Molding method and molding apparatus

Abstract

To provide a molding method and a molding device which can mold metal wiring satisfying desired electric characteristics even if concentration of metal fine particles in metal-containing liquid is lowered due to residue of a solvent.SOLUTION: A molding method includes: a first supply step of supplying a solvent to a tank; a second supply step of discharging the solvent in the tank, and supplying a metal-containing liquid to the tank, after executing the first supply step; and a molding step of molding metal wiring having predetermined thickness by processing according to concentration of metal fine particles in the metal-containing liquid which is diluted by the solvent remaining in the tank and is supplied in the second supply step, when the metal wiring is molded using the metal-containing liquid, after execution of the second supply step.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present disclosure relates to a technique for forming a metal wiring using a metal-containing liquid containing metal fine particles.

Background Art

[0002] In recent years, as described in the following patent documents, a technique for forming a metal wiring by a three-dimensional lamination forming method using a metal-containing liquid containing metal fine particles has been developed. Specifically, for example, the metal-containing liquid is linearly ejected by an inkjet head according to a circuit pattern. Then, the ejected metal-containing liquid is fired by a laser or the like to form a metal wiring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When forming the above metal wiring by the inkjet method, for example, if the time for not forming the metal wiring becomes long, the metal-containing liquid in the nozzles of the inkjet head may dry, and the metal fine particles may adhere to the nozzles. In such a case, the occurrence of adhesion can be suppressed by discharging the metal-containing liquid in the ink tank and the nozzles and supplying a solvent.

[0005] Also, when restarting the formation of the metal wiring, if the solvent is discharged and the metal-containing liquid is supplied into the ink tank, the solvent may remain in the ink tank, and the metal-containing liquid may be diluted by the solvent. In such a case, the concentration of the metal fine particles in the metal-containing liquid may decrease, the thickness of the formed metal wiring may become thin, and it may not satisfy the desired electrical characteristics.

[0006] This disclosure has been made in view of such circumstances, and aims to provide a fabrication method and fabrication apparatus that can fabricate metal wiring that satisfies desired electrical properties even when the concentration of metal fine particles in the metal-containing liquid decreases due to solvent residue. [Means for solving the problem]

[0007] This specification discloses a manufacturing method for manufacturing metal wiring using a discharge device comprising: a first tank and a second tank capable of storing a metal-containing liquid containing metal fine particles; and a head connected to the first tank and the second tank for discharging the metal-containing liquid supplied from at least one of the first tank and the second tank, the manufacturing method comprising: a first supply step of supplying a solvent to the first tank and the second tank; a second supply step of discharging the solvent from the first tank and the second tank after performing the first supply step and supplying the metal-containing liquid to the first tank and the second tank; and a manufacturing step of manufacturing the metal wiring using the metal-containing liquid after performing the second supply step, wherein the metal wiring is manufactured by a process corresponding to the concentration of metal fine particles in the metal-containing liquid supplied in the second supply step, which is diluted by the solvent remaining in at least one of the first tank and the second tank. Furthermore, the contents of this disclosure can be implemented in various forms, not limited to as a molding method. For example, the contents of this disclosure can also be useful when implemented as a molding apparatus. [Effects of the Invention]

[0008] According to this disclosure, when supplying and discharging solvent to the first and second tanks, and then supplying a metal-containing liquid to the first and second tanks to fabricate metal wiring, a process is performed according to the concentration of metal microparticles diluted by the solvent remaining in at least one of the first and second tanks. This makes it possible to fabricate metal wiring of a predetermined thickness. Therefore, even if the concentration of metal microparticles in the metal-containing liquid decreases due to residual solvent, it is possible to fabricate metal wiring that satisfies the desired electrical properties. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the substrate manufacturing apparatus related to this embodiment. [Figure 2] This is a block diagram of a circuit board manufacturing machine. [Figure 3] This is a diagram showing a circuit board manufactured by a circuit board manufacturing machine. [Figure 4] This is a schematic diagram showing the configuration related to the inkjet head in the first printing section. [Figure 5] This is a diagram illustrating the process of changing from metallic ink to solvent-based ink. [Figure 6] This is a diagram illustrating the process of changing from metallic ink to solvent-based ink. [Figure 7] This is a diagram illustrating the process of changing from a solvent-based ink to a metallic ink. [Figure 8] This is a diagram illustrating the process of changing from a solvent-based ink to a metallic ink. [Figure 9] This is a diagram illustrating the process of changing from a solvent-based ink to a metallic ink. [Figure 10] This graph shows the relationship between the time required for the molding process, the silver concentration, and the amount of ink used. [Figure 11] This is a schematic diagram showing the configuration of the first printing section in an alternative example. [Modes for carrying out the invention]

[0010] (Configuration of the circuit board manufacturing apparatus 10) Hereinafter, a substrate manufacturing apparatus, which is an embodiment of the molding apparatus of this disclosure, will be described with reference to the drawings. Figure 1 shows a substrate manufacturing apparatus 10 according to this embodiment. Figure 2 shows a block diagram of the substrate manufacturing apparatus 10. As shown in Figure 1, the substrate manufacturing apparatus 10 includes a transport device 20, a first molding unit 22, a second molding unit 24, a third molding unit 25, a mounting unit 27, and a control device 28 (see Figure 2). The substrate manufacturing apparatus 10 is an apparatus that uses the inkjet method as a three-dimensional additive manufacturing method to additively manufacture, for example, a substrate 140 as shown in Figure 3, and mounts electronic components 157 on the manufactured substrate 140.

[0011] The transport device 20, the first molding unit 22, the second molding unit 24, the third molding unit 25, and the mounting unit 27 are arranged on the base 29 of the substrate manufacturing apparatus 10. The base 29 is generally rectangular in shape. In the following description, as shown in Figure 1, the longitudinal direction of the base 29 will be referred to as the X-axis direction, the short direction of the base 29 as the Y-axis direction, and the direction perpendicular to both the X-axis and Y-axis directions will be referred to as the Z-axis direction.

[0012] 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 mounted on a base 29 and is arranged along 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. Furthermore, the X-axis slide mechanism 30 has an electromagnetic motor 38 (see Figure 2), which drives the X-axis slider 36 to any position in the X-axis direction.

[0013] 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 mounted on the base 29 and is positioned along the Y-axis direction. One end of the Y-axis slide rail 50 (the upper end in Figure 1) is connected to the X-axis slider 36. This allows the Y-axis slide mechanism 32 to move in the X-axis direction together with the X-axis slider 36. The stage 52 is held in a slidable position in the Y-axis direction by the Y-axis slide rail 50. Furthermore, the Y-axis slide mechanism 32 has an electromagnetic motor 56 (see Figure 2), which drives the stage 52 to any position in the Y-axis direction. Thus, the stage 52 can be moved to any position on the base 29 in the X-axis direction and the Y-axis direction by the driving of the X-axis slide mechanism 30 and the Y-axis slide mechanism 32.

[0014] The stage 52 has a base 60, a holding device 62, and a lifting device 64. The base 60 is formed in a flat plate shape, and a substrate is placed on the upper surface. The holding device 62 is provided on both side portions of the base 60 in the X-axis direction. For example, a pallet 141 (see FIG. 3) for shaping the substrate is disposed on the base 60. The pallet 141 is, for example, a thin plate-like member made of metal. On this pallet 141, for example, a release film 143 (see FIG. 3) is attached, and a substrate 140 is manufactured on the release film 143. The release film 143 is, for example, a film-like member whose adhesive force decreases by heat at a predetermined temperature or higher, and is used to separate the substrate 140 from the pallet 141 after manufacturing the substrate 140. The pallet 141 is placed on the base 60 and is fixedly held with respect to the base 60 by being sandwiched by the holding device 62 at both edge portions in the X-axis direction. Further, the lifting device 64 is provided below the base 60 and raises and lowers the base 60 in the Z-axis direction.

[0015] The first shaping unit 22 is a unit that shapes a metal wiring 147 (see FIG. 3) on the base 60 of the stage 52, and has a first printing unit 72 and a firing unit 74. The first printing unit 72 has an inkjet head 76 (see FIG. 2), and the inkjet head 76 discharges metal ink linearly. The metal ink is one in which metal nanoparticles of nanometer size, for example, silver fine particles, are dispersed in an organic solvent. The metal ink is an example of a metal-containing liquid containing the metal fine particles of the present disclosure. The surface of the metal fine particles is coated with, for example, a dispersant, and aggregation in the organic solvent is prevented. Incidentally, the inkjet head 76 discharges metal ink from a plurality of nozzles by, for example, a piezo method using a piezoelectric element.

[0016] The firing unit 74 has an infrared irradiation device 78 (see FIG. 2). The infrared irradiation device 78 is, for example, an infrared heater, which is a device that irradiates and heats the ejected metal ink with infrared rays. The infrared irradiation device 78 can be switched, for example, between a state of being heated to a first temperature and a state of being heated to a second temperature higher than the first temperature based on the control of the control device 28 (see FIG. 2) of the substrate manufacturing apparatus 10. When the metal ink is heated by the infrared irradiation device 78 at the first temperature, for example, the organic solvent is vaporized and drying proceeds. Also, when the metal ink is heated by the infrared irradiation device 78 at the high second temperature, it is fired to form the final metal wiring 147. The firing of the metal ink here means that by applying thermal energy, the vaporization of the organic solvent, the protective film of the metal fine particles, that is, the decomposition of the dispersant, etc. are performed, and the metal fine particles contact or fuse, resulting in an increase in conductivity. The substrate manufacturing apparatus 10 forms the metal wiring 147 by performing, for example, drying at the first temperature on the ejected metal ink and then firing at the second temperature. Note that the method of forming the metal wiring 147 is not limited to the method described above. The control device 28 may perform firing by heating once without performing the drying process.

[0017] Also, the second shaping unit 24 is a unit that shapes the resin layer 145 (see FIG. 3) on the base 60 of the stage 52, and has a second printing unit 84 and a curing unit 86. The second printing unit 84 has an inkjet head 88 (see FIG. 2). The inkjet head 88 ejects an ultraviolet curable resin. The ultraviolet curable resin is, for example, a resin that has insulating properties and cures by irradiation with ultraviolet rays. Note that the method by which the inkjet head 88 ejects the ultraviolet curable resin may be, for example, a piezo method using a piezoelectric element or a thermal method that heats the resin to generate bubbles and ejects them from a plurality of nozzles.

[0018] The curing unit 86 includes a planarizing device 90 (see Figure 2) and an irradiation device 92 (see Figure 2). The planarizing device 90 flattens the upper surface of the ultraviolet-curable resin ejected by the inkjet head 88. For example, it smooths the surface of the ultraviolet-curable resin and scrapes off excess resin with a roller or blade, thereby making the thickness of the ultraviolet-curable resin uniform. The irradiation device 92 is equipped with a mercury lamp or LED as a light source and irradiates the ejected ultraviolet-curable resin with ultraviolet light. As a result, the ejected ultraviolet-curable resin hardens and an insulating resin layer 145 is formed.

[0019] The third molding unit 25 is a unit that molds a connection part on the base 60 that connects the electrode 157A (see Figure 3) of the electronic component 157 and the terminal part 147A of the metal wiring 147, and has a third printing unit 100 and a first heating unit 102. The third printing unit 100 has a dispenser 106 (see Figure 2). The dispenser 106 dispenses conductive resin paste 153 (see Figure 3). The conductive resin paste 153 is, for example, a resin that hardens when heated at a relatively low temperature, in which micrometer-sized metal particles (such as silver particles) are dispersed. The metal particles are, for example, in the form of flakes. The viscosity of the conductive resin paste 153 is higher than that of, for example, metal ink. The metal contained in the metal ink and conductive resin paste 153 is not limited to silver, but may be gold, copper, etc., or multiple types of metals.

[0020] The first heating unit 102 has, for example, a pair of heating plates 108 (see Figure 2) that face each other in the Z-axis direction. The pair of heating plates 108 is a device for heating the conductive resin paste 153 applied by the dispenser 106. For example, the substrate 140 to be manufactured is heated by being sandwiched between the pair of heating plates 108 after the conductive resin paste 153 is dispensed onto the terminal portion 147A of the metal wiring 147. The conductive resin paste 153 hardens due to this heating and is bonded to the terminal portion 147A. Next, the electronic component 157 is mounted on the substrate 140, and the electrodes 157A of the electronic component 157 are placed on the conductive resin paste 153 that has been bonded to the terminal portion 147A. Then, with the electrodes 157A of the electronic component 157 placed on the terminal portion 147A via the conductive resin paste 153, the substrate 140 is heated by being sandwiched between the pair of heating plates 108. When heated, the conductive resin paste 153 hardens and shrinks, causing the flake-shaped metal particles dispersed in the resin to come into contact. This allows the conductive resin paste 153 to exhibit conductivity. The electronic component 157 is electrically connected to the terminal portion 147A via the conductive resin paste 153. Furthermore, the resin in the conductive resin paste 153 is an organic adhesive, and it exhibits adhesive strength when hardened by heating, physically joining the terminal portion 147A (metal wiring 147) and the electrode 157A.

[0021] The above-described heating method for the metal ink and conductive resin paste 153 is merely an example. For example, the conductive resin paste 153 may be heated using an infrared heater. Alternatively, the metal ink may be fired using the heating plate 108. Furthermore, the substrate manufacturing apparatus 10 may also be equipped with heating means other than the infrared irradiation device 78 and the heating plate 108, such as an electric furnace in which the object to be manufactured is placed and heated.

[0022] The mounting unit 27 also has a supply unit 120 and a mounting unit 122. The supply unit 120 is a device that supplies electronic components 157 to be mounted on the substrate 140, and includes, for example, a tape feeder 124. The tape feeder 124 supplies the electronic components 157 to the supply position from a carrier tape on which the electronic components 157 have been tape-formed. Note that the method of supplying the electronic components 157 is not limited to using the tape feeder 124; for example, a tray-type supply device that supplies the electronic components 157 by placing them on a tray may also be used. The supply unit 120 is also capable of supplying probe pins 159 (see Figure 3). These probe pins 159 are made of a metal such as copper or gold and are used, for example, to electrically connect metal wiring 147 in one layer to metal wiring 147 in another layer. Alternatively, the probe pins 159 are used to electrically connect any substrate to another substrate. The method of supplying the probe pins 159 is not particularly limited, but for example, the probe pins 159 may be supplied by placing them on a tray.

[0023] The mounting unit 122 includes a mounting head 126 (see Figure 2) and a moving device 128 (see Figure 2). The mounting head 126 has a suction nozzle (not shown) for adsorbing and holding electronic components 157 and probe pins 159. The suction nozzle adsorbs and holds electronic components 157, etc., by air suction when negative pressure is supplied from a positive / negative pressure supply device (not shown). The suction nozzle also releases the electronic components 157, etc., when a small amount of positive pressure is supplied from the positive / negative pressure supply device. The moving device 128 moves the mounting head 126 between the supply position of the tape feeder 124 and the substrate 140 placed on the base 60. The mounting unit 122 drives the moving device 128 to hold the electronic components 157 supplied from the tape feeder 124 with the suction nozzle of the mounting head 126, and mounts the electronic components 157 held by the mounting head 126 onto the substrate 140.

[0024] As shown in Figure 2, the control device 28 includes a controller 130, a plurality of drive circuits 132, a storage device 133, and an external IF (abbreviation for interface) 135. The controller 130 is a computer-based device equipped with a CPU and is connected to the plurality of drive circuits 132. The plurality of drive circuits 132 are motor amplifiers, etc., and are connected to the electromagnetic motors 38, 56, holding device 62, lifting device 64, inkjet head 76, infrared irradiation device 78, inkjet head 88, flattening device 90, irradiation device 92, dispenser 106, heating plate 108, tape feeder 124, mounting head 126, and moving device 128. The storage device 133 includes, for example, RAM, ROM, flash memory, HDD, etc. The control program 133A is stored in the storage device 133. The controller 130 executes the control program 133A on its CPU and controls the operation of the transport device 20, the first molding unit 22, the second molding unit 24, the third molding unit 25, and the mounting unit 27 via the drive circuit 132. In the following description, the control device 28 that executes the control program 133A on the controller 130 may be referred to simply by its device name. For example, the statement "the control device 28 controls the X-axis sliding mechanism 30" means "the control device 28 executes the control program 133A on the CPU of the controller 130 and controls the X-axis sliding mechanism 30 via the drive circuit 132."

[0025] Furthermore, the external IF 135 is, for example, a LAN IF and is connected to the first management device 138 and the second management device 139 via the local network 137. The first management device 138 is, for example, a device that generates and stores 3D data of a manufacturing object (such as a substrate) to be additively manufactured by the inkjet method. The control device 28 stores the 3D data 133B acquired from the first management device 138 in the storage device 133 and controls the first molding unit 22, etc., based on the 3D data 133B to manufacture the substrate 140. The 3D data 133B includes, for example, data of the substrate 140 (see Figure 3), which is the manufacturing object, sliced ​​layer by layer.

[0026] The second management device 139 is a device that generates and stores job data (control data, so-called recipe) used in the mounting process of mounting electronic components 157 onto the manufactured substrate 140. The control device 28 stores the job data 133C acquired from the second management device 139 in the storage device 133, and based on the job data 133C, determines the type and position of the electronic components 157 to be mounted, and controls the mounting unit 27. Note that the configuration shown in Figure 2 is just one example. The first management device 138 that generates the 3D data 133B and the second management device 139 that generates the job data 133C may be the same device. Also, the substrate manufacturing apparatus 10 may have the function of generating the 3D data 133B and the job data 133C.

[0027] The substrate manufacturing apparatus 10 of this embodiment manufactures a substrate by the configuration described above. The substrate is, for example, a multi-layer substrate 140 as shown in Figure 3. For example, the control device 28 controls the X-axis slide mechanism 30 and the Y-axis slide mechanism 32 to move the stage 52 below the second molding unit 24, and ejects a thin film of ultraviolet-curable resin from the inkjet head 88 of the second printing unit 84 onto the upper surface of the release film 143 on the stage 52. The control device 28 appropriately performs planarization using the planarization device 90, and irradiates the ultraviolet-curable resin with ultraviolet light from the irradiation device 92 to cure it. The control device 28 repeatedly performs ejection, planarization, and curing to form the resin layer 145 shown in Figure 3.

[0028] Next, the control device 28 moves the stage 52 below the first molding unit 22 and ejects metallic ink from the inkjet head 76 of the first printing unit 72 onto the upper surface of the resin layer 145. The control device 28 irradiates the ejected metallic ink with infrared light from the infrared irradiation device 78. For example, the control device 28 ejects metallic ink from the inkjet head 76 while moving the stage 52 in the X direction. After ejecting the metallic ink in one scan in the X-axis direction, the control device 28 sets the infrared irradiation device 78 to a first temperature and heats the ejected metallic ink. This causes some of the organic solvent in the metallic ink to vaporize and dry. The control device 28 considers one scan of ejection and the drying of the ejected metallic ink as one cycle and repeats this cycle to build up the desired thickness. After building up the metallic ink, the control device 28 sets the infrared irradiation device 78 to a second temperature higher than the first temperature and performs firing of the built-up metallic ink. This forms metal wiring 147 on the resin layer 145 with a predetermined thickness (design thickness) and wiring pattern set in the 3D data 133B. The control device 28 may perform the above-described ejection and drying cycle only once (1 cycle) and bake the ejected metal ink at a second temperature. Therefore, the control device 28 may form the metal wiring 147 by baking only one layer of metal ink without stacking it.

[0029] Furthermore, the control device 28 repeatedly performs extrusion, planarization, and curing of UV-curable resin, similar to the first resin layer 145, to form a second resin layer 145 on top of the first resin layer 145. The second resin layer 145 is formed to cover the metal wiring 147 on top of the first resin layer 145. The control device 28 stacks the resin layers 145 and the metal wiring 147 to fabricate a substrate 140 of the desired shape. Also, as shown in Figure 3, the control device 28 forms a cavity 149 in any of the multiple resin layers 145 that exposes a portion of the metal wiring 147 as a terminal portion 147A. In addition, the control device 28 further extrudes metallic ink onto the metal wiring 147 of each layer to form interlayer wiring (vias) 151 that connect to the metal wiring 147 of different layers. Note that instead of using interlayer wiring 151, probe pins 159 may be used to connect the metal wiring 147 of different layers.

[0030] When the control device 28 manufactures the substrate 140 with the cavity 149 provided by the manufacturing process described above, it mounts the electronic components 157. Specifically, for example, after the substrate 140 has been fabricated, the control device 28 controls the third printing unit 100 of the third fabrication unit 25 to extrude conductive resin paste 153 into the terminal portion 147A in the cavity 149. The control device 28 also extrudes conductive resin paste 153 onto the terminal portion 147A exposed in the insertion hole 155 into which the probe pin 159 is inserted. Once the extrusion of the conductive resin paste 153 is complete, for example, the control device 28 places the pallet 141 on which the substrate 140 is placed between a pair of heating plates 108 facing each other in the Z-axis direction and heats the conductive resin paste 153 with the heating plates 108. This causes the conductive resin paste 153 to adhere to the terminal portion 147A.

[0031] Next, the control device 28 moves the stage 52 on which the substrate 140 is placed to the mounting unit 27, and the mounting unit 27 mounts the electronic components 157. At this time, the control device 28 positions the electronic components 157 such that the electrodes 157A of the electronic components 157 are in contact with the conductive resin paste 153 dispensed onto the terminal portion 147A. The control device 28 also controls the mounting unit 27 to insert the probe pins 159, held by the suction nozzles of the mounting portion 122, into the insertion holes 155. Once the placement of the electronic components 157 and probe pins 159 is complete, the control device 28 heats the substrate 140 by sandwiching it from both sides in the Z-axis direction with a pair of heating plates 108, for example, with the electronic components 157 and probe pins 159 positioned on the terminal portion 147A via the conductive resin paste 153. The conductive resin paste 153 hardens, electrically connecting the electrode 157A of the electronic component 157 to the terminal portion 147A, or the probe pin 159 to the terminal portion 147A. This allows for the manufacture of the desired object.

[0032] (Configuration of the first printing section 72) Next, as an example of a metal-containing liquid containing the metal fine particles of this disclosure, we will describe the case in which metal ink discharged from the first printing section 72 of the first molding unit 22 is used. Figure 4 schematically shows the configuration related to the inkjet head 76 of the first printing section 72. As shown in Figure 4, in addition to the inkjet head 76 described above, the first printing section 72 includes first and second tanks 161, 162, a vacuum pump 163, first and second regulators 165, 166, first and second pressure gauges 167, 168, first and second negative pressure supply passages 171, 172, first and second ink flow paths 175, 176, etc.

[0033] Each of the first and second tanks 161 and 162 is capable of storing metallic ink 177. The vacuum pump 163 is a device that changes the pressure in the first and second tanks 161 and 162. The vacuum pump 163 is connected to the first tank 161 via a first negative pressure supply passage 171. The vacuum pump 163 is also connected to the second tank 162 via a second negative pressure supply passage 172. Based on the control of the control device 28 (see Figure 2), the vacuum pump 163 changes the pressure in each of the first and second tanks 161 and 162 and supplies negative or positive pressure to the first and second tanks 161 and 162.

[0034] The first regulator 165 is connected between the vacuum pump 163 and the first negative pressure supply line 171. Based on the control of the control device 28, the first regulator 165 adjusts the pressure inside the first tank 161 to a predetermined level. Similarly, the second regulator 166 is connected between the vacuum pump 163 and the second negative pressure supply line 172. Based on the control of the control device 28, the second regulator 166 adjusts the pressure inside the second tank 162 to a predetermined level.

[0035] The first pressure gauge 167 is a device that detects the pressure in the first negative pressure supply passage 171. The second pressure gauge 168 is a device that detects the pressure in the second negative pressure supply passage 172. Each of the first and second pressure gauges 167 and 168 outputs a signal indicating the detected pressure to the control device 28. Note that each of the first and second pressure gauges 167 and 168 is not limited to a configuration that detects the pressure in a flow path such as the first and second negative pressure supply passages 171 and 172, but may also be configured to detect the pressure in the first and second tanks 161 and 162.

[0036] The control device 28 controls the first regulator 165 based on the signal input from the first pressure gauge 167 to control the pressure in the first tank 161 to a desired level. The control device 28 also controls the second regulator 166 based on the signal input from the second pressure gauge 168 to control the pressure in the second tank 162 to a desired level. Therefore, the control device 28 can individually control the pressures in the first and second tanks 161 and 162. Note that the configuration for individually controlling the pressures in the first and second tanks 161 and 162 is not limited to the configuration shown in Figure 4. For example, the first printing unit 72 may be equipped with two vacuum pumps 163 connected to the first and second tanks 161 and 162, respectively, and the pressures in the first and second tanks 161 and 162 may be individually controlled by controlling each vacuum pump 163.

[0037] The inkjet head 76 also includes an internal flow path 179 and multiple nozzles 181. The first tank 161 is connected to the internal flow path 179 in the inkjet head 76 via a first ink flow path 175. The second tank 162 is also connected to the internal flow path 179 via a second ink flow path 176. Therefore, the first tank 161 is connected to the second tank 162 via the first ink flow path 175, the internal flow path 179, and the second ink flow path 176.

[0038] A solenoid valve 183 is installed in the first ink channel 175. The solenoid valve 183 opens and closes the first ink channel 175 based on the control of the control device 28. Similarly, a solenoid valve 184 is installed in the second ink channel 176, and the control device 28 controls the solenoid valve 184 to switch the opening and closing of the channel. When the solenoid valves 183 and 184 are open, the metallic ink 177 moves between the first and second tanks 161 and 162 and the in-head channel 179 depending on the pressure level.

[0039] The internal flow path 179 in the print head is connected to multiple nozzles 181 and supplies metallic ink 177 supplied from the first and second tanks 161 and 162 to each nozzle 181. When the control device 28 stops the discharge of metallic ink 177 from the nozzles 181, for example, it maintains a predetermined negative pressure inside the first and second tanks 161 and 162. This predetermined negative pressure is, for example, the pressure at which the liquid level of metallic ink 177 is maintained at the opening of the nozzle 181 and metallic ink 177 is not discharged from the nozzle 181.

[0040] Furthermore, when the control device 28 discharges the metallic ink 177 from the nozzle 181, it reduces the negative pressure value in the first and second tanks 161 and 162, or sets the pressure in the first and second tanks 161 and 162 to a predetermined positive pressure. As a result, the metallic ink 177 in the first and second tanks 161 and 162 is supplied to the head internal flow path 179 via the first and second ink flow paths 175 and 176, and discharged from the nozzle 181. The control device 28 controls the discharge amount, discharge speed, etc., of the metallic ink 177 discharged from the nozzle 181 by adjusting the pressure in the first and second tanks 161 and 162.

[0041] Furthermore, the first and second tanks 161 and 162 are each provided with first and second liquid level sensors 185 and 186, respectively. The first liquid level sensor 185 outputs a detection signal to the control device 28 corresponding to the liquid level of the metallic ink 177 stored in the first tank 161. The second liquid level sensor 186 outputs a detection signal to the control device 28 corresponding to the liquid level of the metallic ink 177 stored in the second tank 162. Based on the detection signals from the first and second liquid level sensors 185 and 186, the control device 28 detects the amount of metallic ink 177 in the first and second tanks 161 and 162 (hereinafter referred to as the ink amount).

[0042] Furthermore, a metal ink tank 191 is connected to the first tank 161 via a solenoid valve 189. The control device 28 supplies metal ink 177 from the metal ink tank 191 to the first tank 161 when the amount of ink detected by the first and second liquid level sensors 185 and 186 falls below a predetermined reference ink amount. The control device 28 supplies metal ink 177 from the metal ink tank 191 to the first tank 161 by, for example, opening the solenoid valve 189 to lower the pressure inside the first tank 161. In addition, as will be described later, the control device 28 can circulate (flow back and forth) the metal ink 177 between the first and second tanks 161 and 162 by controlling the pressure inside the first and second tanks 161 and 162. This allows the control device 28 to supply the metal ink 177 supplied to the first tank 161 to the second tank 162. Note that the first printing unit 72 may be equipped with a liquid level sensor only in the first tank 161. In this case, the control device 28 may monitor only the ink level in the first tank 161. Alternatively, the first printing unit 72 may also be configured to connect a metal ink tank to the second tank 162.

[0043] (Regarding the change from metallic ink 177 to solvent-based ink) Here, the metallic ink 177 may dry out, for example, under normal temperature and pressure conditions. For this reason, if the time spent without printing the metallic wiring 147 is extended, the metallic ink 177 in the nozzle 181 of the inkjet head 76 may dry out, and silver particles may adhere to the nozzle 181. As a result, ejection failure may occur, and the metallic wiring 147 may not be able to be properly printed. Therefore, if there is a risk of the metallic ink 177 drying out, such as when the inkjet head 76 is left unused for an extended period, the control device 28 executes a control to discharge the metallic ink 177 from the first and second tanks 161, 162 and the nozzle 181, and to supply solvent into the tanks.

[0044] As shown in Figure 4, the first tank 161 is connected to the solvent tank 194 via a solenoid valve 193. The second tank 162 is connected to the solvent tank 196 via a solenoid valve 195. Solvent is stored in the solvent tanks 194 and 196. This solvent is, for example, a liquid with the same components as the organic solvent contained in the metal ink 177. However, the solvent is not limited to the organic solvent contained in the metal ink 177. As a solvent, for example, a liquid that does not change the properties of the metal ink 177 when mixed with it, or a liquid with high affinity for the metal ink 177 that dissolves the silver particles when mixed with it and does not separate the silver particles of the metal ink 177, can be used. Note that the solvent tanks 194 and 196 may be just one tank. Also, the first printing unit 72 may be configured so that the solvent tank is connected to only one of the first and second tanks 161 and 162.

[0045] First, the control device 28 monitors the time during which the metallic ink 177 is not ejected. For example, if a predetermined upper limit time has elapsed since the end of the previous ejection, the control device 28 executes a control to switch to the solvent. Alternatively, based on the 3D data 133B, the control device 28 may execute a control to switch to the solvent if it is expected that the time during which the metallic wiring 147 is not being fabricated will exceed a predetermined upper limit time.

[0046] Figures 5 to 9 show the control for exchanging the liquid in the first and second tanks 161 and 162. Note that, in order to avoid making the diagrams complicated, Figures 5 to 9 show a simplified representation of the configuration in Figure 4, and the vacuum pump 163 and solenoid valve 183 are omitted from the illustration. When the control device 28 decides to change to a solvent, in step 11 shown in Figure 5 (hereinafter referred to as unit S), it discharges the metal ink 177 from the first and second tanks 161 and 162. The control device 28 closes solenoid valves 189, 193, and 195, and opens solenoid valves 183 and 184, supplying positive pressure to the first and second tanks 161 and 162 to discharge the metal ink 177 from the nozzle 181. The control device 28 continues discharge until it determines, for example, that the metal ink 177 in the first and second tanks 161 and 162 has run out. The control device 28 continues to discharge ink, for example, until the amount of ink detected by the first and second liquid level sensors 185 and 186 becomes zero. Alternatively, the control device 28 may continue to discharge ink for a predetermined time. The control device 28 discharges the metallic ink 177 to, for example, a test area provided on the stage 52 (see Figure 1) or an outlet provided on the substrate manufacturing apparatus 10.

[0047] Next, in S13, the control device 28 closes solenoid valves 189, 183, and 184, and opens solenoid valves 193 and 195, creating negative pressure inside the first and second tanks 161 and 162, and supplying solvent 199 from solvent tanks 194 and 196 to the first and second tanks 161 and 162, respectively. Next, as shown in S15 of Figure 6, the control device 28 circulates the solvent 199 between the first tank 161 and the second tank 162. For example, the control device 28 closes solenoid valves 189, 193, and 195, and opens solenoid valves 183 and 184, alternately switching the pressure inside the first tank 161 and the second tank 162 between positive and negative pressure. When negative pressure is supplied to the first tank 161 and positive pressure is supplied to the second tank 162, the solvent 199 flows from the second tank 162 to the first tank 161 via the inkjet head 76. Conversely, when positive pressure is supplied to the first tank 161 and negative pressure is supplied to the second tank 162, the solvent 199 flows from the first tank 161 to the second tank 162 via the inkjet head 76. As a result, the solvent 199 circulates between the first tank 161 and the second tank 162 via the inkjet head 76. The control device 28 switches between positive and negative pressure a predetermined number of times, and finally maintains negative pressure in the first and second tanks 161 and 162. The first and second tanks 161 and 162 and the inkjet head 76 are then in a state where the solvent 199 is stored (S17). This allows for a change from the metal ink 177 to the solvent 199, and suppresses the occurrence of the adhesion of the silver fine particles described above.

[0048] The above-described modification process and procedures are merely examples. For example, after executing S17, the control device 28 may discharge the solvent 199 and then supply and circulate the solvent 199 again. This allows the tank to be cleaned with the solvent 199 supplied the first time, and new solvent 199 to be stored.

[0049] (Regarding the change from solvent 199 to metallic ink 177) Next, the process of changing the solvent 199 in the first and second tanks 161 and 162 to metallic ink 177 will be described. The control device 28 performs the change to metallic ink 177 before forming the metal wiring 147 using the metallic ink 177. For example, the control device 28 performs the change process shown in Figure 7 and later before the stage 52 moves below the first molding unit 22 in accordance with the formation of the metal wiring 147. First, as shown in S21 of Figure 7, the control device 28 discharges the solvent 199 in the first and second tanks 161 and 162. Similar to S11, the control device 28 supplies positive pressure to the first and second tanks 161 and 162 and continues the discharge process until it is determined that the solvent 199 in the first and second tanks 161 and 162 has been used up.

[0050] Next, the control device 28 closes, for example, solenoid valves 183 and 193 and opens solenoid valve 189 to supply negative pressure to the first tank 161 (S23). Metal ink 177 is supplied from the metal ink tank 191 to the first tank 161. Next, as in S13, the control device 28 closes solenoid valves 189, 193 and 195 and opens solenoid valves 183 and 184 to alternately switch the pressure in the first tank 161 and the second tank 162 between positive and negative pressure (S25 in Figure 8). As a result, the metal ink 177 circulates between the first tank 161 and the second tank 162 through the inkjet head 76 (S25).

[0051] The circulating metallic ink 177 is diluted by the solvent 199 remaining in the first and second tanks 161 and 162. Therefore, after switching between positive and negative pressure a predetermined number of times, the control device 28 supplies positive pressure to the first and second tanks 161 and 162 to discharge the metallic ink 177. The control device 28 stops discharge by supplying negative pressure to the first and second tanks 161 and 162 while a small amount of metallic ink 177 remains in the first and second tanks 161 and 162 (S27 in Figure 8). For example, the control device 28 switches from positive pressure to negative pressure when the amount of metallic ink 177 in the first and second tanks 161 and 162 decreases to a predetermined amount, as detected by the first and second liquid level sensors 185 and 186. Note that the control method for retaining metallic ink 177 is not limited to the method described above. For example, the control device 28 may switch from positive pressure to negative pressure and stop discharge after a predetermined time has elapsed since the start of discharge.

[0052] Here, in S27, if all of the diluted metal ink 177 is discharged (discharged until the tank is empty), air may enter the nozzle 181, potentially causing bubbles to form in the nozzle 181 and the flow path 179 inside the print head. For example, since the metal ink 177 contains a surfactant such as a dispersant that coats the silver nanoparticles, it may foam due to the influx of air. If bubbles are present, the metal ink 177 may not be able to be discharged properly, or the bubbles may splatter and contaminate the surroundings. Therefore, in S27, the control device 28 stops discharging the metal ink 177, leaving a certain amount of ink behind. This suppresses the formation of bubbles in the nozzle 181, etc.

[0053] However, because diluted metal ink 177 remains, even if the supply of metal ink 177 from S29 onward, as described below, is carried out, the silver particles contained in the metal ink 177 in the first and second tanks 161 and 162 may be diluted by the solvent 199 contained in the metal ink 177 remaining in S27 (hereinafter, this may simply be described as "the metal ink 177 is diluted"). When the metal ink 177 is diluted, the thickness of the molded metal wiring 147 will be reduced by the amount by which the concentration of silver particles contained in the metal ink 177 (hereinafter, this may be described as "concentration of silver particles") has decreased. As a result, the metal wiring 147 may not satisfy the desired electrical characteristics. The desired electrical characteristics here refer to the electrical resistance and frequency characteristics required of the circuit.

[0054] To improve this problem, one possible method is to repeatedly discharge S27 and supply the metal ink 177 from S29 onward until the concentration is sufficient to form metal wiring 147 that meets the desired electrical characteristics, that is, until the solvent 199 is depleted. However, this method may increase the amount of waste liquid and lead to increased manufacturing costs. Therefore, the control device 28 performs a correction to increase the number of printing cycles of the metal ink 177 in accordance with the decrease in the concentration of silver fine particles.

[0055] More specifically, after executing S27, the control device 28 supplies metallic ink 177 to the first tank 161 as shown in S29 of Figure 9. The control device 28 closes solenoid valves 183 and 193 and opens solenoid valve 189 to supply negative pressure to the first tank 161 and to supply metallic ink 177 from the metallic ink tank 191 to the first tank 161. Next, the control device 28 switches between positive and negative pressure in the first and second tanks 161 and 162 to circulate the metallic ink 177 between the first tank 161 and the second tank 162 (S31). This makes the concentration of silver particles in the metallic ink 177 in the first and second tanks 161 and 162 and the inkjet head 76 more uniform. The control device 28 performs the switching between positive and negative pressure a predetermined number of times and finally maintains negative pressure in the first and second tanks 161 and 162. As a result, as shown in Figure 4, metallic ink 177 is stored in the first and second tanks 161 and 162 and the inkjet head 76. The control device 28, for example, adjusts the amount of ink in the first and second tanks 161 and 162 to be the same.

[0056] (Shaping of metal wiring 147) Next, the process of creating the metal wiring 147 after changing from the solvent 199 to the metal ink 177 as described above will be explained. Figure 10 shows the relationship between the creation time, silver concentration, and ink volume. The horizontal axis of Figure 10 shows the elapsed time since the first metal wiring 147 was created, for example, when creating multiple metal wirings 147. The vertical axis of the graph above shows the concentration of silver particles in the first and second tanks 161 and 162. The number "1" on this vertical axis indicates a state where the solvent 199 has not been diluted, and below 1 indicates a state where the concentration has been diluted. The lower vertical axis shows the amount of metal ink 177 in the first and second tanks 161 and 162, with higher values ​​on the vertical axis indicating a larger amount of ink.

[0057] For example, suppose that at time T0 in Figure 10, the change from solvent 199 to metal ink 177 has been completed and the molding of metal wiring 147 has begun. At time T0, the concentration of silver particles is X1. The concentration of silver particles in the first and second tanks 161 and 162, which have been processed in S23 to S31 and are ready to dispense metal ink 177 again, is determined by the amount of solvent 199 remaining in the first and second tanks 161 and 162 after the solvent 199 is discharged in S21, the amount supplied from the metal ink tank 191 in S23, the amount of ink left in S27, and the amount supplied from the metal ink tank 191 in S29. In S11, all of the metal ink 177 is discharged. Furthermore, the amount of solvent 199 remaining in the first and second tanks 161 and 162 after the solvent 199 is discharged in S21, for example, the amount of solvent 199 adhering to the inner walls of the tanks and inside the inkjet head 76, can be approximated to a predetermined value. That is, the amount of solvent 199 remaining after discharge in S21 can be considered a constant value.

[0058] Furthermore, the total amount of ink supplied in S23 and the total amount of ink left in both tanks in S27 are set to a constant value. Therefore, the concentration of silver particles in the metal ink 177 left in S27 can be set in advance. The concentration of silver particles after S31 can then be calculated based on this pre-set concentration of silver particles (the concentration of the metal ink 177 left in) and the amount of metal ink 177 supplied in S29. For example, the concentration value of the silver particle concentration in the metal ink 177 left in S27 is pre-set in the memory device 133 (see Figure 2). The control device 28 can detect the amount of metal ink 177 supplied in S29 in Figure 9 based on the detection value of the first liquid level sensor 185 before supply and the detection value after supply. The control device 28 then calculates the concentration X1 of silver particles at time T0 based on the above concentration value and the detected amount of ink.

[0059] The calculation method described above is merely an example. For example, the amount of ink to be left and the concentration of the left-left ink may be stored in the memory device 133 in S27. The control device 28 may calculate the amount of silver particles from the amount of ink to be left and the concentration, and then calculate the concentration after supply from the calculated amount of silver particles and the supply amount in S29. Alternatively, the memory device 133 may store only the concentration and ink amount of the first tank 161, that is, only the values ​​of one of the two tanks. In this case, the control device 28 may, for example, calculate only the concentration of one of the tanks based on half the supply amount in S29 and the concentration value of one of the tanks.

[0060] Next, the control device 28 compares the calculated density X1 with a threshold. In the example shown in Figure 10, a first threshold density TH1 and a second threshold density TH2 are set as thresholds. The first and second threshold densities TH1 and TH2 are pre-set in, for example, the storage device 133. Since the density X1 is less than the first threshold density TH1, the control device 28 increases the number of prints by two layers.

[0061] For example, when the control device 28 fabricates the metal wiring 147, it moves the stage 52 in the X-axis direction and ejects metal ink 177 from the first printing unit 72 to eject one layer of metal ink 177. Next, the control device 28 moves the stage 52 to the firing unit 74 and heats the ejected metal ink 177. As described above, the control device 28 heats and dries the metal ink 177 at a first temperature lower than the second temperature (for example, a temperature about 2 / 3 of the second firing temperature) to vaporize the organic solvent. The control device 28 considers this one layer (one scan) of printing and drying process as one cycle and corrects by increasing the number of cycles according to the concentration. In the case shown in Figure 10, the control device 28 increases the number of cycles by 2 if the concentration X1 is less than the first threshold concentration TH1. As a result, even if the metallic ink 177 is diluted, increasing the number of prints makes it possible to fabricate metallic wiring 147 of the desired thickness, i.e., metallic wiring 147 of the design thickness set in the 3D data 133B. Consequently, metallic wiring 147 with the desired electrical characteristics can be fabricated, and the occurrence of malfunctions of the substrate 140 after manufacturing can be suppressed.

[0062] Similarly, the control device 28 increases the cycle count by one if the calculated density is in the range from the first threshold density TH1 or higher to the second threshold density TH2, which is greater than the first threshold density TH1. This reduces the number of prints required to increase the density as it increases, thereby preventing the metal wiring 147 from becoming excessively thick. The control device 28 may increase only the printing process (number of prints) without increasing both the printing process and the drying process. Alternatively, the control device 28 may perform corrections other than correction of the number of prints. For example, the control device 28 may increase the amount of metal ink 177 ejected from the nozzle 181 in one cycle or one ejection as the density of silver particles decreases. This increases the ejection amount and allows for the creation of metal wiring 147 of the desired thickness. The control device 28 may also perform both correction of the number of prints and correction of the ejection amount. Therefore, the control device 28 performs at least one cycle, with one cycle being the process of ejecting metal ink to the position where the metal wiring 147 is to be created. The control device 28 may perform at least one of the following corrections as a density-dependent process according to the present disclosure: a correction that increases the number of cycle executions in accordance with the decrease in density, and a correction that increases the amount of metal ink 177 ejected per cycle in accordance with the decrease in density, thereby forming a metal wiring 147 of a predetermined thickness. Furthermore, it is preferable to set the correction amount to a correction amount that makes the resistance value of the metal wiring 147 after formation less than or equal to a predetermined resistance value, that is, a correction amount that satisfies the desired electrical characteristics.

[0063] Furthermore, as described above, the control device 28 discharges the solvent 199 (S21, an example of the first discharge process), and after discharge, supplies metal ink 177 into the tank (S23, an example of the first metal-containing liquid supply process). After supplying, the control device 28 discharges the rest of the metal ink 177, leaving a predetermined amount in the tank (S27, an example of the second discharge process), and after discharge, supplies metal ink 177 to the tank (S29, an example of the second metal-containing liquid supply process). In the molding process, the control device 28 calculates the concentration of silver particles stored in the first tank 161 after executing S29, based on the amount of solvent 199 contained in the predetermined amount of metal ink 177 left in S27 and the amount of metal ink 177 supplied in S29. By doing so, by leaving a predetermined amount in S27 and discharging the rest, the generation of foaming caused by the metal ink 177 can be suppressed. Furthermore, by leaving a predetermined amount each time, the processing load for calculating the concentration of silver particles after changing from solvent 199 to metal ink 177 can be reduced. The control device 28 may change the amount of metal ink 177 left in the tank in S27 for each processing step. For example, if the amount of metal ink 177 remaining in the replenishment metal ink tank 191 becomes low, the control device 28 may increase the amount of metal ink 177 left in the tank in S27. This reduces the consumption of metal ink 177. In this case, the number of cycles or the discharge amount may be increased by the amount of the increased remaining amount.

[0064] Furthermore, in S25, the control device 28 circulates the metal ink 177 supplied to the first tank 161 between it and the second tank 162. This allows the solvent 199 remaining in the second tank 162, as well as the first tank 161, to be discharged by the metal ink 177. In addition, in S31, the control device 28 circulates the metal ink 177 supplied to the first tank 161 between it and the second tank 162. This makes the concentration of silver fine particles in the first tank 161 and the second tank 162 more uniform.

[0065] Next, when the amount of ink in the first and second tanks 161 and 162 decreases due to molding, the control device 28 resupplies metal ink 177 from the metal ink tank 191 to the first tank 161. After supplying the metal ink 177, the control device 28 circulates the metal ink 177 between the first tank 161 and the second tank 162, for example, to make the amount of ink in the two tanks the same. The control device 28 recalculates the concentration of silver particles and performs the cycle number correction again. For example, as shown in Figure 10, the amount of ink in the first and second tanks 161 and 162 increases after being supplied at time T0, and then decreases due to the molding of the metal wiring 147. For example, at time T1, when the amount of ink decreases to a predetermined amount, the control device 28 resupplies metal ink 177 to the first tank 161 (an example of a resupply process). The control device 28 performs the supply and circulation of metal ink 177 in the same manner as in S29 and S31. Subsequently, the control device 28 appropriately supplies the metallic ink 177 as the amount of ink decreases (times T2, T3, T4).

[0066] The timing and amount of resupply of the metallic ink 177 are not particularly limited. For example, the control device 28 may supply it as appropriate by determining the idle time in the molding process. In this case, the amount supplied may be changed as appropriate according to the amount of ink remaining in the tank. Alternatively, the control device 28 may supply a predetermined fixed amount of metallic ink 177 when the amount of ink decreases to a predetermined fixed value.

[0067] The control device 28 performs the molding of the metal wiring 147 after resupplying the metal ink 177 (an example of the molding process after resupply). At this time, the control device 28 calculates the concentration of silver particles after resupply based on the concentration of metal particles in the metal ink 177 stored in the first tank 161 before resupply and the amount of resupplied metal ink 177 supplied, and performs the molding process according to the calculated concentration. For example, the calculated concentration X2 at time T1 is greater than or equal to the first threshold concentration TH1 and less than the second threshold concentration TH2. In this case, the control device 28 increases the number of cycles for printing and drying by one cycle. This allows the number of cycles (number of prints) to be reduced in accordance with the increase in concentration due to resupply, and enables the molding of metal wiring 147 of the desired thickness. Note that the control device 28 does not need to change the correction amount as the concentration increases. The control device 28 may use a fixed value as the number of cycles to increase, regardless of the concentration.

[0068] Furthermore, if the calculated density X3 reaches or exceeds the second threshold density TH2 at time T2 after repeated resupply and subsequent molding, the control device 28 stops executing the density-dependent processing. The control device 28 does not perform corrections to increase the number of cycles at time T2 and thereafter (times T3, T4, etc.). As a result, when the density of silver nanoparticles increases to a level where correction is no longer necessary, the correction is terminated, stopping the execution of unnecessary printing processes and preventing the metal wiring 147 from becoming unnecessarily thick. Note that the control device 28 may also terminate the correction based on conditions other than density. For example, the control device 28 may terminate the correction when the number of times resupply has been performed exceeds a predetermined threshold number.

[0069] Incidentally, in the above embodiment, the first printing unit 72 is an example of an ejection device. The inkjet head 76 is an example of a head. The metal ink 177 is an example of a metal-containing liquid containing metal fine particles. S13 is an example of a first supply process and first supply treatment. S21 is an example of a first discharge process. S23 and S25 are examples of a first metal-containing liquid supply process. S27 is an example of a second discharge process. S29 and S31 are examples of a second supply process, second metal-containing liquid supply process and second supply treatment. The first threshold concentration TH1 and second threshold concentration TH2 are examples of threshold concentrations.

[0070] As described above, the following effects are achieved according to the above embodiment. In one embodiment of this system, the control device 28, when fabricating metal wiring 147 using metal ink 177, fabricates metal wiring 147 of a predetermined thickness by performing a process according to the concentration of silver fine particles in the metal ink 177 supplied in S29, which has been diluted with solvent 199 remaining in the first and second tanks 161 and 162. This allows for the fabrication of metal wiring 147 of the designed thickness by performing a process according to the concentration when the metal ink 177 is diluted with solvent 199.

[0071] Furthermore, this disclosure is not limited to the above embodiments, and can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. For example, the content and procedure of the exchange control of the metal ink 177 and solvent 199 shown in Figures 5 to 9 above is just one example. For example, the control device 28 does not have to execute S23, S25, and S27. The control device 28 may execute S29 after S21. In this case, the control device 28 may calculate the concentration of silver particles in the metal ink 177 based on the amount of solvent 199 remaining in the first and second tanks 161 and 162 in S21 and the amount of metal ink 177 supplied in S29. Also, if not executing S23, S25, and S27 results in a larger amount of solvent 199 remaining in the first and second tanks 161 and 162, and the metal ink 177 is further diluted, the control device 28 may perform a correction in the correction of the number of cycles and the amount of discharge to be larger than in the above embodiment. Furthermore, the control device 28 may repeatedly perform the control in S23, S25, and S27 to wash away the solvent 199 in the first and second tanks 161 and 162 with the metal ink 177. In this case, if repeatedly performing the cycles of S23, S25, and S27 reduces the amount of solvent 199 remaining in the first and second tanks 161 and 162 and suppresses the dilution of the metal ink 177, the control device 28 may perform a correction in correcting the number of cycles and the amount of discharge, reducing the correction amount for the number of cycles and the amount of discharge compared to the above embodiment. Furthermore, the control device 28 does not have to execute S31. For example, in forming the metal wiring 147, the control device 28 may dispense the metal ink 177 only from the first tank 161. In this case, for example, in S27, the control device 28 may calculate the concentration of silver particles in the metal ink 177 stored in the first tank 161 after executing S29, based on the concentration of the metal ink 177 remaining in the first tank 161 and the amount of metal ink 177 supplied to the first tank 161 in S29, and perform corrections such as the number of cycles.

[0072] Furthermore, the correction shown in Figure 10 is just one example. For example, the control device 28 does not need to recalculate the concentration of silver particles when it resupplies the metal ink 177 to the first tank 161 (at time T1, for instance). The control device 28 may also maintain the correction amount initially calculated after the exchange of solvent 199 and metal ink 177 (for example, the amount to increase the 2 cycles determined at time T0) even after the resupply of metal ink 177 (after time T1). Alternatively, the control device 28 may recalculate the concentration and adjust the correction amount after a predetermined number of resupply operations, rather than recalculating the concentration each time the metal ink 177 is resupplied to the first tank 161. Furthermore, in the above embodiment, the control device 28 stopped the correction according to the concentration when the calculated concentration reached a predetermined second threshold concentration TH2 or higher, but the correction may be stopped under other conditions. The control device 28 may perform the correction, such as the number of cycles according to the concentration, a preset number of times and then stop the correction. For example, the control device 28 may perform the correction only at time T0 and not perform the correction from time T1 onwards. Alternatively, the control device 28 may perform the correction until time T2 (up to 3 times the metallic ink 177 is supplied) and not perform the correction from time T3 onwards (4 times or more the metallic ink 177 is supplied).

[0073] The number of layers in the substrate 140, the shape of the metal wiring 147, and the number of electronic components 157 shown in Figure 3 are just examples. The first printing unit 72 may be equipped with three or more tanks (such as the first and second tanks 161, 162) for storing the metallic ink 177. The first printing unit 72 may also circulate the metallic ink 177 and solvent 199 through three or more tanks. Alternatively, the first printing unit 72 may be configured to have only one tank for storing the metallic ink 177. Figure 11 shows the configuration of another example of the first printing unit 72A. As shown in Figure 11, the other example of the first printing unit 72A has only a first tank 161. In this case, when exchanging the metallic ink 177 for the solvent 199, the control device 28, for example, as in Figures 5 and 6, decides to change to the solvent 199, and in S11 discharges the metallic ink 177 from the first tank 161, closes the solenoid valves 189 and 183 and opens the solenoid valve 193 in S13 to create negative pressure in the first tank 161 and supply the solvent 199 from the solvent tank 194 to the first tank 161 (an example of the first supply step of this disclosure). Also, after executing S13, for example, the control device 28 supplies positive pressure to the first tank 161 and discharges the solvent 199 from the first tank 161, as in S21 in Figure 7. After discharging the solvent 199, the control device 28 supplies the metallic ink 177 to the first tank 161 in the same manner as S29 in Figure 9 (an example of the second supply step in this disclosure). Then, as shown in Figure 10, when the control device 28 fabricates the metallic wiring 147 using the metallic ink 177, it may fabricate the metallic wiring 147 of a predetermined thickness by performing a process according to the concentration of silver fine particles in the metallic ink 177 supplied in S29, which has been diluted by the solvent 199 remaining in the first tank 161. Even in such a configuration with only one tank, when the metallic ink 177 is diluted by the solvent 199, a process according to the concentration can be performed to fabricate the metallic wiring 147 of the designed thickness.

[0074] The circuit board manufacturing apparatus 10 is equipped with a mounting unit 27 and is configured to perform the mounting of electronic components 157, but it is not necessary to have a mounting unit 27. In this case, the circuit board manufacturing apparatus 10 may perform the manufacturing up to the point of mounting the circuit board 140 before mounting the electronic components 157. Alternatively, the mounting of the electronic components 157 may be performed by a separate device.

[0075] Furthermore, the solenoid valves 183, 184, 189, 193, and 195 that switch between the flow paths are not limited to solenoid valves; for example, they could be of the type that drives the valve using a motor, or piezo valves using a piezoelectric element. Furthermore, although the first printing unit 72 discharged the metallic ink 177 from both the first and second tanks 161 and 162, it may discharge it from at least one of them. For example, if the first printing unit 72 discharges only from the second tank 162, it may close the solenoid valve 183 to create positive pressure in the second tank 162 when discharging the metallic ink 177. Also, the control device 28 may supply metallic ink 177 from the first tank 161 to the second tank 162 when the amount of ink in the second tank 162 decreases. Furthermore, although an ultraviolet-curing resin is used as the resin ejected by the inkjet head 88 in the above embodiment, the invention is not limited to this. For example, a thermosetting resin, a two-component curable resin, a thermoplastic resin, or the like may be used as the resin ejected by the inkjet head 88.

[0076] Furthermore, the contents of this disclosure are not limited to the dependencies described in the claims. For example, this specification also discloses a technical concept in which "the molding method described in claim 1 or claim 2" in claim 5 is changed to "the molding method described in any one of claims 1 to 4". For example, this specification also discloses a technical concept in which "the molding method described in claim 1 or claim 2" in claim 7 is changed to "the molding method described in any one of claims 1 to 6". For example, this specification also discloses a technical concept in which "the molding method described in claim 2" in claim 8 is changed to "the molding method described in claim 2 or any one of claims 3 to 7 that is directly or indirectly dependent on claim 2". [Explanation of symbols]

[0077] 10 Substrate manufacturing equipment (forming equipment), 28 Control device, 72, 72A First printing unit (discharge device), 76 Inkjet head (head), 147 Metal wiring, 161 First tank, 162 Second tank, 177 Metal ink (metal-containing liquid), 199 Solvent, S13 (First supply process, First supply process), S21 (Second supply process, First discharge process, Second supply process), S23, S25 (First metal-containing liquid supply process), S27 (Second supply process, Second discharge process), S29, S31 (Second supply process, Second metal-containing liquid supply process), TH1 First threshold concentration (threshold concentration), TH2 Second threshold concentration (threshold concentration).

Claims

1. A tank capable of storing a metal-containing liquid containing metal fine particles, A head connected to the tank and discharging the metal-containing liquid supplied from the tank, A molding method for forming metal wiring using an extrusion device equipped with the following: A first supply step of supplying a solvent to the tank, After performing the first supply step, a second supply step is performed in which the solvent in the tank is discharged and the metal-containing liquid is supplied to the tank. After performing the second supply step, a molding step is performed in which, when forming a metal wiring using the metal-containing liquid, a metal wiring of a predetermined thickness is formed by a process corresponding to the concentration of metal particles in the metal-containing liquid supplied in the second supply step, which is diluted with the solvent remaining in the tank, A molding method that includes this.

2. In the molding process, The molding method according to claim 1, comprising: performing the process of discharging the metal-containing liquid to a position to form the metal wiring, with each cycle being performed at least once; and performing at least one of the following corrections according to the concentration of metal particles in the metal-containing liquid: a correction that increases the number of cycles performed in accordance with the decrease in concentration; and a correction that increases the amount of metal-containing liquid discharged per cycle in accordance with the decrease in concentration; thereby forming the metal wiring of a predetermined thickness.

3. The second supply step described above is: A first discharge step of discharging the solvent in the tank, After performing the first discharge step, a first metal-containing liquid supply step is performed, in which the metal-containing liquid is supplied to the tank, After performing the first metal-containing liquid supply step, a second discharge step is performed in which a predetermined amount of the metal-containing liquid is left in the tank and the remaining metal-containing liquid is discharged. After performing the second discharge step, a second metal-containing liquid supply step is performed, in which the metal-containing liquid is supplied to the tank. Includes, In the molding process, The molding method according to claim 1 or claim 2, wherein the concentration of metal particles in the metal-containing liquid stored in the tank after the second metal-containing liquid supply step is performed is calculated based on the amount of solvent contained in a predetermined amount of the metal-containing liquid left in the second discharge step and the amount of the metal-containing liquid supplied in the second metal-containing liquid supply step.

4. The at least one of the tanks is Including the first tank and the second tank, In the first metal-containing liquid supply step, The metal-containing liquid is supplied to the first tank, and the metal-containing liquid supplied to the first tank is circulated between the first tank and the second tank. In the second metal-containing liquid supply step, The molding method according to claim 3, comprising supplying the metal-containing liquid to the first tank and circulating the metal-containing liquid supplied to the first tank between it and the second tank.

5. After performing the molding process, a resupply process is performed in which the metal-containing liquid is supplied to the tank, After performing the resupply step, a post-resupply molding step is performed in which the concentration of metal particles in the metal-containing liquid stored in the tank after the resupply step is calculated based on the concentration of metal particles in the metal-containing liquid stored in the tank before the resupply step was performed and the amount of the metal-containing liquid supplied by the resupply step, and the metal wiring of a predetermined thickness is fabricated by processing according to the calculated concentration. A molding method according to claim 1 or claim 2, including the above.

6. In the post-resupply molding process after repeatedly performing the resupply process and the post-resupply molding process, The molding method according to claim 5, wherein if the concentration of the calculation result exceeds a predetermined threshold concentration, the execution of processing corresponding to the concentration of metal fine particles in the metal-containing liquid is stopped.

7. The molding method according to claim 1 or claim 2, wherein the first supply step is performed when the time during which the metal-containing liquid is not discharged is longer than a predetermined threshold time.

8. In the molding process, The molding method according to claim 2, wherein at least one of the corrections, which is a correction that increases the number of cycles executed in accordance with the decrease in concentration and a correction that increases the amount of metal-containing liquid discharged per cycle in accordance with the decrease in concentration, is a correction amount such that the resistance value of the metal wiring after molding is less than or equal to a predetermined resistance value.

9. A tank capable of storing a metal-containing liquid containing metal fine particles, A head connected to the tank and discharging the metal-containing liquid supplied from the tank, Control device and Equipped with, The control device is A first supply process for supplying a solvent to the aforementioned tank, After performing the first supply process, a second supply process is performed in which the solvent in the tank is discharged and the metal-containing liquid is supplied to the tank. After performing the second supply process, when forming metal wiring using the metal-containing liquid, a forming process is performed to form the metal wiring of a predetermined thickness, with a process corresponding to the concentration of metal particles in the metal-containing liquid supplied in the second supply process, which is diluted with the solvent remaining in the tank. A molding device that performs this task.

Images