Printing method and inkjet recording device

Abstract

Provided are a printing method and inkjet recording device capable of more reliably printing on a printing medium surface having a step. The printing method comprises discharging ink onto a substrate (S) having a step portion, wherein the step portion comprises three regions: an inclined portion (E) constituting the step, an upper adjacent portion (UC) of a predetermined width adjacent to the inclined portion (E), and a lower adjacent portion (LC) of a predetermined width adjacent to the inclined portion (E). The method includes a discharge amount setting step for increasing the amount of ink droplets discharged per ink discharge cycle for at least one selected region among the three regions compared to the amount of ink droplets discharged for regions other than the three regions.

Description

Technical Field

[0001] The present invention relates to a printing method and an inkjet recording device. Background Art

[0002] Patent Document 1 discloses a technique for printing by discharging ink onto a three-dimensionally structured printing medium. This technique involves discharging more ink toward the center of a convex portion than toward its end, to prevent ink from flowing from the convex portion into the concave portion, thereby preventing the convex portion from being insufficiently filled with ink.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-202635

[0004] However, if ink flows down the stepped portion of the three-dimensional structure, the ink tends to flow down at the corners of the stepped portion, and sometimes no ink remains and the print medium surface is exposed, which makes it impossible to reliably perform desired printing. Summary of the Invention

[0005] An object of the present invention is to provide a printing method and an inkjet recording apparatus that can more reliably print on a printing medium surface having steps.

[0006] In order to achieve the above-mentioned object, the invention described in claim 1 is a printing method for discharging ink onto a substrate having a stepped portion.

[0007] The step portion includes three areas: an inclined portion constituting a step, an upper adjacent portion of a predetermined width adjacent to the inclined portion, and a lower adjacent portion of a predetermined width adjacent to the inclined portion.

[0008] The printing method includes a discharge amount setting step, in which the amount of ink droplets discharged per ink discharge cycle to at least any one selected area among the three areas is increased compared to the amount of ink droplets discharged to areas other than the three areas.

[0009] In addition, the invention described in claim 2 is a printing method described in claim 1,

[0010] The above ink contains a gelling agent.

[0011] In addition, the invention described in claim 3 is a printing method described in claim 1 or 2,

[0012] The distribution of the ink droplet amount in the selected area is non-uniform.

[0013] In addition, the invention described in claim 4 is a printing method described in claim 3,

[0014] The selected area includes at least two of the three areas mentioned above.

[0015] The ink droplet amounts for each of the at least two regions include mutually different ink droplet amounts.

[0016] Furthermore, the invention according to claim 5 is a printing method according to any one of claims 1 to 4,

[0017] The selected area is determined according to the material of the substrate.

[0018] Furthermore, the invention according to claim 6 is a printing method according to any one of claims 1 to 5,

[0019] The base material is a wiring substrate including an insulating substrate and wiring conductors located on the insulating substrate.

[0020] The above ink is solder resist ink.

[0021] In addition, the invention described in claim 7 is a printing method described in any one of claims 1 to 6,

[0022] The ink is cured by irradiation with predetermined energy rays.

[0023] In addition, the invention described in claim 8 is a printing method described in claim 7,

[0024] The above-mentioned prescribed energy rays are ultraviolet rays.

[0025] In addition, the invention described in claim 9 is a printing method described in any one of claims 1 to 8,

[0026] The above ink is thermosetting.

[0027] Furthermore, the invention according to claim 10 is an inkjet recording device comprising:

[0028] a discharge action portion for discharging ink; and

[0029] Control Department,

[0030] When printing is performed by ejecting ink onto a substrate having a stepped portion having three regions including an inclined portion constituting a step, an upper adjacent portion of a predetermined width adjacent to the inclined portion, and a lower adjacent portion of a predetermined width adjacent to the inclined portion,

[0031] The control unit increases the amount of ink droplets discharged per ink discharge cycle to at least any one selected area among the three areas compared to the amount of ink droplets discharged to areas other than the three areas.

[0032] According to the present invention, there is an effect that printing can be performed more reliably on a printing medium surface having steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1A It is a front view illustrating a schematic configuration of an inkjet recording apparatus according to an embodiment of the present invention.

[0034] Figure 1B It is a top view of the inkjet recording device.

[0035] Figure 2 This is a block diagram showing the functional configuration of an inkjet recording device.

[0036] Figure 3A This is a diagram illustrating the printing range of a wiring substrate.

[0037] Figure 3B This is a diagram illustrating the printing range of a wiring substrate.

[0038] Figure 4 Three types of ink discharge amount distribution examples are shown.

[0039] Figure 5A It is a diagram explaining the increase in the ink discharge amount.

[0040] Figure 5B It is a diagram explaining the increase in the ink discharge amount.

[0041] Figure 5C It is a diagram explaining the increase in the ink discharge amount.

[0042] Figure 6 This is a flowchart showing the control procedure of the print control process.

[0043] Figure 7A This is a diagram illustrating an example of the amount of ink discharged when printing is performed by two scans.

[0044] Figure 7B This is a diagram illustrating an example of the amount of ink discharged when printing is performed by two scans.

[0045] Figure 8 This is a diagram illustrating a first modification of the amount of ink ejected when printing is performed by two scans.

[0046] Figure 9 This is a diagram illustrating a second modification of the amount of ink ejected when printing is performed by two scans.

[0047] Figure 10A This is a diagram illustrating a third modification of the amount of ink ejected when printing is performed by two scans.

[0048] Figure 10BThis is a diagram illustrating a third modification of the amount of ink ejected when printing is performed by two scans.

[0049] Figure 10C This is a diagram illustrating a third modification of the amount of ink ejected when printing is performed by two scans.

[0050] Figure 11A This is a diagram illustrating a fourth modification of the amount of ink ejected when printing is performed by two scans.

[0051] Figure 11B This is a diagram illustrating a fourth modification of the amount of ink ejected when printing is performed by two scans.

[0052] Figure 11C This is a diagram illustrating a fourth modification of the amount of ink ejected when printing is performed by two scans.

[0053] Figure 12A : is a diagram showing an example of a driving waveform.

[0054] Figure 12B : is a diagram showing an example of a driving waveform.

[0055] Figure 12C : is a diagram showing an example of a driving waveform. DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0057] Figure 1A 1 is a front view illustrating a schematic structure of an inkjet recording device 1 according to an embodiment of the present invention. Figure 1B It is a plan view of the inkjet recording apparatus 1 .

[0058] The inkjet recording apparatus 1 includes an inkjet head 20 (discharge operation unit), a UV irradiation unit 42 , a scanning unit 121 , a scanning guide unit 122 , a conveyance stage 131 , a conveyance guide unit 132 , and the like.

[0059] The object of ink discharge in the inkjet recording device 1 of this embodiment is, for example, a wiring substrate S (substrate). The wiring substrate S is placed on a conveying table 131. The conveying table 131 can move in the direction (conveying direction, sub-scanning direction) along the conveying guide portion 132 such as a guide rail when the wiring substrate S is placed thereon. The wiring substrate S has a roughly flat conductor (wiring conductor) constituting a signal wiring on an insulating substrate. The conductor is not particularly limited, but may be, for example, copper (copper foil). The signal wiring is located protrudingly on the surface of the insulating substrate, so the wiring substrate S has a stepped portion. In addition, the landed ink does not penetrate into the interior of the wiring substrate S, but bulges on the surface to solidify and fix. In addition, here, the insulating substrate surface is a plane, and the perpendicular outer direction relative to the plane is set to the top.

[0060] The inkjet head 20 has nozzles N (see Figure 2 ), ink is discharged from the nozzle N to the wiring substrate S. The amount of ink discharged to each pixel range in each ink discharge cycle can be selected from a plurality of stages. The UV irradiation unit 42 irradiates ultraviolet light (UV light) to the wiring substrate S on which the ink has landed. The inkjet head 20 and the UV irradiation unit 42 are fixed to the scanning unit 121, and move (scan) in a direction along the scanning guide 122 (scanning direction. That is, a direction intersecting with the moving direction of the conveyor table 131, which is an orthogonal direction here). Their movement can be achieved using, for example, a linear motor or the like. The nozzles of the inkjet head 20 are arranged across the width of the wiring substrate S, and the arrangement interval of the nozzles can be set small enough to complete printing (single pass) with one scan. In addition, multi-pass (interlaced) ink discharge can be performed by repeatedly scanning the inkjet head 20 multiple times while moving the wiring substrate S.

[0061] Figure 2 It is a block diagram showing the functional configuration of the inkjet recording apparatus 1 .

[0062] The inkjet recording device 1 includes a transport unit 10, an inkjet head 20 (ink ejection unit), a head drive control unit 30, a fixing unit 40, a control unit 50, a storage unit 60, an ink heating unit 70, a display unit 81, an operation receiving unit 82, and a communication unit 90. The control unit 50 is communicatively connected to each unit via a bus or the like.

[0063] The transport unit 10 moves the inkjet head 20 relative to the medium on which the image (cover film) is to be formed, in this case, the wiring substrate S. As described above, for example, the inkjet head 20 can move in a predetermined direction (scanning direction) relative to the wiring substrate S, and the wiring substrate S can move in a direction perpendicular to the scanning direction of the inkjet head 20.

[0064] The transport unit 10 includes a scanning drive unit 12 and a transport drive unit 13. The scanning drive unit 12 performs scanning by moving the inkjet head 20 on the scanning unit 121. The scanning drive unit 12 includes, for example, a linear motor, and moves the inkjet head 20 directly or indirectly via a fixing member of the inkjet head 20.

[0065] The transport drive unit 13 moves a placing member such as a base (transport stage 131 ) or a conveyor belt on which the wiring substrate S is placed. The transport drive unit 13 can reciprocate the placing member.

[0066] The inkjet head 20 includes a head drive unit 22 and a plurality of nozzles N. Ink is ejected from each nozzle N in response to a drive signal output by the head drive unit 22. The head drive unit 22 includes, for example, an ejection selection IC 28 (Integrated Circuit) and an electromechanical transducer element 223. The ejection selection IC 28 switches based on image data so that a drive signal corresponding to the presence or absence of ink ejection from each nozzle N and the amount of ink ejected is output to the electromechanical transducer element 223 corresponding to each nozzle N. The electromechanical transducer element 223 is, for example, a piezoelectric element, and changes shape in response to the input drive signal. This shape change causes pressure fluctuations in the ink within the ink flow path connected to the nozzle N.

[0067] The electromechanical conversion element 223 and the nozzle N constitute the recording element 26 .

[0068] The head drive control unit 30 includes a head control unit 31 and a drive waveform signal generating circuit 32, etc. Based on the output data (digital data) of the drive waveform signal generating circuit 32, the drive waveform signal (analog signal) related to the discharge of ink, etc. is output to the inkjet head 20 at a predetermined time period (ink discharge period). The drive waveform signal related to the discharge of ink can also be a combination of multiple pulse signals. In addition, it is also possible to output a drive waveform signal with multiple types of different waveform patterns (not only waveforms, but also changes in pulse length, amplitude, voltage value, etc.) according to the amount of ink discharged. Alternatively, it is also possible to output a number of continuous drive pulses corresponding to the amount of ink droplets per pixel (multi-pulse method). In this case, the ink droplets discharged by each drive pulse are merged in flight, or landed within the same pixel range. The amount of ink discharged from each nozzle to each pixel in each pass (cycle) is determined to achieve the minimum thickness of the insulating film (e.g., 15 μm) described later, taking into account the surface characteristics of the wiring substrate S, the temperature (viscosity characteristics) of the ink during discharge, and the time interval from the landing of the ink droplets to their temporary fixing by UV light irradiation from the UV irradiation unit 42. Furthermore, it is possible to output a non-discharge waveform pattern for agitating the ink within the nozzle N, in addition to the discharge of ink.

[0069] In addition to or in lieu of the aforementioned methods, other methods can be used to control the ink discharge volume (landing amount) per pixel. For example, the state of the ink surface (meniscus) within the nozzle N can be adjusted by adjusting the ink pressure (normally, to a negative pressure to prevent ink leakage) when no drive pulses are applied, or by varying the drive frequency. Furthermore, the ink droplet volume can be adjusted by applying drive pulses of a suitable non-discharge waveform pattern before the ink discharge waveform pattern, thereby vibrating the meniscus and applying drive pulses of a drive waveform pattern.

[0070] The ink discharged by the inkjet recording device 1 of this embodiment is, for example, solder resist ink. Solder resist ink is discharged onto the wiring substrate S to form an insulating film (solder resist) thereon. Solder resist ink cures upon exposure to predetermined energy rays, in this case, ultraviolet (UV) light. Furthermore, solder resist ink is thermosetting.

[0071] The solder resist ink contains a compound having a thermosetting functional group. As the thermosetting functional group, various known functional groups can also be used, for example, a functional group having an isocyanate group (particularly two or more) can be cited. In addition, from the perspective of improving high temperature and high humidity resistance and improving the storage properties of the ink, it is preferred to protect the isocyanate group with a polyfunctional isocyanate compound (blocked isocyanate) by a thermally dissociable blocking agent. The thermally dissociable blocking agent is not particularly limited, but for example, is a compound comprising at least one of an oxime compound, a pyrazole compound, and an active vinyl compound.

[0072] Alternatively, the thermosetting functional group may be a (meth)acrylate group, particularly a (meth)acrylate compound having an imide group, such as imide acrylate. The imide group has a high polarity, resulting in strong adhesion to metal (i.e., the wiring on the wiring substrate S). Furthermore, due to its strong cohesive force, adhesion to metal is minimally affected even in high humidity.

[0073] On the other hand, as a component of the solder resist ink related to curing based on UV light irradiation, the ink contains a compound having a photopolymerizable functional group and a photopolymerization initiator. The photopolymerizable compound is a variety of compounds that have the function of polymerizing by irradiation with active energy rays (UV light) or crosslinking by crosslinking reaction, thereby curing the ink. For example, free radical polymerizable compounds or cationic polymerizable compounds can be listed. The polymerizable compounds having an imide group such as the above-mentioned imide acrylate also have UV curability. The photopolymerization initiator is an initiator corresponding to the above-mentioned type of photopolymerizable functional group (compound).

[0074] The solder resist ink also contains a gelling agent. The ink is in a gel state at room temperature, but undergoes a phase transition between a gel state and a sol state depending on the temperature, causing a dramatic change in viscosity. The gelling agent can be, for example, at least one of the compounds represented by the following general formulas (G1) or (G2).

[0075] General formula (G1): R1-CO-R2

[0076] General formula (G2): R3-COO-R4

[0077] In these formulas, R1 to R4 each independently represent a linear moiety having 12 or more carbon atoms, and may also have a branched alkyl chain. Such a gelling agent can be dispersed in the cured film without hindering the curing properties of the ink. This improves the moisture resistance of the printed ink film (solder resist), preventing moisture from penetrating into the cured film. Furthermore, this improves insulation reliability. Furthermore, inks containing this gelling agent have good pinning properties, making it easier to form a cover film that balances thin lines and film thickness (i.e., excellent thin line reproducibility even when film thickness is required).

[0078] The fixing unit 40 performs the action of fixing the ink landed on the wiring substrate S. As mentioned above, the ink has thermosetting properties and curing properties based on active energy lines (UV light), so correspondingly, the fixing unit 40 has a UV irradiation unit 42 and a heating fixing unit 43. Although not particularly limited, here the UV irradiation unit 42 is fixed to the scanning unit 121 together with the inkjet head 20 as mentioned above to perform scanning, so that the ink landed on the wiring substrate S is temporarily fixed. The UV irradiation unit 42, for example, has a light-emitting diode (LED) that generates ultraviolet rays, and by applying a voltage to the LED so that current flows through it, it emits light and irradiates ultraviolet rays (UV light). The UV irradiation unit 42 may also have a light-shielding wall or the like for blocking the leakage of UV light outside the desired irradiation range as needed.

[0079] Furthermore, the UV irradiation unit 42 is not limited to an LED for generating UV light. For example, the UV irradiation unit 42 may include a mercury lamp. Furthermore, if the ink has the property of being cured by active energy rays other than UV light, the UV irradiation unit 42 may include a known emission source (light source) that generates active energy rays that cure the ink, instead of the aforementioned UV light-generating unit.

[0080] The heating and fixing section 43 has a heating section such as an infrared heater or an electric heating wire heater, which directly or indirectly heats the wiring substrate S so that the temporarily fixed ink is formally fixed. After the ink is deposited and temporarily fixed by the inkjet head 20 and the UV irradiation section 42, the heating and fixing section 43 transports the wiring substrate S to the downstream side in the conveying direction so that it is located at a position for formal fixing. The heating and fixing section 43 can also be located in a housing that surrounds the wiring substrate S and a portion of the conveying component that carries the wiring substrate, so that the heat generated by the heating section is retained inside the housing and efficiently maintained at an appropriate curing temperature. In this case, it is not necessary to keep the heating section in operation during heating, and it is sufficient to maintain the temperature within a set range related to the above-mentioned curing temperature.

[0081] Alternatively, the heating and fixing unit 43 may be provided in a separate heating and fixing device, rather than in the inkjet recording apparatus 1. The heating and fixing device is a post-processing device of the inkjet recording apparatus 1. The wiring substrate S may be directly fed to the heating and fixing device via the transport unit 10, for example, in an extension of the moving direction of the transport table 131. Alternatively, the wiring substrate S removed from the transport table 131 of the inkjet recording apparatus 1 may be reset to the heating and fixing device, or the wiring substrate S may be manually moved by a user.

[0082] The control unit 50 centrally controls the operations of various components of the inkjet recording device 1. The control unit 50 includes a CPU 51 (Central Processing Unit) and a RAM 52 (Random Access Memory). The CPU 51 is a hardware processor that performs various calculations and executes programs 61 stored in the storage unit 60. The RAM 52 provides memory space for the CPU 51 to control the system and stores temporary data.

[0083] The storage unit 60 includes at least a non-volatile memory that stores a program 61 and setting data. As a non-volatile memory, for example, a flash memory can be cited. In addition, an HDD (Hard Disk Drive) or the like can also be included in the non-volatile memory mentioned here. In addition, the storage unit 60 may also include a RAM for temporarily storing image data 62 representing the formation (coverage) range of the covering film to be formed, and driving data for the inkjet head 20 generated based on the data. The program 61 includes a control program related to the ink discharge control process and the coverage range adjustment process described later. The setting data includes thickness corresponding information 63 containing information related to the ink discharge amount corresponding to the thickness of the covering film to be formed. Although the resolution of the information on the coverage range (setting range) shown in the image data 62 is not particularly limited, it can be, for example, above 1440 dpi (dot per inch).

[0084] The ink heating unit 70 heats the ink in the inkjet head 20 and the ink supply path to the inkjet head 20 to maintain it at an appropriate temperature. As mentioned above, the ink undergoes a phase change between sol and gel depending on the temperature, so the fluidity of the ink is insufficient when it is kept in a gel state at room temperature, making it difficult to supply and discharge the ink. The ink heating unit 70 heats the ink to an appropriate temperature to keep the ink in a sol state, thereby enabling supply and appropriate discharge. The appropriate temperature is defined as the time at which the ink rapidly releases heat due to the wiring substrate S after it lands on the wiring substrate S and gels at an appropriate time. The ink heating unit 70 includes, for example, a heating wire and a thin sheet member (rubber, etc.) heated by the heat generated by the heating wire. The thin sheet member contacts the ink supply path, etc. and transfers heat to heat the ink.

[0085] The display unit 81 displays various statuses, menus, and the like on a display screen under the control of the control unit 50. The display unit 81 includes, for example, a display screen and LED (Light Emitting Diode) lamps. The display screen is not particularly limited, but an example is an LCD (Liquid Crystal Display). The LED lamps are illuminated (including flashing) in positions and colors corresponding to the power supply status, abnormality occurrence, and other conditions, for example, by the control unit 50.

[0086] The operation receiving unit 82 receives input operations from an external user, etc., and outputs them as input signals to the control unit 50. The operation receiving unit 82 includes, for example, a touch panel and push buttons. The touch panel may overlap the display screen of the display unit 81. Alternatively, the operation receiving unit 82 may include various other operation switches.

[0087] The communication unit 90 controls the transmission and reception of data (signals) with external devices, etc., according to a predetermined communication standard. For example, the communication unit 90 controls communications according to LAN (Local Area Network) standards. Alternatively, the communication unit 90 may be capable of connecting to peripheral devices, etc., according to USB (Universal Serial Bus) standards.

[0088] Next, a printing operation in the inkjet recording apparatus 1 of this embodiment will be described.

[0089] In the inkjet recording device 1, during scanning, ink is discharged from the inkjet head 20 onto pixels on a particular scan line (including those rows if multiple rows of nozzles N are arranged in the scanning direction) during each ink discharge cycle. The scan drive unit 12 then moves the inkjet head 20 so that the nozzles N face pixels on other scan lines. When performing multiple passes of ink discharge, scanning is performed while changing the positional relationship between the wiring substrate S on the transport stage 131 and the nozzles N (the pixels on the scan line to be ink-discharged) during each pass. UV irradiation is performed by the UV irradiation unit 42 for each scan.

[0090] Figure 3A as well as Figure 3B This is a diagram illustrating the printing range of the wiring substrate S.

[0091] Solder resist ink is used to form an insulating film I (solder resist) on the wiring substrate S. The insulating film I defines a printing range (i.e., a coverage range) in the wiring substrate S according to the signal wiring C on the insulating substrate R, and is stored as image data 62. The insulating film I includes openings and cutouts such as circular, annular, square, and thin lines, depending on the range of the connection pads P for connecting the signal wiring C located on the insulating substrate R to the electronic components, external signal lines, etc. The thickness of the insulating film I is not particularly limited, but is, for example, in the range of 15 to 30 μm.

[0092] like Figure 3B As shown, the surface of the insulating film I has irregularities depending on the presence or absence of signal wiring C on the wiring substrate S. In the stepped portions of the irregularities, landed ink tends to flow toward the concave portion before solidifying. As a result, if the ink is simply discharged uniformly, no ink may remain near the end (shoulder Es) of the upper portion of the stepped portion (on the convex side), resulting in interrupted printing and exposure of the signal wiring C, thus failing to provide insulation.

[0093] In the inkjet recording device 1 of this embodiment, during scanning (in at least any one pass in the case of multiple passes), the ink discharge amount (the amount of ink droplets discharged and landed at each pixel position) of at least any one of the step portion, the flat portion on the lower side connected to the step portion, and the flat portion on the upper side is increased compared to the ink discharge amount to other flat portions.

[0094] exist Figure 4 2 shows an example of the distribution of the discharge amounts of three types of ink.

[0095] Generally speaking, the side of the signal wiring C does not stand completely perpendicular to the insulating substrate R, but has several inclined areas E (inclined portions). A lower connecting portion LC (lower adjacent portion) of a specified width in the insulating substrate R adjacent to the inclined area E and an upper connecting portion UC (upper adjacent portion) of a specified width in the signal wiring C adjacent to the inclined area E (i.e., forming the inclined area E at both ends) are specified, and the ink discharge amount (the amount of discharged ink droplets) to at least any selected area of these inclined areas E, the lower connecting portion LC, and the upper connecting portion UC (collectively referred to as three stepped areas (three areas)) is specified to be greater (increased) than the ink discharge amount (the amount of discharged ink droplets) to the remaining flat portion LF of the insulating substrate R and the flat portion UF in the center of the signal wiring C (outside the three areas). In addition, the inclined area E is not limited to a flat surface and can also be a curved surface, etc., and can also have unevenness relative to the average inclined surface. The width of the inclined area E is not particularly limited, but is usually narrower than the height to the extent that it can be said to be a step. Similarly, the prescribed widths of the upper connecting portion UC and the lower connecting portion LC are not particularly limited, as long as they are approximately one pixel. For example, the prescribed widths of the upper connecting portion UC and the lower connecting portion LC may also be the diameter of the landing range of ink droplets landing on the flat portions UF and LF (the larger (increased) discharge volume of the multiple stages of ink discharge volume may be used as a reference). Although this is not particularly limited, in general, it is often the same as the width of a single pixel (e.g., 10.6 μm at 2400 dpi) or approximately 1 to 15 times larger. (If the landing ranges of the flat portions UF and LF differ depending on the material, either one may be used as a reference, or the average value may be used as a reference.) That is, the prescribed widths of the upper connecting portion UC and the lower connecting portion LC may also be the landing range of ink connected to ink droplets landing on the inclined region E, and / or the extent to which at least a portion of the landing range reliably includes ink droplets that span the inclined region E. Alternatively, the upper connection portion UC and the lower connection portion LC may have different widths (the width of the upper connection portion UC may be determined based on the range of contact with the flat portion UF, while the width of the lower connection portion LC may be determined based on the range of contact with the flat portion LF). Furthermore, if the wiring width is narrow or the wiring spacing is narrow, portions without the flat portion UF or the flat portion LF may be provided depending on the situation.

[0096] In the example shown in pattern A, the amount of ink discharged only to the inclined area E is greater than the amount of ink discharged to other parts. In the example shown in pattern B, in addition to the inclined area E, the amount of ink discharged from the upper connecting portion UC is also increased. On the contrary, in the example shown in pattern C, in addition to the inclined area E, the amount of ink discharged from the lower connecting portion LC is increased. At this time, as for the increase in the amount of ink discharged, it is also possible to include different increases between the areas where the amount of ink discharged increases in the three areas of the step. Here, the increase in the inclined area E is greater than the increase in the lower connecting portion LC. In addition, it is also possible to independently specify the increase in the amount of ink discharged in the three areas of the step as different (uneven) ink discharge amounts.

[0097] Figures 5A to 5C It is a diagram explaining the increase in the ink discharge amount.

[0098] The size of each of the three step regions and the area to be increased in the amount of ink discharged can also be determined based on the material and surface characteristics of the wiring substrate S. For example, by discharging more ink to the area with higher wettability, ink shortage caused by flow-down can be suppressed. Figure 5A As shown, when the wettability of the insulating substrate R is higher than that of the signal wiring C, more ink is discharged toward the inclined region E and the lower connection portion LC. The sizes of the three circles represent the amounts of ink discharged directly downward.

[0099] like Figure 5B As shown, when the wettability of the insulating substrate R is lower than that of the signal wiring C, more ink can be discharged to the inclined area E and the upper connecting portion UC. Figure 5C As shown, in the case where both the insulating substrate R and the signal wiring C are made of materials with low wettability (for example, the wettability can be determined by comparing the spread size of the landed ink with a reference size), it is also possible to increase the amount of ink discharged only into the inclined region E. In this case, since the effect of ink droplets being stretched and expanded by merging with ink landed nearby may be greater than the spread characteristics of ink droplets on the wiring substrate S, it is also possible to prevent ink droplets landed in the inclined region E from being stretched to the sides by not increasing the amount of ink discharged into the upper connecting portion UC and the lower connecting portion LC.

[0100] In addition, in reality, there are many cases where the boundaries of each pixel do not exactly coincide with the boundaries of the three areas of the step, and a portion of the ink droplets land across multiple areas. In such a case, for example, the corresponding area can be determined simply based on the landing center position (center of gravity position, etc., and the flow caused by tilt, etc. can also be ignored), or the discharge amount can be calculated and adjusted based on the proportion of multiple areas and the ink discharge amount for each area. In addition, the width (prescribed width) of the upper connecting portion UC and the lower connecting portion LC can be a fixed width, or it can be determined based on the characteristics (material) of the expansion of the ink in each area, the size (height) of the step, etc. In addition, the width of the upper connecting portion UC and the lower connecting portion LC can also be different.

[0101] Figure 6 This is a flowchart showing the control procedure of the CPU 51 (control unit 50) in the print control process of this embodiment. The print control process starts when a print command is acquired from an external device or the like along with image data indicating a coverage area (the timing of data acquisition and command acquisition may differ).

[0102] When the print control process starts, the CPU 51 (control unit 50) acquires (step S101) the wiring pattern data of the wiring board S. The CPU 51 specifies the edge of the wiring, that is, the step portion, based on the wiring pattern data (step S102).

[0103] The CPU 51 obtains image data representing the printing (ink discharge) range (step S103). The CPU 51 increases the ink discharge amount for at least one of the three step areas according to predetermined conditions for the portion of the image data that overlaps with the edge position (step S104).

[0104] The CPU 51 adjusts the position of the wiring substrate S based on the image data (step S105). For example, adjustment can be made by specifying an offset value, rotation amount, etc. relative to the normal placement position of the wiring substrate S. This adjustment can be performed automatically by the CPU 51 or through manual operation (input operation, etc.) by the user. The CPU 51 causes the inkjet head 20 to discharge ink based on the modified image data, thereby printing the cover film (insulating film I) (step S106).

[0105] The CPU 51 activates the UV irradiation unit 42 to irradiate the wiring substrate S with UV light, temporarily curing the ink on the wiring substrate S (step S107). The CPU 51 heats the wiring substrate S to cure and fix the cover film (insulating film I) (step S108). The CPU 51 then terminates the print control process.

[0106] Regarding the above-mentioned action, the case of single-pass printing has been described, but in the case of multi-pass printing, ink discharge is performed based on multiple scans, for example, two scans, at equal intervals and complementarily. In the case of more than three scans, the phases are staggered at equal intervals in each scan and the ink is discharged. Alternatively, the pattern involved in the position and sequence of the multi-pass ink discharge can also be based on other methods. However, in the inkjet recording device 1 (printing method) of this embodiment, each pixel is not scanned multiple times by controlling the ink discharge a number of times corresponding to the ink discharge amount. That is, a scan is not performed that selectively discharges ink only before and / or after the position that increases the ink discharge amount, and uniform ink discharge control is not performed in the remaining scans. In other words, in at least any one scan, the ink discharge amount is different depending on the setting of the ink droplet amount for each pixel (except for the presence or absence of ink discharge).

[0107] Figure 7A as well as Figure 7B This is a diagram illustrating an example of the amount of ink discharged when printing is performed by two scans (two passes).

[0108] exist Figure 7A , an example is shown in which the amount of ink discharged is increased in the lower connecting portion LC in each of the first and second strokes.

[0109] exist Figure 7B The ink discharge amount (landing amount) at each pixel position is schematically shown. In fact, the ink landing range is larger than the pixel range, but for the sake of explanation, the normal ink discharge amount landing range is made consistent with the pixel range, and the pixels with increased ink discharge amount are shown as circles larger than the pixel range. Figure 7B For example, ink discharge begins with the top row of pixels (horizontally arranged) and moves row by row toward the next row during each discharge cycle as the pixels are scanned. Furthermore, in the example shown here where the shoulder extends in a direction parallel to the scanning direction, the nozzles with increased ink discharge remain fixed during the scan. However, if the shoulder extends in a direction not parallel to the scanning direction, the nozzles with increased ink discharge move sequentially according to the scanning position.

[0110] By combining the discharges in the two passes in this manner, it is possible to obtain a continuous distribution in which the amount of ink discharged into the lower connecting portion LC is greater than the amount of ink discharged into other portions.

[0111] Figure 8 This is a diagram illustrating a first modification of the amount of ink ejected when printing is performed by two scans (two passes).

[0112] Here, the ink discharge volume into the lower connecting portion LC and the inclined region E is set to be greater than that into other regions through two passes of ink discharge. In this case, the timing is controlled so that during the first scan (pass 1), only the ink discharge volume into the lower connecting portion LC is increased, while during the second scan (pass 2), increased ink discharge into the inclined region E is performed. By initially supplying more ink to the lower connecting portion LC and temporarily solidifying it, the ink discharged onto the inclined surface during the second scan can be prevented from easily spreading toward the side of the lower connecting portion LC.

[0113] As mentioned above, when the scanning direction is not parallel to the extension direction of the shoulder, it is difficult to completely make the discharge order consistent. However, in cases where the three areas of the step each have a width of multiple pixels, or when all pixels cannot be discharged in the same amount due to the expansion of the above-mentioned ink droplets and the upper limit of the discharge amount per unit area of the wiring substrate S, it can also be set to discharge pixels that selectively increase the ink discharge amount as much as possible in the order mentioned above.

[0114] Figure 9 This is a diagram showing a second modification of the amount of ink ejected when printing is performed by two scans.

[0115] In this figure, the ink discharge rate from the lower connection LC and upper connection UC is increased through two ink discharge strokes. In this case, the increased ink discharge to both the lower connection LC and upper connection UC occurs in the first stroke. In situations where the slope of the inclined region E is steep (nearly vertical) or the wettability of the conductor surface is high, increasing the ink discharge rate to the lower connection LC and upper connection UC may more reliably prevent the appearance of the shoulder than increasing the ink discharge rate to the inclined region E itself.

[0116] In this example, the ink discharge amount is made uniform during the second scan, that is, it is sufficient that the ink discharge distribution is different at least once in a plurality of scans.

[0117] Figures 10A to 10C This is a diagram showing a third modification of the amount of ink ejected when printing is performed by two scans.

[0118] In order to more flexibly and easily adjust the ink discharge amount to the three areas of the step, the ink discharge amount to each area is not fixed separately, but the ink discharge amount corresponding to the proportion can be obtained as an average by combining multiple types of ink discharge amounts.

[0119] exist Figure 10A In this example of the ink discharge amount distribution, as Figure 10B as well as Figure 10CAs shown, during the first scan, large ink droplets and small (normal) ink droplets are alternately discharged at each point in the upper connecting portion UC and the lower connecting portion LC. On average, these upper connecting portion UC and the lower connecting portion LC are given a droplet volume intermediate between large and small droplets. By appropriately adjusting the ratio of large to small droplets within a range that does not cause uneven ink discharge, the average droplet volume can be varied. This eliminates the need to meticulously control the ink discharge waveform pattern to achieve three or more levels of ink discharge volume.

[0120] Figures 11A to 11C This is a diagram showing a fourth modification of the amount of ink ejected when printing is performed by two scans.

[0121] In getting Figure 11A In the case of the distribution of ink discharge amount shown in Figure 11B As shown in FIG, in the first scan, large ink droplets are discharged for each pixel in the lower connecting portion LC, so that the amount of droplets applied is increased on average compared to normal. Figure 11C As shown, in the second scan, large ink droplets and small ink droplets are alternately discharged for each pixel in the inclined area E, and on average, the inclined area E is given a droplet amount intermediate between the normal ink discharge amount and the large ink droplet discharge amount.

[0122] In addition, here, the timing of ejecting large ink droplets in the two scans is equal, that is, Figure 11B as well as Figure 11C In the second scan, the odd-numbered ink droplets from the top are large ink droplets. However, this is not limited to this. It can also be stipulated that the timing is alternating, for example, in the second scan, the even-numbered ink droplets from the top are large ink droplets.

[0123] The combination of ink discharges of multiple droplet amounts shown in Modifications 3 and 4 is not limited to multi-pass ink discharge. In a single-pass ink discharge, multiple droplet amounts can be similarly combined to evenly distribute the droplet amounts in between. Furthermore, the positional setting of the droplet sizes can be achieved through various other appropriate timing settings. For example, the size of each droplet can be randomly determined probabilistically, or the timing of droplet size can be dispersed through dithering or the like.

[0124] Figures 12A to 12C : is a diagram showing an example of a driving waveform.

[0125] For example, relative to Figure 12A The amount of ink droplets discharged by the waveform shown in Figure 12B In the driving waveform of , the amount of ink droplets discharged becomes smaller. Figure 12CIn the driving waveform pattern of the multi-drop method shown, by reducing a part of the five consecutive pulses that can be output at maximum during the ink discharge cycle, for example, reducing a specified number from the front end, the amount of ink droplets corresponding to the number of pulses can be adjusted to merge (or not merge) during flight and land on the same pixel position.

[0126] As described above, the printing method of the inkjet recording device 1 of this embodiment is a printing method that discharges ink onto a wiring substrate S having a stepped portion. The stepped portion includes three regions: an inclined region E forming the step, an upper connecting portion UC of a predetermined width adjacent to the inclined region E, and a lower connecting portion LC of a predetermined width adjacent to the inclined region E. The method includes a discharge volume setting step for increasing the amount of ink droplets discharged per ink discharge cycle for at least one selected region among these three regions compared to the amount of ink droplets discharged for the other regions. The ink droplet volume referred to here is the average discharge volume for each region and is not limited to increasing the discharge volume for all pixels.

[0127] By increasing the amount of ink droplets discharged near the inclined area E compared to normal, even if the ink slightly spreads on the landing surface (wiring substrate S), the possibility of ink covering the inclined area E, particularly the upper corner (shoulder Es), disappearing and becoming exposed can be reduced. This allows for more reliable printing on a printing surface with steps, that is, the ink landing area on the printing medium surface can be more reliably covered with ink.

[0128] In addition, the discharged ink contains a gelling agent, which makes the ink that has landed on the landing surface into a gel state and quickly adheres to the landing surface, thereby suppressing the wetting and spreading along the landing surface and enabling more accurate printing.

[0129] Furthermore, the distribution of the ink droplet amount in the selected area is uneven. In addition to the ink flowing down in steps, the ink spreads differently depending on the material of the wiring board S, the characteristics of the ink, and so on. Therefore, by adjusting the distribution of the ink droplet amount based on these factors, this printing method can more reliably perform printing with less unevenness.

[0130] Furthermore, the selected area includes at least two of the three areas, and the ink droplet amounts for each of the at least two areas include different amounts. Alternatively, the ink droplet amount distribution can be specified for each of the three areas of the step. Even if the ink droplet amounts for each of the three areas of the step are set based on differences between flat and inclined portions, or differences in the materials of the respective portions, appropriate printing results can be easily and reliably achieved without causing printing omissions that would unnecessarily expose the wiring substrate S.

[0131] Furthermore, the selected area is determined by the material of the wiring substrate S. As described above, the spreading pattern (wettability) is determined by the combination of the wiring substrate S material and the ink characteristics. Therefore, by increasing the amount of discharged ink within an appropriate range based on the material of the wiring substrate S, ink coverage omissions can be avoided, resulting in more accurate printing.

[0132] Furthermore, the wiring substrate S includes an insulating substrate R and signal wiring C located on the insulating substrate R, and the ink is solder resist ink. Specifically, during the printing operation to form an insulating film on the wiring substrate S using the solder resist ink, by increasing the ink discharge amount in the stepped portion as described above, insulation properties due to the cover film can be more reliably achieved.

[0133] In addition, the ink is cured by irradiation with a predetermined energy line. By utilizing the energy line irradiation to rapidly cure and fix the ink landed on the wiring substrate S, and in particular to temporarily fix it, it is possible to suppress the ink from flowing down on the step and achieve a state of covering the desired range.

[0134] Furthermore, the energy rays are defined as ultraviolet rays. By irradiating the ink landing surface with ultraviolet rays at appropriate timing, the ink can be cured in a desired state according to the timing.

[0135] The ink may also be thermosetting, thereby preventing the ink from becoming solubilized and losing its shape or flowing due to temperature changes after fixing.

[0136] The inkjet recording apparatus 1 of the present embodiment includes an inkjet head 20 for discharging ink and a control unit 50. When discharging ink for printing onto a wiring substrate S having a stepped portion including three regions: an inclined region E constituting a step, an upper connecting portion UC of a predetermined width adjacent to the inclined region E, and a lower connecting portion LC of a predetermined width adjacent to the inclined region E, the control unit 50 (CPU 51) increases the amount of ink droplets per ink discharge cycle discharged in at least one selected region among the three regions compared to the amount of ink droplets discharged in the regions other than the three regions.

[0137] By performing such ink discharge control in the inkjet recording apparatus 1, even if ink slightly spreads on the landing surface (wiring substrate S), the possibility of ink covering the inclined area E, particularly the upper corner (shoulder Es), disappearing and becoming exposed can be reduced. This allows for more reliable printing on a printing surface with steps.

[0138] In addition, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made.

[0139] For example, in the above embodiment, the ink discharge rates are set separately or uniformly for the three regions of the step, but the ink discharge rates may also vary within each region. For example, the ink discharge rate may be set to decrease gradually from the upper connecting portion UC toward the upper flat portion UF, gradually approaching the normal ink discharge rate in the flat portion UF before connecting.

[0140] Furthermore, regarding the inclined region E, the ink discharge amount may be increased only in a portion thereof, such as the upper half.

[0141] In addition, in the above embodiment, both the inkjet head 20 and the conveyor table 131 can be moved, but in the case of single-pass printing, as long as either one, such as the conveyor table 131, can be moved, the inkjet head 20 can also be fixed.

[0142] Furthermore, in the above embodiment, the ink containing the gelling agent is described as an example. However, the ink does not need to contain a gelling agent in particular, and may be an ink whose viscosity can be highly changed by temperature changes or the like.

[0143] In addition, in the above embodiment, the discharge of ink having both UV curing properties and thermal curing properties is described as an example, but it can also be ink having only one of the two properties, or it can be ink that is cured by irradiation with energy rays other than UV light.

[0144] In addition, in the above embodiment, the case of printing and forming an insulating film on the wiring substrate S is described, but the present invention is not limited to this. For example, a protective film or the like can be printed and formed on other substrates with steps (mainly substrates with no ink penetration or low ink penetration, such as resin parts, films, etc.). It is not limited to a cover film. The above technology can also be applied to lines, graphics, patterns, etc. formed on the substrate to suppress the occurrence of image quality or structural abnormalities such as interruptions in the stepped portion. In these cases, the film thickness (ink discharge amount) can be appropriately changed according to the application, etc.

[0145] In addition, the specific configurations, contents and sequences of the processing operations described in the above embodiments can be modified as appropriate without departing from the spirit of the present invention. The scope of the present invention includes the scope of the invention described in the claims and their equivalents.

[0146] Industrial applicability

[0147] The present invention can be utilized in a printing method and an inkjet recording apparatus.

[0148] Explanation of reference numerals: 1… inkjet recording device, 10… conveying unit, 12… scanning drive unit, 121… scanning unit, 122… scanning guide unit, 13… conveying drive unit, 131… conveying table, 132… conveying guide unit, 20… inkjet head, 22… head driving unit, 223… electromechanical conversion element, 26… recording element, 28… discharge selection IC, 30… head driving control unit, 31… head control unit, 32… driving waveform signal generating circuit, 40… fixing unit , 42…UV irradiation unit, 43…heating and fixing unit, 50…control unit, 60…storage unit, 61…program, 62…image data, 63…thickness corresponding information, 70…ink heating unit, 81…display unit, 82…operation receiving unit, 90…communication unit, C…signal wiring, E…inclined area, Es…shoulder, I…insulating film, LC…lower section connection part, N…nozzle, P…connecting pad, R…insulating substrate, S…wiring substrate, UC…upper section connection part.

Claims

1. A printing method comprising discharging ink onto a substrate having a stepped portion, wherein: The step portion includes three areas: an inclined portion constituting a step, an upper adjacent portion of a predetermined width adjacent to the inclined portion, and a lower adjacent portion of a predetermined width adjacent to the inclined portion. The printing method includes a discharge amount setting step, wherein the amount of ink droplets discharged per ink discharge cycle for at least any one selected area among the three areas is increased compared to the amount of ink droplets discharged for areas other than the three areas. The base material is a wiring substrate including an insulating substrate and wiring conductors located on the insulating substrate. The above ink is solder resist ink, The solder resist ink contains a compound having a thermosetting functional group.

2. The printing method according to claim 1, wherein: The above ink contains a gelling agent.

3. The printing method according to claim 1 or 2, wherein: The distribution of the ink droplet amount in the selected area is non-uniform.

4. The printing method according to claim 3, wherein: The selected area includes at least two of the three areas mentioned above. The ink droplet amounts for each of the at least two regions include mutually different ink droplet amounts.

5. The printing method according to any one of claims 1 to 4, wherein: The selected area is determined according to the material of the substrate.

6. The printing method according to any one of claims 1 to 5, wherein: The ink is cured by irradiation with predetermined energy rays.

7. The printing method according to claim 6, wherein: The above-mentioned prescribed energy rays are ultraviolet rays.

8. The printing method according to any one of claims 1 to 7, wherein: The above ink is thermosetting.

9. An inkjet recording device, wherein: have: a discharge action portion for discharging ink; and Control Department, When printing is performed by ejecting ink onto a substrate having a stepped portion having three regions including an inclined portion constituting a step, an upper adjacent portion of a predetermined width adjacent to the inclined portion, and a lower adjacent portion of a predetermined width adjacent to the inclined portion, The control unit increases the amount of ink droplets discharged per ink discharge cycle to at least any one selected area among the three areas compared to the amount of ink droplets discharged to areas other than the three areas. The base material is a wiring substrate including an insulating substrate and wiring conductors located on the insulating substrate. The above ink is solder resist ink, The solder resist ink contains a compound having a thermosetting functional group.

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