JP5548953B2 - Screen printing method - Google Patents

Description

  The present invention relates to a screen printing method by a screen printer that transfers a paste to a substrate through a mask.

  The screen printing machine includes a substrate holding unit that holds a substrate, a mask that is in contact with the upper surface of the substrate held by the substrate holding unit, a squeegee base that is provided above the mask, and a mask that is moved down with respect to the squeegee base. Supplied on the mask by moving the squeegee base in one direction in the horizontal plane (paste scraping direction) with the squeegee in contact with the upper surface of the mask. The paste is scraped with a squeegee to transfer the paste to the substrate.

  In such a screen printing machine, after the paste is transferred to the substrate, when the squeegee raised (separated) from the mask is lowered next to the mask when it is next brought into contact with the mask, the squeegee separated from the mask is used. Formed on the mask when the paste that was attached to and drooped to the back of the squeegee (the surface opposite the squeegee paste scraping surface) and then moved (slided) on the mask. In some cases, the paste is caught at the corners (hole edges) of the mask holes to form protrusions protruding upward, so-called paste cornering occurs. Such cornering of the paste remains on the electrode of the substrate even after the plate is separated from the substrate to cause printing defects.

  Conventionally, as a technique for preventing the cornering of the paste, when the squeegee is lowered and brought into contact with the upper surface of the mask, the squeegee base is moved in the horizontal direction opposite to the paste scraping direction at the same time as the squeegee starts to descend. It is known that the squeegee is brought into contact with the upper surface of the mask obliquely by moving the lens to (see, for example, Patent Document 1). As a result, the paste that is attached to the squeegee and hangs down around the front surface (paste scraping surface) of the squeegee, thereby preventing the cornering of the paste from occurring.

Japanese Patent No. 3989065

  However, conventionally, when the actuator for raising and lowering the squeegee is a cylinder, the cylinder has poor operation responsiveness at the start of operation (responsiveness to the operation command signal output from the control device). Therefore, the lowering operation is delayed, and thus the lowering operation is completed with a delay from the timing when the horizontal movement of the squeegee base driven by the electric motor with good operation response is completed. For this reason, the squeegee does not move in an oblique orbit in which the squeegee descending operation and the squeegee base moving operation in the horizontal direction are synchronized in the entire descending process from the start of descent to the end of descent, and initially moves obliquely downward. However, after the movement of the squeegee base in the horizontal direction is completed, the squeegee base has moved along a trajectory that descends perpendicularly to the mask. For this reason, the paste that has adhered to the squeegee and hangs down does not wrap around the back of the squeegee, and it is impossible to sufficiently prevent the occurrence of cornering of the paste.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a screen printing method in which the squeegee is in contact with the mask at an angle so as to reliably prevent the occurrence of cornering of the paste.

  The screen printing method according to claim 1, comprising: a substrate holding unit that holds a substrate; a mask that is in contact with an upper surface of the substrate held by the substrate holding unit; a squeegee base provided above the mask; and a squeegee base. And a squeegee that is lowered by a cylinder provided on the upper surface of the mask and abutted against the upper surface of the mask, with the squeegee being in contact with the upper surface of the mask, the squeegee base in one direction in the horizontal plane. A screen printing method using a screen printing machine that moves the paste supplied onto the mask with a squeegee to transfer the paste to the substrate by moving the squeegee while lowering the squeegee relative to the squeegee base. When detecting that the squeegee has been lowered, and detecting that the squeegee has been lowered by a predetermined amount, Moving the squeegee base in a horizontal direction opposite to the paste scraping direction for a predetermined time without stopping the descent of the squeegee with respect to the squeegee base; and moving the squeegee base in a horizontal direction opposite to the paste scraping direction for a predetermined time A step of stopping the squeegee descending and the horizontal movement of the squeegee base when the squeegee contacts the upper surface of the mask, and scraping the paste with the squeegee base in contact with the upper surface of the mask. And moving the paste in the direction and scraping the paste supplied to the upper surface of the mask with a squeegee to transfer the paste to the substrate.

  In the present invention, the squeegee base is not moved in the horizontal direction immediately after the start of the squeegee descent with poor cylinder operation responsiveness, but the squeegee is lowered by a predetermined amount with respect to the squeegee base and the cylinder responsiveness is stabilized. Thus, the movement of the squeegee base in the horizontal direction is started while continuing the descent of the squeegee with respect to the squeegee base. For this reason, the squeegee moves on an oblique track that synchronizes the squeegee lowering movement and the horizontal movement movement of the squeegee base, and comes into contact with the mask. Therefore, it is possible to reliably prevent the occurrence of cornering of the paste.

The top view of the screen printer in one embodiment of the present invention The front view of the screen printer in one embodiment of the present invention The side view of the screen printer in one embodiment of the present invention The top view of the mask holder with which the screen printing machine in one embodiment of this invention is equipped, and a mask The block diagram which shows the control system of the screen printer in one embodiment of this invention (A) (b) (c) Enlarged front view of a mask and a squeegee included in a screen printing machine according to an embodiment of the present invention. The flowchart of the main routine which shows the flow of the screen printing process which the screen printer in one embodiment of this invention performs The flowchart of the subroutine which shows the flow of the screen printing process which the screen printer in one embodiment of this invention performs (A) (b) (c) Operation explanatory diagram of the screen printing machine when the screen printing machine in one embodiment of the present invention executes a screen printing operation (A) (b) (c) Operation explanatory diagram of the screen printing machine when the screen printing machine in one embodiment of the present invention executes a screen printing operation (A) (b) Operation | movement explanatory drawing of a screen printer when the screen printer in one embodiment of this invention performs screen printing work (A) (b) (c) Operation explanatory diagram of the screen printing machine when the screen printing machine in one embodiment of the present invention executes a screen printing operation (A) (b) (c) The figure which shows the positional relationship of a squeegee and a paste in the process in which the screen printer in one embodiment of this invention abuts a squeegee on a mask. The graph which shows the output state of the operation command signal with respect to the descent | fall operation | movement of a squeegee and the horizontal movement operation | movement of a squeegee base in the process in which the screen printing machine in one embodiment of this invention contact | abuts a squeegee. The figure which shows the movement locus | trajectory of the squeegee in the process in which the screen printer in one embodiment of this invention abuts a squeegee on a mask. (A) (b) Operation | movement explanatory drawing of a screen printer when the screen printer in one embodiment of this invention performs screen printing work (A) (b) (c) Operation explanatory diagram of the screen printing machine when the screen printing machine in one embodiment of the present invention executes a screen printing operation

  Embodiments of the present invention will be described below with reference to the drawings. The screen printing machine 1 shown in FIGS. 1, 2 and 3 carries in and positions a substrate 2 loaded from the outside, and pastes Pst (such as solder paste or conductive paste) on the electrodes 3 on the surface of the substrate 2. The operation of performing screen printing for transferring the image (see FIG. 3) and carrying it out to the outside is continuously executed, and a component mounting line is formed together with a component mounting machine, an inspection machine, etc. (not shown). Hereinafter, for convenience of explanation, the conveyance direction of the substrate 2 in the screen printing machine 1 is the X axis direction (left and right direction in FIG. 1), and the horizontal plane direction orthogonal to the X axis direction is the Y axis direction (up and down direction in FIG. 1). And the vertical direction is the Z-axis direction. The Y-axis direction is the front-rear direction of the screen printing machine 1 and the X-axis direction is the horizontal (left-right) direction of the screen printing machine 1. Further, in the front-rear direction, the operator OP (FIG. 1) of the screen printing machine 1 performs the operation on the screen printing machine 1 (below the paper surface in FIG. 1) is the front side of the screen printing machine 1, and the opposite side (see FIG. 1). 1) is the rear side of the screen printer 1.

  1, 2, and 3, the screen printing machine 1 has a substrate holding / moving unit 12 on a base 11, and a plate-like mask made of a metal thin plate material above the substrate holding / moving unit 12. 13. A pair of front and rear squeegees 14 and a camera unit 15 are provided.

  2 and 3, the substrate holding and moving unit 12 includes a horizontal moving unit 21, an elevating unit 22, a conveyor unit 23, a substrate supporting unit 24, and a substrate clamping unit 25.

  2 and 3, the horizontal moving unit 21 moves to the Y table 21a that moves in the Y-axis direction with respect to the base 11 by the operation of the Y table drive motor My, and to the Y table 21a by the operation of the X table drive motor Mx. The X table 21b that moves in the X axis direction, the θ table 21c that rotates around the Z axis with respect to the X table 21b, the base table 21d that is fixed to the upper surface of the θ table 21c, and the upper surface of the base table 21d that extends upward It consists of a plurality of lift table guides 21e provided.

  2 and 3, the elevating unit 22 is provided to extend upward from the upper surface of the elevating table 22a and the elevating table 22a which are guided by a plurality of elevating table guides 21e of the horizontal moving unit 21 and elevate with respect to the base table 21d. And a plurality of support unit lifting guides 22b.

  2 and 3, the conveyor unit 23 is attached to the upper end of the lower support unit elevating guide 22b, and a pair of front and rear belt conveyor supporting members 23a that elevate with respect to the base table 21d together with the elevating table 22a, and each belt conveyor supporting member. A pair of front and rear belt conveyors 23b supported by 23a is provided, and the front and rear belt conveyors 23b are operated in synchronization to carry the substrate 2 in the X-axis direction.

  2 and 3, the substrate support portion 24 is provided below the conveyor portion 23 on the upper surface of the lower support unit support table 24a and the lower support unit support table 24a which are guided by the lower support unit lifting guide 22b. The lower receiving unit 24b is provided with a plurality of lower receiving pins 24c extending upward. The substrate support unit 24 is configured such that the lower support unit 24b moves up and down with respect to the lift table 22a together with the lower support unit support table 24a, and a plurality of the lower support pins 24c are supported on the lower surface of the substrate 2 supported at both ends by the front and rear belt conveyors 23b. The substrate 2 is supported from below by making contact.

  2 and 3, the substrate clamp portion 25 is a pair of front and rear clamp members 25a provided on the upper portions of the front and rear belt conveyor support members 23a provided in the conveyor portion 23 so as to be movable in the Y-axis direction (see also FIG. 1). ), Both ends of the substrate 2 supported by the front and rear belt conveyors 23b and the lower surface of the substrate 2 are supported by the lower receiving unit 24b. .

  In FIG. 1 and FIG. 2, a substrate carry-in conveyor 26 comprising a pair of front and rear belt conveyors 26 a is provided on the upstream side of the conveyor unit 23 constituting the substrate holding and moving unit 12, and the downstream side of the conveyor unit 23 is A substrate carry-out conveyor 27 comprising a pair of belt conveyors 27a is provided. The substrate carry-in conveyor 26 carries in the substrate 2 input from the outside of the screen printing machine 1 and delivers it to the conveyor unit 23 of the substrate holding and moving unit 12. The substrate carry-out conveyor 27 is transferred from the conveyor unit 23 of the substrate holding and moving unit 12. The delivered substrate 2 is carried out of the screen printer 1. As described above, the substrate carry-in conveyor 26, the conveyor unit 23 of the substrate holding and moving unit 12 and the substrate carry-out conveyor 27 function as a substrate carrying path 28 (FIG. 1) for carrying the substrate 2.

  In FIG. 1 and FIG. 2, a pair of portal frames 31 are provided on the base 11 so as to straddle the substrate carry-in conveyor 26 and the substrate carry-out conveyor 27 in the Y-axis direction. The holder 32 is supported. The mask holder 32 has a pair of front and rear guide members 33 that are attached to the gate-shaped frame 31 and extend in the X-axis direction above the substrate holding and moving unit 12, and a pair of guide members 33 on the Y-axis direction. And a pair of left and right mask support rails 34 extending in the direction. The mask 13 is held in a horizontal position above the substrate holding and moving unit 12 by being supported at both left and right by a pair of left and right mask support rails 34 provided in the mask holder 32 (see also FIG. 4).

  In FIG. 1 and FIG. 4, the mask 13 is supported by a mask frame 13w made of a rectangular frame-like member in plan view, and a rectangular region surrounded by the mask frame 13w has a plurality of areas on the substrate 2. A large number of pattern holes 13 a corresponding to the electrodes 3 are provided. That is, the mask 13 has a large number of pattern holes 13 a formed according to the arrangement of the electrodes 3 on the substrate 2.

  In FIG. 1, two sets of substrate-side positioning marks mk are provided at diagonal positions of the substrate 2. On the other hand, in FIG. 4, the mask 13 is provided with a pair of mask side positioning marks MK arranged corresponding to the substrate side positioning marks mk. When the substrate 2 is brought into contact with the mask 13 with the substrate-side positioning mark mk and the mask-side positioning mark MK aligned vertically, the electrode 3 of the substrate 2 and the pattern hole 13a of the mask 13 are aligned vertically. Become.

  1 and 2, both ends of an X-axis stage 35 extending in the X-axis direction are supported by a pair of portal frames 31 so as to be slidable in the Y-axis direction. A camera support stage 36 is provided on the X-axis stage 35 so as to be movable in the X-axis direction. The camera unit 15 is attached to the camera support stage 36. The camera unit 15 includes a first camera 15a whose imaging field is directed downward and a second camera 15b whose imaging field is directed upward (FIG. 3).

  1 and 2, a pair of portal frames 31 support both ends of a squeegee base 37 extending in the X-axis direction, and the squeegee base 37 can reciprocate in the Y-axis direction along the portal frame 31. It has become.

  2 and 3, two squeegee raising / lowering cylinders 38 are provided at positions facing the Y-axis direction at the center of the upper surface of the squeegee base 37. From these two squeegee raising / lowering cylinders 38, a squeegee raising / lowering shaft 38a comprising a piston rod extends through the squeegee base 37 in the vertical direction and extends downward.

  A squeegee holder 39 extending in the X-axis direction is attached to the lower end of the squeegee lifting shaft 38 a provided in each squeegee lifting cylinder 38, and the squeegee 14 described above is held in each squeegee holder 39. Each squeegee 14 is formed of a “spar” -like member extending in the X-axis direction along the squeegee holder 39.

  When the squeegee lifting shaft 38a protrudes and retracts downward by each squeegee lifting cylinder 38, the squeegee 14 attached to the lower end of the squeegee lifting shaft 38a via the squeegee holder 39 moves up and down with respect to the squeegee base 37. Here, since the vertical distance between the mask 13 and the squeegee base 37 does not change, the squeegee 14 moves up and down with respect to the mask 13.

  Each operation of the substrate carry-in conveyor 26 as the substrate carrying path 28 for carrying the substrate 2, the conveyor unit 23 of the substrate holding and moving unit 12, and the substrate carry-out conveyor 27 includes an actuator (not shown) by the control device 40 (FIG. 5). This is done by controlling the operation of the substrate transport path operating mechanism 41 (FIG. 5).

  Actuation of the horizontal movement unit 21 of the substrate holding and moving unit 12 (movement of the Y table 21a in the Y-axis direction, movement of the X table 21b in the X-axis direction relative to the Y table 21a, and movement of the θ table 21c relative to the X table 21b (ie, the base In the rotation of the table 21d around the Z axis), the control device 40 controls the operation of the horizontal plane inward movement mechanism 42 (FIG. 5) including the actuator including the Y table drive motor My and the X table drive motor Mx described above. Is made by

  In the operation of the elevating unit 22 of the substrate holding and moving unit 12 (elevating and lowering the elevating table 22a with respect to the base table 21d), the control device 40 controls the operation of an up and down direction moving mechanism 43 (FIG. 5) including an actuator (not shown). Made by.

  The raising / lowering operation of the lower receiving unit 24b of the substrate holding / moving unit 12, that is, the raising / lowering operation of the lower receiving unit support table 24a with respect to the raising / lowering table 22a is performed by a lower unit 44 raising / lowering mechanism 44 (FIG. 5). This is done by performing the operation control.

  The clamping and releasing operation of the substrate 2 by the operation of the clamp unit 25 of the substrate holding and moving unit 12 (the opening and closing operation of the front and rear clamp members 25a) is performed by a clamp unit operating mechanism 45 (FIG. 5) including an actuator (not shown). ).

  The movement operation of the camera unit 15 in the horizontal plane (the movement operation of the X-axis stage 35 in the Y-axis direction with respect to the pair of portal frames 31 and the movement operation of the camera support stage 36 in the X-axis direction with respect to the X-axis stage 35) The controller 40 controls the operation of the camera unit moving mechanism 46 (FIG. 5) including an actuator (not shown).

  The operation control of the squeegee base 37 for reciprocating the front and rear squeegees 14 in the Y-axis direction is performed by the control device 40 controlling a squeegee base moving mechanism 47 (FIG. 5) including an actuator (not shown). Further, the raising / lowering operation of each squeegee 14 with respect to the squeegee base 37 is performed by the control device 40 controlling the operation of two squeegee raising / lowering cylinders 38 attached to the upper part of the squeegee base 37.

  The first camera 15 a constituting the camera unit 15 is controlled by the control device 40 to position the substrate 2 on the substrate side held by the substrate holding unit including the substrate support unit 24 and the substrate clamp unit 25 of the substrate holding and moving unit 12. The second mark 15k is picked up, and the second camera 15b is controlled by the control device 40 to pick up the mask side positioning mark MK provided on the mask 13. Both the image data obtained by imaging with the first camera 15a and the image data obtained by imaging with the second camera 15b are input to the control device 40 (FIG. 5).

  6A, 6 </ b> B, and 6 </ b> C, the squeegee base 37 reaches two lowering amounts for detecting that the lowering amount of each squeegee 14 with respect to the squeegee base 37 has reached a predetermined amount. A detection sensor 48 (FIG. 5) is provided. Each descending amount arrival detection sensor 48 is integrated with the squeegee 14 in the process in which the corresponding squeegee 14 descends with respect to the squeegee base 37 (FIG. 6A → FIG. 6B → FIG. 6C). When the projection 39a provided on the squeegee holder 39 that moves up and down relative to the squeegee base 37 is lowered by a predetermined amount SL below the squeegee base 37 (FIG. 6B), the projection 39a is detected and the control device is detected. A detection signal is output to 40.

  Here, the predetermined amount SL is controlled when, for example, the movement of the squeegee 14 is started by operating the squeegee raising / lowering cylinder 38 from a state where the squeegee 14 is positioned at the lowering start position of the squeegee 14 with respect to the squeegee base 37. It is set as a time exceeding the time until the operation responsiveness of the squeegee elevating cylinder 38 with respect to the operation command signal output from the device 40 becomes stable.

  The descending amount arrival detection sensor 48 may be a contact type sensor such as a limit switch, or may be a non-contact type sensor such as an optical sensor.

  Next, the execution procedure of the screen printing operation by the screen printer 1 will be described with reference to the flowcharts of FIGS. 7 and 8 and the explanatory diagrams of FIGS. Here, FIG. 7 is a flowchart of a main routine showing the flow of the screen printing process executed by the screen printer 1, and FIG. 8 is a flowchart of a subroutine of one process in the main routine.

  When screen printing work is performed by the screen printer 1 in the present embodiment, the control device 40 first displays the paste Pst on the operator OP by displaying an image via the display device 51 (FIG. 5) provided in the screen printer 1. Encourage supply. The operator OP visually checks the paste Pst remaining on the mask 13 and determines whether or not to supply (supplement) the paste Pst based on the amount of the paste Pst. When it is determined that the paste Pst should be supplied, the paste Pst is supplied onto the mask 13 by a separately prepared paste supply syringe (not shown), and when the supply of the paste Pst is finished, the screen printing is performed. The operation start button 52 (FIG. 5) provided in the machine 1 is operated. The operator OP operates the operation start button 52 even when it is determined that the supply of the paste Pst is unnecessary.

  When the control device 40 detects that the operation start button 52 has been operated by the operator OP, the control device 40 operates the substrate carry-in conveyor 26 and the conveyor unit 23 in conjunction with each other and is sent from another device installed on the upstream side of the screen printing machine 1. After the board 2 is carried into the screen printer 1, the board 2 is stopped at a predetermined work position on the conveyor unit 23 (FIG. 9A). The board carrying-in step of step ST1 shown in FIG.

  When the substrate carrying-in process in step ST1 is completed, the control device 40 closes the front and rear clamping members 25a to clamp the substrate 2 on the conveyor unit 23 from the Y-axis direction (FIG. 9B). Arrow A1) shown. Then, the lower receiving unit 24b is raised while the lifting table 22a is positioned at the lowered position with respect to the base table 21d (arrow B1 shown in FIG. 9C).

  The control device 40 raises the lower receiving unit 24b to bring the lower receiving pin 24c into contact with the lower surface of the central part of the substrate 2 from below to push the substrate 2 upward. The substrate 2 is moved upward while the both ends (both sides) of the substrate 2 are slid with respect to the front and rear clamp members 25a. And when the height of the upper surface of the board | substrate 2 becomes the same height as the upper surface of the clamp member 25a, the raise of the receiving unit 24b is stopped. As a result, the substrate 2 is held by the substrate holding portion (the substrate support portion 24 and the substrate clamp portion 25) (FIG. 9C). The substrate holding step of step ST2 shown in FIG.

  When the substrate holding process in step ST2 is completed, the control device 40 controls the operation of the camera unit moving mechanism 46, moves the X-axis stage 35 in the Y-axis direction, and moves the camera support stage 36 in the X-axis direction. Thus, the first camera 15a is positioned immediately above the substrate-side positioning mark mk provided on the substrate 2. Then, the first camera 15a is caused to pick up an image of the board-side positioning mark mk, and the image data is acquired to detect the position of the board 2 (FIG. 10A). Board position detection in step ST3 shown in FIG. Process). Further, the control device 40 positions the second camera 15b immediately below the mask-side positioning mark MK provided on the mask 13, and causes the second camera 15b to capture the mask-side positioning mark MK to obtain the image data. And the position of the mask 13 is detected (FIG. 10B) (mask position detection step of step ST4 shown in FIG. 7).

  When the mask position detection process in step ST4 is completed, the control device 40 controls the operation of the horizontal moving unit 21 included in the substrate holding and moving unit 12 and holds it by the substrate holding unit (the substrate support unit 24 and the substrate clamp unit 25). The substrate 2 is moved in the horizontal plane, and the substrate 2 is positioned in the horizontal plane with respect to the mask 13 so that the substrate-side positioning mark mk and the mask-side positioning mark MK face each other vertically (shown in FIG. 7). Positioning step of step ST5).

  When the positioning process of step ST5 is completed, the control device 40 raises the lifting table 22a relative to the base table 21d (arrow C1 shown in FIG. 10C), whereby the upper surface of the substrate 2 (printed surface). Is brought into contact with the lower surface of the mask 13 (FIG. 10C), the contacting step of step ST6 shown in FIG. As a result, the electrode 3 of the substrate 2 and the pattern hole 13a of the mask 13 are aligned vertically, and the substrate 2 is positioned at a position where the paste Pst is transferred by the squeegee 14.

  When the contact process of step ST6 is completed, the control device 40 lowers one of the two squeegees 14 and brings the lower end of the squeegee 14 into contact with the mask 13 in contact with the substrate 2 from above. (FIG. 11 (a) → FIG. 11 (b). Squeegee contact step in step ST7 shown in FIG. 7).

  At this time, the squeegee 14 to be brought into contact with the mask 13 is arranged such that the squeegee base 37 is positioned above the front clamp member 25a (FIG. 11A) (see FIG. 11A, FIG. 11A). When the squeegee 14 on the left side of the paper surface in (b) is located above the rear clamp member 25a, the rear squeegee 14 (the squeegee on the right side of the paper surface in FIGS. 11A and 11B). 14).

  Here, in the squeegee contact step of step ST7, as shown in the subroutine of FIG. 8, the control device 40 first controls the operation of the squeegee lifting cylinder 38 to start the lowering operation of the squeegee 14 (FIG. 8). Squeegee lowering step of step ST21 shown in Fig. 12 (a), (b), (c) and arrows D shown in Fig. 13 (a), (b). At this time, the squeegee lifting cylinder 38 that lifts and lowers the squeegee 14 is a squeegee lifting cylinder 38 coupled to the squeegee 14 that is to be brought into contact with the upper surface of the mask 13 (in FIG. 12 and FIG. Shows the case of lowering).

  FIG. 14 shows the output state of command signals for the lifting and lowering operations of the squeegee 14 and the horizontal movement operation of the squeegee base 37 when the screen printing machine 1 brings the squeegee 14 into contact with the mask 13. The output level (on / off) of the operation command signal output by the control device 40, and the horizontal axis is time. The time t0 shown in this figure is the time when the descending operation of the squeegee 14 is started.

  When the control device 40 starts the descent operation of the squeegee 14 in step ST21, the descent amount of the squeegee 14 currently descent with respect to the squeegee base 37 reaches the predetermined amount SL based on the output from the descent amount arrival detection sensor 48. This is detected (step of detecting the amount of descent in step ST22 shown in FIG. 8). Then, based on the output from the descending amount arrival detection sensor 48, the control device 40 detects that the descending amount of the squeegee 14 currently being lowered with respect to the squeegee base 37 has reached a predetermined amount SL (FIG. 12B). 14, the squeegee base 37 is moved in the horizontal direction opposite to the paste scraping direction while lowering the squeegee 14 relative to the squeegee base 37 (step ST23 shown in FIG. Horizontal movement process, arrow E shown in Fig. 12 (c) and Fig. 13 (a), 13 (b). Here, the front squeegee 14 scrapes the paste Pst from the upper surface of the front clamp member 25a to the upper surface of the rear clamp member 25a, and the rear squeegee 14 moves from the upper surface of the rear clamp member 25a to the upper surface of the front clamp member 25a. Since the paste Pst is scraped to the front, the paste scraping direction is the rear for the front squeegee 14 and the front for the rear squeegee 14.

  After starting to move the squeegee base 37 in the horizontal direction opposite to the paste scraping direction in step ST23, the control device 40 detects that a predetermined time DT (FIG. 14) has passed by a timer (not shown) (FIG. 8). In step ST24, a predetermined time elapse detection step), both the lowering operation of the squeegee 14 and the movement operation of the squeegee base 37 in the horizontal direction are stopped (movement stop step of step ST25 shown in FIG. 8). Time t2).

  Here, during the predetermined time DT, after the descending amount of the squeegee 14 with respect to the squeegee base 37 reaches the predetermined amount SL, the squeegee 14 and the squeegee base 37 are simultaneously moved (lowered or moved in the horizontal direction) at a predetermined speed, respectively. Sometimes, the time is set such that the lower end of the squeegee 14 is just in contact with the upper surface of the mask 13. For this reason, the control device 40 moves the squeegee base 37 in the horizontal direction opposite to the paste scraping direction while lowering the squeegee 14, and the squeegee 14 descends after a predetermined time DT has elapsed since the movement start of the squeegee base 37. When the movement operation of the squeegee base 37 is stopped together, the squeegee 14 moves closer to the mask 13 while moving in an oblique direction with respect to the mask 13 in the horizontal direction opposite to the paste scraping direction. Then, it comes into contact with the upper surface of the mask 13 as it is. FIG. 15 shows the movement trajectory P1 → P2 → P3 of the lower end of the squeegee 14 from when the squeegee 14 starts to move downward until it comes into contact with the upper surface of the mask 13.

  When the lower end of the squeegee 14 moves along the movement locus shown in FIG. 15 and abuts obliquely with respect to the upper surface of the mask 13, as shown in FIG. 13 and FIG. Even when the Pst is hanging, the suspended paste Pst can be wound around the front side of the squeegee 14 (paste scraping surface side, right side in FIG. 13 and FIG. 15) (FIG. 13A). ) → FIG. 13 (b) → FIG. 13 (c)). As shown in FIG. 15, when the squeegee 14 is brought into contact with the mask 13, when the squeegee 14 comes into contact with the mask 13, the paste Pst supplied on the mask 13 scrapes the paste of the squeegee 13. It is positioned in front of the surface in the traveling direction (right side of the drawing in FIG. 15).

  The control device 40 stops the squeegee 14 descending operation and the squeegee base 37 moving operation together to bring the squeegee 14 into contact with the upper surface of the mask 13 so that the squeegee 14 moves in the paste scraping direction. The base 37 is moved. Here, if the squeegee 14 in contact with the mask 13 is the front squeegee 14, the squeegee base 37 is moved backward (arrow F <b> 1 shown in FIG. 16A), and the squeegee 14 in contact with the mask 13. If is the rear squeegee 14, the squeegee base 37 is moved forward (arrow F2 shown in FIG. 16B).

  As a result, the squeegee 14 moves (slids) relative to the mask 13, and the paste Pst on the mask 13 is scraped by the paste scraping surface of the squeegee 14 and pushed into the pattern holes 13 a of the mask 13. The paste Pst is transferred onto the second electrode 3 (paste transfer step of step ST8 shown in FIG. 7).

  When the paste transfer process of step ST8 of the main routine is completed, the control device 40 raises the squeegee 14 and separates the squeegee 14 from the mask 13 (squeegee separation process of step ST9 shown in FIG. 7).

  When the squeegee separation step of step ST9 is completed, the control device 40 lowers the lifting table 22a with respect to the base table 21d (arrow C2 shown in FIG. 17A), and separates the substrate 2 from the mask 13 (FIG. 17 (a)). Thus, the plate separation is performed (the plate separation step in step ST10 shown in FIG. 7).

  When the plate separation process of step ST10 is completed, the control device 40 operates the clamp member 25a to release the clamp of the substrate 2 (arrow A2 shown in FIG. 17B), and then raises and lowers the lower receiving unit 24b. The table 22a is lowered (arrow B2 shown in FIG. 17C). Thereby, the board | substrate 2 is dropped on the conveyor part 23, and the holding | maintenance of the board | substrate 2 by a board | substrate holding part (the board | substrate support part 24 and the board | substrate clamp part 25) is cancelled | released (FIG.17 (c)) of step ST11 shown in FIG. Substrate holding release step).

  When the substrate holding release process of step ST11 is completed, the control device 40 operates the horizontal moving unit 21 included in the substrate holding and moving unit 12 to adjust the position of the conveyor unit 23 with respect to the substrate carry-out conveyor 27, and then the conveyor unit 23 and the substrate carry-out conveyor 27 are operated in an interlocked manner, the substrate 2 on the conveyor unit 23 is transferred to the substrate carry-out conveyor 27, and the substrate 2 is directly carried out of the screen printing machine 1 (the substrate carry-out process of step ST12 shown in FIG. 7). ).

  When the substrate carry-out process in step ST12 is completed, the control device 40 determines whether there is another substrate 2 to be screen-printed (substrate presence determination process in step ST13 shown in FIG. 7). As a result, if there is another substrate 2 to be screen-printed, the process returns to step ST1 to carry in a new substrate 2, and if there is no other substrate 2 to be screen-printed, a series of screen printing operations. Exit.

  As described above, the screen printing method according to the present embodiment is in contact with the substrate holding unit (substrate support unit 24 and substrate clamp unit 25) that holds the substrate 2 and the upper surface of the substrate 2 held by the substrate holding unit. And the squeegee base 37 provided above the mask 13 and the squeegee 14 lowered by the squeegee lifting cylinder 38 which is a cylinder provided on the squeegee base 37 and brought into contact with the upper surface of the mask 13. The squeegee 14 is moved in a paste scraping direction, which is one direction in the horizontal plane, with the squeegee 14 in contact with the upper surface of the mask 13, whereby the paste Pst supplied on the mask 13 is transferred to the squeegee 14. Is a screen printing method by the screen printing machine 1 that causes the paste Pst to be transferred to the substrate 2 by scraping While lowering the squeegee 14 with respect to the squeegee base 37, a step of detecting that the squeegee 14 has been lowered by a predetermined amount SL (step ST21 squeegee lowering step and step ST22 lowering amount arrival detecting step), and a squeegee 14 being a predetermined amount When it is detected that the SL has been lowered, the squeegee base 37 does not stop the squeegee 14 from being lowered with respect to the squeegee base 37, and the squeegee base 37 is not swung down with respect to the squeegee base 37 by the cylinder. A step of moving in the opposite horizontal direction for a predetermined time (DT) (step ST23 descending and horizontal movement step), and a squeegee base 37 is moved in the horizontal direction opposite to the paste scraping direction for a predetermined time (DT), and the squeegee 14 is moved. Where the ski touches the top surface of the mask 13 14 is stopped and the movement of the squeegee base 37 in the horizontal direction is stopped (movement stop process in step ST25), and the squeegee base 37 is moved in the paste scraping direction with the squeegee 14 in contact with the upper surface of the mask 13. This includes a process of moving the paste Pst supplied to the upper surface of the mask 13 with the squeegee 14 to transfer the paste Pst to the substrate 2 (paste transfer process of step ST8).

  In the screen printing method according to the present embodiment, the squeegee base 37 is not moved in the horizontal direction immediately after the squeegee 14 whose movement responsiveness of the squeegee raising / lowering cylinder 38 is not good is lowered. The movement of the squeegee base 37 in the horizontal direction is started while continuing the descent of the squeegee 14 with respect to the squeegee base 37 after the fixed amount SL is lowered and the operation responsiveness of the squeegee lifting cylinder 38 is stabilized. For this reason, the squeegee 14 moves along an oblique track in which the lowering operation of the squeegee 14 and the movement operation of the squeegee base in the horizontal direction are synchronized with each other and comes into contact with the mask 13. Since Pst can be made to wrap around the back of the squeegee 14, it is possible to reliably prevent the cornering of the paste Pst from occurring.

  Although the embodiments of the present invention have been described so far, the present invention is not limited to those shown in the above-described embodiments. For example, in the above-described embodiment, the lowering amount arrival detection sensor 48 detects the position of the protrusion 39a provided on the squeegee holder 39, but the squeegee is lowered by a predetermined amount SL relative to the squeegee base 37. As long as it is possible to detect the above, it is not always necessary to detect the position of the protrusion 39 a provided on the squeegee holder 39.

  Provided is a screen printing method capable of reliably preventing the occurrence of cornering of a paste by causing a squeegee to abut against a mask at an angle.

DESCRIPTION OF SYMBOLS 1 Screen printer 2 Board | substrate 13 Mask 14 Squeegee 24 Board | substrate support part (board | substrate holding part)
25 Substrate clamp (substrate holder)
37 Squeegee base 38 Squeegee lifting cylinder (cylinder)
Pst paste SL Predetermined amount

Claims (1)

A substrate holding unit that holds the substrate, a mask that is in contact with the upper surface of the substrate held by the substrate holding unit, a squeegee base that is provided above the mask, and a cylinder that is provided on the squeegee base. A squeegee that is in contact with the upper surface, and the squeegee is in contact with the upper surface of the mask, and the squeegee base is moved in the direction of scraping the paste, which is one direction in the horizontal plane. A screen printing method by a screen printing machine that scrapes the paste with a squeegee and transfers the paste to the substrate,
A step of detecting that the squeegee is lowered by a predetermined amount while lowering the squeegee with respect to the squeegee base;
A step of moving the squeegee base in a horizontal direction opposite to the paste scraping direction for a predetermined time without stopping the descent of the squeegee with respect to the squeegee base by the cylinder when it is detected that the squeegee has been lowered by a predetermined amount;
Moving the squeegee base in a horizontal direction opposite to the paste scraping direction for a predetermined time, and stopping the squeegee descending and moving the squeegee base in the horizontal direction when the squeegee contacts the upper surface of the mask;
Moving the squeegee base in the paste scraping direction with the squeegee in contact with the upper surface of the mask, and scraping the paste supplied to the upper surface of the mask with the squeegee to transfer the paste to the substrate. A characteristic screen printing method.

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