JP2013043362A - Screen printing apparatus and screen printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen printing apparatus and a screen printing method, capable of highly accurately detecting the remaining state of paste on a mask plate.SOLUTION: Brackets 19 are disposed to a frame 14 to be positioned to the outside on each side of a squeegee member 17 when seen from a squeezing operation direction. A projector 20A is held by a lower end part of one bracket 19, and a light receiver 20B is held by a lower end of the other bracket 19. When the light receiver 20B receives inspection light from the projector 20A at predetermined timing in ascending operation of the squeegee member 17, a display part 36 displays a notification image indicating that an amount of a cream solder P on the mask plate 12 is small, by a command from a notification processing part 34. Therefore, adhesion of the cream solder P to the projector 20A or the light receiver 20B is suppressed to enhance reliability in detection of the remaining state of cream solder P.

Description

  The present invention relates to a screen printing apparatus and a screen printing method for printing a paste on a substrate.

  In an electronic component mounting process, screen printing is used as a method for printing paste such as cream solder on a substrate. In this method, the pattern hole is formed by performing a squeegeeing operation in which a substrate is brought into contact with a mask plate provided with a pattern hole in accordance with a printing target portion, a paste is supplied onto the mask plate, and a squeegee is slid. The paste is printed on the substrate.

  By repeating the printing operation, the amount of paste on the mask plate gradually decreases, but in order to check the amount of this paste, a screen printing apparatus having a function of detecting the residual state of the paste by a sensor attached to the squeegee It is known (see, for example, Patent Document 1). As a result, the remaining state of the paste is detected by the sensor, and the printing conditions such as the squeegee push-in stroke are properly set. If it is determined that the amount of the paste is small, a new paste is replenished. be able to.

Japanese Patent No. 3444625

  However, in the prior art in which the sensor is provided in the squeegee including the above-mentioned patent document, the distance between the paste to be detected and the sensor is close, so that the paste easily adheres to the sensor in the squeezing operation. There is a problem that the reliability of detection of the residual state is lowered.

  Accordingly, an object of the present invention is to provide a screen printing apparatus and a screen printing method that can accurately detect the residual state of paste on a mask plate.

  In the first aspect of the present invention, the substrate is brought into contact with the mask plate provided with the pattern holes, and the plate-like squeegee member is slid by the squeegee moving means on the mask plate supplied with the paste. A screen printing apparatus for printing the paste on the substrate through the pattern hole, a squeegee holder to which the squeegee member is mounted, an elevating unit for elevating the squeegee holder with respect to the mask plate, and the elevating And a frame that is moved by the squeegee moving unit, and a detecting unit that detects a residual state of the paste that is disposed on the frame and scraped by the squeegee member on the mask plate.

  According to a third aspect of the present invention, there is provided a squeegee holder on which a squeegee member is mounted, lifting means for moving the squeegee holder up and down relative to a mask plate provided with a pattern hole, and sliding the squeegee member on the mask plate. A squeegee moving means to be moved; a frame in which the elevating means is arranged and moved by the squeegee moving means; and a residual state of the paste moved by the squeegee member on the mask plate by moving together with the frame. The paste is applied to the substrate that is in contact with the mask plate through the pattern hole by performing a squeegeeing operation in which the squeegee member is slid on the mask plate using a screen printing apparatus provided with detection means. A screen printing method for printing, wherein the squeezing operation is terminated. Wherein at a predetermined timing in rising operation by the lifting means of the squeegee member, detecting residual state of scraper pastes by the squeegee member on said mask plates.

  According to the present invention, the detecting means for detecting the residual state of the paste scraped by the squeegee member on the mask plate is not moved by the squeegee holder to which the squeegee member is attached, but is moved by the squeegee moving means. Therefore, it is possible to prevent the paste from adhering to the detection means and to improve the reliability of detecting the residual state of the paste.

1 is a front view of a screen printing apparatus according to an embodiment of the present invention. The side view of the screen printing apparatus of one embodiment of this invention The top view of the screen printing apparatus of one embodiment of this invention 1 is a configuration diagram of a squeegee head that constitutes a screen printing apparatus according to an embodiment of the present invention. 1 is a block diagram of a control system of a screen printing apparatus according to an embodiment of the present invention. Operation explanatory diagram of screen printing according to an embodiment of the present invention Operation explanatory diagram of screen printing according to an embodiment of the present invention The figure which shows the detection of the residual state of the paste of one embodiment of this invention The figure which shows the detection of the residual state of the paste of one implementation form of this invention The figure which shows the structure of the squeegee head in a prior art.

  First, the structure of the screen printing apparatus will be described with reference to FIGS. In FIG. 1, the screen printing apparatus is configured by disposing a screen printing mechanism above a substrate positioning unit 1. The substrate positioning unit 1 is configured by stacking a Y-axis table 2, an X-axis table 3, and a θ-axis table 4, and further combining a first Z-axis table 5 and a second Z-axis table 6 thereon. Yes.

  The configuration of the first Z-axis table 5 will be described. Similarly, on the upper surface side of the horizontal base plate 4 a provided on the upper surface of the θ-axis table 4, the horizontal base plate 5 a is held up and down by an elevating guide mechanism (not shown). The base plate 5a is moved up and down by a Z-axis lifting mechanism configured to rotationally drive a plurality of feed screws 5c through a belt 5d by a motor 5b.

  A vertical frame 5e is erected on the base plate 5a, and a substrate transport mechanism 8 is held at the upper end of the vertical frame 5e. The substrate transport mechanism 8 includes two transport rails arranged in parallel to the X direction which is the substrate transport direction, and supports and transports both ends of the substrate 10 to be printed by these transport rails. Note that the Y direction, which is a direction orthogonal to the X direction, is a squeezing operation direction (sliding direction of the squeegee member 17) for sliding the squeegee member 17 on the mask plate 12 described later. By driving the first Z-axis table 5, the substrate 10 held by the substrate transport mechanism 8 can be lifted and lowered with respect to the screen printing mechanism described later together with the substrate transport mechanism 8. As shown in FIGS. 2 and 3, the substrate transport mechanism 8 extends to the upstream side (left side in FIGS. 2 and 3) and the downstream side, and the substrate 10 carried from the upstream side is transported by the substrate transport mechanism 8. Furthermore, it is positioned by the substrate positioning unit 1. Then, the substrate 10 after being printed by a screen printing mechanism to be described later is carried out downstream by the substrate transport mechanism 8.

  The configuration of the second Z-axis table 6 will be described. A horizontal base plate 6a is disposed between the substrate transport mechanism 8 and the base plate 5a so as to be movable up and down along a lifting guide mechanism (not shown). The base plate 6a is moved up and down by a Z-axis lifting mechanism configured to rotationally drive a plurality of feed screws 6c through a belt 6d by a motor 6b. On the upper surface of the base plate 6a, there is disposed a substrate lower receiving portion 7 having a lower receiving surface for holding the substrate 10 on the upper surface.

  By driving the second Z-axis table 6, the substrate receiving unit 7 moves up and down with respect to the substrate 10 held by the substrate transport mechanism 8. The substrate receiving portion 7 supports the substrate 10 from the lower surface side when the lower receiving surface of the substrate lower receiving portion 7 contacts the lower surface of the substrate 10. A clamp mechanism 9 is disposed on the upper surface of the substrate transport mechanism 8. The clamp mechanism 9 includes two clamp members 9a that are arranged opposite to each other on the left and right sides. The clamp member 9a on one side is advanced and retracted by the clamp drive mechanism 9b, thereby clamping and fixing the substrate 10 from both sides.

  Next, the screen printing mechanism disposed above the substrate positioning unit 1 will be described. 1 and 2, a mask plate 12 is extended on the mask frame 11, and pattern holes corresponding to the shape / position (see FIG. 3) of the electrodes 10a to be printed on the substrate 10 are formed on the mask plate 12. 12a is provided. On the mask plate 12, cream solder P as a paste is supplied by a cream solder supply mechanism (not shown).

  1, 2, and 4, a squeegee head 13 is disposed on the mask plate 12. The squeegee head 13 has a configuration in which a pair of squeegee raising / lowering mechanisms 15 for independently raising and lowering a pair of squeegee holders 16 having the same configuration are disposed on a horizontal frame 14. As shown in FIG. 4, the pair of squeegee lifting mechanisms 15 disposed on the upper surface of the frame 14 has a lifting shaft 15a extending downward from the lower portion, and at the lower end of each lifting shaft 15a, A squeegee holder 16 to which a plate-like squeegee member 17 is attached is fixed.

  By driving the squeegee raising / lowering mechanism 15, the squeegee holder 16 is raised and lowered (arrow “a”), whereby the lower end portion of the squeegee member 17 comes into contact with the upper surface of the mask plate 12. That is, the squeegee elevating mechanism 15 is an elevating means for elevating the squeegee holder 16 with respect to the mask plate 12. In FIG. 4, plate-like paste leakage preventing members for preventing leakage of cream solder P in the X direction perpendicular to the Y direction on both sides of the squeegee member 17 as viewed from the Y direction which is the squeezing operation direction. 18 are provided (see also FIG. 9A). The cream solder P is supplied to a position surrounded by the paste leakage preventing member 18 as viewed from the squeezing operation direction (see FIG. 9A). In FIG. 1, FIG. 6, FIG. 7, the paste leakage preventing member 18 is omitted for convenience.

  In FIG. 4, a bracket 19 is provided on the frame 14 so as to extend downward in the arrangement direction of the mask plate 12. As shown in FIG. 2, the brackets 19 are respectively disposed on the frames 14 so as to be located on both sides of the squeegee member 17 when viewed from the squeezing operation direction, and an optical sensor is provided at the lower end of one bracket 19. The light projector 20A is also held at the lower end of the other bracket 19, and a light receiver 20B is also held as an optical sensor. As shown in FIGS. 2 and 4, the centers T of the projector 20A and the light receiver 20B are located on the same straight line in the X direction.

  The linear inspection light projected horizontally in the X direction from the center T of the projector 20A is directed to the light receiver 20B (arrow b shown in FIG. 2), and the inspection light is determined depending on whether or not the inspection light is received by the light receiver 20B. The presence or absence of an inspection object (here, cream solder P) on the road is optically detected. Since the bracket 19 is provided on the frame 14 independently of the squeegee holder 16 that can be moved up and down by the squeegee lifting mechanism 15, the distance L1 in the vertical direction from the center T of the projector 20A and the light receiver 20B to the upper surface of the mask plate 12 is provided. When the squeegee member 17 is lowered and its lower end is in contact with the lower surface of the mask plate 12, the distance L2 in the horizontal direction from the center T of the light projector 20A and the light receiver 20B to the squeegee member 17 is always constant. (See FIG. 4). In the above configuration, the position of the center T of the projector 20A and the light receiver 20B is the detection position of the inspection object set on the sliding direction side of the squeegee member 17.

  Next, a moving mechanism for moving the squeegee head 13 will be described. As shown in FIG. 2, guide rails 22 are arranged on the vertical frame 21 in the Y direction. Sliders 23 slidably fitted on the guide rails 22 are attached to both ends of the frame 14 via blocks 24. Are combined. As a result, the squeegee head 13 including the frame 14 is horizontally moved in the Y direction by a squeegee moving means including a nut 25, a feed screw 26, and a squeegee moving motor (not shown) that rotationally drives the feed screw 26. In the above configuration, the frame 14 is provided with lifting means and is moved by the moving means.

  Next, the configuration of the control system of the screen printing apparatus will be described with reference to FIG. In FIG. 5, the control unit 30 is an arithmetic processing device provided in the screen printing apparatus, and includes a storage unit 31, a mechanism driving unit 32, an optical sensor control unit 33, and a notification processing unit 34. The operation / input unit 35 is input means such as a keyboard and a mouse, and inputs operation commands and data. The display unit 36 is a display device such as a liquid crystal panel, and a notification image indicating that the amount of cream solder P on the mask plate 12 is small according to a guidance screen at the time of input by the operation / input unit 35 or a command from the notification processing unit 34. Is displayed.

  Next, the control unit 30 will be described. The storage unit 31 stores a processing program for driving and controlling each mechanism of the screen printing apparatus and a processing program for controlling an optical sensor including the projector 20A and the light receiver 20B. The mechanism drive unit 32 drives each mechanism of the substrate positioning unit 1, the substrate transport mechanism 8, the cream solder supply mechanism 37, the clamp drive mechanism 9 b, the squeegee lifting mechanism 15, and the squeegee moving means 38 according to the processing program stored in the storage unit 31. Control. The optical sensor control unit 33 controls the optical sensor including the projector 20A and the light receiver 20B according to the processing program stored in the storage unit 31. The notification processing unit 34 receives a signal transmitted from the optical sensor control unit 33 when the light receiver 20B receives the inspection light, and displays a notification image indicating that the amount of the cream solder P is small on the display unit 36. A process of transmitting a power signal is performed. That is, the notification processing unit 34 and the display unit 36 serve as notification means for notifying the worker that the amount of cream solder P is small.

  Next, a printing operation by the screen printing mechanism will be described with reference to FIGS. First, when the substrate 10 is carried into the printing position by the substrate transport mechanism 8, as shown in FIG. 6A, the second Z-axis table 6 is driven to raise the substrate receiving portion 7, and the substrate 10 Underside the lower surface. In this state, the substrate 10 is sandwiched and fixed by the clamp member 9 a, and the substrate positioning unit 1 is driven to align the substrate 10 with the mask plate 12. Thereafter, as shown in FIG. 6B, the first Z-axis table 5 is driven to raise the substrate 10 together with the substrate receiving portion 7 so as to contact the lower surface of the mask plate 12.

  In this state, the cream solder P is scraped by the squeegee member 17 by performing a squeegeeing operation in which the squeegee member 17 is slid in the Y direction on the mask plate 12 to which the cream solder P is supplied. Thereby, the cream solder P is printed at a predetermined location of the substrate 10 through the pattern hole 12a. The squeegeeing operation is performed by lowering one of the pair of squeegee holders 16 according to the traveling direction.

  The squeezing operation will be described in detail with reference to FIG. For convenience, in FIG. 7, the left squeegee holder is 16A, and the right squeegee holder is 16B. As shown in FIG. 7A, when the squeegeeing operation is performed in the direction of the arrow c, the squeegee head 13 is moved on the clamp member 9a located on the left side in FIG. The squeegee holder 16A is lowered (arrow d) by the squeegee lifting mechanism 15 so that the lower end portion of the squeegee member 17 is brought into contact with the upper surface of the mask plate 12. In this state, the squeegee head 13 is moved in the direction of arrow c. (See also FIG. 7 (b)). At this time, the squeegee head 13 is moved to a position where the cream solder P that has been scraped is positioned on the clamping member 9a on the squeezing operation direction side (right side in FIG. 7B). When the squeegeeing operation is finished, the squeegee holder 16A is raised (arrow e) by the squeegee lifting mechanism 15 as shown in FIG.

  When the squeegeeing operation is performed in the direction opposite to the direction of the arrow c, the right squeegee holder 16B is lowered to bring the lower end portion of the squeegee member 17 attached to the squeegee holder 16B into contact with the mask plate 12, In this state, the squeegee head 13 is moved in the forward and reverse directions with respect to the arrow c direction by the squeegee moving means. When the squeezing operation is finished, the squeegee holder 16B is raised.

  Next, detection of the remaining state of the cream solder P supplied onto the mask plate 12 will be described. As the squeezing operation is repeated, the cream solder P on the mask plate 12 gradually decreases. For this reason, it is necessary to detect the remaining state of the cream solder P at a predetermined timing, and to replenish the cream solder P according to the detected remaining state.

  8A and 8B are enlarged views of parts of FIGS. 7B and 7C, respectively. In FIG. 8A, the cream solder P is squeezed on the mask plate 12 where the right clamp member 9a is positioned downward by a squeezing operation in the direction of arrow c (see FIG. 7A). ing. At this time, the inspection light is projected from the center T of the light projector 20A toward the light receiver 20B. However, the inspection light is blocked from being projected onto the light receiver 20B by the paste leakage prevention member 18. (See also FIG. 9 (a)).

  Thereafter, as shown in FIG. 8B, the squeegee member 17 and the paste leakage preventing member 18 are also raised with the rise of the squeegee holder 16 </ b> A (arrow e) by the squeegee raising / lowering mechanism 15. Since the cream solder P has viscosity, a part of the cream solder P adhering to the squeegee member 17 and the paste leakage preventing member 18 extends upward following these rising members. Then, when the paste leakage preventing member 18 rises, the light shielding by the paste leakage preventing member 18 is released. The detection of the remaining state of the cream solder P is performed by detecting whether or not the light receiver 20B has received the inspection light at a predetermined timing in the ascending operation of the squeegee member 17 after the light shielding by the paste leakage preventing member 18 is released. This is performed by the control unit 33 detecting it.

  When the cream solder P is present on the inspection optical path (in other words, in the horizontal direction of the center T of the projector 20A) at a predetermined timing in the ascending operation of the squeegee member 17 as in the case 1 of FIG. Is blocked by the cream solder P (see also FIG. 9 (b)). In such a case, since the optical receiver 20B does not receive the inspection light, the optical sensor control unit 33 does not transmit a signal to the notification processing unit 34. As a result, the notification unit does not perform notification and the squeezing operation is continuously performed. The

  On the other hand, when the cream solder P does not exist on the inspection optical path at a predetermined timing in the ascending operation of the squeegee member 17 as in the case 2 of FIG. 8B, the inspection light reaches the light receiver 20B (FIG. 9). (See also (c)). When the optical sensor control unit 33 detects the reception of the inspection light by the light receiver 20B, the optical sensor control unit 33 transmits a signal to the notification processing unit 34, and the notification processing unit 34 receives the signal and the amount of the cream solder P to the display unit 36. A signal indicating that a notification image indicating that there is little is to be displayed is transmitted.

  As described above, in the present embodiment, the cream solder P scraped by the squeegee member 17 on the mask plate 12 at a predetermined timing in the ascending operation of the squeegee member 17 after the squeegee operation by the squeegee lifting mechanism 15. The residual state is detected. The detection of the remaining state of the cream solder P is performed by determining whether or not the light receiver 20B has received the inspection light projected from the light projector 20A at a predetermined timing in the ascending operation of the squeegee member 17. Is performed by detecting.

  That is, when the light receiver 20B does not receive the inspection light at a predetermined timing in the ascending operation of the squeegee member 17, the notification processing unit 34 determines that the amount of the cream solder P on the mask plate 12 is sufficient. While the above notification is not performed, when the light receiver 20B receives the inspection light at a predetermined timing, the notification processing unit 34 performs the above notification that the amount of the cream solder P is insufficient. That is, in the present embodiment, the cross-sectional widths W1 and W2 of the cream solder P as viewed from the direction orthogonal to the sliding direction of the squeegee member 17 are detected using the light projector 20A and the light receiver 20B. A residual state is detected (see FIG. 8B).

  The predetermined timing for detecting the remaining state of the cream solder P can be arbitrarily set by an operator. However, since the viscosity of the paste containing the cream solder P varies depending on the type, the squeegee member 17 moves up. It is desirable to detect the residual state of the paste immediately after the start and immediately after the light shielding state by the paste leakage preventing member 18 is released. Thereby, a highly reliable detection accuracy can be realized for any paste having different viscosities.

  In the above configuration, the bracket 19, the projector 20 </ b> A, and the light receiver 20 </ b> B serve as detection means that detects the residual state of the paste scraped by the squeegee member 17 on the mask plate 12. Move with. The light projector 20A and the light receiver 20B are disposed outside the squeegee member 17, and the paste is orthogonal to the sliding direction of the squeegee member 17 in a horizontal plane at a predetermined detection position set on the sliding direction side of the squeegee member 17. The optical sensor detects optically from the direction. Further, the bracket 19 serves as a holding means for holding the optical sensor.

  As described above, the projector 20A and the light receiver 20B are provided not on the squeegee holder 16A to which the squeegee member 17 is attached but on the frame 14 and disposed outside the squeegee member 17 as viewed from the squeegee operation direction. Can be prevented from adhering to the projector 20A and the light receiver 20B, and the reliability of detecting the residual state of the cream solder P can be improved.

  As one of the prior arts for detecting the remaining state of the cream solder P, as shown in FIG. 10, the paste leakage preventing member 18A is provided with a slit S, and the cream solder P is rolled from the slit S during the squeezing operation. A method of visually checking the state is widely known. However, this conventional technique has a problem that as the squeezing operation is continued, the cream solder P adheres to the slit S, and the rolling state of the cream solder P cannot be confirmed. Moreover, the removal work of the cream solder P adhering to the slits S has a great labor and labor for workers, and has also become a factor of reducing productivity.

  On the other hand, according to the present invention, the optical sensors (projector 20A, light receiver) disposed on the outer sides of both sides of the squeegee member 17 at a predetermined timing in the ascending operation of the squeegee member 17 after finishing the squeegeeing operation. Since the residual state of the cream solder P is detected by 20B), it is not necessary to provide a slit in the paste leakage preventing member 18. Therefore, the above-described failure in detecting the residual state does not occur, and there is no need to remove the cream solder P. In addition, the situation where the cream solder P leaks from the slits to contaminate the mask plate 12 and the leaked cream solder P adheres to the optical sensor does not occur.

  The optical sensor is not limited to the projectors 20A and 20B described above, and various optical sensors can be used. For example, a projector for projecting inspection light on the lower end of one bracket 19 is provided, and a reflector for reflecting the inspection light projected on the lower end of the other bracket 19 in the forward and reverse directions is provided. The remaining state of the cream solder P may be detected based on whether the projector receives the inspection light.

  The notification that the amount of cream solder P has decreased is not limited to the configuration using the display unit 36 described above. For example, a warning lamp provided in the screen printing apparatus is turned on or a warning sound is generated. Various configurations can be used, such as notifying personnel. Further, the position of the center T of the light projector 20A and the light receiver 20B (optical sensor) may be arbitrarily set by an operator based on paste characteristics, various experiments, and the like.

  According to the present invention, it is possible to detect a residual state of a highly reliable paste, which is particularly useful in the field of electronic component mounting in which an electronic component is mounted by printing the paste on a substrate.

DESCRIPTION OF SYMBOLS 10 Board | substrate 12 Mask plate 14 Frame 15 Squeegee raising / lowering mechanism 16 Squeegee holder 17 Squeegee member 19 Bracket 20A Light projector 20B Light receiver P Cream solder

Claims (4)

A substrate is brought into contact with a mask plate provided with a pattern hole, and a plate-like squeegee member is slid by the squeegee moving means on the mask plate supplied with paste, thereby allowing the substrate to contact the substrate through the pattern hole. A screen printing apparatus for printing the paste,
A squeegee holder fitted with the squeegee member;
Elevating means for elevating the squeegee holder relative to the mask plate;
A frame in which the elevating means is disposed and moved by the squeegee moving means;
A screen printing apparatus comprising: detecting means for detecting a residual state of paste disposed on the frame and scraped by the squeegee member on the mask plate.   The detecting means is disposed outside the squeegee member and optically transmits the paste from a direction orthogonal to the sliding direction of the squeegee member in a horizontal plane at a predetermined detection position set on the sliding direction side of the squeegee member. The screen printing apparatus according to claim 1, further comprising an optical sensor for automatically detecting. A squeegee holder to which a squeegee member is attached; elevating means for elevating and lowering the squeegee holder relative to a mask plate provided with a pattern hole; squeegee moving means for sliding the squeegee member on the mask plate; A screen printing apparatus comprising: a frame provided with means and moved by the squeegee moving means; and a detecting means for detecting a residual state of the paste moved by the squeegee member on the mask plate. A screen printing method for printing the paste on a substrate that is in contact with the mask plate through the pattern hole by performing a squeegeeing operation to slide the squeegee member on the mask plate,
A screen that detects a residual state of the paste squeezed by the squeegee member on the mask plate at a predetermined timing in the ascending operation of the squeegee member that has finished the squeegeeing operation. Printing method.   The detection means includes an optical sensor disposed outside the squeegee member, and the paste is placed in a sliding plane and a horizontal plane of the squeegee member at a predetermined detection position set on the sliding direction side of the squeegee member. 4. The screen printing method according to claim 3, wherein optical detection is performed from directions orthogonal to each other.

Images