A stepped buffer type nickel-plated screen printing screen structure

Abstract

The utility model relates to a kind of stepped buffer formula nickel-plated wire screen printing steel mesh structure, including steel mesh base plate, its front is equipped with stepped buffer groove and opposite two side walls are in ladder structure, back is equipped with the electrocasting through-hole passing through stepped groove bottom, the electrocasting through-hole inner wall covers nickel layer;The structure is blocked by ladder side wall and unsatisfied silver paste, and simultaneously nickel-plated hole wall improves paste rolling property and filling uniformity, effectively solve the problem that the chip patching inclination rate is high, the connection layer cavity rate is too large and the thermal resistance increases caused by traditional steel mesh silver paste loss, thickness inclination.

Description

Technical Field

[0001] This utility model belongs to the field of power module packaging technology, specifically relating to a stepped buffer type nickel-plated wire mesh printed steel mesh structure. Background Technology

[0002] In the field of power module packaging, traditional screen printing using through-hole stencils for silver paste / solder paste application has significant drawbacks: due to the high smoothness and vertical structure of the through-hole walls of the stencil, the silver paste is prone to spikes (tailing), local missing parts, and thickness tilting during the printing process, resulting in high chip placement tilt rate, a surge in the risk of wire bonding breakage, and excessively high void ratio in the bonding layer after sintering. To address these technical problems, how to simultaneously achieve precise control of paste flow and highly uniform filling of micropores has become a critical technical bottleneck that urgently needs to be overcome. Utility Model Content

[0003] This utility model aims to provide a stepped buffer type nickel-plated wire mesh printing steel mesh structure to solve the technical problems of missing silver paste, spikes, and uneven thickness when using through-hole steel mesh for silver paste or solder paste application in existing wire mesh printing.

[0004] To solve the above technical problems, the present invention adopts the following technical solution: a stepped buffer type nickel-plated wire mesh printing steel mesh structure, including a steel mesh substrate, a stepped buffer groove on the front side of the steel mesh substrate, the two opposite sidewalls of the stepped buffer groove are both stepped; an electroformed through hole penetrating the bottom of the stepped buffer groove is provided on the back side of the steel mesh substrate; a nickel layer is provided on the inner wall of the electroformed through hole, and the surface roughness Ra of the nickel layer is ≥0.8μm.

[0005] Furthermore, the two stepped sidewalls are symmetrically arranged, and the other two opposite sidewalls in the stepped buffer groove are both vertical planes.

[0006] Furthermore, the steel mesh substrate is made of 304 stainless steel.

[0007] Furthermore, the thickness of the stepped buffer groove is 30%-50% of the thickness of the steel mesh substrate.

[0008] Furthermore, the nickel layer has a thickness of 5-15 μm.

[0009] Furthermore, the diameter tolerance of the electroformed through hole is ±2μm.

[0010] Compared with the prior art, the beneficial effects of this utility model are as follows: This utility model forms a stepped structure on the opposite side walls of the stepped buffer groove on the front side of the stencil substrate by laser cutting. Combined with the nickel plating layer on the inner wall of the electroformed through hole, the stepped structure can effectively block the spiked silver paste and incomplete silver paste generated during printing, avoiding the loss of silver paste. At the same time, the nickel layer reduces the smoothness of the hole wall to improve the rolling performance of solder paste and the micro-hole filling effect. Ultimately, it achieves uniform coating of silver paste at the through hole and precise control of tilt, completely solving the problems of high chip mounting tilt rate, excessive void rate of the bonding layer and excessive thermal resistance caused by the spiked silver paste and thickness tilt of traditional stencils. Attached Figure Description

[0011] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is an isometric view of a stepped buffer type nickel-plated wire mesh printing steel mesh structure according to this utility model; Figure 2 This is a top view of a stepped buffer type nickel-plated wire mesh printing steel mesh structure according to this utility model; Figure 3 This is a cross-sectional view of a stepped buffer type nickel-plated wire mesh printing steel mesh structure according to this utility model.

[0012] The components represented by each number in the attached diagram are as follows: 1. Steel mesh substrate; 2. Stepped buffer groove; 3. Stepped structure; 4. Electroformed through hole; 5. Nickel layer. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] The present invention will be further described in detail below with reference to the embodiments.

[0015] Specific Embodiment 1 of the stepped buffer nickel-plated wire mesh printing steel mesh structure provided by this utility model: This embodiment provides a stepped buffer nickel-plated wire mesh printing steel mesh structure, mainly used for silver paste printing on AMB ceramic substrates, the structure is as follows: Figure 1-3As shown, the system specifically includes a stencil substrate 1, which is preferably made of 304 stainless steel to ensure good corrosion resistance and strength. A stepped buffer groove 2 is laser-cut on the front side of the stencil substrate 1. The thickness of the stepped buffer groove 2 is 30%-50% of the thickness of the stencil substrate 1. The two opposite sidewalls of the stepped buffer groove 2 are both stepped structures 3, and these two stepped sidewalls are symmetrically arranged. The other two opposite sidewalls of the stepped buffer groove 2 are vertical planes. Electroforming through-holes 4 penetrating the bottom of the stepped buffer groove 2 are formed on the back side of the stencil substrate 1 using an electroforming process, creating paste channels. The aperture tolerance of the electroforming through-holes 4 is ±2μm. This precise aperture tolerance ensures that the dimensions of each electroforming through-hole 4 are consistent, making the output of solder paste or silver paste through these holes more stable and controllable during screen printing, ultimately improving product performance and reliability.

[0016] A specific embodiment 2 of the stepped buffer type nickel-plated wire mesh printing stencil structure provided by this utility model differs from specific embodiment 1 in that, in order to further reduce the smoothness of the stencil substrate 1, a nickel layer 5 with a thickness of 5-15μm is generated on the inner wall of the electroformed through hole 4 by electroplating process. The surface roughness Ra of the nickel layer 5 is ≥0.8μm, which prevents the solder paste from sliding on the stencil surface and increases the rolling properties during solder paste printing.

[0017] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0018] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A stepped cushioned nickel plated screen printing screen structure, characterized by: The steel mesh substrate (1) has a stepped buffer groove (2) on its front side, and the two opposite sidewalls of the stepped buffer groove (2) are stepped (3); the back side of the steel mesh substrate (1) has an electroformed through hole (4) that penetrates the bottom of the stepped buffer groove (2); the inner wall of the electroformed through hole (4) is provided with a nickel layer (5), and the surface roughness Ra of the nickel layer (5) is ≥0.8μm.

2. The screen printing screen structure according to claim 1, wherein: The two side walls with a stepped structure (3) are symmetrically arranged, and the other two opposite side walls in the stepped buffer groove (2) are both vertical planes.

3. The structure of claim 1, wherein the nickel-plated screen printing steel mesh is characterized by: The steel mesh substrate (1) is made of 304 stainless steel.

4. The screen printing screen structure according to claim 1, wherein: The thickness of the stepped buffer groove (2) is 30%-50% of the thickness of the steel mesh substrate (1).

5. The stepped cushioned nickel-plated screen printing screen structure according to claim 1, characterized in that: The nickel layer (5) has a thickness of 5-15 μm.

6. The stepped cushioned nickel-plated screen printing screen structure according to claim 1, characterized in that: The diameter tolerance of the electroformed through hole (4) is ±2μm.

Images