Patent Publication Number: US-2022216084-A1

Title: Method for transferring electronic component

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 110100614 filed in Taiwan, R.O.C. on Jan. 7, 2021, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to transfer methods, and in particular to a method for transferring electronic components. 
     2. Description of the Related Art 
     Electronic devices nowadays have increasingly complicated functions, and the required numbers of their electronic components are on the rise, thanks to ever-changing technology and ever-increasing consumer needs. Ongoing trend toward miniaturization of electronic components is required to downsize electronic devices and enhance their performance. 
     For instance, light emitting diode (LED) display devices are one of the topics of research carried out on display units. However, to meet the requirement for high resolution, LED display devices are trending toward microscale LEDs arranged in an array and the resultant tremendous need of transfer. 
     Therefore, it is important to provide a method for transferring electronic components rapidly and precisely. 
     BRIEF SUMMARY OF THE INVENTION 
     An objective of the present disclosure is to provide a method for transferring electronic components, allowing the carrier substrate to face a surface of the transfer substrate in a manner that a portion of the electronic components are arranged corresponding to at least a portion of a plurality of cavities on the transfer substrate, and releasing and allowing the portion of electronic components that are arranged corresponding to the at least a portion of the plurality of cavities to fall into the cavities. The transfer substrate has a surface on which the plurality of cavities are formed. The cavities ensure that the electronic components fall into correct positions when released. Therefore, the method is effective in transferring electronic components rapidly and precisely. 
     Therefore, according to the present disclosure, a method for transferring electronic components is provided, such that the electronic components that are not arranged corresponding to the at least a portion of the plurality of cavities come into contact with the surface of the transfer substrate on which the plurality of cavities are not formed, and releasing and allowing the portion of electronic components that are arranged corresponding to the at least a portion of the plurality of cavities to fall into the cavities, thereby shortening the distance which separates the released electronic components from the transfer substrate. The transfer substrate has cavities for receiving electronic components of the carrier substrate. The cavities ensure that the electronic components fall into correct positions when released. Therefore, the method is effective in transferring electronic components rapidly and precisely and achieving satisfactory production yield. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  through  FIG. 1D  are schematic views of a process flow of a method for transferring electronic components according to an embodiment of the present disclosure. 
         FIG. 2A  through  FIG. 2F  are schematic views of a process flow of a method for transferring LED chips according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     To facilitate understanding of the object, characteristics and effects of this present disclosure, embodiments together with the attached drawings for the detailed description of the present disclosure are provided. 
       FIG. 1A  through  FIG. 1D  are schematic views of a process flow of a method for transferring electronic components according to an embodiment of the present disclosure. Referring to  FIG. 1A , a carrier substrate  110  and a transfer substrate  200  are provided. The carrier substrate  110  carries a plurality of electronic components  111 . The transfer substrate  200  has a surface  210  on which a plurality of cavities  211  are formed. The carrier substrate  110  is, for example, an adhesive film or a substrate with an adhesive film, and is adapted to adhere to and carry the plurality of electronic components  111 . The adhesive film is, for example, made of polyimide, but the present disclosure is not limited thereto. The transfer substrate  200  is a transparent substrate, for example, glass substrate, quartz substrate or sapphire substrate, but the present disclosure is not limited thereto. The plurality of electronic components  111  carried by the carrier substrate  110  have identical dimensions. The dimensions of the electronic components  111  are equal to or greater than 100 μm. The electronic components  111  are, for example, integrated circuit chips, but the present disclosure is not limited thereto. The dimensions of the electronic components  111  are not greater than 100 μm. The electronic components  111  are, for example, LED chips, for example, Mini LED chips or Micro LED chips, but the present disclosure is not limited thereto. The depth of the plurality of cavities is equal to or less than the height of the electronic components  111 . The plurality of cavities  211  are formed on the surface  210  of the transfer substrate  200  by a laser ablation or a chemical etching, but the present disclosure is not limited thereto. The laser for use in the laser ablation is, for example, visible light or invisible light. The chemical etching is, for example, dry etching or wet etching, but the present disclosure is not limited thereto. 
     Referring to  FIG. 1A , the plurality of electronic components  111  on the carrier substrate  110  face the surface  210  of the transfer substrate  200  in a manner that a portion of the electronic components  111  (for example, electronic components  111   a ) are arranged corresponding to at least a portion of the plurality of cavities  221  on the transfer substrate  200  but the other electronic components  111  (for example, electronic components  111   b ) not to align with the cavities  211  on the transfer substrate  200 , by image-based positioning, but the present disclosure is not limited thereto. 
     Referring to  FIG. 1B , the relative position of the carrier substrate  110  to the transfer substrate  200  are changed till the electronic components  111  that are not arranged corresponding to the at least a portion of the plurality of cavities  211  come into contact with the surface  210  of the transfer substrate  200  on which the plurality of cavities  211  are not formed, for example, by moving one of the carrier substrate  100  and the transfer substrate  200  toward the other, and the electronic components  111  (for example, electronic components  111   b ) not aligned with the cavities  211  come into contact with a cavity-free part (i.e., a part free of the cavities  211 ) of the surface  210  of the transfer substrate  200 . A force sensing or an optical distance sensing determines whether the electronic components  111  not aligned with the cavities  211  are in contact with a cavity-free part (i.e., a part free of the cavities  211 ) of the surface  210  of the transfer substrate  200 . 
     Referring to  FIG. 1C , the electronic components  111  (for example, electronic components  111   a ) that are arranged corresponding to the at least a portion of the plurality of cavities  211  are released and allowed to fall into the cavities. The release process is started by transferring energy to, for example, the electronic components  111  aligned with the cavities  211 , such that the adhesiveness of the adhesive layer of the carrier substrate  110  diminishes, thereby releasing the electronic components  111  from the carrier substrate  110 . The energy transfer is carried out by emitting a laser beam or ultrasonic waves toward the adhesive layers of the electronic components  111  aligned with the cavities  211 , as shown in  FIG. 1C , but the present disclosure is not limited thereto. 
     Referring to  FIG. 1D , the relative position of the carrier substrate  110  to the transfer substrate  200  is changed to draw the two substrates away from each other, such that one of the carrier substrate  100  and transfer substrate  200  moves away from the other, and the electronic components  111  aligned with the cavities  211  are not in contact with a cavity-free part (i.e., a part free of the cavities  211 ) of the surface  210  of the transfer substrate  200 . In this embodiment, the electronic components  111  disposed on the carrier substrate  100  but not aligned with the cavities  211  are further used in the next instance of transfer. 
     In this embodiment, the method for transferring the present disclosure enables the electronic components  111  disposed on the carrier substrate  110  but not aligned with the cavities  211  to come into contact with a cavity-free part (i.e., a part free of the cavities  211 ) of the surface  210  of the transfer substrate  200 , and then allows the electronic components  111  aligned with the cavities  211  to be released, such that the distance between the electronic components  111  on the carrier substrate  110  and the surface  210  of the transfer substrate  200  is capped by the height of the electronic components  111 , so as to reduce the distance which separates the electronic components  111  from the transfer substrate  200  and lower the chance that the electronic components  111  will, in the course of its fall, drift or separate from the transfer substrate  200 . The transfer substrate  200  has the cavities  211  for receiving the electronic components  111  of the carrier substrate  110 . When released, the electronic components  111  are guided by the cavities  211  to their correct positions. Therefore, the method for transferring electronic components of the present disclosure enhances production yield. 
     The method for transferring LED chips is described above step by step and below generally. 
     Referring to  FIG. 2A , the method for transferring electronic components illustrated with FIG. lA through  FIG. 1D  provides a carrier substrate  110  and a transfer substrate  200 . The plurality of electronic components  111  on the carrier substrate  110  face the surface  210  of the transfer substrate  200 . The plurality of cavities  211  are disposed on the surface  210 . A portion of the electronic components  111  are aligned with the plurality of cavities  211  on the transfer substrate  200 . Then, the relative position of the carrier substrate  110  to the transfer substrate  200  is changed, and the electronic components  111  not aligned with the cavities  211  come into contact with a cavity-free part (i.e., a part free of the cavities  211 ) of the surface  210  of the transfer substrate  200 . Then, the electronic components  111  disposed on the carrier substrate  110  and aligned with the cavities  211  are released to the cavities  211 . The electronic components  111  are LED chips which emit red (R) light. 
     Referring to  FIG. 2B , the method for transferring electronic components illustrated with  FIG. 1A  through  FIG. 1D  provides a carrier substrate  120 . The plurality of electronic components  121  on the carrier substrate  120  face the surface  210  of the transfer substrate  200 . The plurality of cavities  211  are disposed on the surface  210 . A portion of the electronic components  121  (for example, electronic components  121   a ) are aligned with the cavities  211  disposed on the transfer substrate  200  but not receiving the electronic components  111 . Then, the relative position of the carrier substrate  120  to the transfer substrate  200  is changed, and the electronic components  121  (for example, electronic components  121   b ) not aligned with the cavities  211  come into contact with a cavity-free part (i.e., a part free of the cavities  211 ) of the surface  210  of the transfer substrate  200 . Then, the electronic components  111  disposed on the carrier substrate  120  and aligned with the cavities  211  are released to the cavities  211 . The electronic components  121  are LED chips which emit green (G) light. 
     Referring to  FIG. 2C , the method for transferring electronic components illustrated with  FIG. 1A  through  FIG. 1D  provides a carrier substrate  130 . The plurality of electronic components  131  on the carrier substrate  130  face the surface  210  of the transfer substrate  200 . The plurality of cavities  211  are disposed on the surface  210 . A portion of the electronic components  131  (for example, electronic components  131   a ) are aligned with the cavities  211  disposed on the transfer substrate  200  but not receiving the electronic components  111  or electronic components  121 . Then, the relative position of the carrier substrate  130  to the transfer substrate  200  is changed, and the electronic components  131  (for example, electronic components  131   b ) not aligned with the cavities  211  come into contact with a cavity-free part (i.e., a part free of the cavities  211 ) of the surface  210  of the transfer substrate  200 . Then, the electronic components  131  disposed on the carrier substrate  130  and aligned with the cavities  211  are released to the cavities  211 . The electronic components  131  are LED chips which emit blue (B) light. Therefore, the cavities  211  of the transfer substrate  200  each receive one of the electronic component  111 , electronic component  121  and electronic component  131 . The electronic components  111 , electronic components  121  and electronic components  131  are arranged in a pixel array in the plurality of cavities  211  of the transfer substrate  200 . 
     Referring to  FIG. 2D , a carrier substrate  300  is provided. The carrier substrate  300  has a surface  310  with an adhesive film  311  thereon. 
     Referring to  FIG. 2E , the surface  310  of the carrier substrate  300  faces the surface  210  of the transfer substrate  200 . The plurality of cavities  211  are disposed on the surface  210 . The relative position of the carrier substrate  300  to the transfer substrate  200  is changed. The adhesive film  311  of the carrier substrate  300  comes into contact with and thus adheres to the electronic components  111 ,  121 ,  131  in the plurality of cavities  211  of the transfer substrate  200 . 
     Referring to  FIG. 2F , the relative position of the carrier substrate  300  to the transfer substrate  200  is changed to draw the two substrates away from each other, such that the electronic components  111 ,  121  or  131  received in the cavities  211  are adhered to the surface  310  of the carrier substrate  300  and leave the cavities  211  and thus are transferred to the carrier substrate  300 . 
     In this embodiment, the pixel array formed on the transfer substrate  200  depends on the pixel array of the circuit substrate of a display device. Therefore, the electronic components  111 ,  121 ,  131  transferred to the carrier substrate  300  and pixel array thus formed can be transferred to the circuit substrate of the display device in one single instance of a transfer process. Therefore, the method for transferring electronic components of the present disclosure is effective in transferring a large number of pixels on the circuit substrate rapidly and precisely, reducing the transfer cost incurred in a display device manufacturing process, and achieving satisfactory production yield. 
     In conclusion, the method for transferring electronic components of the present disclosure enables electronic components disposed on a carrier substrate but not aligned with cavities therein to come into contact with a cavity-free part of a surface of a transfer substrate and then allows the electronic components aligned with the cavities to be released, so as to shorten the distance which separates the electronic components of the carrier substrate from the surface of the transfer substrate and lower the chance that the electronic components will, in the course of its fall, drift or separate from the transfer substrate. Furthermore, the transfer substrate has cavities for receiving the electronic components of the carrier substrate, such that the released electronic components are guided by the cavities to their correct positions. Therefore, the method for transferring electronic components of the present invention has satisfactory production yield. 
     While the present disclosure has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the present disclosure set forth in the claims.