Abstract:
An RFID tag including a base including a resin material, an antenna pattern disposed on a surface of the base, and a reinforcement pad disposed on the surface of the base. A thermosetting adhesive is applied onto the antenna pattern and the reinforcement pad, and a circuit chip is electrically coupled to the antenna pattern via the thermosetting adhesive. The reinforcement pad is formed within a region where the circuit chip is mounted, and the circuit chip includes a first protrusion contacting the antenna pattern and a second protrusion contacting the reinforcement pad.

Description:
This application is a divisional of application Ser. No. 11/983,868, filed Nov. 13, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electronic device and a method of manufacturing the same, especially to an electronic device in which a circuit chip is mounted on a film-shaped base body and a method of manufacturing the same. 
     2. Description of the Related Art 
     Conventionally, there has been widely known an electronic device in which a circuit chip is mounted on a base such as a printed circuit board. Such an electronic device is built in an electronic equipment to control the electronic equipment, or used alone to exchange information with external equipment. Such an electronic device includes Radio Frequency Identification (RFID) tags of various kinds that wirelessly exchange information in a non-contact manner with an external device typified by a reader/writer. One type of RFID tag that has been proposed has a structure in which a conductor pattern for radio communication and an IC chip are mounted on a sheet-like base. Applications of such an RFID tag include identification of an article by attaching the RFID tag to the article and thereby exchanging information about the article with external equipment. 
     Incidentally, there is the demand for a more compact and lighter RFID. Specifically, a thinner and more flexible RFID with decreased cost is demanded. In response to such a demand, there has been proposed a RFID tag in which a film formed of a resin material such as polyethylene terephthalate (PET) is used as a base on which an IC chip is mounted (See Japanese Patent Application Laid-open No. 2001-156110, for example). 
       FIG. 10  is a drawing for explaining a conventional method of manufacturing a RFID tag. 
     In Part (a) to Part (d) of  FIG. 10 , each step for manufacturing a RFID tag is sequentially shown. 
     To manufacture a RFID tag, firstly, as shown in Part (a) of  FIG. 10 , a base body  91  composed of a film  911  made of the PET and a conductive pattern  912  formed on the film  911  that functions as an antenna of the RFID tag is prepared, and a thermosetting adhesive  93   p  that hardens by heating is adhered to the base body  91 . 
     Next, as shown in Part (b) of  FIG. 10 , an IC chip  92  is placed on a portion of the base body  91  where the thermosetting adhesive  93   p  is adhered to. On the IC chip  92 , bumps  921  connected to the conductive pattern  912  have been formed. As shown in Part (c) of  FIG. 10 , the IC chip  92  is placed on the base body  91  in such a way that the bumps  921  are aligned with the conductive pattern  912 . 
     Next, as shown in Part (d) of  FIG. 10 , the base body  91  mounted with the IC chip  92  is pinched by a heating device  8  so as to be pressed on the IC chip  92  side (one side of the base body  91  where the IC chip  92  is mounted) and on a film  911  side (the other side of the base body  91  where the film  911  is disposed). The heating device  8  includes a heating head  81  that abuts the IC chip  92  and a heating stage  82  that abuts to support the base body  91 . Then, the thermosetting adhesive  93   p  is hardened through the application of heat by the heating head  81  of the heating device  8 . In this way, the IC chip  92  is fixed to the base body  91  in a state where the bumps  921  contact the conductive pattern  912 , which completes a compact and lightweight RFID tag. 
     However, PET material that forms the film  911  is low in heat resistance as it has the glass transition temperature of about 67° C. Therefore, the film  911  is likely to deform when the thermosetting adhesive  93   p  is heated and hardened. 
       FIG. 11  is a diagram for explaining a state of the base body in the step of heating in Part (d) of  FIG. 10 . 
     As shown in Part (a) of  FIG. 11 , if the processing of heating is executed in a condition where the IC chip  92  is placed on the base body  91 , the temperature of the base body  91  rises and as shown in Part (b) of  FIG. 11 , the film  911  becomes deformed. If the thermosetting adhesive  93   p  in the middle of hardening flows due to the deformation of the film  911 , then air bubbles are generated in the thermosetting adhesive  93   p  and remain as voids  931  after the hardening is completed. As the voids in the solidified thermosetting adhesive  93   p  lowers the adhesion between the IC chip  92  and the base body  91 , the reliability of RFID tags deteriorates. 
     A problem of degraded reliability due to the generation of voids like this is not limited to RFID tags but common to electronic devices in which a circuit chip is mounted on a film-shaped base body. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above circumstances and provides an electronic device with improved reliability by suppressing the generation of voids, and a method of manufacturing the same. 
     A method of manufacturing an electronic device according to the present invention includes the steps of: 
     forming a conductive pattern on a film made of a resin material and thereby forming a base body on which a circuit chip is mounted; 
     forming a reinforcing layer that suppresses expansion and contraction of the film in at least one of a mounting area on the film which area the circuit chip is mounted on and a rear area at the back of the mounting area with the film interposed between the mounting area and the rear area; 
     applying a thermosetting adhesive onto one surface on which the conductive pattern of the base body is formed; 
     mounting the circuit chip that is to be connected to the conductive pattern on the mounting area of the base body via the thermosetting adhesive; 
     pinching the base body mounted with the circuit chip by a heating device that applies heat to the thermosetting adhesive and has a pressing section and a supporting section such that the pressing section abuts the circuit chip mounted on the base body and the supporting section abuts the film and thereby supports the base body; and 
     fixing the circuit chip to the conductive pattern by hardening the thermosetting adhesive through heating by the heating device. 
     Here, the concept that “the reinforcing layer is formed in at least one of a mounting area and a rear area” includes a case in which the reinforcing layer is formed large enough to extend off the mounting area or the rear area. 
     According to the method of manufacturing the electronic device of the present invention, the base body mounted with the circuit chip is pinched between both sides of the heating device, between its pressing section and its supporting section, and the thermosetting adhesive is heated. Since on the film of the base body, the reinforcing layer for suppressing expansion and contraction of this film is formed, it is possible to suppress deformation even if the film is melted by the application of heat. Therefore, the generation of voids associated with the deformation of the film can be suppressed and the reliability of the electronic device can be improved. Also, as manufacturing yield of the electronic device is improved, production cost can be lowered. 
     Here, in the method of manufacturing an electronic device according to the present invention, it is desirable that the step of forming a reinforcing layer is executed in conjunction with the step of forming a conductive pattern in which the reinforcing layer is formed of the same material as the conductive pattern. 
     Since the reinforcing layer is formed of the same material as the conductive pattern and the step of forming a reinforcing layer is executed in conjunction with the step of forming a pattern, it is possible to form the reinforcing layer for suppressing the deformation of film in simplified process. 
     Further, in the method of manufacturing an electronic device according to the present invention, it is desirable that the step of forming a reinforcing layer is a step of forming the reinforcing layer in the mounting area; and the step of mounting is a step of mounting the circuit chip on the base body, the circuit chip having a first protrusion that contacts the conductive pattern and a second protrusion that contacts the reinforcing layer. 
     If the second protrusion provided in the circuit chip contacts the reinforcing layer, and when in the pinching step the base body mounted with the circuit chip is pinched by the heating device, the film is pressed against the supporting section by the reinforcing layer that contacts the circuit chip via the second protrusion. Therefore, the deformation of the film can be surely suppressed. 
     Furthermore, in the method of manufacturing an electronic device according to the present invention, it is desirable that the step of mounting is a step of mounting a circuit chip on the base body, the circuit chip having a plurality of first protrusions that contact the conductive pattern, and the step of forming a reinforcing layer is a step of forming in the rear area the reinforcing layer which has portions corresponding to the plurality of first protrusions. 
     If the reinforcing layer is formed in the rear area and has portions corresponding to the first protrusions, and when in the pinching step the base body mounted with the circuit chip is pinched by the heating device, the film becomes a state of being sandwiched between the conductive pattern that contacts the circuit chip via the first protrusions and the reinforcing layer. Therefore, also in this case, the deformation of the film can be surely suppressed. 
     Moreover, in the method of manufacturing an electronic device according to the present invention, it is desirable that the step of forming a reinforcing layer is a step of forming the reinforcing layer of an insulating material. 
     If the reinforcing layer is formed of an insulating material, it is possible to suppress interference against electromagnetic waves emitted from the conductive pattern and the generation of parasitic capacitance occurring against the conductive pattern. 
     In addition, an electronic device according to the present invention includes: a film made of a resin material; a conductive pattern disposed on the film; a circuit chip mounted on the film and electrically connected to the conductive pattern; and a reinforcing layer to suppress expansion and contraction of the film and is formed in at least one of a mounting area on the film which area the circuit chip is mounted on and a rear area at the back of the mounting area with the film interposed between the mounting area and the rear area. 
     Since the electronic device according to the present invention includes the reinforcing layer which is formed on the film for suppressing expansion and contraction of the film, the deformation of the film can be suppressed at the time of heating the thermosetting adhesive when the base body on which the circuit chip is mounted is pinched from both sides of the base body by the heating device. Therefore, according to the electronic device of the present invention, as voids in the thermosetting adhesive is less, the reliability can be improved. 
     Here, in the electronic device according to the present invention, it is desirable that the reinforcing layer is made of the same material as the conductive pattern and is formed on a surface of the film on which surface the conductive pattern is formed. 
     Additionally, in the electronic device according to the present invention, it is desirable that the reinforcing layer has been formed in the mounting area; and the circuit chip includes a first protrusion that contacts the conductive pattern and a second protrusion that contacts the reinforcing layer. 
     Yet furthermore, in the electronic device according to the present invention, it is desirable that the circuit chip has a first protrusion that contacts the conductive pattern, and the reinforcing layer is formed in the rear area and has a portion corresponding to the first protrusion. 
     Still furthermore, in the electronic device according to the present invention, it is desirable that the reinforcing layer is made of an insulating material. 
     As explained above, according to the present invention, by suppressing the generation of voids, it is possible to realize an electronic device with improved reliability and a method of manufacturing the same. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a mounting surface on which an IC chip of a RFID tag according to a first embodiment of the present invention is mounted. 
         FIG. 2  is a perspective view showing at the backside of the RFID tag according to the first embodiment of the present invention. 
         FIG. 3  is a drawing illustrating process of manufacturing the RFID tag shown in  FIG. 1 . 
         FIG. 4  is a drawing illustrating process of manufacturing the RFID tag following the process shown in  FIG. 3 . 
         FIG. 5  is a drawing illustrating process of manufacturing a RFID tag according to a second embodiment of the present invention. 
         FIG. 6  is a drawing illustrating process of manufacturing a RFID tag according to a third embodiment of the present invention. 
         FIG. 7  is a plan view illustrating a base body formed in the process of forming a conductor shown in Part (a) of  FIG. 6 . 
         FIG. 8  is a plan view illustrating examples of another forms of the RFID tag according to the third embodiment of the present invention. 
         FIG. 9  is a plan view illustrating examples of yet another forms of the RFID tag according to the third embodiment of the present invention. 
         FIG. 10  is a diagram explaining a conventional method of manufacturing a RFID tag. 
         FIG. 11  is a diagram explaining a state of the base body in the heating process in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiments of the present invention will be described below with reference to the accompanying drawings. 
       FIGS. 1 and 2  are perspective views illustrating a RFID tag in the first embodiment of the present invention. FIG.  1  is a perspective view showing a mounting surface  11   a  on which an IC chip of a RFID tag  1  is mounted, and  FIG. 2  is a perspective view showing a backside  11   b  opposite the mounting surface  11   a.    
     The RFID tag  1  shown in  FIGS. 1 and 2  includes a base body  11  composed of a film  111  made of a PET material and a metallic antenna pattern  112  formed on the film  111 ; an IC chip  12  mounted on the base body  11 ; and a thermosetting adhesive  13  for adhering the IC chip  12  to the base body  11 . The IC chip  12  is mounted in a mounting area  11   c  of the mounting surface  11   a  on which the antenna pattern  112  of the base body  11  has been formed, and the IC chip  12  is electrically connected to the antenna pattern  112 . Also, as shown in  FIG. 2 , on the film  111  of the RFID tag  1 , a reinforcing layer  14  is formed over a rear area  11   d  on the back of the mounting area  11   c  (See  FIG. 1 ). In the present embodiment, the reinforcing layer  14  is rectangular, has an area larger than the rear area  11   d  and is made of the same metallic material as the antenna pattern  112 . 
     The RFID tag  1  in the present embodiment is an electronic device for exchanging data in a non-contact manner with a reader writer that is not shown. The RFID tag  1  receives energy of electromagnetic field emitted by the reader writer at the antenna pattern  112  as electric energy, and drives the IC chip  12  with the electric energy. The antenna pattern  112  functions as an antenna for communication, and the IC chip  12  performs radio wave communication via the antenna pattern  112 . 
     Here, the RFID tag  1  corresponds to one example of the electronic device according to the present invention; the antenna pattern  112  corresponds to one example of the conductive pattern according to the present invention; and the IC chip  12  corresponds to one example of the circuit chip according to the present invention. 
     In addition, among those who are skilled in the technical field of the present invention, a “RFID tag” used in the present invention may be called as an “Inlay for RFID tag,” since it is an internal component material for the “RFID tag.” Also this “RFID tag” may be called as a “wireless IC tag.” Additionally, this “RFID tag” also includes an IC card of a non-contact type. 
     Hereinafter, a method of manufacturing this RFID tag  1  will be explained. 
       FIGS. 3 and 4  are drawings illustrating the process of manufacturing the RFID tag shown in  FIG. 1 . 
     In  FIG. 3 , each process of manufacturing the RFID tag  1  is sequentially shown from Part (a) to Part (g), and in  FIG. 4 , each process following the steps in  FIG. 3  is sequentially shown from Part (h) to Part (i). For clarity of drawings, size of the RFID tag  1  in thickness direction and of the IC chip  12  are more exaggerated than those shown in  FIG. 1 . 
     In order to manufacture the RFID tag  1 , firstly, in the process of forming a conductor shown in Part (a) to Part (d) of  FIG. 3 , the antenna pattern  112  is formed on the mounting surface  11   a  of the film  111 . In this process of forming a conductor, the reinforcing layer  14  is formed on the backside  11   b  opposite the mounting surface  11   a . To be more specific, in the process of forming a conductor, firstly, as shown in Part (a) of  FIG. 3 , metallic layers  112   p  and  14   p  made of copper are formed on both sides of the film  111 : an antenna resist layer  115  that has a shape matching that of the antenna pattern is formed on the metallic layer  112   p  at one side of the film  111  directed to the mounting surface  11   a . Next, as shown in Part (b) of  FIG. 3 , a reinforcing resist layer  116  that has a shape matching that of the reinforcing layer  14  is formed on the metallic layer  14   p  directed to the backside  11   b . Then, an etching process is performed for the metallic layers  112   p  and  14   p , and as shown in Part (c) of  FIG. 3 , the antenna pattern  112  and the reinforcing layer  14  are formed. Next, the antenna resist layer  115  and the reinforcing resist layer  116  are removed. Thereby, as shown in Part (d) of  FIG. 3 , the base body  11  in which the antenna pattern  112  and the reinforcing layer  14  have been formed on the film  111  can be obtained. In the process described later, of the base body  11 , the IC chip  12  will be mounted in the mounting area  11   c  of the mounting surface  11   a  on which the antenna pattern  112  has been formed. Additionally, the reinforcing layer  14  that suppresses expansion and contraction of the film  111  is formed on the rear area  11   d  opposite the mounting area  11   c  with the film  111  interposed between the mounting area  11   c  and the rear area  11   d . In the present embodiment, the reinforcing layer  14  has been formed larger than the rear area  11   d.    
     Here, the process of forming a conductor shown in Part (a) to Part (d) of  FIG. 3  corresponds to each example of the step of forming a conductive pattern and the step of forming a reinforcing layer according to the present invention, and in this process of forming a conductor, the process corresponding to the step of forming a conductive pattern and the step of forming a reinforcing layer are executed simultaneously. 
     Next, in the adhering process shown in Part (e) of  FIG. 3 , a liquid thermosetting adhesive  13   p  is adhered onto the base body  11 . The thermosetting adhesive  13   p  is pasted on the mounting area  11   c  and its surrounding area of the mounting area  11   a  of the base body  11  on which the IC chip  12  will be mounted (See Part (d)). 
     Next, in the mounting process shown in Part (f) to Part (g) of  FIG. 3 , the IC chip  12  is placed on the mounting area  11   c . The IC chip  12  is placed on the base body  11  by a flip-chip technique. That is, the IC chip  12  is placed on the base body  11  via the thermosetting adhesive  13   p  in such a way that a surface  12   a  on which the circuit has been formed faces the base body  11 . On the surface  12   a  on which the circuit of the IC chip  12  has been formed, bumps  121  that are to be connected to the antenna pattern  112  is formed. As shown in Part (f) of  FIG. 3 , the IC chip  12  is placed on the base body  11  in such a way that the bumps  121  are aligned with the antenna pattern  112 . 
     Next, in pinching process shown in Part (h) of  FIG. 4 , the base body  11  on which the IC chip  12  has been placed is pinched by a heating device  2  that includes a heating head  21  and a heating stage  22  such that the heating head  21  abuts the IC chip  12  and the heating stage  22  abuts to support the base body  11  on which the IC chip  12  has been placed. In other words, the base body  11  is held between the heating head  21  and heating stage  22 . To be more specific, the heating stage  22  abuts the reinforcing layer  14  disposed at the backside  11   b  of the base body  11 . In addition, the heating head  21  includes a built-in heater that is not shown. The pinching process shown in Part (h) of  FIG. 4  causes the bumps  121  to surely contact the antenna pattern  112 . 
     Also, as the reinforcing layer  14  of the present embodiment has been formed larger than the rear area  11   d  (See Part (d) of  FIG. 3 ), the reinforcing layer  14  includes the portions (positions) corresponding to the bumps  121 . Because of this, by the pinching process shown in Part (h) of  FIG. 4 , a state is brought about in which the film  111  is interposed between the antenna pattern  112  that contacts the IC chip  12  via the bumps  121  and the reinforcing layer  14  that is formed opposed to the bumps  121  and includes the portions corresponding to the bumps  121 . 
     Next, in the heating process shown in Part (i) of  FIG. 4 , the heating head  21  is heated to harden the thermosetting adhesive  13   p  by the heating. By hardening the thermosetting adhesive  13   p , the bumps  121  are fixed to the base body  11  in such a state where the bumps  121  contacts the antenna pattern  112 . Since the reinforcing layer  14  that suppresses expansion and contraction of the film  111  has been formed on the rear area  11   d  at the backside of the mounting area  11   c  where the IC chip  12  will be mounted, even though the film  111  melts by the heating, deformation of the film  111  can be suppressed. Moreover, since the film  111  is sandwiched between the antenna pattern  112  in contact with the IC chip  12  via the bumps  121  and the reinforcing layer  14  that is formed opposed to the bumps  121  and includes the portions corresponding to the bumps  121 , expansion and contraction of the film  111  can be further suppressed. As a result of this, it is possible to suppress generation of voids in the thermosetting adhesive  13   p  accompanying the deformation of the film. 
     When heating process in Part (i) of  FIG. 4  finishes, the RFID tag  1  (See  FIG. 1 ) is completed. 
     The heating device  2  corresponds to one example of the manufacturing device of the electronic device in the present invention; the heating head  21  corresponds to a combination of one example of the pressing section and one example of the heating section; and the heating stage  22  corresponds to one example of the supporting section of the present invention. 
     Next, an explanation will be made for the second embodiment of the present invention in which materials of the reinforcing layer are different from those in the first embodiment. In the second embodiment described below, the explanation will focus on the features different from the first embodiment, by utilizing the drawings referred to in the explanation of the first embodiment. 
     Since the RFID tag of the second embodiment has the same appearance as the RFID tag  1  shown in  FIGS. 1 and 2 , in the following, the RFID tag of the second embodiment will be explained by utilizing  FIGS. 1 and 2 . In the RFID tag of the second embodiment, the reinforcing layer is formed of an insulating material, which is different from the RFID tag of the first embodiment. Because of this, the RFID tag of the second embodiment does not hinder electromagnetic waves emitted from the antenna pattern  112 . In addition, it is possible to adopt ceramics and resign as a material of the reinforcing layer  14 . 
       FIG. 5  is a drawing illustrating process of manufacturing the RFID tag of the second embodiment according to the present invention. 
     The process of manufacturing a RFID tag of the second embodiment is different from that of the first embodiment shown in  FIG. 3  in that in the process of forming a conductor shown in Part (a) to Part (d) of  FIG. 3 , only the antenna pattern  112  is formed whereas the reinforcing layer  14  is not formed. In the step of manufacturing a RFID tag of the second embodiment, after the antenna pattern  112  has been formed, as shown in Part (a) of  FIG. 5 , an adhesive  15  is pasted on a sheet  14   a  made of an insulating material. Then, as shown in Part (b) of  FIG. 5 , the sheet  14   a  is attached to the backside of the film  111 , which is then adhered tightly by pinching with a pressing device  24  to form the reinforcing layer. After this, the same steps as shown in Part (e) of  FIG. 3  to  FIG. 4  are executed to obtain the RFID tag of the second embodiment. The press shown in Part (b) of  FIG. 5  in which the sheet  14   a  is attached corresponds to one example of the step of forming a reinforcing layer according to the present invention. 
     Next, an explanation will be made about the third embodiment of the present invention, focusing the differences between the third embodiment and the first and second embodiments, using the same reference characters as in the first embodiment for the common configuration with the first embodiment. 
       FIG. 6  is a drawing illustrating the process of manufacturing the RFID tag of the third embodiment according to the present invention. 
     In  FIG. 6 , each process of manufacturing the RFID tag of the third embodiment is sequentially shown from Part (a) to Part (e). 
     The RFID tag of the third embodiment has almost the same appearance as the RFID tag  1  of the first embodiment shown in  FIG. 1 . The RFID tag of the third embodiment is, however, different from the RFID tag  1  of the first embodiment in that the reinforcing layer is formed in the mounting area  11   c , not on the rear area  11   d  (See  FIG. 2 ). 
     In order to manufacture the RFID tag of the third embodiment, firstly, in the process of forming a conductor shown in Part (a) of  FIG. 6 , the antenna pattern  112  and a reinforcing layer  43  made of the same copper are formed simultaneously on the mounting surface  11   a  of the film  111 . 
       FIG. 7  is a plan view illustrating a base body formed in the step of forming a conductor shown in Part (a) of  FIG. 6 . 
     As shown in  FIG. 7 , in the base body  41 , the antenna pattern  112  and the reinforcing layer  43  are formed on the mounting surface  11   a  of the film  111 . The reinforcing layer  43  is formed into a cruciform in a mounting area  11   c  on which an IC chip  42  is mounted. 
     The explanation continues by returning to  FIG. 6 . Next, in the adhering process shown in Part (b) of  FIG. 6 , the thermosetting adhesive  13   p  is adhered to the mounting area  11   c  and its surrounding area of the base body  41 , then in the mounting process shown in Part (b) and Part (c) of  FIG. 6 , the IC chip  42  is placed on the mounting area  11   c  of the base body  41 . On the IC chip  42 , in addition to the bumps  121  that have been formed on a surface  12   a  on which the circuit has been formed and that connects to the antenna pattern  112 , a dummy bump  422  that contacts the reinforcing layer  43  is formed. Although the reinforcing layer  43  and the dummy bump  422  do not possess any electrical function, they may be connected to the ground potential of the IC chip  42  in order to avoid, for example, a state of electrical floating. 
     Next, in pinching process shown in Part (e) of  FIG. 6 , the base body  41  on which the IC chip  42  has been mounted is pinched by the heating device  2 . The film  111  is brought into a state of being held between the reinforcing layer  43  in contact with the IC chip  42  via the dummy bump  422  and the heating stage  22 . 
     Next, in the heating process shown in Part (f) of  FIG. 6 , the heating head  21  is heated to harden the thermosetting adhesive  13   p  by the heating. By hardening the thermosetting adhesive  13   p , the IC chip  42  is fixed to the base body  41  in a state where the bumps  121  is in contact with the antenna pattern  112 . 
     Since the reinforcing layer  43  has been formed on the mounting area  11   c  on the film  111 , it is possible to suppress expansion and contraction of the film  111 . Therefore, even though the film  111  melts by heating, the deformation of the film  111  can be suppressed. Moreover, since the film  111  is sandwiched between the reinforcing layer  43  in contact with the IC chip  42  via the dummy bump  422  and the heating stage  22 , expansion and contraction of the film  111  can be suppressed more effectively. As a result of this, it is possible to suppress generation of voids in the thermosetting adhesive  13   p  accompanying the deformation of the film. 
     As described above, the explanation has been made about the third embodiment. Hereafter, variations of the third embodiment will be described, which are different from the third embodiment in their shape and placement of the antenna pattern and the reinforcing layer  43 . 
       FIGS. 8 and 9  are plan views illustrating variations of the RFID tag of the third embodiment according to the present invention. 
     In  FIGS. 8 and 9 , the base body  41  is shown, in which the IC chip is removed from the RFID tag. Part (a) to Part (g) of  FIG. 8 , similar to  FIG. 7 , show seven examples in each of which two antenna patterns  112  are formed. Further, Part (a) to Part (e) of  FIG. 9  show five examples in each of which four antenna patterns  112  are formed. 
     A reinforcing layer  43   a  shown in Part (a) of  FIG. 8  is shaped like letter H; a reinforcing layer  43   b  shown in Part (b) is circular; a reinforcing layer  43   c  shown in Part (c) is two straight lines extending parallel to the direction the antenna pattern  112  extends; reinforcing layers  43   d  and  43   g  shown in Part (d) and Part (g) are straight lines perpendicular to the direction the antenna pattern  112  extends; a reinforcing layer  43   e  shown in Part (e) is shaped like letter X; and a reinforcing layer  43   f  shown in Part (f) is three straight lines extending parallel to the direction the antenna pattern  112  extends. 
     Furthermore, reinforcing layers  43   h  and  43   k  shown in Part (a) and Part (d) of  FIG. 9  are cruciform; a reinforcing layer  43   i  shown in Part (b) is octagon; a reinforcing layer  43   j  shown in Part (c) is rectangular; and a reinforcing layer  43   m  shown in Part (e) is circular. 
     Although the reinforcing layers  43   a  to  43   m  are formed in the mounting area  11   c , these layers may be formed by their part extending off the mounting area  11   c , as shown in Part (g) of  FIG. 8  and Part (d) of  FIG. 9 . 
     Additionally, although in the above-described embodiments, descriptions are made on the method of manufacturing the RFID tag and the heating device. The present invention is, however, not limited to a RFID tag and may be also applied to a method of manufacturing any other electronic device in which a circuit chip is mounted on a film-like base. For example, the present invention may be employed to a manufacturing method of an ultrathin IC card, or a printed circuit board in which a circuit chip is fixed to a flexible printed circuit (FPC) as a base with a thermoset adhesive. 
     Still more, in the above-described embodiments, the film composing the base section of the RFID tag is made of a PET material. However, the film of the electronic device according to the present invention is not limited to the PET material, and may be made of materials selected from a polyester material, a polyolefin material, a polycarbonate material, an acrylic material and so on. 
     Moreover, in the above-described embodiments, the heating head corresponds to an example of the pressing section according to the present invention and serves as a heater, whereas the heating stage does not have function of heating. The present invention, however, is not limited to this, and it is also possible to provide the supporting section with heating function and to provide a heating section as another section, separately from the heating stage and heating head.