Electroformed steel mesh for electronic components

Abstract

This utility model discloses an electroformed steel mesh for electronic components, including a mesh plate and die holes and mesh openings disposed on the mesh plate. The mesh plate includes an electroformed die and a face-side film layer and a bottom-side film layer covering both sides of the electroformed die. The mesh openings include guide holes, electroformed mesh openings, and bottom-side mesh openings that correspond to each other. The diameter of the guide holes is larger than the diameter of the electroformed mesh openings. Two opposing guide ribs are disposed on the wall of each guide hole. The diameters of the electroformed mesh openings and the bottom-side mesh openings are equal. The center lines of the guide holes, electroformed mesh openings, and bottom-side mesh openings are located on the same straight line. The guide surface of each guide rib is an inclined plane extending from the upper end of the guide hole to the upper end of the corresponding electroformed mesh opening. Two or four guide ribs are disposed on the wall of each guide hole, with two opposing guide ribs located on the same diameter. This electroformed steel mesh can not only adapt to the requirements of implanting solder balls of different diameters but also avoid ball leakage.

Description

Technical Field

[0001] This utility model relates to the field of electronic component printing and packaging technology, and in particular to an electroforming mesh structure for semiconductor wafer packaging printing templates. Background Technology

[0002] As semiconductor manufacturing upgrades towards higher density and miniaturization, ball grid array (BGA) packaging has become the mainstream packaging form for high-end chips due to its high pin density and good heat dissipation. However, packaging efficiency and solder joint quality are highly dependent on the performance of the printed stencil.

[0003] The quality of solder joints directly determines the stability of the connection between the chip and the circuit board. Solder joint quality, in turn, depends on the packaging stencil. Traditional packaging stencils suffer from low aperture precision and rough hole walls, leading to uneven control of solder amount and solder ball position, resulting in issues like cold solder joints and bridging, with a solder joint yield of less than 90%. Electroformed stencils, on the other hand, use an electroforming process to continuously deposit metal ions under an electric field to create a metal template with a high-precision three-dimensional structure. Its dimensional accuracy can reach the micron or even nanometer level. Electroformed stencils not only enable the manufacture of high-precision complex structures but also offer excellent consistency and repeatability.

[0004] In the repair and manufacturing of semiconductor components, ball repositioning refers to the solder ball reloading process in Ball Grid Array (BGA) packaging, used to repair or package chips. Its core is the precise placement of solder balls, with the printed circuit board (PCB) serving as a crucial tool for accurately positioning the solder balls onto the chip pads. However, due to production efficiency considerations, electroformed stencil substrates are often ultra-thin metal plates. While increasing the thickness of the PCB substrate is technically feasible, it significantly extends the manufacturing cycle and increases production costs. Because of the large multiple relationship between the ultra-thin PCB and the solder ball size, the mesh openings on the PCB cannot accurately embed and position the solder balls, directly affecting solder joint yield and chip packaging quality. PCB repositioning aims to embed one solder ball in each PCB mesh opening; however, when the mesh opening diameter equals the solder ball diameter, the solder ball embedding rate decreases, increasing the probability of solder balls bypassing or circumventing the mesh openings, leading to missing solder balls. Utility Model Content

[0005] In view of the above-mentioned shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide an electroformed steel mesh for electronic components, which can not only adapt to the requirements of implanting solder balls of different diameters, but also avoid the phenomenon of ball leakage.

[0006] To solve the above-mentioned technical problems, the present invention provides an electroformed steel mesh for electronic components, comprising a mesh plate, and die holes and mesh holes disposed on the mesh plate. The mesh plate includes an electroformed template and a face-side film layer and a bottom-side film layer covering both sides of the electroformed template. The mesh holes include guide holes, electroformed mesh holes, and bottom-side mesh holes that are positioned corresponding to each other. The diameter of the guide holes is larger than the diameter of the electroformed mesh holes. The walls of the guide holes are provided with pairs of opposing guide ribs.

[0007] With the above structure, the high mechanical strength of the electroformed metal substrate used in the encapsulation template significantly increases the frequency of physical contact with the lithography machine, and also significantly improves the positional and dimensional accuracy of the mesh. The electroformed template is coated with a surface film and a bottom film on both sides, which not only effectively reduces the thickness of the electroformed substrate and lowers the cost of the printed encapsulation template, but also allows for the insertion of solder balls of different diameters by adjusting and replacing the side films with different thicknesses, thus increasing the template's applicability. The film coating on both sides of the electroformed substrate also provides effective protection, extending its service life and enhancing its resistance to lithography etching and high-frequency wear. Because the guide holes have a larger diameter than the electroformed mesh holes, and two opposing guide ribs are provided on the hole walls, the solder balls can be accurately guided into the mesh holes of the lithography machine. Furthermore, the rib structure reduces the frictional resistance of the solder balls during insertion, preventing solder ball leakage.

[0008] Furthermore, the guide holes, electroformed mesh holes, and bottom side mesh holes are all circular, and the diameters of the electroformed mesh holes and bottom side mesh holes are equal. The center lines of the guide holes, electroformed mesh holes, and bottom side mesh holes are located on the same straight line. This not only accommodates the requirements for implanting solder balls of different diameters, but also ensures accurate solder ball implantation and reliable positioning.

[0009] Furthermore, the guiding surface of the guide rib is an inclined plane, extending from the upper end of the guide hole to the upper end of the corresponding electroforming mesh hole. Two or four guide ribs are provided on the wall of the guide hole, with two opposing guide ribs located on the same diameter. This accurately guides the insertion of the solder ball, preventing missed insertion.

[0010] Furthermore, the electroforming template is an electroformed nickel mesh, and the surface and bottom film layers are formed by bonding polymer films. This provides advantages such as high mechanical strength and corrosion resistance. Attached Figure Description

[0011] The electroformed steel mesh for electronic components of this utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0012] Figure 1 This is a schematic diagram of a specific embodiment of the electroformed steel mesh for electronic components according to this utility model;

[0013] Figure 2 This is a magnified schematic diagram of the mesh structure in type 1;

[0014] Figure 3 yes Figure 2 Cross-sectional structural diagram of section A-A;

[0015] Figure 4 yes Figure 2 Cross-sectional structural diagram of section B-B;

[0016] In the figure, 1—mesh plate, 11—face-side film layer, 12—electroplated template, 13—bottom-side film layer, 2—mesh hole, 21—guide hole, 22—electroplated mesh hole, 23—bottom-side mesh hole, 3—mold hole, 4—guide rib. Detailed Implementation

[0017] like Figure 1 The electroformed steel mesh for electronic components shown includes a mesh plate 1, on which a plurality of through-holes 3 and mesh openings 2 are provided. The through-holes 3 are used to insert electronic component patches, and the mesh openings 2 are used to insert solder balls, such as solder balls.

[0018] The stencil 1 includes an electroforming template 12 located in the middle layer, which is an electroformed nickel mesh produced by an electroforming process. A surface film layer 11 is adhesively applied to the face side of the electroforming template 12, and a bottom film layer 13 is similarly adhesively applied to the bottom side. Both the surface film layer 11 and the bottom film layer 13 are made of polyimide film (PI film) and bonded to both sides of the electroforming template 12. The PI film has excellent corrosion and wear resistance, and also possesses high mechanical strength.

[0019] Each mesh 2 on the screen plate 1 is formed by stacking guide holes 21, electroformed mesh 22 and bottom mesh 23 that are in corresponding positions. The guide holes 21 are located on the surface film layer 11, the electroformed mesh 22 are located on the electroformed template 12, and the bottom mesh 23 are located on the bottom film layer 13.

[0020] like Figure 2 , Figure 3 and Figure 4 As shown, the guide hole 21, electroformed mesh 22, and bottom mesh 23 constituting mesh 2 are all circular through holes. The diameters of the electroformed mesh 22 and the bottom mesh 23 are equal, while the diameter of the guide hole 21 is larger than that of the electroformed mesh 22 and the bottom mesh 23. Furthermore, the center lines of the guide hole 21, the electroformed mesh 22, and the bottom mesh 23 are all located on the same straight line.

[0021] Four guide ribs 4 are provided on the wall of the guide hole 21. The four guide ribs 4 correspond to each other in pairs, that is, two opposite guide ribs 4 are located on the same diameter. Alternatively, two guide ribs 4 can be provided on the wall of the guide hole 21 on the same diameter. The guiding surface of the guide rib 4 facing the center line of the hole is an inclined surface. This inclined surface extends obliquely downward from the upper end of the guide hole 21 to the upper end of the corresponding electroforming mesh 22. This guide rib 4 can guide the solder ball to roll accurately into the electroforming mesh 22, so that the solder ball is accurately implanted into the electroforming mesh 22.

[0022] 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. An electroformed steel mesh for electronic components, comprising a mesh plate (1), and a mold hole (3) and a mesh hole (2) provided on the mesh plate (1), characterized in that: The stencil (1) includes an electroforming template (12), and a face-side film layer (11) and a bottom-side film layer (13) covering both sides of the electroforming template (12); the mesh (2) includes guide holes (21), electroforming mesh (22) and bottom-side mesh (23) that are corresponding to each other, the diameter of the guide holes (21) is larger than the diameter of the electroforming mesh (22); and two pairs of opposing guide ribs (4) are provided on the hole wall of the guide holes (21).

2. The electroformed steel mesh for electronic components according to claim 1, characterized in that: The guide hole (21), electroformed mesh (22) and bottom mesh (23) are all circular holes, and the diameters of the electroformed mesh (22) and bottom mesh (23) are equal.

3. The electroformed steel mesh for electronic components according to claim 1 or 2, characterized in that: The center lines of the guide hole (21), the electroformed mesh (22), and the bottom mesh (23) are located on the same straight line.

4. The electroformed steel mesh for electronic components according to claim 1, characterized in that: The guiding surface of the guide rib (4) is an inclined surface that extends from the upper end of the guide hole (21) to the upper end of the corresponding electroforming mesh (22).

5. The electroformed steel mesh for electronic components according to claim 1, characterized in that: Two or four guide ribs (4) are provided on the wall of the guide hole (21), and two opposite guide ribs (4) are located on the same diameter.

6. The electroformed steel mesh for electronic components according to claim 1, characterized in that: The electroforming template (12) is an electroformed nickel mesh, and the surface film layer (11) and the bottom film layer (13) are made of polymer film.

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