Printing operation with improved template separation

Abstract

After the printing operation, the separation between the printing screen or stencil and the at least one single workpiece is controlled by selectively vertically driving the surround. In particular, an upward force can be applied to the surround after printing, before and / or during separation. A drive means is also provided to control the movement of the surround, which can conveniently be placed between the surround and the conveying unit.

Description

Technical Field

[0001] This invention relates to a printing press for printing printing media onto a single workpiece fixed within a carrier, and a method for printing printing media onto a single workpiece. Background Technology

[0002] Industrial screen printing machines typically apply conductive printing media, such as solder paste or conductive ink, onto planar workpieces (like circuit boards) by using beveled blades or squeegees carried by the print head to pass the conductive printing medium through a pattern of holes in a printing screen (sometimes called a foil or stencil). When the pattern area is relatively small compared to the screen area, the screen can contain multiple patterns, allowing multiple circuit boards to be printed simultaneously using the same screen.

[0003] This can be achieved by pre-separating or "single-processing" individual circuit boards before the printing process. In this process, any defective circuit boards can be identified and immediately discarded before printing, ensuring that only defect-free boards are printed. While this process is relatively efficient, it also introduces some complexities. Supporting and calibrating the relatively small individual circuit boards is particularly difficult when simultaneous (or continuous) printing is required.

[0004] To address these issues, various methods have been developed. For example, GB2484373A describes a method for individually positioning each circuit board, but this method only allows printing one substrate at a time. JP-2009-248551 describes a method in which the position of each circuit board is checked individually, and each circuit board is repositioned sequentially using a repositioning arm. While this technique can print all circuit boards on a panel simultaneously, it requires additional equipment (i.e., the positioning arm), and moving the positioning arm between workpieces is very time-consuming. WO2014 / 166956 describes an alternative device in which all circuit boards are supported on their respective "towers" and can be simultaneously aligned using a reference strip, followed by synchronous printing. This solution works well, but it is unsuitable if incoming unprinted circuit boards are positioned too far off-center.

[0005] EP3693168A1 describes a workpiece support assembly that is capable of supporting and individually aligning multiple relatively small workpieces (often referred to as "single" workpieces). Figure 2An example of such a component 4 is schematically shown, comprising a 2 x 4 array of individually supported "towers" 5. Each tower 5 has a support surface 6 on top, which can be used to support the workpiece (not shown) during the printing operation. Furthermore, each tower 5 can be independently actuated to move in the orthogonal directions X and Y (typically in the horizontal plane) and rotate about the orthogonal Z-axis (typically extending in the vertical direction), thus achieving so-called θ-angle correction. Such movement can be advantageously achieved by employing a parallel motion actuation system within each tower, as described in EP3693168A1. Of course, the array size can also be larger or smaller. This system, published by ASMPT and named "MASS," provides a very fast and accurate printing solution.

[0006] During the printing process, if individual workpieces are supported by a tower, these individual workpieces are loaded into the printing press in a carrier, which is a tray with an open container on which each individual workpiece can be placed, while the tower can pass through the tray to contact the underside of each workpiece.

[0007] Figure 1 The immediate state of this known system after the carrier 12 has been fed into the printing press is shown schematically from the side. In this example, the carrier 12 can accommodate eight individual workpieces W in a 2x4 array. Figure 1 Only four of these single workpieces W can be seen at a time. The carrier 12 is transported by a conveyor unit 5, which includes two conveyor belts (sometimes called "tracks") on which the two sides of the carrier 12 are mounted. Figure 1 For clarity, the conveyor belt itself is not shown in the figure, but it can be understood that in practical applications, the conveyor belt can be mounted on the inwardly projecting "wall" of the support carrier 12 shown in the figure. The conveying unit 5 is supported by rigid blocks 6, which are securely fixed to the printing press. As detailed below, the conveying unit 5 can move upward away from the rigid blocks 6. The conveying unit 5 also supports a side panel 7, which comprises a flat plate with a plurality of openings 8 formed therein, each opening 8 being sized to accommodate a single workpiece W during use. The side panel 7 is positioned below the printing screen 9, which, as previously described, has a pattern of holes corresponding to the locations on the single workpiece W where the printing medium needs to be deposited. During use, the printing medium can be evenly distributed through the holes by passing the printing head 10 with a squeegee 11 across the upper surface of the printing screen 9.

[0008] To initiate the printing operation, the conveying unit 5 transports the carrier 12 until it is positioned above the tooling device. In this case, the tooling device comprises multiple tool turrets 2, one for each workpiece W, extending upwards from a tool base 14, which provides electrical and / or pneumatic connections to each turret 2. The tool base 14 is supported on a tool table 1. Each turret 2 has a support surface 3 at its upper end for supporting the corresponding workpiece W during use, as described in more detail below. The tool table 1 can be driven vertically (i.e., parallel to the vertical axis or "Z" axis) by a table drive (not shown). The vertical movement of the tool table 1 naturally results in a corresponding vertical movement of each turret 2. Also schematically shown in the figure are abutment members 4 associated with the tool table 1, arranged to abut the conveying unit 5, as described below.

[0009] Next, as Figure 2 As shown, the workbench 1 is lifted upwards. The tower 2 passes through the open container in the carrier 12 and lifts each individual workpiece W from the carrier 12 and feeds it into the opening 8 of the enclosure 7, at which point the top of the enclosure 7 is flush with or slightly lower than the top of the workpiece W. At this height, the moving abutment member 4 is brought into contact with the conveying unit 5.

[0010] Then, as Figure 3 As shown, the workbench 1 continues to move upward. The tower 2 continues to move the workpiece W upward, and due to the reaction force of the abutment member 4 on the conveying unit 5, the conveying unit 5 and the side plate 7 are also lifted upward at the same speed as the workpiece W. The workpiece W continues to be lifted upward until it reaches its printing height, at which point the workpiece W is pressed into the underside of the printing screen 9, as is the side plate 7. As the squeegee 11 passes over the printing screen 9, the side plate 7 and the workpiece W together provide a substantially flat surface for the squeegee 11 to prevent the squeegee from "bounced". The printing medium 13 introduced into the upper surface of the printing screen 9 is spread into the holes of the printing screen 9, and thus onto the upper surface of the single workpiece W.

[0011] After printing, as follows Figure 4 As illustrated, the worktable 1 descends, simultaneously lowering the tower 2, conveyor unit 5, and enclosure 7, thereby separating the printed workpiece W from the printing screen 9. As the worktable 1 continues to descend, the printed workpiece W is returned to the carrier 12. Once the tower 2 is removed from the carrier 12, the carrier 12 can be transported away and removed from the printing press to be replaced by a new carrier (not shown) containing unprinted workpieces. This process can then be repeated until the current total number of prints is completed.

[0012] However, a problem exists: due to the relatively low mass of a single workpiece W, the separation of workpiece W from the printing screen 9 may be relatively abrupt or violent, which can adversely affect the printed deposits on workpiece W. During separation, the central portion of the printing screen 9 changes from being rested in a relatively large area (i.e., the total area of ​​the surrounding plates 7, which can be relatively large compared to the size of a single workpiece W) to being completely unsupported. This, in turn, can cause the printing screen 9 to "wobble," meaning that the tension on the printing screen 9 will change, and this, combined with the change in the coplanarity of the screen and the workpiece, may adversely affect the printed deposits during separation.

[0013] The present invention aims to solve this problem. In particular, the present invention aims to achieve controllable separation between the printing screen and the workpiece.

[0014] According to the present invention, this objective is achieved by controlling separation using a retaining plate. In particular, an upward force can be applied to the retaining plate after printing, before separation, and / or during separation. Summary of the Invention

[0015] According to a first aspect of the present invention, a printing press is provided for printing a printing medium onto a single workpiece fixed within a carrier, the printing press comprising: A tooling device that is vertically movable within the printing press, wherein the tooling device includes a support surface for supporting the single workpiece thereon; A conveying device for positioning the carrier above the tooling device, so that a single workpiece fixed in the carrier is positioned above the support surface; A panel including an opening sized to receive the single workpiece and the carrier during use, the panel being positioned above the tooling device; The printing press includes a drive unit that is mechanically engaged with the enclosure and operable to drive the enclosure vertically upward relative to the tooling device.

[0016] According to a second aspect of the present invention, a method for printing a printing medium onto a single workpiece is provided, the method comprising the following steps: i) Place the single workpiece into the carrier; ii) Conveying the carrier into a printing press, the printing press comprising: A tooling device, vertically movable within the printing press, wherein the tooling device includes a support surface for supporting the single workpiece thereon; and A panel, including an opening sized to receive the single workpiece during use, the panel being positioned above the tool; iii) Position the carrier above the tool device, thereby positioning the single workpiece above the support surface; iv) Lift the tool device so that the support surface contacts the single workpiece, then lift the single workpiece from the carrier and place it into the opening of the enclosure; v) Depositing printing media onto the single workpiece by spreading printing media on the upper surface of a printing screen located above the single workpiece; and vi) Separating the single workpiece from the printing screen by lowering the tooling device; Step vi) includes lifting the enclosure relative to the tool device.

[0017] Other specific aspects and features of the invention are set forth in the appended claims. Attached Figure Description

[0018] The invention will now be described with reference to the accompanying drawings (not drawn to scale), in which: Figures 1 to 4 The steps of a known printing process using standard printing equipment are schematically shown from the side. Figures 5 to 9 The steps of the printing process according to an embodiment of the present invention are schematically shown from the side; and Figure 10 The enclosure and drive mechanism according to an embodiment of the present invention are shown schematically from above.

[0019] Explanation of reference numerals in the attached figures: 1 - Tool Table 2 - Tool Tower 3—Support Surface 4 - Abutment Components 5 - Transmission Unit 6 - Hard stop 7 - Enclosure 8 - Opening 9—Printing screen 10 - Printing Head 11 - Scraper 12—Carrier 13 - Printing Media 14 - Tool Base 15—Drive Unit 15A, 15B, 15C – Actuators W – Workpiece. Detailed Implementation

[0020] Examples of embodiments of the present invention Figures 5 to 9 As shown. This device is related to... Figures 1 to 4The devices shown have many similarities, so reference numerals will be retained where possible.

[0021] Figure 5 and Figure 1 Similarly, a highly schematic side view shows the immediate state of the system after the carrier 12 is fed into the printing press. In this example, the carrier 12 can accommodate eight individual workpieces W in a 2x4 array. Figure 5 Only four of these single workpieces W can be seen at a time. The carrier 12 is transported by a conveying device. This conveying device includes a conveying unit 5, which comprises two conveyor belts (sometimes called "tracks") on which the two sides of the carrier 12 are mounted. Figure 5 For clarity, the conveyor belt itself is not shown in the figure, but it will be understood that in practical applications, the conveyor belt can be mounted on the inwardly projecting "wall" of the support carrier 12 shown in the figure. The conveying unit 5 is supported by rigid blocks 6, which are securely fixed to the printing press. As detailed below, the conveying unit 5 can move upward away from the rigid blocks 6. The conveying unit 5 also supports a side panel 7, which comprises a flat plate with a plurality of openings 8 formed therein, each opening 8 being sized to accommodate a single workpiece W in use. According to this embodiment, the printing press includes a drive unit 15 mechanically engaged with the side panel 7, in which case the side panel 7 is supported by the conveying unit 5 via the drive unit 15. The drive unit 15 includes at least one linear actuator operable to drive the side panel 7 perpendicularly (i.e., parallel to the vertical axis or "Z" axis) relative to the conveying unit 5 and the tooling device (i.e., the tower 2 and the tool base 14, as described below).

[0022] The baffle 7 is positioned below the printing screen 9, which, as previously described, has a pattern of holes corresponding to the locations on a single workpiece W where printing media needs to be deposited. In use, by moving the printing head 10 with a squeegee 11 across the upper surface of the printing screen 9, the printing media can be evenly distributed through the holes.

[0023] To initiate the printing operation, the conveying unit 5 transports the carrier 12 until it is positioned above the tooling device. In this case, the tooling device comprises multiple tool turrets 2, one for each workpiece W, extending upwards from a tool base 14, which provides electrical and / or pneumatic connections to each turret 2. The tool base 14 is supported on a tool table 1. Each turret 2 has a support surface 3 at its upper end for supporting the corresponding workpiece W during use, as described in more detail below. The tool table 1 can be driven vertically (i.e., parallel to the vertical axis or "Z" axis) by a table drive (not shown). The vertical movement of the tool table 1 naturally results in a corresponding vertical movement of each turret 2. Also schematically shown in the figure are abutment members 4 associated with the tool table 1, arranged to abut the conveying unit 5, as described below.

[0024] Next, as Figure 6 As shown, the workbench 1 is lifted upwards. The tower 2 passes through the open container in the carrier 12 and lifts each individual workpiece W from the carrier 12 and feeds it into the opening 8 of the enclosure 7, at which point the top of the enclosure 7 is flush with or slightly lower than the top of the workpiece W. At this height, the moving abutment member 4 is brought into contact with the conveying unit 5.

[0025] Then, as Figure 7 As shown, the workbench 1 continues to move upward. The tower 2 continues to move the workpiece W upward, and due to the reaction force of the abutment member 4 on the conveying unit 5, the conveying unit 5 and the side plate 7 are also lifted upward at the same speed as the workpiece W. The workpiece W continues to be lifted upward until it reaches its printing height, at which point the workpiece W is pressed into the underside of the printing screen 9, as is the side plate 7. As the squeegee 11 passes over the printing screen 9, the side plate 7 and the workpiece W together provide a substantially flat surface for the squeegee 11 to prevent the squeegee from "bounced". The printing medium 13 introduced into the upper surface of the printing screen 9 is spread into the holes of the printing screen 9, and thus onto the upper surface of the single workpiece W.

[0026] After printing, as follows Figure 8 As schematically shown, the drive unit 15 is actuated to lift the enclosure 7 relative to the conveying unit 5. Subsequently and / or simultaneously, as Figure 8 and Figure 9 As shown, the tool table 1 is lowered to further separate the printed workpiece W from the printing screen 9, and the conveying unit 5 is lowered to return the workpiece W to the carrier 12. The relative timing between the actuation of the drive device 15 and the lowering of the tool table 1 is flexible, and various examples will be described in more detail below.

[0027] The drive unit 15 is actuated to return the enclosure 7 to its initial position relative to the conveyor unit 5, and once the tower 2 is removed from the carrier 12, the carrier 12 with the printed workpiece W is conveyed away and removed from the printing press to replace it with a new carrier (not shown) with an unprinted workpiece fixed inside. This process can then be repeated until the current total number of prints is completed. As mentioned above, from Figure 7 The relative timing between the actuation of the drive unit 15 and the descent of the tool table 1, starting from the indicated printing position, is flexible. Exemplary solutions include: 1) Before lowering the workbench 1, lift the side panel 7. This presses the side panel 7 upwards into the printing screen 9 before the tower 2 descends. This method ensures controllable tension inside the printing screen 9 and minimizes the "wobbling" of the printing screen 9 during separation, while also being easy to control. 2) As the worktable 1 (and conveyor unit 5) descends, the sheath 7 is raised relative to the conveyor unit 5. This method helps to minimize stress on the printing screen 9. In a particularly preferred embodiment, the drive unit 15 drives the sheath 7 upward at the same speed as the worktable 1 descends, thereby maintaining the sheath 7 at a substantially constant absolute height during at least a portion of the worktable 1 descent. This method minimizes stress generated in the printing screen 9 and is also slightly faster than the method described in 1) above; or 3) Before or during lowering the worktable 1, lift the first portion of the retaining plate 7 relative to the second portion of the retaining plate 7. This allows the retaining plate 7 to rotate away from a purely horizontal orientation. This technique can be used to smoothly "peel" the printing screen 9 from the printing workpiece W, or to control the tension in the printing screen 9 at precise locations. In this example, different portions of the retaining plate 7 can be lifted depending on the distribution direction of the squeegee 11 on the upper surface of the printing screen 9. Typically, in continuous printing operations, the print head moves alternately in two opposing horizontal directions, i.e., back and forth on the printing screen 9. Therefore, adjusting the inclination of the retaining plate 7 relative to this distribution direction is advantageous.

[0028] Regarding option 3 above, the above text can be used. Figure 10 The schematically shown device achieves this attitude control of the enclosure 7. Here, openings 8 arranged in a 4x2 array on the enclosure are visible. The enclosure 7 shown is transparent, thus revealing the three actuators 15A, 15B, and 15C that collectively constitute the drive unit 15. These actuators 15A, 15B, and 15C engage with the enclosure 7 at horizontally spaced locations around it. Using three actuators 15A, 15B, and 15C spaced apart along the horizontal axis is the minimum configuration required to control the pitch and roll of the enclosure 7. However, an arrangement including at least one additional actuator can also be used.

[0029] The above embodiments are merely exemplary, and other feasible solutions and alternatives within the scope of the present invention will be readily apparent to those skilled in the art.

Claims

1. A printing press for printing printing media onto a single workpiece fixed within a carrier, comprising: A tooling device that can move vertically within the printing press, wherein the tooling device includes a support surface for supporting the single workpiece thereon; A conveying device for positioning the carrier above the tooling device, so that a single workpiece fixed in the carrier is positioned above the support surface; A panel including an opening sized to receive the single workpiece and the carrier during use, the panel being positioned above the tooling device; The printing press includes a drive unit that is mechanically engaged with the enclosure and operable to drive the enclosure vertically upward relative to the tooling device.

2. The printing press according to claim 1, comprising: A lifting platform that can move vertically, wherein the tool device is supported on the lifting platform to move vertically with the lifting platform.

3. The printing press according to claim 1, wherein, The enclosure is supported by the conveying device via a drive mechanism, enabling the enclosure to move relative to the conveying device in the vertical direction.

4. The printing press according to claim 1, wherein, The drive device includes at least three vertical actuators, each of which engages with the enclosure at horizontally spaced positions around the enclosure.

5. The printing press according to claim 4, wherein, The at least three vertical actuators can be driven independently.

6. A method for printing a printing medium onto a single workpiece, comprising the following steps: i) Place the single workpiece into the carrier; ii) Conveying the carrier into a printing press, the printing press comprising: A tooling device, vertically movable within the printing press, wherein the tooling device includes a support surface for supporting the single workpiece thereon; and A panel including an opening sized to receive the single workpiece during use, the panel being positioned above the tooling device; iii) Position the carrier above the tool device, thereby positioning the single workpiece above the support surface; iv) Lift the tool device so that the support surface contacts the single workpiece, then lift the single workpiece from the carrier and place it into the opening of the enclosure; v) Depositing printing media onto the single workpiece by spreading printing media on the upper surface of a printing screen located above the single workpiece; and vi) Separating the single workpiece from the printing screen by lowering the tooling device; Step vi) includes lifting the enclosure relative to the tool device.

7. The method according to claim 6, wherein, Step vi) includes lifting the guard plate relative to the printing screen before lowering the tooling device, so that the guard plate presses upward into the printing screen.

8. The method according to claim 6, wherein, Step vi) includes raising the enclosure relative to the tool device while lowering the tool device.

9. The method according to claim 8, wherein, Step vi) includes lifting the enclosure relative to the tool device, so that the enclosure is held at a constant height for at least a portion of the time in this step.

10. The method according to claim 6, wherein, Step vi) includes lifting a first portion of the enclosure relative to a second portion of the enclosure.

11. The method according to claim 10, wherein, Step v) includes moving a squeegee along the spreading direction on the upper surface of the printing screen and selecting a first portion of the enclosure according to the spreading direction, which includes one of two opposing horizontal directions.

12. The method according to claim 6, wherein, Step i) includes placing multiple individual workpieces into the carrier.

13. The method according to claim 12, wherein, Step v) includes depositing the printing medium onto the plurality of individual workpieces during a single dispersal of the printing medium onto the upper surface of the printing screen.

14. The method of claim 12, wherein, Step v) involves depositing printing media onto one of the plurality of individual workpieces, and the method further includes the following steps: vii) Move the carrier so that another single workpiece among the plurality of single workpieces is positioned above the support surface; then viii) Repeat steps iv) to vii) until each of the plurality of workpieces has a printing medium deposited on it.

15. The method according to claim 6, wherein, The printing press includes the printing press according to claim 1.

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