JP2013067043A - Screen printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen printing device capable of reducing disconnection of lines and missing sections in printing caused by air bubbles by achieving filling of ink without gaps into a pattern hole of a screen mask.SOLUTION: The screen printing device includes a squeegee 11, a printing stage 51, and a vibration source 61. By the squeegee 11 sliding on the upper surface of the screen mask 21, paste ink 41 is filled from the pattern hole 22 of the screen mask 21 disposed at the upper part of the printing stage 51, and further, the screen mask 21 is separated from a printing object 31 in order to perform printing on the printing object 31. The vibration source 61 connected to the underside of a board surface of the printing stage 51 generates transverse waves on the surface of the printing stage 51.

Description

  The present invention relates to a screen printing apparatus that performs gap printing, and more particularly to a screen printing apparatus having a mechanism for reducing disconnection or chipping of printing due to air bubbles.

Screen printing allows pattern formation with a relatively small number of processes, and is used in the manufacturing field of displays, mobile devices, solar cells, and the like. Moreover, since it corresponds also to a large area, the application to the wiring formation of a large display is anticipated.
In order to improve the quality of screen printing, it is necessary to supply paste ink onto the screen, accurately fill the pattern holes with the paste, and accurately transfer the paste in the pattern holes to the printing medium.

However, the existing technology focuses on individual parts such as screen masks, squeegees, and paste inks, and modification of individual materials. Improvement of individual parts and materials such as improvement of paste rheology, screen detachability, improvement of deformation, etc. It has been done mainly with partial improvements.
Due to the high quality of the members, the required printing technology has been increasing year by year from the miniaturization and thinning of the wiring pattern formed by screen printing, and it has become difficult to cope with it only by improving the parts and materials.
As a countermeasure, the technique disclosed in Patent Document 1 adopts a means for controlling printing pressure by changing a squeegee mechanism of a screen printing apparatus to stabilize printing.

JP 2004-098500 A

However, in the technique of Patent Document 1, since the squeegee mechanism becomes large and the screen mask is suppressed in a wide range, the pattern hole is covered, and air escape in the pattern hole is prevented during squeezing. Therefore, there is a problem that the print quality is deteriorated.
An object of the present invention is to provide a screen printing apparatus capable of reducing ink breakage and chipping caused by bubbles by realizing ink filling without gaps in the pattern holes of the screen mask.

  (1) In the present invention, the printing is performed by filling the pattern hole with ink by sliding a printing stage, a screen mask arranged on the upper part of the printing stage and having a pattern hole formed thereon, and sliding on the upper surface of the screen mask. What is claimed is: 1. A screen printing apparatus comprising: a squeegee for transferring to a substrate to be printed disposed on a stage; and the screen printing apparatus comprising at least one vibration source for vibrating the printing stage. .

(2) In this case, one of the vibration sources may be provided substantially at the center of the printing stage.
(3) The vibration source may be configured such that the frequency of vibration applied to the printing stage is any value in a range of 15 kHz to 25 kHz.
(4) In this case, the vibration source is characterized in that the amplitude of vibration applied to the printing stage is any value within a range of 40% to 80% of the particle size of the ink particles. May be.

(5) In this case, the upper surface of the printing stage is square, rectangular, or circular, and the length L and width W of the printing stage are half wavelengths of vibration applied to the printing stage. Where λ is an arbitrary integer n, m,
(N + 1/12) × λ ≦ L ≦ (n + 11/12) × λ,
(M + 1/12) × λ ≦ W ≦ (m + 11/12) × λ
It may be characterized by being in the relationship.

  According to the present invention, a minute gap is generated between the screen mask and the printing stage during printing by slightly vibrating the printing stage with the vibration source. This gap allows bubbles trapped in the pattern hole of the screen mask to go outside, and ink is filled into the pattern hole without any gap. By transferring this ink to the printing material, printing without disconnection or chipping can be realized.

It is the schematic which shows an example which looked at the cross section of the mode of the printing by the screen printing apparatus concerning one Embodiment of this invention from the side surface side. FIG. 5 is an enlarged cross-sectional view in which the periphery of a pattern hole is enlarged when the printing stage is not vibrated by a vibration source in the screen printing apparatus according to the embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view in which a periphery of a pattern hole is enlarged when a printing stage is vibrated by a vibration source in the screen printing apparatus according to the embodiment of the present invention. It is the expanded sectional view which expanded the circumference of the crevice between a screen mask and a printed matter in the screen printer concerning one embodiment of the present invention. It is a top view explaining arrangement of a vibration source in a screen printing device concerning one embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an example of a cross section of a printing state by the screen printing apparatus according to the present embodiment as seen from the side surface side. This screen printing apparatus includes a squeegee 11, a printing stage 51, and a vibration source 61. By sliding the upper surface of the screen mask 21 with the squeegee 11, the paste ink 41 is filled from the pattern holes 22 of the screen mask 21 arranged at the upper part of the printing stage 51, and the screen mask 21 is further separated from the printing material 31. Thus, printing is performed on the substrate 31. The vibration source 61 connected to the lower surface of the printing stage 51 generates a transverse wave vibration on the surface of the printing stage 51.

  2 is an enlarged cross-sectional view in which the periphery of the pattern hole 22 is enlarged when the vibration of the printing stage 51 is not performed by the vibration source 61 in the apparatus of FIG. This is a schematic diagram of an example in which the state in which the bubbles 71 are trapped in the pattern holes 22 is observed from a cross section. When the vibration of the printing stage 51 is not performed by the vibration source 61, there is no gap between the screen mask 21 and the substrate 31 when the paste ink 41 is transferred, and bubbles trapped in the paste ink 41. Since the escape path 71 disappears, the printing material 31 is not printed or disconnected.

  FIG. 3 is an enlarged cross-sectional view in which the periphery of the pattern hole 22 is enlarged when the printing stage 51 is vibrated by the vibration source 61 in the apparatus of FIG. That is, in the figure, bubbles 71 trapped in the pattern holes 22 when printing is performed by the screen printing apparatus are generated from the gap 81 between the screen mask 21 and the substrate 31 generated by the vibration of the printing stage 51. It is the schematic of an example which observed the trend which passes through from the cross section.

  Compared to the case where the vibration of the printing stage 51 is not performed by the vibration source 61 as shown in FIG. 2, in the screen printing apparatus of this embodiment, the screen stage 21 and the substrate are printed by vibrating the printing stage 51 by the vibration source 61. A gap 81 is created between 31 and the bubbles 71 can exit to the outside of the pattern hole 22. Thus, by letting out the bubbles 71 to the outside, the pattern hole 22 is filled with the paste ink 41 without any gaps, and it is possible to prevent the occurrence of chipping or disconnection when the paste ink 41 is transferred to the printing material 31.

  FIG. 4 is an enlarged sectional view in which the periphery of the gap 81 between the screen mask 21 and the substrate 31 is enlarged. The size of the paste ink particles 42 contained in the paste ink 41 is larger than the gap 81 between the screen mask 21 and the substrate 31 generated by the vibration of the printing stage 51. That is, it can be seen that the paste ink 41 can be prevented from oozing out of the gap 81 by making the size of the gap 81 smaller than the ink particle 42.

  An electrostrictive element is used for the vibration source 61, and the material is lead zirconate titanate. The dimension of the electrostrictive element decreases in inverse proportion to the drive frequency. In order to obtain mechanical vibration, a driving frequency of a certain level is required, and it is desirable that the frequency is about 10 kHz to 25 kHz. The area where the bubbles 71 are trapped is very small. In order to always obtain the gap 81 at an arbitrary location, it is desirable that the drive frequency is 15 kHz or more. From the above two points, the drive frequency is preferably 15 kHz to 25 kHz, although not limited to this.

  Further, the vibration propagates on the printing stage 51 as a wave centering on the vibration source 61. The vibration obtained on the printing stage 51 at this time is a composition of the traveling wave propagated from the vibration source 61 and the reflected wave reflected from the end of the printing stage 51, and the amplitude obtained by the phase of the traveling wave and the reflected wave. The size of is determined. When this phase is the same phase, a standing wave is generated on the printing stage 51, and peaks and troughs of amplitude appear in a certain place. Further, in the case of the reverse phase, since the traveling wave and the reflected wave work so as to cancel each other, vibration cannot be obtained. For this reason, in order to obtain a vibration having a uniform magnitude on the printing stage 51, it is necessary to shift the phase of the traveling wave and the reflected wave to some extent, and the adjustment can be made with the dimensions of the printing stage 51.

  The optimum dimensions of the printing stage 51 are “(n + 1/12) × λ ≦ L ≦, where the length dimension L and the width dimension W are the half wavelength λ of vibration applied to the printing stage and arbitrary integers n and m. It is desirable that (n + 11/12) × λ, (m + 1/12) × λ ≦ W ≦ (m + 11/12) × λ ″. In order to obtain uniform vibration, it is desirable that the vibration source 61 is located at least approximately in the center of the printing stage 51. Further, when a plurality of vibration sources 61 are installed, as shown in FIG. 5, one vibration source 61 is arranged in the approximate center of the printing stage 51, and the other vibration source 61 is a vibration source in the approximate center of the printing stage 51. It is necessary to install it at a position (on the dotted line in FIG. 5) at a distance P that is an integral multiple of half wavelength from 61.

  Next, when the amplitude of vibration obtained on the printing stage 51 is small, the gap 81 hardly occurs, so that the bubbles 71 cannot escape from the pattern holes 22. Conversely, if it is too large compared to the paste ink particles 42, the paste ink 41 will ooze out. Therefore, the amplitude of the vibration obtained on the printing stage 51 is preferably 40% to 80% of the particle size of the paste ink particles 42.

Specific examples of the paste ink particles 42 include particles made of silver, copper, an alloy of tin and silver, and the like. The particle size of the paste ink particles 42 is preferably 0.5 to 3 μm. In particular, in the case of particles made of an alloy of tin and silver, it is used at 10 to 20 μm.
Examples of the resin contained in the paste ink 41 include epoxy resins and acrylic resins, but are not particularly limited.

11 Squeegee 21 Screen Mask 22 Pattern Hole 51 Printing Stage 61 Vibration Source

Claims (5)

A printing stage;
A screen mask disposed on the printing stage and having a pattern hole formed thereon;
A squeegee that fills the pattern holes with ink by sliding on the upper surface of a screen mask and transfers the ink to a substrate to be placed on the printing stage;
In a screen printing apparatus comprising:
A screen printing apparatus comprising at least one vibration source for vibrating the printing stage.   The screen printing apparatus according to claim 1, wherein one of the vibration sources is provided at a substantially center of the printing stage.   The screen printing apparatus according to claim 2, wherein the vibration source has a vibration frequency applied to the printing stage having a value in the range of 15 kHz to 25 kHz.   4. The screen printing apparatus according to claim 3, wherein the vibration source has an amplitude of vibration applied to the printing stage within a range of 40% to 80% of a particle diameter of the ink particles. 5. . The printing stage has a square shape, a rectangular shape, or a circular shape on the upper surface, and the printing stage length L and width W are half integers of vibration applied to the printing stage, and any integer. If n and m,
(N + 1/12) × λ ≦ L ≦ (n + 11/12) × λ,
(M + 1/12) × λ ≦ W ≦ (m + 11/12) × λ
The screen printing apparatus according to claim 4, wherein:

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