Method of discharge and forming apparatus

Abstract

To provide a method of discharge allowing for inhibiting an aggregate of bubbles of metal-contained liquid from occurring at a nozzle and a forming apparatus.SOLUTION: A method of discharge in the present disclosure, for discharging metal-containing liquid from a tank in an ejection device comprising at least one tank allowed to reserve metal-containing liquid containing metal particulates and a nozzle connected to the tank and for ejecting the metal-containing liquid supplied from the tank, includes: a discharge-interrupting step that, when discharging metal-containing liquid reserved in a tank from a nozzle, stops discharge in a state that a predetermined volume of metal-containing liquid is left in the tank; a cleaning-liquid supply step that supplies cleaning liquid to the tank after executing the discharge-interrupting step; and a discharge step that discharges the metal-containing liquid left in the tank together with the cleaning liquid from the nozzle after executing the cleaning-liquid supply step.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a technique for discharging a metal-containing liquid that contains metal fine particles from a tank. [Background technology]

[0002] Conventionally, a technique for forming a three-dimensional object by a three-dimensional additive manufacturing method using a metal-containing liquid containing metal fine particles has been proposed. For example, in the following Patent Document 1, a metal-containing liquid is ejected from an inkjet head, and the ejected metal-containing liquid is heated to perform the object forming. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-193236 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned metal-containing liquid may need to be discharged from the tank after a certain period of time has passed due to, for example, the expiration date. When the metal-containing liquid stored in the tank is discharged from the nozzle, if droplets of the metal-containing liquid stick to the nozzle discharge surface and air accompanying the discharge gets into the droplets, there is a risk of foam clumps being generated. The generated foam clumps may then adhere to other units, etc.

[0005] The present disclosure has been made in consideration of such circumstances, and has an objective of providing a discharge method and a molding apparatus that can suppress the formation of bubble clumps in the metal-containing liquid in the nozzle. [Means for solving the problem]

[0006] The present specification discloses a discharge method for discharging a metal-containing liquid from a tank in a discharge device including at least one tank capable of storing a metal-containing liquid containing metal microparticles, and a nozzle connected to the tank and discharging the metal-containing liquid supplied from the tank, the discharge method including: a discharge interruption step of stopping the discharge when discharging the metal-containing liquid stored in the tank from the nozzle while a predetermined amount of the metal-containing liquid remains in the tank; a cleaning liquid supplying step of supplying a cleaning liquid to the tank after performing the discharge interruption step; and a discharge step of discharging the metal-containing liquid remaining in the tank from the nozzle together with the cleaning liquid after performing the cleaning liquid supplying step. For example, the present disclosure is extremely useful when embodied as a molding apparatus that discharges a metal-containing liquid, a control program that controls the molding apparatus to discharge the metal-containing liquid, a storage medium that stores the control program, and the like. Effect of the Invention

[0007] According to the present disclosure, in the discharge interruption step, the discharge is interrupted with only a predetermined amount of the metal-containing liquid remaining in the tank, without discharging all of it. This interrupts the discharge, thereby making it possible to suppress the adhesion of droplets of the metal-containing liquid to the discharge surface of the nozzle and the intrusion of gas into the droplets. Then, after supplying a cleaning liquid into the tank, the metal-containing liquid is discharged together with the cleaning liquid. This allows the metal-containing liquid to be discharged after lowering its viscosity, etc., by diluting it with the cleaning liquid before discharging it, rather than discharging it until the tank is empty while keeping its concentration high. This makes it possible to suppress the occurrence of clumps of foam caused by droplets sticking to the discharge surface of the nozzle. As a result, it is possible to suppress the adhesion of bubbles to other units, etc., and to suppress the occurrence of device failures, etc. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a substrate forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of a substrate forming apparatus. [Diagram 3] 1A and 1B are diagrams illustrating circuit boards produced by the board forming apparatus. [Figure 4] FIG. 2 is a diagram showing a configuration relating to an inkjet head in the first printing unit. [Diagram 5] FIG. 2 is a schematic diagram showing a configuration relating to an inkjet head in a first printing unit. [Figure 6] 13 is a flowchart showing a process for discharging metal ink. [Figure 7] 11A and 11B are diagrams for explaining a process of discharging metal ink. [Figure 8] 11A and 11B are diagrams for explaining a process of discharging metal ink. [Figure 9] 11A and 11B are diagrams for explaining a process of discharging metal ink. [Figure 10] 11A and 11B are diagrams for explaining a process for discharging metal ink in a comparative example. [Figure 11] 13 is a schematic diagram showing a configuration of a first printing unit in a further example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Configuration of substrate forming apparatus 10) Hereinafter, a substrate forming apparatus, which is an embodiment of the modeling apparatus of the present disclosure, will be described with reference to the drawings. FIG. 1 is a schematic diagram of the substrate forming apparatus 10 of this embodiment. FIG. 2 is a block diagram showing a control device 28 of the substrate forming apparatus 10 of this embodiment. As shown in FIGS. 1 and 2, the substrate 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 28 (see FIG. 2). 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 disposed on a base 29 of the substrate forming apparatus 10. The base 29 is generally rectangular in shape, and in the following description, as shown in FIG. 1, the longitudinal direction of the base 29 will be referred to as the X-axis direction, the lateral direction of the base 29 will be referred to as the Y-axis direction, and the direction perpendicular to both the X-axis direction and the Y-axis direction will be referred to 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 a 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. Furthermore, the X-axis slide mechanism 30 includes an electromagnetic motor 38 (see FIG. 2), and the X-axis slider 36 is moved to an arbitrary position in the X-axis direction by driving the electromagnetic motor 38. Furthermore, the Y-axis slide mechanism 32 includes a Y-axis slide rail 50 and a stage 52. The Y-axis slide rail 50 is disposed on a base 29 so as to extend in the Y-axis direction. One end of the Y-axis slide rail 50 in the Y-axis direction is connected to the X-axis slider 36. Therefore, the Y-axis slide rail 50 is movable in the X-axis direction together with 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 56 (see FIG. 2), and the stage 52 is moved to an arbitrary position in the Y-axis direction by driving the electromagnetic motor 56. As a result, the stage 52 is moved to an arbitrary 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, a lifting device 64 (see FIG. 2), and a heater 66 (see FIG. 2). The base 60 is formed in a flat plate shape, and a pallet 61 is placed on the upper surface. The pallet 61 is, for example, a flat metal member. A circuit board is formed on the pallet 61. The holding device 62 is provided on both sides of the base 60 in the X-axis direction. Then, both edges of the pallet 61 placed on the base 60 in the X-axis direction are sandwiched by the holding device 62, thereby fixedly holding the circuit board. The lifting 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 circuit board placed on the base 60 to a desired temperature.

[0012] The first modeling unit 22 is a unit that models the metal wiring of the circuit board, and includes a first printing section 72 and a baking section 74. The first printing section 72 includes an inkjet head 76 (see FIG. 2) that ejects metal ink in a linear shape from the inkjet head 76. The metal ink is a dispersion of nanometer-sized metal particles, such as silver particles, in a solvent (such as an organic 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, for example, by a piezo method using a piezoelectric element. The method of ejecting the metal ink is not limited to the inkjet method using a piezoelectric element, and may be another method, such as a jet dispenser method using a piezoelectric element and air.

[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 to form metal wiring. Note that baking of metal ink is a phenomenon in which, by applying energy, the solvent is evaporated and the protective film for the metal particles, i.e., the dispersant is decomposed, and the metal particles come into contact or fuse together, thereby increasing the conductivity. Then, the metal ink is baked to form metal wiring.

[0014] The second modeling unit 23 is a unit that models a resin layer of a circuit board, 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), which ejects ultraviolet curing resin. The ultraviolet curing resin is a resin that is cured by irradiation with ultraviolet rays. The method by which the inkjet head 88 ejects the ultraviolet curing resin may be, for example, a piezo method using a piezoelectric element, or a thermal method in which resin is heated to generate bubbles and ejected from multiple nozzles.

[0015] The curing section 86 has a flattening device 90 (see FIG. 2) and an irradiation device 92 (see FIG. 2). The flattening device 90 flattens the upper surface of the ultraviolet curing resin discharged by the inkjet head 88, for example, by leveling the surface of the ultraviolet curing resin while scraping off excess resin with a roller or blade, thereby making the thickness of the ultraviolet curing resin uniform. In addition, the irradiation device 92 has a mercury lamp or LED as a light source, and irradiates the discharged ultraviolet curing resin with ultraviolet rays. This causes the discharged ultraviolet curing resin to harden, forming a resin layer.

[0016] The third modeling unit 24 is a unit that models a connection portion between an electrode of an electronic component and a metal wiring, and has a third printing unit 100. The third printing unit 100 has a dispenser 106 (see FIG. 2), which dispenses a conductive paste. The conductive paste is a resin that hardens when heated at a relatively low temperature and has micrometer-sized metal particles (such as silver particles) dispersed in it. The metal particles are in the form of flakes, and the viscosity of the conductive paste is relatively high compared to that of metal ink. The metal contained in the metal ink and the conductive resin paste is not limited to silver, but may be gold, copper, or a plurality of types of metal.

[0017] The conductive paste discharged by the dispenser 106 is heated by the heater 66 built in the base 60. The resin in the heated conductive paste hardens. At this time, the resin in the conductive paste hardens and shrinks, and the flake-shaped metal particles dispersed in the resin 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 by hardening when heated. The above-mentioned method of heating the metal ink and conductive resin paste is an example. For example, the metal ink and conductive paste may be heated using a heating plate. The substrate forming apparatus 10 may also be provided with, as a means for heating the metal ink and conductive paste, an electric furnace in which a molded object is placed and heated.

[0018] The fourth modeling unit 25 is a unit that models a resin for fixing electronic components to a circuit board, and has a fourth printing unit 110. The fourth printing unit 110 has a dispenser 116 (see FIG. 2), which dispenses a thermosetting resin. The thermosetting resin is a resin that hardens when heated, and is a so-called underfill resin. The method by which the dispenser 106 discharges the conductive paste and the method by which the dispenser 116 discharges the thermosetting resin may be, for example, an air pulse method using compressed air, or other methods such as a jet method or a mechanical method. The thermosetting resin discharged 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 electronic components arranged on the circuit board, and includes a driving unit 120 and a heater 121 (see FIG. 2). The pressing unit 26 includes, for example, a pressing member (such as a rubber sheet) that presses the electronic components arranged on the circuit board from above, and drives the driving unit 120 to press the electronic components on the circuit board toward the circuit board with the pressing member. A servo motor, an air cylinder, or the like can be used as the driving unit 120. When the pressing member presses the electronic components (circuit board), a low-friction sheet may be sandwiched between the pressing member and the electronic components. The low-friction sheet is, for example, a sheet made of a material with a low friction coefficient such as PTFE (polytetrafluoroethylene) or fluororesin. By sandwiching the low-friction sheet, the pressing member is slid against the electronic components, and the force acting on the electronic components in the direction of displacement when pressed can be reduced, and the displacement of the electronic components due to pressing can be suppressed.

[0020] Heater 121 includes, for example, an electric heating wire that functions as a heat source, and is provided at a position for heating the pressing member and a position for heating the placement portion on which the circuit board is placed. When the pressing member presses the electronic component, heater 121 heats the pressing member and the circuit board, thereby heating the conductive paste and thermosetting resin described above, and electrically connects and fixes the electronic component to the circuit board.

[0021] Furthermore, mounting unit 27 is a unit that mounts electronic components on a circuit board, and has supply section 130 and mounting section 132. Supply section 130 has, for example, a plurality of tape feeders 134 (see FIG. 2) that feed taped electronic components one by one, and supplies the electronic components at a supply position. Note that supply section 130 is not limited to tape feeder 134, and may be a tray-type supply device that picks up and supplies electronic components from a tray, or the like.

[0022] The mounting unit 132 has a mounting head 136 (see FIG. 2) and a moving device 138 (see FIG. 2) that moves the mounting head 136. The mounting head 136 has a suction nozzle (not shown) for suctioning and holding electronic components. The moving device 138 moves the mounting head 136 between the supply position of electronic components by the tape feeder 134 and the circuit board placed on the base 60. In this way, the mounting unit 132 uses the suction nozzle to suck up the electronic components supplied from the tape feeder 134, and mounts the sucked electronic components on the circuit board.

[0023] 2, substrate forming apparatus 10 includes, as a user interface, for example, a touch panel 139. Touch panel 139 changes the display content under the control of control device 28. Touch panel 139 also outputs a signal to control device 28 in response to an operation input by the user.

[0024] 2, the control device 28 includes a controller 140, a plurality of drive circuits 142, and a storage device 144. Each of the plurality of drive circuits 142 is connected to the electromagnetic motors 38, 56, the holding device 62, the lifting device 64, the heater 66, the inkjet head 76, the infrared ray irradiation device 78, the inkjet head 88, the flattening device 90, the irradiation device 92, the dispensers 106, 116, the drive unit 120, the heater 121, the tape feeder 134, the mounting head 136, the moving device 138, and the touch panel 139. The controller 140 includes a CPU, a ROM, a RAM, and the like, and is mainly a computer, and is connected to the plurality of drive circuits 142. The storage device 144 includes, for example, a RAM, a ROM, a flash memory, and a HDD. A control program 146 is stored in the storage device 144. The controller 140 executes a control program 146 on the CPU and 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, the mounting unit 27, and the touch panel 139 via the drive circuit 142.

[0025] (Formation of circuit boards) Next, an example of a process for forming a circuit board will be described. The board forming apparatus 10 forms a circuit board on the base 60 by the above-mentioned configuration. In the following description, a case where a circuit board 151 shown in FIG. 3 is formed will be described. Also, the devices controlled by the control device 28 may be described simply by the device name. For example, the description "the stage 52 moves below the second modeling unit 23" means that "the stage 52 moves below the second modeling unit 23 by controlling the electromagnetic motor 38 of the X-axis slide mechanism 30 and the electromagnetic motor 56 of the Y-axis slide mechanism 32 based on the control of the control device 28."

[0026] First, for example, a release film 153 is attached on the pallet 61 of the stage 52. The circuit board 151, which is a model, is modeled on the release film 153. The release film 153 is a film whose adhesiveness decreases at a predetermined temperature or higher, and which becomes easy to peel off from the pallet 61. The control device 28 moves the pallet 61 (stage 52) to each unit to perform formation. For example, when the formation work is started, first, the stage 52 moves to below the second modeling unit 23. The second modeling unit 23 forms a resin laminate 155 on the release film 153 by repeatedly executing a process of discharging ultraviolet curing resin from the inkjet head 88 onto the release film 153 and a process of irradiating the discharged ultraviolet curing resin with ultraviolet rays by the irradiation device 92. In the formation of the resin laminate 155, the second modeling unit 23 appropriately performs flattening by the flattening device 90 of the curing section 86.

[0027] Next, in the first printing section 72 of the first modeling unit 22, the inkjet head 76 ejects metal ink in lines according to the circuit pattern onto the upper surface of the resin laminate 155. Then, in the baking section 74, the infrared irradiation device 78 irradiates the ejected metal ink with infrared rays to bake the metal ink, thereby forming metal wiring 157 on the upper surface of the resin laminate 155 (an example of the metal wiring forming process of the present application).

[0028] Next, in the second modeling unit 23, similar to the formation of the resin layered body 155 described above, the ejection of the ultraviolet curable resin and the irradiation of ultraviolet rays are repeatedly performed to form a resin layered body 159 on the metal wiring 157. The second modeling unit 23 forms the resin layered body 159 so that, for example, the ends of the metal wiring 157 are exposed. The step portion between the resin layered body 155 and the resin layered body 159 functions as a cavity.

[0029] Next, in the third printing unit 100 of the third modeling unit 24, the dispenser 106 dispenses conductive paste onto the end of the metal wiring 157. Next, in the fourth printing unit 110 of the fourth modeling unit 25, the dispenser 116 dispenses thermosetting resin 161 onto the upper surface of the resin laminate 155 between the ends of the metal wiring 157. Next, the mounting unit 27 supplies an electronic component 163 by the tape feeder 134 and holds the electronic component 163 by the suction nozzle of the mounting head 136. The mounting head 136 is moved by the moving device 138, and mounts the electronic component 163 held by the suction nozzle so that the electrode 165 of the electronic component 163 and the metal wiring 157 are electrically connected. The electrode 165 is disposed so as to be in contact with the conductive paste dispensed onto the metal wiring 157 and uncured. Furthermore, the lower surface of the electronic component 163 comes into contact with the uncured thermosetting resin 161 dispensed between the metal wirings 157. The thermosetting resin 161 is sealed between the upper surface of the resin laminate 155 and the lower surface of the electronic component 163.

[0030] Next, the stage 52 moves below the pressing unit 26. The pressing unit 26 drives the driving section 120 to, for example, raise the pallet 61 and press it against the pressing member, and the pressing member presses the electronic component 163 toward the resin laminate 155. The pressing unit 26 may be configured to lower the pressing member to press the electronic component 163. When pressing, the pressing member presses the electronic component via the low friction sheet described above. This suppresses the positional deviation of the electronic component 163 when pressed. In addition, when pressing the electronic component 163, the pressing unit 26 performs heating by the heater 121, and heats and hardens the conductive paste and the thermosetting resin 161. The conductive paste is heated and hardened in a compressed state to exhibit conductivity, and electrically connects the electronic component 163 to the metal wiring 157. Therefore, the hardened conductive paste functions as the bump 167. Furthermore, by being pressed, electronic component 163 and thermosetting resin 161 are brought into close contact with each other, and electrodes 165 and the conductive paste are also brought into close contact with each other. As a result, electronic component 163 is fixed to the upper surface of resin laminate 155 by the adhesive force of thermosetting resin 161.

[0031] When the pressing by the pressing unit 26 is completed, the stage 52 moves to below the fourth modeling unit 25. In the fourth printing section 110 of the fourth modeling unit 25, the dispenser 116 dispenses the thermosetting resin 169 so as to cover the side surface of the electronic component 163. Then, the heater 66 built in the base 60 heats the resin laminate 155. As a result, the thermosetting resin 169 is heated and hardened through the resin laminate 155. Therefore, the thermosetting resin 161 is sealed between the upper surface of the resin laminate 155 and the lower surface of the electronic component 163, and the thermosetting resin 169 hardens in a state of covering the side surface of the electronic component 163. In this way, the circuit board 151 is manufactured. Note that the materials used in the manufacturing process and the contents and order of the processes are merely examples, and may be changed as appropriate depending on the object to be manufactured.

[0032] (Configuration of the first printing unit 72) Next, a case where a metal ink discharged from the first printing unit 72 is adopted as an example of the metal-containing liquid containing metal fine particles of the present disclosure will be described. FIG. 4 is a schematic diagram showing the configuration of the inkjet head 76 of the first printing unit 72. As shown in FIG. 4, the first printing unit 72 includes, in addition to the inkjet head 76 described above, first and second tanks 171A and 171B, a positive pressure pump 173, a negative pressure pump 174, first and second regulators 175 and 176, and first and second pressure gauges 177 and 178. The first tank 171A is different from the second tank 171B in that it includes an ink supply passage 179 to be described later, but is otherwise configured similarly to the second tank 171B. For this reason, in the following description, the first tank 171A will be mainly described, and the description of the second tank 171B will be omitted as appropriate. In addition, the letter "A" is added to the end of the reference numerals of the members related to the first tank 171A, and the corresponding members related to the second tank 171B are given reference numerals of the same number and the letter "B" is added to the end.

[0033] Each of the first and second tanks 171A, 171B has, for example, a vertically long cylindrical shape and is capable of storing metal ink 181. The positive pressure pump 173 is a pump that supplies positive pressure gas to each of the first and second tanks 171A, 171B. The negative pressure pump 174 is a pump that supplies negative pressure gas to each of the first and second tanks 171A, 171B. The gas supplied by the positive pressure pump 173 and the negative pressure pump 174 can be air, but specific gases such as oxygen and nitrogen may also be used.

[0034] The positive pressure pump 173 is connected to the first tank 171A via a first positive pressure supply passage 183A, and is connected to the second tank 171B via a second positive pressure supply passage 183B. The negative pressure pump 174 is connected to the first tank 171A via a first negative pressure supply passage 184A, and is connected to the second tank 171B via a second negative pressure supply passage 184B. The first tank 171A is provided with a first air supply port 185A that supplies air. The positive pressure pump 173 supplies positive pressure air from the first air supply port 185A to the first tank 171A via the first positive pressure supply passage 183A. The negative pressure pump 174 supplies negative pressure air from the first air supply port 185A to the first tank 171A via the first negative pressure supply passage 184A. Similarly, a second air supply port 185B of the second tank 171B is connected to each of a second positive pressure supply path 183B and a second negative pressure supply path 184B.

[0035] The positive pressure pump 173 changes the pressure (positive pressure) of the air to be supplied based on the control of the control device 28 (see FIG. 2). The first regulator 175 is connected between the positive pressure pump 173 and the first and second positive pressure supply paths 183A and 183B. The first regulator 175 adjusts the pressure of the air supplied from the positive pressure pump 173 to the first and second positive pressure supply paths 183A and 183B, i.e., the pressure of the air supplied to the first and second tanks 171A and 171B, to a desired positive pressure based on the control of the control device 28. The first pressure gauge 177 is a device that detects the pressure of the air supplied from the first regulator 175 to the first and second positive pressure supply paths 183A and 183B. The first pressure gauge 177 outputs a signal indicating the detected pressure to the control device 28. The control device 28 controls the first regulator 175 and the like based on a signal input from the first pressure gauge 177, and sets the insides of the first and second tanks 171A, 171B to a desired positive pressure.

[0036] Similarly, the negative pressure pump 174 changes the pressure (negative pressure) of the air to be supplied based on the control of the control device 28. The second regulator 176 is connected between the negative pressure pump 174 and the first and second negative pressure supply paths 184A, 184B. The second regulator 176 adjusts the pressure of the air supplied from the negative pressure pump 174 to the first and second negative pressure supply paths 184A, 184B, i.e., the pressure of the air supplied to the first and second tanks 171A, 171B, to a desired negative pressure based on the control of the control device 28. The second pressure gauge 178 is a device that detects the pressure of the air supplied from the second regulator 176 to the first and second negative pressure supply paths 184A, 184B. The second pressure gauge 178 outputs a signal indicating the detected pressure to the control device 28. The control device 28 controls the second regulator 176 etc. based on a signal input from the second pressure gauge 178 to set the inside of the first and second tanks 171A, 171B to a desired negative pressure. Note that the first and second pressure gauges 177, 178 are not limited to a configuration for detecting the pressure of a flow path such as the first and second positive pressure supply paths 183A, 183B and the first and second negative pressure supply paths 184A, 184B, but may be a configuration for detecting the pressure inside the first and second tanks 171A, 171B.

[0037] A first solenoid valve 187A is connected between the first positive pressure supply passage 183A and the positive pressure pump 173, and a first solenoid valve 187B is connected between the second positive pressure supply passage 183B and the positive pressure pump 173. A second solenoid valve 188A is connected between the first negative pressure supply passage 184A and the negative pressure pump 174, and a second solenoid valve 188B is connected between the second negative pressure supply passage 184B and the negative pressure pump 174. The first solenoid valves 187A, 187B, the second solenoid valves 188A, 188B, and other solenoid valves (third solenoid valves 189A, 189B, fourth solenoid valve 193, nozzle solenoid valves 201A, 201B) described later are, for example, solenoid valves.

[0038] The first solenoid valve 187A opens and closes the first positive pressure supply path 183A based on the control of the control device 28. Similarly, the first solenoid valve 187B and the second solenoid valves 188A and 188B open and close the second positive pressure supply path 183B, the first negative pressure supply path 184A, and the second negative pressure supply path 184B based on the control of the control device 28. As a result, the control device 28 controls the positive pressure pump 173, the negative pressure pump 174, the first solenoid valves 187A and 187B, and the second solenoid valves 188A and 188B, etc., to individually control the pressures in the first and second tanks 171A and 171B. Note that the configuration for individually controlling the pressures of the first and second tanks 171A and 171B is not limited to the configuration shown in FIG. 4. For example, the first printing unit 72 may be provided with two positive pressure pumps 173 connected to the first and second tanks 171A, 171B, respectively, and the pressure of each of the first and second tanks 171A, 171B may be individually controlled by controlling each positive pressure pump 173.

[0039] The first air supply port 185A is connected to the outside via the third solenoid valve 189A, and can take in air from outside the device. The control device 28 opens the third solenoid valve 189A to set the pressure in the first tank 171A to atmospheric pressure. Similarly, the second air supply port 185B is connected to the outside via the third solenoid valve 189B, and supplies atmospheric pressure to the second tank 171B in response to the opening of the third solenoid valve 189B. In the following description, setting the pressure in the first tank 171A to positive pressure, negative pressure, or atmospheric pressure will simply be described as "setting the first tank 171A to positive pressure" and the like. In addition, when any one of the first solenoid valve 187A, the second solenoid valve 188A, and the third solenoid valve 189A is opened, the other two solenoid valves are closed. Therefore, for example, when the first tank 171A is set to a positive pressure, the control device 28 opens only the first solenoid valve 187A and closes the second solenoid valve 188A and the third solenoid valve 189A. In the following description, the description of the opening and closing control of the first to third solenoid valves 187A, 188A, and 189A when the first tank 171A is set to a positive pressure, a negative pressure, or atmospheric pressure may be omitted. The same applies to the second tank 171B. The control device 28 may execute control to simultaneously open at least two of the first solenoid valve 187A, the second solenoid valve 188A, and the third solenoid valve 189A, and control the positive pressure pump 173, the negative pressure pump 174, etc. to adjust the pressure in the first tank 171A.

[0040] The first printing unit 72 also includes a cleaning liquid tank 195 capable of storing cleaning liquid 197. The first tank 171A is provided with a first cleaning liquid supply port 191A for supplying the cleaning liquid 197. The first cleaning liquid supply port 191A is provided below the first air supply port 185A in the first tank 171A. The first cleaning liquid supply port 191A may be provided at the same height as the first air supply port 185A or at a position above the first air supply port 185A. Similarly, the second tank 171B is provided with a second cleaning liquid supply port 191B for supplying the cleaning liquid 197 at a position below the second air supply port 185B.

[0041] A fourth solenoid valve 193 is connected to the discharge port of the cleaning liquid tank 195. A three-way valve 194 is connected to the fourth solenoid valve 193. In addition to the fourth solenoid valve 193, a first cleaning liquid supply port 191A and a second cleaning liquid supply port 191B are connected to the three-way valve 194. The three-way valve 194 is a switching valve, and is switched between a state in which the fourth solenoid valve 193 (cleaning liquid tank 195) is connected to the first cleaning liquid supply port 191A and a state in which the fourth solenoid valve 193 is connected to the second cleaning liquid supply port 191B based on the control of the control device 28. In this way, by limiting the tank that can be connected to the cleaning liquid tank 195 at one time to either the first or second tank 171A or 171B, it becomes easy to control the supply amount of the cleaning liquid 197.

[0042] The above-mentioned connection configuration between the first and second tanks 171A, 171B and the cleaning liquid tank 195 is an example. For example, the first and second cleaning liquid supply ports 191A, 191B may be connected to the cleaning liquid tank 195 by separate flow paths. For example, the first cleaning liquid supply port 191A may be connected to the cleaning liquid tank 195 via a fourth solenoid valve 193, and the second cleaning liquid supply port 191B may be connected to the cleaning liquid tank 195 via another fourth solenoid valve. In this case, the three-way valve 194 may be eliminated. Also, the cleaning liquid 197 can be supplied from the cleaning liquid tank 195 to the first and second tanks 171A, 171B at the same time.

[0043] The cleaning liquid 197 is a liquid for washing away the metal ink 181 in the first and second tanks 171A and 171B. The control device 28 switches the three-way valve 194 to the first tank 171A side, opens the fourth solenoid valve 193, and creates a negative pressure in the first tank 171A, thereby supplying the cleaning liquid 197 from the cleaning liquid tank 195 into the first tank 171A. The control device 28 drives the negative pressure pump 174 and the second regulator 176 to adjust the negative pressure in the first tank 171A, thereby adjusting the supply amount of the cleaning liquid 197 supplied from the cleaning liquid tank 195 to the first tank 171A. Similarly, the control device 28 switches the three-way valve 194 to the second tank 171B side, opens the fourth solenoid valve 193, and creates a negative pressure in the second tank 171B, thereby supplying the cleaning liquid 197 from the cleaning liquid tank 195 into the second tank 171B.

[0044] Therefore, as described later, the first and second tanks 171A, 171B store metal ink 181, cleaning liquid 197, or a mixture thereof, depending on the time and situation. In the following description, the liquid stored in the first and second tanks 171A, 171B may be collectively referred to as stored liquid. The first printing unit 72 may include a cleaning liquid tank 195 that supplies cleaning liquid 197 to the second tank 171B, in addition to the cleaning liquid tank 195 that supplies cleaning liquid 197 to the first tank 171A. The first printing unit 72 may also be configured such that the cleaning liquid tank 195 is connected to only one of the first and second tanks 171A, 171B.

[0045] FIG. 5 is a schematic diagram of the inkjet head 76. As shown in FIG. 4 and FIG. 5, the inkjet head 76 includes nozzle solenoid valves 201A and 201B, first nozzle flow paths 203A and 203B, and a nozzle section 205. The first tank 171A is connected to the nozzle solenoid valve 201A of the inkjet head 76 via a tank flow path 207A. The nozzle solenoid valve 201A is connected to the nozzle section 205 via the first nozzle flow path 203A. Similarly, the second tank 171B is connected to the nozzle section 205 via a tank flow path 207B, the nozzle solenoid valve 201B, and the first nozzle flow path 203B. The nozzle solenoid valves 201A and 201B are opened and closed based on the control of the control device 28 to open and close the flow paths.

[0046] The nozzle section 205 includes a second nozzle flow path 207 (see FIG. 5) and a plurality of nozzles 209 (see FIG. 5). The first nozzle flow paths 203A and 203B are connected to the second nozzle flow path 207. Therefore, the first tank 171A is connected to the second tank 171B via the tank flow path 207A, the first nozzle flow path 203A, the second nozzle flow path 207, the first nozzle flow path 203B, and the tank flow path 207B. In addition, the plurality of nozzles 209 are connected to the second nozzle flow path 207. Therefore, the plurality of nozzles 209 eject the metal ink 181 or the cleaning liquid 197 supplied via the second nozzle flow path 207 from the first tank 171A, the second tank 171B, or both of them.

[0047] When the nozzle solenoid valves 201A and 201B are open, the stored liquid moves between the first and second tanks 171A and 171B depending on the pressure in the first and second tanks 171A and 171B. The control device 28 transfers the stored liquid between the first and second tanks 171A and 171B via the second nozzle flow path 207. For example, when transferring the stored liquid from the first tank 171A to the second tank 171B, the control device 28 opens the nozzle solenoid valves 201A and 201B, opens the third solenoid valve 189A to set the first tank 171A to atmospheric pressure, and opens the second solenoid valve 188B to set the second tank 171B to negative pressure. As a result, the stored liquid in the first tank 171A flows into the second tank 171B via the second nozzle flow path 207 of the nozzle portion 205. Similarly, when the stored liquid is sent from the second tank 171B to the first tank 171A, the control device 28 sets the second tank 171B to atmospheric pressure and sets the first tank 171A to negative pressure. The control device 28 switches between atmospheric pressure and negative pressure in this way, and executes an operation of returning the stored liquid sent from one of the first and second tanks 171A and 171B to the other tank from the other tank to the one tank again (hereinafter, this may be referred to as circulation). Note that the above-mentioned control content of the circulation operation is one example. For example, when the stored liquid is sent from the first tank 171A to the second tank 171B, the control device 28 may open the first solenoid valve 187A to set the first tank 171A to positive pressure and open the second solenoid valve 188B to set the second tank 171B to negative pressure.

[0048] Furthermore, when the metal ink 181 is discharged from the nozzles 209 to form the metal wiring 157, for example, the control device 28 opens the nozzle solenoid valves 201A, 201B to fill the inkjet head 76 with the metal ink 181. The control device 28 discharges the metal ink 181 from the multiple nozzles 209 by vibrating a piezoelectric element (not shown) while maintaining a predetermined negative pressure in the first and second tanks 171A, 171B. This predetermined negative pressure is, for example, a pressure at which the liquid level of the metal ink 181 is maintained at the opening of the nozzle 209 and the metal ink 181 does not leak from the nozzle 209. The control device 28 may perform discharge by adjusting the pressure in the first and second tanks 171A, 171B in addition to or without using a piezoelectric element.

[0049] The first tank 171A is provided with an ink supply path 179 for refilling the metal ink 181. The ink supply path 179 is, for example, a flow path (pipe) formed penetrating from the side surface of the cylindrical first tank 171A to the outside and extending obliquely upward from the side surface of the first tank 171A. A lower opening of the ink supply path 179 communicates with the first tank 171A and is provided below the first air supply port 185A and above the first cleaning liquid supply port 191A in the vertical direction. An ink supply unit 211 is attached to an upper opening of the ink supply path 179.

[0050] The ink supply unit 211 is, for example, a cover of the ink supply path 179, and is detachable from the opening of the ink supply path 179. The user removes the ink supply unit 211 and refills the first tank 171A with the metal ink 181 via the ink supply path 179. The refilling of the metal ink 181 may be performed automatically. For example, the substrate forming apparatus 10 may include an ink tank capable of storing the metal ink 181. The first tank 171A may be connected to the ink tank storing the metal ink 181, and the first tank 171A may be refilled with the metal ink 181 from the ink tank by applying negative pressure to the first tank 171A in the same manner as the cleaning liquid tank 195.

[0051] The first printing unit 72 is also provided with a first liquid sensor 213A and a second liquid sensor 213B. A first lens 215A is attached to the upper surface of the first tank 171A, and a second lens 215B is attached to the upper surface of the second tank 171B. The first liquid sensor 213A is, for example, an optical liquid level sensor, and is attached above the first tank 171A. The first liquid sensor 213A outputs a detection signal corresponding to the height of the liquid level to the control device 28 based on the reflected light reflected by the liquid surface of the stored liquid in the first tank 171A via the first lens 215A. Similarly, the second liquid sensor 213B outputs a detection signal corresponding to the height of the liquid level to the control device 28 based on the reflected light reflected by the liquid surface of the stored liquid in the second tank 171B via the second lens 215B. This allows the control device 28 to detect the amount of liquid stored in each of the first and second tanks 171A, 171B and to execute control in accordance with the amount.

[0052] The first and second liquid sensors 213A and 213B are examples of the liquid sensor of the present application. The liquid sensor of the present application is not limited to an optical liquid level sensor. For example, it may be a sensor that detects the height of the liquid level or the amount of stored liquid using ultrasonic waves or electromagnetic waves. Alternatively, it is not limited to a non-contact sensor, and it may be a sensor that detects the liquid level using an electrode or a light receiving element inserted into the liquid. Alternatively, a flow rate sensor that detects the amount of stored liquid flowing through the tank flow path 207A may be provided, and the amount of stored liquid may be detected by moving the stored liquid between the first and second tanks 171A and 171B. Also, the first printing unit 72 may be configured to include the first liquid sensor 213A and not include the second liquid sensor 213B.

[0053] As shown in FIG. 5, in this embodiment, an upper limit value TH1A and a lower limit value TH2A are set to determine the height of the liquid level of the stored liquid in the first tank 171A. The upper limit value TH1A is set, for example, at a position that is a predetermined distance below the position of the first cleaning liquid supply port 191A. The lower limit value TH2A is set at a position that is lower than the upper limit value TH1A. Similarly, an upper limit value TH1B and a lower limit value TH2B are set to determine the height of the liquid level of the stored liquid in the second tank 171B. In this embodiment, the first and second tanks 171A and 171B have the same configuration. Therefore, the upper limit values ​​TH1A and TH1B are the same height, and the lower limit values ​​TH2A and TH2B are the same height.

[0054] The control device 28 prompts the refilling of the metal ink 181 when at least one of a first condition that the liquid level of the metal ink 181 in the first tank 171A falls below a lower limit value TH2A and a second condition that the liquid level of the metal ink 181 in the second tank 171B falls below a lower limit value TH2B is satisfied before starting production of the circuit board 151. For example, when at least one of the first and second conditions is satisfied, the control device 28 displays a message such as "Please refill the metal ink" on the touch panel 139 before starting production. In the following description, an expression such as "the liquid level of the metal ink 181 falls below the lower limit value TH2A" may be simply expressed as "the metal ink 181 falls below the lower limit value TH2A".

[0055] Alternatively, the control device 28 may prompt the replenishment before starting the production of the circuit board 151 when at least one of the first and second conditions is expected to be satisfied during production based on the usage amount of the metal ink 181 in the circuit board 151 to be produced before starting the production of the circuit board 151. Furthermore, the control device 28 may prompt the replenishment of the metal ink 181 before starting the next production when at least one of the first and second conditions is satisfied during the production of the circuit board 151. For this reason, the lower limit values ​​TH2A and TH2B are preferably values ​​that can ensure an amount of the metal ink 181 sufficient to complete one production of the circuit board 151 even if the metal ink 181 reaches the lower limit values ​​TH2A and TH2B simultaneously with the start of production. The lower limit values ​​TH2A and TH2B can be set to an average usage amount, a minimum usage amount, a maximum usage amount, or the like of the metal ink 181 used in one production. In other words, as long as the metal ink 181 of the lower limit values ​​TH2A, TH2B is stored in both the first and second tanks 171A, 171B, one production run of the circuit board 151 is possible.

[0056] The above-mentioned setting criteria and purposes of use of the lower limits TH2A and TH2B are merely examples. For example, if the first printing unit 72 is equipped with only the first liquid sensor 213A, the control device 28 may determine whether to notify the refill of the metal ink 181 using only the first liquid sensor 213A and the lower limit TH2A. The control device 28 may also notify the refill of the metal ink 181 during production of the circuit board 151. If the board forming apparatus 10 can automatically refill the metal ink 181, the control device 28 may automatically refill the metal ink 181 based on the fact that the metal ink 181 falls below the lower limit TH2A or TH2B during or after production of the circuit board 151.

[0057] The lower limit values ​​TH2A and TH2B are also utilized in the circulation operation of the stored liquid. For example, when the user completes the work of refilling the first tank 171A with the metal ink 181 from the ink supply path 179, the user executes an operation to the effect that the refilling is completed on the touch panel 139. Based on the operation on the touch panel 139, the control device 28 circulates the metal ink 181 refilled in the first tank 171A between the first tank 171A and the second tank 171B. At this time, when the control device 28 sends the metal ink 181 from the first tank 171A to the second tank 171B, for example, the control device 28 sends the metal ink 181 until the metal ink 181 in the first tank 171A reaches the lower limit value TH2A. When the metal ink 181 reaches the lower limit value TH2A, the control device 28 switches the first tank 171A from atmospheric pressure to negative pressure and switches the second tank 171B from negative pressure to atmospheric pressure. After performing this circulation operation several times, the control device 28 applies negative pressure to both the first and second tanks 171A, 171B. By applying the same negative pressure to the first and second tanks 171A, 171B, the same amount of metal ink 181 is stored in both the first and second tanks 171A, 171B. This completes the refilling of the metal ink 181. Note that the control device 28 may control the circulation using the above-mentioned lower limit values ​​TH2A, TH2B not only for the circulation of the metal ink 181, but also for the circulation of the cleaning liquid 197 and the circulation of a mixture of the metal ink 181 and the cleaning liquid 197.

[0058] Furthermore, when at least one of a third condition that the height of the stored liquid in the first tank 171A exceeds the upper limit value TH1A and a fourth condition that the stored liquid in the second tank 171B exceeds the upper limit value TH1B is satisfied, the control device 28 discharges (purges) the stored liquid. As the timing for determining the third and fourth conditions, the timing after the metal ink 181 is refilled or the timing after an instruction to start the production of the circuit board 151 is received until the production is started can be adopted. For example, when the control device 28 receives an operation of the touch panel 139 indicating that the above-mentioned refilling is completed, the control device 28 determines whether the metal ink 181 in the first tank 171A is equal to or greater than the upper limit value TH1A. When the metal ink 181 is equal to or greater than the upper limit value TH1A, the control device 28 opens the nozzle solenoid valve 201A to apply a positive pressure to the first tank 171A, and discharges the metal ink 181 from the nozzle 209 until the height of the liquid surface becomes less than the upper limit value TH1A. Similarly, for example, after supplying the cleaning liquid 197 to the first tank 171A, if the cleaning liquid 197 in the first tank 171A is equal to or greater than the upper limit value TH1A, the control device 28 drains the cleaning liquid 197. Furthermore, for example, when the control device 28 receives an instruction to start production of the circuit board 151 via the touch panel 139, the control device 28 may determine whether the metal ink 181 in the first tank 171A is equal to or greater than the upper limit value TH1A, and if it is equal to or greater than the upper limit value TH1A, perform drainage.

[0059] The destination of the stored liquid is not particularly limited, and for example, a box for discharging the stored liquid may be provided in the first printing unit 72. The inkjet head 76 of the first printing unit 72 is, for example, slidable within a certain range and can be moved between an area for forming the circuit board 151 and a position for discharging the stored liquid. The above-mentioned box may be provided at the position for discharging the stored liquid, and the inkjet head 76 may be moved to the position for discharging in response to the discharging operation. Alternatively, a box for discharging the stored liquid and a discharge port connected to the box may be provided in the base 60.

[0060] The above-mentioned method of using the upper limit values ​​TH1A, TH1B and the lower limit values ​​TH2A, TH2B is an example. For example, the upper limit values ​​TH1A, TH1B may be used in the circulation operation of the stored liquid. For example, when the controller 28 sends the stored liquid from the first tank 171A to the second tank 171B, the controller 28 may send the stored liquid until the stored liquid in the second tank 171B reaches the upper limit value TH1B. Also, when the controller 28 sends the stored liquid from the first tank 171A to the second tank 171B, if the stored liquid in the second tank 171B is equal to or greater than the upper limit value TH1B after the stored liquid in the first tank 171A reaches the lower limit value TH2A and the sending operation is stopped, the controller 28 may drain the stored liquid in the second tank 171B to the upper limit value TH1B.

[0061] (Regarding the discharge of metallic ink 181) FIG. 6 shows a flowchart of a process for discharging the metal ink 181. Here, the metal ink 181 may have a set expiration date. If the expiration date passes, there is a risk that the printing accuracy and the electrical characteristics of the formed metal wiring 157 may deteriorate. For example, the expiration date of the metal ink 181 is set for each lot. The expiration date of the lot here refers to, for example, the expiration date for each unit in which the metal ink 181 is sold as a product, and if the metal ink 181 is sold in a tank, it is the expiration date set for each tank. When refilling the metal ink 181, the control device 28 accepts the expiration date of the refilled metal ink 181. The user operates the touch panel 139 to input the expiration date of the tank containing the refilled metal ink 181. For example, when the expiration date passes before the refilled metal ink 181 is used up, the control device 28 starts the process shown in FIG. 6, discharges the metal ink 181, and cleans it with a cleaning liquid 197. 6 when it is predicted before production that the expiration date will pass during production of the circuit board 151. In the present application, the removal of the metal ink 181 from the first and second tanks 171A, 171B for disposal or removal is referred to as "discharge" in order to distinguish it from the operation of ejecting the metal ink 181 for forming the metal wiring 157.

[0062] In addition, when the metal ink 181 is already stored in the first and second tanks 171A, 171B and is to be replenished by topping up, the expiration date of the already stored metal ink 181 may be given priority. For example, when the metal ink 181 is to be replenished after being completely discharged from the first and second tanks 171A, 171B, the control device 28 may accept the expiration date and update the expiration date information, but when the metal ink 181 is to be replenished by topping up, it is not necessary to update the expiration date.

[0063] In addition, the condition for starting the process of FIG. 6 is not limited to the expiration date. For example, the metal ink 181 may dry out under normal temperature and pressure. Therefore, if the time during which the metal wiring 157 is not formed becomes long, the metal ink 181 in the nozzle 209 of the inkjet head 76 may dry out and the silver particles may adhere to the nozzle 209. As a result, ejection failure may occur and the metal wiring 157 may not be formed properly. In turn, the inkjet head 76 may break down and need to be replaced. Therefore, the control device 28 may start the process of FIG. 6 when there is a risk of the metal ink 181 drying out, such as when the metal ink 181 in the tank has not been used for a long time.

[0064] For example, as shown in Fig. 5, assume that the metal ink 181 is stored in the first and second tanks 171A, 171B in an amount between upper limit values ​​TH1A, TH1B and lower limit values ​​TH2A, TH2B, and the current date and time reaches the expiration date of the metal ink 181. As shown in Fig. 6, the control device 28 first discharges (purges) the metal ink 181 to the lower limit value in step (hereinafter simply referred to as S) 1.

[0065] The control device 28 opens both the first solenoid valves 187A, 187B (see FIG. 4) and supplies positive pressure from the positive pressure pump 173 to both the first and second tanks 171A, 171B. The control device 28 also opens both the nozzle solenoid valves 201A, 201B. The fourth solenoid valve 193 is closed. As a result, as shown in FIG. 7, the metal ink 181 in both the first and second tanks 171A, 171B is discharged from the nozzle 209. Therefore, the control device 28 starts and executes the discharge of the metal ink 181 from the first and second tanks 171A, 171B simultaneously. When the metal ink 181 in the first tank 171A reaches the lower limit value TH2A based on the detection signal of the first liquid sensor 213A, the control device 28 closes the first solenoid valve 187A and the nozzle solenoid valve 201A. Similarly, when the metal ink 181 in the second tank 171B reaches the lower limit value TH2B, the control device 28 closes the first solenoid valve 187B and the nozzle solenoid valve 201B.

[0066] As described above, in a state where the metal ink 181 is stored, the first and second tanks 171A and 171B are supplied with the same negative pressure, and the same amount of metal ink 181 is stored. In addition, since the supply of the same positive pressure to the first and second tanks 171A and 171B is started simultaneously during discharge, the metal ink 181 in the first and second tanks 171A and 171B reaches the lower limit values ​​TH2A and TH2B simultaneously. Therefore, the control device 28 can start discharging the two tanks simultaneously and stop the discharging simultaneously based on the detection signals of the first and second liquid sensors 213A and 213B. Note that the control device 28 may separately execute the process of discharging the metal ink 181 from the first tank 171A and the process of discharging the metal ink 181 from the second tank 171B. For example, the control device 28 may execute the discharge of the first tank 171A and then the discharge of the second tank 171B.

[0067] Here, Fig. 10 shows a process for discharging the metal ink 181 of the comparative example. As shown in Fig. 10, when discharging the metal ink 181, if the metal ink 181 is discharged until the first and second tanks 171A and 171B are empty, there is a risk that a foam lump 217 will be generated on the discharge surface of the nozzle 209. This is thought to be because the high viscosity of the metal ink 181 causes droplets of the metal ink 181 to stick to the discharge surface of the nozzle 209, and air discharged from the nozzle 209 by positive pressure enters the droplets, generating the foam lump 217. If the inkjet head 76 moves with the foam lump 217 attached to the nozzle 209, the foam lump 217 may adhere to other units, causing equipment failure or sensor malfunction. Therefore, in this embodiment, the control device 28 does not completely discharge the metal ink 181 in S1, but interrupts the discharge leaving only an amount that corresponds to the lower limit values ​​TH2A, TH2B (an example of a predetermined amount in this application), and then replenishes the cleaning liquid 197 before discharging it.

[0068] As shown in Fig. 8, after leaving the metal ink 181 up to the lower limit values ​​TH2A, TH2B in S1, the control device 28 supplies cleaning liquid 197 to each of the first and second tanks 171A, 171B (S2). After supplying cleaning liquid 197 to the first tank 171A, the control device 28 supplies cleaning liquid 197 to the second tank 171B. Note that Fig. 8 shows a state in which cleaning liquid 197 is being supplied to the first tank 171A.

[0069] In S2, first, the control device 28 closes the nozzle solenoid valve 201A and opens the second solenoid valve 188A to make the first tank 171A negative pressure. The control device 28 also switches the three-way valve 194 to the first tank 171A side and opens the fourth solenoid valve 193 to start supplying the cleaning liquid 197 from the cleaning liquid tank 195 to the first tank 171A. The control device 28 executes control to supply only a preset supply amount of the cleaning liquid 197 to the first tank 171A. Specifically, the control device 28 closes the second solenoid valve 188A to stop the supply when a preset supply time has elapsed from the time when the second solenoid valve 188A is opened and the supply of the cleaning liquid 197 is started. Note that the timing to start measuring the supply time is not limited to the timing to open the second solenoid valve 188A. For example, the measurement of the supply time may start from the timing when the second solenoid valve 188A is opened to start supplying the cleaning liquid 197 and the detection value of the first liquid sensor 213A increases, that is, when the liquid level starts to rise. In addition, in the operation of supplying the cleaning liquid 197 from the cleaning liquid tank 195, the control device 28 may open the nozzle solenoid valves 201A, 201B to create a negative pressure in the tank. In addition, in a configuration in which the first and second cleaning liquid supply ports 191A, 191B are connected to the cleaning liquid tank 195 by separate flow paths, the cleaning liquid 197 may be supplied from the cleaning liquid tank 195 to both the first and second tanks 171A, 171B at the same time.

[0070] As described above, the purpose of supplying the cleaning liquid 197 in S2 is to dilute the metal ink 181 stored in the first and second tanks 171A and 171B, more specifically, to dilute the metal ink 181 to an extent that no foam lumps 217 are generated even if the tanks are emptied after dilution. For this reason, the amount of cleaning liquid 197 supplied in S2 is an amount that can dilute the metal ink 181 to an extent that no foam lumps 217 are generated. The supply time is the time required to supply this amount of cleaning liquid 197 from the cleaning liquid tank 195 to the first tank 171A. As shown in FIG. 8, for example, the height of the liquid level of the mixture of the metal ink 181 and the cleaning liquid 197 after the cleaning liquid 197 is supplied is closer to the lower limit TH2A than the upper limit TH1A. In other words, the supply amount of the cleaning liquid 197 has the following relationship. Supply amount < (upper limit TH1A - lower limit TH2A) / 2 After stopping the supply of cleaning liquid 197 to the first tank 171A, the control device 28 switches the three-way valve 194 to the second tank 171B side, closes the nozzle solenoid valve 201B, opens the fourth solenoid valve 193, and opens the second solenoid valve 188B to create negative pressure in the second tank 171B, and supplies cleaning liquid 197 from the cleaning liquid tank 195 to the second tank 171B for the same supply time as the above-mentioned time. For example, the first and second tanks 171A and 171B are supplied with the same amount of cleaning liquid 197, and the metal ink 181 is diluted to the same concentration.

[0071] Next, in S3, the control device 28 discharges the stored liquid (mixture of the metal ink 181 and the cleaning liquid 197) stored in each of the first and second tanks 171A and 171B until the tanks are empty (see FIG. 9). The control device 28 opens both of the first solenoid valves 187A and 187B, supplies positive pressure from the positive pressure pump 173 to both of the first and second tanks 171A and 171B, and opens both of the nozzle solenoid valves 201A and 201B. For example, the control device 28 opens the nozzle solenoid valves 201A and 201B, and when a preset discharge time has elapsed from the time when the discharge of the stored liquid started, closes the first solenoid valves 187A and 187B and the nozzle solenoid valves 201A and 201B to stop the discharge. This discharge time is the time required to discharge the stored liquid until the first and second tanks 171A and 171B are empty. The timing to start measuring the discharge time is not limited to the timing to open the nozzle solenoid valves 201A and 201B. For example, the measurement of the discharge time may start from the timing when a decrease in the detection value of the first liquid sensor 213A, that is, a decrease in the height of the liquid surface, is detected.

[0072] Although the first and second tanks 171A, 171B are emptied by S3, there is a possibility that metal ink 181 may be attached to the inner walls of the tanks. For this reason, after executing S3, the control device 28 executes cleaning of the first and second tanks 171A, 171B with cleaning liquid 197 (S4). For example, the control device 28 supplies cleaning liquid 197 only to the first tank 171A, and after supplying cleaning liquid 197 up to the upper limit value TH1A, circulates the supplied cleaning liquid 197 between the first and second tanks 171A, 171B and discharges it. This cleaning operation is executed several times to perform cleaning. Thereafter, in order to prevent the cleaned first and second tanks 171A, 171B and the inkjet head 76 from drying, the control device 28, for example, supplies the cleaning liquid 197 to the first tank 171A up to an upper limit value TH1A, and creates a negative pressure in the first and second tanks 171A, 171B to maintain a state in which both tanks and the inkjet head 76 are filled with the cleaning liquid 197. The control device 28 then ends the process shown in Fig. 6. Thereafter, for example, in accordance with the start of production of the circuit board 151, the control device 28 discharges the stored cleaning liquid 197 and supplies the metal ink 181 to the first and second tanks 171A, 171B to form the metal wiring 157.

[0073] As described above, the metal ink 181 in the first and second tanks 171A, 171B is diluted by supplying the cleaning liquid 197 in S2. In other words, the viscosity of the mixture of the metal ink 181 and the cleaning liquid 197 stored in the first and second tanks 171A, 171B after S2 is executed is lower than the viscosity of the metal ink 181. As a result, by diluting the mixture to reduce its viscosity and then discharging it in S3, it is possible to more reliably prevent the formation of bubble lumps 217 on the ejection surface of the nozzle 209.

[0074] Furthermore, in S3, the control device 28 discharges both the metal ink 181 and the cleaning liquid 197 from both the first and second tanks 171A, 171B. This allows the metal ink 181 diluted with the cleaning liquid 197 to be removed from the first and second tanks 171A, 171B. After dilution, the metal ink 181 can be removed with a single discharge operation. This can prevent problems such as the metal ink 181 in the nozzles 209 drying out and silver particles adhering to the nozzles 209.

[0075] Furthermore, in S1, the control device 28 discharges the metal ink 181 up to a position that corresponds to the lower limit values ​​TH2A, TH2B used in the determination of the first and second liquid sensors 213A, 213B. In this way, by using the lower limit values ​​TH2A, TH2B for determining the detection values ​​of the sensors also for discharging the metal ink 181, it is possible to reduce the number of parameters required for the control of the control device 28.

[0076] Moreover, the control device 28 judges whether or not at least one of the first and second conditions is satisfied before starting the production of the circuit board 151 (an example of a lower limit judgment process of the present application). Then, when at least one of the first and second conditions is satisfied, the control device 28 judges that the metal ink 181 needs to be replenished, and notifies the replenishment via the touch panel 139 (an example of a replenishment notification process of the present application). This makes it possible to prevent the occurrence of a situation in which the metal ink 181 runs short during production. In particular, in the three-dimensional additive manufacturing of the circuit board 151, the manufacturing may be performed over a long period of time, such as a day, and the operator is not always in front of the board forming device 10 or the monitoring device during production. For this reason, if possible, it is extremely effective in reducing the operator's workload to judge the amount of the metal ink 181 at the timing when a production start instruction is issued, that is, at the timing when the operator is more surely present, and to prompt the operator to replenish if necessary. Moreover, by using such lower limit values ​​TH2A and TH2B also for controlling the discharge of the metal ink 181, the number of parameters required for control can be reduced.

[0077] In addition, in S2, the control device 28 supplies the cleaning liquid 197 to the first and second tanks 171A, 171B by a preset supply amount. In this way, by managing the supply amount, it is possible to suppress the occurrence of problems such as the mixed liquid after supply exceeding the upper limit values ​​TH1A, TH1B and reaching the first and second cleaning liquid supply ports 191A, 191B and flowing back.

[0078] Furthermore, in S2, the control device 28 supplies the cleaning liquid 197 to the first and second tanks 171A, 171B for a preset supply time, thereby supplying a preset supply amount of the cleaning liquid 197. This allows the amount of the cleaning liquid 197 used in S2 to be adjusted by setting the supply time. In other words, the amount of the cleaning liquid 197 used to dilute the metal ink 181 can be adjusted to an appropriate amount. The appropriate amount here refers to the minimum amount that can dilute the metal ink 181 to such an extent that the foam lumps 217 caused by the discharge of the metal ink 181 described above are not generated. This allows the consumption of the cleaning liquid 197 used for dilution to be reduced, which in turn allows the running costs to be reduced.

[0079] In S2, the control device 28 judges whether the preset supply amount of the cleaning liquid 197 has been supplied by judging the time (supply time), but the supply amount may be judged by a method other than time. For example, in S2, the control device 28 may supply the cleaning liquid 197 until the stored liquid reaches the upper limit values ​​TH1A and TH1B. In this case, the amount supplied until the upper limit values ​​TH1A and TH1B are reached is an example of the preset supply amount of the present application. This allows the upper limit values ​​TH1A and TH1B used for other purposes to be diverted as parameters for judging the supply amount in S2. In addition, the cleaning liquid 197 may not be supplied up to the upper limit values ​​TH1A and TH1B. For example, the cleaning liquid 197 may be supplied up to a position that is a predetermined distance below the upper limit values ​​TH1A and TH1B.

[0080] As described above, the control device 28 judges whether the liquid level of the metal ink 181 in the first tank 171A is equal to or higher than the upper limit value TH1A after the metal ink 181 is refilled or after receiving an instruction to start production (an example of an upper limit value judgment step in the present application). If the liquid level is equal to or higher than the upper limit value TH1A, the control device 28 discharges the metal ink 181 until the liquid level becomes less than the upper limit value TH1A (an example of an excess discharge step in the present application). As described above, when the metal ink 181 is refilled manually, it may be difficult to check the amount of the metal ink 181 in the tank during refilling. For this reason, there is a possibility that the metal ink 181 will be refilled to the upper limit values ​​TH1A and TH1B or higher. If the first printing unit 72 starts operating in this state, there is a risk that the metal ink 181 will splash and adhere to the first and second lenses 215A and 215B. As a result, there is a risk that the first and second liquid sensors 213A and 213B will erroneously detect the liquid level. Furthermore, if too much metal ink 181 is poured into the tank, the head pressure of the tank increases, changing the manner in which the metal ink 181 is discharged from the nozzle 209, which may result in a deterioration in the electrical characteristics of the metal wiring 157 to be formed. Therefore, when the metal ink 181 is equal to or greater than the upper limit values ​​TH1A, TH1B after refilling or before production, the control device 28 discharges the metal ink 181, thereby preventing the occurrence of the above-mentioned problems. Furthermore, by using such upper limit values ​​TH1A, TH1B for controlling the discharge of the metal ink 181, the number of parameters required for control can be reduced. Note that the control device 28 may execute the above-mentioned determination of the upper limit values ​​TH1A, TH1B and discharge process at least one of after the metal ink 181 is refilled and before production is started (e.g., after an instruction to start production is received).

[0081] Furthermore, in S1, the control device 28 simultaneously discharges the metal ink 181 from the first and second tanks 171A, 171B. Furthermore, in S3, the control device 28 simultaneously discharges the metal ink 181 and the cleaning liquid 197 from the first and second tanks 171A, 171B. When discharging from the first and second tanks 171A, 171B in order, it is necessary to switch the first solenoid valves 187A, 187B to switch the tank to be discharged to the second tank 171B after discharging from the first tank 171A is completed. In contrast, by discharging from the two tanks simultaneously, discharging can be performed without switching the first solenoid valves 187A, 187B. The control device 28 may sequentially discharge the stored liquid from the first and second tanks 171A, 171B.

[0082] The inkjet head 76 also includes a second nozzle flow path 207 that connects the first and second tanks 171A and 171B. Each of the first and second tanks 171A and 171B is connected to a plurality of nozzles 209 via the second nozzle flow path 207, and is also connected to each other via the second nozzle flow path 207. This allows the flow path that connects the first and second tanks 171A and 171B to each other and the flow path that connects each tank to the nozzle 209 to be a common flow path as the second nozzle flow path 207. This allows the number of flow paths required for the inkjet head 76 to be reduced. In addition, it is possible to simultaneously discharge the stored liquids in the two tanks from the same nozzle 209. The inkjet head 76 may also be configured to include a nozzle 209 for the first tank 171A and a nozzle 209 for the second tank 171B separately.

[0083] Incidentally, in the above embodiment, the substrate forming apparatus 10 is an example of a modeling apparatus. The first printing unit 72 is an example of an ejection device of the present application. The metal ink 181 is an example of a metal-containing liquid. The first and second tanks 171A, 171B are an example of a tank. The second nozzle flow path 207 is an example of a flow path. The first liquid sensor 213A and the second liquid sensor 213B are an example of a liquid sensor. The process of S1 is an example of a discharge interruption process or a discharge interruption process. The process of S2 is an example of a cleaning liquid supply process or a cleaning liquid supply process. The process of S3 is an example of a discharge process or a discharge process.

[0084] As described above, the above embodiment provides the following advantages. In one aspect of the present embodiment, the control device 28 stops discharging in S1 while the metal ink 181 of the lower limit values ​​TH2A and TH2B remains. This makes it possible to prevent the droplets of the metal ink 181 from sticking to the ejection surface of the nozzle 209 and to prevent air from entering the droplets by interrupting the ejection. Then, the control device 28 supplies the cleaning liquid 197 to the first and second tanks 171A and 171B (S2), and then discharges the metal ink 181 remaining in the first and second tanks 171A and 171B from the nozzle 209 together with the cleaning liquid 197 (S3). This makes it possible to discharge the metal ink 181 while it is in a high concentration and high viscosity state, without discharging it until the tank becomes empty, and after lowering the viscosity of the metal ink 181. This makes it possible to prevent the droplets from sticking to the ejection surface of the nozzle 209, the air from entering, and the bubble lump 217 from being generated. As a result, it is possible to prevent the bubbles from adhering to other units, and to prevent the occurrence of device failures.

[0085] The present disclosure is not limited to the above-described embodiments, but can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. 6 are merely examples. For example, in the process of S3, the control device 28 may discharge the metal ink 181 and the cleaning liquid 197 from the two tanks in sequence rather than simultaneously. Alternatively, the stored liquid may not be discharged all at once, but may be discharged in multiple batches. Also, in S2, the cleaning liquid 197 may be supplied to a position above the upper limit values ​​TH1A, TH1B and below the first and second cleaning liquid supply ports 191A, 191B.

[0086] Moreover, the shape of circuit board 151, electronic components 163, the number of metal wirings 157, and the like shown in FIG. 3 are merely examples. The first printing unit 72 may also include three or more tanks (such as the first and second tanks 171A and 171B) for storing the metal ink 181. The first printing unit 72 may also discharge and circulate the metal ink 181 and the cleaning liquid 197 in the three or more tanks. Alternatively, the first printing unit 72 may be configured to include only one tank for storing the metal ink 181. FIG. 11 shows the configuration of a first printing unit 72A of another example. As shown in FIG. 11, the first printing unit 72A of another example includes only the first tank 171A, and includes only the configuration related to the first tank 171A with respect to the first liquid sensor 213A, the first solenoid valve 187A (see FIG. 4), and the like. In this case, in discharging the metal ink 181, the control device 28 may execute, for example, a process (S1) of interrupting the discharge of the metal ink 181, a process (S2) of supplying the cleaning liquid 197, and a process (S3) of discharging the mixed liquid, as in the case of FIG. 7 to FIG. 9. Even in such a configuration including only one tank, it is possible to suppress the generation of the foam lump 217 by diluting the metal ink 181 before discharging it.

[0087] Furthermore, although board forming apparatus 10 includes mounting unit 27 and is configured to perform the process up to mounting electronic component 163, board forming apparatus 10 does not need to include mounting unit 27. In this case, board forming apparatus 10 may perform the production up to the circuit board before mounting electronic component 163. In addition, the first solenoid valves 187A, 187B, the second solenoid valves 188A, 188B, the third solenoid valves 189A, 189B, the fourth solenoid valve 193, the three-way valve 194, and the nozzle solenoid valves 201A, 201B that switch the flow paths are not limited to solenoid valves (solenoid valves), and may be, for example, valves that are driven by a motor or piezo valves that use piezoelectric elements. Also, pneumatic or hydraulic valves may be used. Furthermore, although the first printing unit 72 ejects the metal ink 181 from both the first and second tanks 171A, 171B, it may be configured to eject the metal ink 181 from only one of them. For example, if the first printing unit 72 is configured to eject the metal ink 181 only from the first tank 171A, the nozzle solenoid valve 201B is closed and the nozzle solenoid valve 201A is opened when ejecting the metal ink 181, and the first tank 171A is put under negative pressure. Furthermore, when the amount of ink in the first tank 171A is decreasing, the control device 28 may open the nozzle solenoid valves 201A, 201B to replenish the metal ink 181 from the second tank 171B to the first tank 171A. The positive pressure pump 173 and the negative pressure pump 174 may be a single device. That is, the first printing unit 72 may be provided with a pump that can supply both positive pressure and negative pressure. Furthermore, the first printing unit 72 may not be provided with the first and second liquid sensors 213A, 213B. In addition, in the above-described embodiment, the metal ink 181 is used as the metal-containing liquid of the present application, but other metal-containing liquids such as a conductive paste discharged by the dispenser 106 may be used. Therefore, the discharge device of the present application is not limited to a configuration including an inkjet head, and may be a configuration including a dispenser (such as an air dispenser or a jet dispenser).

[0088] The contents of the present disclosure are not limited to the dependent relationships described in the claims. For example, this specification also discloses the technical idea of ​​changing "the discharge method according to claim 1 or claim 2" in claim 4 to "the discharge method according to any one of claims 1 to 3". For example, this specification also discloses the technical idea of ​​changing "the discharge method according to claim 1 or claim 2" in claim 6 to "the discharge method according to any one of claims 1 to 5". For example, this specification also discloses the technical idea of ​​changing "the discharge method according to claim 1 or claim 2" in claim 8 to "the discharge method according to any one of claims 1 to 7". For example, this specification also discloses the technical idea of ​​changing "the discharge method according to claim 1 or claim 2" in claim 10 to "the discharge method according to any one of claims 1 to 9". [Explanation of symbols]

[0089] 10 substrate forming apparatus (molding apparatus), 28 control apparatus, 72, 72A first printing unit (ejection apparatus), 157 metal wiring, 171A first tank (tank), 171B second tank (tank), 181 metal ink (metal-containing liquid), 197 cleaning liquid, 207 second nozzle flow path (flow path), 209 nozzle, 213A first liquid sensor (liquid sensor), 213B second liquid sensor (liquid sensor), TH1A, TH1B upper limit value, TH2A, TH2B lower limit value.

Claims

1. At least one tank capable of storing a metal-containing liquid containing metal fine particles; a nozzle connected to the tank and configured to eject the metal-containing liquid supplied from the tank; A method for discharging the metal-containing liquid from the tank in a discharge device comprising: a discharge interruption step of stopping the discharge when discharging the metal-containing liquid stored in the tank through the nozzle while leaving a predetermined amount of the metal-containing liquid in the tank; a cleaning liquid supplying step of supplying a cleaning liquid to the tank after the discharge interruption step is performed; a discharge step of discharging the metal-containing liquid remaining in the tank together with the cleaning liquid from the nozzle after the cleaning liquid supply step is performed; The discharge method includes:

2. In the discharging step, The method of claim 1 , wherein both the metal-containing liquid and the cleaning liquid are completely drained from the tank.

3. The viscosity of the mixture of the metal-containing liquid and the cleaning liquid stored in the tank after the cleaning liquid supply step is performed is The method according to claim 1 or 2, wherein the viscosity of the metal-containing liquid is lower than that of the metal-containing liquid.

4. The discharge device includes: a liquid sensor that outputs a detection signal corresponding to the amount of liquid stored in the tank; The liquid sensor includes: is used to determine whether the amount of liquid stored in the tank is equal to or less than a predetermined lower limit; The predetermined amount in the discharge interruption step is The discharge method according to claim 1 or 2, wherein the lower limit value is determined by the liquid sensor.

5. a metal wiring forming step of discharging the metal-containing liquid from the nozzle and curing the discharged metal-containing liquid to form a metal wiring; a lower limit value determination step of determining whether or not the metal-containing liquid stored in the tank is equal to or lower than the lower limit value using the liquid sensor before starting the metal wiring forming step; a refill notification step of notifying the tank that the metal-containing liquid needs to be replenished with the metal-containing liquid when the metal-containing liquid is determined to be equal to or lower than the lower limit value by the lower limit value determination step; The method of claim 4 further comprising:

6. In the cleaning liquid supplying step, 3. The method according to claim 1, further comprising the step of supplying the cleaning liquid to the tank in a preset amount.

7. In the cleaning liquid supplying step, The method according to claim 6 , further comprising the step of supplying the cleaning liquid to the tank for a preset supply time, thereby supplying the cleaning liquid to the tank in the supply amount.

8. The discharge device includes: a liquid sensor that outputs a detection signal corresponding to the amount of liquid stored in the tank; The liquid sensor includes: is used to determine whether the amount of liquid stored in the tank is equal to or greater than a predetermined upper limit; The total amount of the metal-containing liquid and the cleaning liquid remaining in the tank after the cleaning liquid supply step is performed is The method according to claim 1 or 2, wherein the concentration is equal to or less than the upper limit value.

9. a metal wiring forming step of discharging the metal-containing liquid from the nozzle and curing the discharged metal-containing liquid to form a metal wiring; an upper limit value determination step of determining whether the metal-containing liquid stored in the tank is equal to or greater than the upper limit value using the liquid sensor at least one of after the metal-containing liquid is replenished in the tank and before the metal wiring forming step is started; an excess discharge step of discharging the metal-containing liquid until the amount of the metal-containing liquid stored in the tank becomes less than the upper limit value when the upper limit value determination step determines that the metal-containing liquid is equal to or greater than the upper limit value; The method of claim 8 further comprising:

10. The discharge device includes: A plurality of the tanks are provided, The discharge method includes: In the discharge interruption step, Discharging the metal-containing liquid from a plurality of the tanks simultaneously; In the discharging step, The discharge method according to claim 1 or 2, wherein the metal-containing liquid and the cleaning liquid are discharged simultaneously from a plurality of the tanks.

11. A discharge device; A control device for controlling the discharge device; Equipped with The discharge device includes: At least one tank capable of storing a metal-containing liquid containing metal fine particles; a nozzle connected to the tank and configured to eject the metal-containing liquid supplied from the tank; Equipped with The control device includes: a discharge interruption process for stopping the discharge when discharging the metal-containing liquid stored in the tank through the nozzle while leaving a predetermined amount of the metal-containing liquid in the tank; a cleaning liquid supply process for supplying a cleaning liquid to the tank after the discharge interruption process is performed; a discharge process of discharging the metal-containing liquid remaining in the tank together with the cleaning liquid from the nozzle after the cleaning liquid supply process has been performed; A molding device that performs the above.

12. A flow path is provided connecting a plurality of the nozzles, A plurality of the tanks are provided, Each of the plurality of tanks comprises: The molding apparatus according to claim 11 , wherein the nozzles are connected to each other via the flow paths.

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