Inkjet image forming apparatus and control method thereof, circuit board manufacturing method and circuit board

Abstract

The inkjet image forming apparatus (U) of the present invention has a control unit (5). When an insulating material is to be filled into a recess between two adjacent wiring portions formed on a substrate by inkjet printing, the control unit (5) obtains measurement data of the shape of the recess, corrects or supplements the image data of the non-wiring portion pattern based on the measurement data, and performs inkjet printing in the recess based on the corrected or supplemented image data.

Description

Technical Field

[0001] This invention relates to an inkjet image forming apparatus and its control method, as well as a method for manufacturing a circuit board and the circuit board itself. Prior Technology

[0002] In recent years, the demand for thick copper circuit boards has increased significantly in the fields of power components and other technologies. A thick copper circuit board typically refers to a circuit board in which wiring patterns are formed using copper foil with a thickness of 100 μm or more. The general method for manufacturing such a circuit board involves first forming a wiring pattern on the substrate using a conductor (in this case, copper), and then filling the recesses where the wiring pattern is not formed with insulating resin, making the height of the conductor and the insulating resin the same, for example, see Patent Document 1.

[0003] In conventional circuit board manufacturing methods, the process involves applying a uniform layer of insulating resin, such as through screen printing, to the conductors and recesses on the circuit board. The surface layer is then removed, ensuring the height of the insulating resin is the same as the height of the conductors. However, this method suffers from problems such as complex steps and high consumption of insulating resin.

[0004] In light of this background, in recent years, there have been proposals to replace screen printing with inkjet image forming apparatuses for selectively filling recesses with insulating resin. This method, since it eliminates the need to remove the surface layer after the insulating resin is formed on the substrate, improves production efficiency and reduces production costs. [Previous Technical Documents] [Patent Literature]

[0005] Patent Document 1: Japanese Patent Publication No. 2016-064632 Summary of the Invention

[0006] [The problem that the invention aims to solve] However, in the manufacturing process of this type of circuit board, the method generally used is to remove the conductor foil formed on the substrate by etching to form the pattern of wiring portions and non-wiring portions (i.e., recesses).

[0007] Figure 1 is a flowchart illustrating an example of the manufacturing process of a circuit board. The manufacturing process of the circuit board includes, for example, a conductor foil bonding step (step S1), a conductor foil pattern etching step (step S2), a step of embedding insulating resin in the recesses by inkjet printing (step S3), and a prepreg lamination step (step S4).

[0008] However, the inventors' investigation revealed that in this method, if the target thickness of the conductor increases, the etching direction extends not only in the depth direction but also laterally, causing the opening of the recess (i.e., the non-wired portion) to be larger than the design data of the non-wired portion pattern set to the target size. Furthermore, regarding the etching methods used to form wiring, there are wet etching and dry etching, but if the target thickness of the conductor increases, this enlargement of the recess will occur regardless of the method used.

[0009] Therefore, when ink is applied to the recesses using an inkjet image forming apparatus based on the image data created from the design data of the non-wiring section pattern set to the target size, the amount of ink in the recesses becomes insufficient. As a result, the area of ​​insulating resin filled in the recesses becomes more recessed than the wiring section. Furthermore, if prepreg is laminated in the next step under these conditions, defects such as prepreg cracking and migration will occur.

[0010] Here, the design data for the non-wired part pattern is, for example, obtained as negative image information of the design data for the wired part pattern. Furthermore, image data for the non-wired part pattern is calculated from this design data. The image data for the non-wired part pattern is, for example, composed of pixel groups arranged in a matrix (see, for example, Figure 9 described later). Moreover, in this image data, density information corresponding to the inkjet volume is set at the pixel positions corresponding to the inkjet positions within these pixel groups. Hereinafter, the image data created from the design data for the non-wired part pattern will also be simply referred to as "image data for the non-wired part pattern."

[0011] Figure 2 is an example of the shape of the recess between two adjacent wiring portions formed by etching away copper foil during the manufacturing process of the circuit board of Figure 1.

[0012] The left side of Figure 2 shows the measurement results of the surface shape profile of the recesses formed when the copper thickness of the wiring section is 100 μm, 200 μm, and 400 μm. The right side of Figure 2 shows the wiring section pattern as the measurement object. A comb electrode was used as the wiring section pattern as the measurement object here.

[0013] The surface shape profiles in Figure 2 are measured using an optical displacement sensor. In the surface shape profiles of Figure 2, the vertical axis represents the height direction of the substrate, and the horizontal axis represents the horizontal direction of the substrate. The rectangular areas depicted by the overlapping dashed lines in the surface shape profiles of Figure 2 represent the shapes of the recesses shown in the image data of the non-wiring portion pattern.

[0014] As can be seen from Figure 2, the actual recess formed by etching has an opening larger than the image data of the non-wired part pattern. Furthermore, as the copper thickness of the wiring part increases, the opening of the actual recess becomes larger than the image data of the non-wired part pattern. In addition, the actual recess formed by etching has a conical shape.

[0015] Figure 3 (Figures 3A and 3B) illustrates the embedding state of the recesses during ink coating based on image data of the non-wiring pattern in the manufacturing process of the circuit board of Figure 1. Figure 3A shows the embedding state of the recesses when the copper thickness is 100 μm or less. Figure 3B shows the embedding state of the recesses when the copper thickness is 100 μm to 500 μm. Here, as mentioned above, in conventional circuit boards, the conductor thickness is set to 100 μm or less. On the other hand, in thick copper circuit boards used in the field of power devices and the like, the conductor thickness is set to 100 μm to 500 μm.

[0016] Based on this understanding, as shown in Figure 3A, when the copper thickness is less than 100 μm, the depth of the recess is smaller, resulting in less lateral expansion of the recess during etching and less ink deficiency during ink coating. Therefore, the insulating resin filling the recess forms to approximately the same height as the adjacent wiring portion. Thus, after the insulating resin is formed, the overall surface of the substrate, including both wiring and non-wiring portions, is relatively flat. Consequently, problems are less likely to occur during the subsequent steps, such as the deposition of prepreg.

[0017] On the other hand, as shown in Figure 3B, when the copper thickness exceeds 100 μm, the depth of the recess increases, leading to a greater lateral expansion of the recess during etching and a relatively larger deficiency in ink application. Consequently, the insulating resin filling the recess is formed only to a height far below the adjacent wiring portion. Thus, after the insulating resin is formed, the entire upper surface of the substrate, including both wiring and non-wiring portions, becomes significantly uneven. As a result, during the next step of prepreg lamination, issues such as prepreg breakage and displacement can occur.

[0018] The present invention was developed in view of the above-mentioned problems, and its object is to provide an inkjet image forming apparatus and a control method thereof suitable for use in the manufacture of circuit boards. Furthermore, another object of the present invention is to provide a method for manufacturing a circuit board using the image forming apparatus and a circuit board thereof. [Methods used to solve problems]

[0019] The image forming apparatus of the present invention, which is the main type of the invention for solving the aforementioned problems, is applicable to the manufacture of circuit boards, and performs inkjet printing on the recess between two adjacent wiring portions formed on the board; The inkjet-type image forming apparatus includes: The inkjet unit ejects ink droplets made of insulating material toward the aforementioned recess on the aforementioned substrate; and The control unit controls the operation of the inkjet unit based on image data of the non-wiring section pattern, and performs inkjet printing within the aforementioned recess. The aforementioned control unit acquires measurement data of the shape of the aforementioned recess, corrects or supplements the aforementioned image data based on the aforementioned measurement data, and controls the operation of the aforementioned inkjet unit based on the corrected or supplemented image data.

[0020] Furthermore, another aspect of the control method for the image forming apparatus of the present invention is applicable to the manufacture of circuit boards and is used for inkjet image forming apparatus for inkjet printing in a recess between two adjacent wiring portions formed on the board; The control method of the inkjet image forming apparatus involves obtaining measurement data of the shape of the aforementioned recess, correcting or supplementing the image data of the non-wired portion pattern based on the aforementioned measurement data, and controlling the operation of the inkjet unit based on the corrected or supplemented image data to perform inkjet printing within the aforementioned recess.

[0021] Furthermore, another aspect of the present invention is a method for manufacturing a circuit board having a substrate and wiring portions arranged in a pattern on the substrate; in the step of filling an insulating material in the recess between two adjacent wiring portions by inkjet printing, the shape measurement data of the recess is obtained by an inkjet image forming apparatus, and the image data of the non-wiring portion pattern is corrected or supplemented based on the measurement data, and inkjet printing is performed on the recess based on the corrected or supplemented image data.

[0022] Furthermore, another type of circuit board of the present invention is manufactured by the above-described manufacturing method. [Effects of the invention]

[0023] According to the inkjet image forming apparatus of the present invention, it is possible to suppress the formation of unevenness between the wiring portion and the non-wiring portion. Simple Explanation of the Diagram

[0024] Figure 1 is a flowchart illustrating an example of the manufacturing process of a display circuit board. Figure 2 shows an example of the shape of the recess between two adjacent wiring portions formed by etching away copper foil during the manufacturing process of the circuit board of Figure 1. Figure 3A illustrates the embedding state of the recesses during ink coating based on image data of the non-wiring portion pattern in the manufacturing process of the circuit board of Figure 1. Figure 3B illustrates the embedding state of the recesses during ink coating based on image data of the non-wiring portion pattern in the manufacturing process of the circuit board of Figure 1. Figure 4 is a diagram showing the configuration of the image forming apparatus of the first embodiment. Figure 5 is a diagram showing the configuration of the inkjet unit in the first embodiment as viewed from a slightly downward angle. Figure 6 is a schematic diagram showing the configuration of the control system of the image forming apparatus in the first embodiment. Figure 7 is a diagram showing an example of the processing flow executed by the control unit during the recess embedding step in the image forming apparatus of the first embodiment. Figure 8A is a top view of an example of a substrate after the wiring pattern has been formed by etching. Figure 8B is a cross-sectional view along the short side of an example of a substrate after the wiring pattern has been formed by etching. Figure 9 is an example of image data of the original non-wiring pattern used when embedding the recesses shown in Figures 8A and 8B by ink coating. Figure 10 is a diagram showing the processing flow executed by the control unit during the recess embedding step in the image forming apparatus of the second embodiment. Figures 11A, 11B, 11C, 11D, and 11E are schematic diagrams showing the recess installation steps of the second embodiment. Figures 12A, 12B, 12C, 12D, and 12E are schematic diagrams showing the steps of embedding the recess in modified Example 1. Figures 13A, 13B, 13C, 13D, and 13E are schematic diagrams showing the steps of embedding the recess in modified example 2. Implementation

[0025] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, in the drawings of this specification, redundant descriptions of constituent elements having substantially the same function are omitted by using the same symbols.

[0026] [First Implementation Type] First, the configuration of an inkjet image forming apparatus (hereinafter also referred to as "image forming apparatus U") according to an embodiment of the present invention will be described.

[0027] Figure 4 is a diagram showing the configuration of the image forming apparatus U. Figure 5 is a diagram showing the configuration of the inkjet unit 1 as viewed from a slightly lower angle. Figure 6 is a schematic diagram showing the configuration of the control system of the image forming apparatus U. Here, three mutually orthogonal axes (X-axis, Y-axis, and Z-axis) are defined as shown in Figure 4. The Z-axis direction corresponds to the vertical upward direction, and the X-axis and Y-axis directions correspond to the horizontal directions perpendicular to the vertical upward direction.

[0028] The image forming apparatus U is applicable, for example, to the manufacture of circuit boards. Specifically, the image forming apparatus U is used, for example, in step S3 of the manufacturing process in FIG1, as a manufacturing apparatus for filling the recess between two adjacent wiring portions formed on the substrate P by ink coating with insulating resin.

[0029] Here, the substrate P, which is to be coated with ink by the image forming apparatus U, is the substrate after the wiring pattern is formed on its upper surface in the conductor foil etching step of step S2 of the manufacturing steps in FIG1. ​​That is, a recess (i.e., a non-wiring portion) is formed between two adjacent wiring portions of the wiring pattern on the substrate P.

[0030] The substrate P used in this invention is not particularly limited; any substrate commonly used for printed circuit boards may be used. For example, a glass epoxy board can be used for such a substrate P.

[0031] In addition, the conductor thickness of the wiring portion on the substrate P is set to, for example, 100 to 5000 μm, which is suitable for thick copper circuit substrates. It is assumed that when etching is performed on a conductor foil with a conductor thickness of 100 μm, the recess will be a distance including a 100 μm horizontal extension to the left and right sides. Therefore, the width of the recess on the substrate P will be more than 200 μm.

[0032] The image forming apparatus U-series includes an inkjet unit 1, a shape measuring unit 2, a drive unit 3, a control unit 5, and an external input / output unit 6.

[0033] <Drive Section 3> The drive unit 3 moves the inkjet unit 1 relative to the substrate P. Specifically, the drive unit 3 has an X-direction drive unit 31 and a Y-direction drive unit 32.

[0034] The Y-direction drive unit 32 is, for example, built into a platform 41 that is horizontally arranged relative to the bottom surface of the image forming apparatus U. The Y-direction drive unit 32 is configured to have a stage 341 for mounting a substrate P, and the stage 341 can move linearly along the Y-axis direction.

[0035] The X-direction drive unit 31 is, for example, mounted between two supports 42 extending vertically relative to the platform 41. The X-direction drive unit 31 holds the inkjet unit 1 by its output section and causes the inkjet unit 1 to move linearly along the X-axis.

[0036] In addition, the drive unit 3 has an R-direction drive unit (not shown) that can rotate the stage 341 around the Z-axis, and can adjust the deflection degree of the rotation direction of the substrate P placed on the stage 341.

[0037] Thus, the image forming apparatus U has drive units 3 in each direction (X direction, Y direction) of the X direction drive unit 31 and the Y direction drive unit 32. By combining the movements of these drive units 3 in each direction, the inkjet unit 1 and the shape measuring unit 2 can be moved relative to the substrate P.

[0038] <Inkjet Section 1> The image forming apparatus U of this embodiment has a printing head that integrates an inkjet unit 1 and a shape measuring unit 2.

[0039] The inkjet unit 1 has an inkjet head 11 and an ink reservoir 12. The inkjet head 11 has a plurality of inkjet nozzles 111 on its lower surface. Furthermore, the inkjet head 11 receives ink from the ink reservoir 12 and selectively jets ink from the plurality of inkjet nozzles 111 to coat the substrate P with ink of a predetermined pattern, thereby forming an image on the surface of the substrate P.

[0040] For ink ejected from the recesses (i.e., non-wired areas) formed on substrate P, various insulating compounds, such as inorganic and organic compounds, can be used. Examples of inorganic compounds include inorganic oxides. Examples of organic compounds include resins such as polyimide, polyamide, polyester, and polyacrylate, as well as photocurable and thermocurable compounds. For inkjet inks, considering the reduction of viscosity, compositions composed of photocurable monomers such as acrylic monomers and epoxy monomers, thermocurable monomers, photopolymerization initiators, and thermal polymerization initiators are preferred. If the ink is a substantially non-volatile solvent-free insulating ink, the amount of liquid applied will directly become a solid component as an insulating material, thus making it a preferred planarizing agent for thick copper recesses. Furthermore, considering heat resistance and electrical reliability, epoxy compounds and epoxy monomers are preferred. Moreover, it is preferable to photocur after planarization coating and to perform heat treatment thereafter. The strength of insulation materials can be increased through heat treatment.

[0041] In this embodiment, for example, an ink with a curable insulating monomer as the main component is used as the ink sprayed onto the recess formed on the substrate P. However, as mentioned above, as for the ink sprayed onto the recess formed on the substrate P, if it wets and spreads to the surrounding area from the spraying position when it is sprayed into the recess on the substrate P, and is fixed onto the substrate P by performing photocuring or heat curing treatment, then any ink can be used.

[0042] <Shape Measuring Unit 2> The shape measuring unit 2 is configured, for example, using a conventional optical displacement sensor having a light-emitting unit 21 and a light-receiving unit 22. The shape measuring unit 2 emits laser light downward along the Z-axis direction from the light-emitting unit 21, and receives the light diffused and reflected from the surface of the substrate P by means of the light-receiving unit 22 having a line sensor, a lens, etc. In this way, the shape measuring unit 2 determines the distance in the Z-axis direction from the inkjet unit 1 to the surface of the substrate P by means of, for example, triangulation.

[0043] The shape measuring unit 2 is integrally disposed with the inkjet unit 1 and is controlled by the drive unit 3 to move relative to the substrate P. The shape measuring unit 2 moves under the action of the drive unit 3 and is controlled to scan the XY plane (that is, scan the X and Y directions) to measure the distance in the Z-axis direction of each point (X, Y). In this way, the shape measuring unit 2 measures the distance in the Z-axis direction from the print head to the surface of the substrate P at a plurality of points (X, Y) in the XY plane, thereby measuring the surface shape of the substrate P.

[0044] That is, the shape measuring unit 2 measures the shape of the actual recess formed on the substrate P in the conductor foil etching step of step S2 in FIG1.

[0045] In addition, an example of a shape measuring unit 2 being composed of an optical sensor using a triangulation method has been described here. However, it is not limited to this example. Other optical sensors, such as confocal optical sensors, or contact sensors, ultrasonic sensors, etc., may also be used for the shape measuring unit 2.

[0046] <External Input / Output Section 6> The external input / output unit 6 is provided inside the main body of the image forming apparatus U as part of the main body, and / or separately outside the main body. The external input / output unit 6 functions as an interface for the operator of the image forming apparatus U. That is, the external input / output unit 6 has a display unit such as a monitor and lights, and an input unit such as a keyboard.

[0047] <Control Section 5> The control unit 5 controls all parts of the image forming apparatus U. The control unit 5 includes various controllers 511, 521, and 531, various drivers 512, 522, and 532, a CPU 54, a semiconductor memory 55, and an auxiliary memory unit 56 for controlling the image forming apparatus U. Regarding the various controllers, the control unit 5 includes an inkjet control controller 511, a shape measurement control controller 521, and a drive control controller 531. Furthermore, regarding the various drivers, the control unit 5 includes an inkjet control driver 512, a shape measurement control driver 522, and a drive control driver 532.

[0048] The semiconductor memory 55 and / or auxiliary memory 56 store programs for controlling the inkjet printing action of the inkjet unit 1, controlling the measurement action of the shape measuring unit 2, and controlling the drive of the drive unit 3. In addition, they store programs for creating surface shape data from the distance information obtained by the shape measuring unit 2, programs for matching image data with it, and programs for determining the printing order based on such data.

[0049] The CPU 54 executes a program that has scheduled the printing order, processes the data in the memory 55 sequentially, and outputs control signals to various controllers 511, 521, and 531. Each controller 511, 521, and 531 processes the control signals and transmits the signals used to actually drive the inkjet unit 1, the shape measuring unit 2, and the drive unit 3 to various drivers 512, 522, and 532. The various drivers 512, 522, and 532 then drive the inkjet unit 1, the shape measuring unit 2, and the drive unit 3.

[0050] Furthermore, the inkjet unit 1, shape measuring unit 2, and drive unit 3 transmit signals to the controllers 511, 521, and 531 via the drivers 512, 522, and 532 as needed. The control unit 5 then uses these signals to provide feedback on new control signals to the various controllers 511, 521, and 531, and saves these signals as data.

[0051] The image forming apparatus U of this embodiment performs the operation of measuring the shape of a recess formed on a substrate P and the operation of inkjet printing into the recess formed on the substrate P. The control unit 5 controls the inkjet unit 1, the shape measuring unit 2, and the drive unit 3 to perform these operations.

[0052] <Details of the control measures implemented via Control Unit 5> Referring to Figures 7 to 9, the control state of the control unit 5 for embedding the recess in step S3 of Figure 1 is described here.

[0053] Figure 7 is a diagram showing an example of the processing flow executed by the control unit 5 during the recess installation step. The operation flow in Figure 7 is, for example, the processing executed sequentially by the control unit 5 according to a computer program.

[0054] Figures 8A and 8B are a top view and a cross-sectional view along the short side of a substrate P after a wiring pattern has been formed by etching. In Figures 8A and 8B, H1 represents the wiring area, and H2 represents the non-wiring area (i.e., the recessed area). Furthermore, in Figure 8B, H2a represents the shape of the recess based on the image data of the non-wiring pattern.

[0055] Figures 8A and 8B show that the recess H2 has a tapered shape due to the etching effect, resulting in an opening width that is wider than the design data of the non-wired part pattern. Here, the design data of the non-wired part pattern is set as vertical dimension × horizontal dimension: 2mm × 0.4mm.

[0056] Figure 9 is an example of image data (original data) of the non-wiring pattern used when embedding the recess H2 shown in Figures 8A and 8B by ink coating.

[0057] Here, the image data is set to be inkjet-jet printed over an area with dimensions of 2mm x 0.4mm, corresponding to the design data of the non-wired portion pattern of the recess H2. Furthermore, the image data is a grayscale data with a resolution of 1440dpi and different tones. Each pixel area of ​​this image data corresponds to an inkjet position. Moreover, the density of each pixel area represents the amount of inkjet printed at each inkjet position.

[0058] However, the total amount of ink ejected for the concave portion H2 can also be set as the droplet ejection density. In this case, the image data can also be displayed as a binary image, and the amount of ink ejected can be adjusted based on the pixel distribution on the image data.

[0059] In step S11, the control unit 5 uses the shape measurement unit 2 to measure the surface shape on the substrate P on which the wiring pattern is formed, thereby measuring the shape of the recess H2 formed on the substrate P and obtaining measurement data of the surface shape profile as shown in FIG2. Hereinafter, the measurement data obtained from the measurement results will also be referred to as "measurement data of the shape of the recess".

[0060] In step S12, the control unit 5 calculates the estimated amount of ink required to fill the recess H2 based on the measurement data of the shape of the recess H2. Here, the amount of ink estimated based on the measurement data of the shape of the recess H2 to fill the recess H2 is referred to as the "actual value of the required amount of ink".

[0061] In step S12, the control unit 5 calculates the volume of the recess H2 based on the measurement data of the shape of the recess H2, and calculates the actual value of the required amount of ink from the volume.

[0062] In step S13, the control unit 5 calculates the estimated amount of ink required to fill the recess H2 based on the image data of the non-wiring pattern. As described above, the image data of the non-wiring pattern specifies the ink ejection amount at each position within the recess H2, calculated from the design data of the non-wiring pattern. The design data of the non-wiring pattern can be obtained, for example, from the negative image information of the design data of the wiring pattern. Here, the amount of ink estimated based on the image data of the non-wiring pattern for filling the recess H2 will also be referred to as the "preliminary estimate of the required ink amount".

[0063] In step S13, the control unit 5 calculates the volume of the recess H2a based on image data of the non-wiring part pattern, and calculates a pre-estimated value of the required amount of ink from the volume.

[0064] In step S14, the control unit 5 calculates the shortfall of the pre-estimated value of the required ink amount relative to the actual value of the required ink amount.

[0065] As described above, the image data of the non-wired portion pattern (Fig. 9) does not take into account the lateral expansion of the recess during etching. Therefore, the pre-estimated value of the required ink amount calculated from the image data of the non-wired portion pattern will be less than the actual value of the required ink amount calculated from the measurement data of the shape of the recess H2. This insufficient amount is calculated in step S14.

[0066] In step S15, the control unit 5 corrects or supplements the image data of the non-wiring portion pattern based on the insufficient amount calculated in step S14. That is, through this correction or supplement, the total amount of ink ejected when inkjet is performed based on the image data of the non-wiring portion pattern becomes an appropriate amount that matches the actual shape of the recess H2.

[0067] In this step S15, the control unit 5 corrects or supplements the image data so that the height difference between the top of the insulating resin in the recess H2 and the top of the wiring portion when the insulating resin fills the recess H2 is within ±50μm.

[0068] Here, three methods can be listed as follows regarding the techniques for modifying or supplementing the image data of non-wiring part patterns.

[0069] The first method involves adjusting the total amount of ink ejected into the recess H2 by correcting the density on the image data. In the image data, for example, the amount of ink ejected into the recess H2 is represented as shown in Figure 9, which is the density (i.e., pixel value) of each pixel position on the image data.

[0070] That is, in the first method, the control unit 5 corrects the image data so that the concentration increases to correspond to the insufficient amount calculated in step S14. At this time, the control unit 5 can, for example, increase the concentration of the image data of the non-wiring pattern at each ejection position to correspond to the insufficient amount. In this way, the control unit 5 controls the inkjet unit 1 to perform inkjeting (i.e., multi-drop mode) at each pixel position with a number of droplets corresponding to the concentration.

[0071] The second method involves adjusting the total amount of ink ejected into the recess H2 by correcting the droplet distribution density on the image data.

[0072] That is, in the second method, the control unit 5 corrects the image data to, for example, increase the droplet distribution density on the image data to the amount of deficiency calculated in step S14. At this time, the control unit 5 may, for example, be set to increase the number of pixels in the image data, and perform inkjet printing on each pixel of the increased pixel group.

[0073] The third method involves creating supplementary image data in addition to the image data, corresponding to the insufficient amount calculated in step S14, and then performing additional inkjet printing based on the supplementary image data, thereby adjusting the total amount of ink ejected into the recess H2.

[0074] In the third method, for example, the control unit 5 can make supplementary image data so that the ink amount is evenly distributed to correspond to the insufficient amount for each ejection position of the image data of the non-wiring part pattern. In this way, the control unit 5 performs inkjet printing on the substrate P according to the image data and then performs additional inkjet printing on the substrate P according to the supplementary image data.

[0075] In step S16, the control unit 5 uses the corrected or supplemented image data to perform inkjet printing on the recess formed on the substrate P.

[0076] The ink used to fill the recess H2 is typically a low-viscosity ink, which will smooth out after adhesion. Therefore, even if the tapered portion of the recess H2 is not directly inkjet-sprayed, the insulating resin filling the recess H2 will eventually achieve a uniform height.

[0077] Furthermore, in step S16, the control unit 5 performs inkjet processing on the recess using the corrected or supplemented image data, which is the same as normal inkjet processing.

[0078] For example, the control unit 5 moves the inkjet unit 1 a predetermined distance along the X-axis from left (-X) to right (+X) each time, while simultaneously performing inkjet printing from the inkjet unit 1 at various positions. Furthermore, when completing the drawing of a line, the control unit 5 moves the inkjet unit 1 to a position that advances a predetermined distance in the +Y direction to perform the drawing of the next line. Moreover, the control unit 5 again moves a predetermined distance along the X-axis from right (+X) to left (-X) each time, while simultaneously performing inkjet printing from the inkjet unit 1 at various positions.

[0079] In this embodiment, the control unit 5 causes the inkjet unit 1 to move 17.6 μm (equivalent to one pixel of 1440 dpi) on the substrate P each time, while simultaneously performing inkjet printing from the inkjet unit 1 at various positions.

[0080] Here, in step S16, as described above, the control unit 5 can also use a multi-pass inkjet method instead of a single-pass method. Furthermore, although not shown, the control unit 5 can also arrange four 360dpi inkjet units 1 longitudinally, staggered by 17.6μm along the Y-axis, and coat 1440dpi in one pass with the four inkjet units 1.

[0081] In this embodiment, the control unit 5 uses the above method to fill the recess H2 formed on the substrate P with insulating resin by inkjet printing. This forms the insulating resin filling the recess H2 to a height approximately the same as the adjacent wiring portion H1. The substrate P, with the insulating resin filling the recess H2, is then fed to the subsequent prepreg lamination apparatus for prepreg lamination processing in step S4 of the manufacturing process shown in FIG. 1.

[0082] Although the above implementation is not described here, the ink on the substrate P can also be dried by irradiating the ink coating area on the substrate P with UV light or by performing heat treatment before the prepreg is pressed onto the substrate P.

[0083] Furthermore, from the viewpoint of preventing a decrease in the operating speed of the image forming apparatus U due to useless calculation processing, the control unit 5 can also determine in step S14 whether to correct or supplement the image data based on the amount of deficiency between the pre-estimated value of the required ink volume and the actual value of the required ink volume. For example, if the pre-estimated value of the required ink volume is more than 10% less than the actual value of the required ink volume, the control unit 5 performs inkjet printing on the recess H2 after correcting or supplementing the image data. On the other hand, if the pre-estimated value of the required ink volume is less than 10% less than the actual value of the required ink volume, the control unit 5 performs inkjet printing on the recess H2 without correcting or supplementing the image data. According to the inventors' experimental results, when the deficiency is less than 10%, the subsequent prepreg formed on the substrate P is less prone to cracking, displacement, etc.

[0084] <Efficacy> In summary, the inkjet image forming apparatus U of this embodiment includes: The inkjet unit 1 ejects ink droplets made of insulating material toward a recess on the substrate P; and The control unit 5 controls the operation of the inkjet unit 1 based on the image data of the non-wiring section pattern, and performs inkjet printing within the recess; The control unit 5 obtains measurement data of the shape of the aforementioned recess, corrects or supplements the aforementioned image data based on the measurement data, and controls the operation of the inkjet unit 1 based on the corrected or supplemented image data.

[0085] According to the image forming apparatus U of this embodiment, the amount of ink sprayed onto the insulating resin in the recess H2 can be appropriately adjusted, and the insulating resin formed in the recess H2 can be positioned at approximately the same height as the adjacent wiring portion H1. This allows the entire upper surface of the insulating resin, including both the wiring portion H1 and the non-wiring portion H2, to be flat. In other words, this prevents the prepreg formed on the substrate P during subsequent lamination from cracking, shifting, or other damage.

[0086] [Second Implementation Mode] The inkjet control described above is effective in terms of production efficiency because it can complete inkjet printing in a single pass within the recess.

[0087] However, the inkjet control in the above embodiment does not adjust the inkjet position to match the actual shape of the recess. Therefore, when the actual recess expands significantly in the horizontal direction compared to the shape of the recess specified in the image data of the non-wiring part pattern, the inkjet volume adjustment method in the above embodiment may result in the inkjet insulating resin not being able to reach the end position within the recess smoothly.

[0088] The inkjet control system of this embodiment takes this viewpoint into account and adjusts the inkjet position according to the actual shape of the recess to perform inkjet printing within the recess.

[0089] Figure 10 is a diagram showing an example of the processing flow executed by the control unit 5 of this embodiment during the recess embedding step.

[0090] Figures 11A to 11E are schematic diagrams illustrating the recess embedding steps of this embodiment. The inkjet processing in Figures 11A to 11E is performed based on a plurality of fine image data produced according to the processing flow in Figure 10. Here, the right side of Figures 11A to 11E shows fine image data produced according to the shape of the recess H2 at each height position. Fine image data f1, f2, f3, and f4 are respectively fine image data for the first layer, the second layer, the third layer, and the fourth layer of ink layers laminated and formed within the recess H2.

[0091] In step S21, the control unit 5 uses the shape measuring unit 2 to measure the surface shape on the substrate P on which the wiring pattern is formed. This allows for the measurement of the shape of the recess H2 formed on the substrate P.

[0092] In step S22, the control unit 5 divides the image data of the non-wiring part pattern into a plurality of fine image data corresponding to each height position of the recess H2 (in this case, it is divided into four fine image data f1, f2, f3, and f4).

[0093] Here, in step S22, the control unit 5 can also divide the image data of the non-wiring pattern into segments according to the number of fine image data generated (four in this case), and set the density of each pixel position of the plurality of fine image data. In this way, the total ink volume after inkjet printing is adjusted according to the four fine image data f1, f2, f3, and f4 respectively.

[0094] In step S23, the control unit 5 corrects a plurality of fine image data (here, four fine image data f1, f2, f3, and f4) based on the measurement data of the shape of the recess H2, so that the inkjet can also reach the area of ​​the recess H2 that has been expanded due to etching.

[0095] Here, the original image data of the non-wiring section pattern is set to be inkjet printed in an area with a vertical dimension × horizontal dimension of 2mm × 0.4mm. However, the actual shape of the recess H2 is as shown in Figures 11A to 11E. Since it has a conical shape, when inkjet printing with the original image data, the total inkjet volume will be insufficient when inkjet printing into the recess H2, resulting in a depression in the recess H2.

[0096] In response, in step S23, the control unit 5 corrects the inkjet positions in a plurality of fine image data (in this case, four fine image data f1, f2, f3, and f4) based on the measurement data of the shape of the recess H2. Specifically, for example, the control unit 5 sets the fine image data f1 for the first layer of ink layer formed in the recess H2 to be inkjet at the originally set size without correction. Furthermore, the control unit 5 corrects the fine image data f2 for the second layer to be inkjet in an area with a vertical dimension × horizontal dimension of 2 mm × 0.5 mm. Furthermore, the control unit 5 corrects the fine image data f3 for the third layer to be inkjet in an area with a vertical dimension × horizontal dimension of 2 mm × 0.6 mm. Furthermore, the control unit 5 corrects the fine image data f4 for the fourth layer to be inkjet in an area with a vertical dimension × horizontal dimension of 2 mm × 0.7 mm. Here, the inkjet amount for the extended area is appropriately set according to the volume of that area.

[0097] In step S24, the control unit 5 performs inkjet printing on the recess H2 multiple times based on the multiple fine image data corrected in step S23. That is, ink is deposited and coated on the recess H2.

[0098] In summary, the image forming apparatus U of this embodiment, like the image forming apparatus U of the first embodiment, can also appropriately adjust the amount of ink sprayed onto the insulating resin in the recess H2, and can make the insulating resin formed in the recess H2 at approximately the same height as the adjacent wiring portion H1.

[0099] Here are some other preferred embodiments of inkjet control in the second implementation.

[0100] <Variation Example 1> Figures 12A to 12E are schematic diagrams showing the steps of embedding the recess in modified example 1.

[0101] In the second embodiment of inkjet control, when the control unit 5 is about to form the outermost layer in the recess H2, it is preferable that the thickness of the outermost layer is less than the thickness of the lower layer in the recess H2 when performing inkjet printing in the recess H2.

[0102] At this time, the control unit 5 adjusts, for example, the ratio of the density of each fine image data so that the total thickness of the fine image data f4 used to form the outermost layer, which is used to embed the recess H2, is less than the fine image data f1, f2, and f3 used to form the lower layer.

[0103] In this way, the control unit 5 can, for example, make the amount of ink sprayed based on the fine image data f4 used when forming the outermost layer less than the amount of ink sprayed based on the fine image data f1, f2, f3 used when forming the lower layer in the recess H2.

[0104] According to the inkjet method of this modified example, the insulating resin filling the recess H2 can be formed more smoothly. Furthermore, according to this inkjet method, the height of the insulating resin filling the recess H2 can be easily adjusted.

[0105] <Variation Example 2> Figures 13A to 13E are schematic diagrams showing the steps of embedding the recess in modified example 2.

[0106] In the second embodiment of inkjet control, when the control unit 5 is to form the outermost layer within the recess H2, it is preferable to perform inkjet printing only on an area narrower than the area of ​​the recess H2.

[0107] At this time, the inkjet area of ​​the fine image data f4 used by the control unit 5 system when the outermost layer is about to be formed is limited to a narrower area than the area of ​​the recess H2 that is actually measured.

[0108] According to the inkjet method of this modified example, the wetting and spreading of the insulating resin filling the recess H2 to the wiring portion H1 can be prevented, thus preventing the formation of a raised area on the wiring portion H1.

[0109] (Other implementation methods) The present invention is not limited to the above-described embodiments but can also be applied to various variations.

[0110] For example, the above embodiment shows an image forming apparatus U using the shape measuring unit 2 to measure the shape of an actual recess formed on a substrate P. However, the shape measuring device for measuring the surface shape of the substrate P can also be provided separately from the image forming apparatus U. In this case, the image forming apparatus U can obtain the measurement data of the surface shape of the substrate P from the shape measuring device.

[0111] The specific examples of the present invention have been described in detail above; however, these examples are merely illustrative and are not intended to limit the scope of the patent application. The technology described in the patent application also includes variations and modifications of the specific examples described above.

[0112] This case references the disclosures in the specification, drawings, and abstract contained in Japanese Patent Application No. 2024-59686, filed on April 2, 2024. [Industry availability]

[0113] According to the inkjet image forming apparatus of the present invention, it is possible to suppress the formation of unevenness between the wiring portion and the non-wiring portion.

[0114] 1: Inkjet section 2: Shape Measurement Unit 3: Drive Unit 5: Control Department 6: External Input / Output Section 11: Inkjet Head 12: Ink Storage Section 21:Light projection department 22: Light-receiving part 31: X-direction drive unit 32: Y-direction drive unit 41: Platform 42: Bracket 54: CPU 55: Semiconductor memory (memory) 56: Assistive Memory Department 111: Inkjet Nozzle 341: Platform 511: Inkjet control controller (controller) 512: Inkjet Control Driver (Driver) 521: Controller for shape measurement control (controller) 522: Shape Measurement Control Actuator (Actuator) 531: Drive control controller (controller) 532: Drive control driver (driver) f1, f2, f3, f4: Fine image data H1: Wiring section H2, H2a: Recessed portion (non-wiring portion) P: Substrate U: Image forming apparatus S1, S2, S3, S4, S11, S12, S13, S14, S15, S16, S21, S22, S23, S24: Steps

Claims

1. An image forming apparatus suitable for manufacturing a circuit board, for inkjet printing into a recess between two adjacent wiring portions formed on the board; the inkjet image forming apparatus comprises: an inkjet unit that ejects ink droplets made of an insulating material toward the recess on the board; and a control unit that controls the operation of the inkjet unit based on image data of a non-wiring portion pattern, and performs inkjet printing into the recess; the control unit acquires measurement data of the shape of the recess, corrects or supplements the image data based on the measurement data, and controls the operation of the inkjet unit based on the corrected or supplemented image data.

2. The image forming apparatus as claimed in claim 1, wherein, The aforementioned control unit corrects or supplements the aforementioned image data to make up for the deficiency of the second ink estimate relative to the first ink estimate, wherein the first ink estimate is the amount of ink required to fill the aforementioned recess calculated from the aforementioned measurement data, and the second ink estimate is the amount of ink required to fill the aforementioned recess calculated from the aforementioned image data.

3. The image forming apparatus as claimed in claim 2, wherein, The aforementioned control unit adjusts the total amount of ink ejected into the aforementioned recess by correcting the density of the aforementioned image data.

4. The image forming apparatus as claimed in claim 2, wherein, The aforementioned control unit adjusts the total amount of ink ejected into the aforementioned recess by correcting the droplet distribution density on the aforementioned image data.

5. The image forming apparatus as claimed in claim 2, wherein, In addition to the aforementioned image data, the aforementioned control unit generates supplementary image data corresponding to the aforementioned insufficient amount, and performs additional inkjet printing based on the aforementioned supplementary image data, thereby adjusting the total amount of ink ejected into the aforementioned recess.

6. The image forming apparatus as claimed in claim 2, wherein, When the aforementioned control unit is 10% or more deficient in the amount of the second ink push measurement relative to the amount of the first ink estimate, it performs inkjet printing on the aforementioned recess after correcting or supplementing the aforementioned image data; and when the deficient in the amount of the second ink push measurement relative to the amount of the first ink estimate is less than 10%, it performs inkjet printing on the aforementioned recess without correcting or supplementing the aforementioned image data.

7. The image forming apparatus as claimed in claim 1, wherein, The aforementioned control unit divides the aforementioned image data into a plurality of fine image data corresponding to each height position of the aforementioned recess, and, in accordance with the shape of the aforementioned recess specified by the aforementioned measurement data, corrects the inkjet positions specified by the plurality of fine image data respectively; and, based on the aforementioned plurality of fine image data, divides the inkjet process for the aforementioned recess into a plurality of times, and deposits ink layers into the aforementioned recess.

8. The image forming apparatus as claimed in claim 7, wherein, The aforementioned control unit processes the aforementioned plurality of fine image data such that the thickness of the outermost layer in the aforementioned recess is less than the thickness of the lower layer in the aforementioned recess.

9. The image forming apparatus as claimed in claim 7, wherein, The aforementioned control unit, for the outermost layer within the aforementioned recess, creates the aforementioned plurality of fine image data into a position where the end region of the aforementioned recess, as specified by the aforementioned measurement data, is a position where inkjet printing is not performed.

10. The image forming apparatus as claimed in claim 1, wherein, The conductor thickness of the aforementioned wiring section is between 100 and 5000 μm.

11. The image forming apparatus as claimed in claim 1, wherein, The aforementioned control unit corrects or supplements the aforementioned image data so that when the aforementioned insulating material is filled into the aforementioned recess, the height difference between the top of the aforementioned insulating material in the aforementioned recess and the top of the aforementioned wiring portion is within ±50μm.

12. The image forming apparatus as claimed in claim 1, wherein, The width of the aforementioned recess is 200 μm or more.

13. The image forming apparatus as claimed in claim 1, wherein, The patterns of the aforementioned wiring portion and the aforementioned recessed portion are formed by etching the conductor foil attached to the aforementioned substrate.

14. A control method for an image forming apparatus, applicable to the manufacture of a circuit board, for inkjet printing into a recess between two adjacent wiring portions formed on the board; the control method for the inkjet image forming apparatus involves obtaining measurement data of the shape of the recess, correcting or supplementing image data of a non-wiring portion pattern based on the measurement data, and controlling the operation of the inkjet unit based on the corrected or supplemented image data to perform inkjet printing into the recess.

15. A method for manufacturing a circuit board, comprising manufacturing a circuit board having a substrate and wiring portions arranged in a pattern on the substrate; in the step of filling an insulating material in a recess between two adjacent wiring portions by inkjet printing, measuring data of the shape of the recess is obtained by an inkjet image forming apparatus, and image data of non-wiring portion patterns is modified or supplemented based on the measuring data, and inkjet printing is performed on the recess based on the modified or supplemented image data.

16. A circuit board manufactured by the manufacturing method described in claim 15.

Images