Roughened printing screen

Abstract

A screen printing plate comprises a screen frame and screen cloth. The screen cloth is arranged in the screen frame and comprises a metal plate, and the metal plate is provided with a scraper face and a pasting and printing face. The surface of the blade surface is roughened to have an average roughness of between 20 nm and 5 [mu] m.

Description

Technical Field

[0001] The present disclosure relates to a printing screen, and in particular to a printing screen that has been roughened. Background Art

[0002] Screen printing has a wide range of applications, even in today's high-tech electronics industry, where it can be found in a variety of processes, including solar cells, semiconductor components, and IC substrates. With the rapid development of electronic products, screen printing technology for electronic circuits requires advanced screen design to accommodate the increasingly small and precise electronic components and enable rapid manufacturing.

[0003] The printing screen mainly consists of a screen frame and a mesh. It is known that an emulsion layer is coated on the mesh, and a pattern opening is set on the emulsion layer to allow printing paste (such as ink) to pass through the mesh, so as to print a pattern with the same shape as the pattern opening on the printed object. In detail, when printing, the printing paste is placed on the mesh, and the mesh is pressed down and moved back and forth by a scraper on the printing machine to achieve the printing function. Because the printing paste has both solid and liquid properties, when it is squeezed by the scraper, the printing paste will deform and flow, and be squeezed through the pattern opening of the screen to be printed on the printed object. When the printing paste is squeezed by the scraper on the mesh, a certain degree of friction is generated between the printing paste and the mesh, causing the deformation and flow of the printing paste on the mesh to produce a rolling effect. This helps the printing paste to smoothly enter the pattern opening, so that the ink penetration during printing can be further increased to print a fuller pattern.

[0004] Some known meshes are made with interlaced knots of yarns in the warp and weft. Because the knotted mesh possesses a certain tension, when the squeegee presses down on the screen, the knotted mesh can disperse the downward vertical force, preventing deviation during printing and reducing the occurrence of printed line expansion. However, due to the interlaced knots in the pattern openings of these screens, the ink penetration during printing is affected, resulting in an incomplete printed pattern. Furthermore, the uneven structure of the warp and weft interlaced in the mesh can cause uneven thickness of the printing paste applied to the substrate, resulting in an undulating printed pattern and affecting print quality. Therefore, screen printing has developed non-woven yarn meshes made from flat metal plates (e.g., steel plates or electroformed plates) to achieve a fully open screen without interlaced knots in the pattern openings. Summary of the Invention

[0005] However, the metal plate's surface is smooth. When the scraper presses down on the mesh, the low friction of the metal plate causes the printing paste to move faster and less frequently on the scraper's surface. This makes it difficult for the printing paste to enter the pattern openings, resulting in reduced ink penetration. When printing finer line widths, excessively fast printing paste movement can result in poor ink penetration through the mesh, leading to broken lines. Therefore, when printing with meshes such as metal plates, modifying the printing paste's rheological properties to achieve the desired ink penetration conditions is a key issue in screen printing technology.

[0006] One technical approach disclosed herein provides a printing screen. The printing screen comprises a screen frame and a screen cloth. The screen cloth is disposed within the screen frame. The screen cloth comprises a metal plate having a scraper surface and a printing surface. The scraper surface is roughened to have an average roughness between 20 nm and 5 μm.

[0007] In one embodiment, the material of the metal plate is selected from the group consisting of stainless steel, nickel alloy, titanium alloy, copper alloy, cobalt alloy, magnesium alloy and aluminum alloy.

[0008] In one embodiment, the roughening process is one of sandblasting, grinding, chemical etching, and laser processing, or a combination of two or more.

[0009] In one embodiment, the scraper surface includes a plurality of concave portions.

[0010] In one embodiment, the scraper surface has unidirectional scratches.

[0011] With the printing screen disclosed herein, the roughness and rolling properties of the mesh scraper surface of the printing screen are improved, so that the printing paste can roll more easily on the metal plate, achieving a better ink application effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a top view of a printing screen according to an embodiment of the present disclosure.

[0013] Figure 2 A side cross-sectional view of a printing screen according to an embodiment of the present disclosure is shown.

[0014] The reference numerals are as follows:

[0015] 100: Screen

[0016] 110: Screen frame

[0017] 120: Mesh

[0018] 130: Metal version

[0019] 131: Scraper surface

[0020] 132: Printing surface

[0021] 140: Graphic opening

[0022] A-A': hatching line DETAILED DESCRIPTION

[0023] The following embodiments are described in detail with reference to the accompanying drawings, but the specific embodiments described are only used to explain the present invention and are not used to limit the present invention. The description of the structural operation is not used to limit the order of its execution. Any structure recombined by the elements to produce a device with equal efficacy is within the scope of the disclosure of the present invention. The directional terms mentioned in the present invention, such as "upper" and "lower", etc., are only with reference to the directions of the accompanying drawings. Therefore, the directional terms used are only used to illustrate and understand the present invention, not to limit the present invention. In addition, the drawings are only used for schematic illustration and are not drawn according to their actual size.

[0024] The terms used throughout the specification and claims generally have their ordinary meanings in the art, in the context of this disclosure, and in the specific context, unless otherwise noted. Certain terms used to describe the present disclosure are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present disclosure.

[0025] See also Figure 1 , Figure 1 A top view of a printing screen 100 according to an embodiment of the present disclosure is shown. The printing screen 100 is, for example, rectangular, but not limited thereto. The printing screen 100 can be formed by fixing a mesh 120 on a screen frame 110, wherein the mesh 120 includes a metal plate 130, and the metal plate 130 has a graphic opening 140 for the printing paste (not shown) to pass through. The screen printing 100 presses the mesh 120 with a scraper (not shown) to squeeze the printing paste through the graphic opening 140, thereby printing the shape of the graphic opening 140 on the printed object (not shown). It should be understood that the present disclosure does not limit the scope, shape, quantity, etc. of the graphic opening 140. Figure 1 The graphics are designed for illustrative purposes only. Furthermore, the metal plate 130 can be made of stainless steel, nickel alloy, titanium alloy, copper alloy, cobalt alloy, magnesium alloy, aluminum alloy, or a composite material of multiple materials, depending on actual needs.

[0026] Please see next Figure 2 , Figure 2 The printing screen 100 of one embodiment of the present disclosure is shown according to Figure 1Side view of the middle section line A-A'. The two sides of the metal plate 130 are respectively: a scraper surface 131 in contact with the scraper, and a printing surface 132 in contact with the printed object. As previously mentioned, if a mesh made of a metal plate is used for printing, the smooth surface will cause the printing paste to move too fast on the scraper surface and lack rolling, resulting in the printing paste not being easy to enter the pattern opening, thereby causing problems such as reduced ink filling and incomplete printed graphics. Therefore, the present disclosure performs a roughening treatment on the scraper surface 131 of the metal plate 130, so that the rolling properties of the printing paste on the scraper surface 131 during printing are increased, thereby making it easier for the printing paste to enter the pattern opening 140 and achieve a better ink filling effect. Among them, in order to achieve good rolling properties of the printing paste during printing, in one embodiment, the surface of the scraper surface 131 is roughened to have an average roughness (Arithmetic Average Roughness) between 20nm and 5μm. The average roughness is the arithmetic mean of the absolute values ​​of the surface height deviations measured relative to a mean plane in the profile curve of the rough surface. The roughening treatment disclosed herein can be achieved through various methods, such as sandblasting, laser treatment, chemical etching, or grinding. The principles of these various methods are briefly described below to provide a clearer understanding of this disclosure.

[0027] First, sandblasting involves using fine abrasive particles to impact the scraper surface 131 of the metal plate 130, creating granular recesses on the scraper surface 131. Laser irradiation involves stimulating atoms, causing electron transitions and releasing radiation energy to generate a coherent, enhanced photon beam, which then irradiates the scraper surface 131. Laser irradiation can cause heating or photochemical reactions. Heating removes material through processes such as melting and vaporization, while photochemical reactions involve the material absorbing photon energy, disrupting its lattice structure and / or breaking its molecular bonds, causing some of the material on the scraper surface 131 to separate from the bulk, thereby removing the material and creating recesses. Chemical etching utilizes various media to chemically degrade the scraper surface 131, creating recesses. Lapping utilizes abrasive particles, creating scratches on the scraper surface 131 through the relative motion of the lapping tool and scraper surface 131 under a certain pressure.

[0028] As described above, in one embodiment, the roughening process can be performed by, for example, sandblasting, laser etching, or chemical etching, thereby producing a plurality of recesses on the scraper surface 131 by striking or eroding. Alternatively, in another embodiment, the roughening process can be performed by grinding to create scratches on the scraper surface 131. Preferably, the present disclosure can be achieved by producing, for example, unidirectional scratches. It should be noted that the roughening process described in the present disclosure is performed by sandblasting, grinding, chemical etching, or laser etching, or by a combination of two or more of these processes, so that the scraper surface 131 has an average roughness of 20 nm to 5 μm.

[0029] In detail, in the embodiments of the present disclosure, the measurement of roughness can be achieved, for example, by an atomic force microscope (AFM). The atomic force microscope uses the atomic force between the instrument tip and the measured object to cause the cantilever beam to produce a micro displacement to measure the surface morphology of the sample. In addition, it should be understood that the roughness disclosed in the present disclosure is expressed as an average roughness, which is only a way to express the degree of surface undulation of the scraper surface 131. There are also various measurement methods such as "maximum height roughness" and "root mean square roughness (RMS)", which can be used to define the size and change of the sample roughness. Therefore, the use of average roughness as an expression unit in the present disclosure is only for the purpose of explaining and understanding the present invention. Technicians in the field of the present disclosure can also use other measurement methods to express the same technical features of the present disclosure.

[0030] Continuing from the previous embodiment, in a preferred embodiment, when the average roughness of the scraper surface 131 of the printing screen 100 is between 20nm and 5μm, the printing paste can achieve the best rheological properties during printing and obtain the best ink penetration effect. Please refer to Table 1 below for the data of the experiment conducted according to the embodiment of the present disclosure to obtain a clearer understanding of the present disclosure. Among them, the metal plate 130 in the printing screen 100 adopts a double-layer electroformed plate structure, and the width of the graphic opening 140 is set to 11μm. Control group 1 in Table 1 is the test data of the scraper surface of the metal plate without roughening, and experimental groups A to D are the test data of the scraper surface of the metal plate with different degrees of roughening. The test process adopts a 1.5mm plate spacing and a scraper movement speed of 480mm / s for printing.

[0031]

[0032] (Table 1)

[0033] As shown in Table 1, the average roughness of experimental groups A-D ranged from 20nm to 5μm. Compared to the unroughened control group 1, the average line height and average width of the printed graphics were increased, and the aspect ratio was improved, indicating better ink permeability. However, further testing of print run quality showed that when the average roughness of the scraper surface exceeded 5μm, the print run number fell below 15,000. In other words, while a higher average roughness can improve ink permeability during printing, an excessively high average roughness can significantly reduce the print run number and make the mesh more susceptible to breakage.

[0034] Although the embodiments of the present disclosure have been disclosed above, they are not intended to limit the present disclosure. Those skilled in the art may make slight changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure shall be defined by the appended claims.

Claims

1. A printing screen, comprising: a frame; and A mesh is disposed in the mesh frame, wherein the mesh comprises: A metal plate, wherein the metal plate has a scraper surface and a printing surface, and the surface of the scraper surface is roughened to have an average roughness between 20nm and 5μm.

2. The printing screen as claimed in claim 1, wherein a material of the metal plate is selected from the group consisting of stainless steel, nickel alloy, titanium alloy, copper alloy, cobalt alloy, magnesium alloy and aluminum alloy. 3 . The printing screen as claimed in claim 1 , wherein the roughening treatment is one of sandblasting, grinding, chemical etching, laser treatment or a combination of two or more of the above. The printing screen as claimed in claim 1 , wherein the scraper surface comprises a plurality of concave recesses. The printing screen as claimed in claim 1 , wherein the scraper surface has unidirectional scratches.

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