JP2008110538A - Screen printing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide screen printing equipment preventing electrostatic charging of a squeegee, without impairing workability, in the case of a floating structure being adopted. <P>SOLUTION: An attachment part 41 to which a squeegee unit 35 having a squeegee member 17 held by a squeegee holder 36 is attached detachably is supported by a lifting part 40 made to move upward and downward by a squeegee lifting mechanism and grounded electrically, in a state that it is allowed to rotate by an axial support part 44. In this floating structure, conductive parts 45 so provided as to be extensible and contractible vertically are disposed on both sides of the axial support part 44 and always brought into contact with the upper side of the attachment part 41 and the lower side of the lifting part 40. According to this constitution, the squeegee member 17 can always be made conductive to a grounding part and the electrostatic charging of the squeegee member 17 can be prevented without impairing workability, in the case when the floating structure is adopted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a screen printing apparatus that prints paste such as cream solder or conductive paste on a substrate.

  In an electronic component mounting process, screen printing is used as a method for printing paste such as cream solder or conductive paste on a substrate. In this method, a mask plate provided with a pattern hole in accordance with a printing target portion is brought into contact with the substrate, and a squeegee is slid in a state where paste is supplied onto the mask plate, whereby the substrate is passed through the pattern hole. The paste is printed on top.

In a squeegeeing operation in which a squeegee is slid by a mask plate, static electricity is generated by rubbing a squeegee made of an insulator such as an elastomer on a mask plate made of a thin metal plate. If the printing operation is continued while the static electricity is charged in the squeegee, if electronic components are already mounted on the substrate to be printed, there may be a problem that these electronic components are electrically damaged. For this reason, in a screen printing apparatus, conventionally, a squeegee is electrically grounded by a grounding wire to prevent the squeegee from being charged (for example, see Patent Document 1).
JP-A-61-225054

  By the way, the printing conditions when printing paste on a substrate by squeezing have become finer due to the type of substrate on which electronic components are mounted, that is, the material, thickness, etc., and it is necessary to make the squeegee evenly adhere to the mask plate. ing. For this reason, in the configuration of the squeegee head that holds the squeegee, a floating structure that allows rotation about the axis in the squeegeeing direction is used.

  In such a floating system, since the squeegee is held via a bearing used for the shaft support mechanism, the squeegee is in an electrically non-conducting state with respect to the apparatus main body electrically grounded in the squeegee head. For this reason, in order to prevent the squeegee from being charged, it is necessary to connect a ground wiring to the squeegee itself. However, if the grounding wiring is led to the squeegee, the grounding line becomes an obstacle in work such as maintenance around the squeegee, and the workability is hindered. As described above, in the conventional screen printing apparatus, when the floating structure is adopted, there is a problem that it is difficult to realize an antistatic structure that prevents the squeegee from being charged without impairing workability. .

  Therefore, an object of the present invention is to provide a screen printing apparatus that can prevent squeegee charging without impairing workability when a floating structure is employed.

In the screen printing apparatus of the present invention, the substrate is brought into contact with the mask plate provided with the pattern hole, and the plate-like squeegee member is slid on the mask plate supplied with the paste, thereby passing the pattern hole through the pattern hole. A screen printing apparatus for printing a paste on a substrate, wherein a squeegee unit is formed by holding the squeegee member on a squeegee holder, a mounting portion on which the squeegee unit is detachably mounted, and a squeegee lifting mechanism that moves up and down electrically An elevator unit grounded to the shaft, a shaft support unit that supports the mounting unit in a state in which the rotation of the squeegee member around the axis in the sliding direction is permitted, and both sides of the shaft support unit The squeegee member is lifted up and down through the mounting portion by contacting the upper surface of the mounting portion and the lower surface of the lifting portion. And a conductive portion for conducting a part.

  According to the present invention, the floating portion, in which the squeegee unit is detachably mounted, is supported by the lifting / lowering portion that is lifted / lowered by the squeegee lifting / lowering mechanism and electrically grounded in a state where the rotation is permitted by the shaft support portion. In the structure, a squeegee member is provided by disposing a conductive portion that is vertically extendable on both sides of the shaft support portion so that the conductive portion is in contact with the upper surface of the mounting portion and the lower surface of the lifting portion. The squeegee member can be prevented from being charged without impairing the workability when the floating structure is employed.

  Next, embodiments of the present invention will be described with reference to the drawings. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a front view of the screen printing apparatus according to an embodiment of the present invention, and FIGS. 3 and 4 are diagrams of an embodiment of the present invention. FIG. 5 is an explanatory view of a printing operation in the screen printing apparatus according to the embodiment of the present invention, and FIG. 6 is a diagram illustrating installation of the squeegee unit in the squeegee head of the screen printing apparatus according to the embodiment of the present invention. FIG. 7 is a partial sectional view of the squeegee head of the screen printing apparatus according to the embodiment of the present invention. FIG. 8 is an operation explanatory view of the squeegee head of the screen printing apparatus according to the embodiment of the present invention. .

  First, the structure of the screen printing apparatus will be described with reference to FIG. 1, FIG. 2, FIG. 3, and FIG. 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 substrate transport direction (X direction—the direction perpendicular to the paper surface in FIG. 1), and both end portions of the substrate 10 to be printed by these transport rails. It supports and conveys. 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 transport rail 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. Further, the substrate is positioned by the substrate positioning unit 1. Then, the substrate 10 after being printed by a screen printing mechanism described later is carried out downstream by the transport rail 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 disposed opposite to each other on the left and right sides, and the clamp member 9a on one side is advanced and retracted by the drive mechanism 9b to clamp and fix the substrate 10 from both sides (see FIG. (See also 4).

  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 a mask frame 11 held by a mask holder (not shown). The shape and position of an electrode 10 a to be printed on the substrate 10 are extended on the mask plate 12. Corresponding to (see FIG. 3), pattern holes 12a are provided. A squeegee driving mechanism 13 is disposed on the mask plate 12. The squeegee driving mechanism 13 includes two squeegee raising / lowering mechanisms 15 for raising and lowering a pair of squeegee heads 16 </ b> A and 16 </ b> B arranged to face the horizontal plate 14. The squeegee heads 16A and 16B coupled to the shaft 15a hold plate-like squeegee members 17, respectively.

  By driving the squeegee lifting mechanism 15, the squeegee heads 16 </ b> A and 16 </ b> B are individually lifted and lowered so that the squeegee member 17 contacts the upper surface of the mask plate 12. A feed screw 18 that is rotationally driven by a squeegee moving motor 19 is screwed to the nut 20 fixed to the lower surface of the plate 14. By driving the squeegee moving motor 19, the squeegee heads 16 </ b> A and 16 </ b> B together with the plate 14. Move horizontally in the Y direction (see also FIG. 2).

  As shown in FIG. 2, a guide rail 27 is disposed in the Y direction on a bracket 26 disposed on the vertical frame 25, and a slider 28 slidably fitted on the guide rail 27 is provided on the plate 14. Connected to both ends. Thereby, the squeegee drive mechanism 13 is slidable in the Y direction. The plate 14 is horizontally moved in the Y direction by a squeegee moving means comprising a nut 20, a feed screw 18 and a squeegee moving motor 19 (see FIG. 1) for rotationally driving the feed screw 18.

  In FIG. 2, a guide rail 30 is disposed on the vertical frame 25 in the Y direction, and a slider 31 slidably fitted to the guide rail 30 is coupled to the head X-axis table 24 via a bracket 24a. Yes. Thereby, the head X-axis table 24 is slidable in the Y direction. The head X-axis table 24 is horizontally moved in the Y direction by a head Y-axis moving mechanism 23 including a nut 33, a feed screw 32, and a head moving motor (not shown) that rotationally drives the feed screw 32.

  As shown in FIGS. 2 and 4, a camera head unit 21 is mounted on the head X-axis table 24. The camera head unit 21 includes a substrate recognition camera 21a for imaging the substrate 10 from above, and a mask recognition camera 21b for imaging the mask plate 12 from the lower surface side. By driving the X-axis table 24 and moving the camera head unit 21, recognition of the substrate 10 and recognition of the mask plate 12 can be performed simultaneously. When the substrate 10 and the mask plate 12 are not recognized by the camera head unit 21, the camera head unit 21 is in a position retracted from the upper side of the substrate positioning unit 1 as shown in FIG.

  Next, a printing operation by the screen printing mechanism will be described with reference to FIG. First, when the substrate 10 is carried into the printing position by the substrate transport mechanism 8, the second Z-axis table 6 is driven to raise the substrate receiving portion 7 and receive the lower surface of the substrate 10. In this state, the substrate positioning unit 1 is driven to align the substrate 10 with the mask plate 12. Thereafter, the first Z-axis table 5 is driven to raise the substrate 10 together with the substrate transport mechanism 8 so as to contact the lower surface of the mask plate 12 provided with the pattern holes 12a. Clamp. Thereby, the horizontal position of the board | substrate 10 is fixed in the squeegee which moves squeegee head 16A, 16B by the squeegee drive mechanism 13. FIG.

  In this state, one of the squeegee heads 16A and 16B is lowered in accordance with the squeegeeing direction in the squeezing operation to bring the squeegee member 17 into contact with the mask plate 12, and the cream solder 22 as paste is supplied. By sliding the squeegee member 17 in the squeezing direction (Y direction) on the mask plate 12, cream solder is printed on the substrate 10 through the pattern holes 12a.

  In this screen printing operation, static electricity is generated when the squeegee member 17 slides on the mask plate 12 or by friction during mask cleaning, but the periphery of the mask plate 12 is held via an insulator. Therefore, by repeatedly performing the screen printing operation, the squeegee member 17 and the mask plate 12 are charged to a high potential by static electricity.

  When the screen printing operation is performed while the mask plate 12 is charged in this way, if electronic components are already mounted on the substrate to be printed, these electronic components are damaged and the printing target is also printed. If these substrates are unmounted substrates, these substrates are sent to the subsequent process while being charged by the conductive charges from the mask plate, and there is a risk of damaging the electronic components mounted here. . Therefore, in the screen printing apparatus of the present embodiment, in the structure of the squeegee heads 16A and 16B described below, the squeegee member 17 and the grounding portion of the squeegee member 17 are electrically connected to each other, and the static electricity accumulated in the squeegee member 17 and the mask plate 12 is secured. Is surely released to the grounding part.

  The structure of the squeegee heads 16A and 16B will be described with reference to FIGS. As shown in FIG. 6 (a), the squeegee heads 16A and 16B are connected to a lifting / lowering part 40 made of conductive metal that is connected to a lifting / lowering shaft 15a of the squeegee lifting / lowering mechanism 15 and a mounting part 41 made of conductive metal. The squeegee unit 35 is detachably mounted on the mounting portion 41 while being supported rotatably via the support portion 44. The elevating part 40 is electrically connected to the grounding part via a conductive metal part or a grounding wire so that static electricity is not charged. That is, the elevating part 40 is raised and lowered by the squeegee elevating mechanism 15 and is electrically grounded.

  The squeegee unit 35 has a configuration in which an elongated rectangular plate-like squeegee member 17 is held by a squeegee holder 36. The squeegee holder 36 has a substantially F-shaped cross section so that the squeegee member 17 can be held in a posture inclined at a predetermined angle in the squeegeeing direction. It is fixed by being pinched. On the upper surface of the squeegee holder 36, rectangular block-like fitting portions 36a formed with pin fitting holes 36b are projected at two locations.

At both ends of the mounting portion 41, there are provided cutout portions 41a in which the mounting portion 41 is partially cut out so that the fitting portion 36a is fitted, and the notch portion 41a has a pin fitting hole 36b. Alignment pins 41b that fit in the horizontal direction are implanted in the horizontal direction. And the conduction | electrical_connection part 45 for electrically connecting the mounting part 41 and the raising / lowering part 40 is arrange | positioned in the both sides of the shaft support part 44, Furthermore, above the notch part 41a of the both sides of the conduction | electrical_connection part 45, A retaining mechanism 42 for locking the fitting portion 36a in a state where the squeegee unit 35 is mounted is provided.

  When the squeegee unit 35 is mounted on the mounting portion 41, as shown in FIG. 6B, the upper surface of the squeegee holder 36 abuts the lower surface of the mounting portion 41 and the fitting portion 36a is fitted to the notch portion 41a. To do. At the same time, the alignment pin 41b is fitted into the pin fitting hole 36b, whereby the squeegee holder 36 is held in the correct posture by the mounting portion 41. In this state, the squeegee member 17 is conducted to the elevating unit 40 through the squeegee holder 36, the mounting unit 41, and the conducting unit 45, and further conducted to the grounding unit.

  FIGS. 7A, 7B, and 7C show the AA, BB, and CC sections of FIG. 6B, respectively. FIG. 7A shows the structure of the shaft support portion 44. Bearings 47 are mounted on the two brackets 40 a provided to extend downward from both ends of the elevating unit 40. A projection 41c extending upward from the mounting portion 41 is inserted with a shaft stop pin 46 having a horizontal axis line a, and the shaft stop pin 46 is fitted to a bearing 47 to Both ends are prevented from coming off by retaining rings 48. Thereby, the mounting portion 41 is rotatable around the axis a of the shaft stop pin 46 disposed in the Y direction (sliding direction of the squeegee member 17) with respect to the elevating portion 40. That is, the shaft support portion 44 has a function of supporting the mounting portion 41 on the elevating portion 40 in a state where the rotation of the squeegee member 17 around the axis a in the sliding direction is permitted.

  In the structure of the shaft support portion 44, since the grease for lubrication is sealed in the bearing 47, the elevating portion 40 is not electrically connected to the shaft locking pin 46. Therefore, the elevating portion 40 is mounted. It is in a state of being electrically insulated from the portion 41. For this reason, static electricity generated in the squeegee member 17 during the squeegeeing operation does not flow to the elevating unit 40 via the shaft support portion 44, and the squeegee member 17 is charged as it is. In order to prevent such charging of the squeegee member 17, in the present embodiment, a conductive portion 45 as described below is provided for the purpose of surely connecting the mounting portion 41 to the elevating portion 40. .

  FIG. 7B shows the structure of the conduction part 45. A vertical stopper shaft 49 is implanted on the upper surface of the mounting portion 41. The stopper shaft 49 has a function of restricting the rotation angle when the mounting portion 41 rotates about the shaft stop pin 46 of the shaft support portion 44. That is, when the top portion of the stopper shaft 49 is not in contact with the elevating portion 40, the mounting portion 41 is allowed to rotate around the shaft support portion 44, whereby the mask plate 12 is somewhat inclined with respect to the horizontal plane. In this case, the squeegee member 17 is made to follow the surface of the mask plate 12 to maintain the adhesion in the squeezing operation.

  On the outer periphery of the stopper shaft 49, conductive spring members 50 made of conductive metal are mounted vertically. The conductive spring member 50 is a compression spring, and always contacts the upper surface 41 d of the mounting portion 41 and the lower surface 40 b of the elevating portion 40 by the urging force in the extension direction. As a result, the conductive spring member 50 causes the mounting portion 41 and the lifting / lowering portion 40 to conduct, and further the squeegee member 17 conducts to the lifting / lowering portion 40 via the mounting portion 41. That is, the conductive spring member 50 used for the conductive portion 45 is provided so as to be vertically extendable on both sides of the shaft fulcrum 44, and comes into contact with the upper surface 41d of the mounting portion 41 and the lower surface 40b of the elevating portion 40. 17 is connected to the elevating part 40 via the mounting part 41.

FIG. 7C shows the structure of the retaining mechanism 42. On the upper surface of the mounting portion 41, a locking member 51 provided with a hook-shaped locking portion 51a at the front end is disposed in the horizontal direction. The locking member 51 is guided to move up and down by a guide post 52 erected on the upper surface of the mounting portion 41 and is always pressed downward by a spring member 53 mounted on the outer periphery of the guide post 52. The locking portion 51a is provided with an overhang-shaped taper surface 51b. By contacting an object from the front surface side (left side in the drawing) with respect to the taper surface 51b, the locking portion 51a Displaces upward against the urging force.

  With this configuration, when the positioning pin 41b is fitted into the pin fitting hole 36b and the squeegee unit 35 is attached to the attachment portion 41, the attachment portion 36a slides on the tapered surface 51b on the front surface of the locking portion 51a. It touches and fits into the notch 41a while pushing up the locking part 51a. When the fitting operation is completed, the locking portion 51a locks the front surface of the fitting portion 36a as shown in FIG. 7C. That is, the squeegee unit 35 can be mounted on the mounting portion 41 by a one-touch operation. And the fitting part 36a does not fit in and remove from the mounting state in which the alignment pin 41b is fitted into the pin fitting hole 36b, and the squeegee unit 35 is securely attached to the mounting part 41.

  Next, operations of the squeegee heads 16A and 16B in squeezing will be described with reference to FIG. FIG. 8A shows a state in which the squeegee raising / lowering mechanism 15 is driven to lower the squeegee heads 16A and 16B with respect to the mask plate 12. As shown in FIG. The squeegee member 17 held by the squeegee holder 36 contacts the upper surface of the mask plate 12. At this time, if the mask plate 12 is not correctly mounted horizontally and is inclined to the lower right by α1 degrees as shown in FIG. 8C, the mounting portion 41 moves around the shaft support portion 44. The squeegee member 17 comes into close contact with the inclination of the upper surface of the mask plate 12.

  Similarly, as shown in FIG. 8D, the squeegee member 17 is masked by rotating the mounting portion 41 around the shaft support portion 44 in the case where it is inclined by α2 degrees to the lower right. The plate 12 adheres following the inclination of the upper surface of the plate 12. In either case of FIG. 8C or FIG. 8D, the conductive spring member 50 always expands and contracts in the conductive portion 45 so that the elevating portion 40 and the mounting portion 41 are always in contact with each other. Keep. Thereby, in the squeegeeing operation in which the squeegee member 17 slides with respect to the mask plate 12, static electricity generated in the squeegee member 17 and the mask plate 12 due to friction always flows to the lift unit 40 that is grounded. Therefore, there is no problem due to the accumulation of charges in the squeegee member 17 and the mask plate 12.

  8C and 8D, when the mask plate 12 is in an inclined state, the stretchable conductive spring member 50 is used for the conductive portion 45, so that the mounting member 41 can be removed. Thus, it is possible to obtain an effect that the followability of the squeegee member 17 to the upper surface of the mask plate 12 can be improved by applying an inferior force.

  As described above, in the screen printing apparatus shown in the present embodiment, the mounting portion 41 to which the squeegee unit 35 is detachably mounted is moved up and down by the squeegee lifting mechanism 15 and is electrically grounded. In the floating structure in which the shaft support part 44 is supported in a state in which the rotation is allowed, a conduction part 45 that is vertically extendable on both sides of the shaft support part 44 is arranged to move up and down the upper surface of the mounting part 41. A configuration is adopted in which the conducting portion is always in contact with the lower surface of the portion 40. Thereby, the squeegee member 17 can be always conducted to the grounding portion. Therefore, it is not necessary to introduce a dedicated grounding wire to the squeegee member 17, and when the floating structure is employed, charging of the squeegee member 17 can be prevented without impairing workability.

  The screen printing apparatus of the present invention has an effect of preventing the squeegee from being charged without impairing workability when the floating structure is adopted, and prints paste such as cream solder or conductive paste on the substrate. It is useful in the field to do.

The side view of the screen printing apparatus of one embodiment of this invention 1 is a front view of a screen printing apparatus according to an embodiment of the present invention. The top 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 Explanatory drawing of the printing operation in the screen printing apparatus of one embodiment of this invention Explanatory drawing of the mounting structure of the squeegee unit in the squeegee head of the screen printing apparatus of one embodiment of this invention. The fragmentary sectional view of the squeegee head of the screen printing apparatus of one embodiment of this invention Explanatory drawing of operation | movement of the squeegee head of the screen printing apparatus of one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Board | substrate 12 Mask plate 12a Pattern hole 13 Squeegee drive mechanism 15 Squeegee raising / lowering mechanism 16A, 16B Squeegee head 17 Squeegee member 22 Cream solder (paste)
35 Squeegee Unit 36 Squeegee Holder 40 Elevating Part 41 Mounting Part 42 Detachment Mechanism 44 Shaft Support Part 45 Conducting Part 50 Conducting Spring Member

Claims (1)

Screen printing that prints the paste on the substrate through the pattern holes by bringing the substrate into contact with the mask plate provided with the pattern holes and sliding the plate-like squeegee member on the mask plate supplied with the paste A device,
A squeegee unit formed by holding the squeegee member on a squeegee holder, a mounting portion on which the squeegee unit is detachably mounted, a lifting portion that is lifted and lowered by a squeegee lifting mechanism and electrically grounded, and the mounting portion A shaft support portion that is supported by the elevating portion in a state in which the squeegee member is allowed to rotate about an axis in a sliding direction; and an upper surface of the mounting portion that is vertically extendable on both sides of the shaft support portion; A screen printing apparatus, comprising: a conduction portion that brings the squeegee member into conduction with the elevation portion via the mounting portion by contacting a lower surface of the elevation portion.

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