JP4241497B2 - Screen printing apparatus and screen printing method - Google Patents

Description

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

Known methods for soldering electronic components include solder bumps and solder pre-coating. In this method, a solder bump as a solder protruding electrode or a solder precoat as a solder film is formed on a workpiece electrode such as an electronic component or a substrate for solder bonding. Screen printing is widely used as a solder supply method in these solder formation processes. In this method, cream solder is printed on the upper surface of the workpiece through pattern holes provided in the mask plate. In this screen printing operation, squeezing for moving the squeegee is followed by plate separation for separating the substrate from the lower surface of the mask plate. In the plate separation operation, the substrate is separated from the mask plate by lowering the substrate while supporting the lower surface of the mask plate by a clamp member that sandwiches the substrate from both sides at the printing position (see, for example, Patent Document 1).
JP-A-7-214748

  By the way, finer electronic components have been developed in recent years, and the pitch of electrodes formed on a workpiece has been reduced, and a large number of electrodes are arranged with high density. A mask plate used for forming bumps on these electrodes has a greatly reduced mask thickness as compared with that used for solder printing on a conventional printed circuit board. However, when a screen printing method conventionally used is applied as it is to screen printing performed using a mask plate having a thin mask thickness for a work on which such high-density electrodes are formed, the following will be described. Challenges arise.

  In order to ensure good print quality in screen printing, not only the filling ability to reliably fill the pattern holes with cream solder, but also the cream solder from the pattern holes when separating the plate that separates the mask plate from the workpiece after filling. It is required that the stencil separation property is good without separating the mold. However, with the increase in the density of the electrodes and the reduction in the thickness of the mask, the degree of printing difficulty increases, and in particular, it is very difficult to ensure uniform and good plate release properties over the entire surface of the workpiece.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a screen printing apparatus and a screen printing method that can ensure good plate release properties.

The screen printing apparatus of the present invention is a screen for printing a paste on a substrate through the pattern hole by bringing the substrate into contact with the lower surface of the mask plate on which the pattern hole is formed and sliding a squeegee on the upper surface of the mask plate. A printing apparatus, which receives the substrate and holds it at a printing position on the lower surface side of the mask plate, and carries the substrate in the first direction to carry the substrate into the substrate holding portion for printing. A substrate transport unit composed of a pair of transport rails that can be moved up and down by a transport unit lifting mechanism for unloading a subsequent substrate from the substrate holding unit, and a substrate held by the substrate support unit and in contact with the lower surface of the mask plate. And a plate separating means for separating the substrate from the second direction perpendicular to the first direction and the substrate held by the substrate holding part. A clamp member for supporting the lower surface of the mask plate in outer position in the second direction side of the substrate in the plate separating time to spaced from the lower surface of the mask plate does not interfere with the conveyance of the substrate in the substrate transfer unit, and the It is disposed a pair of conveying rails top, and a mask deflection preventing member for supporting a lower surface of the mask plate in outer position in the first direction side of the substrate during the detaching, vertically to preventing member flexing the mask A long groove penetrating in the direction is provided, the conveyance rail on the fixed side and the mask deflection preventing member are fixedly fastened by bolts, and the conveyance rail on the movable side penetrates the bolt through the long groove, and the conveyance rail on the movable side Is moved in the second direction in accordance with the width dimension of the substrate, the bolt is slid in the long groove .

The screen printing method of the present invention is a screen for printing a paste on a substrate through the pattern hole by bringing the substrate into contact with the lower surface of the mask plate in which the pattern hole is formed and sliding the squeegee on the upper surface of the mask plate. A printing method, a substrate carrying-in step of carrying a substrate to be printed in a first direction by a substrate carrying unit and carrying it into a substrate holding unit, and sandwiching the substrate from a second direction orthogonal to the first direction by a clamp member And a mask mounting step in which the lower surface of the mask plate is relatively brought into contact with the substrate, the clamp member, and the mask deflection preventing member disposed at the outer position on the first direction side of the substrate. And a squeegee for printing paste on the substrate through the pattern holes by sliding a squeegee on the upper surface of the mask plate A step, while supporting the lower surface of the mask plate by the clamping member and the mask deflection preventing member, to separate the substrate from the lower surface of the mask plate, thereafter, by lowering the substrate transport unit, said clamping member And a plate separating step of separating the mask deflection preventing member from the lower surface of the mask plate.

According to the present invention, by providing the mask deflection preventing member that abuts the lower surface of the mask plate at the outer position on the substrate transport direction side, the mask plate is mounted on the four sides of the substrate together with the clamp member that sandwiches the substrate from the transport orthogonal direction. A state in which the downward bending of the mask plate is supported by supporting from the lower surface side , that is, the mask plate is surrounded by the clamp member on the two sides in the first direction (X direction) around the substrate in contact with the lower surface. With respect to the two sides in the two directions (Y direction), the mask deflection preventing member can be used to release the plate in the state where the outer position in each direction is supported from the lower surface, and the good plate release property over the entire surface of the substrate. Can be secured.

  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 plan view of the screen printing apparatus according to an embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to an embodiment of the present invention. FIG. 4 is an explanatory view of the support state of the mask plate in the screen printing apparatus according to the embodiment of the present invention. FIGS. 5 and 6 are operation explanatory views of the screen printing apparatus according to the embodiment of the present invention. It is.

  First, the structure of the screen printing apparatus will be described with reference to FIGS. In FIG. 1, the substrate positioning unit 1 is configured by stacking substrate holding units 5 on a moving table including a Y-axis table 2, an X-axis table 3, and a Z-axis table 4. A substrate holding surface for adsorbing and holding the substrate 6 is provided on the upper surface of the substrate holding unit 5. The substrate holding unit 5 receives the substrate 6 and prints on the lower side of the mask plate of the screen printing unit described later. Hold in position.

  By controlling the driving of the Y-axis table 2 and the X-axis table 3, the substrate 6 held by the substrate holding part 5 can be moved in the X direction and the Y direction to adjust the position of the substrate 6 during screen printing. it can. Further, by controlling the driving of the Z-axis table 4, the substrate 6 held by the substrate holding unit 5 can be raised and lowered to an arbitrary height position.

  A pair of transport rails 7 are horizontally disposed above the substrate positioning unit 1, and the transport rails 7 transport the substrate 6 received from the upstream side to the substrate positioning unit 1 in the X direction (first direction). To do. And the board | substrate 6 after printing by the screen printing part 10 mentioned later in the board | substrate positioning part 1 is similarly carried out downstream by the conveyance rail 7. FIG. That is, the transport rail 7 serves as a substrate transport unit that transports the substrate 6 in the X direction, thereby loading the substrate 6 into the substrate holding unit 5 and unloading the printed substrate 6 from the substrate holding unit 5.

Each of the paired transport rails 7 includes a clamp member 8, and the clamp member 8 on one side is coupled to the moving rod 9 a of the clamp drive mechanism 9 and is movable in the horizontal direction. In a state where the moving rod 9a protrudes, the clamp member 8 is at a position away from the side end portion of the substrate 6 and is in a clamp release state. When the movable rod 9a returns, the movable clamp member 8 moves in the Y direction (second direction) as indicated by the arrow a, and the side end of the substrate 6 held by the substrate holding part 5 is moved. Clamp the end face from both sides. The transport rail 7 can be moved up and down by a transport unit lifting mechanism (not shown), and the substrate 6 clamped by the clamp member 8 can be brought into contact with the lower surface of the mask plate 12 during a printing operation.

  A screen printing unit 10 is disposed above the substrate positioning unit 1. The screen printing unit 10 has a configuration in which a squeegee unit 13 is disposed above a mask plate 12 which is extended on a rectangular holder 11 and provided with a plurality of pattern holes 12a. The squeegee unit 13 has a configuration in which a squeegee 16 can be moved up and down by two squeegee lifting mechanisms 15 arranged vertically on a horizontal base 14, and is reciprocated in the Y direction by a squeegee moving mechanism (not shown). .

  The substrate 6 is aligned with the mask plate 12 by the substrate positioning unit 1 and abuts against the lower surface of the mask plate 12. In a state where the substrate 6 is in contact with the lower surface of the mask plate 12, cream solder as a paste is supplied onto the mask plate 12, and the squeegee 16 is brought into contact with the upper surface of the mask plate 12 and is slid. The solder paste is printed through the pattern holes 12a on the surface. In this screen printing operation, the substrate 6 is clamped from both sides by the clamp member 8, and the horizontal position is maintained.

  As shown in FIG. 2, two long plate-shaped mask deflection preventing members 17 are positioned at the front and rear ends of the clamp member 8 in the X direction on the transport rail 7 to clamp the height level of the upper surface. Attached to the upper surface of the member 8. The mask deflection preventing member 17 is located on the upper surface of the transport rail 7 so as not to hinder the transport operation of the substrate 6 by the transport rail 7. That is, the clamp member 8 and the mask deflection preventing member 17 are coupled to the two transport rails 7 arranged in the X direction in the substrate transport unit 5.

The mask deflection preventing member 17 is provided with a long groove 17a penetrating in the vertical direction in a substantially majority range of the entire length so that the position in the width direction of the transport rail 7 on the movable side (right side in FIG. 1) can be changed. . 3A shows a cross section taken along the line AA in FIG. 2, and the mask deflection preventing member 17 is fixedly fastened to the conveying rail 7 on the fixed side (left side in FIG. 1) by bolts 18 and is movable. The transport rail 7 is held in a state where bolts 18 are passed through the long grooves 17a and only the vertical direction of the transport rail 7 is restricted. When the movable-side transport rail 7 is moved in the Y direction according to the width dimension of the substrate 6, the bolt 18 is slid in the long groove 17a.

  FIG. 3B shows the height direction positions of the clamp member 8 and the mask deflection preventing member 17 when the printing operation is performed on the substrate 6 held by the substrate holding unit 5 by the screen printing unit 10. . In this printing operation, the substrate holding unit 5 holding the substrate 6 by the Z-axis table 4 is raised, and the conveyance rail 7 is raised by the conveyance unit elevating mechanism, whereby the clamp member 8 and the mask deflection preventing member 17 are masked. It contacts the lower surface of the plate 12.

  As a result, as shown in FIG. 4, the mask plate 12 is surrounded by the clamp member 8 for two sides in the X direction and the mask deflection preventing member 17 for two sides in the Y direction around the substrate 6 in contact with the lower surface. The outer position in each direction is supported from the lower surface. The printing operation by the screen printing unit 10 is performed in this supported state. The plate separating operation for separating the substrate 6 from the lower surface of the mask plate 12 after the printing operation is performed by lowering the substrate holding portion 5 by the Z-axis table 4 while the mask plate 12 is supported as shown in FIG.

  That is, in the above configuration, the Z-axis table 4 serves as a plate separating means for separating the substrate 6 held by the substrate holding portion 5 and contacting the lower surface of the mask plate 12 from the lower surface of the mask plate 12. The clamp member 8 sandwiches the substrate 6 held by the substrate holding unit 5 from the Y direction orthogonal to the X direction, and also separates the substrate 6 from the lower surface of the mask plate 12 at the time of separating the plate 6 on the Y direction side of the substrate 6. The lower surface of the mask plate 12 is supported at the outward position. Further, the mask deflection preventing member 17 is disposed at a position that does not interfere with the transport of the substrate 6 in the substrate transport section 5 and supports the lower surface of the mask plate 12 at the outer position on the X direction side of the substrate 6 when the plate is separated.

  In FIG. 4, when the size of the target substrate 6 in the X direction is smaller than the length of the clamp member 8, the mask plate 12 is supported between the mask deflection preventing member 17 and the substrate 6 from below. An unsupported area (area C indicated by a chain line) is generated. In this case, the planar shape of the mask deflection preventing member 17 is formed according to the size of the substrate 6 so as to cover the area C (for example, a shape provided with a protrusion toward the substrate side), and is exchanged according to the substrate 6. By doing so, the unsupported area can be eliminated as much as possible.

  Next, a screen printing operation by the screen printing apparatus will be described with reference to FIGS. 5 and 6, the state of each part in the BB cross section of FIG. 2 is shown on the left side from the center line, and the state of each part in the AA cross section of FIG. 2 is shown on the left side. First, as shown in FIG. 5A, the substrate 6 to be printed is transported in the first direction by the transport rail 7 and transported to the substrate holder 5 of the substrate positioning unit 1 (substrate transporting step), and then the Z-axis. The substrate holding portion 5 is raised by the table 4 and comes into contact with the lower surface of the substrate 6 to receive the substrate 6.

  Thereafter, as shown in FIG. 5B, the substrate holding portion 5 is further raised by the Z-axis table 4 so that the upper surface of the substrate 6 is flush with the upper surfaces of the clamp member 8 and the mask deflection preventing member 17. The both end faces of 6 are clamped by being clamped by the clamp member 8 from the Y direction (clamping process). Next, as shown in FIG. 5C, the transport rail 7 is raised by the transport unit lifting mechanism, and the lower surface of the mask plate 12 is arranged at the outer position on the X direction side of the substrate 6, the clamp member 8, and the substrate 6. Relative contact with the provided mask deflection preventing member 17 (mask mounting step). As a result, the mask plate 12 is supported from the lower surface side in the support arrangement shown in FIG. 4 in plan view.

  In this state, as shown in FIG. 6A, the squeegee 16 is slid on the upper surface of the mask plate 12 to print the cream solder 19 on the substrate 6 through the pattern holes 12a (squeezing step). Next, release is performed. That is, as shown in FIG. 6B, the substrate holding part 5 is lowered by the Z-axis table 4 while the lower surface of the mask plate 12 is supported by the clamp member 8 and the mask deflection preventing member 17, and the substrate holding part 5. The substrate 6 adsorbed and held on the upper surface is separated from the lower surface of the mask plate 12 (plate separation step), and the substrate 6 is placed on the transport rail 7.

  Then, as shown in FIG. 6C, the conveyance rail 7 is lowered to separate the clamp member 8 and the mask deflection preventing member 17 from the lower surface of the mask plate 12, and then the printed substrate 6 is moved to the conveyance rail. 7 is carried out to the downstream side, and a series of screen printing operations for one substrate 6 is completed.

In the above-described screen printing operation, the mask plate 12 is in a supporting state as shown in FIG. 4 , that is, the mask plate 12 is around the substrate 6 in contact with the lower surface, the two sides in the X direction are clamped by the clamp member 8, and With respect to the two sides in the Y direction, the mask is prevented from being released by the mask deflection preventing member 17 in a supported state in which the outward positions in the respective directions are supported from the lower surface, so that the substrate is brought into contact with the lower surface of the mask plate 12. It is possible to prevent a problem caused by “sticking to the mask”, which is likely to occur when the upper surface of the substrate 6 and the lower surface of the mask plate 12 are separated from each other.

  That is, in general, in the state after squeezing, the upper surface of the substrate and the lower surface of the mask plate are stretched not only by the cream solder in the pattern holes but also by the cream solder that oozes between the upper surface of the substrate and the lower surface of the mask plate. At the start of the plate separation operation, the mask plate tends to be bent downward by being pulled by the substrate. Then, when the amount of deflection of the mask plate reaches a certain limit and the restoring force to return the deflection to the original state exceeds the adhesive force between the mask plate and the substrate, the upper surface of the substrate is removed from the lower surface of the mask plate. Leave.

  If the amount of deflection is large at this time, the state when the cream solder is removed from the pattern hole is not uniform over the entire surface of the mask plate. Prone to printing defects. For this reason, it is desirable to support the lower surface of the mask plate 12 at a position as close as possible to the outer edge of the substrate 6 for the purpose of suppressing the bending of the mask plate at the time of separating the plate as much as possible.

  In the present embodiment, as described above, at the outer positions in the four sides of the substrate 6, that is, for the two sides in the X direction, by the clamp member 8, and for the two sides in the Y direction, by the mask deflection preventing member 17. Since the lower surface of the mask plate 12 is supported, it is possible to suppress the bending of the mask plate 12 when the plate is released as much as possible. Thereby, even when the target is a substrate on which fine pitch electrodes are formed at a high density, a uniform and good plate release property can be ensured over the entire surface of the substrate.

  INDUSTRIAL APPLICABILITY The screen printing apparatus and the screen printing method of the present invention have the effect of ensuring good plate release properties, and are useful for the field of printing pastes such as cream solder and conductive paste on a substrate. .

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 partial sectional view of a screen printing apparatus according to an embodiment of the present invention. Explanatory drawing of the support state of the mask plate in the screen printing apparatus of one embodiment of this invention Operation explanatory diagram of a screen printing apparatus according to an embodiment of the present invention Operation explanatory diagram of a screen printing apparatus according to an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate positioning part 5 Board | substrate holding | maintenance part 6 Board | substrate 7 Conveying rail 8 Clamp member 10 Screen printing part 12 Mask plate 12a Pattern hole 13 Squeegee unit 16 Squeegee 17 Mask deflection prevention member

Claims (3)

  A screen printing apparatus for printing a paste on a substrate through the pattern hole by bringing the substrate into contact with the lower surface of the mask plate in which the pattern hole is formed and sliding a squeegee on the upper surface of the mask plate, A substrate holding unit that receives the substrate and holds it at a printing position on the lower surface side of the mask plate, and the substrate is carried into the substrate holding unit by transporting the substrate in the first direction, and the printed substrate is transferred from the substrate holding unit. A substrate transport unit composed of a pair of transport rails that can be moved up and down by a transport unit lifting mechanism for unloading, and a plate separating means for separating the substrate held by the substrate holding unit and contacting the lower surface of the mask plate from the lower surface of the mask plate; The substrate held by the substrate holding part is sandwiched from a second direction orthogonal to the first direction, and the substrate is separated from the lower surface of the mask plate. A clamping member that supports the lower surface of the mask plate at an outer position on the second direction side of the substrate when the plate is released, and does not interfere with the conveyance of the substrate in the substrate conveyance unit, and on the upper surfaces of the pair of conveyance rails And a mask deflection preventing member that supports the lower surface of the mask plate at an outer position on the first direction side of the substrate when the plate is separated, and the mask deflection prevention member has a long groove penetrating in the vertical direction. The fixed-side conveyance rail and the mask deflection preventing member are fixedly fastened by bolts, and the movable-side conveyance rail passes the bolts through the long grooves, so that the movable-side conveyance rail has the width of the substrate. Accordingly, when moving in the second direction, the screen printing apparatus is characterized in that the bolt is slid in the long groove.   The clamp member and the mask deflection preventing member are coupled to the pair of conveyance rails arranged in the first direction in the substrate conveyance section, and the clamp member and the mask deflection prevention member are moved by raising the conveyance rail. The screen printing apparatus according to claim 1, wherein the screen printing apparatus is in contact with a lower surface of the mask plate. A screen printing method for printing a paste on a substrate through the pattern hole by bringing the substrate into contact with the lower surface of the mask plate on which the pattern hole is formed and sliding a squeegee on the upper surface of the mask plate, A substrate carrying step of carrying the substrate in the first direction by the substrate carrying portion and carrying it into the substrate holding portion, a clamping step of clamping the substrate from a second direction orthogonal to the first direction by a clamp member, A mask mounting step of bringing the lower surface of the mask plate into contact with the mask, the clamp member, and a mask deflection preventing member disposed at an outer position on the first direction side of the substrate; and a squeegee on the upper surface of the mask plate. A squeezing step of printing a paste on the substrate through the pattern holes by sliding the The mask deflection preventing member is spaced the substrate while supporting the lower surface of the mask plate from the lower surface of the mask plate, thereafter, by lowering the substrate transport unit, the clamp member and the mask deflection preventing member said A screen printing method comprising: a plate separating step of separating from a lower surface of the mask plate.

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