Patent Publication Number: US-2021183980-A1

Title: Display panel and bonding method of the same

Description:
BACKGROUND OF THE INVENTION 
     Field of Invention 
     The present invention relates to the field of display panel manufacturing technology, and particularly to a display panel and a bonding method of the display panel. 
     Description of Prior Art 
     The mobile phone using environment is diversified, and some high-humidity and high-temperature environments are more corrosive to the screen of the mobile phone, so the requirement for corrosion resistance of the screen is increasingly higher. The main concern for waterproof and anti-corrosion of the module segment lies in the lines of the wire on array (WOA) of the bonding area between the chip on film (COF) and the display panel. The anti-corrosion method for the WOA lines according to the traditional LCD fabrication process is to apply anti-corrosion coating on the front side of the WOA lines and the back side of the bonding area of the COF and the WOA. 
     Referring to  FIGS. 1A-1B , after the WOA lines  104  connected to the internal signal line of the display panel  101  formed in the non-display area of the display panel  101  and the flexible circuit board  103  are bonded together by the conductive adhesive  102 , an exposed portion of the WOA lines  104  corresponding to outside of the conductive adhesive  102  and an exposed portion of the COF lines  105  of the flexible circuit board  103  for bonding corresponding to outside of the conductive adhesive  102  are highly susceptible to be corroded. The existing countermeasure is to apply a layer of waterproof glue in the corrosive area to isolate air and moisture and achieve anti-corrosion requirements. As shown in  FIG. 1B , the exposed portion of the WOA lines  104  is covered by the front side waterproof adhesive  106 , and the exposed portion of the COF lines  105  is covered by the back surface waterproof adhesive  107 . In the OLED industry, since the glass substrate  108  needs to be stripped, there are two problems; one is that the back surface waterproof adhesive  107  and the glass substrate  108  are adhered, which is not conducive for the stripping operation; the second is that the height of the back surface waterproof adhesive  107  exceeds the OLED layer  109  after the glass substrate  108  is stripped, which affects the subsequent process, and this problem cannot be effectively solved by the current industry. The present solution is to have the back side not coated with the waterproof glue  107 . Such a solution has a risk for the quality in the long-term. 
     Therefore, it is necessary to provide a display panel and a bonding method of the display panel to solve the problems existing in the prior art. 
     SUMMARY OF THE INVENTION 
     The application mainly provides a display panel and a bonding method of the display panel to avoid signal lines to be corroded without forming a back surface waterproof adhesive and improve product quality and stability. 
     For the above-mentioned objective, the present disclosure employs the following technical schemes. 
     The present disclosure provides a display panel, the display panel includes a display area and a non-display area formed at a side of the display area, at least two signal lines are arranged in the non-display area, a bonding area is defined in the non-display area, ends of one side of the signal lines extend to the bonding area; 
     an overlapping area and a non-overlapping area are defined in the non-display area and the bonding area, a first area is defined in the non-overlapping area formed at a side of the bonding area, a second area is defined in the non-overlapping area formed at another, opposite side of the bonding area; and 
     a waterproof adhesive layer is formed in the first region, a conductive adhesive layer is formed in the bonding area; the conductive adhesive layer includes a conductive-particles doped region and a first insulating rubber material region formed at one side of the conductive-particles doped region, the first insulating rubber material region is formed between the conductive-particles doped region and the second area. 
     In the display panel of the present disclosure, a second insulating rubber material region is formed at another, opposite side of the conductive-particles doped region, the second insulating rubber material region extends toward the first area and ends at one side edge of the bonding area, the first insulating rubber region extends toward the second area and ends at another, opposite side edge of the bonding area. 
     In the display panel of the present disclosure, the waterproof adhesive layer and the conductive adhesive layer are formed on the signal lines. 
     In the display panel of the present disclosure, a flexible circuit board is connected with the display panel, a plurality of connection terminals is formed on the flexible circuit board, and the connection terminals are correspondingly located in the bonding area. 
     In the display panel of the present disclosure, the waterproof rubber layer extends at least to one side surface of the flexible circuit board. 
     The present disclosure provides a bonding method of a display panel, the bonding method includes: 
     a step S 10  of providing a display panel, defining a display area, a non-display area formed at a side of the display area, and a bonding area in the non-display area are defined in the display panel surface; defining an overlapping area and a non-overlapping area in the non-display area and the bonding area, defining a first area in the non-overlapping area formed at a side of the bonding area, defining a second area in the non-overlapping area formed at another, opposite side of the bonding area; 
     a step S 20  of forming a conductive adhesive layer on the bonding area; 
     a step S 30  of adhering ends of a plurality of connection terminals of the flexible circuit board to the conductive adhesive layer, and then bonding the flexible circuit board and the bonding area together by a heat pressing device; and 
     the conductive adhesive layer comprises a conductive-particles doped region and a first insulating rubber material region formed at one side of the conductive-particles doped region, the first insulating rubber material region is formed between the conductive-particles doped region and the second area. 
     In the bonding method of the display panel of the present disclosure, the conductive adhesive layer further includes a second insulating rubber material region formed at another, opposite side of the conductive-particles doped region, and the second insulating rubber material region extends toward the first area and ends at one side edge of the bonding area. 
     In the bonding method of the display panel of the present disclosure, the connection terminals formed on the flexible circuit board are correspondingly located in the bonding area. 
     In the bonding method of the display panel of the present disclosure, the step S 30  further including: 
     a step S 40  of forming a waterproof rubber layer in the first region to forming a sealant layer combined by the waterproof rubber layer and the conductive adhesive layer in the non-display region. 
     The present disclosure provides a display panel, the display panel includes a display area and a non-display area formed at a side of the display area, at least two signal lines are arranged in the non-display area, a bonding area is defined in the non-display area, ends of one side of the signal lines extend to the bonding area; 
     a plurality of thin film transistors are formed in the display area, ends of another, opposite side of the signal lines are correspondingly connected to the thin film transistors; 
     an overlapping area and a non-overlapping area are defined in the non-display area and the bonding area, a first area is defined in the non-overlapping area formed at a side of the bonding area, a second area is defined in the non-overlapping area formed at another, opposite side of the bonding area; and 
     a waterproof adhesive layer is formed in the first region, a conductive adhesive layer is formed in the bonding area; the conductive adhesive layer includes a conductive-particles doped region and a first insulating rubber material region formed at one side of the conductive-particles doped region, the first insulating rubber material region is formed between the conductive-particles doped region and the second area. 
     In the display panel of the present disclosure, a second insulating rubber material region is formed at another, opposite side of the conductive-particles doped region, the second insulating rubber material region extends toward the first area and ends at a side edge of the bonding area, the first insulating rubber region extends toward the second area and ends at another, opposite side edge of the bonding area. 
     In the display panel of the present disclosure, the waterproof adhesive layer and the conductive adhesive layer are formed on the signal lines. 
     In the display panel of the present disclosure, a flexible circuit board is connected with the display panel, a plurality of connection terminals is formed on the flexible circuit board, and the connection terminals are correspondingly located in the bonding area. 
     In the display panel of the present disclosure, the waterproof rubber layer extends at least to one side surface of the flexible circuit board. 
     The beneficial effect of this invention is: in a display panel and a bonding method of the display panel of the present disclosure, among a COF bonding process, an insulating rubber material layer are is formed at one side or two sides of the conductive-particles doped region of the conductive adhesive layer to increase a width of the conductive adhesive layer, a front waterproof adhesive layer covers signal lines of a display area to form a sealed waterproofing area and to solve a corrosion risk of a back surface of OLED products without the waterproof adhesive layer after a COF bonding process. The present disclosure makes the back surface of OLED products not to be coated by the waterproof adhesive layer and to separate a glass substrate from the flexible OLED products without effecting a continuing process; because the insulating rubber material layers formed at two sides of the conductive-particles doped region have a supporting function to make a same flowability in left and right sides of the conductive-particles doped region in a pressing process to promote a pressing accuracy and to avoid a decreasing accuracy problem caused by a decreasing size of the bonding area. The present disclosure can ensure that the conductive properties of the conductive-particles doped region are not affected, and also ensure that the signal lines of the non-display area are not in contact with the air to avoid the lines to be corroded, and to save the coating process, thereby to improve product quality and stability and to improve a corrosion resistance of the product&#39;s extreme use environment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures to be used in the description of embodiments of the present disclosure or prior art will be described in brief to more clearly illustrate the technical solutions of the embodiments or the prior art. The accompanying figures described below are only part of the embodiments of the present disclosure, from which figures those skilled in the art can derive further figures without making any inventive efforts. 
         FIGS. 1A-1B  are schematic views of a structure of the display panel in prior art. 
         FIG. 2A  is a schematic view of a structure of a display panel of one exemplary embodiment according to the present disclosure. 
         FIG. 2B  is a top view of the display panel of the exemplary embodiment according to the present disclosure. 
         FIG. 2C  is a side view of the display panel of the exemplary embodiment according to the present disclosure. 
         FIG. 3  is a schematic view of a display panel of another exemplary embodiment according to the present disclosure. 
         FIG. 4  is a flow chart of a bonding method of a display panel of one exemplary embodiment according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The description of following embodiment, with reference to the accompanying drawings, is used to exemplify specific embodiments which may be carried out in the present disclosure. Directional terms mentioned in the present disclosure, such as “top”, “bottom”, “front”, “back”, “left”, “right”, “inside”, “outside”, “side”, etc., are only used with reference to the orientation of the accompanying drawings. Therefore, the used directional terms are intended to illustrate, but not to limit, the present disclosure. In the drawings, the components having similar structures are denoted by same numerals. 
     The present disclosure is directed to a display panel of the prior art. Since a waterproof adhesive coated in a back surface of the a flexible circuit board bonding with signal lines of the display panel are adhered to a glass substrate, the peeling is unfavorable, and a height of the back surface waterproof adhesive after the glass substrate peeled off are over the OLED layer to affect of a subsequent process. The present disclosure can solve the above defects. 
     Referring to  FIGS. 2A-2C ,  FIG. 2A  is a schematic view of a structure of a display panel of one exemplary embodiment according to the present disclosure. Referring to  FIG. 2A , the display panel includes a display area  201  and a non-display area  202  formed at a side of the display area  201 . A plurality of signal lines is arranged in the non-display area  202 . A bonding area  203  is defined in the non-display area  202 . An overlapping area and a non-overlapping area are defined in the non-display area  202  and the bonding area  203 . A first area  205  is defined in the non-overlapping area and formed at a side of the bonding area  203 . A second area  204  is defined in the non-overlapping area and formed at another, opposite side of the bonding area. The bonding area  203  includes a conductive-particles doped region and an insulating rubber material region located at an end of the conductive-particles doped region away from the display area  201 . 
     The bonding area  203  can extend away from the display area  201  to an correspondingly edge of the display panel. However, in order to avoid the rubber material formed in the insulating rubber material area from overflowing to a side surface of the display panel to adversely affect a peeling process of the glass substrate, preferably, a space distance is defined between the bonding area  203  and the edge of the display panel. 
     Referring to  FIG. 2B ,  FIG. 2B  is a top view of the display panel of the exemplary embodiment according to the present disclosure. A plurality of the thin film transistors and a plurality of pixel units are formed in the display area  201 . Ends of one side of the signal lines  211  arranged in the non-display area are correspondingly connected to the thin film transistors. Ends of another, opposite side of the signal lines  211  arranged in the non-display area extend to the bonding area. A conductive adhesive layer  209  is formed in the bonding area. The conductive adhesive layer  209  includes a conductive-particles doped region  207  and a first insulating rubber material region  208  formed at one side of the conductive-particles doped region  207 . The first insulating rubber material region  208  is formed between the conductive-particles doped region  207  and the second area to cover the signal lines  211  exposed from one side of the conductive-particles doped region  207  away from the display area  201 . The flexible circuit board  210  is bonded to an edge of the display panel by the conductive adhesive layer  209 . A plurality of connection terminals is formed on the flexible circuit board  210 . The connection terminals are placed in the bonding area. The connection terminals are electrically connected to the signal lines  211  by the conductive-particles doped region  207 . After the flexible circuit board  210  is bonded with the display panel, a waterproof adhesive layer  206  is formed in the first area. The waterproof adhesive layer  206  and the conductive adhesive layer  209  totally cover the signal lines  211  and the connection terminals formed on the flexible circuit board  210  to form a hermetical structure around the signal lines  211  and the connection terminals, to avoid moisture from entering into its interior, to solve a problem of OLED products that after a COF bonding process there is no waterproof adhesive layer in the backside thereof, and to improve product quality and reliability. 
     Referring to  FIG. 2C ,  FIG. 2C  is a side view of the display panel of the exemplary embodiment according to the present disclosure. The display panel includes a glass substrate  212 , an OLED layer  213  formed on the glass substrate  212 , and a polarizer  214  formed on the OLED layer  213 . The flexible circuit board  210  is adhered to the conductive adhesive layer  209  and bonded with the display panel by a pressing process with a heat pressing device  215 . During the pressing process, the first insulating rubber material region  208  formed at one side of the conductive-particles doped region  207  extends toward the second area (an edge of the display panel to totally cover the signal lines of the conductive-particles doped region  207  near the edge of the display panel and a correspondingly part of the connection terminals. After the bonding process is finished, the waterproof adhesive layer  206  is formed in the first area defined between the conductive adhesive layer  209  and the polarizer  214 . 
     In one embodiment, a width of the conductive-particles doped region  207  is larger than a width of the first insulating rubber material region  208 . In one embodiment, the waterproof adhesive layer  206  at least extends to one side surface of the flexible circuit board  210 . 
     Referring to  FIG. 3 ,  FIG. 3  is a schematic view of a structure of a display panel of another exemplary embodiment according to the present disclosure. The embodiment is a preferable embodiment of the invention. The display panel includes a glass substrate  301 , an OLED layer  302  formed on the glass substrate  301 , and a polarizer. The display panel further includes a flexible circuit board  305  which is bonded to the display panel through a conductive adhesive layer  309 . Compared with  FIG. 2 , a distinguishing technique is: a second insulating rubber material region  308  is formed at another, opposite side of the conductive-particles doped region  307  of the conductive adhesive layer  309 . The first insulating rubber material region  306  extends toward the second area and ends at an edge of the bonding area. The second insulating rubber material region  308  extends toward the first area and ends at another edge of the bonding area. After an end surface of the flexible circuit board  305  with the connection terminals is adhered to the conductive adhesive layer  309 , a pressing process is applied by a heat pressing device  304 . By the support of the rubber material of the first insulating rubber material region  306  and the second insulating rubber material region  308 , a same flowability of the conductive-particles doped region  307  regarding left and right sides thereof, an accuracy for the pressing operation can be promoted. The rubber material of the conductive-particles doped region  307  can be different from the rubber material of the first insulating rubber material region  306  and the second insulating rubber material region  308 , and the two rubber materials has a low degree permeation to avoid the rubber material of the conductive-particles doped region  307  from permeating into the rubber material of the first insulating rubber material region  306  and the second insulating rubber material region  308  during the pressing process and to avoid an inferior pressing accuracy. In one embodiment, a width of the first insulating rubber material region  306  is same as a width of the second insulating rubber material region  308 . The conductive adhesive layer  309  and the waterproof adhesive layer  310  cover the signal lines of the non-display area and the connection terminals to achieve an anti-corrosion effect. Because a back surface does not need a waterproof adhesive layer thereon, the glass substrate  301  can be easily peeled from the OLED layer  302  in a subsequent process. 
     The present disclosure further provides a bonding method of the display panel. Referring to  FIG. 4 , the method includes: 
     S 10 : a display panel is provided; a surface of the display panel is defined with a display area, a non-display area formed at a side of the display area and a bonding area defined in the non-display area; an overlapping area and a non-overlapping area are defined in the non-display area and the bonding area; a first area is defined in the non-overlapping area and formed at a side of the bonding area; and a second area is defined in the non-overlapping area and formed at another, opposite side of the bonding area. 
     A plurality of signal lines is arranged in the non-display area. A bonding area is defined in the non-display area. A plurality of thin film transistors is formed in the bonding area. Ends of a side of the signal lines extend to the bonding area, and ends of another, opposite side of the signal lines are correspondingly connected to the thin film transistors. 
     S 20 : a conductive adhesive layer is formed on the bonding area. 
     The conductive adhesive layer includes a conductive-particles doped region and a first insulating rubber material region formed at one side of the conductive-particle doped region. The first insulating rubber material region is formed between the conductive-particle doped region and the second area 
     S 30 : ends of a plurality of connection terminals of the flexible circuit board are adhered to the conductive adhesive layer, and then the flexible circuit board and the bonding area are bonded together by a heat pressing device. 
     The connection terminals disposed at an adhering surface of the flexible circuit board adhered to the conductive adhesive layer are arranged in the bonding area. 
     S 40 : a waterproof rubber layer is formed in the first region to form a sealant layer in the non-display region, which consists of the waterproof rubber layer and the conductive adhesive layer. 
     The waterproof adhesive layer at least extends to a side surface of the flexible circuit board to ensure that moisture will not enter into the connection terminals of the flexible circuit board 
     In one embodiment, the conductive adhesive layer further includes a second insulating rubber material region formed at another, opposite side of the conductive-particles doped region. The second insulating rubber material region extends toward the first area and ends at one side edge of the bonding area. The first insulating rubber material region extends toward to the second area and ends at an edge of another, opposite side of the bonding area. 
     The rubber material of the conductive-particles doped region and the rubber material of the first insulating rubber material region and the second insulating rubber material region can be the same or different. 
     In the display panel and the bonding method of the display panel of the present disclosure, among a COF bonding process, an insulating rubber material layer is formed at one side or two sides of the conductive-particles doped region of the conductive adhesive layer to increase a width of the conductive adhesive layer. A front waterproof adhesive layer covers signal lines of a display area to form a sealed waterproofing area. Without increasing the equipment and cost for manufacturing the display panel, the present disclosure solve a corrosion risk of a back surface of OLED products, which cannot be applied with a waterproof adhesive layer after a COF bonding process. The present disclosure makes the back surface of OLED products not necessary to be coated with the waterproof adhesive layer, whereby to separate a glass substrate from the flexible OLED products can be conveniently proceeded with without adversely affecting the sequent processing; because the insulating rubber material layers formed at two sides of the conductive-particles doped region have a supporting function to make a same flowability in left and right sides of the conductive-particles doped region during a pressing process to promote a pressing accuracy. The problem of accurate pressing which may occur by a decreased size of the bonding area can be prevented by the present disclosure. The present disclosure can ensure that the conductive properties of the conductive-particles doped region are not affected, and also ensure that the signal lines of the non-display area are not in contact with the air to avoid the lines from corrosion, and to save the coating process, thereby to improve product quality and reliability and to improve a corrosion resistance of the product&#39;s use in an environment. 
     As is understood by persons skilled in the art, the foregoing preferred embodiments of the present disclosure are illustrative rather than limiting of the present disclosure. It is intended that they cover various modifications and that similar arrangements be included in the spirit and scope of the present disclosure, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structures.