown in  FIG.  15   , which is a schematic sectional view of the main flexible printed circuit board  1  in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    of the embodiment of the disclosure. 
     Of course, in practical applications, in addition to the above setting modes of the electromagnetic shielding structure  4 , those skilled in the art may further set the electromagnetic shielding structure  4  according to the actual needs, which will not be detailed here. 
     In the embodiment of the disclosure, the first electromagnetic shielding layer  40  is one or more of conductive rubber, conductive cloth, conductive foam or conductive shielding glue, and the second electromagnetic shielding layer  50  is one or more of the conductive rubber, the conductive cloth, the conductive foam or the conductive shielding glue. While the first electromagnetic shielding layer  40  and the second electromagnetic shielding layer  50  effectively shield the third signal line  33  and the second signal line  32 , the whole manufacturing process is relatively simple. 
     In the embodiment of the disclosure, the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  are connected together in the first connection region C and the second connection region D respectively through a board-to-board (BTB) connector, a zero-insertion-force (ZIF) connector and FOF bonding, so that the effective electric connection between the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  is ensured, and the connection flexibility between the two can be ensured. In addition, in some embodiments, a contact pad connection mode of soldering tin may further be used to realize the connection between the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  in the first connection region C and the second connection region D respectively. Of course, in addition, other types of connectors may be selected according to the actual needs to realize the electric connection between the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  in the first connection region C and the second connection region D, which is not limited here. 
     In the embodiment of the disclosure, a second covering film  70  is disposed on one side of the second conductive layer  7  facing away from the first substrate layer  5 . The second covering film  70  can avoid the second conductive layer  7  from being exposed to the air, which avoids the oxidation of the second conductive layer  7 , and thus the performance of the flexible printed circuit board is improved. As shown in  FIG.  16   , which is a schematic structural diagram of the main flexible printed circuit board  1  in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    of the embodiment of the disclosure. 
     In the embodiment of the disclosure, a third covering film  80  is disposed on one side of the third conductive layer  9  facing away from the second substrate layer  8 . The third covering film  80  can avoid the third conductive layer  9  from being exposed to the air, which avoids the oxidation of the third conductive layer  9 , and thus the performance of the flexible printed circuit board is improved. In  FIG.  17   , a schematic structural diagram of the adaptor flexible printed circuit board  2  in the flexible printed circuit board along the direction indicated by MM′ in  FIG.  3    of the embodiment of the disclosure is shown. 
     In some embodiments, taking a display panel as an example, as shown in  FIG.  18   , which is a schematic sectional view of the main flexible printed circuit board  1  along the direction indicated by NN′ in  FIG.  3   , a line positioned in the bonding region A may be led out from the second conductive layer  7  of the main flexible printed circuit board  1 . In this case, the power line and the display line positioned on the main flexible printed circuit board  1  extend to the first conductive layer  6  through a via hole before being connected with the adaptor flexible printed circuit board  2 , the Tx line and the Rx line related to a touch function are connected with a touch driving component  03  on the first conductive layer  6 , and except for the Tx line, the Rx line, the power line and the display line, the rest of the lines may be in the first conductive layer  6  or the second conductive layer  7 . In the overlapping region F, the Tx line and the Rx line on the main flexible printed circuit board  1  are in the second conductive layer  7 , thereby ensuring that the flexible printed circuit board has a good shielding effect, and thus the use performance of the flexible printed circuit board is improved. 
     In addition, in some embodiments, as shown in  FIG.  19   , which is a schematic sectional view of the main flexible printed circuit board  1  along the direction indicated by NN′ in  FIG.  3   , a line positioned in the bonding region A may also be led out from the first conductive layer  6  of the main flexible printed circuit board  1 , and the introduction of the relevant film layers is the same as above, which will not be detailed here. 
     In the embodiment of the disclosure, thicknesses of the first substrate layer  5 , the second substrate layer  8 , the third substrate layer  10 , the first conductive layer  6 , the second conductive layer  7 , the third conductive layer  9 , the fourth conductive layer  20 , the fifth conductive layer  30 , the first covering film  60 , the second covering film  70  and the third covering film  80  are not specifically limited. 
     In some embodiments, the above flexible printed circuit board provided by the embodiment of the disclosure further includes other film layers, such as a glue layer, a reinforcement layer, etc., which are the same as those in the related art, and will not be detailed here. 
     In the embodiment of the disclosure, for the flexible printed circuit board of the multilayer boards, especially for a special-shaped structure such as that shown in  FIG.  1   , in the related art, a plurality of flexible printed circuit boards shown in  FIG.  1    are usually laid on a single layout, and then cut into required flexible printed circuit boards. Taking the layout shown in  FIG.  20    as an example, only six flexible printed circuit boards shown in  FIG.  1    can be arranged on the same layout. If the layout of the same size is adopted to manufacture the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  in the embodiment of the disclosure, the main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  may be manufactured separately, and then the two are connected together to form a special-shaped flexible printed circuit board. When the layout of the same size as that is  FIG.  20    is adopted, the schematic layout diagram of the flexible printed circuit board provided by the embodiment of the disclosure is as shown in  FIG.  21   , as an example, eleven main flexible printed circuit boards  1  and eleven adaptor flexible printed circuit boards  2  can be arranged on the layout respectively, and eleven flexible printed circuit boards can be manufactured after cutting. It can be seen that the manufacturing efficiency of the flexible printed circuit board in the embodiment of the disclosure is higher. 
     Based on the same inventive concept, an embodiment of the disclosure further provides a display apparatus, as shown in  FIG.  22   , which is a schematic decomposition diagram of the display apparatus, specifically, the display apparatus includes: a display panel  100 , and a flexible printed circuit board  200  electrically connected with the display panel  100 . 
     The flexible printed circuit board  200  includes: a main flexible printed circuit board  1  and an adaptor flexible printed circuit board  2  with an outline different from the main flexible printed circuit board  1 , the main flexible printed circuit board  1  is a single-layer board or double-layer board, and the adaptor flexible printed circuit board  2  is a single-layer board or double-layer board. 
     The main flexible printed circuit board  1  includes a bonding region A configured for bonding with the display panel  100 , a component arranging region B configured for arranging a control component, a first connection region C configured for connecting with the adaptor flexible printed circuit board  2 , and a signal line  3 , and the signal line  3  includes a first signal line  31  disposed between the component arranging region B and the first connection region C, and a second signal line  32  disposed between the bonding region A and the component arranging region B. 
     The adaptor flexible printed circuit board  2  includes a second connection region D configured for connecting with the main flexible printed circuit board  1 , a third connection region E configured for connecting with a PCB, and a third signal line  33  disposed between the second connection region D and the third connection region E. An orthographic projection of the second connection region D on the main flexible printed circuit board  1  completely falls within a region range of the main flexible printed circuit board  1 , and an orthographic projection of the third connection region E on a plane of the main flexible printed circuit board  1  does not fall within the region range of the main flexible printed circuit board  1 . 
     The main flexible printed circuit board  1  and the adaptor flexible printed circuit board  2  are connected together through the first connection region C and the second connection region D, and an orthographic projection of the third signal line  33  on the main flexible printed circuit board  1  overlaps with the second signal line; and in an overlapping region F of the second signal line  32  and the third signal line  33 , an electromagnetic shielding structure  4  is at least disposed at one side of the main flexible printed circuit board  1  facing the adaptor flexible printed circuit board  2  or at one side of the adaptor flexible printed circuit board  2  facing the main flexible printed circuit board  1 . 
     In some embodiments, the display panel  100  includes: pixel units PX arranged in an array, and a first functional line  101  electrically connected with the pixel units PX. The first functional line  101  is electrically connected with the third signal line  33  on the flexible printed circuit board  200  through the bonding region A, and the first functional line  101  is configured to receive a display signal from the flexible printed circuit board  200 . 
     The display panel  100  further includes a touch layer  300 , the touch layer  300  is disposed at one sides of the pixel units PX away from a base substrate, and has a plurality of first touch electrodes  901  and a plurality of second touch electrodes  902 . A second functional line  102  is electrically connected with the first touch electrodes  901 , a third functional line  103  is electrically connected with the second touch electrodes  902 , the second functional line  102  is electrically connected with a first sub-line  321  in the second signal line  32  on the flexible printed circuit board  200  through the bonding region A, the third functional line  103  is electrically connected with a second sub-line  322  in the second signal line  32  on the flexible printed circuit board  200  through the bonding region A, and the second functional line  102  and the third functional line  103  are configured to receive or send a touch signal. 
     In some embodiments, the first sub-line  321  may be an Rx line on the flexible printed circuit board  200 , and the second sub-line  322  may be a Tx line on the flexible printed circuit board  200 . The first functional line  101  may be a Data line, a VDD line or a VSS line, which is not limited here. The second functional line  102  may be an Rx line on the display panel  100 , and the third functional line  103  may be a Tx line on the display panel  100 . 
     In some embodiments, the first touch electrodes  901  and the second touch electrodes  902  are disposed in the same layer, correspondingly forming a self-capacitive touch, and the first touch electrodes  901  and the second touch electrodes  902  may be self-capacitive electrodes. Mutual capacitive electrodes may be selected according to the actual needs, and the specific settings are the same as those of the related art, which will not be detailed here. 
     In some embodiments, the display apparatus further includes a functional module layer  400  and a cover plate  500  which are disposed at one side of the touch layer  300  facing away from the base substrate. The functional module layer  400 , may be a polarizer, of course, may be set to include other film layers according to the actual needs, which will not be detailed here. 
     In some embodiments, the principle for solving problems of the display apparatus is similar to that of the above flexible printed circuit board  200 , therefore, the implementation of the display apparatus may refer to the implementation of the above flexible printed circuit board  200 , and repetition will not be made. 
     In some embodiments, the flexible printed circuit board  200  may be bent to a back of the display panel, so as to realize a narrow bezel design of the display apparatus. The display apparatus provided by the embodiment of the disclosure may be a mobile phone, a tablet computer, a television, a display, a laptop, a digital photo frame, a navigator and any product or component with a display function. Other essential components of the display apparatus shall be understood by those of ordinary skill in the art, and is omitted herein and also shall not become a restriction to the disclosure. 
     Although the preferred embodiments of the disclosure have been described, those skilled in the art can make additional changes and modifications on these embodiments once they know the basic creative concept. So the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications that fall into the scope of the disclosure. 
     Obviously, those skilled in the art can make various modifications and variations to the disclosure without departing from the spirit and scope of the disclosure. In this way, if these modifications and variations of the disclosure fall within the scope of the claims of the disclosure and equivalent technologies thereof, the disclosure is also intended to include these modifications and variations.