Patent Publication Number: US-2021175142-A1

Title: Integrated circuit (ic) tag

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2019-219678, filed on Dec. 4, 2019, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to an integrated circuit (IC) tag. 
     BACKGROUND 
     Conventionally, there is a circuit substrate in which a cover lay is provided on the top of copper foil wiring on the upper surface of the substrate and the upper surface of the substrate, and an IC chip is connected on the top of the cover lay via an anisotropic conductive film. A terminal of the IC chip and the wiring is electrically connected by the anisotropic conductive film. 
     Examples of the related art include Japanese Laid-open Patent Publication No. 2002-076059. 
     SUMMARY 
     According to an aspect of the embodiments, an integrated circuit (IC) tag includes: an IC chip; a substrate that is provided with an antenna on a first surface; an adhesive portion configured to adhere a side surface of the IC chip and a peripheral of the IC chip in a state that a terminal of the IC chip is electrically coupled to the antenna; and a first member that is provided between the antenna and the adhesive portion, the first member having an elastic modulus higher than an elastic modulus of the antenna. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating an IC tag  100  according to a first embodiment; 
         FIG. 2  is a diagram illustrating a cross-section taken along line A-A in  FIG. 1  as viewed in the arrow direction; 
         FIG. 3  is a diagram illustrating a state in which a crack  130 B is produced in an adhesive portion  130 ; 
         FIG. 4  is a diagram illustrating an IC tag  10  of a comparative example; 
         FIG. 5  is a diagram illustrating a cross-section taken along line B-B in  FIG. 4 ; 
         FIG. 6  is a diagram illustrating an IC tag  200  according to a second embodiment; 
         FIG. 7  is a diagram illustrating a cross-section taken along line C-C in  FIG. 6  as viewed in the arrow direction; and 
         FIG. 8  is a diagram illustrating a part of the process of manufacturing the IC tag  200  according to the second embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     Incidentally, IC tags are attached to various articles and are sometimes subjected to stress due to impact or the like as the articles are moved. For this reason, the IC tags are supposed to have a strong structure so as not to be damaged by stress. 
     In such a case, if an adhesive portion is provided between the side surface of the IC tag and the substrate to ensure the strength, the adhesive portion is made thicker, and there is a possibility that an antenna is damaged (disconnected) when a crack is produced in the adhesive portion due to impact and reaches the antenna. For example, if the antenna is damaged, the IC tag can no longer perform communication. 
     According to an aspect of the embodiments, provided is an IC tag capable of suppressing damage to an antenna even when used in an environment where stress is likely to be imparted. 
     Hereinafter, exemplary modes to which IC tags of the present embodiments are applied will be described. 
     First Embodiment 
       FIG. 1  is a diagram illustrating an IC tag  100  according to a first embodiment.  FIG. 2  is a diagram illustrating a cross-section taken along line A-A in  FIG. 1  as viewed in the arrow direction. Hereinafter, description will be given using an XYZ coordinate system. The plan view means to view in the XY plane. Furthermore, for convenience of explanation, the +Z direction side is referred to as the upper side and the −Z direction side is referred to as the lower side, but these directions do not represent a general upper-lower relationship. 
     The IC tag  100  is a radio frequency identifier (RFID) tag including a substrate  110 , an IC chip  120 , an adhesive portion  130 , and a cover  140 . For example, the IC tag  100  is attached to linen such as sheets or towels, and is used to identify each piece of linen. As an example, linen is washed and repeatedly used, and the washing is sometimes performed in a large industrial washing machine. When washed with such a washing machine, the linen is subjected to very large pressure, pulling force, and the like, and accordingly a very large stress is imparted to the IC tag  100  from various directions. Therefore, the IC tag  100  is expected to have a structure capable of withstanding such a very large stress. 
     Note that, as an example, the size of the IC chip  120  in plan view is 0.5 mm×0.5 mm, and as an example, the thickness (in the Z direction) is 0.22 mm. The dimensions of the IC tag  100  are 54 mm×5 mm in plan view, and as an example, the thickness (in the Z direction) is 0.5 mm. 
     The substrate  110  is made with, for example, polyethylene terephthalate (PET), and has a rectangular shape in plan view. An antenna  111  and a resist  112  are provided on an upper surface of the substrate  110 . The upper surface of the substrate  110  is an example of a first surface. Although the antenna  111  is illustrated as a planar antenna as an example, the antenna  111  may be patterned in various shapes in plan view, depending on the usage of the IC tag  100 , the communication frequency, and the like. The antenna  111  is implemented by, for example, a silver paste (Ag paste) applied on the upper surface of the substrate  110 . The antenna  111  made with the Ag paste is softer (lower in elastic modulus) than the resist  112 . 
     The resist  112  is formed on the top of a part of the upper surface of the substrate  110  and a part of an upper surface of the antenna  111 . As the material of the resist  112 , an insulating material for resist used for insulating wiring such as a wiring substrate can be used. The resist  112  is softer (lower in elastic modulus) than the thermosetting adhesive portion  130 . 
     The resist  112  has an opening  112 A having a rectangular shape at a center in plan view. An inside of the opening  112 A is an area where the resist  112  is not provided. A part of the antenna  111  on a center side in the X direction is exposed at the opening  112 A, The length of the opening  112 A in the X direction is longer than the length of the IC chip  120  in the X direction in the cross-sectional view illustrated in  FIG. 2 , and is smaller than the length between two sections of a lower end  130 A located on opposite sides of the adhesive portion  130  in the X direction. The lower end  130 A corresponds to a position on an outermost side in plan view in an area where the adhesive portion  130  contacts the resist  112 . This is because the adhesive portion  130  is inclined so as to extend outward from the upper side to the lower side in a cross-sectional view. Note that such a configuration similarly applies to a cross-section along the Y direction. 
     The IC chip  120  is a chip that incorporates an IC having an internal memory that stores a unique ID, and has four terminals  121  on a lower surface. The terminal  121  is electrically connected to the antenna  111  via the adhesive portion  130 , and operates with the electric power received via the antenna  111  to radiate a signal that contains the ID, via the antenna  111 . The signal that contains the ID is received by a reader. The IC tag  100  is a passive RFID tag that does not include a power supply. 
     The adhesive portion  130  is, for example, a member obtained by curing an adhesive agent that exhibits anisotropic conductivity, and adheres a part of a side surface of the IC chip  120 , a part of the antenna  111 , and a part of the resist  112 , while having conductivity that electrically connects the terminals  121  and the antenna  111  on the lower surface of the IC chip  120 . 
     An adhesive agent that exhibits anisotropic conductivity and implements the adhesive portion  130  is a mixture obtained by mixing conductive particles in a binder made with thermosetting resin, and when heated while pressure is imparted in the upper-lower direction (thermocompression bonding), undergoes thermosetting to adhere the terminals  121  and the antenna  111 , and also to electrically connect the terminals  121  and the antenna  111  in the upper-lower direction. Furthermore, the adhesive agent that exhibits anisotropic conductivity and implements the adhesive portion  130  adheres a part of the side surface of the IC chip  120 , a part of the antenna  111 , and a part of the resist  112 . 
     The lower end  130 A of the adhesive portion  130  is circular in plan view, and the length between sections of the lower end  130 A located on opposite sides of the adhesive portion  130  in the X direction is longer than the length of the opening  112 A of the resist  112  in the X direction. 
     For example, the lower end  130 A located at a position on the outermost side in plan view in the X direction in an area where the adhesive portion  130  contacts the resist  112  is located outside the position of an opening end of the opening  112 A in plan view. Furthermore, the antenna  111  extends to the inside of the resist  112  in the X direction, and an end of the antenna  111  on the center side in the X direction is located on the lower side of the IC chip  120 . Note that this similarly applies to the Y direction. 
     Therefore, in a peripheral portion of the IC chip  120  on the upper surface of the substrate  110 , there are areas where the antenna  111 , the resist  112 , and the adhesive portion  130  are laminated in this order (areas indicated by two dashed ellipses in  FIG. 2 ). Note that, the peripheral portion of the IC chip  120  denotes an area located around the IC chip  120  in a rectangular region defined by the upper surface of the substrate  110  in plan view. 
     The cover  140  covers the resist  112 , the upper surface and an upper side part of the side surface of the IC chip  120 , and the adhesive portion  130 , on the upper surface of the substrate  110 . The cover  140  is provided to protect the IC chip  120  and a connecting portion between the IC chip  120  and the antenna  111  from an impact or the like. The size of the cover  140  in plan view is smaller than the substrate  110  as an example, and ends of the antenna  111  on the ±X direction side and ends of the resist  112  on the ±X direction side and the ±Y direction side in plan view are not covered by the cover  140 . Note that the cover  140  may be configured to cover the ends of the antenna  111  on the ±X direction side and ends of the resist  112  on the ±X direction side and ±Y direction side in plan view. 
     The cover  140  is a resin potting made with urethane resin, which is obtained by curing a main agent and a curing agent through chemical reaction. Since the resin potting has elasticity and is easily deformed, it is suitable for the cover of the IC tag  100  to which stress is imparted from various directions. Note that the cover  140  may be made with a material other than potting resin as long as the material has elasticity and is easily deformed. 
       FIG. 3  is a diagram illustrating a state in which a crack  1308  is produced in the adhesive portion  130 . It is assumed that stress is imparted to the IC tag  100  and a crack  130 B is produced in an area of the adhesive portion  130  located on a side surface side of the IC chip  120 . However, since the resist  112  that is softer and easier to deform than the adhesive portion  130  is provided between the antenna  111  and the adhesive portion  130 , the crack  130 B is not caused in the resist  112 , and the resist  112  elastically deforms to absorb or relax the stress imparted to the adhesive portion  130 ; damaging the antenna  111  is thus suppressed. 
     In this manner, even if the crack  130 B produced in an area of the adhesive portion  130  located on a side surface side (a side surface side on the X direction side) of the IC chip  120 , damage to the antenna  111  may be suppressed. 
       FIG. 4  is a diagram illustrating an IC tag  10  of a comparative example.  FIG. 5  is a diagram illustrating a cross-section taken along line B-B in  FIG. 4 . Among components of the IC tag  10  of the comparative example, components similar to the components of the IC tag  100  of the first embodiment are designated by the same reference signs, and the description thereof will be omitted. 
     The IC tag  10  is an RFID tag including a substrate an IC chip  120 , an adhesive portion  13 , and a cover  140 . 
     Similar to the substrate  110 , the substrate  11  is made with PET, and has a rectangular shape in plan view. An antenna  111  and a resist  12  are provided on an upper surface of the substrate  11 . The substrate  11  is different from the substrate  110  of the first embodiment in that an opening  12 A of the resist  12  is larger and has a circular shape, and the resist  12  and the adhesive portion  13  have no overlapping area. 
     When stress is imparted to the IC tag  10 , and a crack  13 A is produced in an area of the adhesive portion  13  located on a side surface side (a side surface side on the X direction side) of the IC chip  120 , the crack  13 A reaches the antenna  111 , and accordingly there is a possibility that the antenna  111  is disconnected. 
     In contrast to this, the IC tag  100  of the first embodiment has areas where the antenna  111 , the resist  112 , and the adhesive portion  130  are laminated in this order (areas indicated by two dashed ellipses in  FIG. 2 ), in the peripheral portion of the IC chip  120  on the upper surface of the substrate  110 . 
     Therefore, even if the crack  1308  (see  FIG. 3 ) is produced in an area of the adhesive portion  130  located on a side surface side (a side surface side on the X direction side) of the IC chip  120 , the crack  1308  reaches only the resist  112 , and accordingly damage to the antenna  111  may be suppressed. 
     Consequently, the IC tag  100  capable of suppressing damage to the antenna  111  even when used in an environment where stress is likely to be imparted may be provided. 
     Second Embodiment 
       FIG. 6  is a diagram illustrating an IC tag  200  according to a second embodiment.  FIG. 7  is a diagram illustrating a cross-section taken along line C-C in  FIG. 6  as viewed in the arrow direction. Hereinafter, description will be given using an XYZ coordinate system. The plan view means to view in the XY plane. Furthermore, for convenience of explanation, the +Z direction side is referred to as the upper side and the −Z direction side is referred to as the lower side, but these directions do not represent a general upper-lower relationship. In addition, in the following, components similar to the components of the IC tag  100  of the first embodiment are designated by the same reference signs, and the description thereof will be omitted. 
     The IC tag  200  is an RFID tag including a substrate  210 , an IC chip  120 , an adhesive portion  230 , a cover  240 , and an elastic member  250 . Similar to the IC tag  100  of the first embodiment, for example, the IC tag  200  is attached to linen such as sheets or towels, and is used to identify each piece of linen. 
     The substrate  210  is made with PET, for example, and has a rectangular shape in plan view. An antenna  111  and a resist  212  are provided on an upper surface of the substrate  210 . The upper surface of the substrate  210  is an example of the first surface. 
     The resist  212  is formed on the top of a part of the upper surface of the substrate  210  and a part of an upper surface of the antenna  111 . As the material of the resist  212 , an insulating material for resist used for insulating wiring such as a wiring substrate can be used. 
     The resist  212  has a large opening  212 A having a circular shape at a center in plan view. The opening  212 A is similar to the opening  12 A (see  FIG. 4 ) of the resist  12  of the IC tag  10  of the comparative example. 
     The adhesive portion  230  is, for example, a member obtained by curing an adhesive agent that exhibits anisotropic conductivity, and has a connecting portion  231  and a side surface adhesive portion  232 . 
     The connecting portion  231  adheres a lower surface of the IC chip  120  to the upper surface of the substrate  210  and the antenna  111 , and also electrically connects terminals  121  of the IC chip  120  and the antenna  111 . The side surface adhesive portion  232  is adhered to a side surface of the IC chip  120 , and adheres the side surface of the IC chip  120  and an upper surface of the elastic member  250 . An adhesive agent that exhibits anisotropic conductivity and implements the adhesive portion  230  is similar to the adhesive agent that exhibits anisotropic conductivity and implements the adhesive portion  130  of the first embodiment. 
     A lower end  230 A of the adhesive portion  230  is circular in plan view; a circular shape formed by sections of the lower end  230 A located on opposite sides of the adhesive portion  230  in the X direction is smaller than the circular shape of the opening  212 A of the resist  212 , and is located inside the circular shape of the opening  212 A of the resist  212 . 
     The cover  240  covers a part of the resist  212 , the upper surface and an upper side part of the side surface of the IC chip  120 , the side surface adhesive portion  232  of the adhesive portion  230 , and a part of the elastic member  250 , on the upper surface of the substrate  210 . Similar to the cover  140  of the first embodiment, the cover  240  is provided to protect the antenna  111 , the IC chip  120 , and a connecting portion between the IC chip  120  and the antenna  111  from an impact or the like, and is implemented by similar resin potting 
     The elastic member  250  is provided between the antenna  111  and the side surface adhesive portion  232 , and has a higher elastic modulus than the antenna  111 . Since the antenna  111  made with Ag paste is softer than the resist  212  (lower in elastic modulus), the elastic member  250  is supposed to be harder than the antenna  111  and softer than the resist  212 . 
     Making the elastic modulus of the elastic member  250  higher than the elastic modulus of the antenna  111  is to protect the antenna  111  in a case where stress to an extent to cause a crack is imparted to the side surface adhesive portion  232 , by providing a member softer than the resist  212  between the side surface adhesive portion  232  and the antenna  111 . 
     Furthermore, the elastic modulus of the elastic member  250  is an elastic modulus lower than the elastic modulus of the resist  212 , or an elastic modulus that allows the terminals  121  of the IC chip  120  and an adhesive agent for the adhesive portion  230  before being thermoset to break through and penetrate the elastic member  250  when the IC chip  120  is pushed from the upper side in the course of manufacturing. Allowing the terminals  121  and the adhesive agent for the adhesive portion  230  before being thermoset to break through and penetrate the elastic member  250  means that, when the IC chip  120  placed on the adhesive agent for the adhesive portion  230  before being thermoset is pushed against the elastic member  250  to flatten and deform the elastic member  250 , a hole is opened at least only in an area where the terminals  121  and the adhesive agent for the adhesive portion  230  before being thermoset overlap each other and are in touch with the elastic member  250 , and an area near the hole is kept in an unified state. 
     In this manner, implementing the elastic modulus of the elastic member  250  as an elastic modulus that allows the terminals  121  of the IC chip  120  and the adhesive agent for the adhesive portion  230  before being thermoset to break through and penetrate the elastic member  250  when the IC chip  120  is pushed from the upper side in the course of manufacturing is enabled when the elastic modulus of the elastic member  250  is lower than the elastic modulus of the resist  212 . In addition, when a resist similar to the resist  212  is used instead of the elastic member  250 , the terminals  121  of the IC chip  120  and the adhesive agent for the adhesive portion  230  before being thermoset has not been allowed to break through the resist. 
     Therefore, the elastic modulus of the elastic member  250  is employed as an elastic modulus lower than the elastic modulus of the resist  212 , or an elastic modulus that allows the terminals  121  of the IC chip  120  to break through and penetrate the elastic member  250  when the IC chip  120  is pushed from the upper side in the course of manufacturing. 
     As such an elastic member  250 , for example, polypropylene-based resin or the like can be used. 
     The elastic member  250  is provided in the peripheral portion of the IC chip  120  on the upper surface of the substrate  210 , between the antenna  111  and the side surface adhesive portion  232 . The elastic modulus of the elastic member  250  is an elastic modulus higher than the elastic modulus of the antenna  111  and lower than the elastic modulus of the resist  212 , or an elastic modulus that allows the terminals  121  of the IC chip  120  and an adhesive agent for the adhesive portion  230  before being thermoset to break through and penetrate the elastic member  250  when the IC chip  120  is pushed from the upper side in the course of manufacturing. Therefore, the elastic member  250  is easier to deform than the resist  212  and harder to deform than the antenna  111 . For this reason, even if stress is imparted to the IC tag  200  and a crack is produced in the side surface adhesive portion  232 , the elastic member  250  is deformed to absorb or relax the stress and protect the antenna  111 , thereby being able to suppress damage to the antenna  111 . 
     Furthermore, the elastic member  250  is in contact with the side surface of the IC chip  120 . Therefore, the stress may be effectively absorbed between the side surface adhesive portion  232  and the antenna  111 . 
       FIG. 8  is a diagram illustrating a part of the process of manufacturing the IC tag  200  according to the second embodiment. At a center portion of the upper surface of the substrate  210 , the elastic member  250  and an adhesive agent  230 C for the adhesive portion  230  are arranged in an overlapping manner, and when the IC chip  120  is pressed against the adhesive agent  230 C in the −Z direction, the terminals  121  of the IC chip  120  and the adhesive agent  230 C break through the elastic member  250  and then are positioned on the top of the antenna  111 . 
     When the adhesive agent  230 C is heated in this state, the adhesive agent  230 C is separated into the connecting portion  231  and the side surface adhesive portion  232  as illustrated in  FIG. 7 , and the connecting portion  231  and the side surface adhesive portion  232  are cured on the lower surface and the side surface of the IC chip  120 , respectively. Here, it does not matter whether a portion that connects the connecting portion  231  and the side surface adhesive portion  232  remains or no longer remains. 
     Since the connecting portion  231  has conductivity in the pressed direction, the terminals  121  of the IC chip  120  on the lower surface and the antenna  111  are electrically connected. Thereafter, the cover  240  can be formed. 
     Accordingly, even if stress is imparted to the IC tag  200  and a crack is produced in the side surface adhesive portion  232  in the adhesive portion  230 , the elastic member  250  is deformed to absorb or relax the stress and protect the antenna  111 , thereby being able to suppress damage to the antenna  111 . 
     Consequently, the IC tag  200  capable of suppressing damage to the antenna even when used in an environment where stress is likely to be imparted may be provided. 
     Furthermore, the elastic member  250  is in contact with the side surface of the IC chip  120 . Therefore, the stress may be effectively absorbed between the side surface adhesive portion  232  and the antenna  111 , and even if a crack is produced in the side surface adhesive portion  232 , damage to the antenna  111  may be suppressed. 
     All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.