Patent Publication Number: US-2023156994-A1

Title: Apparatus for repairing element

Description:
TECHNICAL FIELD 
     The present invention relates to an apparatus for repairing elements, which can prevent damage to a new element during transfer of the new element and can ensure a safe repair process. 
     BACKGROUND ART 
     In general, an element module including multiple elements mounted on a substrate undergoes testing to inspect defective elements, and a process of removing an element determined to be defective and replacing the element with a new element is called a repair process. 
     Repair devices used in the repair process include a device for separating a defective element from a substrate by melting a solder on the defective element, a device for mounting a new element on the substrate, and the like. 
     However, a conventional element repair process has a problem in that excessive pressure can be applied to a new element during transfer of the new element, causing damage to the new element. In addition, in order to prevent this problem, various types of sensors are required to measure the pressure applied to elements or to monitor the condition of elements, which results in a complicated apparatus configuration. 
     Further, there is a problem that, during removal of a defective element or transfer of a new element, other normal elements separate from the defective element are likely to be damaged. 
     Recently, with development of nanotechnology, the size of elements has become smaller and smaller. However, a conventional apparatus for repairing elements is difficult to use for microelements due to the physical size of a vacuum suction tool. Therefore, there is a need for element repair technology that can effectively remove a defective microelement from a substrate having multiple microelements arranged thereon and can reliably replace the defective microelement with a new microelement. 
     DISCLOSURE 
     Technical Problem 
     Embodiments of the present invention are conceived to solve such problems in the art and it is an object of the present invention to provide an apparatus for repairing elements, which can prevent damage to a new element during transfer of the new element and can ensure a safe repair process. 
     It will be understood that objects of the present invention are not limited to the above. 
     The above and other objects of the present invention will become apparent to those skilled in the art from the detailed description of the following embodiments in conjunction with the accompanying drawings 
     Technical Solution 
     In accordance with one aspect of the present invention, an apparatus for repairing elements includes: a bonding material transfer stamp transferring a new bonding material to a repair area on a substrate, the repair area having a defective element or a residual bonding material removed therefrom; and an element transfer stamp transferring a new element to the new bonding material, wherein the element transfer stamp includes a load control portion for elements, the load control portion being bent and deformed upon receiving pressing force such that a zero-stiffness load smaller than a critical damage load of the new element is applied to the new element. 
     In one embodiment, the apparatus for repairing elements may further include: a removal stamp removing a defective element on a substrate and a residual bonding material remaining after removal of the defective element. 
     In one embodiment, the removal stamp may include: multiple pads contacting the defective element, one of the multiple pads being selected to be adhesively attached to the defective element. 
     In one embodiment, the removal stamp may further include: a tape having a lower surface to which the multiple pads are attached in a row, the tape being fed by a pair of rollers spaced apart from each other and connected to the tape; and a pressing head disposed on an upper surface of the tape to be vertically movable and pressing the tape downward to press one of the multiple pads against the defective element. 
     In one embodiment, the removal stamp may include: an attachment film having a lower surface to which the multiple pads are attached in the form of an array; and a pressing rod disposed above the attachment film to be horizontally/vertically movable and pressing the attachment film downward to press one of the multiple pads against the defective element. 
     In one embodiment, the pad may include: a receiving groove formed on a lower surface of the pad to receive the defective element therein; a heater disposed around the receiving groove; and an adhesive layer disposed in the receiving groove and heated by the heater to allow the defective element received in the receiving groove to be adhesively attached to the adhesive layer. 
     In one embodiment, the heater may be an induction heater inductively heating a bonding material electrically connecting the defective element to the substrate. 
     In one embodiment, the removal stamp may further include: a load control portion for removal, the load control portion being bent and deformed upon receiving pressing force such that a zero-stiffness load smaller than a critical damage load of the defective element is applied to the defective element. 
     In one embodiment, the element transfer stamp may further include: a fluid inlet through which a fluid supplied from an exterior passes; an elastic layer inflated downward by the fluid introduced through the fluid inlet, the elastic layer having adhesive strength; and a flow rate control portion controlling a flow rate of the fluid through the fluid inlet to regulate adhesion between the elastic layer and the new element. 
     In one embodiment, the apparatus for repairing elements may further include: a reflow stamp bonding the new element to the new bonding material by pressing and heating the new element, wherein the reflow stamp may include a pressure heater heating the new element and the new bonding material while pressing the new element and a buffer layer disposed around the pressure heater, the buffer layer being brought into close contact with elements around the new element when the pressure heater presses the new element. 
     In one embodiment, the reflow stamp may further include: a load control portion for reflow, the load control portion being bent and deformed upon receiving pressing force such that a zero-stiffness load smaller than a critical damage load of the new element is applied to the new element. 
     In one embodiment, the bonding material transfer stamp may further include: a tape having a lower surface to which multiple new bonding materials are attached in a row, the tape being fed by a pair of rollers spaced apart from each other and connected to the tape; and a pressing head disposed on an upper surface of the tape to be vertically movable and pressing the tape downward to press one of the multiple new bonding materials against the repair area. 
     In one embodiment, the bonding material transfer stamp may further include: an attachment film having a lower surface to which multiple new bonding materials are attached in the form of an array; and a pressing rod disposed above the attachment film to be horizontally/vertically movable and pressing the attachment film downward to press one of the multiple new bonding materials against the repair area. 
     In one embodiment, the element transfer stamp may further include: a tape having a lower surface to which multiple new elements are attached in a row, the tape being fed by a pair of rollers spaced apart from each other and connected to the tape; and a pressing head disposed on an upper surface of the tape to be vertically movable and pressing the tape downward to press one of the multiple new elements against the new bonding material. 
     In one embodiment, the element transfer stamp may further include: an attachment film having a lower surface to which multiple new elements are attached in the form of an array; and a pressing rod disposed above the attachment film to be horizontally/vertically movable and pressing the attachment film downward to press one of the multiple new elements against the new bonding material. 
     Advantageous Effects 
     According to embodiments of the present invention, an element transfer stamp transferring a new element to a new bonding material includes a load control portion for elements, the load control portion being bent and deformed upon receiving pressing force such that a zero-stiffness load smaller than a critical damage load of the new element is applied to the new element, thereby preventing damage to a new element during transfer of the new element. 
     It will be understood that advantageous effects of the present invention are not limited to the above and include any advantageous effects conceivable from the features disclosed in the detailed description of the present invention or the appended claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic view of an apparatus for repairing elements according to a first embodiment of the present invention, focusing on a bonding material transfer stamp thereof 
         FIG.  2    is a schematic view of the apparatus for repairing elements according to the first embodiment of the present invention, focusing on an element transfer stamp thereof. 
         FIG.  3    is a schematic view illustrating an exemplary operation of the element transfer stamp of  FIG.  2   . 
         FIG.  4    is a view illustrating deformation of a load control portion for elements of  FIG.  3    and a graph of the resulting displacement-load relation. 
         FIG.  5    is a schematic view illustrating an example of the element transfer stamp of  FIG.  2   . 
         FIG.  6    is a schematic view of another example of the element transfer stamp of  FIG.  2   . 
         FIG.  7    is a schematic view of the apparatus for repairing elements according to the first embodiment of the present invention, focusing on a reflow stamp thereof 
         FIG.  8    is a schematic view of an apparatus for repairing elements according to a second embodiment of the present invention, focusing on a removal stamp thereof. 
         FIG.  9    is a schematic view of an example of the removal stamp of  FIG.  8   . 
         FIG.  10    is a schematic view illustrating an exemplary operation of the removal stamp of  FIG.  8   . 
         FIG.  11    is an exemplary view of the pad of  FIG.  9   . 
         FIG.  12    is a schematic view illustrating an exemplary operation of the pad of  FIG.  11   . 
         FIG.  13    is a schematic view of another example of the removal stamp of  FIG.  8   . 
         FIG.  14    is a schematic view illustrating an exemplary operation of the removal stamp of  FIG.  13   . 
     
    
    
     MODE FOR INVENTION 
     Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. It should be understood that the present invention may be embodied in different ways and is not limited to the following embodiments. In the drawings, portions irrelevant to the description will be omitted for clarity. Like components will be denoted by like reference numerals throughout the specification. 
     Throughout the specification, when an element or layer is referred to as being “on”, “connected to”, or “coupled to” another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. In addition, unless stated otherwise, the term “includes” should be interpreted as not excluding the presence of other components than those listed herein. 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     Moreover, the terms “comprises”, “comprising,” “includes.” and/or “including” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. 
       FIG.  1    is a schematic view of an apparatus for repairing elements according to a first embodiment of the present invention, focusing on a bonding material transfer stamp thereof 
     Referring to  FIG.  1   , the apparatus for repairing elements may include a bonding material transfer stamp  100  and an element transfer stamp  200 . 
     The bonding material transfer stamp  100  may transfer a new bonding material  21  to a repair area RA on a substrate  10  disposed on a stage  900 , wherein the repair area RA is an area from which a defective element or a residual bonding material has been removed. 
     The stage  900  may be moved in virtual X- and Y-axis directions on a horizontal plane. In addition, the apparatus for repairing elements may further include a vacuum chuck disposed on an upper surface of the stage  900  to prevent slipping between the stage  900  and the substrate  10  during movement of the stage  900 . Here, the substrate  10  may be disposed on the vacuum chuck to be movable in conjunction with movement of the stage  900 . 
     The substrate  10  may be a substrate that has undergone an element transfer process. In general, transfer of an element to the substrate  10  may be considered as defective when the element has failed to be transferred to the substrate, when the element transferred to the substrate is not accurately aligned with a bonding material, when damage to the element has occurred, or when electrical connection between the element and the bonding material is poor. The apparatus for repairing elements according to this embodiment may be used when the element has failed to be transferred to the substrate. 
     The bonding material transfer stamp  100  may transfer a new bonding material  21  to the repair area RA where there is no bonding material placed. Here, the new bonding material  21  may be of the same material as a bonding material  11  already placed on the substrate  10 , and may include a flux, a solder paste, an anisotropic conductive film (ACF), an anisotropic conductive paste (ACP), a non-conductive film (NCF), and the like. 
     The bonding material transfer stamp  100  may include a transfer tip  110  to transfer the new bonding material  21  to the substrate  10 . As shown in  FIG.  1 ( b ) , the bonding material transfer stamp  100  may be configured to be movable in a horizontal direction so as to transfer the new bonding material  21  to the substrate  10 . Alternatively, the bonding material transfer stamp  100  may include a large-area transfer tip  110  or a plurality of transfer tips  110  corresponding to the shape in which the new bonding material  21  will be transferred to the substrate  10  so as to transfer the new bonding material  21  to the substrate  10  without moving in the horizontal direction. 
     In addition, the bonding material transfer stamp  100  may further include a cleaning tip (not shown) to clean an electrode (not shown) on the substrate  10  to which the new bonding material  21  will be transferred. 
     The element transfer stamp  200  may be disposed to one side of the bonding material transfer stamp  100  and the substrate  10  having the new bonding material  21  transferred thereto may be moved under the element transfer stamp  200  by the stage  900 . 
       FIG.  2    is a schematic view of the apparatus for repairing elements according to the first embodiment of the present invention, focusing on the element transfer stamp and  FIG.  3    is a schematic view illustrating an exemplary operation of the element transfer stamp of  FIG.  2   . 
     Referring to  FIG.  2    and  FIG.  3   , the element transfer stamp  200  may transfer a new element  22  to the new bonding material  21 . 
     The element transfer stamp  200  may include a load control portion  230  for elements. The load control portion  230  for elements may be bent and deformed upon receiving pressing force to allow a zero-stiffness load smaller than a critical damage load of the new element  22  to be applied to the new element  22 . First, the load control portion  230  for elements will be described in detail. 
       FIG.  4    is a view illustrating deformation of the load control portion for elements of  FIG.  3    and a graph of the resulting displacement-load relation. In  FIG.  4 ( d ) , a first curve (C 1 ) is a load-displacement curve of the element transfer stamp with the load control portion for elements and a second curve (C 2 ) is a load-displacement curve of a stamp without the load control portion for elements. 
     Referring to  FIG.  4   , the load control portion  230  for elements may include a base  231 , a pillar  233 , and a plate  237 . 
     The base  231  may be formed flat and the pillar  233  may be connected at one end  234  thereof to one surface of the base  231 . The plate  237  may adjoin the other end  235  of the pillar  233 . Upon application of external force in an axial direction of the pillar  233 , the pillar  233  may be bent and deformed. Here, bending deformation of the pillar  233  may include buckling. 
     In the element transfer stamp  200 , the load control portion  230  for elements may be positioned such that external force applied thereto is transferred to the pillar  233  through the plate  237 . However, it will be understood that the present invention is not limited thereto and the load control portion  230  for elements may be positioned such that external force applied thereto is transferred to the pillar  233  through the base  231 . 
     Each of the base  231 , the pillar  233 , and the plate  237  may be formed of at least one selected from among silicone rubber, urethane rubber, fluororubber, ethylene-propylene-diene rubber (EPDM), nitrile-butadiene rubber (NBR), polymethyl methacrylate (PMMA), and a photoresist. 
     In one embodiment, the load control portion  230  for elements may be directly manufactured through a photolithography process using a UV light source, a 3D printing process, or a LIGA process using X-rays. Here, as a material for the load control portion  230  for elements, at least one selected from among silicone rubber, PMMA, and an epoxy-based negative photoresist may be used. 
     In another embodiment, the load control portion  230  for elements may be manufactured by a method including: fabricating a mold corresponding in shape to the load control portion  230  for elements through a 3D printing process or a LIGA process; and forming the load control portion for elements by injecting a molding liquid into the mold, followed by curing. 
     The molding liquid may include at least one selected from among silicone rubber, urethane rubber, fluororubber, EPDM, and NBR. The molding liquid may be cured by room-temperature vulcanization or high-temperature vulcanization. 
     Referring to  FIG.  4   , when the pillar  233  is bent and deformed by a first displacement d 1  and then further bent and deformed to a second displacement d 2  greater than the first displacement d 2  by receiving external force through the plate  237 , the load control portion  230  for elements according to the present invention may generate a zero-stiffness load F 1  within the displacement range from the first displacement d 1  to the second displacement d 2 . That is, the load control portion  230  for elements may have a displacement-load relation having a zero-stiffness zone, in which load generated by the load control portion  230  for elements remains at a constant level F 1 , over the displacement range from the first displacement d 1  to the second displacement d 2 . 
     In other words, when the load control portion  230  for elements undergoes compressive deformation by external force, load generated by the load control portion  230  for elements does not increase within a specific displacement range. This means that, when an appropriate amount of pressing force is provided such that the load control portion  230  for elements is deformed within the specific displacement range, uniform contact pressure can be applied between the new element  22  and the substrate  10 . 
     Accordingly, even when the new element  22  is subjected to a strain d 3 , which can cause the new element  22  to reach a critical damage load F 2  thereof, upon receiving pressing force due to machining errors of each component of the element transfer stamp  200 , assembly errors between various components including thickness errors of the new element  22 , or load control errors that may occur during control of load applied to the new element  22 , it is possible to prevent damage to the new element if the load control portion  230  for elements provides a zero-stiffness load F 1  smaller than the critical damage load F 2  of the new element  22 . 
     Referring back to  FIG.  2    and  FIG.  3   , the element transfer stamp  200  may include a first pressing force providing portion  210  and a first pressing portion  220 . 
     The first pressing force providing portion  210  may be disposed on an upper surface of the load control portion  230  for elements and may provide downward pressing force to the load control portion  230  for elements. 
     The first pressing portion  220  may be disposed on a lower surface of the load control portion  230  for elements and may press the new element  22  against the new bonding material  21  on the substrate  10 . 
     Although the load control portion  230  for elements is shown as being entirely disposed between the first pressing force providing portion  210  and the first pressing portion  220 , it should be understood that the present invention is not limited thereto and the load control portion  230  for elements may be partially disposed between the pressing force providing portion  210  and the first pressing portion  220 . When the load control portion  230  for elements is partially disposed between the first pressing force providing portion  210  and the first pressing portion  220 , it is desirable that the load control portion  230  be positioned to be symmetric with respect to a central axis of the element transfer stamp  200 . 
     In addition, although the load control portion  230  for elements is shown as being positioned such that the base  231  closely contacts an upper surface of the first pressing portion  220  and the plate  237  closely contacts a lower surface of the first pressing force providing portion  210 , it should be understood that the present invention is not limited thereto and the load control portion  230  for elements may be positioned such that the base  231  closely contacts the lower surface of the first pressing force providing portion  210  and the plate  237  closely contacts the upper surface of the first pressing portion  220 . 
       FIG.  5    is a schematic view illustrating an example of the element transfer stamp of  FIG.  2   . 
     Referring to  FIG.  5   , the element transfer stamp  200  may further include a fluid inlet  221 , an elastic layer  250 , and a flow rate control portion  260 . 
     The fluid inlet  221  may be formed in the element transfer stamp  200  to allow a fluid supplied from an exterior to pass through the element transfer stamp  200 . The fluid inlet  221  may be provided in the form of a through-hole. Specifically, the fluid inlet  221  may be formed through the first pressing portion  220  such that the fluid can be discharged below the first pressing portion  220 . The fluid may include a gas or a liquid. 
     The elastic layer  250  may be inflated downward by the fluid introduced through the fluid inlet  221 . The elastic layer  250  may be disposed on the lower surface of the first pressing portion  220  to cover the fluid inlet  221 . Accordingly, when the fluid introduced through the fluid inlet  221  is discharged from the fluid inlet  221 , the elastic layer  250  may be inflated by the fluid. 
     In addition, the elastic layer  250  may have adhesive strength such that the new element  22  is adhesively attached to a lower surface of the elastic layer  250 . An area over which adhesion between the elastic layer  250  and the new element  22  occurs may be controlled through regulation of the degree of inflation of the elastic layer  250 . When adhesion between the elastic layer  250  and the new element  22  occurs over a larger area, larger pressing force is applied to the new element  22  and, when adhesion between the elastic layer  250  and the new element  22  occurs over a smaller area, smaller pressing force is applied to the new element  22 . 
     In another embodiment, once the elastic layer  250  is inflated to a certain degree by the fluid supplied thereto, the shape of the elastic layer  250  does not change regardless of the pressure of the fluid. With the elastic layer  250  inflated to the certain degree, when the pressure of the fluid is high, large pressing force is applied to the new element  22  by the elastic layer  250  and, when the pressure of the fluid is low, small pressing force is applied to the new element  22  by the elastic layer  250 . 
     Since the elastic layer  250  elastically presses the new element  22 , use of the elastic layer  250  is effective in preventing damage to the upper surface of the new element  22 , such as scratches, as compared with when the pressing portion formed of a hard material directly presses the new element  22 . 
     The flow rate control portion  260  may control a flow rate of the fluid through the fluid inlet  221 . In this way, the flow rate control portion  260  can control adhesion between the elastic layer  250  and the new element  22 . 
       FIG.  6    is a schematic view of another example of the element transfer stamp of  FIG.  2   . 
     Referring to  FIG.  6   , the element transfer stamp  200  may further include a protruding head  270 . The protruding head  270  may protrude from the lower surface of the first pressing portion  220  and the fluid inlet  221  may extend through the protruding head  270 . In addition, the elastic layer  250  may be disposed on a lower surface of the protruding head  270 . 
     Since the protruding head  270  increases a distance between the elastic layer  250  and the first pressing portion  220 , it is possible to prevent the first pressing portion  220  of the element transfer stamp  200  from pressing and damaging normal elements  12  already mounted around the repair area RA when the element transfer stamp  200  approaches the substrate  10  to transfer the new element  22  to the substrate  10 . 
     The apparatus for repairing elements may further include a reflow stamp  300 . The reflow stamp  300  may be disposed to one side of the element transfer stamp  200 . The substrate  10  having the new element  22  transferred thereto may be moved under the reflow stamp  300  by the stage  900 . 
       FIG.  7    is a schematic view of the apparatus for repairing elements according to the first embodiment of the present invention, focusing on the reflow stamp. 
     Referring to  FIG.  7   , the reflow stamp  300  may press and heat the new element  22  to bond the new element  22  to the new bonding material  21 . 
     The reflow stamp  300  may include a second pressing force providing portion  310  and a second pressing portion  320 . 
     The second pressing force providing portion  310  may provide downward pressing force. 
     The second pressing portion  320  may press the new element  22  on the substrate  10  by receiving pressing force from the second pressing force providing portion  310 . 
     In addition, the reflow stamp  300  may include a pressure heater  340  and a buffer layer  350 . 
     The pressure heater  340  may heat the new element  22  and the new bonding material  21  while pressing the new element  22 . The pressure heater  340  may be disposed on a lower surface of the second pressing portion  320 . 
     The buffer layer  350  may be disposed around the pressure heater  340 . The buffer layer  350  may be disposed on the lower surface of the second pressing portion  320 . The buffer layer  350  may be brought into close contact with elements  12  around the new element  22  when the pressure heater  340  presses the new element  22 . The buffer layer  350  closely contacting the elements  12  can protect the elements  12  by preventing a load sufficient to cause damage to the elements  12  from being transferred to the elements  12 . 
     In addition, the reflow stamp  300  may include a load control portion  330  for reflow. The load control portion  330  for reflow may be disposed between the second pressing force providing portion  310  and the second pressing portion  320 . Upon application of pressing force, the load control portion  330  for reflow may be bent and deformed such that a zero-stiffness load smaller than a critical damage load of the new element  22  can be applied to the new element  22 . The load control portion  330  for reflow may have the same configuration as the load control portion  230  for elements (see  FIG.  2   ). 
     Here, the zero-stiffness load generated by the load control portion  330  for reflow may be smaller than the zero-stiffness load generated by the load control portion  230  for elements. 
     Since the new bonding material  21  is heated and becomes viscous during the reflow process, the new element  22  can be sufficiently pressed against the new bonding material  21  with pressing force smaller than pressing force applied to the new element  22  during the process of transferring the new element  22  to the new bonding material  21  using the element transfer stamp  200 . 
       FIG.  8    is a schematic view of an apparatus for repairing elements according to a second embodiment of the present invention, focusing on a removal stamp thereof. Among the aforementioned types of defective transfer of an element to a substrate, the apparatus for repairing elements according to this embodiment may be used when the element transferred to the substrate is not accurately aligned with a bonding material, when damage to the element has occurred, or when electrical connection between the element and the bonding material is poor. 
     Since the apparatus for repairing elements according to this embodiment is substantially the same as the apparatus for repairing elements according to the first embodiment except that the apparatus for repairing elements according to this embodiment further includes a removal stamp  400 , redundant description thereof will be omitted. 
     Referring to  FIG.  8   , the removal stamp  400  may remove a defective element  15  on a substrate  10  and a residual bonding material  16  remaining after removal of the defective element  15 . That is, the removal stamp  400  may remove both the defective element  15  on the substrate  10  and the residual bonding material  16  remaining in a repair area RA with the defective element  15  removed therefrom. 
     The removal stamp  400  may include a pad  454 . The pad  454  may include multiple pads and a selected one  454  of the multiple pads may be adhesively attached to the defective element  15 . 
     The removal stamp  400  may include a third pressing force providing portion  410  and a third pressing portion  420 . 
     The third pressing force providing portion  410  may provide downward pressing force. 
     The third pressing portion  420  may receive pressing force from the third pressing force providing portion  410 , and the pad  454  may be pressed against the defective element  15  by pressing force of the third pressing portion  420 . 
       FIG.  9    is a schematic view of an example of the removal stamp of  FIG.  8   , and  FIG.  10    is a schematic view illustrating an exemplary operation of the removal stamp of  FIG.  8   . 
     Referring further to  FIG.  9    and  FIG.  10   , the removal stamp  400  may include a tape  453  and a pressing head  455 . The tape  453  may be connected to a pair of rollers  451 ,  452  spaced apart from each other. The tape  453  may be wound around the second roller  452  while being unwound from the first roller  451 . 
     The multiple pads  454  may be attached in a row to the tape  453 . Specifically, the multiple pads  454  may be attached to a lower surface of the tape  453  unwound from the first roller  451  and may protrude downward. 
     The pressing head  455  may be disposed on an upper surface of the tape  453  to be vertically movable. To this end, the pressing head  455  may be provided on an upper surface thereof with a lifting block  456 . The pressing head  455  may be vertically moved in conjunction with vertical movement of the lifting block  456 . 
     The removal stamp  400  may include a load control portion  430  for removal. The load control portion  430  for removal may be disposed between the third pressing force providing portion  410  and the third pressing portion  420 . 
     When the removal stamp is configured such that the lifting block  456  is vertically moved with the third pressing portion  420  remaining in a stationary state, a load control portion  430   a  for removal may be disposed between the third pressing force providing portion  410  and an upper surface of the lifting block  456 . The load control portion  430   a  for removal may be bent and deformed upon receiving pressing force from the third pressing force providing portion  410  such that a zero-stiffness load smaller than a critical damage load of the defective element  15  is transferred to the lifting block  456 . As a result, the pressing head  455  can apply the zero-stiffness load smaller than the critical damage load of the defective element  15  to the defective element  15 . 
     Alternatively, when the removal stamp is configured such that the third pressing portion  420  is vertically moved in conjunction with vertical movement of the lifting block  456 , a load control portion  430   b  for removal may be disposed between the third pressing force providing portion  410  and both the upper surface of the lifting block  456  and the upper surface of the third pressing portion  420 . The load control portion  430   b  for removal may be bent and deformed upon receiving pressing force from the third pressing force providing portion  410  such that a zero-stiffness load smaller than a critical damage load of the defective element  15  is transferred to both the lifting block  456  and the third pressing portion  420 . As a result, the pressing head  455  can press the tape  453  downward with the zero-stiffness load smaller than the critical damage load of the defective element  15  such that one of the multiple pads attached in a row to the tape  453  can be pressed against the defective element  15 . 
     Each pad  454  is usable for one defective element  15 . Since a pad used to remove one defective element  15  is not reusable, a new pad  454  needs to be positioned at a lower center of the pressing head  455  in order to remove another defective element  15 . In this embodiment, after using one pad  454   a  to remove one defective element  15 , the first roller  451  and the second roller  452  may be rotated to feed the tape such that a new pad  454   b  is positioned at the lower center of the pressing head  455 , as shown in  FIG.  10 ( a ) . After removing another defective element using the pad  454   b,  the tape  453  may be fed again to use a new pad  454   c.  The load control portion  430  for removal may have the same configuration as the load control portion  230  for elements (see  FIG.  2   ). 
     The bonding material transfer stamp  100  (see  FIG.  1   ) may also adopt the configuration described in  FIG.  9    to place a new bonding material on the repair area. That is, the bonding material transfer stamp  100  may further include: the tape described above having new bonding materials, instead of the pads, attached in a row to a lower surface thereof; and a pressing head pressing one of the new bonding materials against the repair area to transfer the new bonding material to the repair area. 
     In addition, the element transfer stamp  200  (see  FIG.  2   ) may adopt the configuration described in  FIG.  9    to place a new element on a new bonding material. That is, the element transfer stamp  200  may further include the tape described above having new elements, instead of the pads, attached in a row to a lower surface thereof; and a pressing head pressing one of the new elements against a new bonding material to transfer the new element to the new bonding material. Here, it is obvious that the element transfer stamp  200  may include the load control portion for elements instead of the load control portion for removal  430   a  or  430   b  described above. 
       FIG.  11    is an exemplary view of the pad of  FIG.  9   , and  FIG.  12    is a schematic view illustrating an exemplary operation of the pad of  FIG.  11   . 
     Referring to  FIG.  11    and  FIG.  12   , the pad  454  may include a receiving groove  461 , a heater  463 , and an adhesive layer  465 . 
     The receiving groove  461  may be formed on a lower surface of the pad  454  to receive a defective element  15  therein. 
     The heater  463  may be disposed around the receiving groove  461 . The heater  463  may be disposed on the lower surface of the pad  454 . 
     The adhesive layer  465  may be disposed in the receiving groove  461 . The adhesive layer  465  may be heated by the heater  463  to allow the defective element  15  in the receiving groove  461  to be adhesively attached thereto. The adhesive layer  465  may be a thermosetting polymer that hardens when heated to a temperature higher than or equal to a curing temperature thereof, or may be a thermoplastic polymer that melts when heated and hardens again when cooled. 
     When the pad  454  is moved downward and the defective element  15  is inserted into the receiving groove  461 , the defective element  15  may contact the adhesive layer  465  (see  FIG.  12 ( a )  and see  FIG.  12 ( b ) ). 
     Then, when the heater  463  generates heat, the adhesive layer  465  may be heated and melted and the defective element  15  may be inserted into the adhesive layer  465  by downward load of the pad  454  (see  FIG.  12 ( c ) ). When a thermosetting adhesive layer is used, the defective element  15  can be firmly secured to the adhesive layer  465  as the adhesive layer  465  is cured by heating. When a thermoplastic adhesive layer is used, the defective element  15  can be firmly secured to the adhesive layer  465  while being inserted into the adhesive layer  465 . When the heater  463  continues to heat the adhesive layer, a bonding material bonded to the defective element  15  is melted by heat transferred thereto. Here, bonding strength between the cured adhesive layer  465  and the defective element  15  is greater than bonding strength between the defective element  15  and the molten bonding material  16 . Accordingly, when the pad  454  is moved upward, the defective element  15  can be removed from the substrate  10  (see  FIG.  12 ( d ) ). 
     The heater  463  may be an induction heater. When the heater  463  is an induction heater, the bonding material  16  may be inductively heated by the heater  463 . Accordingly, the adhesive layer  645  may also be heated and melted together with the bonding material  16   a  by heat transferred from the heater  463 , whereby the defective element  15  and the bonding material  16  can be more easily removed from the substrate  10  upon moving the pad  454  upward. 
       FIG.  13    is a schematic view of another example of the removal stamp of  FIG.  8   , and  FIG.  14    is a schematic view illustrating an exemplary operation of the removal stamp of  FIG.  13   . 
     Referring to  FIG.  13    and  FIG.  14   , the removal stamp  400  may include an attachment film  471  and a pressing rod  475 . 
     The attachment film  471  may be positioned horizontally and may include multiple pads  474  attached in the form of an array to a lower surface thereof. The pads  474  attached to the lower surface of the attachment film  471  may protrude downward. 
     The pressing rod  475  may be disposed above the attachment film  471  to be horizontally movable. Specifically, the removal stamp  400  may further include a horizontal guide  472  extending in the X- and Y-axis directions in a horizontal plane and a slider  476  slidingly coupled to the horizontal guide  472  and connected to the pressing rod  475 . Accordingly, the pressing rod  475  may be movable horizontally. 
     In addition, the pressing rod  475  may also be vertically movable above the attachment film  471 . 
     In this embodiment, a load control portion  430   c  for removal may be disposed between the third pressing force providing portion  410  and an upper surface of the pressing rod  475 . The load control portion  430   c  for removal may be bent and deformed upon receiving pressing force from the third pressing force providing portion  410  such that a zero-stiffness load smaller than a critical damage load of a defective element  15  is transferred to the pressing rod  475 . As a result, the pressing rod  475  can apply the zero-stiffness load smaller than the critical damage load of the defective element  15  to the defective element  15 . The pressing rod  475  may press the attachment film  471  downward such that one of the multiple pads  474  attached in the form of an array to the attachment film  471  is pressed against the defective element  15 . 
     After one pad  474   a  is used to remove one defective element, the pressing rod  475  may be horizontally moved to a position over a new pad  474   b.  Then, the pressing rod  475  may be moved downward to remove another defective element using the pad  474   b,  and then may be moved horizontally again to use a new pad  474   c.    
     The bonding material transfer stamp  100  (see  FIG.  1   ) may also adopt the configuration described in  FIG.  13    to place a new bonding material on the repair area. That is, the bonding material transfer stamp  100  may further include: the attachment film described above having multiple new bonding materials, instead of the pads, attached in the form of an array to the lower surface thereof; and a pressing rod pressing one of the multiple new bonding materials against the repair area to transfer the new bonding material to the repair area. 
     In addition, the element transfer stamp  200  (see  FIG.  2   ) may also adopt the configuration described in  FIG.  13    to place a new element on a new bonding material. That is, the element transfer stamp  200  may further include: the attachment film described above having multiple new elements, instead of the pads, attached in the form of an array to the lower surface thereof; and a pressing rod pressing one of the multiple new elements against a new bonding material to transfer the new element to the new bonding material. Here, it is obvious that the element transfer stamp  200  may include the load control portion for elements instead of the load control portion for removal  430   c  described above. 
     Although some embodiments have been described herein, it should be understood that these embodiments are provided for illustration only and are not to be construed in any way as limiting the present invention, and that various modifications, changes, alterations, and equivalent embodiments can be made by those skilled in the art without departing from the spirit and scope of the invention. For example, components described as implemented separately may also be implemented in combined form, and vice versa. 
     The scope of the present invention is indicated by the following claims and all changes or modifications derived from the meaning and scope of the claims and equivalents thereto should be construed as being within the scope of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The apparatus for repairing elements according to the present invention is industrially applicable to the field of element repair technology that can prevent damage to a new element during transfer of the new element and can ensure a safe repair process.