JP4391365B2 - Screen printing device - Google Patents

Description

  The present invention relates to a screen printing apparatus for applying paste such as cream solder to a substrate such as a printed circuit board.

  Conventionally, a mask sheet (hereinafter referred to as a mask) is placed on a substrate set on a stage, and a paste such as cream solder or conductive paste supplied on the mask is expanded with a squeegee, thereby opening the mask. A screen printing apparatus that applies (prints) a paste to a predetermined position on a substrate via a section is generally known.

  Conventionally, this type of screen printing apparatus has a head provided with a pair of squeegees having different inclination directions so that the squeegee can be moved up and down, and pastes paste by alternately using the pair of squeegees while reciprocating the head along the mask. Although the mainstream was the one that expands, it is difficult to keep the printing load during forward and backward movements uniform because the squeegee is raised and lowered separately, and the squeegee contact angle with the mask is free. There were problems such as low degree.

In recent years, for example, as disclosed in Patent Document 1, a screen printing apparatus has been proposed in which a squeegee is supported so as to be rotatable (swingable) about an axis parallel to the longitudinal direction of the head. According to this apparatus, the contact angle with respect to the mask can be arbitrarily set only by driving the squeegee around the axis, and the squeegee can be driven up and down by a single mechanism, so that it is easy to keep the printing load in the forward and backward directions uniform. .
JP-A-10-323964

  The screen printing apparatus disclosed in Patent Document 1 is advantageous in terms of the degree of freedom in setting the angle of the squeegee or the printing load, but has the following problems to be solved.

  That is, the squeegee is properly used according to the size of the mask and the type of paste. However, in the apparatus of Patent Document 1, the squeegee is integrally fixed to the squeegee holder, and this holder is assembled to the holder member of the head. Since the squeegee is supported to the head by directly connecting the holder to the rotation drive mechanism, the squeegee holder is further rotated while assembling the squeegee holder (holding the squeegee) to the holder member when replacing the squeegee. It is necessary to connect to the drive mechanism, and the work is extremely complicated and the workability is poor.

  The present invention has been made in view of the above circumstances, and aims to improve workability at the time of squeegee replacement in a screen printing apparatus that supports a squeegee so that the squeegee can rotate (swing) with respect to a head. Yes.

In order to solve the above problems, a screen printing apparatus of the present invention includes a head that supports a squeegee and relatively reciprocally moves the squeegee along a mask sheet superimposed on a substrate. In the screen printing apparatus in which the squeegee is supported so as to be rotatable about an axis orthogonal to the moving direction, the squeegee is provided on the head so as to be rotatable about the axis, and is connected to a rotation driving mechanism. A squeegee assembling portion that can be driven to rotate about an axis is provided, and a squeegee holder that holds the squeegee is detachably assembled to the squeegee assembling portion, and the squeegee has a work surface that presses the paste. Provided with edge portions at both ends, the work surface faces the traveling direction when the head is moved, and one of the edge portions is the edge portion when the squeegee moves forward The squeegee is configured to be displaced by the operation of the rotary drive mechanism so that the edge of the other side contacts the mask sheet when the squeegee moves backward, while the squeegee moves backward. Once facing the mask sheet and facing the opposite side, the edge portion contacts the mask sheet, and this contact position is behind the contact position of the edge portion with respect to the mask sheet at the end of movement before the reversing operation. the squeegee is shall be arranged so as to be located (claim 1).

According to this screen printing apparatus, since the squeegee holder is assembled to the squeegee assembling portion that is rotatably supported by the head and is connected in advance so as to be able to transmit drive to the drive source, At the time of assembly to the head, the troublesome work of connecting the holder to the rotation drive mechanism while assembling the squeegee holder as in the prior art becomes unnecessary, and squeegee replacement can be performed easily and quickly. In addition, the paste is not dragged in the printing operation after switching the advancing direction, that is, after switching from the forward movement to the backward movement (reverse movement to forward movement), and the printing operation can proceed well.

  In this apparatus, as a fixing means for assembling and fixing the squeegee holder to the squeegee assembling part, a fixed state in which the squeegee holder is fixed to the squeegee assembling part and a squeegee assembling based on one kind of operation. It is preferable that a fixing means is provided that can be switched to a non-fixed state in which the squeegee holder can be removed from the portion (Claim 2).

  According to this configuration, the squeegee holder can be attached to and detached from the squeegee assembling part more easily and quickly.

  As a specific configuration, for example, the fixing means is provided on the squeegee holder, a screw shaft portion provided integrally with the squeegee holder, a fixing nut member screwed onto the tip of the screw shaft portion, and the squeegee assembly portion. The screw shaft portion includes a notch portion formed so that the screw shaft portion can be inserted, the squeegee holder is overlaid on the squeegee assembly portion, and the fixing nut member is tightened in a state where the screw shaft portion is inserted into the notch portion. Thus, the squeegee assembly is sandwiched between the squeegee holder and the fixing nut member.

  According to this configuration, it is possible to switch the squeegee holder between the fixed state and the non-fixed state with respect to the squeegee mounting portion by one extremely simple operation such as the rotation operation (tightening or loosening) of the fixing nut member. Become.

  In addition, when adopting such a configuration as the fixing means, the mounting shaft of the squeegee holder in the squeegee mounting portion is a support shaft that rotatably supports the squeegee mounting portion with respect to the head. By being provided on the opposite side, it is preferable that the fixing nut member is positioned on the support shaft side in a state where the squeegee holder is assembled to the squeegee assembly portion. .

  According to such a configuration, while the diameter of the fixing nut member is increased to some extent to improve the operability, the portion, that is, the portion with a heavy weight is arranged on the support shaft side, It is possible to reduce the influence on the inertia when driving the squeegee.

According to the screen printing apparatus according to claims 1 to 4 , the squeegee can be easily and quickly attached to and removed from the head while the squeegee can be rotated (swinged) with respect to the head. Workability when changing the squeegee can be improved. In particular, according to the second and fourth aspects of the present invention, the squeegee (squeegee holder) can be fixed to and released from the head by one type of operation, so that the workability of attaching and detaching the squeegee to the head can be further improved.

  Embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show the configuration of the head portion of the screen printing apparatus according to the present invention. As shown in FIG. 1, the screen printing apparatus is supported by a traveling unit 2 that reciprocally moves along a mask sheet M superimposed on a substrate (not shown), and is movable up and down with respect to the traveling unit 2. It has a head 1 composed of an elevating unit 4, and slides along the surface of the mask sheet M in a state where a squeegee 31 described later is pressed against the mask sheet M at a predetermined angle and pressure by the operation of the head 1. In this way, paste such as cream solder or conductive paste supplied on the mask sheet by this sliding is expanded.

  The traveling unit 2 is provided so as to be able to travel in one direction (left and right in FIG. 1) along a rail that is not shown in the figure. For example, the traveling unit 2 is connected to a ball screw shaft that is rotationally driven using a motor as a drive source The ball screw shaft is configured to reciprocate along the rail in accordance with forward / reverse rotation driving of the ball screw shaft. In the following description, for the sake of convenience, the traveling direction of the traveling unit 2 will be referred to as the X-axis direction, and the direction orthogonal to this on the horizontal plane will be referred to as the Y-axis direction (illustrated in FIG. 1).

  The lifting / lowering unit 4 is attached to the lower end of the rod 3 connected to a lifting / lowering driving mechanism that uses a motor or air cylinder as a driving source mounted on the traveling unit 2. It is driven up and down.

  The elevating unit 4 holds the squeegee 31 for expanding the paste supplied on the mask sheet M. The squeegee 31 is integrally incorporated in the squeegee unit 30. Hereinafter, the squeegee unit 30 will be described in detail together with a specific configuration of the elevating unit 4.

  As shown in FIG. 1, the elevating unit 4 has a main frame 10 made of, for example, aluminum connected to the rod 3. A support portion 14 with a pressure sensor 12 such as a load cell interposed is suspended from the lower surface of the frame 10, and a sub-frame 16 is swingably supported by the support portion 14. Specifically, a first support shaft 15 extending in the X-axis direction protrudes from the support portion 14, and the sub-frame 16 is attached to the first support shaft 15 via a bearing or the like, so that the frame 16 is attached to the first support shaft 15. 1 is supported so as to be swingable around a support shaft 15.

  The subframe 16 is rotatably supported by a unit assembly member 18 corresponding to the squeegee assembly portion according to the present invention, and a drive mechanism for driving the unit assembly member 18 is mounted.

  As shown in FIG. 3, the unit assembly member 18 is a rectangular plate-like member that is elongated in the Y-axis direction. The unit assembly member 18 is rotated around the subframe 16 via a support portion 18a that is erected in the middle in the longitudinal direction. It is supported movably. Specifically, the second support shaft 17 extending in the Y-axis direction is supported by the subframe 16 in a state of being rotatable around the axis, and the unit assembly member 18 is supported by the second support shaft 17 via the support portion 18a. By mounting, the unit assembling member 18 is swingably supported with respect to the subframe 16.

  The second support shaft 17 that supports the unit assembling member 18 passes through the subframe 16 and protrudes to the opposite side, and a pulley 24 is attached to the protruding portion. A servo motor 22 as a drive source is fixed to the sub-frame 16, and a drive belt 26 is attached across the pulley 23 attached to the output shaft of the motor 22 and the pulley 24. The drive belt 26 is stretched by the tension pulley 28 being pressed from the outer peripheral side of the lever. That is, the servo motor 22, the pulleys 23, 24, 28, the drive belt 26, and the like constitute the drive mechanism, and the operation of the servo motor 22 causes the unit assembly member 18 to rotate forward and backward around the second support shaft 17. It is designed to be driven.

  A squeegee unit 30 is detachably attached to the unit assembly member 18. As shown in FIGS. 3 and 4, the squeegee unit 30 includes a squeegee 31 and a squeegee holder 32 that holds the squeegee 31.

  The squeegee holder 32 is an elongated plate member in the Y-axis direction made of a light alloy such as an aluminum alloy. On the other hand, the squeegee 31 is a rectangular plate-like member made of, for example, hard urethane or stainless steel and elongated in the Y-axis direction, and is held by the holder 32 in a state of being superimposed on the squeegee holder 32 as shown in FIG. .

  Of the squeegee holder 32, a surface 32a opposite to the surface on which the squeegee 31 is held is an assembly surface for the unit assembly member 18 (hereinafter referred to as an assembly surface 32a). On the assembly surface 32a, a pair of screw shafts 36 (screw shaft portions) are integrally projected at a predetermined interval in the Y-axis direction, and an operation nut 37 (fixed to the tip of these screw shafts 36 is provided. And the squeegee unit 30 is fixed to the unit assembly member 18 by these screw shafts 36 and the like as will be described later.

  At both ends in the longitudinal direction of the squeegee holder 32, side leakage prevention plates 34 are further provided. These lateral leakage prevention plates 34 are members for preventing the paste from flowing and leaking (running away) to the side of the squeegee 31 (the Y axis direction outer side) during the printing operation.

  As shown in FIGS. 1 and 5, the side leakage prevention plates 34 are a pair that approach each other from the base end portion toward the tip end portion (in FIG. 5, the upper portion to the lower portion) with a center line L (shown in FIG. 1) as a boundary. This is a substantially trapezoidal plate-like member having a sliding contact surface 34a, and is assembled on the center line L so as to be rotatable (swingable) at the end of the squeegee holder 32 with its base end as a fulcrum (rotation center). And is elastically held in a predetermined neutral position.

  More specifically, as shown in FIG. 5, the side leakage preventing plate 34 is formed with a through hole 34c penetrating in the thickness direction at the center of the base end portion, and a collar 39 is inserted into the through hole 34c. ing. Then, the fixing bolt 40 is inserted into the through hole 34c (collar 39) from the outside of the side leakage prevention plate 34, and further, the fixing bolt 40 is screwed into the screw hole 32b of the squeegee holder 32. A side leakage prevention plate 34 is assembled to the end of the squeegee holder 32 so as to be rotatable around the fixing bolt 40.

  Further, each lateral leakage prevention plate 34 has a base end portion (through hole 34c) formed by cutting a part of the outer surface side thereof, that is, the surface opposite to the assembly surface side with respect to the squeegee holder 32 in the thickness direction. A pair of contact surfaces 34b are formed which are spread evenly from the first portion toward the distal end. An urging member 38 having a pair of leaf spring pieces 38a extending in a substantially inverted V shape (inverted V shape in FIG. 5) is fixed to the squeegee holder 32, and each of the plates of the urging member 38 is The tip of the spring piece 38a is in contact with each contact surface 34b of the side leakage prevention plate 34 from both sides of the fixing bolt 40 as shown in FIGS. That is, in the state where no external force acts on the side leakage prevention plate 34, the elastic force of each leaf spring piece 38a acts on the side leakage prevention plate 34 evenly, whereby the squeegee 31 (work surface for expanding the paste). The side leakage prevention plate 34 is held at a position (hereinafter referred to as a neutral position) where the angle α (hereinafter referred to as the sliding contact surface angle α) formed between the squeegee contact surface 34a is equal, and the squeegee holder 32 is restrained. When an external force is applied only to the side leakage prevention plate 34, the side leakage prevention plate 34 rotates against the elastic force of the leaf spring piece 38a, and when this external force is removed, the elasticity of the leaf spring piece 38a The side leakage prevention plate 34 rotates in the opposite direction, and as a result, the side leakage prevention plate 34 is configured to return to the neutral position.

  In the present embodiment, the squeegee unit 30 is configured such that the sliding contact surface angle α is 70 ° in the state where the side leakage preventing plate 34 is in the neutral position as described above.

  The squeegee unit 30 as described above is assembled and fixed to the unit assembling member 18 by the operation nut 37 in a state of being superimposed on the unit assembling member 18.

  Specifically, a pair of notches 20 (notches) corresponding to the screw shafts 36 of the squeegee unit 30 are formed at both ends in the Y-axis direction of the unit assembly member 18 as shown in FIG. The squeegee unit 30 is superimposed on the lower surface (lower surface in FIG. 3) of the unit assembly member 18 through the assembly surface 32a in a state where each screw shaft 36 is inserted from the side with respect to the notch 20. The squeegee unit 30 is drawn into and fixed to the lower surface of the unit assembly member 18 by tightening the operation nut 37 in this state. In short, the squeegee unit 30 is fixed to the unit assembly member 18 by sandwiching the unit assembly member 18 between the operation nut 37 and the squeegee unit 30.

  The specific shape of the notch 20 of the unit assembling member 18 is such that, for example, the squeegee 31 is positioned so that the squeegee 31 is positioned in a state where the screw shaft 36 is abutted against the back end of the notch 20. Width, depth (guide depth) dimensions, etc. are set.

  Next, the function and effect of the screen printing apparatus as described above will be described.

  In this screen printing apparatus, preparation work for assembling the squeegee unit 30 to the unit assembling member 18 of the head 1 is performed prior to the start of work. This assembly is an operator task. In this case, the operator overlaps the unit assembly member 18 with the squeegee unit 30 while inserting each screw shaft 36 of the squeegee unit 30 into the notch 20 of the unit assembly member 18. Then, by tightening the operation nut 37 and fixing the squeegee unit 30 to the unit assembling member 18, the squeegee unit 30 can be easily and quickly assembled to the head 1. It is assumed that the substrate is already positioned at a predetermined reference position in a state where the mask sheet M is overlaid.

  When the preparatory work is completed, the head 1 is operated based on an operation input instruction for starting the work by the operator, whereby the printing work is started in the screen printing apparatus.

  Specifically, first, the squeegee 31 is disposed above a predetermined work start position by the operation of the traveling unit 2, and the squeegee unit 30 is rotationally displaced by the operation of the unit assembly member 18, for example, in FIG. When 31 moves to the right, the squeegee 31 is set in a state of being bent forward (acute angle) toward the traveling direction as indicated by a solid line in FIG. At this time, the squeegee 31 is set to the attack angle β during the printing operation. The attack angle β is a contact angle of the squeegee 31 with respect to the mask sheet M, that is, an inclination angle of the squeegee 31 with respect to the mask sheet M when the paste is expanded by bringing the squeegee 31 into contact with the mask sheet M (FIG. 6 (a)).

  Next, the squeegee 31 is set at a height position where the edge portion abuts on the contact point on the mask sheet M by the operation (lowering) of the elevating unit 4. At this time, the squeegee 31 is brought into pressure contact with the mask sheet M at a preset pressure by driving and controlling the elevating unit 4 based on the detection value by the pressure sensor 12.

  When the squeegee 31 is set to a height position in contact with the mask sheet M as described above, the side leakage preventing plate 34 is moved through the sliding contact surface 34a on one side as shown in FIG. 6A. In this embodiment, the side leakage prevention plate 34 is formed so as to be rotatable as described above. As a result, within a predetermined angle (in this embodiment, 40 ° to 70 °). If the attack angle β is any angle, the side leakage prevention plate 34 will appropriately come into contact with the mask sheet M without a gap. Specifically, for example, when the attack angle β = 70 °, the sliding contact surface angle α of the side leakage prevention plate 34 is “70 °” as described above, so that the squeegee 31 is brought into contact with the mask sheet M. As shown in FIG. 6A, the side leakage prevention plate 34 comes into contact with the mask sheet M while maintaining the neutral position. On the other hand, when attack angle β <sliding contact surface angle α, for example, when attack angle β = 60 °, 40 °, when squeegee 31 is brought into contact with mask sheet M, FIGS. 6 (b) and 6 (c). As shown in FIGS. 4A and 4B, the side leakage prevention plate 34 is rotationally displaced from the neutral position against the elastic force of the leaf spring piece 38a, and comes into contact with the mask sheet M in this state. In this case, the lateral leakage prevention plate 34 is pressed against the mask sheet M with respect to the mask sheet M by an elastic force corresponding to the bending of the leaf spring piece 38a.

  When the squeegee 31 is pressed against the predetermined contact point in this way, paste is supplied onto the mask sheet M by a supply device (not shown), and the squeegee 31 is moved in the X-axis direction by the operation of the traveling unit 2. By (forward movement), the paste on the mask sheet M is expanded by the squeegee 31. At this time, the lateral leakage prevention plate 34 prevents the lateral leakage of the paste, thereby appropriately expanding the paste.

  When the squeegee 31 reaches the end position, the tilting direction of the squeegee 31 is switched as shown by a two-dot chain line in FIG. The direction of the prevention plate 34 is switched. Then, after the squeegee 31 is set at a height position where it abuts on the contact point on the mask sheet M as described above, the squeegee 31 moves in the X-axis direction. 31. At this time, the side leakage prevention plate 34 is in pressure contact with the mask sheet M via the sliding surface 34a on the other side, that is, the sliding surface 34a on the side different from that at the time of forward movement. Side leakage will be prevented.

  Thereafter, the paste is expanded by reciprocating the squeegee 31 along the mask sheet M while reversing the direction of the squeegee 31 as described above, and as a result, the paste is applied to the substrate through the opening formed in the mask sheet M. Is applied (printed).

  When this reciprocation is repeated a predetermined number of times, the printing operation is completed, the squeegee 31 is reset to a predetermined home position, and a series of printing operations by the screen printing apparatus is completed.

  After the printing operation is completed, the squeegee unit 30 is replaced with one corresponding to the next production (next lot), that is, one holding the squeegee 31 corresponding to the next production as necessary. This work is the work of the operator as described above. In this case, the operator loosens the fixing bolt 40 of the squeegee unit 30 to release the fixed state with respect to the unit assembling member 18, and then into the notch 20. By pulling the squeegee unit 30 away from the unit assembly member 18 along the squeegee unit 30, the squeegee unit 30 can be easily and quickly detached from the head 1.

  As described above, in this screen printing apparatus, while the squeegee 31 is rotatably provided on the head 1, the drive mechanism including the servo motor 22, the pulleys 23, 24, 28, the drive belt 26, and the like as described above is used. Since the connected unit assembly member 18 is provided in the head 1 in advance, the squeegee unit 30 (that is, the squeegee holder 32 holding the squeegee 31) is detachably assembled to the unit assembly member 18. When the squeegee unit 30 is assembled to the head 1, there is no need for the troublesome work of connecting the holder to the rotational drive mechanism while assembling the squeegee unit (squeegee holder) to the head as in the prior art. Work such as replacement of the squeegee 31 can be performed easily and quickly.

  Therefore, while maintaining the advantages of this type of screen printing apparatus such as the degree of freedom in setting the angle of the squeegee 31 or the advantage of printing weight, it is possible to improve workability such as replacement of the squeegee 31. .

  In particular, in this screen printing apparatus, the unit assembly member 18 is provided with a notch 20, while the squeegee unit 30 is provided with a screw shaft 36 to which an operation nut 37 is screwed, and the screw shaft 36 is inserted into the notch 20. After the squeegee unit 30 is overlaid on the assembly member 18, the squeegee unit 30 can be assembled and fixed to the head 1 simply by tightening the operation nut 37, and the operation nut 37 is loosened and the squeegee unit 30 is assembled. Since the squeegee unit 30 can be detached from the head 1 simply by pulling it away from the member 18, no complicated work is required, and the operator can easily and quickly replace the squeegee unit 30. It can be performed.

  Further, in this screen printing apparatus, the assembly surface of the squeegee unit 30 in the unit assembly member 18 is on the side opposite to the second support shaft 17 that supports the unit assembly member 18 on the subframe 16, and the squeegee unit. Since the operation nut 37 is positioned on the second support shaft 17 side in the assembled state, the inertia during operation of the squeegee unit 30 is improved while improving workability such as replacement of the squeegee unit 30. There is also an effect that the influence on can be reduced. That is, in the above configuration, it is advantageous to improve the workability by providing the operation nut 37 with a certain diameter so that the operator can easily pick it. In this case, however, the operation nut 37 Therefore, there is a concern about the influence on the inertia when the squeegee unit 30 is operated (turned). However, according to the configuration of the embodiment as described above, since the operation nut 37 is located on the second support shaft 17 side of the unit assembly member 18, that is, the side close to the rotation center, when driving the squeegee unit 30. It is possible to effectively reduce the influence on the inertia of. Therefore, there is an advantage that the squeegee unit 30 can be driven quickly and accurately while reducing the influence on the inertia while improving workability by using a nut having a large diameter as the operation nut 37.

  The above-described screen printing apparatus is an example of the screen printing apparatus according to the present invention, and the specific configuration thereof can be appropriately changed without departing from the gist of the present invention.

  For example, in the above embodiment, the screw shaft 36 provided on the squeegee unit 30 is interposed in the notch 20 of the unit assembly member 18 and the operation nut 37 is fastened, whereby the squeegee unit 30 is attached to the unit assembly member 18. Of course, the squeegee unit 30 may be fixed in a configuration other than this. For example, the squeegee unit 30 is provided with an insertion portion having a U-shaped cross section, and the squeegee unit 30 is fixed to the unit assembly member 18 by using clamping means such as a toggle clamp with the unit assembly member 18 inserted into the insertion portion. You may comprise. In short, any configuration may be used as long as the squeegee unit 30 can be attached and detached with a simple operation. However, from the viewpoint of detaching the squeegee unit 30 more quickly, the squeegee unit 30 can be attached to the unit assembly member 18 as in the configuration using the operation nut 37 of the embodiment or the configuration using the clamp. It is preferable that the fixed state and the non-fixed state can be switched by one kind of operation.

  In this embodiment, the work surface of the squeegee 31, that is, the surface for pressing the paste is a flat surface, but may of course be a convex surface or a concave surface.

  In this embodiment, an example of a screen printing apparatus configured such that the work surface of the squeegee 31 (that is, the surface for expanding (pressing) the paste) is orthogonal to the rotational radius direction of the squeegee 31. Of course, as disclosed in Patent Document 1 of the prior art, the present invention is also applicable to a screen printing apparatus in which a squeegee is provided so that the work surface of the squeegee is substantially parallel to the rotational radius direction. .

  The operation of the screen printing apparatus described in the above embodiment is a basic operation of the apparatus, and the following printing operation may be performed as a more specific operation. In the following description, as shown in parentheses in FIGS. 2 and 6A, the upper and lower edges of the squeegee 31 are defined as a first edge 31a, and the other edge is defined as a second edge 31b. The work surface of the squeegee will be described with reference numeral 31c. For the sake of convenience, the presence of the side leakage prevention plate 34 is ignored.

  Based on FIG. 7 (a), when the squeegee 31 moves forward to the right (right in the figure), the work surface 31c is directed in the traveling direction (right) as shown by the solid line in FIG. While maintaining the attack angle β (β <90 °), the squeegee 31 is brought into pressure contact with the mask sheet M via the first edge 31a, and the squeegee 31 is moved along the mask sheet M in this state. When the moving end is reached, the squeegee 31 is lifted on the spot, and the squeegee 31 (work surface 31c) is driven by rotating the squeegee 31 about the second support shaft 17 (rotation center O in the figure). Invert. Specifically, the work surface 31c of the squeegee 31 is once rotated downward so as to face the mask sheet M and then face the opposite side (left side) (in the figure, it is rotated clockwise). After the height position of the second edge 31b becomes lower than the height position of the first edge 31a as the squeegee 31 rotates, the head 31 is lowered at a predetermined timing (a state indicated by a broken line in the figure) As a result, the second edge 31b of the squeegee 31 is brought into contact with the mask sheet M on the right side (the rear side in the traveling direction after reversal) by a distance L1 from the contact position of the first edge 31a at the end of forward movement. Then, the squeegee 31 is stopped at the timing when the attack angle β is reached while the squeegee 31 is further raised while being rotated to bring the second edge 31b into sliding contact with the mask sheet M. As a result, as shown by the two-dot chain line in the figure, that is, the attack angle β at the time of backward movement (after reversal) is equal to the attack angle β at the time of forward movement, and the mask sheet of the first edge 31a at the end of forward movement The squeegee 31 is inverted so that the second edge 31b of the squeegee 31 is located on the left side of the contact position with respect to M by the distance L0 (the virtual plane 50a connecting the rotation center O and the first edge 31a during forward movement, In addition, the inclination angle γ of the virtual plane 50b connecting the rotation center O and the second edge 31b during the backward movement with respect to the mask sheet M is 90 ° or more. That is, when the second edge 31b is brought into contact with the mask sheet M at a position on the right side of the paste pushed by the squeegee 31 at the end of the forward movement, the paste accumulated on the mask sheet after the inversion is not leaked. The squeegee 31 is positioned on the work surface 31c side. According to such a reversal operation, the paste is not dragged in the subsequent printing operation, and the printing operation can proceed favorably. In addition, since the rotation operation for raising and lowering the squeegee and the raising / lowering operation are performed in parallel, the switching time from the forward movement (reverse movement) to the backward movement (forward movement) can be shortened. Efficiency can be improved. When the amount of paste accumulated on the mask sheet is large, the distance L1 may be earned (taken longer) by moving the squeegee 31 to the right during the rotating operation.

  This operation is an example of a squeegee 31 having a rectangular cross section and a flat work surface 31c. For example, as shown in FIG. 7B, the squeegee unit 30 has a cross section in which the work surface 31c is recessed. It is also possible to employ a configuration in which a crescent moon type squeegee 31 is provided and the second support shaft 17 (rotation center O) is provided on the work surface 31c side to drive the squeegee 31 to rotate. The action can be performed.

  That is, based on the upper diagram in FIG. 7B, when the squeegee 31 moves to the right (right in the figure), the work surface 31c is directed in the traveling direction (right) and the attack angle β The squeegee 31 is moved along the mask sheet M in a state where the angle is 90 ° or more (the inclination angle γ of the virtual plane 50a connecting the rotation center O and the first edge 31a with respect to the mask sheet M is 90 ° or more). Then, when the moving end is reached, the squeegee 31 is raised on the spot, and the work surface 31c of the squeegee 31 once faces downward and faces the mask sheet M, and then turns to the opposite side (left side) around the rotation center O. The squeegee 31 is driven to rotate (in the same figure, rotated clockwise), and then the squeegee 31 is moved downward, as shown in the lower diagram (two-dot chain diagram) in FIG. The squeegee 31 is inverted so that the second edge 31b of the squeegee 31 contacts the right side (the rear side in the advancing direction after the inversion) from the contact position of the first edge 31a with the mask sheet M at a distance L0. The inverted attack angle β is less than 90 ° (the inclination angle γ of the virtual plane 50b connecting the rotation center O and the second edge 31b with respect to the mask sheet M is less than 90 °). In this manner, the crescent-shaped squeegee 31 with the concave work surface 31c also performs a good printing operation without dragging the paste after squeegee reversal, as in the case of the rectangular squeegee 31 described above. In addition, the efficiency of the printing process can be improved. If necessary, such as a large amount of paste, the distance L0 may be earned by moving the squeegee 31 to the right during the rotation.

  In the above description using FIGS. 7A and 7B, the operation when the squeegee 31 is switched from the forward movement to the backward movement has been described, but the operation when switching from the backward movement to the forward movement is basically performed. May perform the reverse operation of the above.

It is a side view which shows the head part of the screen printing apparatus which concerns on this invention. It is a perspective view which shows the raising / lowering unit of a screen printing apparatus. It is a perspective view of the raising / lowering unit which shows the state which removed the squeegee unit from the unit assembly | attachment member. It is a perspective view which shows the structure of a squeegee unit. It is a disassembled perspective view which shows the attachment structure of the side leakage prevention board in a squeegee unit. It is a schematic diagram which shows the positional relationship of the squeegee and side leakage prevention board at the time of a printing operation ((a) is an attack angle of 70 degrees, (b) is an attack angle of 60 degrees, (c) is an attack. The case where the angle is 40 ° is shown). It is a schematic diagram showing the positional relationship between the mask sheet and the squeegee in the squeegee moving direction switching operation ((a) is the case where the attack angle of the squeegee at the time of forward movement and the backward movement is both less than 90 °, (b) This shows the case where the attack angle of the squeegee at the time of forward movement is 90 ° or more and the attack angle at the time of backward movement is less than 90 °).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Head 2 Traveling unit 4 Lifting unit 18 Unit assembly member 20 Notch 22 Servo motor 30 Squeegee unit 31 Squeegee 34 Side leakage prevention plate 36 Screw shaft 40 Fixing bolt

Claims (4)

A squeegee is supported, and a head that relatively reciprocates the squeegee along the mask sheet superimposed on the substrate is provided. The squeegee is supported by the head so that the squeegee can rotate about an axis perpendicular to the moving direction. Screen printing device
The head is provided with a squeegee assembling portion which is provided so as to be rotatable around the axis and which can be driven to rotate around the axis by being connected to a rotation driving mechanism. The squeegee holder that holds the
The squeegee includes edge portions at both ends of a work surface that presses the paste, the work surface faces a traveling direction when the head is moved, and one of the edge portions is a mask sheet when the squeegee moves forward. And when the squeegee returns, the other edge portion is displaced by the operation of the rotary drive mechanism so as to contact the mask sheet. Once facing the mask sheet and facing the opposite side, the edge portion contacts the mask sheet, and this contact position is behind the contact position of the edge portion with respect to the mask sheet at the end of movement before the reversing operation. screen printing apparatus according to claim Rukoto the squeegee is arranged to be positioned. The screen printing apparatus according to claim 1,
As a fixing means for assembling and fixing the squeegee holder with respect to the squeegee assembling part, with respect to a fixed state in which the squeegee holder is fixed with respect to the squeegee assembling part based on one kind of operation and the squeegee assembling part A screen printing apparatus, characterized in that a fixing means is provided for switching to an unfixed state in which the squeegee holder can be removed. The screen printing apparatus according to claim 2,
The fixing means includes a screw shaft portion provided integrally with the squeegee holder, a fixing nut member screwed onto the tip of the screw shaft portion, and a screw nut portion provided on the squeegee assembly portion. A squeegee holder, and a squeegee holder formed by overlapping the squeegee holder on the squeegee assembly and tightening the fixing nut member with the screw shaft inserted into the notch. A screen printing apparatus, characterized in that the squeegee assembling part is sandwiched by a fixing nut member. The screen printing apparatus according to claim 3.
An assembly surface of the squeegee holder in the squeegee assembly is provided on the side opposite to the support shaft that rotatably supports the squeegee assembly with respect to the head, so that the squeegee holder is attached to the squeegee assembly. The screen printing apparatus is configured so that the fixing nut member is positioned on the support shaft side in a state in which the fixing nut member is assembled .

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