Patent Publication Number: US-2007094870-A1

Title: Wiring board, method of manufacturing the same, semiconductor device, and electronic instrument

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a divisional of U.S. patent application Ser. No. 10/791,651 filed on Mar. 2, 2004. This application claims the benefit of Japanese Patent Application No. 2003-55643, filed on Mar. 3, 2003, and Japanese Patent Application No. 2003-55644, filed on Mar. 3, 2003. The disclosures of the above applications are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      The present invention relates to a wiring board, a method of manufacturing the same, a semiconductor device, and an electronic instrument.  
      Conventionally, a printed circuit board is manufactured by attaching copper foil to a base material and forming interconnects by etching. This complicates the process and makes it necessary to use an expensive mask for etching. Moreover, a number of pieces of equipment is necessary. A polyimide is generally used as the base material. However, since adhesion between the polyimides is low, it is difficult to manufacture a multilayer substrate.  
      In recent years, a technology of forming interconnects by ejecting metallic ink onto a surface-treated base material has been developed. In the case of controlling the surface tension of the metallic ink by forming a fluorine film on the base material (fluoroalkylsilane (FAS) treatment) and making the fluorine film porous as the surface treatment, it is difficult to increase adhesion between the interconnect and the base material. Moreover, interlayer separation easily occurs after stacking the base materials, whereby it is difficult to manufacture a highly reliable multilayer substrate. Furthermore, since the fluorine films cannot be stacked, a stacked structure may not be obtained.  
      As the surface treatment, a method of forming a receiving layer having swelling properties by applying a polyvinyl alcohol to the base material, or a method of forming a (porous) receiving layer having voids by applying aluminum hydroxide to the base material may be employed. However, since the receiving layer tends to contain moisture due to high hygroscopicity, the receiving layer is not suitable as an inner layer or an inner layer of the multilayer substrate. Moreover, it is difficult to increase adhesion between the interconnect and the base material. Since it is difficult to increase adhesion between the interconnect and the base material, interlayer separation easily occurs after stacking the base materials. Therefore, it is difficult to manufacture a highly reliable multilayer substrate.  
     BRIEF SUMMARY OF THE INVENTION  
      A method of manufacturing a wiring board according to one aspect of the present invention includes:  
      softening a receiving layer formed of a thermoplastic resin by applying heat;  
      forming an interconnect layer on the receiving layer which is softened by the application of heat using a solvent containing conductive particles; and  
      causing the conductive particles to be bonded together by heating the interconnect layer.  
      A method of manufacturing a wiring board according to another aspect of the present invention includes:  
      forming a first interconnect layer on a first receiving layer formed of a thermoplastic resin which has been in a softened state by using a solvent containing conductive particles;  
      forming a second receiving layer in a softened state on the first receiving layer and the first interconnect layer by using a thermoplastic resin;  
      forming a second interconnect layer on the second receiving layer which has been in the softened state by using a solvent containing conductive particles; and  
      causing the thermoplastic resins of the first and second receiving layers to be softened and the conductive particles to be bonded together in a connecting portion of the first and second interconnect layers by applying heat.  
      A wiring board according to a further aspect of the present invention is manufactured by one of the above methods.  
      A semiconductor device according to a still further aspect of the present invention includes:  
      the above wiring board; and  
      a semiconductor chip electrically connected with the wiring board.  
      An electronic instrument according to a yet further aspect of the present invention includes the above semiconductor device. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       FIGS. 1A  to  1 D are illustrative of a method of manufacturing a wiring board according to a first embodiment of the present invention.  
       FIGS. 2A  to  2 C are illustrative of a method of manufacturing a wiring board according to the first embodiment of the present invention.  
       FIGS. 3A and 3B  are illustrative of a method of manufacturing a wiring board according to the first embodiment of the present invention.  
       FIGS. 4A  to  4 D are illustrative of a method of manufacturing a wiring board according to a second embodiment of the present invention.  
       FIGS. 5A  to  5 C are illustrative of a wiring board according to a third embodiment of the present invention.  
       FIGS. 6A  to  6 D are illustrative of a method of manufacturing a wiring board according to a fourth embodiment of the present invention.  
       FIGS. 7A  to  7 C are illustrative of a method of manufacturing a wiring board according to the fourth embodiment of the present invention.  
       FIGS. 8A  to  8 C are illustrative of a method of manufacturing a wiring board according to the fourth embodiment of the present invention.  
       FIGS. 9A and 9B  are illustrative of a method of manufacturing a wiring board according to the fourth embodiment of the present invention.  
       FIGS. 10A  to  10 C are illustrative of a method of manufacturing a wiring board according to a fifth embodiment of the present invention.  
       FIGS. 11A  to  10 C are illustrative of a method of manufacturing a wiring board according to the fifth embodiment of the present invention.  
       FIGS. 12A and 12B  are illustrative of a method of manufacturing a wiring board according to a sixth embodiment of the present invention.  
       FIG. 13  shows a semiconductor device according to an embodiment to which the present invention is applied.  
       FIG. 14  shows an electronic instrument including a semiconductor device according to an embodiment to which the present invention is applied.  
       FIG. 15  shows another electronic instrument including a semiconductor device according to an embodiment to which the present invention is applied. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT  
      Embodiments of the present invention may easily manufacture a highly reliable wiring board.  
      (1) A method of manufacturing a wiring board according to one embodiment of the present invention includes:  
      softening a receiving layer formed of a thermoplastic resin by applying heat;  
      forming an interconnect layer on the receiving layer which is softened by the application of heat using a solvent containing conductive particles; and  
      causing the conductive particles to be bonded together by heating the interconnect layer.  
      According to this method of manufacturing a wiring board, since the receiving layer is in a softened state when providing the solvent containing the conductive particles, occurrence of blurring or bulging can be prevented. Moreover, the hardened receiving layer has high adhesion to the interconnect layer including the bonded conductive particles. Therefore, a highly reliable wiring board can be easily manufactured.  
      (2) With this method of manufacturing a wiring board, the interconnect layer may be formed by ejecting the solvent containing the conductive particles.  
      (3) With this method of manufacturing a wiring board, the receiving layer may be formed on a base material.  
      (4) This method of manufacturing a wiring board may further include:  
      removing the base material from the receiving layer after causing the conductive particles to be bonded together.  
      (5) A wiring board according to another embodiment of the present invention is manufactured by the above method.  
      (6) A semiconductor device according to a further embodiment of the present invention includes:  
      the above wiring board; and  
      a semiconductor chip electrically connected with the wiring board.  
      (7) An electronic instrument according to a still further embodiment of the present invention includes the above semiconductor device.  
      (8) A method of manufacturing a wiring board according to a still further embodiment of the present invention includes:  
      forming a first interconnect layer on a first receiving layer formed of a thermoplastic resin which has been in a softened state by using a solvent containing conductive particles;  
      forming a second receiving layer in a softened state on the first receiving layer and the first interconnect layer by using a thermoplastic resin;  
      forming a second interconnect layer on the second receiving layer which has been in the softened state by using a solvent containing conductive particles; and  
      causing the thermoplastic resins of the first and second receiving layers to be softened and the conductive particles to be bonded together in a connecting portion of the first and second interconnect layers by applying heat.  
      According to this method of manufacturing a wiring board, since the first and second receiving layers are in a softened state when providing the solvent containing the conductive particles, occurrence of blurring or bulging can be prevented. Moreover, since the first and second receiving layers adhere to each other when the first and second receiving layers are in a softened state, interlayer separation does not occur or rarely occurs. Furthermore, the hardened first or second receiving layer has high adhesion to the first or second interconnect layer including the bonded conductive particles. Therefore, a highly reliable wiring board can be easily manufactured.  
      (9) With this method, the conductive particles included in the first interconnect layer may be dispersed in the solvent in a state in which each of the conductive particles is covered with a coating material for preventing a reaction between the conductive particles, and the method may further include decomposing the coating material by heating the first interconnect layer before forming the second receiving layer.  
      (10) With this method of manufacturing a wiring board, the first and second interconnect layers may be formed by ejecting the solvent containing the conductive particles.  
      (11) With this method of manufacturing a wiring board, the first receiving layer may be formed on a base material.  
      (12) This method of manufacturing a wiring board may further include:  
      removing the base material from the first receiving layer after causing the conductive particles to be bonded together in the connecting portion of the first and second interconnect layers.  
      (13) A wiring board according to a still further embodiment of the present invention is manufactured by any one of the above methods ( 8 ) to ( 12 ).  
      (14) A semiconductor device according to a still further embodiment of the present invention includes:  
      the above wiring board mentioned in ( 13 ); and  
      a semiconductor chip electrically connected with the wiring board.  
      (15) An electronic instrument according to a yet further embodiment of the present invention includes the above semiconductor device mentioned in (14).  
      The embodiments of the present invention are described below with reference to the drawings.  
     First Embodiment  
       FIGS. 1A  to  3 B are illustrative of a method of manufacturing a wiring board according to a first embodiment of the present invention. In the present embodiment, a receiving layer  10  formed by using a thermoplastic resin (organic material such as a polyamide or a thermoplastic polyimide, for example) is used, as shown in  FIG. 1A . The receiving layer  10  may be formed on a base material  12  (substrate, for example). The base material  12  may be formed of a metal such as copper, a thermosetting resin (polyimide or epoxy resin, for example), or glass. The receiving layer  10  may be formed to have a flat surface. The receiving layer  10  has insulating properties and may be called a (first) insulating layer.  
      As shown in  FIG. 1B , the receiving layer  10  is softened by applying heat. The receiving layer  10  may have viscosity in this state. An interconnect layer  14  (hereinafter may be called “first interconnect layer”) is formed on the receiving layer  10  in a softened state. The interconnect layer  14  is formed by using a solvent containing conductive particles (metallic ink, for example). The conductive particles may be formed of a material which is rarely oxidized and has a low electrical resistance, such as gold or silver. As a solvent containing fine gold particles, “Perfect Gold” (manufactured by Vacuum Metallurgical Co., Ltd.) may be used. As a solvent containing fine silver particles, “Perfect Silver” (manufactured by Vacuum Metallurgical Co., Ltd.) may be used. There are no specific limitations to the size of the particles. The particles used herein are particles which can be ejected together with a solvent. The interconnect layer  14  may be formed by ejecting a solvent containing conductive particles using an ink-jet method or a Bubble Jet (registered trademark) method, or may be formed by mask printing or screen printing. The conductive particles may be covered with a coating material in order to prevent a reaction between the particles. The solvent may be dried to only a small extent and have resolubility. The conductive particles may be uniformly dispersed in a solvent.  
      According to the present embodiment, since the solvent containing conductive particles is provided on the thermoplastic resin in a softened state, occurrence of blurring or bulging can be prevented when forming the interconnect layer  14 . The conductive particles (or conductive particles and coating material) may be allowed to remain by drying the interconnect layer  14  to volatilize the solvent. The interconnect layer  14  may be dried at a temperature from room temperature or more to 100° C. or less. The coating material which covers the conductive particles may be decomposed by heating the interconnect layer  14 .  
      As shown in  FIG. 1C , heat is applied to the interconnect layer  14 . The interconnect layer  14  may be heated at a temperature at which the conductive particles in the interconnect layer  14  are bonded together (sintered, for example) (about 300-600° C., for example). The heat may be applied for about one hour. This causes the conductive particles to form a conductive film or a conductive layer. The thermoplastic resin may be further softened.  
      As shown in  FIG. 1D , the receiving layer  10  is cooled to harden. The temperature of the receiving layer  10  may be decreased at ordinary temperature (or room temperature) instead of positively cooling the receiving layer  10 . After the thermoplastic resin which makes up the receiving layer  10  is hardened and the conductive particles are bonded together, adhesion between the receiving layer  10  and the interconnect layer  14  is increased, whereby a highly reliable wiring board can be obtained.  
      As shown in  FIG. 2A , an insulating layer  20  (hereinafter may be called “second insulating layer”) may be formed on the receiving layer  10  so as to cover the interconnect layer  14 . The description of the receiving layer  10  may be applied to the material for the insulating layer  20 . In the case of forming the insulating layer  20 , the solvent is volatilized from at least the interconnect layer  14  before forming the insulating layer  20 . In the present embodiment, the isulating layer  20  is formed after causing the conductive particles in the interconnect layer  14  to be bonded together (sintered, for example). In the case of forming the insulating layer  20  by using a thermoplastic resin, the thermoplastic resin is softened by applying heat. In this case, the receiving layer  10  may be softened by the applied heat. A contact hole  24  is formed in the insulating layer  20 .  
      As shown in  FIG. 2B , a second interconnect layer  26  is formed on the insulating layer  20 . The description of the first interconnect layer  14  may be applied to the material and the formation method for the second interconnect layer  26 . Since the insulating layer  20  has the same function as the receiving layer  10  for the second interconnect layer  26 , the insulating layer  20  may be called a receiving layer. The second interconnect layer  26  is formed to come in contact with the first interconnect layer  14  through the contact hole  24 . In the case of forming the second interconnect layer  26  by using a solvent containing conductive particles, the solvent may be ejected into the contact hole  24 .  
      As shown in  FIG. 2C , the conductive particles in the second interconnect layer  26  may be bonded together by applying heat. The insulating layer  20  and the second interconnect layer  26  may have the features described for the receiving layer  10  and the first interconnect layer  14 , and achieve the same effects.  
      As shown in  FIG. 3A , a third insulating layer  30  may be formed on the insulating layer  20  (second insulating layer) so as to cover the second interconnect layer  26 . The description of the insulating layer  20  may be applied to the material for the third insulating layer  30 . A contact hole  34  may be formed in the third insulating layer  30 . A contact post  36  may be formed on the second interconnect layer  26  through the contact hole  34 .  
      As shown in  FIG. 3B , a terminal section  38  may be formed on the contact post  36 . The terminal section  38  may be formed to be larger than the upper surface of the contact post  36 . In this case, the peripheral section of the terminal section  38  may be placed on the third insulating layer  30 . The terminal section  38  may be formed by electroless plating of Ni, Cu, or the like.  
      The base material  12  may be removed from the receiving layer  10 . For example, a copper plate may be used as the base material  12 , and the base material  12  may be dissolved by immersing the base material  12  in an etchant such as ferric chloride. This step is performed after causing the conductive particles (first and second interconnect layers  14  and  26 ) to be bonded together. This enables a thin stacked wiring board to be obtained.  
      According to the present embodiment, the hardened receiving layer  10  has high adhesion to the interconnect layer  14  including the bonded conductive particles. Therefore, a highly reliable wiring board can be easily manufactured.  
     Second Embodiment  
       FIGS. 4A  to  4 D are illustrative of a method of manufacturing a wiring board according to a second embodiment of the present invention. In the present embodiment, an interconnect layer  40  is formed on the receiving layer  10 , as shown in  FIG. 4A . The base material  12  may be used. The interconnect layer  40  is formed to include a contact post  42 . The description of the first embodiment may be applied to the material and the formation method for the receiving layer  10  and the interconnect layer  40 . Specifically, the interconnect layer  40  is formed on the receiving layer  10  in a softened state, and the conductive particles are bonded together by heating the interconnect layer  40 .  
      As shown in  FIG. 4B , an insulating layer  44  is formed on the receiving layer  10  so as to cover the interconnect layer  40 . The insulating layer  44  may cover the contact post  42 . The description of the insulating layer  20  in the first embodiment may be applied to the material and the formation method for the insulating layer  44 . The insulating layer  44  may be formed after causing the conductive particles in the interconnect layer  40  to be bonded together. The insulating layer  44  is removed in the area located on the contact post  42 . This removal step may be performed in a state in which the thermoplastic resin which makes up the insulating layer  44  is softened, or may be performed after the thermoplastic resin is hardened. This removal step may be performed by dissolving the surface of the insulating layer  44 . The upper surface of the contact post  42  is thus exposed, as shown in  FIG. 4C .  
      As shown in  FIG. 4D , a second interconnect layer  46  is formed on the insulating layer  44 . The description of the second interconnect layer  26  in the first embodiment may be applied to the material and the formation method for the second interconnect layer  46 . Since the insulating layer  44  has the same function as the receiving layer  10  for the second interconnect layer  46 , the insulating layer  44  may be called a receiving layer. The second interconnect layer  26  is formed to pass over the contact post  42 . The conductive particles in the second interconnect layer  46  are then bonded together, whereby a stacked wiring board can be manufactured. The description of the first embodiment may be applied to the present embodiment. In the present embodiment, the effects described in the first embodiment can also be achieved.  
     Third Embodiment  
       FIGS. 5A  to  5 C are illustrative of a method of manufacturing a wiring board according to a third embodiment of the present invention. In the present embodiment, the interconnect layer  40  is formed on the receiving layer  10 , and the insulating layer  44  is formed on the interconnect layer  40  in the same manner as described in the second embodiment. The insulating layer  44  is formed to cover the contact post  42 . The other details are the same as the details described with reference  FIGS. 4A and 4B .  
      As shown in  FIG. 5A , a second interconnect layer  50  is formed on the insulating layer  44  in a state in which the thermoplastic resin which makes up the insulating layer  44  is softened. The description of the second interconnect layer  26  in the first embodiment may be applied to the material and the formation method for the second interconnect layer  50 . Since the insulating layer  44  has the same function as the receiving layer  10  for the second interconnect layer  50 , the insulating layer  44  may be called a receiving layer. A part of the insulating layer  44  is present between the second interconnect layer  50  and the contact post  42  in this state.  
      As shown in  FIG. 5B , the conductive particles in the second interconnect layer  50  are bonded together by applying heat. The insulating layer  44  may be softened (further softened) by the applied heat. A pressure may be applied to the second interconnect layer  50  and the interconnect layer  40  in the directions in which the second interconnect layer  50  and the interconnect layer  40  are each pressed against the other after causing the conductive particles to be bonded together so as to form a conductive film or a conductive layer.  
      This causes the contact post  42  to be electrically connected with the second interconnect layer  50 , as shown in  FIG. 5C . A stacked wiring board can be manufactured in this manner. The description of the first embodiment may be applied to the present embodiment. In the present embodiment, the effects described in the first embodiment can also be achieved.  
     Fourth Embodiment  
       FIGS. 6A  to  9 B are illustrative of a method of manufacturing a wiring board (stacked wiring board) according to a fourth embodiment of the present invention. In the present embodiment, a receiving layer  110  formed by using a thermoplastic resin (organic material such as a polyamide or a thermoplastic polyimide, for example) is used, as shown in  FIG. 6A . The first receiving layer  110  may be formed on a base material  112  (substrate, for example). The base material  112  may be formed of a metal such as copper, a thermosetting resin (polyimide or epoxy resin, for example), or glass. The first receiving layer  110  may be formed to have a flat surface. The first receiving layer  110  has insulating properties and may be called a first insulating layer.  
      As shown in  FIG. 6B , the first receiving layer  110  is softened by applying heat. The first receiving layer  110  may be formed by using a thermoplastic resin in a softened state. The receiving layer  110  may have viscosity in a softened state. A first interconnect layer  114  is formed on the first receiving layer  110  in a softened state. The first interconnect layer  114  is formed by using a solvent containing conductive particles (metallic ink, for example). The conductive particles may be formed of a material which is rarely oxidized and has a low electrical resistance, such as gold or silver. As a solvent containing fine gold particles, “Perfect Gold” (manufactured by Vacuum Metallurgical Co., Ltd.) may be used. As a solvent containing fine silver particles, “Perfect Silver” (manufactured by Vacuum Metallurgical Co., Ltd.) may be used. There are no specific limitations to the size of the particles. The particles used herein are particles which can be ejected together with a solvent. The first interconnect layer  114  may be formed by ejecting a solvent containing conductive particles using an ink-jet method or a Bubble Jet (registered trademark) method, or may be formed by mask printing or screen printing. The conductive particles may be covered with a coating material in order to prevent a reaction between the particles. The solvent may be dried to only a small extent and have resolubility. The conductive particles may be uniformly dispersed in a solvent.  
      According to the present embodiment, since the solvent containing conductive particles is provided on the thermoplastic resin in a softened state, occurrence of blurring or bulging can be prevented when forming the interconnect layer  114 . The conductive particles (or conductive particles and coating material) may be allowed to remain by drying the first interconnect layer  114  to volatilize the solvent. The first interconnect layer  114  may be dried at a temperature from room temperature or more to  1   00 C or less.  
      As shown in  FIG. 6C , heat may be applied to the first interconnect layer  114 . The coating material which covers the conductive particles may be decomposed by the applied heat. A gas may be generated when decomposing the coating material. The thermoplastic resin may be further softened.  
      As shown in  FIG. 6D , a second receiving layer  120  is formed on the first interconnect layer  114  and the first receiving layer  110 . The second receiving layer  120  is formed by using a thermoplastic resin. The description of the first receiving layer  110  may be applied to the material and the formation method for the second receiving layer  120 . The second receiving layer  120  has insulating properties and may be called a second insulating layer. The solvent is volatilized from at least the first interconnect layer  114  before forming the second receiving layer  120 . A contact hole  124  is formed in the second receiving layer  120 .  
      The second receiving layer  120  is formed in a softened state. For example, the second receiving layer  120  may be formed in a hardened state and then softened, or the second receiving layer  120  may be formed by using a softened thermoplastic resin.  
      As shown in  FIG. 7A , a second interconnect layer  126  is formed on the second receiving layer  120 . The second interconnect layer  126  is formed by using a solvent containing conductive particles. The description of the first interconnect layer  114  may be applied to the material and the formation method for the second interconnect layer  126 . The second interconnect layer  126  is formed to come in contact with the first interconnect layer  114  through the contact hole  124 . In the case of forming the second interconnect layer  126  by using a solvent containing conductive particles, the solvent may be ejected into the contact hole  124 .  
      As shown in  FIG. 7B , heat may be applied to the second interconnect layer  126 . The coating material which covers the conductive particles may be decomposed by the applied heat. A gas may be generated when decomposing the coating material. The thermoplastic resins which make up the first and second receiving layers  110  and  120  may be further softened.  
      As shown in  FIG. 7C , a third receiving layer  130  may be formed on the second interconnect layer  126  and the second receiving layer  120 . The third receiving layer  130  is formed by using a thermoplastic resin. The description of the first receiving layer  110  may be applied to the material and the formation method for the third receiving layer  130 . The third receiving layer  130  has insulating properties and may be called a third insulating layer. A contact hole  132  may be formed in the third insulating layer  130 . As shown in  FIG. 8A , a contact post  134  may be formed in the contact hole  132 . The material and the formation method for the first interconnect layer  114  may be applied to the material and the formation method for the contact post  134 .  
      Heat is applied to the first and second receiving layers  110  and  120  (and the third receiving layer  130 ). The first and second receiving layers  110  and  120  (and the third receiving layer  130 ) are softened by the applied heat to adhere. As shown in  FIG. 8B , the first and second receiving layers  110  and  120  (and the third receiving layer  130 ) may be integrally softened to form an integral insulating layer  140 . This prevents occurrence of interlayer separation between the first and second receiving layers  110  and  120  (and the third receiving layer  130 ).  
      The first and second receiving layers  110  and  120  may be heated at a temperature at which the conductive particles are bonded together (sintered, for example) in the connecting portion of the first and second interconnect layers  114  and  126  (about 300-600° C., for example). The heat may be applied for about one hour. The conductive particles form a conductive film or a conductive layer.  
      As shown in  FIG. 8C , after the thermoplastic resins which make up the first and second receiving layers  110  and  120  (and the third receiving layer  130 ) are hardened and the conductive particles are bonded together, the first and second interconnect layers  114  and  126  have high adhesion to the insulating layer  140  (adhesion between the first interconnect layer  114  and the first and second receiving layers  110  and  120 , or adhesion between the second interconnect layer  126  and the second and third receiving layers  120  and  130 , in more detail), whereby a highly reliable wiring board (stacked wiring board) is obtained. The conductive particles in the contact post  134  may be bonded together (sintered, for example) in the same manner as described above.  
      As shown in  FIG. 9A , a terminal section  138  may be formed on the contact post  134 . The terminal section  138  may be formed to be larger than the upper surface of the contact post  134 . In this case, the peripheral section of the terminal section  138  may be placed on the insulating layer  140  (or the third receiving layer  130 ). The terminal section  138  may be formed by electroless plating of Ni, Cu, or the like.  
      As shown in  FIG. 9B , the base material  112  may be removed from the first receiving layer  110 . For example, a copper plate may be used as the base material  112 , and the base material  112  may be dissolved by immersing the base material  112  in an etchant such as ferric chloride. This step is performed after causing the thermoplastic resins (first, second, and third receiving layers  110 ,  120 , and  130 ) to be hardened and the conductive particles (connecting portion of the first and second interconnect layers  114  and  126 ) to be bonded together.  
      According to the present embodiment, the first and second interconnect layers  114  and  126  have high adhesion to the insulating layer  140 . Therefore, a highly reliable wiring board (stacked wiring board) can be easily manufactured.  
     Fifth Embodiment  
       FIGS. 10A  to  11 C are illustrative of a method of manufacturing a wiring board (stacked wiring board) according to a fifth embodiment of the present invention. In the present embodiment, a first interconnect layer  150  is formed on the first receiving layer  110 , as shown in  FIG. 10A . The base material  112  may be used. The first interconnect layer  150  is formed to include a contact post  152 . The description of the first interconnect layer  114  may be applied to the material and the formation method for the first interconnect layer  150 .  
      As shown in  FIG. 10B , the coating material which covers the conductive particles in the first interconnect layer  150  may be decomposed by applying heat. A gas may be generated when decomposing the coating material. The thermoplastic resin which makes up the first receiving layer  110  may be further softened.  
      As shown in  FIG. 10C , a second receiving layer  154  is formed on the first interconnect layer  150  and the first receiving layer  110 . The second receiving layer  154  may cover the contact post  152 . The description of the second receiving layer  120  in the fourth embodiment may be applied to the material and the formation method for the second receiving layer  154 .  
      As shown in  FIG. 11A , at least the upper surface of the contact post  152  is exposed from the second receiving layer  154 . The surface of the second receiving layer  154  may be removed so that the second receiving layer  154  becomes thinner. The surface of the second receiving layer  154  may be dissolved.  
      As shown in  FIG. 11B , a second interconnect layer  156  is formed on the second receiving layer  154 . The description of the second interconnect layer  126  in the fourth embodiment may be applied to the material and the formation method for the second interconnect layer  156 . The second interconnect layer  156  is formed to pass over the contact post  152 .  
      As shown in  FIG. 11C , the thermoplastic resins of the first and second receiving layers  110  and  154  are softened by applying heat. An integral insulating layer  158  may be formed by this step. The conductive particles are bonded together in the connecting portion of the first and second interconnect layers  150  and  156  by applying heat. A wiring board (stacked wiring board) is manufactured in this manner. The description of the fourth embodiment may be applied to the present embodiment. In the present embodiment, the effects described in the fourth embodiment can also be achieved.  
     Sixth Embodiment  
       FIGS. 12A and 12B  are illustrative of a method of manufacturing a wiring board (stacked wiring board) according to a sixth embodiment of the present invention. In the present embodiment, the first interconnect layer  150  is formed on the first receiving layer  110 , and the second receiving layer  154  is formed on the first interconnect layer  150  in the same manner as described in the fifth embodiment. The second receiving layer  154  is formed to cover the contact post  152 . The other details are the same as the details described with reference  FIG. 10C .  
      As shown in  FIG. 12A , a second interconnect layer  160  is formed on the second receiving layer  154  in a state in which the thermoplastic resin which makes up the second receiving layer  154  is softened. The description of the second interconnect layer  126  in the fourth embodiment may be applied to the material and the formation method for the second interconnect layer  160 . A part of the second receiving layer  154  is present between the second interconnect layer  160  and the contact post  152  in this state.  
      The conductive particles are bonded together in the connecting portion of the first and second interconnect layers  150  and  160  by applying heat. The first and second receiving layers  110  and  154  may be softened (further softened) by the applied heat. The first and second receiving layers  110  and  154  may form an integral insulating layer  162 . A pressure may be applied to the second interconnect layer  150  and the interconnect layer  160  in the directions in which the second interconnect layer  150  and the interconnect layer  160  are each pressed against the other after causing the conductive particles to be bonded together so as to form a conductive film or a conductive layer.  
      This causes the contact post  152  to be electrically connected with the second interconnect layer  160 , as shown in  FIG. 12B . A wiring board (stacked wiring board) is manufactured in this manner. The description of the fourth embodiment may be applied to the present embodiment. In the present embodiment, the effects described in the fourth embodiment can also be achieved.  
       FIG. 13  shows a semiconductor device which includes a wiring board  1000  (or stacked wiring board) described in one of the above embodiments, and a semiconductor chip  1  electrically connected with the wiring board  1000 .  FIGS. 14 and 15  respectively show a notebook-type personal computer  2000  and a portable telephone  3000  as examples of electronic instruments including the semiconductor device.  
      The present invention is not limited to the above-described embodiments. Various modifications and variations are possible. For example, the present invention includes configurations essentially the same as the configurations described in the embodiments (for example, configurations having the same function, method, and results, or configurations having the same object and results). The present invention includes configurations in which any unessential part of the configuration described in the embodiments is replaced. The present invention includes configurations having the same effects or achieving the same object as the configurations described in the embodiments. The present invention includes configurations in which conventional technology is added to the configurations described in the embodiments.