Stepped printing steel mesh

Abstract

The utility model discloses a stepped printing steel mesh which comprises a first steel plate and a second steel plate, a plurality of first open holes are formed in the first steel plate, the second steel plate is arranged on the first steel plate and located above the first steel plate in the vertical height direction, and a plurality of second open holes are formed in the second steel plate. And the first open holes and the second open holes are correspondingly arranged, so that a plurality of semi-stepped holes and a plurality of full-stepped holes are formed. According to the utility model, part of the holes of the printing steel mesh are designed to be the full-step holes, and part of the holes are designed to be the half-step holes, so that the distribution of solder paste printing thickness is optimized through the distribution of the full-step holes and the half-step holes, the local solder paste thickness is increased, the short circuit and pseudo soldering are reduced, and the welding yield and reliability can be effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to surface mount technology field especially relates to a stepped printing steel net. BACKGROUND

[0002] In SMT (Surface Mount Technology, surface mount technology) process, steel net is the key tool of controlling tin paste printing thickness and distribution. The traditional steel net adopts plane steel sheet design, realizes tin paste transfer through the hole in the steel sheet, and the printing thickness is mainly adjusted through the overall thickness of the steel sheet. However, this kind of uniform thickness design has some defects in practical application, such as, the conventional plane steel net controls the printing thickness through the thickness of the steel sheet, the printing thickness is consistent, and it is impossible to carry out differentiated thickness control for specific areas (such as the connector two ends and the middle pin), tin paste shortage or excess may easily occur during welding, and then short circuit and false welding defects may easily occur, thereby affecting the welding strength. SUMMARY

[0003] The technical problem to be solved by the utility model is to provide a stepped printing steel net to solve the problem that the existing stepped printing steel net cannot carry out differentiated thickness control.

[0004] In order to solve the above technical problem, the technical scheme adopted by the utility model is as follows: a stepped printing steel net, which comprises a first steel plate and a second steel plate, a plurality of first holes are arranged on the first steel plate, the second steel plate is arranged on the first steel plate and located above the vertical height direction of the first steel plate, and a plurality of second holes are arranged on the second steel plate; wherein, the first hole and the second hole are arranged correspondingly to form a plurality of half-step holes and a plurality of full-step holes.

[0005] Further, in the stepped printing steel net, the central part of the first steel plate is provided with a printing area, the first hole is located on the printing area, and the second steel plate is welded on the printing area.

[0006] Further, in the stepped printing steel net, the second steel plate comprises a connecting part and two steel sheet parts, the two ends of the connecting part are connected with the steel sheet parts respectively to form a I-shaped structure.

[0007] Further, in the stepped printing steel net, the second hole comprises a first U-shaped hole and a second U-shaped hole, the first U-shaped hole is located on the connecting part, and the second U-shaped hole is located on the steel sheet part.

[0008] Further, the first through hole and the first U-shaped hole are communicated correspondingly to form the half-step hole, and the second through hole and the second U-shaped hole are communicated correspondingly to form the full-step hole.

[0009] Further, the length of the first through hole along the first direction is greater than the length of the first U-shaped hole along the first direction, and the length of the second through hole along the first direction is equal to the length of the second U-shaped hole along the first direction.

[0010] Further, the length of the first through hole along the first direction is greater than the length of the first U-shaped hole along the first direction, and the length of the second through hole along the first direction is equal to the length of the second U-shaped hole along the first direction.

[0011] Further, the first through hole and the first U-shaped hole are communicated correspondingly to form the half-step hole, and the second through hole and the second U-shaped hole are communicated correspondingly to form the full-step hole.

[0012] Further, the plurality of full-step holes are divided into two first hole groups, each first hole group comprises at least one full-step hole, the plurality of half-step holes comprise a second hole group, and the two first hole groups are symmetrically arranged on two sides of the second hole group.

[0013] Further, the thickness d1 of the first steel plate is 0.1mm≤d1≤0.15mm, and the thickness d2 of the second steel plate is 0.3mm≤d2≤0.5mm.

[0014] The printing steel net provided by the utility model has the advantages that the printing steel net comprises full-step holes and half-step holes, the holes of the printing steel net are designed in a stepped mode, the advantages of the full-step printing steel net and the half-step printing steel net are combined, part of the holes of the printing steel net are designed as full-step holes, and part of the holes of the printing steel net are designed as half-step holes, so that the tin paste printing thickness distribution is optimized through the distribution of the full-step holes and the half-step holes, the local tin paste thickness is increased, short circuit and virtual welding are reduced, and the welding yield and reliability can be effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A structure schematic view of the stepped printing steel mesh under one implementation and one visual angle of the utility model.

[0016] Figure 2 Another structure schematic view of the stepped printing steel mesh under one implementation and one visual angle of the utility model.

[0017] Figure 3 A top view of the stepped printing steel mesh under one implementation of the utility model.

[0018] Figure 4 A-a cross section schematic view of the stepped printing steel mesh. Figure 3

[0019] B-b cross section schematic view of the stepped printing steel mesh. Figure 5 Figure 3 A top view of the first steel plate in the stepped printing steel mesh under one implementation of the utility model.

[0020] Figure 6 A top view of the second steel plate in the stepped printing steel mesh under one implementation of the utility model.

[0021] Figure 7 Label explanation:

[0022] 1, first steel plate; 11, first through hole; 12, second through hole; 13, third through hole;

[0023] 2, second steel plate; 21, connecting part; 22, steel sheet part; 23, first U-shaped hole; 24, second U-shaped hole; 25, third U-shaped hole;

[0024] 3, half stepped hole;

[0025] 4, full stepped hole;

[0026] 5, link hole.

[0027] Specific implementation For detailed description of the technical content, purposes and effects of the utility model, the following will be described in conjunction with the drawings.

[0028] For detailed description of the technical content, purposes and effects of the utility model, the following will be described in conjunction with the drawings.

[0029] Please refer to Figures 1 to 7 ​This utility model provides a stepped printing stencil, which includes a first steel plate 1 and a second steel plate 2. The first steel plate 1 is provided with a plurality of first openings. The second steel plate 2 is disposed on the first steel plate 1 and located above the first steel plate 1 in the vertical height direction. The second steel plate 2 is provided with a plurality of second openings. The first openings and the second openings are arranged correspondingly to form a plurality of full-step holes 4 and a plurality of half-step holes 3.

[0030] As can be seen from the above description, the beneficial effects of this utility model are as follows: This utility model provides a printed stencil including full-step holes 4 and half-step holes 3. By designing the openings of the printed stencil in a stepped manner, combining the advantages of full-step and half-step printed stencil openings, some openings of the printed stencil are designed as full-step holes 4, and some openings are designed as half-step holes 3. This optimizes the solder paste printing thickness distribution through the distribution of full-step holes 4 and half-step holes 3, increases the local solder paste thickness, reduces short circuits and cold solder joints, and effectively improves soldering yield and reliability. Furthermore, this utility model, by setting a second steel plate 2 on the first steel plate 1, thickens the opening positions of the connectors on the first steel plate 1 using the second steel plate 2, increasing the solder paste thickness at the connector openings, improving soldering reliability, and without affecting the soldering effect of surrounding components.

[0031] Furthermore, in the stepped printing stencil of this utility model, the first steel plate 1 has a printing area in the center, the first opening is located on the printing area, and the second steel plate 2 is welded on the printing area.

[0032] The printed area is the corresponding opening area of ​​the connector. In practical applications, the second steel plate 2 can be laser welded onto the printed area of ​​the first steel plate 1.

[0033] Furthermore, in the stepped printing stencil of this utility model, the second steel plate 2 includes a connecting part 21 and two steel sheet parts 22. The two ends of the connecting part 21 are respectively connected to the steel sheet parts 22 to form an I-shaped structure.

[0034] In practical applications, the steel sheet portion 22 extends along a first direction, the connecting portion 21 extends along a second direction, and each end of the connecting portion 21 is connected to a steel sheet portion 22, thereby forming a second steel plate 2 with an I-shaped structure.

[0035] Furthermore, in the stepped printing stencil of this utility model, the second opening includes a first U-shaped hole 23 and a second U-shaped hole 24. The first U-shaped hole 23 is located on the connecting portion 21, and the second U-shaped hole 24 is located on the steel sheet portion 22. It should be noted that the first direction is the horizontal width direction of the stepped printing stencil (i.e.,...). Figure 3The second direction is the horizontal length direction of the stepped printing screen, and the second direction is perpendicular to the first direction. Figure 3 The diagonal filling part in the second steel plate is a second steel plate.

[0036] According to the above description, different second openings are arranged at different positions of the second steel plate 2, so that different stepped holes (such as full stepped holes 4 and half stepped holes 3) can be formed by the different second openings.

[0037] Further, in the stepped printing screen, the first opening includes a first through hole 11 and a second through hole 12, the first through hole 11 is in communication with the first U-shaped hole 23 to form the half stepped hole 3, and the second through hole 12 is in communication with the second U-shaped hole 24 to form the full stepped hole 4.

[0038] Further, in the stepped printing screen, the length of the first through hole 11 along the first direction is greater than the length of the first U-shaped hole 23 along the first direction, and the length of the second through hole 12 along the first direction is equal to the length of the second U-shaped hole 24 along the first direction.

[0039] In actual application, as shown in Figure 2 and Figure 3 Because the length of the first through hole 11 along the first direction is greater than the length of the first U-shaped hole 23, a corresponding half stepped hole 3 is formed. In the half stepped hole 3, the hole depth (that is, the thickness along the vertical height direction) is not consistent, and according to the hole depth of the half stepped hole 3, the half stepped hole 3 can be roughly divided into two parts, the hole depth of the first part near the connecting part 21 is greater than the hole depth of the second part away from the connecting part 21. The hole depth of the half stepped hole at the position near the connecting part 21 = the thickness of the first steel plate 1 + the thickness of the second steel plate 2, and the hole depth at the position away from the connecting part 21 = the thickness of the first steel plate 1. Because the length of the second through hole 12 along the first direction is equal to the length of the second U-shaped hole 24 along the first direction, a full stepped hole 4 is formed accordingly. The hole depth of the full stepped hole 4 is consistent, and the hole depth of the full stepped hole 4 = the thickness of the first steel plate 1 + the thickness of the second steel plate 2.

[0040] Further, in the stepped printing screen, the length of the first through hole 11 along the first direction is equal to the length of the second through hole 12 along the first direction, and the length of the first U-shaped hole 23 along the first direction is less than the length of the second U-shaped hole 24 along the first direction.

[0041] As described above, based on the fact that the length of the first through hole 11 along the first direction is equal to the length of the second through hole 12 along the first direction, by adjusting the lengths of the first U-shaped hole 23 and the second U-shaped hole 24 along the first direction, the corresponding full-step hole 4 and half-step hole 3 can be easily and quickly formed, improving the usability. That is, different second openings are opened at different positions on the second steel plate 2, so as to facilitate the formation of different stepped holes (such as full-step hole 4 and half-step hole 3) on the first steel sheet through different second openings.

[0042] Furthermore, in the stepped printed steel mesh of this utility model, the first opening further includes a third through hole 13, and the second opening further includes a third U-shaped hole 25. The third U-shaped hole 25 is correspondingly connected to the third through hole 13 to form a connecting hole 5. In the second direction, the third U-shaped hole 25 is located between the first U-shaped hole 23 and the second U-shaped hole 24.

[0043] In practical applications, such as Figure 4 As shown, one side of the connecting hole 5 is a steel sheet portion 22, and the other side is a connecting portion 21. As can be seen from the above, the connecting hole 5 consists of two parts: a third through hole 13 and a third U-shaped hole 25. The two sides of the third through hole 13 have equal lengths along the first direction; the two sides of the third U-shaped hole 25 have unequal lengths along the first direction. The length of its first side along the first direction is equal to the length of the first U-shaped hole 23 along the first direction, and the length of its second side along the first direction is equal to the length of the second U-shaped hole 24 along the first direction.

[0044] It should be noted that, in the second direction, the openings on the first steel plate located between the two third through holes are all first through holes, and the openings on the second steel plate located between the two third U-shaped holes are all first U-shaped holes.

[0045] Furthermore, in the stepped printing stencil of this utility model, the plurality of full-step holes 4 are divided into two first hole groups, each first hole group including at least one full-step hole 4, and the plurality of half-step holes 3 include a second hole group, with the two first hole groups symmetrically arranged on both sides of the second hole group.

[0046] In practical applications, the openings corresponding to the first 2-3 sets of pins at both ends of the connector can be set as full-step holes 4, thus forming two sets of full-step holes 4. The openings corresponding to the remaining pins in the middle of the connector can be designed as half-step holes 3, thus forming one set of half-step holes 3. The advantages of doing this are: by setting full-step holes 4 at both ends of the printing area of ​​the stencil and setting half-step holes 3 in the middle of the printing area, differentiated thickness control can be achieved for the pins at both ends and the middle of the connector, reducing the occurrence of insufficient or excessive solder paste, reducing defects such as short circuits and cold solder joints, and improving the soldering strength of the connector.

[0047] Furthermore, in the stepped printing stencil of this utility model, the thickness d1 of the first steel plate 1 is: 0.1mm≤d1≤0.15mm, and the thickness d2 of the second steel plate 2 is: 0.3mm≤d2≤0.5mm.

[0048] In practical applications, the first steel plate 1 can be made of steel sheet with a thickness of 0.1mm, 0.12mm or 0.15mm, and the second steel plate 2 can be made of steel sheet with a thickness of 0.5mm, without any limitation.

[0049] Correspondingly, this utility model also provides a method for preparing a stepped printed stencil, specifically: (1) Select a first steel plate 1 with a thickness of 0.1mm, 0.12mm, or 0.15mm. (2) According to the PCB pad design gerber, perform hole-making operations on the first steel plate 1, and perform 10% to 20% extension design for the hole corresponding to the connector pad. (3) Use laser welding to weld an inverted I-shaped steel plate (i.e., the second steel plate 2) with a thickness of 0.3mm to 0.5mm at the location of the hole corresponding to the connector on the first steel plate 1. (4) According to the PCB pad design gerber, perform hole-making operations again in the area of ​​the printed stencil corresponding to the connector pad, and perform 10% to 20% extension design.

[0050] Please refer to Figures 1 to 7 The first embodiment of this utility model is: a stepped printed steel mesh, which includes a first steel plate 1 and a second steel plate 2. The length and width of the second steel plate 2 are respectively smaller than the length and width of the first steel plate 1, and the second steel plate 2 is laser welded onto the first steel plate 1.

[0051] In this embodiment, as Figure 6 As shown, the printing area of ​​the first steel plate 1 has two rows of first openings, which are symmetrically arranged and spaced apart. Each row of first openings includes, along the first direction, a second through hole 12, a third through hole 13, multiple first through holes 11, a third through hole 13, and a second through hole 12. The first openings are all rectangular and have the same length along the first direction.

[0052] In this embodiment, as Figure 7 As shown, the overall shape of the second steel plate 2 is similar to an I-beam structure, such as... Figure 7As shown, the second steel plate 2 includes a connecting portion 21 and two steel sheet portions 22, two ends of the connecting portion 21 are connected with one steel sheet portion 22 respectively to form an I-shaped structure. A first U-shaped hole 23 is arranged on the connecting portion 21, a second U-shaped hole 24 is arranged on the steel sheet portion 22, and the length of the first U-shaped hole 23 along the first direction is less than the length of the second U-shaped hole 24 along the first direction. In addition, a third U-shaped hole 25 is arranged at the connecting end of the connecting portion 21 and the steel sheet portion 22, and the length of the third U-shaped hole 25 along the first direction is different on the left and right sides. In summary, on the second steel plate 2, it includes a second U-shaped hole 24, a third U-shaped hole 25, a plurality of first U-shaped holes 23, a third U-shaped hole 25, and a second U-shaped hole 24 in sequence along the second direction.

[0053] In this embodiment, as shown in Figure 4 and Figure 5 the first through hole 11 and the first U-shaped hole 23 correspondingly communicate to form a half-step hole 3, the second through hole 12 and the second U-shaped hole 24 correspondingly communicate to form a full-step hole 4, and the third U-shaped hole 25 and the third through hole 13 correspondingly communicate to form a transition hole 5. In actual application, as shown in Figure 3 there are two rows of stepped design holes on the printing steel mesh, and the two rows of holes are symmetrically distributed at a certain interval. Each row of holes includes a full-step hole 4, a transition hole 5, a plurality of half-step holes 3, a transition hole 5, and a full-step hole 4 in sequence along the second direction. It should be noted that in the half-step hole 3, the hole depth is not consistent, the hole depth at the position close to the connecting portion 21 is greater than the hole depth at the position away from the connecting portion 21, the hole depth at the position close to the connecting portion 21 = the thickness of the first steel plate 1 + the thickness of the second steel plate 2, and the hole depth at the position away from the connecting portion 21 = the thickness of the first steel plate 1. In the full-step hole 4, the hole depth of the full-step hole 4 is consistent, and the hole depth of the full-step hole 4 in the full-step hole 4 = the thickness of the first steel plate 1 + the thickness of the second steel plate 2.

[0054] In summary, the ladder type printing steel net provided by the utility model has the advantages that (1) the connector printing steel net opening is designed in steps, the advantages of the full-ladder type printing steel net and the half-ladder type printing steel net opening are combined, the first 2-3 groups of pin openings at the two ends of the connector are designed as full-ladder, and 10%-20% extension design is made, and the remaining pin openings in the middle are designed as half-ladder, and 10%-20% extension design is made. The advantages of this are: ① improving yield: optimizing tin paste distribution through step design, reducing short circuit and virtual welding. ② Reliability is enhanced: additional steel sheet increases local tin paste thickness, improves connector welding strength. ③ compatibility: does not affect the welding of surrounding components, can adapt to high-density PCB layout. (2) the first steel plate 1 is welded with the second steel plate 2 in the form of an I-shaped section after being opened, the connector opening position is thickened, the printing tin paste thickness at the connector opening is increased, the welding reliability is improved, and meanwhile the welding effect of surrounding components is not affected. The above is only an embodiment of the utility model, and does not limit the patent range of the utility model, and any equivalent transformation, direct or indirect application in related technical fields by using the contents of the utility model specification and drawings are also included in the patent protection range of the utility model.

Claims

1. A stepped printing screen, characterized in that The first steel plate is provided with a plurality of first openings, and the second steel plate is arranged on the first steel plate and above the vertical height direction of the first steel plate, and the second steel plate is provided with a plurality of second openings; wherein the first openings and the second openings are correspondingly arranged to form a plurality of half-step holes and a plurality of full-step holes.

2. The stepped printing screen of claim 1, wherein, The central part of the first steel plate is provided with a printing area, and the first openings are located on the printing area, and the second steel plate is welded on the printing area.

3. The stepped printing screen of claim 1 wherein, The second steel plate comprises a connecting part and two steel sheet parts, and the two ends of the connecting part are connected with the steel sheet parts respectively to form an I-shaped structure.

4. The stepped printing screen of claim 3, wherein, The second openings comprise first U-shaped holes and second U-shaped holes, the first U-shaped holes are located on the connecting part, and the second U-shaped holes are located on the steel sheet parts.

5. The stepped printing screen of claim 4, wherein, The first openings comprise first through holes and second through holes, the first through holes are correspondingly communicated with the first U-shaped holes to form the half-step holes, and the second through holes are correspondingly communicated with the second U-shaped holes to form the full-step holes.

6. The stepped printing screen of claim 5, wherein, The length of the first through hole along the first direction is greater than the length of the first U-shaped hole along the first direction, and the length of the second through hole along the first direction is equal to the length of the second U-shaped hole along the first direction.

7. The stepped printing screen of claim 5, wherein, The length of the first through hole along the first direction is equal to the length of the second through hole along the first direction, and the length of the first U-shaped hole along the first direction is less than the length of the second U-shaped hole along the first direction.

8. The stepped printing screen of claim 5, wherein, The first openings further comprise third through holes, and the second openings further comprise third U-shaped holes, the third U-shaped holes are correspondingly communicated with the third through holes to form the connecting holes.

9. The stepped printing screen of claim 1 wherein, The plurality of full-step holes are divided into two first hole groups, each first hole group comprises at least one full-step hole, the plurality of half-step holes comprise a second hole group, and the two first hole groups are symmetrically arranged on the two sides of the second hole group.

10. The stepped printing screen of claim 1, wherein, The thickness d1 of the first steel plate is 0.1mm≤d1≤0.15mm, and the thickness d2 of the second steel plate is 0.3mm≤d2≤0.5mm.

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