A composite screen

Abstract

The application discloses a composite screen plate, comprising a glass substrate having a central pattern area and an edge area surrounding the central pattern area, the central pattern area being provided with a plurality of pattern holes penetrating through the thickness of the glass substrate; and a screen gauze being flatly covered on the first surface of the glass substrate by an adhesive and being bonded to the edge area, and the screen gauze on the central pattern area being cut off to expose the pattern holes.

Description

Technical Field

[0001] This invention relates to the field of printing screen technology, and in particular to a composite screen. Background Technology

[0002] In the field of printing stencil manufacturing technology, especially in high-precision electronic packaging printing and ball-mounting applications, two main types are currently used: screen printing stencils and stensil printing stencils. Screen printing stencils are typically made of mesh, with a thickness generally less than 100 micrometers, enabling the printing of graphics with a thickness ranging from 5 to 30 micrometers, and achieving a maximum graphic precision of 10 micrometers. However, because the stencil is prone to deformation under tension during printing, the positional and dimensional accuracy of the graphics is relatively weak, making precise positioning difficult. Furthermore, the mesh structure of screen printing stencils obstructs the view, limiting their application to fluid paste printing and making them unsuitable for solid material placement operations such as ball-mounting.

[0003] Steel stencils, with a thickness of over 100 micrometers, typically offer a printing precision better than 50 micrometers. Due to their high material rigidity and strong deformation control, they enable precise printing of graphics at designated locations. Furthermore, the absence of mesh obstruction makes them suitable for ball-planting processes.

[0004] Current stencil pattern fabrication primarily utilizes chemical etching, laser drilling, or electroforming. For high-precision patterns below 100 micrometers, electroforming is often necessary, but this method is prohibitively expensive, with a single stencil costing tens of thousands of yuan, limiting its widespread application. Furthermore, while electroformed stencils approach the micrometer-level limits in terms of pattern precision, aspect ratio, and sidewall smoothness, their high coefficient of thermal expansion (approximately 10 ppm) means that a 1-degree Celsius temperature change during fabrication and use results in a positional tolerance of approximately 1 micrometer per 100 millimeters. While this characteristic is acceptable for conventional surface mount technology (SMT) processes, the insufficient thermal stability of existing stencils becomes increasingly apparent as electronic packaging moves towards larger sizes and higher densities, particularly in precision applications like System-in-Package (SiP), making it difficult to meet the demands for higher-precision positioning. Summary of the Invention

[0005] In view of the above problems, this application provides a composite screen printing plate, which aims to solve the problems that screen printing plates are prone to deformation due to tension, resulting in weak control of graphic position and size accuracy, and are not suitable for placing solid materials such as ball-laying plates. In addition, steel sheet screen printing plates rely on costly electroforming processes when producing high-precision graphics below 100 micrometers, and the high coefficient of thermal expansion of the material results in insufficient thermal stability, making it difficult to meet the stringent positioning accuracy requirements of large-size and high-precision application scenarios such as system-in-package.

[0006] The present invention provides a composite screen printing plate, comprising: a glass substrate having a central graphic region and an edge region surrounding the central graphic region, the central graphic region having a plurality of graphic holes penetrating the thickness of the glass substrate; and a mesh fabric, the mesh fabric being flatly covered on a first surface of the glass substrate and adhered to the edge region by an adhesive, and the mesh fabric on the central graphic region being cut off to expose the graphic holes.

[0007] Optionally, the thickness of the glass substrate is less than 1 mm.

[0008] Optionally, the patterned hole has an opening size on the first surface of the glass substrate that is larger than the opening size on the second surface, and the sidewalls of the patterned hole are inclined.

[0009] Optionally, the edge region is provided with a plurality of through holes, and the adhesive is filled in the through holes.

[0010] Optionally, the edge region has a rough first surface.

[0011] Optionally, the roughness of the first surface of the edge region is 0.1 μm to 0.8 μm.

[0012] Optionally, the first and second surfaces of the glass substrate are coated with a protective adhesive layer.

[0013] Optionally, the protective adhesive layer covers the first and second surfaces of the glass substrate and exposes the port and sidewalls of the patterned hole.

[0014] Optionally, the edge of the protective adhesive layer contacts the edge of the adhesive, together covering the first surface of the glass substrate.

[0015] Optionally, the protective adhesive layer extends to the edge region and covers at least a portion of the surfaces of the adhesive and the mesh.

[0016] Optionally, the thickness of the protective adhesive 60 is 1μm to 50μm.

[0017] Optionally, the inner edge of the mesh is connected to the edge region of the glass substrate by the adhesive, and the outer edge of the mesh is connected to the metal mesh frame by the adhesive.

[0018] This application uses a glass substrate as the intermediate pattern mesh. The corrosion resistance and fatigue resistance of the glass substrate are far superior to those of steel wire or steel sheet. Compared with steel wire or steel sheet, the service life of the glass substrate is longer.

[0019] Furthermore, the transparency of the glass substrate allows for effective observation of the markings on the substrate and the entry points of the paste or ball-planting material beneath the glass substrate during the printing process, enabling automated alignment and AOI (Automated Optical Inspection).

[0020] Furthermore, etching processes can be used to form patterned holes on glass substrates, which is far less expensive than electroforming. The sidewall roughness of these etched holes is below 0.03 μm, significantly lower than that of electroforming, facilitating paste release. The glass substrate itself possesses excellent toughness, and the etching process does not create cracks or defects, further enhancing its toughness.

[0021] Furthermore, the coefficient of thermal expansion of the glass substrate is below 3.5ppm, which is lower than that of the stencil, making it suitable for large-size, high-precision packaging printing and ball placement.

[0022] In some embodiments, the inner edge of the mesh is connected to the edge region of the glass substrate by an adhesive, and the edge region of the glass substrate provides mechanical support for the inner edge of the mesh. The outer edge of the mesh is connected to the metal mesh frame by an adhesive, and the metal mesh frame provides mechanical support for the outer edge of the mesh, so that the mesh remains flat under the tension of the edge region of the glass substrate and the metal mesh frame, avoiding deformation during the printing process.

[0023] In some embodiments, the edge region of the glass substrate is provided with through holes penetrating the glass substrate, or the surface of the edge region is roughened, and the adhesive fills the through holes or covers the roughened surface to form a mechanical interlocking structure with the glass substrate. This mating relationship ensures that the composite screen structure formed by the mesh and the glass substrate has high strength and stability. The adhesive not only plays a bonding role, but also buffers external stress through its elastic properties.

[0024] In some embodiments, a protective adhesive layer is provided on the first and second surfaces of the glass substrate. The protective adhesive layer protects the glass substrate from abrasion caused by printing paste or ball bearings. Furthermore, the protective adhesive layer has a certain degree of elasticity, which disperses the local stress applied to the glass substrate through the elastic buffering effect of the protective adhesive layer, thereby reducing the risk of glass substrate breakage. Attached Figure Description

[0025] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0026] Figure 1 A top view schematic diagram of a screen printing plate provided according to the first embodiment of this application is shown;

[0027] Figure 2 A cross-sectional schematic diagram of a screen printing plate provided according to a first embodiment of this application is shown;

[0028] Figure 3 A cross-sectional schematic diagram of a screen printing plate provided according to a second embodiment of this application is shown. Detailed Implementation

[0029] The invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown.

[0030] This invention can be presented in various forms, some of which will be described below.

[0031] Figure 1 A top view schematic diagram of a screen printing plate provided according to the first embodiment of this application is shown. Figure 2 A cross-sectional schematic diagram of a screen printing plate according to a first embodiment of this application is shown. For example... Figure 1 and Figure 2 As shown, the screen printing structure includes a glass substrate 10 and a mesh 40.

[0032] The glass substrate 10 is made of TGV (Through Glass Via) glass and has a central graphic region 11 and an edge region 12 surrounding the central graphic region 11. The central graphic region 11 has multiple graphic holes 20 penetrating the thickness of the glass substrate 10. A mesh 40 is smoothly applied to the first surface of the glass substrate 10 using a screen-stretching process and is firmly bonded to the glass substrate 10 by an adhesive 50 applied to the edge region 12. Subsequently, the mesh 40 on the central graphic region 11 is cut away, fully exposing the graphic holes 20. The mesh 40 and the glass substrate 10 form a composite screen printing structure. This composite structure increases the tension of the screen during printing, facilitating print release.

[0033] In one embodiment, the thickness of the glass substrate 10 is less than 1 mm. An excessively thick glass substrate 10 lacks toughness and is prone to cracking. The top view shape of the patterned hole 20 can be circular, linear, polygonal, or irregular, etc., and this embodiment does not impose any limitations on this. The patterned hole 20 can be a straight hole, an oblique hole, or a trapezoid with a larger top and smaller bottom in cross-section. In one embodiment, the opening of the patterned hole 20 on the first surface of the glass substrate 10 has a first size, and the opening of the patterned hole 20 on the second surface of the glass substrate 10 has a second size. The first size is larger than the second size, and the sidewalls of the patterned hole 20 are inclined to form a trapezoidal patterned hole 20. This trapezoidal patterned hole 20 facilitates the filling and release of printing paste and also facilitates the insertion of ball implantation. In one embodiment, the difference between the first size and the second size of the patterned hole 20 is 2 μm to 20 μm.

[0034] This application uses a glass substrate 10 as the intermediate pattern mesh. The corrosion resistance and fatigue resistance of the glass substrate 10 are far superior to those of steel wire or steel sheet. Compared with steel wire or steel sheet, the service life of the glass substrate 10 is longer.

[0035] Furthermore, the transparency of the glass substrate 10 allows for effective observation of the marking points and the entry holes of the paste or ball-planting material on the substrate below the glass substrate 10 during the printing process, enabling automated alignment and AOI (Automated Optical Inspection).

[0036] Furthermore, an etching process can be used to form patterned holes 20 on the glass substrate 10. The manufacturing cost is much lower than that of the electroforming method. Moreover, the sidewall roughness of the patterned holes 20 formed by the etching process on the glass substrate 10 is less than 0.03μm, which is much lower than that of the electroforming method, and is conducive to the release of slurry.

[0037] Furthermore, the glass substrate 10 itself has excellent toughness, and the etching process does not form crack defects on the glass substrate 10, which further improves the toughness of the glass substrate 10.

[0038] Furthermore, the coefficient of thermal expansion of the glass substrate 10 is below 3.5ppm, which is lower than that of the stencil, making it suitable for large-size, high-precision packaging printing and ball placement.

[0039] In this embodiment, the edge region 12 of the glass substrate 10 is provided with densely and uniformly distributed through holes 30. The diameter of the through holes 30 is less than 30 μm. In one embodiment, the diameter of the through holes 30 is, for example, 10 μm to 20 μm. The through holes 30 are used to fill the adhesive 50. Specifically, the adhesive 50 is coated on the surface of the edge region 12 and fills the through holes 30 of the edge region 12 to form a continuous adhesive layer. The mesh 40 is flatly covered on the glass substrate 10 by a mesh-stretching process and is in close contact with the adhesive 50, so that the fiber structure of the mesh 40 and the adhesive 50 interweave and solidify with each other, thereby fixing the mesh 40 to the edge region 12 of the glass substrate 10.

[0040] In this embodiment, through-holes 30 are provided to enhance the bonding strength between the glass substrate 10 and the adhesive 50, so that the adhesive can better fix the glass substrate 10 and the mesh 40 together. Specifically, the adhesive 50 fills the through-holes 30, forming a mechanical interlocking structure with the glass substrate 10. This fit ensures that the composite mesh structure formed by the mesh 40 and the glass substrate 10 has high strength and stability. The adhesive 50 not only plays a bonding role, but also buffers external stress through its elastic properties.

[0041] In this embodiment, the first and second surfaces of the glass substrate 10 have protective adhesive layers 60. Specifically, the protective adhesive layer 60 includes a first protective adhesive layer 61 and a second protective adhesive layer 62. The first protective adhesive layer 61 is coated on the first surface of the glass substrate 10, forming a continuous thin film on the first surface of the glass substrate 10. The second protective adhesive layer 62 is coated on the second surface of the glass substrate 10, forming a continuous thin film on the second surface of the glass substrate 10. The first and second protective adhesive layers 61 and 62 spatially isolate the glass substrate 10 from the external environment. It is worth noting that the first protective adhesive layer 61 and the second protective adhesive layer 62 are coated on the first and second surfaces of the glass substrate 10, respectively, exposing the port and sidewalls of the patterned hole 20.

[0042] The first protective adhesive layer 61 and the second protective adhesive layer 62 are used to prevent scratches between the glass substrate 10 and the printing substrate, and to protect the glass substrate 10 from wear by printing paste or ball bearings. In addition, the first protective adhesive layer 61 and the second protective adhesive layer 62 have a certain elasticity, and the elastic buffering effect of the first protective adhesive layer 61 and the second protective adhesive layer 62 disperses the local stress applied to the glass substrate 10, thereby reducing the risk of breakage of the glass substrate 10.

[0043] Protective adhesive 60 can be thermosetting, thermoplastic, or UV-cured acrylic, polyurethane, or silicone organic adhesives. The thickness of protective adhesive 60 is 1μm to 50μm. If it is too thick, it can easily cause heat deformation and affect precision; if it is too thin, it will not be dense enough.

[0044] Furthermore, a first protective adhesive layer 61 and a second protective adhesive layer 62 are respectively coated on the first and second surfaces of the glass substrate 10. In the edge region 12, the edge of the first protective layer 61 contacts the edge of the adhesive 50 to completely cover the upper surface of the glass substrate 10. In other embodiments, the first protective adhesive layer 61 extends to the edge region 12, covering the adhesive 50 and the mesh 40 to form a complete protective cover. The upper surface of the adhesive 50 is fully bonded to the lower surface of the mesh 40, while the upper surface of the mesh 40 may be partially covered by the first protective adhesive layer 61. This fit further ensures the stability of the bond between the mesh 40 and the glass substrate 10.

[0045] In this embodiment, the composite screen structure of mesh 40 and glass substrate 10 is fixed to the metal frame 70 by adhesive 50, so that the screen maintains uniform tension during the printing process.

[0046] The metal frame 70 is a highly rigid rectangular frame structure. Its internal opening area is used to accommodate and fix the screen printing composite structure formed by the glass substrate 10 and the mesh 40. The mesh 40 is firmly bonded to the glass substrate 10 by an adhesive 50 applied to the edge region 12 of the glass substrate 10, and the peripheral extension of the mesh 40 is directly adhered to the inner edge frame of the metal frame 70 by additional adhesive 50. The inner edge of the mesh 40 is connected to the edge region 12 of the glass substrate 10 by adhesive 50, providing mechanical support for the inner edge of the mesh 40. The outer edge of the mesh 40 is connected to the metal frame 70 by adhesive 50, providing mechanical support for the outer edge of the mesh 40. This ensures that the mesh 40 remains flat under the tension of the edge region 12 of the glass substrate 10 and the metal frame 70, preventing deformation during the printing process.

[0047] When the screen is used for printing or ball-planting processes, the screen is placed above the substrate, and the printing paste or ball-planting material is precisely transferred to the substrate through the patterned holes 20 of the glass substrate 10. Because the glass substrate 10 has a low coefficient of thermal expansion, its dimensional changes due to temperature variations are minimal, thus ensuring high-precision stability of the pattern position. The high-precision machining and smooth sidewalls of the patterned holes 20 facilitate smooth filling and complete release of the paste, reducing residue.

[0048] The inner edge of the mesh 40 is connected to the edge region 12 of the glass substrate 10 by adhesive 50. The edge region 12 of the glass substrate 10 provides mechanical support for the inner edge of the mesh 40. The outer edge of the mesh 40 is connected to the metal frame 70 by adhesive 50. The metal frame 70 provides mechanical support for the outer edge of the mesh 40, so that the mesh 40 remains flat under the tension of the edge region 12 of the glass substrate 10 and the metal frame 70, avoiding deformation during the printing process.

[0049] The flexibility of the protective adhesive layer 60 further alleviates external impact stress and extends the life of the screen printing plate. In addition, the transparency of the glass substrate 10 allows the operator to directly observe the alignment marks and paste status of the substrate through the screen printing plate, supporting automated alignment and optical inspection.

[0050] Figure 3 A cross-sectional schematic diagram of a screen printing plate according to a second embodiment of this application is shown, as follows: Figure 3 As shown, unlike the first embodiment, in this embodiment, the surface of the edge region 12 of the glass substrate is roughened, and the surface roughness of the edge region 12 is 0.1μm~0.8μm, so that the adhesive can better bond the glass and the mesh together.

[0051] As described above, these embodiments of the present invention do not exhaustively cover all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite screen printing plate, wherein, include: A glass substrate having a central graphic region and an edge region surrounding the central graphic region, wherein the central graphic region is provided with a plurality of graphic holes penetrating the thickness of the glass substrate; as well as A mesh is applied smoothly to the first surface of the glass substrate and bonded to the edge region by an adhesive, and the mesh on the central pattern region is cut off to expose the patterned holes.

2. The composite screen printing plate according to claim 1, characterized in that, The thickness of the glass substrate is less than 1 mm.

3. The composite screen printing plate according to claim 1, characterized in that, The patterned hole has an opening size on the first surface of the glass substrate that is larger than the opening size on the second surface, and the sidewalls of the patterned hole are inclined.

4. The composite screen printing plate according to claim 1, characterized in that, The edge region is provided with multiple through holes, and the adhesive is filled in the through holes.

5. The composite screen printing plate according to claim 1, characterized in that, The edge region has a rough first surface.

6. The composite screen printing plate according to claim 1, characterized in that, The roughness of the first surface of the edge region is 0.1 μm to 0.8 μm.

7. The composite screen printing plate according to claim 1, characterized in that, The first and second surfaces of the glass substrate are coated with a protective adhesive layer.

8. The composite screen printing plate according to claim 7, characterized in that, The protective adhesive layer covers the first and second surfaces of the glass substrate and exposes the port and sidewalls of the patterned hole.

9. The composite screen printing plate according to claim 7, characterized in that, The edge of the protective adhesive layer contacts the edge of the adhesive, together covering the first surface of the glass substrate.

10. The composite screen printing plate according to claim 7, characterized in that, The protective adhesive layer extends to the edge region and covers at least a portion of the surface of the adhesive and the mesh.

11. The composite screen printing plate according to claim 7, characterized in that, The thickness of the protective adhesive 60 is 1μm~50μm.

12. The composite screen printing plate according to claim 1, characterized in that, The inner edge of the mesh is connected to the edge region of the glass substrate by the adhesive, and the outer edge of the mesh is connected to the metal mesh frame by the adhesive.

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