Method for forming an electrical circuit, and control program

Abstract

To appropriately form a circuit board that includes a resin layer that is formed from a curable resin discharged by a discharge device and wiring that is formed on the resin layer.SOLUTION: There is provided an electric circuit formation method that includes: a smooth resin layer formation step in which a smooth resin layer is formed by relatively moving a discharge device and a stage in accordance with a first image and discharging a curable resin onto the stage in a thin-film form; a wiring formation step in which a metal wiring is formed on the smooth resin layer; and a flattened resin layer formation step in which, after discharging the curable resin on the smooth resin layer in the thin-film form by relatively moving the discharge device and the stage in accordance with a second image, the discharge device and the stage are relatively moved in accordance with a third image so as to flatten the surface of the curable resin having been discharged in the thin-film form, thereby forming a flattened resin layer. The number of times the discharge device and the stage are relatively moved in accordance with the third image is greater than the number of times the discharge device and the stage are relatively moved in accordance with the second image.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a circuit forming method and the like for forming metal wiring on a resin layer formed of a curable resin.

Background Art

[0002] The following patent document describes a technology for forming a resin layer with a curable resin discharged by a discharge device.

Prior Art Literature

Patent Literature

[0003]

Patent Literature 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] An object of the present invention is to appropriately form a circuit board including a resin layer formed of a curable resin discharged by a discharge device and wiring formed on the resin layer.

Means for Solving the Problem

[0005] In order to solve the above problem, the present specification provides: a smooth resin layer forming step of forming a smooth resin layer by relatively moving a discharge device that discharges a curable resin and a stage according to a first image and discharging the curable resin in a thin film shape onto the stage; a wiring forming step of forming metal wiring on the smooth resin layer; relatively moving the discharge device and the stage according to a second image to discharge the curable resin in a thin film shape onto the smooth resin layer, The surface of the curable resin is cured without being flattened. after that, relatively moving the discharge device and the stage according to a third image to form a thin film Curable resin discharge and, flattening a surface of the curable resin with a flattening device Then it hardens.The present invention discloses an electrical circuit formation method that includes a flattening resin layer forming step, wherein the number of relative movements between the discharge device and the stage according to the third image is greater than the number of relative movements between the discharge device and the stage according to the second image.

[0006] Furthermore, this specification describes a smooth resin layer forming step in which a curable resin is discharged in a thin film form onto the stage by relatively moving a discharge device and a stage according to a first image, a wiring forming step in which metal wiring is formed on the smooth resin layer, and a process in which a curable resin is discharged in a thin film form onto the smooth resin layer by relatively moving the discharge device and the stage according to a second image. The surface of the curable resin is cured without being flattened. Afterward, the ejection device and the stage are moved relative to each other according to the third image to form a thin film. Curable resin Discharge and, The surface of the curable resin is flattened using a flattening device. Then it hardens. The present invention discloses a control program that controls the operation of a moving device that moves the discharge device and the stage relatively, performing a planar resin layer forming step by which a planar resin layer is formed, such that the number of relative movements between the discharge device and the stage according to the third image is greater than the number of relative movements between the discharge device and the stage according to the second image. [Effects of the Invention]

[0007] In this disclosure, the number of relative movements between the dispensing device and the stage when the curable resin is dispensed in a thin film by moving the dispensing device and the stage relatively according to a third image is greater than the number of relative movements between the dispensing device and the stage when the curable resin is dispensed in a thin film by moving the dispensing device and the stage relatively according to a second image. As a result, the thickness dimension of the curable resin formed according to the third image and the second image This makes it possible to reduce the difference in thickness between the formed curable resin and the actual curing resin, allowing for the proper formation of the circuit board. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing a circuit forming apparatus. [Figure 2] Control device branch. [Figure 3] This is a cross-sectional view showing the circuit with a smooth resin layer formed on it. [Figure 4] This is a cross-sectional view showing a circuit with wiring formed on a smooth resin layer. [Figure 5] This is a cross-sectional view showing a circuit in which a planarized resin layer has been formed on top of a smooth resin layer. [Figure 6] This is a cross-sectional view showing a circuit in which two planar resin layers are formed on top of a smooth resin layer. [Figure 7] This is a cross-sectional view showing a circuit in which three planar resin layers are formed on top of a smooth resin layer. [Figure 8] This figure shows a smooth resin layer formed by a conventional method and three flattened resin layers. [Figure 9] This figure shows a smooth resin layer and three planarized resin layers formed by the method of the present invention. [Figure 10] This is a diagram showing a modified circuit board. [Modes for carrying out the invention]

[0009] Figure 1 shows a circuit forming apparatus 10. The circuit forming apparatus 10 comprises a transport device 20, a first molding unit 22, a second molding unit 24, and a control device (see Figure 2) 28. The transport device 20, the first molding unit 22, and the second molding unit 24 are arranged on a base 29 of the circuit forming apparatus 10. The base 29 is generally rectangular in shape, and in the following description, 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 as the Z-axis direction. Note that the Z-axis direction is the same direction as the vertical direction.

[0010] The transport device 20 comprises 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 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 has an electromagnetic motor (see Figure 2) 38, and the X-axis slider 36 moves to any position in the X-axis direction by the drive of the electromagnetic motor 38. The Y-axis slide mechanism 32 includes a Y-axis slide rail 50 and a table 52. The Y-axis slide rail 50 is mounted on a base 29 so as to extend in the Y-axis direction and is movable in the X-axis direction. One end of the Y-axis slide rail 50 is connected to the X-axis slider 36. The table 52 is held on the Y-axis slide rail 50 so as to be slidable in the Y-axis direction. Furthermore, the Y-axis sliding mechanism 32 has an electromagnetic motor (see Figure 2) 56, and the table 52 moves to any position in the Y-axis direction when driven by the electromagnetic motor 56. As a result, the table 52 moves to any position on the base 29 when driven by the X-axis sliding mechanism 30 and the Y-axis sliding mechanism 32.

[0011] The table 52 comprises a base 60, a holding device 62, and a lifting device (see Figure 2) 64. The base 60 is formed in a flat shape, and a pallet (see Figure 3) 70 is placed on its upper surface. The holding devices 62 are provided on both sides of the base 60 in the X-axis direction. The pallet 70 is held in place by being sandwiched between the holding devices 62 at both edges in the X-axis direction. The lifting device 64 is located below the base 60 and raises and lowers the base 60.

[0012] The first modeling unit 22 is a unit that models wiring on a circuit board, and includes a first printing section 72 and a firing section 74. The first printing section 72 includes an inkjet head (see FIG. 2) 76, and the inkjet head 76 ejects metallic ink in a linear shape. The metallic ink is formed by dispersing nanometer-sized metal, for example, fine silver particles, in a solvent. The surface of the fine metal particles is coated with a dispersant to prevent aggregation in the solvent. Further, the inkjet head 76 ejects metallic ink from a plurality of nozzles, for example, by a piezo method using a piezoelectric element.

[0013] The firing section 74 includes an infrared irradiation device (see FIG. 2) 78. The infrared irradiation device 78 is a device that irradiates infrared rays onto the ejected metallic ink, and the metallic ink irradiated with infrared rays is fired to form wiring. Note that firing of metallic ink refers to a phenomenon in which energy application causes vaporization of the solvent, decomposition of the protective film of the fine metal particles, that is, the dispersant, etc., and the fine metal particles come into contact or fuse with each other, resulting in increased electrical conductivity. Then, metallic wiring is formed by firing the metallic ink.

[0014] Further, the second modeling unit 24 is a unit that models a resin layer of a circuit board, and includes a second printing section 84 and a curing section 86. The second printing section 84 includes an inkjet head (see FIG. 2) 88, and the inkjet head 88 ejects an ultraviolet curable resin. The ultraviolet curable resin is a resin that cures when irradiated with ultraviolet rays. Note that the inkjet head 88 may employ, for example, a piezo method using a piezoelectric element, or a thermal method in which the resin is heated to generate bubbles and ejected from a plurality of nozzles.

[0015] The curing unit 86 includes a planarization device (see FIG. 2) 90 and an irradiation device (see FIG. 2) 92. The planarization device 90 planarizes the top surface of the ultraviolet curable resin discharged by the inkjet head 88. For example, the planarization device 90 uniformizes the thickness of the ultraviolet curable resin by scraping off excess resin with a roller or a blade while leveling the surface of the ultraviolet curable resin. Further, the irradiation device 92 includes a mercury lamp or an LED as a light source, and irradiates the discharged ultraviolet curable resin with ultraviolet rays. Thereby, the discharged ultraviolet curable resin is cured to form a resin layer.

[0016] Further, as shown in FIG. 2, the control device 28 includes a controller 110 and a plurality of drive circuits 112. The plurality of drive circuits 112 are connected to the electromagnetic motors 38 and 56, the holding device 62, the lifting device 64, the inkjet head 76, the infrared irradiation device 78, the inkjet head 88, the planarization device 90, and the irradiation device 92. The controller 110 includes a CPU, a ROM, a RAM and the like, is mainly composed of a computer, and is connected to the plurality of drive circuits 112. Further, a control program 118 is stored in the controller 110, and the operations of the conveyance device 20, the first modeling unit 22, and the second modeling unit 24 are controlled in accordance with the control program 118.

[0017] In the circuit forming apparatus 10, with the configuration described above, a smooth resin layer is formed on the pallet 70 placed on the base 60 of the table 52, a wiring is formed on the smooth resin layer, and further a planarized resin layer is formed on the smooth resin layer, thereby forming a circuit board.

[0018] Specifically, when the pallet 70 is set on the base 60 of the table 52, the table 52 moves to below the second modeling unit 24. Then, in the second modeling unit 24, as shown in FIG. 3, the smooth resin layer 120 is formed on the pallet 70. The smooth resin layer 120 is formed by the inkjet head 88 discharging the ultraviolet curable resin while reciprocating above the pallet 70, and the irradiation device 92 curing the ultraviolet curable resin.

[0019] More specifically, in the second printing section 84 of the second molding unit 24, the inkjet head 88 ejects UV-curable resin according to the first resin layer image data while moving above the pallet 70 in a predetermined direction. Then, the inkjet head 88 ejects UV-curable resin according to the first resin layer image data while moving above the pallet 70 in the opposite direction to the predetermined direction. In other words, the inkjet head 88 ejects UV-curable resin according to the first resin layer image data while moving back and forth above the pallet 70. Note that ejecting UV-curable resin while the inkjet head 88 moves in one direction is referred to as ejecting UV-curable resin in one pass. In other words, when the inkjet head 88 ejects UV-curable resin while moving back and forth once above the pallet 70, the inkjet head 88 ejects UV-curable resin in two passes. When the inkjet head 88 ejects UV-curable resin in 32 passes, the irradiation device 92 in the curing section 86 irradiates the UV-curable resin with UV light. As a result, a smooth resin layer 120 with a thickness of approximately 66 μm is formed on the pallet 70. During the formation of the smooth resin layer 120, as described above, the inkjet head 88 ejects the UV-curable resin in multiple passes, and then UV light is irradiated onto the UV-curable resin. In other words, the smooth resin layer 120 is formed by the irradiation of UV light onto the layered UV-curable resin. Therefore, due to the surface tension of the layered UV-curable resin, the surface of the smooth resin layer 120 becomes an extremely smooth surface with very few fine irregularities.

[0020] Next, once the smooth resin layer 120 is formed, the table 52 moves below the first molding unit 22. Then, in the first printing section 72 of the first molding unit 22, the inkjet head 76 ejects metallic ink 122 in a linear pattern onto the upper surface of the smooth resin layer 120, as shown in Figure 4. Subsequently, the infrared irradiation device 78 in the firing section 74 of the first molding unit 22 irradiates the ejected metallic ink 122 with infrared light. This causes the metallic ink 122 to be fired, and wiring 124 is formed on the upper surface of the smooth resin layer 120. In this way, by forming wiring 124 on the surface of the smooth resin layer 120, which has very few fine irregularities, the resistance value of the wiring can be reduced. On the other hand, although the surface of the smooth resin layer 120 is smooth, when the ultraviolet curing resin is applied in layers, the ultraviolet curing resin gathers at the edges of the applied ultraviolet curing resin due to surface tension, and as a result, a smooth resin layer 120 is formed where the thickness dimension of the edges is thicker than the thickness dimension of the central part. In other words, a smooth resin layer 120 with different thickness dimensions is formed in each part. Therefore, in order to cancel out the difference in thickness dimensions of the smooth resin layer 120 in each part, a flattened resin layer is formed on top of the smooth resin layer 120. Note that the difference in thickness dimensions of the smooth resin layer 120, that is, the difference in thickness dimensions between the edges and the center of the smooth resin layer 120, may be 100 μm or more.

[0021] More specifically, when the wiring 124 is formed on the smooth resin layer 120, the table 52 moves below the second molding unit 24. Then, in the second printing section 84 of the second molding unit 24, the inkjet head 88 moves above the smooth resin layer 120 and ejects ultraviolet-curable resin according to the second resin layer image data. At this time, when the inkjet head 88 ejects the ultraviolet-curable resin onto the smooth resin layer 120 in one pass, the irradiation device 92 in the curing section 86 irradiates the ultraviolet-curable resin with ultraviolet light. In other words, ultraviolet light is irradiated onto the ultraviolet-curable resin ejected in one pass. As a result, the ultraviolet-curable resin ejected in one pass is cured. Subsequently, the inkjet head 88 ejects ultraviolet-curable resin onto the smooth resin layer 120 in one pass according to the second resin layer image data, and the irradiation device 92 irradiates the ultraviolet-curable resin with ultraviolet light. Then, as shown in Figure 5, a planar resin layer 130 is formed on the smooth resin layer 120 by repeating the process of ejecting UV-curable resin with one pass and irradiating the UV-curable resin ejected with one pass 32 times. The planar resin layer 130 is formed by repeating the process of ejecting UV-curable resin with one pass and irradiating the UV-curable resin ejected with one pass 32 times. In other words, the inkjet head 88 ejects UV-curable resin with 32 passes, The irradiation device 92 irradiates the UV-curing resin with ultraviolet light after each of the two passes, thereby forming a planarized resin layer 130. As a result, a planarized resin layer 130 with a thickness of approximately 66 μm is formed on top of the smooth resin layer 120. The wiring 124 formed on top of the smooth resin layer 120 is embedded between the smooth resin layer 120 and the planarized resin layer 130, and is therefore shown with a dotted line.

[0022] Furthermore, the thickness dimension of the flattened resin layer 130 is approximately 66 μm, and the difference in thickness dimension of the smooth resin layer 120 located below the flattened resin layer 130 can be 100 μm or more, as mentioned above. For this reason, if the surface of the UV-curable resin is flattened by the flattening device 90 when forming the flattened resin layer 130, there is a risk that the flattening device 90 will interfere with the smooth resin layer 120. For this reason, the surface of the flattened resin layer 130 is not flattened when forming the flattened resin layer 130. However, when forming the flattened resin layer 130, UV light is irradiated each time the UV-curable resin is extruded in one pass, so the amount of UV-curable resin that moves to the edges due to surface tension in the extruded UV-curable resin is extremely small. For this reason, the difference in thickness dimension from part to part in the flattened resin layer 130 is minute, and the flattened resin layer 130 becomes a flat resin layer.

[0023] Then, when the planar resin layer 130 is formed on the smooth resin layer 120, a planar resin layer 140 is formed on top of the planar resin layer 130, as shown in Figure 6. The planar resin layer 140 is formed by the same method as the planar resin layer 130. That is, the inkjet head 88 ejects UV-curable resin onto the planar resin layer 130 in 32 passes, and the irradiation device 92 irradiates the UV-curable resin with UV light after each of the 32 passes, thereby forming the planar resin layer 140 on top of the planar resin layer 130. As a result, a planar resin layer 140 with a thickness of approximately 66 μm is formed on top of the planar resin layer 130. However, when the planar resin layer 130 is formed, the inkjet head 88 ejects UV-curable resin according to the second resin layer image data, but when the planar resin layer 140 is formed, the inkjet head 88 ejects UV-curable resin according to the third resin layer image data.

[0024] The combined thickness of the flattened resin layer 130 and the flattened resin layer 140 is approximately 132 μm, and the difference in thickness of the smooth resin layer 120 can be 100 μm or more. Therefore, when forming the flattened resin layer 140, if the surface of the UV-curing resin is flattened by the flattening device 90, the flattening device 90 may interfere with the smooth resin layer 120. For this reason, the surface of the flattened resin layer 140 is not flattened when forming the flattened resin layer 140. However, since the flattened resin layer 140 is formed by the same method as the flattened resin layer 130, the flattened resin layer 140 is also a flat resin layer.

[0025] Then, when the planar resin layer 140 is formed on top of the planar resin layer 130, as shown in Figure 7, the planar resin layer 150 is formed on top of the planar resin layer 140. The planar resin layer 150 is also formed using the same method as the planar resin layers 130 and 140. In other words, ultraviolet light is irradiated each time the ultraviolet curing resin is ejected in one pass. However, when the planar resin layer 150 is formed, the inkjet head 88 ejects the ultraviolet curing resin according to the fourth resin layer image data. Also, the planarization device 90 moves horizontally at a height of approximately 154 μm from the top surface of the smooth resin layer 120. Therefore, when the thickness dimension of the planar resin layer 150 becomes approximately 22 μm (=154-66-66), when the inkjet head 88 ejects the ultraviolet curing resin in one pass, the ejected ultraviolet curing resin is scraped off by the planarization device 90, and the planar resin layer 150 is planarized. In this process, the flattening resin layer 150 is pressed downwards, and the smooth resin layer 120 is also pressed downwards via the flattening resin layers 130 and 140, canceling out the differences in thickness dimensions between parts of the smooth resin layer 120. Furthermore, the flattening device 90 moves back and forth many times at a height of approximately 154 μm from the top surface of the smooth resin layer 120, and when the flattening resin layer 150 is formed, the inkjet head 88 ejects the UV-curing resin in 32 passes. In other words, by ejecting the UV-curing resin in 32 passes, approximately 66 While it is possible to form a resin layer with a thickness of μm, if the thickness of the flattened resin layer 150 becomes approximately 22 μm, the UV-curable resin ejected each time it is ejected is scraped off by the flattening device 90. Furthermore, considering that ejecting UV-curable resin in 32 passes forms a resin layer with a thickness of approximately 66 μm, ejecting UV-curable resin in one pass forms a resin layer with a thickness of approximately 2 μm (≒66 / 32). In other words, when UV-curable resin is ejected in approximately 11 passes, the thickness of the flattened resin layer 150 becomes approximately 22 μm. Therefore, when the inkjet head 88 ejects UV-curable resin in 32 passes, the UV-curable resin ejected in each of approximately 21 passes (=32-11) is scraped off by the flattening device 90. In other words, the surface of the flattening resin layer 150 is flattened 21 times by the flattening device 90, and the flattening resin layer 150 is pressed downwards 21 times, so the smooth resin layer 120 is also pressed downwards 21 times via the flattening resin layers 130 and 140. This makes it possible to appropriately cancel out differences in the thickness dimensions of different parts of the smooth resin layer 120. In this way, with the flattening device 90 moving back and forth many times at a predetermined height, the inkjet head 88 ejects ultraviolet-curable resin in 32 passes, and the irradiation device 92 irradiates with ultraviolet light after each of the 32 passes, thereby forming a flattening resin layer 150 with a thickness of approximately 22 μm.

[0026] However, if the smooth resin layer 120 and the planarized resin layers 130, 140, and 150 are formed using the method described above, the thickness dimensions of the smooth resin layer 120 and the planarized resin layers 130, 140, and 150 will differ significantly, which may cause the shape of the printed circuit board to be distorted, and the shape of the actually formed circuit board may deviate significantly from the design model. Specifically, as shown in Figure 8, in the smooth resin layer 120, the inkjet head 88 ejects ultraviolet-curable resin in 32 passes according to the first resin layer image data, forming a smooth resin layer 120 with a thickness of 66 μm. Similarly, in the planarized resin layer 130, the inkjet head 88 ejects ultraviolet-curable resin in 32 passes according to the second resin layer image data, forming a planarized resin layer 130 with a thickness of 66 μm. Furthermore, in the planarized resin layer 140, the inkjet head 88 ejects UV-curable resin in 32 passes according to the third resin layer image data, forming a planarized resin layer 140 with a thickness of 66 μm. On the other hand, in the planarized resin layer 150 and the planarized resin layer 130, the inkjet head 88 ejects UV-curable resin in 32 passes according to the fourth resin layer image data, but the surface of the planarized resin layer 150 is planarized by the planarization device, forming a planarized resin layer 150 with a thickness of 22 μm. Thus, in the method described above, that is, the conventional method, the thickness of the smooth resin layer 120, the planarized resin layers 130 and 140 are each 66 μm, and the thickness of the planarized resin layer 150 is 22 μm, so the thickness of the resin layers varies between 22 and 66 μm. In other words, the difference between the maximum and minimum thickness of the resin layers is 44 μm (= 66 - 22). Thus, in conventional methods, when UV-curable resin is extruded according to the image data of the first to fourth resin layers, if the UV-curable resin is extruded with the same number of passes (32 passes) for each image data to form each resin layer, the thickness dimensions of each resin layer will differ significantly.

[0027] In light of these considerations, in the circuit formation apparatus 10, the number of passes for the planarized resin layer that is planarized by the planarization apparatus is greater than the number of passes for the planarized resin layer that is not planarized by the planarization apparatus 90. In other words, the number of passes used to form the planarized resin layer 150 according to the fourth resin layer image data is greater than the number of passes used to form the planarized resin layers 130 and 140 according to the second or third resin layer image data. Specifically, as shown in Figure 9, the smooth resin layer 120 is formed in the same manner as in conventional methods, taking into consideration that it is the base on which the wiring 124 is formed. That is, the smooth resin layer 120 is formed when the inkjet head 88 ejects ultraviolet-curable resin in 32 passes according to the first resin layer image data. Therefore, a smooth resin layer 120 with a thickness of 66 μm is formed, similar to conventional methods.

[0028] Next, a planar resin layer 160 is formed on the smooth resin layer 120. However, since the planar resin layer 160 is not planarized by the planarization device 90, the number of passes used to form the planar resin layer 160 is reduced from the conventional number of passes in order to bring the thickness of the planar resin layer 160 closer to the thickness of the resin layer that is planarized by the planarization device 90. Specifically, the number of passes used to form the planar resin layer 160 is reduced by 7 passes from the conventional number of passes (32) to 25 passes. In other words, the inkjet head 88 ejects ultraviolet-curable resin onto the smooth resin layer 120 in 25 passes according to the second resin layer image data, and the irradiation device 92 irradiates the ultraviolet-curable resin with ultraviolet light after each of the 25 passes, thereby forming the planar resin layer 160 on the smooth resin layer 120. As a result, a planar resin layer 160 with a thickness of 51 μm is formed on the smooth resin layer 120.

[0029] Next, a planar resin layer 170 is formed on top of the planar resin layer 160, but this planar resin layer 170 is also formed using the same method as the planar resin layer 160. That is, the inkjet head 88 ejects ultraviolet-curable resin onto the planar resin layer 160 in 25 passes according to the third resin layer image data, and the irradiation device 92 irradiates the ultraviolet-curable resin with ultraviolet light after each of the 25 passes, thereby forming the planar resin layer 170 on top of the planar resin layer 160. As a result, a planar resin layer 170 with a thickness of 51 μm is formed on top of the planar resin layer 160.

[0030] Then, a flattening resin layer 180 is formed on top of the flattening resin layer 170, and this flattening resin layer 180 is flattened by the flattening device 90. For this reason, in order to bring the thickness dimension of the flattening resin layer 180 closer to the thickness dimension of the flattening resin layers 160 and 170 that are not flattened by the flattening device 90, the number of passes during the formation of the flattening resin layer 180 is increased compared to the conventional number of passes. Specifically, the number of passes during the formation of the flattening resin layer 160 is increased by 14 from the conventional number of passes 32, by the sum of the 7 passes that were reduced during the formation of the flattening resin layer 160 and the 7 passes that were reduced during the formation of the flattening resin layer 170, resulting in 46 passes. Then, with the planarization device 90 moving back and forth at a height of approximately 154 μm above the upper surface of the smooth resin layer 120, the inkjet head 88 ejects UV-curable resin in 46 passes according to the image data of the fourth resin layer, and the irradiation device 92 irradiates with UV light after each of the 46 passes, thereby forming the planarized resin layer 180. At this time, when the thickness dimension of the planarized resin layer 180 becomes 51 μm (≒154-51-51), the inkjet head 88 ejects UV-curable resin in one pass, the ejected UV-curable resin is scraped off by the planarization device 90, and the planarized resin layer 180 is planarized. As a result, a planarized resin layer 180 with a thickness dimension of 51 μm is formed on top of the planarized resin layer 170. Furthermore, when the discharged ultraviolet-curing resin is scraped off by the flattening device 90 and the flattened resin layer 180 is flattened, the flattened resin layer 180 is pressed downward, and the smooth resin layer 120 is also pressed downward via the flattened resin layers 160 and 170, thereby canceling out the differences in thickness dimensions of the smooth resin layer 120 in different parts.

[0031] In this way, by reducing the number of passes during the formation of the planarized resin layers 160 and 170 compared to the conventional number of passes, and increasing the number of passes during the formation of the planarized resin layer 180 compared to the conventional number of passes, the number of passes during the formation of the planarized resin layer 180 becomes greater than the number of passes during the formation of the planarized resin layers 160 and 170. This makes it possible to make the thickness dimension (51 μm) of the planarized resin layers 160 and 170 that have not been planarized by the planarization device 90 the same as the thickness dimension (51 μm) of the planarized resin layer 180 that has been planarized by the planarization device 90. Furthermore, the number of passes during the formation of the smooth resin layer 120 is the same as the conventional number of passes, and by increasing the number of passes during the formation of the planarized resin layer 180 compared to the conventional number of passes, the number of passes during the formation of the planarized resin layer 180 becomes greater than the number of passes during the formation of the smooth resin layer 120. This makes it possible to bring the thickness dimension (51 μm) of the planarized resin layer 180 that has been planarized by the planarization device 90 closer to the thickness dimension (66 μm) of the smooth resin layer 120. Furthermore, the thickness dimensions of the flattening resin layers 160 and 170 that are not flattened by the flattening device 90 are set to the thickness dimensions of the flattening resin layer 180 that is flattened by the flattening device 90. To achieve this, the number of passes used to form the flattening resin layers 160 and 170 is reduced compared to conventional methods. The number of passes used to form the smooth resin layer 120 remains the same as conventional methods. Therefore, although the number of passes used to form the flattening resin layers 160 and 170 is less than the number of passes used to form the smooth resin layer 120, the difference between the thickness dimensions of the flattening resin layers 160 and 170 (51 μm) and the smooth resin layer 120 (66 μm) is the same as the difference between the thickness dimensions of the flattening resin layer 180 (51 μm) and the smooth resin layer 120 (66 μm).

[0032] In other words, by adopting this method, the thickness dimensions of the planarized resin layers 160, 170, and 180 are each 51 μm, and the thickness dimension of the smooth resin layer 120 is 66 μm. Therefore, the thickness dimension of the resin layers fluctuates between 51 and 66 μm, and the difference between the maximum and minimum thickness dimensions of the resin layers is 15 μm (= 66 - 51). Thus, while the difference between the maximum and minimum thickness dimensions of the resin layers was 44 μm in the conventional method, in this method it is approximately 1 / 3 (≒ 15 / 44) of that of the conventional method. This makes it possible to reduce the difference in thickness dimensions between the smooth resin layer 120 and the planarized resin layers 160, 170, and 180, and reduces the discrepancy between the actual shape of the formed circuit board and the design model.

[0033] Incidentally, as shown in Figure 2, the control program 118 that controls the operation of the circuit forming apparatus 10 includes a smooth resin layer forming unit 200, a wiring forming unit 202, and a planar resin layer forming unit 204. The smooth resin layer forming unit 200 is a functional unit for forming the smooth resin layer 120. The wiring forming unit 202 is a functional unit for forming wiring 124 on the smooth resin layer 120. The planar resin layer forming unit 204 is a functional unit for forming planar resin layers 160, 170, and 180.

[0034] In the above embodiment, the transport device 20 is an example of a moving device. The pallet 70 is an example of a stage. The inkjet head 88 is an example of an ejection device. The planarization device 90 is an example of a planarization device. The control program 118 is an example of a control program. The wiring 124 is an example of a metal wiring. The smooth resin layer 120 is an example of a smooth resin layer. The planarization resin layers 160, 170, and 180 are examples of planarization resin layers. The first resin layer image data is an example of a first image. The second resin layer image data is an example of a second image. The third resin layer image data is an example of a fourth image. The fourth resin layer image data is an example of a third image. The process performed by the smooth resin layer forming unit 200 is an example of a smooth resin layer forming process. The process performed by the wiring forming unit 202 is an example of a wiring forming process. The process performed by the planarization resin layer forming unit 204 is an example of a planarization resin layer forming process.

[0035] It should be noted that the present invention 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, in the above embodiments, a circuit board is formed consisting only of a smooth resin layer 120 and planar resin layers 160, 170, and 180, but various circuit boards can be formed as long as they include a smooth resin layer 120 and planar resin layers 160, 170, and 180. Specifically, for example, in the circuit board 210 shown in Figure 10, a plurality of planar resin layers 180 are laminated on a pallet 70, and a set of laminates 220 consisting of a smooth resin layer 120 and planar resin layers 160, 170, and 180 is formed on these plurality of planar resin layers 180. Then, four more sets of laminates 220 are laminated on top of the laminates 220. The present invention can also be applied to a circuit board 210 with such a structure. In the above embodiment, the smooth resin layer 120 is formed directly on the pallet, whereas in the circuit board 210, the smooth resin layer 120 is formed indirectly on the pallet 70 via a plurality of planar resin layers 180.

[0036] Furthermore, in the above embodiment, the pallet 70 is moved by the operation of the conveying device 20, but The inkjet head 88 may move, or both the inkjet head 88 and the pallet 70 may move.

[0037] Furthermore, in the above embodiment, an ultraviolet-curable resin is used as the curable resin for forming the resin layer, but various curable resins such as thermosetting resins and two-component mixed resins can be used.

[0038] Furthermore, in the above embodiment, two layers of flattened resin layers that are not flattened by the flattening device 90 are formed between the smooth resin layer 120 and the flattened resin layer 180. However, three or more layers of flattened resin layers that are not flattened by the flattening device 90 may be formed, or only one layer of flattened resin layers that are not flattened by the flattening device 90 may be formed. [Explanation of Symbols]

[0039] 20: Conveying device (moving device) 70: Pallet (stage) 88: Inkjet head (discharge device) 90: Planarization device 118: Control program 120: Smooth resin layer 124: Wiring (metal wiring) 160: Planarized resin layer (planarized resin layer) 170: Planarized resin layer (planarized resin layer) 180: Planarized resin layer (planarized resin layer) 200: Smooth resin layer formation section (planarized resin layer formation process) 202: Wiring formation section (wiring formation process) 204: Planarized resin layer formation section (planarized resin layer formation process)

Claims

1. A smooth resin layer forming step involves moving a dispensing device that dispenses a curable resin and a stage relative to each other according to a first image, thereby dispensing a thin film of curable resin onto the stage to form a smooth resin layer. A wiring formation step of forming metal wiring on the smooth resin layer, A flattened resin layer formation step is performed by moving the discharge device and the stage relative to each other according to a second image to discharge a curable resin in a thin film onto the smooth resin layer, and curing the curable resin without flattening its surface, and then moving the discharge device and the stage relative to each other according to a third image to discharge a curable resin in a thin film, flattening the surface of the curable resin with a flattening device, and then curing it to form a flattened resin layer. Includes, An electrical circuit formation method wherein the number of relative movements between the discharge device and the stage according to the third image is greater than the number of relative movements between the discharge device and the stage according to the second image.

2. The method for forming an electrical circuit according to claim 1, wherein the number of relative movements between the discharge device and the stage according to the second image is less than the number of relative movements between the discharge device and the stage according to the first image.

3. The method for forming an electrical circuit according to claim 1 or claim 2, wherein the number of relative movements between the discharge device and the stage according to the third image is greater than the number of relative movements between the discharge device and the stage according to the first image.

4. The aforementioned flattening resin layer formation step is, The discharge device and the stage are moved relative to each other according to the second image to discharge a curable resin in a thin film onto the smooth resin layer, and the surface of the curable resin is cured without planarization. Then, the discharge device and the stage are moved relative to each other according to the fourth image to discharge a curable resin in a thin film, and the surface of the curable resin is cured without planarization. Then, the discharge device and the stage are moved relative to each other according to the third image to discharge a curable resin in a thin film, and the surface of the curable resin is planarized by a planarization device before curing to form the planarized resin layer. The method for forming an electrical circuit according to any one of claims 1 to 3, wherein the number of relative movements between the discharge device and the stage according to the second image is the same as the number of relative movements between the discharge device and the stage according to the fourth image.

5. A smooth resin layer forming step involves moving a dispensing device that dispenses a curable resin and a stage relative to each other according to a first image, thereby dispensing a thin film of curable resin onto the stage to form a smooth resin layer. A wiring formation step of forming metal wiring on the smooth resin layer, A flattened resin layer formation step is performed by moving the discharge device and the stage relative to each other according to a second image to discharge a curable resin in a thin film onto the smooth resin layer, and curing the curable resin without flattening its surface, and then moving the discharge device and the stage relative to each other according to a third image to discharge a curable resin in a thin film, flattening the surface of the curable resin with a flattening device, and then curing it to form a flattened resin layer. Execute, A control program that controls the operation of a moving device that moves the discharge device and the stage relatively so that the number of relative movements between the discharge device and the stage according to the third image is greater than the number of relative movements between the discharge device and the stage according to the second image.

Images