JP2008155557A - Printing method and printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to print with high precision and reproducibility without imparting stress on a printed board or others with warps. <P>SOLUTION: A mask 3 is secured to a mask frame 4 with slight slack. The mask frame 4 is mounted on the base 7 being positioned by guide pins 7b and clamped by a clamp mechanism 5 fixed to the side faces of the base 7. In this case, pushing and pressing elastic members 6 arranged in the forward end portion of the clamp mechanism 5 push the upper face of the mask to eliminate the slack of the same. The board 1 is mounted on a stage 2 by being positioned by the guide pins 2a. The stage 2 is raised and the upper face of the board 1 comes into contact with a mask face during printing. In that condition, printing is carried out by running a squeegee (not shown). In this case, printing is carried out with the mask brought into close contact with the board. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing method and a printing apparatus, and more particularly to a printing method and a printing apparatus suitable for screen-printing a solder paste on a printed board using a printing mask and a squeegee.

In the mounting process, the solder paste is screen-printed on the printed circuit board, but the printed circuit board on which the printing is performed is often warped. When printing on a printed circuit board with warping, the pattern cannot be printed with high accuracy and the separation of the plate becomes non-uniform. Conventionally, printing has been performed so as to correct warping as much as possible. It was. For example, in the method disclosed in Patent Document 1, the mask is attracted by a magnet to correct the warping of the printed circuit board. FIG. 5 is a cross-sectional view showing the printing method disclosed in Patent Document 1. As shown in FIG. The printed circuit board 11 having warpage is placed on a suction stage 12 capable of vacuum suction. An electromagnet 10 is embedded in the suction stage 12. A metal mask 13 fixed to the mask frame 14 is disposed above the printed circuit board 11. In printing, first, the printed circuit board 11 is vacuum-sucked by the suction stage 12. Next, while the electromagnet 10 is turned on and the mask 13 is attracted, the mask 13 is pressed with a squeegee to print cream solder. Finally, the electromagnet 10 is turned off and the printed board 11 is removed from the suction stage 12.
Japanese Patent Laying-Open No. 2004-230871 (paragraph [0011], FIG. 1)

  As in the prior art described above, in order to correct the warpage of the substrate by attracting the metal mask with a magnetic force, a very large magnetic force is required, leading to an increase in the size of the apparatus. In particular, when electromagnet suction and vacuum suction are used together on the same stage as in Patent Document 1, the apparatus becomes complicated. In addition, when the warpage of the substrate is forcibly corrected, a large stress is generated inside the printed circuit board, and the internal wiring of the substrate may be cut. Furthermore, during the plate separation operation, there is a problem that the gap rapidly increases at the edge of the substrate, and uniform printing conditions cannot be provided within the substrate surface.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and the object of the present invention is firstly to avoid the increase in size and complexity of the apparatus and without causing stress on the substrate. This is to make the separation uniform and perform printing accurately.

In order to achieve the above object, according to the present invention, in a printing method for printing a required pattern on a substrate using a mask and a squeegee on which the required print pattern is formed, the mask is directed to the substrate. A printing method is provided, in which printing is performed while applying a tension of 2 to a region of the mask where the print pattern is not formed.
Preferably, the substrate has a warp, and printing is performed without correcting the warp and in a state where the mask is in close contact with the substrate.

In order to achieve the above object, according to the present invention, a stage for holding a substrate that is a substrate to be printed, a mask on which a required printing pattern is formed, a mask frame for holding the mask, and the mask frame A clamping mechanism for holding the base plate on the base, wherein the pressing member is elastic and has a pressing member that applies tension downward to the upper surface of the mask. Is provided.
Preferably, the mask is held on the mask frame with a certain amount of slack and warpage.

  According to the present invention, screen printing is performed while applying tension to the mask from above with an elastic pressing member. According to this configuration, when the mask and the substrate are brought into contact prior to printing, if the substrate is warped, the mask is deformed and the substrate and the mask are brought into contact with each other over a wide area. When the squeegee is pressed against the mask and moved, the mask can follow the warpage of the substrate even if the substrate warps due to the expansion and contraction of the elastic member and the elastic deformation of the mask. Printing is performed in a close contact state. Then, printing is performed while the substrate is warped, and no special correction force acts on the substrate, so that damage to the substrate and disconnection of the internal wiring are prevented. In the printing apparatus according to the present invention, only the pressing member for applying tension to the mask is simply added, so that the above effect can be enjoyed without increasing the size and complexity of the apparatus. Further, when printing is finished, the plate separation is performed by moving the stage that can move in the vertical direction downward, so that it is possible to maintain high uniformity of plate separation within the substrate surface.

Next, the best mode for carrying out the invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a printing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the mask 3 is fixed to the mask frame 4. At this time, it is desirable that the mask 3 is fixed to the mask frame 4 with a slight slack. A print pattern portion 3a is provided at the center of the mask 3, and a pattern to be printed is opened here. The mask frame 4 is pressed onto the base 7 by the clamp mechanism 5 at two locations on the short side. The base 7 is a member having a substantially U-shaped planar shape, and is screwed to the apparatus main body (not shown) through openings 7a provided at the four corners. A plate-like pressing elastic member 6 is fixed to the inner front end portion of the clamp mechanism 5, and the pressing elastic member 6 presses the mask 3 downward from above. As a result, the mask is held without sagging. A region between the clamp mechanisms 5 excluding the print pattern portion 3a of the mask 3 is a free running region of a squeegee for allowing the mask and the solder to become familiar. In the present invention, since the pressing elastic member 6 installed in the clamp mechanism 5 is located in the blank portion of the idle running region on the mask 3, the apparatus does not increase in size by providing this member.

  2 to 4 are side views for explaining the operation of the printing apparatus according to the embodiment of the present invention. FIG. 2 shows a state in which the clamp mechanism 5 is opened, and FIG. 3 shows the mask frame 4 in the clamp mechanism. FIG. 4 shows the clamped state and the state at the time of printing. As shown in FIG. 2, the clamp mechanism 5 is roughly constituted by three elements, that is, a main body 5a, a handle 5b, and an attachment portion 5c. The main body 5a and the handle 5b are connected via a link 5d. Further, the main body 5a and the attachment portion 5c are rotatably connected via a support shaft 5e, and the handle 5b and the attachment portion 5c are rotatably connected via a support shaft 5f. The attachment portion 5 c is screwed to the side surface of the base 7. The pressing elastic member 6 is sandwiched between the main body 5a and the holding plate 5g, and the holding plate 5g is screwed to the main body 5a. A fixing pin 5h for fixing the mask frame 4 is provided on the lower surface of the main body 5a.

  Guide pins 2a are installed on the stage 2, and the substrate 1 is positioned by bringing the substrate 1 into contact with the guide pins 2a and the illustrated guide pins 2a. A guide pin 7b is installed on the base 7, and the mask frame 4 is positioned by bringing the mask frame 4 into contact with the guide pin 7b shown in the drawing and the illustrated guide pin 7b. In this way, the horizontal positioning of the substrate 1 and the mask frame 4 is achieved. In the state shown in FIG. 2, the mask 3 still has slack.

  When the handle 5b of the clamp mechanism 5 is rotated in the direction of the arrow from the state shown in FIG. 2, the main body 5a connected via the link 5d is also rotated, and the fixing pin 5h is masked as shown in FIG. The mask frame is sandwiched between the base 7 and the clamp mechanism 5 in contact with the upper surface of the frame 4. Thereby, the vertical position of the mask frame 4 is determined. At the same time, the tip of the pressing elastic member 6 comes into contact with the mask 3 and presses it downward. As a result, the slack generated in the mask 3 is removed. At this stage, the mask 3 and the substrate 1 are observed by a camera (both not shown) installed between the mask 3 and the stage 2 and connected to the image processing apparatus to confirm alignment. When a position shift is detected, for example, the stage 2 is moved in a horizontal plane to perform alignment. The camera may be installed on the mask. Further, the alignment may be performed by observing with a stereomicroscope.

Subsequently, as shown in FIG. 4, the stage 2 is raised to bring the substrate 1 into contact with the mask 3. At this time, the mask 3 is curved in accordance with the curved surface of the warped substrate 1. In the printing apparatus of the present invention, when the substrate 1 is in close contact with the mask 3, it is pressed using the elasticity of the mask without correcting the warp of the substrate 1, and the contact pressure between the mask 3 and the substrate 1 is It is determined by the pushing-up force of the stage 2 and the restoring force of the pressing elastic member 6 that opposes the force. At this time, the positions of the stage 2 and the mask 3 are determined so as not to give stress to the substrate. The stage 2 is installed on a vertical movement mechanism (not shown), and the vertical movement of the stage 2 is performed using this. Then, while pressing the squeegee ₈₁ on the mask surface is moved in the right direction in the figure, or while pressing the squeegee ₈₂ on the mask surface are moved leftwards in the figure performs printing. At the time of printing at the left and right ends of the substrate 1 in the drawing, the substrate surface and the mask are brought into close contact with each other by the expansion and contraction of the pressing elastic member 5 and the elastic deformation of the mask 3. The pressing force of the squeegee at the time of printing is not strong enough to correct the warping of the substrate, and printing is performed while the substrate is warped, so that no great stress is applied to the inside of the substrate during printing. After printing, the stage 2 is lowered. At this time, plate separation occurs. However, since the substrate and the mask are in contact with each other over a wide area immediately before the stage starts to descend, the uniformity of plate separation can be kept high within the substrate surface. After the stage is lowered, the printed substrate 1 is removed and replaced with another substrate. Then, printing is continued by the same procedure.

  In the above-described embodiment, two clamp mechanisms are provided and each hold a pressing elastic member. However, a clamping mechanism is installed on each side of the mask frame so that each pressing elastic member is held. May be. In the above-described embodiment, it is suitable when the substrate is warped along two opposite sides, but when the substrate is also warped along a side perpendicular to the two sides (the substrate is bowl-shaped). In the case of warping), the adhesion between the mask and the substrate decreases. For such a substrate, it is possible to improve the adhesion of the mask to the substrate by providing four clamp mechanisms and applying tension to the mask along the four sides by the pressing elastic member.

In the above description, it is assumed that the substrate is warped in a convex shape, but according to the present invention, the same effect can be obtained even when the substrate is warped in a concave shape. However, in order to prevent the substrate from rolling on the stage, it is necessary to take measures such as changing the shape of the guide pins for positioning the substrate or arranging a spacer under the substrate.
In the above-described embodiment, the pressing elastic member 6 is held by the clamp mechanism. However, it is not always necessary to do so. For example, the pressing elastic member 6 may be installed on the metal frame 4 or the base 7. As the pressing elastic member, an elastic resin, a spring, a cylinder, an absorber, or the like can be used.
The present invention can be advantageously applied to printing of solder paste, but is not limited to this, and can also be applied to printing of other materials such as conductive paste.

1 is a perspective view showing a printing apparatus according to an embodiment of the present invention. FIG. 6 is a side view (part 1) illustrating the operation of the printing apparatus according to the embodiment of the present invention. FIG. 6 is a side view (part 1) illustrating the operation of the printing apparatus according to the embodiment of the present invention. FIG. 6 is a side view (part 1) illustrating the operation of the printing apparatus according to the embodiment of the present invention. Sectional drawing of the conventional printing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Stage 2a Guide pin 3, 13 Mask 3a Print pattern part 4, 14 Mask frame 5 Clamp mechanism 5a Main body 5b Handle 5c Attachment part 5d Link 5e, 5f Spindle 5g Holding plate 5h Fixing pin 6 Pressing elastic member 7 Base 7a Opening 7b Guide pins 8 ₁ and 8 ₂ Squeegee 10 Electromagnet 11 Printed circuit board 12 Suction stage

Claims (13)

In a printing method for printing a required pattern on a substrate using a mask and a squeegee on which the required print pattern is formed, the print pattern of the mask is not formed with tension in the direction toward the substrate. A printing method comprising printing while adding to an area. The printing method according to claim 1, wherein the substrate has warpage, and printing is performed without correcting the warpage. The printing method according to claim 1, wherein the substrate has warpage, and printing is performed without correcting the warpage and in a state where the mask is in close contact with the substrate. The printing method according to claim 1, wherein the tension applied to the mask is applied along two opposite sides of the mask or along four sides of the mask. The printing method according to claim 1, wherein the pattern to be printed is a solder paste pattern. In a printing apparatus having a stage for holding a substrate to be printed, a mask on which a required printing pattern is formed, a mask frame for holding the mask, and a clamp mechanism for holding the mask frame on a base, elastic And a pressing member for applying a downward tension to the upper surface of the mask. The printing apparatus according to claim 6, wherein the mask is held on the mask frame with a certain amount of slack. The clamp mechanism is installed along two sides orthogonal to the running direction of the squeegee of the mask frame to clamp the mask frame, and the pressing member is installed in each clamp mechanism. The printing apparatus according to claim 6 or 7. 8. The clamp mechanism according to claim 6, wherein the clamp mechanism is installed along four sides of the mask frame to clamp the mask frame, and the pressing member is installed in each clamp mechanism. Printing device. The printing apparatus according to claim 6, wherein a guide pin that abuts the mask frame is installed on the base. The printing apparatus according to claim 6, wherein a guide pin that abuts the substrate is installed on the stage. The printing apparatus according to claim 6, wherein the stage is supported by a vertical movement mechanism so as to be movable up and down.   The printing apparatus according to claim 6, wherein a camera connected to an image processing apparatus is installed between the mask and the stage or above the mask.

Images