Circuit forming method and circuit forming apparatus

Abstract

A circuit forming method according to the present disclosure comprises: a first component placement step for placing, on a wiring, a first component having conduction parts, which are conductive to each other between an upper surface and a lower surface, such that the conduction part on the lower surface of the first component and the wiring are electrically connected; a resin layer formation step for forming, on the first component and the wiring, a resin layer having an opening through which the conduction part on the upper surface of the first component is exposed; and a second component placement step for placing, on the first component, a second component having a conduction part on at least a lower surface such that the conduction part on the lower surface of the second component and the conduction part on the upper surface of the first component exposed through the opening are electrically connected.

Description

Circuit forming method and circuit forming device

[0001] The present invention relates to a circuit forming method and a circuit forming apparatus for a circuit board on which a plurality of components are stacked.

[0002] Japanese Patent Application Laid-Open No. 2003-144992 discloses a technique for forming a circuit board on which a plurality of components are stacked.

[0003] JP 2007-329452 Public Relations

[0004] The present invention aims to appropriately form a circuit board on which a plurality of components are stacked.

[0005] In order to solve the above-mentioned problems, this specification discloses a circuit formation method including: a first component placement step of placing a first component having a conductive portion that provides electrical continuity between its upper and lower surfaces on wiring such that the conductive portion on the lower surface of the first component is electrically connected to the wiring; a resin layer formation step of forming a resin layer on the first component and the wiring, the resin layer having an opening through which the conductive portion on the upper surface of the first component is exposed; and a second component placement step of placing a second component having a conductive portion on at least its lower surface on the first component such that the conductive portion on the lower surface of the second component is electrically connected to the conductive portion on the upper surface of the first component that is exposed through the opening.

[0006] This specification also discloses a circuit forming apparatus that includes a mounting device that mounts a component at an arbitrary position, a resin layer forming device that forms a resin layer using a curable resin, and a control device, wherein the control device performs the following steps: a first component mounting process in which the mounting device mounts a first component having a conductive portion that provides electrical conductivity between its upper and lower surfaces on wiring so that the conductive portion on the underside of the first component is electrically connected to the wiring; a resin layer forming process in which the resin layer forming device forms a resin layer on the first component and the wiring, the resin layer having an opening that exposes the conductive portion on the upper surface of the first component; and a second component mounting process in which the mounting device mounts a second component having a conductive portion on at least its underside on the first component so that the conductive portion on the underside of the second component is electrically connected to the conductive portion on the upper surface of the first component that is exposed through the opening.

[0007] In the present disclosure, a first component having a conductive portion that provides electrical continuity between its upper and lower surfaces is placed on a wiring such that the conductive portion on the lower surface of the first component is electrically connected to the wiring. Next, a resin layer having an opening through which the conductive portion on the upper surface of the first component is exposed is formed on the first component and the wiring. Then, a second component having a conductive portion on at least its lower surface is placed on the first component such that the conductive portion on the lower surface of the second component is electrically connected to the conductive portion on the upper surface of the first component exposed through the opening. This allows for the appropriate formation of a circuit board in which multiple components are stacked.

[0008] 1 is a diagram showing an example of a circuit forming apparatus; 2 is a block diagram showing an example of a control device; 3 is a cross-sectional view showing an example of a circuit board on which a resin laminate has been formed; 4 is a cross-sectional view showing an example of a circuit board on which wiring has been formed on the resin laminate; 5 is a cross-sectional view showing an example of a circuit board on which another resin laminate has been formed on the resin laminate; 6 is a cross-sectional view showing an example of a circuit board on which wiring to be connected to wiring has been formed; 7 is a cross-sectional view showing an example of a circuit board on which a resin laminate has been formed so that ends of the wiring are exposed; 8 is a cross-sectional view showing an example of a circuit board on which a conductive paste has been applied on the wiring; 9 is a cross-sectional view showing an example of a circuit board on which a thermosetting resin has been applied on the resin laminate; 10 is a cross-sectional view showing an example of a circuit board on which a first layer of electronic components has been mounted; 11 is a cross-sectional view showing an example of a circuit board on which an electronic component has been pressed against the resin laminate; 12 is a cross-sectional view showing an example of a circuit board on which a thermosetting resin has been applied around the electronic component; 13 is a cross-sectional view showing an example of a circuit board on which wiring to be connected to wiring has been formed; 14 is a cross-sectional view showing an example of a circuit board on which a resin laminate has been formed so that ends of the wiring are exposed; FIG. 1 is a cross-sectional view showing an example of a circuit board in a state where a second-layer electronic component is mounted; FIG. 2 is a cross-sectional view showing an example of a circuit board in a state where wiring is formed on a resin laminate; FIG. 3 is a cross-sectional view showing an example of a circuit board in a state where a resin laminate is further formed on the resin laminate; FIG. 4 is a cross-sectional view showing an example of a circuit board in a state where a first-layer electronic component is mounted; FIG. 5 is a cross-sectional view showing an example of a circuit board in a state where a resin laminate is formed so as to cover the electronic component; FIG. 6 is a cross-sectional view showing an example of a circuit board in a state where wiring is formed to connect with electrodes on the upper surface of the electronic component; FIG. 7 is a cross-sectional view showing an example of a circuit board in a state where a resin laminate is further formed on the resin laminate; FIG. 8 is a cross-sectional view showing an example of a circuit board in a state where a second-layer electronic component is mounted; FIG. 9 is a cross-sectional view showing an example of a circuit board in a state where wiring is formed on the resin laminate covering the electronic component;1A and 1B are cross-sectional views showing an example of a circuit board in a state where bumps are formed on wiring and inside openings, respectively, and in a state where electronic components on a second layer are mounted.

[0009] 1 shows an example of a circuit forming apparatus 10. The circuit forming apparatus 10 includes a conveying device 20, a first modeling unit 22, a second modeling unit 23, a third modeling unit 24, a fourth modeling unit 25, a pressing unit 26, a mounting unit 27, and a control device (see FIG. 2) 28. The conveying device 20, the first modeling unit 22, the second modeling unit 23, the third modeling unit 24, the fourth modeling unit 25, the pressing unit 26, and the mounting unit 27 are arranged on a base 29 of the circuit forming apparatus 10. The base 29 has a generally rectangular shape, and in the following description, the longitudinal direction of the base 29 will be referred to as the X-axis direction, the lateral direction of the base 29 as the Y-axis direction, and the direction perpendicular to both the X-axis direction and the Y-axis direction as the Z-axis direction.

[0010] The transport device 20 includes an X-axis slide mechanism 30 and a Y-axis slide mechanism 32. The X-axis slide mechanism 30 includes an X-axis slide rail 34 and an X-axis slider 36. The X-axis slide rail 34 is disposed on the base 29 so as to extend in the X-axis direction. The X-axis slider 36 is held by the X-axis slide rail 34 so as to be slidable in the X-axis direction. The X-axis slide mechanism 30 also includes an electromagnetic motor (see FIG. 2) 38, which is driven to move the X-axis slider 36 to any position in the X-axis direction. The Y-axis slide mechanism 32 also includes a Y-axis slide rail 50 and a stage 52. The Y-axis slide rail 50 is disposed on the base 29 so as to extend in the Y-axis direction and is movable in the X-axis direction. One end of the Y-axis slide rail 50 is connected to the X-axis slider 36. A stage 52 is held on the Y-axis slide rail 50 so as to be slidable in the Y-axis direction. Furthermore, the Y-axis slide mechanism 32 has an electromagnetic motor (see FIG. 2) 56, and the stage 52 moves to any position in the Y-axis direction by driving the electromagnetic motor 56. As a result, the stage 52 moves to any position on the base 29 by driving the X-axis slide mechanism 30 and the Y-axis slide mechanism 32.

[0011] The stage 52 has a base 60, a holding device 62, an elevating device (see FIG. 2) 64, and a heater (see FIG. 2) 66. The base 60 is formed in a flat plate shape, and a substrate is placed on the upper surface. The holding devices 62 are provided on both sides of the base 60 in the X-axis direction. The holding devices 62 clamp both edges of the substrate placed on the base 60 in the X-axis direction, thereby fixedly holding the substrate. The elevating device 64 is disposed below the base 60 and raises and lowers the base 60. The heater 66 is built into the base 60 and heats the substrate placed on the base 60 to a desired temperature.

[0012] The first modeling unit 22 is a unit that models the wiring of a circuit board and includes a first printing unit 72 and a baking unit 74. The first printing unit 72 includes an inkjet head 76 (see FIG. 2 ) that ejects metal ink in a linear pattern. The metal ink is a dispersion of nanometer-sized metal particles, such as silver particles, in a solvent. The surfaces of the metal particles are coated with a dispersant to prevent aggregation in the solvent. The inkjet head 76 ejects the metal ink from multiple nozzles using, for example, a piezoelectric method using piezoelectric elements.

[0013] The baking unit 74 has an infrared irradiation device 78 (see FIG. 2). The infrared irradiation device 78 is a device that irradiates the ejected metal ink with infrared rays. The metal ink irradiated with infrared rays is baked, forming wiring. Note that baking of metal ink is a phenomenon in which, by applying energy, the solvent is vaporized and the protective film on the metal particles, i.e., the dispersant, is decomposed, and the metal particles come into contact or fuse together, thereby increasing the conductivity. Then, by baking the metal ink, metal wiring is formed.

[0014] The second modeling unit 23 is a unit that models the resin layer of the circuit board, and includes a second printing unit 84 and a curing unit 86. The second printing unit 84 includes an inkjet head 88 (see FIG. 2 ) that ejects ultraviolet curable resin. The ultraviolet curable resin is a resin that hardens when irradiated with ultraviolet light. The inkjet head 88 may be, for example, a piezo-type inkjet head using a piezoelectric element, or a thermal-type inkjet head that heats the resin to generate bubbles and ejects the resin from multiple nozzles.

[0015] The curing unit 86 has a planarizing device (see FIG. 2) 90 and an irradiation device (see FIG. 2) 92. The planarizing device 90 flattens the top surface of the UV-curable resin ejected by the inkjet head 88. For example, the planarizing device 90 makes the thickness of the UV-curable resin uniform by leveling the surface of the UV-curable resin and scraping off excess resin with a roller or blade. The irradiation device 92 is equipped with a mercury lamp or LED as a light source and irradiates the ejected UV-curable resin with ultraviolet light. This hardens the ejected UV-curable resin, forming a resin layer.

[0016] The third modeling unit 24 is a unit that models connection portions between electrodes and wiring of electronic components on a circuit board, and includes a third printing unit 100. The third printing unit 100 includes a dispenser 106 (see FIG. 2 ), which dispenses conductive paste. The conductive paste is a resin that hardens when heated at a relatively low temperature, with micrometer-sized metal particles dispersed in it. The metal particles are flake-shaped, and the viscosity of the conductive paste is relatively high compared to metal ink.

[0017] The conductive paste dispensed by the dispenser 106 is then heated by the heater 66 built into the base 60. The resin in the heated conductive paste hardens. At this time, the resin in the conductive paste hardens and shrinks, causing the flake-shaped metal particles dispersed in the resin to come into contact with each other. This allows the conductive paste to exhibit conductivity. The resin in the conductive paste is an organic adhesive, and exhibits adhesive strength when hardened by heating.

[0018] The fourth modeling unit 25 is a unit that models resin for fixing electronic components to a circuit board, and includes a fourth printing unit 110. The fourth printing unit 110 includes a dispenser 116 (see FIG. 2 ) that dispenses thermosetting resin. Thermosetting resin is a resin that hardens when heated. The dispenser 116 uses, for example, an air pulse method that uses compressed air. The thermosetting resin dispensed by the dispenser 116 is heated by a heater 66 built into the base 60 and hardens.

[0019] The pressing unit 26 is a unit for pressing the circuit board and includes a pressing section 120. The pressing section 120 includes a pressing plate (see FIG. 11) 122, a rubber plate (see FIG. 11) 124, and a cylinder (see FIG. 2) 126. The rubber plate 124 is formed of, for example, silicone rubber and has a plate shape. The pressing plate 122 is formed of, for example, steel and has a plate shape. The rubber plate 124 is attached to the underside of the pressing plate 122, and the pressing plate 122 is pressed against the circuit board by the operation of the cylinder 126. As a result, the circuit board is pressed by the pressing plate 122 via the rubber plate 124. The force pressing the board can be controllably changed by controlling the operation of the cylinder 126.

[0020] The mounting unit 27 is a unit that mounts electronic components on a circuit board and includes a supply unit 130 and a mounting unit 132. The supply unit 130 includes a plurality of tape feeders (see FIG. 2) 134 that feed taped electronic components one by one, and supplies the electronic components at a supply position. Note that the supply unit 130 is not limited to the tape feeders 134, and may also be a tray-type supply device that picks up and supplies electronic components from a tray. The supply unit 130 may also be configured to include both tape-type and tray-type supply devices, or other types of supply devices.

[0021] The mounting unit 132 has a mounting head 136 (see FIG. 2) and a moving device 138 (see FIG. 2). The mounting head 136 has a suction nozzle (not shown) for suctioning and holding electronic components. The suction nozzle sucks and holds electronic components by air when negative pressure is supplied from a positive / negative pressure supply device (not shown). The positive / negative pressure supply device then supplies a slight positive pressure to the suction nozzle, which then releases the electronic component. The moving device 138 also moves the mounting head 136 between the position where electronic components are supplied by the tape feeder 134 and the circuit board placed on the base 60. As a result, in the mounting unit 132, electronic components supplied from the tape feeder 134 are held by the suction nozzle, and the electronic components held by the suction nozzle are mounted onto the circuit board.

[0022] 2 , the control device 28 includes a controller 140 and a plurality of drive circuits 142. The plurality of drive circuits 142 are connected to the electromagnetic motors 38, 56, the holding device 62, the lifting device 64, the heater 66, the inkjet head 76, the infrared irradiation device 78, the inkjet head 88, the flattening device 90, the irradiation device 92, the dispensers 106, 116, the cylinder 126, the tape feeder 134, the mounting head 136, and the moving device 138. The controller 140 includes a CPU, ROM, RAM, etc., and is primarily a computer, and is connected to the plurality of drive circuits 142. As a result, the controller 140 controls the operations of the conveying device 20, the first modeling unit 22, the second modeling unit 23, the third modeling unit 24, the fourth modeling unit 25, the pressing unit 26, and the mounting unit 27.

[0023] In the circuit forming apparatus 10, a resin laminate is formed on the base 60 using the above-described configuration, and wiring is formed on the upper surface of the resin laminate. Subsequently, electrodes of electronic components are electrically connected to the wiring via conductive paste, and the electronic components are fixed with resin. Then, a circuit board is formed by stacking multiple electronic components.

[0024] An example of a process for forming a circuit board will be described. Specifically, first, the stage 52 is moved to below the second modeling unit 23. Then, in the second modeling unit 23, a resin laminate 152 is formed on the base 60 of the stage 52, as shown in FIG. 3 . The resin laminate 152 is formed by repeatedly discharging an ultraviolet curable resin from the inkjet head 88 and irradiating the discharged ultraviolet curable resin with ultraviolet light by the irradiation device 92.

[0025] More specifically, in the second printing unit 84 of the second modeling unit 23, the inkjet head 88 ejects a thin film of ultraviolet curable resin onto the upper surface of the base 60. Then, after the ultraviolet curable resin has been ejected in the form of a thin film, the ultraviolet curable resin is flattened by a flattening device 90 in the curing unit 86 so that the film thickness of the ultraviolet curable resin becomes uniform. Then, the irradiation device 92 irradiates the thin film of ultraviolet curable resin with ultraviolet rays. As a result, a thin film resin layer 153 is formed on the base 60.

[0026] Next, the inkjet head 88 ejects a thin film of ultraviolet curable resin onto the thin film resin layer 153. The thin film of ultraviolet curable resin is then flattened by a flattening device 90, and an irradiation device 92 irradiates the ejected thin film of ultraviolet curable resin with ultraviolet light, thereby laminating thin film resin layers 153 on thin film resin layers 153. In this manner, the ejection of ultraviolet curable resin onto the thin film resin layer 153 and the irradiation with ultraviolet light are repeated, and a plurality of resin layers 153 are laminated, thereby forming a resin laminate 152.

[0027] Next, once the resin laminate 152 is formed, the stage 52 is moved below the first modeling unit 22. Then, in the first printing unit 72 of the first modeling unit 22, the inkjet head 76 ejects metal ink 160 in lines in accordance with the circuit pattern onto the upper surface of the resin laminate 152, as shown in FIG. 4 . Subsequently, in the baking unit 74 of the first modeling unit 22, the infrared irradiation device 78 irradiates infrared rays onto the metal ink 160 ejected in accordance with the circuit pattern. This bakes the metal ink 160, and wiring 162 is formed on the upper surface of the resin laminate 152. Note that in FIG. 4 , two wirings 162 are formed, and when distinguishing between the two wirings 162, one of the two wirings 162 will be referred to as wiring 162a and the other as wiring 162b.

[0028] Next, once the wiring 162 is formed on the resin laminate 152, the stage 52 is moved to below the second modeling unit 23. Then, in the second modeling unit 23, a resin laminate 156 is formed on the resin laminate 152, as shown in FIG. 5 . The resin laminate 156 is formed on the resin laminate 152 so as to be continuous with the end of the wiring 162b facing the wiring 162a and the opposite end. In addition, the portion of the resin laminate 156 that is continuous with the wiring 162b forms an inclined surface 157. Note that, like the resin laminate 152, the resin laminate 156 is formed by repeatedly discharging ultraviolet curable resin using the inkjet head 88, planarizing using the planarizing device 90, and irradiating with ultraviolet light using the irradiation device 92.

[0029] Next, the stage 52 is moved below the first modeling unit 22, and in the first modeling unit 22, the wiring 166 is formed on the inclined surface 157 of the resin laminate 156 so as to be in contact with the wiring 162b, as shown in Fig. 6. Note that, like the wiring 162, the wiring 166 is formed by ejecting metal ink from the inkjet head 76 and irradiating infrared rays from the infrared irradiation device 78.

[0030] Next, the stage 52 is moved to below the second modeling unit 23. Then, in the second modeling unit 23, a resin laminate 168 is formed on the resin laminate 152, as shown in FIG. 7 . The resin laminate 168 is formed on the resin laminate 152 so that the opposing ends of the two wirings 162 are exposed and so that the resin laminate 168 is continuous with the inclined surface 157 of the resin laminate 156. Incidentally, the step portion between the resin laminate 152 and the resin laminate 168 functions as a cavity 170. The resin laminate 168 is formed by the same method as the resin laminate 152.

[0031] Next, the stage 52 is moved below the third modeling unit 24. Then, in the third printing unit 100 of the third modeling unit 24, the dispenser 106 dispenses conductive paste 172 onto the opposing ends of the two wirings 162, as shown in FIG. 8 . When the conductive paste 172 is dispensed onto the ends of the wirings 162 in this manner, the heater 66 built into the base 60 heats the resin laminate 152. At this time, the conductive paste 172 is heated through the resin laminate 152 and hardens. As a result, the conductive paste 172 exhibits conductivity. Note that the hardened conductive paste 172 functions as a bump, and therefore the hardened conductive paste 172 is referred to as a bump 174.

[0032] Next, the stage 52 is moved to below the fourth modeling unit 25. Then, in the fourth printing unit 110 of the fourth modeling unit 25, the dispenser 116 dispenses the thermosetting resin 176 onto the upper surface of the resin laminate 152 between the opposing ends of the two wirings 162, as shown in FIG.

[0033] Next, the stage 52 is moved below the mounting unit 27. In the mounting unit 27, an electronic component 178 (see FIG. 10 ) is supplied by the tape feeder 134, and the electronic component 178 is held by the suction nozzle of the mounting head 136. The electronic component 178 is composed of a component body 180 and two electrodes 182 disposed at both ends of the component body 180. The electronic component 178 is a so-called chip component, and the electrodes 182 are electrically connected between the top and bottom surfaces of the electronic component 178. The mounting head 136 is then moved by the moving device 138, and the electronic component 178 held by the suction nozzle is mounted inside the cavity 170 so that it is electrically connected to the wiring 162, as shown in FIG. 10 . Specifically, the electronic component 178 is mounted so that the electrodes 182 on the bottom surface of the electronic component 178 contact the bumps 174 formed on the wiring 162. At this time, the component body 180 of the electronic component 178 comes into contact with the thermosetting resin 176 dispensed between the wiring 162. That is, the conductive paste 172 is dispensed at the intended mounting position of the electrodes 182 on the wiring 162, and the thermosetting resin 176 is dispensed at the intended mounting position of the component body 180. Therefore, when the electronic component 178 is mounted, the electrodes 182 come into contact with the bumps 174 formed on the wiring 162, and the component body 180 comes into contact with the thermosetting resin 176. The thermosetting resin 176 in contact with the component body 180 is then sealed between the component body 180 and the resin laminate 152. That is, the thermosetting resin 176 is sealed between the upper surface of the resin laminate 152 and the lower surface of the component body 180. Of the two electrodes 182, the electrode that contacts the bump 174 formed on the wiring 162a is referred to as electrode 182a, and the electrode that contacts the bump 174 formed on the wiring 162b is referred to as electrode 182b.

[0034] Once the electronic component 178 is mounted in this manner, the stage 52 is moved below the pressing unit 26. Then, in the pressing portion 120 of the pressing unit 26, as shown in FIG. 11 , the electronic component 178 is pressed from above downward by the pressing plate 122 via the rubber plate 124. Furthermore, while the electronic component 178 is being pressed by the pressing unit 26, the resin laminate 152 is heated by the heater 66 built into the base 60. As a result, the thermosetting resin 176 is heated via the resin laminate 152 and hardens. As the electronic component 178 is pressed by the pressing plate 122 in this manner, the component body 180 and the thermosetting resin 176 come into close contact with each other, and the electrodes 182 and the bumps 174 also come into close contact with each other. As a result, the adhesive force of the thermosetting resin 176 fixes the electronic component 178 to the upper surface of the resin laminate 152 in the component body 180, and the adhesive force between the electrode 182 and the bump 174 ensures electrical connection between the electronic component 178 and the wiring 162.

[0035] Then, when the pressing unit 26 completes pressing, the stage 52 is moved below the fourth modeling unit 25. Then, in the fourth printing unit 110 of the fourth modeling unit 25, the dispenser 116 dispenses the thermosetting resin 186 between the side surface of the electronic component 178 and the cavity 170, as shown in FIG. 12 . Then, the heater 66 built into the base 60 heats the resin laminate 152. As a result, the thermosetting resin 186 is heated through the resin laminate 152 and hardens. At this time, the thermosetting resin 186 hardens while covering the side surfaces of the electronic component 178. In other words, in the electronic component 178 mounted inside the cavity 170, the thermosetting resins 176, 186 are sealed between the upper surface of the resin laminate 152 and the lower surface of the component main body 180, and harden while covering the side surfaces of the electronic component 178. As a result, the electronic component 178 mounted inside the cavity 170 is fixed by the hardened resin.

[0036] Subsequently, the stage 52 is moved to below the first modeling unit 22, and in the first modeling unit 22, a wiring 188 is formed on the resin laminates 156, 168 so as to be in contact with the wiring 166, as shown in Fig. 13. The wiring 188 is formed by the same method as the wiring 162.

[0037] Next, the stage 52 is moved to below the second modeling unit 23. Then, in the second modeling unit 23, a resin laminate 190 is formed on the resin laminate 168 and the electronic component 178, as shown in FIG. 14 . The resin laminate 190 is formed on the resin laminate 168 and the electronic component 178 so as to be continuous with the ends of the wiring 188. In addition, the portion of the resin laminate 190 that is continuous with the wiring 188 is formed as an inclined surface 192. The resin laminate 190 is formed by the same method as the resin laminate 152.

[0038] Next, the stage 52 is moved below the first modeling unit 22, and in the first modeling unit 22, two wirings 196 are formed on the resin laminate 190 as shown in FIG. 15 . When distinguishing between the two wirings 196, one of the two wirings 196 will be referred to as wiring 196a, and the other will be referred to as wiring 196b. Wiring 196b is formed to extend through the inclined surface 192 of the resin laminate 190 to the upper surface of the resin laminate 190 so as to contact wiring 188. On the other hand, wiring 196a is formed so that one end of wiring 196b faces one end of wiring 196b on the upper surface of the resin laminate 190. Wiring 196 is formed by the same method as wiring 162.

[0039] Next, the stage 52 is moved to below the second modeling unit 23. Then, in the second modeling unit 23, a resin laminate 198 is formed on the resin laminates 156, 190, as shown in FIG. 16 . The resin laminate 198 is formed on the resin laminates 156, 190 so that the opposing ends of the two wirings 196 are exposed. Incidentally, the step between the resin laminate 198 and the resin laminate 190 functions as a cavity 199. The resin laminate 198 is formed by the same method as the resin laminate 152.

[0040] 17 , electronic component 200 is mounted in cavity 199 of resin laminate 198 in the same manner as electronic component 178, and is fixed therein by thermosetting resins 202 and 204. That is, once resin laminate 198 is formed, conductive paste is dispensed onto the opposing ends of two wirings 196 and hardened by heating with heater 66, thereby forming bumps 206. Next, thermosetting resin 202 is dispensed between the opposing ends of two wirings 196. Like electronic component 178, electronic component 200 is a chip component and has two electrodes 208. Therefore, the electrodes 208 of electronic component 200 are also electrically connected between the top and bottom surfaces of electronic component 200. Electronic component 200 is then mounted in cavity 199 so that the electrodes 208 on the bottom surface of electronic component 200 contact the bumps 206 formed on wirings 196. Next, electronic component 200 mounted inside cavity 199 is pressed downward by pressure plate 122 via rubber plate 124. At this time, thermosetting resin 202 is heated and hardened. Then, thermosetting resin 204 is dispensed between the side surface of electronic component 200 and cavity 199, and then thermosetting resin 204 is heated and hardened. In this manner, electronic component 200 is mounted inside cavity 199 of resin laminate 198 and fixed by thermosetting resins 202 and 204. Of the two electrodes 208 of electronic component 200, the electrode that contacts bump 206 formed on wiring 196a will be referred to as electrode 208a, and the electrode that contacts bump 206 formed on wiring 196b will be referred to as electrode 208b.

[0041] This results in the formation of a circuit board 210 on which two electronic components 178, 200 are stacked. By forming a circuit board 210 on which multiple electronic components 178, 200 are stacked in this manner, a circuit board on which many electronic components are mounted can be formed. However, in the circuit board 210, wiring is extended from the electrode 182 on the underside of the electronic component 178 located in the lower layer to above the electronic component 178 and connected to the electrode on the underside of the electronic component 200 located in the upper layer, resulting in a long wiring path. Specifically, wiring 162b is connected to electrode 182b on the underside of the electronic component 178 via bump 174. Furthermore, wiring 166, 188, and 196b are formed so as to bypass the side of electronic component 178 and extend above electronic component 178, and wiring 166 is connected to wiring 162b. Furthermore, wiring 196b extending above electronic component 178 is connected to electrode 208b on the underside of electronic component 200 via bump 206. Therefore, the wiring path connecting electrode 182b of electronic component 178 and electrode 208b of electronic component 200 is long, consisting of wires 162b, 166, 188, and 196b. Such a long wiring path may result in an increase in the circuit area or a decrease in circuit characteristics due to increased wiring resistance.

[0042] In consideration of this, in the circuit forming apparatus 10, wiring is drawn out from the electrodes on the upper surface of the lower-layer electronic component, and the wiring is connected to the electrodes on the lower surface of the upper-layer electronic component. Specifically, when the resin laminate 152 is formed on the base 60, two wirings 220a, 220b are formed on the upper surface of the resin laminate 152 in the first modeling unit 22, as shown in FIG. 18 . The wiring 220a is formed in the same position as the wiring 162a on the circuit board 210, and the length of the wiring 220a is approximately the same as the length of the wiring 162a. The wiring 220b is formed in the same position as the wiring 162b on the circuit board 210, but the length of the wiring 220b is shorter than the length of the wiring 162b on the circuit board 210. The wiring 220 is formed using the same method as the wiring 162.

[0043] 19 , in the second modeling unit 23, a resin laminate 222 is formed on the resin laminate 152. The resin laminate 222 is formed on the resin laminate 152 so that the entire wiring 220b is exposed and the end of the wiring 220a facing the end of the wiring 220b is also exposed. Incidentally, the step between the resin laminate 152 and the resin laminate 222 functions as a cavity 223. The resin laminate 222 is formed by the same method as the resin laminate 152.

[0044] Next, as shown in FIG. 20 , electronic component 178 is mounted inside cavity 223 of resin laminate 222 and fixed therein by thermosetting resins 230 and 231. That is, once resin laminate 222 is formed, conductive paste is dispensed onto the opposing ends of two wirings 220 and hardened by heating with heater 66, thereby forming bumps 234. Next, thermosetting resin 230 is dispensed between the opposing ends of two wirings 220. Electronic component 178 is then mounted inside cavity 223 so that electrodes 182 on the undersides of electronic component 178 contact bumps 234 formed on wirings 220. Next, electronic component 178 mounted inside cavity 223 is pressed downward by pressure plate 122 via rubber plate 124. At this time, thermosetting resin 230 is heated and hardened. Then, after thermosetting resin 231 is dispensed between the side surface of electronic component 178 and cavity 223, thermosetting resin 231 is heated and cured. In this manner, electronic component 178 is mounted inside cavity 223 of resin laminate 222 and fixed by thermosetting resins 230, 231. Of the two electrodes 182 of electronic component 178, the electrode that contacts bump 234 formed on wiring 220a is referred to as electrode 182a, and the electrode that contacts bump 234 formed on wiring 220b is referred to as electrode 182b.

[0045] 21 , in the second modeling unit 23, a resin laminate 226 is formed on the resin laminate 222 and the electronic component 178. The resin laminate 226 covers the resin laminate 222 and the electronic component 178 except for the electrode 182b on the upper surface of the electronic component 178, and an opening 228 is formed in the resin laminate 226 to expose the electrode 182b on the upper surface of the electronic component 178. Note that, of the wall surfaces defining the opening 228, the wall surface on the side facing from the electrode 182b to the electrode 182a is formed as an inclined surface 227.

[0046] 22 , in the first modeling unit 22, two wirings 232a and 232b are formed on the upper surface of the resin laminate 226. The wiring 232a is formed in the same position as the wiring 196a on the circuit board 210, and the length of the wiring 232a is approximately the same as the length of the wiring 196a. The wiring 232b is formed so as to approach the wiring 232a from the opening 228 of the resin laminate 226 via the inclined surface 227, and the wiring 232b is connected to the electrode 182b on the upper surface of the electronic component 178 exposed from the opening 228 of the resin laminate 226. The wiring 232 is formed by the same method as the wiring 162.

[0047] 23 , in the second modeling unit 23, a resin laminate 236 is formed on the resin laminate 226. The resin laminate 236 is formed on the resin laminate 226 so that the opposing ends of the two wirings 232 are exposed. The step between the resin laminate 226 and the resin laminate 236 functions as a cavity 238. The resin laminate 236 is formed by the same method as the resin laminate 152.

[0048] 24 , electronic component 200 is mounted inside cavity 238 of resin laminate 236 and fixed therein by thermosetting resins 240 and 242. That is, once resin laminate 236 is formed, conductive paste is dispensed onto the opposing ends of two wirings 232 and hardened by heating with heater 66, thereby forming bumps 246. Next, thermosetting resin 240 is dispensed between the opposing ends of two wirings 232. Electronic component 200 is then mounted inside cavity 238 so that electrodes 208 on the undersides of electronic component 200 contact bumps 246 formed on wirings 232. Next, electronic component 200 mounted inside cavity 238 is pressed downward by pressure plate 122 via rubber plate 124. At this time, thermosetting resin 240 is heated and hardened. Then, after thermosetting resin 242 is dispensed between the side surface of electronic component 200 and cavity 238, thermosetting resin 242 is heated and cured. In this manner, electronic component 200 is mounted inside cavity 238 of resin laminate 236 and fixed by thermosetting resins 240, 242. Of the two electrodes 208 of electronic component 200, the electrode that contacts bump 246 formed on wiring 232a will be referred to as electrode 208a, and the electrode that contacts bump 246 formed on wiring 232b of the two electrodes 208 will be referred to as electrode 208b.

[0049] This forms a circuit board 250 in which two electronic components 178, 200 are stacked. In this circuit board 250, wiring 232b is drawn out from electrode 182b on the top surface of electronic component 178 in the lower layer, and wiring 232b is connected to electrode 208b on the bottom surface of electronic component 200 in the upper layer. Therefore, in circuit board 250, the wiring path connecting electrode 182b of electronic component 178 to electrode 208b of electronic component 200 is significantly shorter than the wiring path connecting electrode 182b of electronic component 178 to electrode 208b of electronic component 200 in circuit board 210. This makes it possible to reduce the circuit area and improve circuit characteristics by reducing wiring resistance.

[0050] Furthermore, in the circuit board 250, the electrode 182b on the underside of the electronic component 178 is connected to the wiring 220b via the bump 234, but the wiring 220b is not connected to any other component or wiring. In this way, the wiring 220b is not used as a member for electrical connection, but by arranging the wiring 220b below the electrode 182b, it is possible to keep the electronic component 178 horizontal inside the circuit board 250.

[0051] Furthermore, in the circuit board 250, the electrodes 182b of the electronic component 178 and the electrodes 208b of the electronic component 200 are connected by wiring 232b, but the electrodes 182b of the electronic component 178 and the electrodes 208b of the electronic component 200 may also be connected by bumps. Specifically, as shown in FIG. 25 , in the second modeling unit 23, a resin laminate 260 is formed on the electronic component 178 and the resin laminate 222. The resin laminate 260 has substantially the same shape as the resin laminate 226 in the circuit board 250, and, like the resin laminate 226, an opening 262 is formed in the resin laminate 260 through which the electrodes 182b on the top surface of the electronic component 178 are exposed. Note that the opening 262 in the resin laminate 260 does not have an inclined surface, unlike the opening 228 in the resin laminate 226. The resin laminate 260 is formed by the same method as the resin laminate 152. Subsequently, when the resin laminate 226 is formed, the wiring 232a is formed on the resin laminate 260 in the first modeling unit 22. Note that only the wiring 232a is formed, and the wiring 232b is not formed as in the circuit board 250.

[0052] 26 , in the second modeling unit 23, a resin laminate 270 is formed on the resin laminate 260. The resin laminate 270 is formed on the resin laminate 260 so that the ends of the wiring 232a and the openings 262 of the resin laminate 260 are exposed. Incidentally, the step between the resin laminate 260 and the resin laminate 270 functions as a cavity 272. The resin laminate 270 is formed by the same method as the resin laminate 152.

[0053] 27 , in the third modeling unit 24, conductive paste is dispensed onto the end of the wiring 232a and hardened by heating with the heater 66, thereby forming a bump 276. Furthermore, conductive paste is dispensed into the opening 262 of the resin laminate 260 and hardened by heating with the heater 66, thereby forming a bump 278. The conductive paste is dispensed into the opening 262 of the resin laminate 260 so that the height dimension of the bump 278 is approximately the same as the height dimension of the bump 276.

[0054] 28 , electronic component 200 is mounted inside cavity 272 of resin laminate 270 and fixed therein by thermosetting resins 280 and 282. That is, once bumps 276 and 278 are formed, thermosetting resin 280 is dispensed between the end of wiring 232a and bump 278. Electronic component 200 is then mounted inside cavity 272 so that electrode 208a on the underside of electronic component 200 contacts bump 276 and electrode 208b on the underside of electronic component 200 contacts bump 278. Next, electronic component 200 mounted inside cavity 272 is pressed downward by pressure plate 122 via rubber plate 124. At this time, thermosetting resin 280 is heated and hardened. Then, after thermosetting resin 282 is dispensed between the side surface of electronic component 200 and cavity 272, thermosetting resin 282 is heated and cured. In this manner, electronic component 200 is mounted inside cavity 272 of resin laminate 270 and fixed by thermosetting resins 280, 282.

[0055] This forms a circuit board 290 in which two electronic components 178, 200 are stacked. In this circuit board 290, the electrode 182b on the top surface of the lower electronic component 178 is connected to the electrode 208b on the bottom surface of the upper electronic component 200 by a bump 278. Therefore, in the circuit board 290, the wiring path connecting the electrode 182b of the electronic component 178 to the electrode 208b of the electronic component 200 is significantly shorter than the wiring path connecting the electrode 182b of the electronic component 178 to the electrode 208b of the electronic component 200 in the circuit board 210. Furthermore, in the circuit board 290, the wiring path connecting the electrode 182b of the electronic component 178 to the electrode 208b of the electronic component 200 is significantly shorter than the wiring path connecting the electrode 182b of the electronic component 178 to the electrode 208b of the electronic component 200 in the circuit board 250. This makes it possible to further reduce the circuit area and further improve the circuit characteristics by further reducing the wiring resistance.

[0056] 2 , the controller 140 of the control device 28 has a first component placement unit 300, a resin layer formation unit 302, a second component placement unit 304, a wiring formation unit 306, and a discharge unit 308. The first component placement unit 300 is a functional unit for placing the electronic component 178 on the circuit board 250, 290 so that the electrodes 182 on the underside of the electronic component 178 are electrically connected to the wiring 220. The resin layer formation unit 302 is a functional unit for forming the resin laminates 226, 260 on the circuit board 250, 290, each having openings 228, 262 through which the electrodes 182 on the upper surface of the electronic component 178 are exposed. The second component placement unit 304 is a functional unit for placing the electronic component 200 on the circuit board 250, 290 so that the electrodes 208 on the underside of the electronic component 200 are electrically connected to the electrodes 182 on the upper surface of the electronic component 178 exposed through the openings 228, 262. Wiring forming unit 306 is a functional unit for forming wiring 232 that electrically connects electrode 182 on the upper surface of electronic component 178 and electrode 208 on the lower surface of electronic component 200 on circuit board 250. Discharging unit 308 is a functional unit for discharging conductive paste into opening 262 of resin laminate 260 on circuit board 290.

[0057] In the above embodiment, the circuit forming apparatus 10 is an example of a circuit forming apparatus. The second modeling unit 23 is an example of a resin layer forming apparatus. The mounting unit 27 is an example of a placement device. The control device 28 is an example of a control device. The electronic component 178 is an example of a first component. The electrode 182 is an example of a conductive portion. The electronic component 200 is an example of a second component. The electrode 208 is an example of a conductive portion. The wiring 220 is an example of a wiring. The resin laminates 226, 260 are examples of resin layers. The openings 228, 262 are examples of openings. The wiring 232 is an example of a wiring. Furthermore, the steps and processes performed by the first component placement unit 300 are examples of a first component placement process and a first component placement process. The steps and processes performed by the resin layer formation unit 302 are examples of a resin layer formation process and a resin layer formation process. The process and processing performed by the second component placement unit 304 are examples of a second component placement process and a second component placement process. The process performed by the wiring formation unit 306 is an example of a wiring formation process. The process performed by the discharge unit 308 is an example of a discharge process.

[0058] The present invention is not limited to the above-described embodiment, and various modifications and improvements can be made based on the knowledge of those skilled in the art. For example, while the above-described embodiment employs electronic components 178 and 200 as components for electrical continuity between the upper and lower surfaces, components such as terminal blocks may also be employed. Terminal blocks function as, for example, contacts, pads, heat sinks, etc., on a circuit board, and have metal lumps exposed on the upper and lower surfaces.

[0059] Furthermore, in the above embodiment, the electronic components 178, 200 are arranged in two layers on the circuit boards 250, 290, but a plurality of electronic components may be arranged in three or more layers.

[0060] DESCRIPTION OF SYMBOLS 10: Circuit forming device 23: Second shaping unit (forming device) 27: Mounting unit (mounting device) 28: Control device 178: Electronic component (first component) 182: Electrode (conductive portion) 200: Electronic component 208: Electrode (conductive portion) 220: Wiring 226: Resin laminate (resin layer) 228: Opening 232: Wiring 260: Resin laminate 262: Opening 300: First component placing section (first component placing process) (first component placing treatment) 302: Resin layer forming section (resin layer forming process) (resin layer forming treatment) 304: Second component placing section (second component placing process) (second component placing treatment) 306: Wiring forming section (wiring forming process) 308: Discharging section (discharging process)

Claims

1. A circuit forming method comprising: a first component placing step of placing a first component having a conductive portion providing electrical continuity between its top and bottom surfaces on wiring such that the conductive portion on the bottom surface of the first component is electrically connected to the wiring; a resin layer forming step of forming a resin layer on the first component and the wiring, the resin layer having an opening through which the conductive portion on the top surface of the first component is exposed; and a second component placing step of placing a second component having a conductive portion on at least its bottom surface on the first component such that the conductive portion on the bottom surface of the second component is electrically connected to the conductive portion on the top surface of the first component exposed through the opening.

2. A circuit forming method as described in claim 1, further comprising a wiring forming step of forming, using a metal-containing liquid containing fine metal particles, wiring that is connected to a conductive portion on the upper surface of the first component exposed from the opening after the resin layer has been formed in the resin layer forming step, and wherein the second component placing step places the second component on the first component such that the conductive portion on the lower surface of the second component is electrically connected to the wiring formed in the wiring forming step.

3. A circuit forming method as described in claim 1, further comprising a discharge step of discharging a conductive fluid onto a conductive portion on the upper surface of the first component exposed from the opening after a resin layer is formed in the resin layer forming step, and wherein the second component placing step places the second component on the first component such that the conductive portion on the lower surface of the second component comes into contact with the conductive fluid discharged in the discharge step.

4. A circuit forming method according to any one of claims 1 to 3, wherein the resin layer forming process forms the resin layer by ejecting a curable resin onto the first component and the wiring.

5. A circuit forming device comprising: a mounting device for mounting a component at an arbitrary position; a resin layer forming device for forming a resin layer using a curable resin; and a control device, wherein the control device executes the following steps: a first component mounting process in which a first component having a conductive portion providing electrical conductivity between its upper and lower surfaces is mounted on wiring by the mounting device such that the conductive portion on the underside of the first component is electrically connected to the wiring; a resin layer forming process in which a resin layer having an opening through which the conductive portion on the upper surface of the first component is exposed is formed on the first component and the wiring by the resin layer forming device; and a second component mounting process in which a second component having at least a conductive portion on its lower surface is mounted on the first component by the mounting device such that the conductive portion on the underside of the second component is electrically connected to the conductive portion on the upper surface of the first component exposed through the opening.