A magnetic squeegee system for SMT printing

Abstract

The utility model relates to a kind of magnetic scraper system for SMT printing, including magnetic scraper assembly and 3D steel net;3D steel net includes screen plate and side wall, several screen holes for tin paste flow are distributed in the strip area of screen plate along the direction of squeegee, one side or both sides of strip area is equipped with two convex strips extending along the direction of squeegee;Magnetic scraper assembly includes scraper holder and the magnetic scraper blade of inclination installation in the lower part of scraper holder, the lower edge of magnetic scraper blade and the upper surface of screen plate attract each other, the lower edge of magnetic scraper blade is equipped with two grooves, and convex strip and groove structure are matched with position.This system limits the position of tin paste by convex strip, so that tin paste flows basically or completely only in strip area in squeegeeing, reduces waste;The structural rigidity of strip area part is improved, squeegee failure caused by uneven screen plate itself is avoided;Limit the moving direction of magnetic scraper assembly with groove, whether 3D steel net is placed correctly can be predicted in advance.

Description

Technical Field

[0001] This utility model relates to the field of clamping and positioning technology, and in particular to a magnetic squeegee system for SMT printing. Background Technology

[0002] In SMT (Surface Mount Technology) processes, solder paste printing is a critical step, and its quality directly affects the reliability of subsequent component placement and soldering. Traditional squeegees are usually made of metal or rubber, which has the following drawbacks:

[0003] 1. Traditional squeegees require significant pressure to evenly print solder paste onto the PCB board, resulting in high energy consumption of the equipment;

[0004] 2. Traditional squeegees have poor adaptability to stencils, especially on 3D stencils (stencils with complex three-dimensional structures), which can easily lead to uneven printing or missing prints.

[0005] 3. Rubber scrapers are prone to wear, and metal scrapers are prone to deformation, leading to frequent replacements and increasing production costs;

[0006] 4. The wiring process is time-consuming, and the equipment and debugging are inconvenient, which affects production efficiency.

[0007] Chinese patent CN207291263U discloses a magnetic squeegee device for an SMT printer, including a squeegee blade and a squeegee insert. The squeegee insert is made of a material that can be magnetically attracted. Clearly, the squeegee insert can magnetically attach to the stencil that controls the amount of solder applied, ensuring that the edge of the squeegee insert remains in close contact with the upper surface of the stencil. However, the stencil itself may warp due to deformation, and in this case, there is still a risk of uneven printing.

[0008] Therefore, it is necessary to improve the structure of the magnetic scraper system to solve the above problems. Utility Model Content

[0009] The main objective of this invention is to provide a magnetic squeegee system for SMT printing, which can enhance the structural rigidity of the stencil and guide the magnetic squeegee blade to ensure the quality of solder coating.

[0010] This utility model achieves the above-mentioned objective through the following technical solution: a magnetic squeegee system for SMT printing, comprising a magnetic squeegee assembly and a 3D stencil; the 3D stencil includes a stencil plate and sidewalls, wherein a plurality of mesh holes for solder paste to flow down are distributed in a strip-shaped area along the squeegee direction on the stencil plate, and two protrusions extending along the squeegee direction are provided on one or both sides of the strip-shaped area; the magnetic squeegee assembly includes a squeegee holder and a magnetic squeegee blade inclinedly installed at the lower part of the squeegee holder, wherein the lower edge of the magnetic squeegee blade attracts each other to the upper surface of the stencil plate, and the lower edge of the magnetic squeegee blade is provided with two grooves, wherein the protrusions and the grooves are structurally and positionally matched.

[0011] Specifically, the 3D steel mesh also includes side walls that surround the upper edge of the mesh panel to form a trough-shaped structure that is low in the middle and high around the edges.

[0012] Specifically, the two protrusions have different widths.

[0013] Specifically, the lower part of the convex strip is provided with multiple block-shaped grooves distributed in the scraping direction.

[0014] Specifically, the magnetic scraper assembly consists of two magnetic scraper blades with opposite inclination directions and the distance between their lower ends being greater than the distance between their upper ends.

[0015] Specifically, the magnetic scraper blade is inlaid with magnetic material.

[0016] Specifically, the magnetic scraper assembly also includes two solder guards, which are respectively disposed on both sides of the scraper holder. The lower part of the solder guard is elastic and its lowest point is not higher than the lowest point of the magnetic scraper blade.

[0017] The beneficial effects of this utility model's technical solution are:

[0018] 1. By restricting the position of the solder paste with raised strips, the solder paste flows mainly or entirely within the strip area during application, reducing waste;

[0019] 2. Improve the structural rigidity of the strip area to make the strip area more flat and avoid poor coating caused by unevenness of the screen itself;

[0020] 3. The groove restricts the movement direction of the magnetic scraper assembly, allowing for early prediction of whether the 3D steel mesh is placed correctly. Attached Figure Description

[0021] Figure 1 A perspective view of a magnetic squeegee system for SMT printing;

[0022] Figure 2 A three-dimensional view of one of its magnetic scraper components;

[0023] Figure 3 This is a partial cross-sectional view of the magnetic scraper blade and the stencil near the raised strip.

[0024] The numbers in the image represent:

[0025] 1-Magnetic scraper assembly, 11-Scraper holder, 12-Magnetic scraper blade, 121-Groove, 13-Solder protector;

[0026] 2-3D steel mesh, 21-mesh plate, 211-mesh hole, 212-convex strip, 213-block groove, 22-side wall. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments.

[0028] Example:

[0029] like Figure 1 As shown, the present invention provides a magnetic squeegee system for SMT printing, comprising a magnetic squeegee assembly 1 and a 3D stencil 2.

[0030] A 3D stencil 2 is placed on the surface of the electronic product to control the amount of solder paste flowing to the back. A magnetic squeegee assembly 1 is used to scrape the upper surface of the 3D stencil 2 horizontally, causing the solder paste to flow into the mesh openings 211 on the 3D stencil 2. The solder paste applied to the electronic product is placed inside the mesh openings 211.

[0031] like Figure 1 and Figure 3 As shown, the 3D stencil 2 includes a stencil plate 21 and sidewalls 22. The sidewalls 22 surround the upper edge of the stencil plate 21 to form a groove-shaped structure that is low in the middle and high around the edges. Several mesh holes 211 for solder paste to flow down are distributed in a strip-shaped area along the coating direction on the stencil plate 21. Two protrusions 212 extending along the coating direction are provided on one or both sides of the strip-shaped area. The two protrusions 212 have different widths. Multiple block-shaped grooves 213 distributed in the coating direction are provided at the lower part of the protrusions 212.

[0032] To clearly show the relative positions of mesh 211 and ridge 212, Figure 3The thickness of the stencil 21 is intentionally increased because the actual amount of solder applied at each location is very small. Therefore, the actual thickness of the stencil 21 is even smaller than the aperture of the mesh 211. Because of this, a simple flat structure like the stencil 21 is prone to twisting and deformation. A flowing solder paste is first dripped onto the upper part of the stencil 21, and the sidewalls 22 are used to prevent the solder paste from flowing out of the stencil 21 from the edges. The flowing solder paste is initially located at one end of the strip area, and the magnetic squeegee assembly 1 guides the solder paste to the other end along the squeegee direction. Each time the solder paste encounters a mesh 211, a portion flows into the mesh 211. The first function of the raised strip 212 is to restrict the position of the solder paste. During squeegee application, solder paste easily flows outside the area where the mesh 211 is located, leading to waste. However, two raised strips 212 ensure that the solder paste flows primarily (when there is a raised strip 212 on one side) or completely (when there are raised strips 212 on both sides) within the strip area during squeegee application, reducing waste. The second function of the raised strip 212 is to improve the structural rigidity of the strip area, making it more flat and avoiding poor squeegee application caused by unevenness of the stencil 21 itself. The third function of the raised strip 212 is to restrict the movement direction of the magnetic squeegee assembly 1 in conjunction with the groove 121, allowing for early prediction of whether the 3D stencil 2 is correctly placed. When there is a block groove 213 at the bottom of the raised strip 212, the raised strip 212 will display a bottomed mesh structure. Compared to a simple long strip structure, this not only reduces its own weight but also has better structural rigidity, and can better assist the stencil 21 in achieving better structural rigidity.

[0033] like Figure 1 and Figure 2 As shown, there are two magnetic squeegee assemblies 1. Each magnetic squeegee assembly 1 includes a squeegee holder 11, a magnetic squeegee blade 12 inclinedly mounted on the lower part of the squeegee holder 11, and two solder guards 13 respectively disposed on both sides of the squeegee holder 11. The lower edge of the magnetic squeegee blade 12 attracts the upper surface of the stencil 21. The two magnetic squeegee blades 12 are inclined in opposite directions, and the distance between their lower ends is greater than the distance between their upper ends. Each magnetic squeegee blade 12 has two grooves 121 on its lower edge. The protrusions 212 and the grooves 121 are structurally and positionally matched. Magnetic material is embedded inside the magnetic squeegee blade 12. The lower part of the solder guard 13 is elastic, and its lowest point is not higher than the lowest point of the magnetic squeegee blade 12.

[0034] Both the magnetic squeegee blade 12 and the stencil 21 are made of magnetically conductive material, allowing them to attract each other when brought close enough. The magnetism of the magnetic squeegee blade 12 can originate from magnetic materials or electromagnetism. When the squeegee holder 11 moves, the magnetic squeegee blade 12 and the stencil 21 maintain line contact with almost no gap (only the protrusion 212 and the groove 121 can have a gap), and the solder paste moves within the angle formed by the two blades. Because the magnetic squeegee blade 12 typically makes one round trip during solder paste application, and the solder paste must remain within the two blades, the two blades must have a downward-opening structure. The solder guard 13 limits the closest distance between the squeegee holder 11 and the upper surface of the stencil 21, preventing excessive deformation of the magnetic squeegee blade 12 and scratching the surface of the stencil 21.

[0035] The above descriptions are merely some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and all such modifications and improvements fall within the protection scope of this utility model.

Claims

1. A magnetic squeegee system for SMT printing, comprising a magnetic squeegee assembly and a 3D stencil; characterized in that: The 3D stencil has several mesh holes distributed in a strip-shaped area along the squeegee direction for solder paste to flow down. Two protrusions extending along the squeegee direction are provided on one or both sides of the strip-shaped area. The magnetic squeegee assembly includes a squeegee holder and a magnetic squeegee blade inclinedly installed at the lower part of the squeegee holder. The lower edge of the magnetic squeegee blade attracts each other to the upper surface of the 3D stencil. The lower edge of the magnetic squeegee blade is provided with two grooves. The structure and position of the protrusions and the grooves are matched.

2. The magnetic squeegee system for SMT printing according to claim 1, characterized in that: The 3D steel mesh also includes side walls that surround the upper edge of the 3D steel mesh to form a trough-shaped structure that is low in the middle and high around the edges.

3. The magnetic squeegee system for SMT printing according to claim 1, characterized in that: The two protrusions have different widths.

4. The magnetic squeegee system for SMT printing according to claim 1, characterized in that: The lower part of the convex strip has multiple block-shaped grooves distributed in the scraping direction.

5. The magnetic squeegee system for SMT printing according to claim 1, characterized in that: The magnetic scraper assembly consists of two magnetic scraper blades, with the two blades tilted in opposite directions and the distance between their lower ends being greater than the distance between their upper ends.

6. The magnetic squeegee system for SMT printing according to claim 1, characterized in that: The magnetic scraper blade is inlaid with magnetic material.

7. The magnetic squeegee system for SMT printing according to claim 1, characterized in that: The magnetic scraper assembly also includes two solder guards, which are respectively disposed on both sides of the scraper holder. The lower part of the solder guard is elastic and its lowest point is not higher than the lowest point of the magnetic scraper blade.

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