JP5247088B2 - Screen printing squeegee - Google Patents

Description

  The present invention relates to a squeegee used for screen printing for printing solder on a printed circuit board in order to mount electronic components on the printed circuit board.

  Conventionally, screen printing is used as a method for printing a printing agent such as cream solder on a printed circuit board in a process of mounting electronic components. In this method, a screen mask having pattern holes opened in accordance with a printing target part is set on a printed circuit board, and cream solder or the like is supplied onto the screen mask and a squeegee is slid to pass through the pattern holes. Cream solder or the like is printed on a printed board. In this method, cream solder is filled in pattern holes by moving the squeegee horizontally on the screen mask, and the cream solder is printed on a printed circuit board set on the lower surface of the screen mask. As this squeegee, the cream solder is scraped by a plate-like member inclined in the traveling direction, and the cream solder is pressed against the mask plate as the squeegee moves to fill the pattern hole with the cream solder. Are known.

  Here, when sliding the squeegee, the cream solder rolls (rolls over) and moves over the screen mask to fill the pattern hole so that it fills the pattern hole. It is known that this is a good method that can fill the pattern holes evenly. For this purpose, it is required to tilt the squeegee forward in the direction of travel. In this regard, in the conventional metal squeegee, by extending the downward projecting length, the squeegee is greatly curved when printing pressure is applied, so that an appropriate inclination angle is given to the portion in contact with the cream solder. However, since the force escapes due to the bending, a large printing pressure cannot be applied and the scraping ability of the cream solder is lowered. Conversely, if the protruding length is shortened, it is possible to apply a large printing pressure, so that the scraping performance is improved, but it is necessary to incline greatly in order to obtain an inclination angle. The distance with the upper cream solder approaches. For this reason, cream solder adheres to the squeegee holder, and when the squeegee is lifted, the solder that is attached is lifted together, and the cream solder is extracted from the pattern holes, or the lifted cream solder hangs down and is printed. There was a risk of defects.

Therefore, for example, the squeegee shown in Patent Document 1 has been considered. This is composed of a thick first squeegee part and a second squeegee part provided at the tip of the first squeegee and formed thinner than the first squeegee part, and the elastic coefficient of the second squeegee part is It is set smaller than the elastic coefficient of the first squeegee portion. By pressing with a squeegee in which two squeegees having different elastic coefficients are combined, cream solder is printed at an appropriate printing pressure on the entire surface of the printed circuit board which is bent and deformed.
Japanese Patent Laid-Open No. 8-111282

  However, in the thing of the said patent document 1, since the edge part of a 2nd squeegee part is thin, when big printing pressure is applied, this edge part will deform | transform into a pattern hole according to the hollow of a pattern hole, and will be filled There is a risk of scraping the applied cream solder. Further, even in a urethane squeegee having a low elastic modulus, there is a fear that the cream solder once filled is scraped out for the same reason.

  The present invention has been made in view of the above-described conventional problems, and is to provide a squeegee for screen printing that can ensure a high scraping property while rolling a printing agent with a small printing pressure.

In order to solve the above-mentioned problem, the constitutional feature of the invention according to claim 1 is that a screen printing squeegee for printing cream solder on a printed circuit board through a pattern hole by sliding on a screen mask. And a plate-like squeegee main body portion that is disposed forwardly inclined in the advancing direction at the time of sliding and extends in a direction perpendicular to the advancing direction, and a lower end portion of the squeegee main body portion in the advancing direction. Provided on the opposite side and formed thinner than the squeegee main body, extending in the longitudinal direction of the squeegee, and formed at the lower end of the strip-shaped recess to be thicker than the belt-shaped recess, A contact edge portion extending in a direction and contacting the upper surface of the screen mask, and when the contact edge portion slides on the screen mask, the belt-like recess portion Incrementally curvature than boundary di main body, with the opposite side of the traveling direction of the belt-shaped recess comes into contact with the solder cream, the said contact edges to fill the cream solder into the pattern holes of the screen mask It is characterized by inclining at an angle suitable for the above.

In a screen printing squeegee that prints cream solder on a printed circuit board through a pattern hole by sliding on the screen mask, the screen printing squeegee is arranged to be inclined forward in the traveling direction when sliding, A plate-like squeegee main body extending in a perpendicular direction, a lower end portion of the squeegee main body and provided on the opposite side of the advancing direction, and having a thickness thinner than the squeegee main body, and a squeegee longitudinal direction A strip-shaped recess extending to the bottom of the strip-shaped recess, and a contact edge that is formed thicker than the strip-shaped recess and extends in the longitudinal direction of the squeegee and contacts the upper surface of the screen mask, The squeegee main body, the strip-shaped recess, and the contact edge are all made of stainless steel.

  According to the first aspect of the present invention, since the band-like recess is formed thinner than the squeegee body, it is curved and tilts forward at a larger angle than the squeegee body, and slides without applying a large printing pressure. When the cream solder is inclined at an angle suitable for rolling, the filling ability of the cream solder to be appropriately pushed into the pattern hole of the screen mask can be improved. And since the contact edge is formed thicker than the band-shaped recess, the lower end is not easily deformed and does not deform according to the pattern hole, so that the cream solder is not scraped out without entering the pattern hole. Further, since the contact edge retains its original straight shape and is not easily deformed, it is possible to improve the scraping ability to evenly scrape the cream solder placed on the flat screen mask.

  According to the invention according to claim 2, since the stainless steel forming the screen printing squeegee is a high-rigidity material, the thick squeegee main body part is only slightly bent and deformed, and the pressing force does not escape. The scraping performance can be improved by efficiently transmitting the force to the lower part. Moreover, it can be set as an inexpensive printing squeegee without rusting.

  An embodiment of a squeegee for screen printing according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of a screen printing machine using a screen printing squeegee, and FIG. 2 is a front view of the screen printing squeegee.

  The screen printing machine 2 includes a substrate transport device (not shown) that transports the printed circuit board 4 in the X-axis direction, which is the transport direction, a substrate support device 6 that supports the printed circuit board 4 at a printing position, and a mask holder that holds the screen mask 8. 10 and a squeegee device 12.

  The substrate transport device is provided with a pair of guides (not shown) extending in the transport direction of the printed circuit board 4, and a conveyor belt (not shown) is annularly arranged on each of these guides. These conveyor belts are stretched around pulleys (not shown), and these pulleys are connected to a drive motor (not shown). The printed circuit board 4 is conveyed by circulating the conveyor belt. The operation of the drive motor is controlled by an operation control device (not shown). The space between the guides can be adjusted according to the size of the printed circuit board 4 to be conveyed.

  A printing position is defined slightly above the downstream side of the substrate transport apparatus. At this printing position, a substrate support device 6 is provided, and the substrate support device 6 is provided with a substrate support table (not shown) on which the printed circuit board 4 is placed. The substrate support is moved up and down by a lifting device (not shown). A clamp device (not shown) is provided at the tip of a guide (not shown) of the substrate transport apparatus, and the clamp device includes a pair of clamp members (not shown). One of the clamp members is fixed to be a fixed clamp member, and the other is movable as a movable clamp member in the Y-axis direction perpendicular to the X-axis direction. The printed circuit board 4 is transported by a substrate transport device and stopped by a stopper (not shown) (corresponding to the printing position). Then, the printed circuit board 4 is moved from the substrate transport device and comes into contact with the screen mask 8 while being clamped by the clamp device at a printing position on the substrate support.

  As shown in FIG. 1, the mask holding table 10 supports the screen mask 8 and a holding frame 16 fixed to the periphery thereof. The mask holding base 10 is a rectangular frame, on which a holding frame 16 is placed and positioned and fixed.

  The screen mask 8 is a so-called combination mask including a metal portion made of a metal such as copper, stainless steel, and nickel and a mesh portion that is easily elastically deformed on the outer periphery thereof. The screen mask 8 is provided with pattern holes 18 for printing the surface of the printed circuit board 4 at positions corresponding to the printing positions. A paste-like cream solder 20 is supplied onto the screen mask 8 from a solder supply device (not shown).

  As shown in FIG. 1, the squeegee device 12 includes a slide 22, a first lifting device 24 and a second lifting device 26 held by the slide 22, and a first lifting device 24 held by the first lifting device 24. A printing squeegee 30, a second printing squeegee 32 held by the second lifting device 26, and a slide feeding device 34 that sends the slide 22 in the Y-axis direction are provided. The slide feeding device 34 includes a servo motor 36 and a ball screw mechanism 38 as drive sources. The rotation of the servo motor 36 is converted into a linear motion by the ball screw mechanism 38, and the slide 22 is moved in the Y-axis direction. It is done. The servo motor 36 is controlled by the operation control device. The movement of the slide 22 includes guide rails 40 extending in the Y-axis direction on both sides of the slide 22 and guide blocks (not shown) that are respectively fixed to both side surfaces of the slide 22 and are fitted to the guide rails 40 so as to be relatively movable. And will be guided by.

  A frame 42 having a gate shape with a pair of side walls and a top wall is fixed to the slide 22. On the frame 42 fixed to the slide 22, the first lifting device 24 and the first printing squeegee 30, the second lifting device 26 and the second printing squeegee 32 are moved in the moving direction of the squeegee device 12. It is provided symmetrically with respect to a plane orthogonal to (sliding direction). The lifting devices 24 and 26 and the printing squeegees 30 and 32 have the same configuration, and the first lifting device 24 and the first printing squeegee 30 will be described as representative examples.

  As shown in FIG. 1, the first elevating device 24 includes a cylinder portion 44 in which air is enclosed and a piston portion 46 that slides in the cylinder portion 44 by the pressure of the enclosed air. A guide rod 48 is fixed to the lower end portion of the piston portion 46, and the guide rod 48 is slidably fitted to a guide cylinder 50 erected on the slide 22 to guide the raising and lowering of the first printing squeegee 30. It is supposed to be. The cylinder portion 44 communicates with an air pump (not shown) via an air hose (not shown), and air supply is controlled by a solenoid valve (not shown) provided in the middle of the air hose. The solenoid valve is controlled by the operation control device.

  The first printing squeegee 30 includes a squeegee main body 54, a belt-like recess 56, and a contact edge 58, and is assembled to the lower part of the first lifting / lowering device 24 by a squeegee holding member 52. The squeegee holding member 52 is detachably connected to the lower end portion of the guide rod 48 by a butterfly screw or the like. The squeegee holding member 52 is formed of a long material extending in a direction (X-axis direction) perpendicular to the sliding direction of the first printing squeegee 30, and the squeegee holding member 52 includes the first printing squeegee 30. Is detachably fixed by bolts or the like. As shown in FIGS. 2 and 3, the squeegee main body 54 of the first printing squeegee 30 is made of, for example, a rectangular plate made of stainless steel, and the squeegee holding member 52 causes the squeegee sliding direction to be perpendicular to the squeegee sliding direction. And is tilted forward in the direction of travel when sliding. A strip-shaped recess 56 thinner than the squeegee body 54 is provided at the lower end of the squeegee body 54, and the strip-shaped recess 56 is located on the opposite side of the traveling direction when the squeegee 30 slides on the screen mask 8. It is provided so as to extend in the longitudinal direction. A contact edge 58 formed thicker than the band-shaped recess 56 is provided at the lower end of the band-shaped recess 56. The contact edge 58 is provided straight along the lower end of the belt-like recess 56, and the contact edge 58 comes into contact with the surface of the screen mask 8. The printing squeegees 30 and 32 are integrally formed by a squeegee main body 54, a belt-like recess 56 and a contact edge 58.

  The operation of the screen printing machine 2 configured as described above will be described below with reference to the drawings. When the paste-like cream solder 20 is printed on the printed circuit board 4 as a printing agent using the screen printing machine 2 in the present embodiment, the screen mask 8 is positioned on the mask holder 10 to which the screen mask 8 is fixed, The cream solder 20 is placed on the screen mask 8 from the solder supply device.

  In the squeegee device 12, the slide 22 is positioned at one end in the Y-axis direction in the printing area of the screen mask 8, and the first printing squeegee 30 and the second printing squeegee 32 are both positioned at the rising end. Is done. Then, the printed circuit board 4 is carried in by the substrate transport device, is raised by the substrate support device 6, and is positioned and held at a printing position where it contacts the lower surface of the screen mask 8.

  Subsequently, the electromagnetic valve is opened, the first printing squeegee 30 is lowered by the first lifting device 24, and the lower end (contact edge portion 58) of the first printing squeegee 30 is placed on the upper surface of the screen mask 8. It will be in contact. At this time, the second printing squeegee 32 is still held at the rising end. Subsequently, the servo motor 36 is driven to move the slide 22 in the Y-axis direction (left direction in FIG. 1) as shown in FIG. 1, and the first printing squeegee 30 and the second printing squeegee 32 are moved. Move in the Y-axis direction. At this time, as shown in FIG. 4, the lower end portion of the first printing squeegee 30 slides in contact with the surface of the screen mask 8, and the cream solder 20 placed on the screen mask 8 is pushed into the pattern holes 18. Then, printing is performed on the surface of the printed circuit board 4.

  At the time of printing, according to the screen printing squeegee (first printing squeegee 30) having the above-described configuration, the band-shaped recess 56 is formed thinner in the first printing squeegee 30 than in the squeegee main body 54. Therefore, the bending is gradually increased from the boundary with the squeegee main body 54 where the bending stress to the band-shaped recess 56 acts greatly. Therefore, as shown in FIG. 4, the strip-shaped concave portion 56 is inclined forward at a larger angle than the squeegee main body portion 54, and the contact edge portion 58 rolls when the solder paste 20 slides without applying a large printing pressure. It is possible to improve the filling property that the cream solder 20 is appropriately pushed into the pattern holes 18 of the screen mask 8 by being inclined at an appropriate angle. The angle formed with the surface of the screen mask 8 is, for example, about 60 degrees for the squeegee body 56 (about 30 degrees as the forward tilt angle), and 40 degrees to 50 degrees for the contact edge 58 (forward tilt angle). As 50 degrees to 40 degrees). As shown in FIG. 6, the contact edge 58 is formed thicker than the band-shaped recess 56, so that the lower end portion does not deform according to the pattern hole 18, so that the contact edge 58 does not enter the pattern hole 18. The cream solder 20 is not scraped off. Further, since the contact edge portion 58 maintains its original straight shape and is difficult to deform, as shown in FIG. 6, the contact edge portion 58 has a scraping property for evenly scraping the cream solder 20 placed on the flat screen mask 8. Can be improved.

Further, since the stainless steel forming the printing squeegee 30 is a high-rigidity material, the thick squeegee body 54 is only slightly bent and deformed, and the pressing force does not escape due to the bending. Can be transmitted downward. Since the belt-like recess 56 is formed thin, it is easily elastically deformed by the transmitted pressing force, and the contact edge 58 is inclined forward to an angle suitable for rolling the cream solder 20 (for example, 40 to 50 degrees). Therefore, the filling property can be improved. At the same time, although it is curved and deformed, it is a high-rigidity material, so that it is possible to transmit a pressing force for reliably scraping off by its elastic force. Further, the contact edge portion 58 is a highly rigid material having a thickness and remains straight and does not deform so much, so that the cream solder 20 can be evenly scraped along the flat surface of the screen mask 8. Further, it can be provided as an inexpensive printing squeegee without rusting.
In the above embodiment, the width of the band-shaped recess is wider than that of the contact edge. However, the width of the contact edge is not limited to this, as shown in FIG. It may be widely formed.
The printing squeegee is not limited to stainless steel, and may be, for example, an aramid fiber reinforced plastic.

The perspective view which shows the outline | summary of the screen printer concerning this invention. The front view of a squeegee. A side view of a squeegee. The figure which shows a printing process. The figure which shows a printing process. The figure which shows a printing process. The figure which shows another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Screen printer, 4 ... Printed circuit board, 8 ... Screen mask, 12 ... Squeegee device, 18 ... Pattern hole, 20 ... Cream solder, 30 ... Screen printing squeegee (first printing squeegee), 54 ... Squeegee body , 56... Strip-shaped recess, 58.

Claims (2)

In a squeegee for screen printing that prints cream solder on a printed circuit board through pattern holes by sliding on the screen mask,
A plate-like squeegee main body portion that is disposed to be inclined forward in the advancing direction when sliding, and extends in a direction perpendicular to the advancing direction;
A belt-shaped recess that is provided at the lower end of the squeegee main body and on the opposite side of the traveling direction, is formed thinner than the squeegee main body, and extends in the squeegee longitudinal direction;
A contact edge that is formed at the lower end of the strip-shaped recess to be thicker than the strip-shaped recess, extends in the longitudinal direction of the squeegee and contacts the upper surface of the screen mask;
Have
When the contact edge slides on the screen mask, the band-shaped recess gradually curves from the boundary with the squeegee main body, and the traveling direction side opposite to the band-shaped recess contacts the solder paste. The screen printing squeegee is characterized in that the contact edge portion is inclined at an angle suitable for filling the pattern hole of the screen mask with cream solder. In a squeegee for screen printing that prints cream solder on a printed circuit board through pattern holes by sliding on the screen mask,
A plate-like squeegee main body portion that is disposed to be inclined forward in the advancing direction when sliding, and extends in a direction perpendicular to the advancing direction;
A belt-shaped recess that is provided at the lower end of the squeegee main body and on the opposite side of the traveling direction, is formed thinner than the squeegee main body, and extends in the squeegee longitudinal direction;
A contact edge that is formed at the lower end of the strip-shaped recess to be thicker than the strip-shaped recess, extends in the longitudinal direction of the squeegee and contacts the upper surface of the screen mask;
A squeegee for screen printing, wherein the squeegee main body, the strip-shaped recess, and the contact edge are all made of stainless steel.

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