Constant tension electroforming printing template

Abstract

The utility model discloses a constant tension electroforming printing template, including net frame and electroforming screen board, and the electroforming screen board is through the tension wire mesh and is pulled on the net frame, and the inner periphery of tension wire mesh is bonded with the electroforming screen board, and the outer periphery of tension wire mesh is bonded on the outer frame wall of net frame by bypassing the bottom side of net frame, the frame wall of relative two sides of net frame is equipped with the tension device, and the tension device includes the wire mesh roof that touches with tension wire mesh, and the wire mesh roof other side supports the first leaf spring, and the second leaf spring is supported on two adjacent first leaf spring, and the third leaf spring is supported on two adjacent second leaf spring, the net frame is provided with leaf spring groove, and the wire mesh roof, first leaf spring, second leaf spring and third leaf spring are all installed in leaf spring groove, the third leaf spring is installed in the groove bottom position of leaf spring groove through leaf spring pad, and the leaf spring pad is soft rubber pad, and the template not only can automatically adjust screen board tension, but also can guarantee the uniformity of tension of each place of screen board surface.

Description

Technical Field

[0001] This utility model relates to packaging printing templates in chip manufacturing processes, and more particularly to improvements in the tension structure of packaging templates. Background Technology

[0002] With the rapid development of semiconductor technology, chip thickness has decreased while size has increased. The reduction in substrate linewidth and thickness has led to increased complexity and integration of package structures. In the chip manufacturing process, the packaging stencil is a high-precision printing tool used in ball grid array (BGA) packaging technology. Its main function is to accurately apply solder paste and precisely position solder balls on the pads of the printed circuit board to avoid bridging or poor soldering that could reduce product yield.

[0003] The core of packaging lies in solder joint quality and packaging efficiency, which are highly dependent on the packaging stencil. This requires not only highly precise mesh placement but also accurate control of solder volume to prevent chip malfunction due to solder joint issues. Typically, solder ball spacing is extremely small, even at the micrometer level. Existing packaging stencils mainly consist of a stencil frame and a stencil stretched across the frame. This stencil has several mesh holes for positioning and implanting solder balls. During the packaging process, stencil tension fluctuations and changes are prone to occur, especially uneven tension across the stencil, which can lead to changes in mesh hole placement and prevent precise solder ball implantation. Similarly, tension variations can cause uneven solder paste application, which in turn affects the solder ball placement effect. Furthermore, with repeated use of the packaging stencil, stencil tension also loosens, exacerbating problems such as uneven solder ball distribution and missing solder balls, directly impacting chip functionality and yield. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide a constant tension electroforming printing template that can not only automatically adjust the tension of the screen, but also ensure the uniformity of tension at all parts of the screen surface.

[0005] To solve the above-mentioned technical problems, the constant tension electroforming printing template of this utility model includes a frame, a tensioned wire mesh, and an electroforming screen plate. The electroforming screen plate is tensioned onto the frame by the tensioned wire mesh. The inner circumference of the tensioned wire mesh is bonded to the electroforming screen plate, and the outer circumference of the tensioned wire mesh is bonded to the outer frame wall of the frame, bypassing the bottom side of the frame. Tensioning devices are installed on the frame walls on opposite sides of the frame. The tensioning device includes a wire mesh top plate that contacts the tensioned wire mesh. A first leaf spring is supported on the other side of the wire mesh top plate. A second leaf spring is supported on two adjacent first leaf springs, and a third leaf spring is supported on two adjacent second leaf springs.

[0006] With the above structure, tension devices are installed on the two opposite frame walls of the screen frame, and these tension devices contact the tensioned wire mesh through the top plate of the screen. The tension devices provide a stable tension force to the tensioned wire mesh through the contact action, thereby ensuring the constant tension of the screen plate surface. Even if plastic deformation occurs during long-term repeated use of the printing template, the tension device can automatically compensate for the loosening of the screen surface caused by this deformation, and has an excellent stabilizing effect on the screen plate tension, achieving the technical effect of constant tension. Furthermore, since the tensioning device includes a first leaf spring, a second leaf spring, and a third leaf spring, with adjacent first leaf springs supported by corresponding second leaf springs, and adjacent second leaf springs supported by the third leaf spring, when the tension and compression forces on adjacent first leaf springs are inconsistent, the second leaf spring can automatically adjust the compression forces of the two adjacent first leaf springs. Similarly, when the forces on adjacent second leaf springs are inconsistent, the third leaf spring can automatically adjust the compression forces. Through the above-mentioned automatic adjustment, the tension force of the tensioned wire mesh and the mesh plate is ensured to be uniform and stable. The stable and consistent tension of the mesh plate ensures the accurate positioning of the mesh holes, as well as the uniform application of solder paste and accurate ball placement. Moreover, since the encapsulation template steel mesh uses an electroformed metal substrate, its high mechanical strength greatly increases the frequency of physical contact with the lithography machine and can significantly improve the positional and dimensional accuracy of the mesh holes.

[0007] Furthermore, the electroformed stencil is provided with electroformed mesh openings. The electroformed stencil is covered with a film layer, and the mesh openings on the film layer correspond to the positions of the electroformed mesh openings on the electroformed stencil. It possesses advantages such as high mechanical strength and corrosion resistance. The polymer film layer covering the electroformed stencil not only protects the stencil but also allows for the precise implantation of solder balls of different diameters.

[0008] Furthermore, the wire mesh frame is provided with spring grooves, and the wire mesh top plate, the first spring, the second spring, and the third spring are all installed in the spring grooves. The third spring is installed at the bottom of the spring groove via a spring pad, which is a soft rubber pad. The lengths of the first, second, and third springs are greater than the lengths of the corresponding sides of the electroformed wire mesh, ensuring the wire mesh surface remains consistently balanced.

[0009] Furthermore, the tensioning device includes four first leaf springs, two second leaf springs, and one third leaf spring. The first, second, and third leaf springs are arc-shaped elastic sheets with a thickness of 1 mm to 2 mm. This provides good automatic tension adjustment, ensuring stable tension. Attached Figure Description

[0010] The constant tension electroforming printing template of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0011] Figure 1 This is a cross-sectional structural schematic diagram of a specific embodiment of the constant tension electroforming printing template of this utility model; Figure 2 yes Figure 1 Top view; Figure 3 yes Figure 1 Enlarged structural diagram of section I; Figure 4 yes Figure 3 A schematic diagram of the A-A cross-sectional structure; Figure 5 yes Figure 1 Enlarged structural diagram of section II; Figure 6 yes Figure 4 Assembly drawing of the third leaf spring and leaf spring washer; Figure 7 yes Figure 6 The left view.

[0012] In the figure, 1—mesh frame, 2—tensioned wire mesh, 3—electroplated mesh plate, 4—film layer, 5—electroplated mesh holes, 6—film layer mesh holes, 7—tension device, 71—wire mesh top plate, 72—first leaf spring, 73—second leaf spring, 74—third leaf spring, 75—leaf spring pad, 8—die hole, 9—leaf spring groove. Detailed Implementation

[0013] like Figure 1 , Figure 2 The constant tension electroforming printing template shown includes a frame 1, a tensioned wire mesh 2, and an electroformed screen 3. The electroformed screen 3 is tensioned onto the frame 1 by the tensioned wire mesh 2. The frame 1 is a rectangular frame made of aluminum alloy. The tensioned wire mesh 2 is a U-shaped polyester wire mesh, and the electroformed screen 3 is bonded to the hollow area of ​​the tensioned wire mesh 2. The electroformed screen 3 is an electroformed nickel mesh made using an electroforming process. Several electroformed mesh holes 5 and electroformed die holes 8 are provided on the surface of the electroformed screen 3.

[0014] Tensioning devices 7 are installed in the leaf spring grooves 9 of the outer frame walls of the two opposing frame beams of the mesh frame 1. The inner periphery of the U-shaped tensioned wire mesh 2 is bonded to the outer periphery of the electroformed mesh plate 3 by adhesive. The outer periphery of the tensioned wire mesh 2 passes around the bottom side of the mesh frame 1 and is bonded to the upper end of the outer frame wall of the mesh frame 1 by the tensioning devices 7.

[0015] A film layer 4 is provided on the surface of the electroforming stencil plate 3, and the position of the film layer mesh 6 on the film layer 4 corresponds to the position of the electroforming mesh 5 on the electroforming stencil plate 3.

[0016] like Figure 3 , Figure 4As shown, a wire mesh top plate 71 is movably provided at the slot opening of the spring groove 9, and the outer surface of the wire mesh top plate 71 abuts against the inner surface of the tensioned wire mesh 2. Four first springs 72 are installed on the inner surface of the wire mesh top plate 71. A second spring 73 is correspondingly supported by two adjacent first springs 72 at both ends of the spring groove 9. The two outer ends of the second spring 73 press on the corresponding two first springs 72, that is, one end of the second spring 73 presses on one first spring 72, and the other end of the second spring 73 presses on another first spring 72.

[0017] Two second leaf springs 73 correspond to a third leaf spring 74. One end of the third leaf spring 74 presses against one of the second leaf springs 73, and the other end of the third leaf spring 74 presses against the other second leaf spring 73. The third leaf spring 74 is installed at the bottom of the leaf spring groove 9 through a leaf spring pad 75. The leaf spring pad 75 not only helps to stabilize the installation position of the third leaf spring 75, but also facilitates the automatic adjustment of the tension of the mesh plate.

[0018] The first leaf spring 72, the second leaf spring 73, and the third leaf spring 74 are arc-shaped elastic sheets made of elastic materials such as bronze or chromium manganese molybdenum steel, with a thickness of 1.5 mm. The thickness of the elastic sheet should preferably be between 1 mm and 2 mm depending on the actual use; the leaf spring pad 25 is made of elastic materials such as soft rubber or silicone.

[0019] like Figure 5 As shown, the electroforming mesh 5 on the electroforming stencil plate 3 is a cylindrical hole, while the film mesh 6 on the film layer 4 is an inverted conical hole. The bottom diameter of the inverted conical hole is equal to the diameter of the electroforming mesh 5, and the center lines of the electroforming mesh 5 and the film mesh 6 are on the same straight line. Alternatively, the electroforming mesh 5 and the film mesh 6 can be cylindrical holes of equal diameter.

[0020] like Figure 6 , Figure 7 The length of the third leaf spring 74 shown is equal to or slightly greater than the length of the corresponding side of the electroformed mesh plate 3. Similarly, the lengths of the first leaf spring 72 and the second leaf spring 73 are also equal to or slightly greater than the lengths of the corresponding sides of the electroformed mesh plate 3. The third leaf spring 74 adopts an arc-shaped arched cross-section structure, with a strip-shaped leaf spring pad 75 located at the arch apex of the third leaf spring 74. Presser feet are provided on both sides of the third leaf spring 74 to form a stable support with the second leaf spring 73; the first leaf spring 72 and the second leaf spring 73 adopt the same structural form.

[0021] The preferred exemplary embodiments of the present invention have been described above by way of illustration only. However, those skilled in the art can make various modifications and improvements to the described embodiments without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A constant tension electroforming printing template, comprising a frame (1), a tensioned wire mesh (2), and an electroforming stencil (3), wherein the electroforming stencil (3) is tensioned onto the frame (1) by the tensioned wire mesh (2), characterized in that: The inner periphery of the tensioned wire mesh (2) is bonded to the electroformed wire mesh plate (3), and the outer periphery of the tensioned wire mesh (2) is bonded to the outer frame wall of the wire mesh frame (1) around the bottom side of the wire mesh frame (1); tension devices (7) are installed on the frame walls on opposite sides of the wire mesh frame (1); the tension device (7) includes a wire mesh top plate (71) that contacts the tensioned wire mesh (2), a first leaf spring (72) is supported on the other side of the wire mesh top plate (71), a second leaf spring (73) is supported on two adjacent first leaf springs (72), and a third leaf spring (74) is supported on two adjacent second leaf springs (73).

2. The constant tension electroforming printing template according to claim 1, characterized in that: Electroforming mesh (5) is provided on the electroforming mesh plate (3).

3. The constant tension electroforming printing template according to claim 1, characterized in that: The electroformed stencil (3) is covered with a film layer (4), and the film layer mesh (6) on the film layer (4) corresponds to the electroformed mesh (5) on the electroformed stencil (3).

4. The constant tension electroforming printing template according to claim 1, 2 or 3, characterized in that: The wire mesh frame (1) is provided with a spring groove (9), and the wire mesh top plate (71), the first spring (72), the second spring (73) and the third spring (74) are all installed in the spring groove (9).

5. The constant tension electroforming printing template according to claim 4, characterized in that: The third leaf spring (74) is installed at the bottom of the leaf spring groove (9) via a leaf spring pad (75), which is a soft rubber pad.

6. The constant tension electroforming printing template according to claim 1, characterized in that: The lengths of the first leaf spring (72), the second leaf spring (73), and the third leaf spring (74) are greater than the lengths of the corresponding sides of the electroformed mesh plate (3).

7. The constant tension electroforming printing template according to claim 1, characterized in that: The tension device (7) includes four first leaf springs (72), two second leaf springs (73), and one third leaf spring (74).

8. The constant tension electroforming printing template according to claim 1, characterized in that: The first leaf spring (72), the second leaf spring (73) and the third leaf spring (74) are arc-shaped elastic sheets with a thickness of 1mm-2mm.

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