Steel mesh structure

Abstract

The utility model discloses a steel mesh structure which comprises a steel mesh body. The multiple first steel mesh openings are formed in the steel mesh body, and a rectangular frame is defined by the multiple first steel mesh openings; the second steel mesh openings are formed in the steel mesh body and located in the rectangular frame; the area of the opening of the first steel mesh is larger than that of the opening of the second steel mesh. According to the utility model, the welding problems of weld leg displacement, welding spot void, pseudo soldering and the like on the welding surface, which are caused by the fact that the surface tension of soldering tin is large when the soldering tin passes through a high-temperature area and the soldering tin is gathered and extruded towards the center to form a hollow cavity, can be effectively avoided; the drawing stress of the male and female head terminals of the connector for multiple times in actual application to the bonding pad is improved, and the use reliability after the connector is pulled and plugged for multiple times is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of PCB welding, in particular to a steel mesh structure. Background Art

[0002] With the development of high-frequency and high-speed PCB (printed circuit board) design and processing industry, there are more and more high-frequency and high-speed electronic components in PCB, and the size of PCB is getting smaller and smaller. There is an urgent need for smaller components to alleviate the problem of insufficient PCB layout space. Among them, high-frequency connectors are also getting smaller in size, and the number of connector pads and the Pitch (center spacing) density between pads show a clear upward trend. At present, 5.08mm and 2.54mm Pitch SMD (surface mount device) pad connectors can no longer meet the small size requirements, so high-frequency connectors with 1.27mm Pitch 0.635mm diameter circular SMD pads are gradually becoming the mainstream.

[0003] Due to the reduction in connector pad size and pitch density, in the actual SMT reflow production process, the existing steel mesh structure is designed according to the device pad structure, and then used for connector welding. In the high temperature zone of reflow, due to the large surface tension of the solder, the solder is squeezed inward to the center to form a hollow cavity, causing solder foot displacement, solder joint voids, cold solder joints and other welding problems on the welding surface, resulting in low connector welding yield and poor welding reliability during reflow, thus affecting the high-frequency performance of the connector during testing and use. At the same time, during the use of the connector, the male and female heads need to be plugged and unplugged many times, and are subject to repeated thermal stress, which can easily cause pit cracks (createring) defects at the pad welding point, resulting in connector failure and ultimately affecting the overall performance of the circuit board. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, the utility model provides a steel mesh structure to solve the problems of solder foot displacement, solder joint voids, pad cracks, etc. caused by steel mesh structure problems during the reflow soldering process of high-frequency connectors of circular diameter SMD pads in the prior art.

[0005] In order to achieve the above and other purposes, the utility model provides a steel mesh structure, including:

[0006] Steel mesh body;

[0007] A plurality of first steel mesh openings are arranged on the steel mesh body, and the plurality of first steel mesh openings are surrounded to form a rectangular frame;

[0008] A plurality of second steel mesh openings are arranged on the steel mesh body and are located within the rectangular frame;

[0009] The area of ​​the opening of the first steel mesh is greater than the area of ​​the opening of the second steel mesh.

[0010] In an embodiment of the present invention, the shape of the opening of the first steel mesh is one of a quadrilateral and an octagon.

[0011] In an embodiment of the present invention, the opening of the second steel mesh is circular in shape.

[0012] In one embodiment of the utility model, the shape of the opening of the first steel mesh is an octagon, wherein the octagon includes 4 main sides and 4 oblique sides, and the 4 main sides and the 4 oblique sides are arranged alternately; the length of the main side is 0.7 mm, the length of the oblique side is 0.707 mm, the angle between the main side and the oblique side is 45 degrees, and the distance between the centers of two adjacent first steel mesh openings is 1.27 mm.

[0013] In one embodiment of the present invention, a plurality of the second steel mesh openings are arranged in an array in the rectangular frame, wherein the diameter of the second steel mesh opening is 0.7 mm, and the distance between the centers of two adjacent second steel mesh openings is 1.27 mm.

[0014] In an embodiment of the present invention, the steel mesh structure further includes: a first positioning hole, which is disposed at one end of the steel mesh body.

[0015] In one embodiment of the present invention, the steel mesh structure further includes: a second positioning hole, which is arranged at the other end of the steel mesh body, and the first positioning hole and the second positioning hole are arranged at two opposite ends of the steel mesh body.

[0016] In an embodiment of the present invention, the diameters of the first positioning hole and the second positioning hole are both 0.7 mm.

[0017] In an embodiment of the present invention, the thickness of the steel mesh body is 0.15 mm.

[0018] Beneficial effects of the utility model:

[0019] The utility model provides a steel mesh structure, including: a steel mesh body; a plurality of first steel mesh openings, which are arranged on the steel mesh body, and the plurality of first steel mesh openings are enclosed to form a rectangular frame; a plurality of second steel mesh openings, which are arranged on the steel mesh body and are located in the rectangular frame; the area of ​​the first steel mesh openings is larger than the area of ​​the second steel mesh openings. The utility model can effectively avoid the soldering problems such as solder foot displacement, solder joint voids, and cold solder joints on the soldering surface caused by the large surface tension of the solder in the high temperature zone during the actual SMT reflow soldering production and processing, and improve the pulling stress of the male and female terminals of the connector on the solder pad after multiple plugging and unplugging in actual applications, and ensure the reliability of the connector after multiple plugging and unplugging.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0022] Figure 1 A schematic diagram of a steel mesh structure according to an embodiment of the present utility model;

[0023] Figure 2 A schematic diagram of the opening of the first steel mesh according to an embodiment of the present utility model;

[0024] Figure 3 A schematic diagram of the opening of the first steel mesh according to an embodiment of the present utility model;

[0025] Figure 4 The void problem found by X-ray photography after reflow soldering of the existing steel mesh structure;

[0026] Figure 5 Solder displacement problem found by X-ray photography after reflow soldering of existing steel mesh structure;

[0027] Figure 6 This is an X-ray photograph of the steel mesh structure after reflow soldering in one embodiment of the utility model;

[0028] Figure 7 3D simulation picture of mechanical tensile stress of existing structure;

[0029] Figure 8 This is a picture of the simulation results of mechanical tensile stress of the existing structure;

[0030] Fig. 9 This is a 3D simulation picture of the mechanical tensile stress of the steel mesh structure of an embodiment of the utility model;

[0031] Fig.10 This is a picture of the mechanical tensile stress simulation results of the steel mesh structure of one embodiment of the utility model. DETAILED DESCRIPTION

[0032] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations. The details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0033] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0034] Although the terms "first", "second", "A", "B", etc. may be used herein to describe various elements, these elements should not be limited by these terms and are only used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of the following technology. The term "and / or" includes a combination of multiple related items or any item in the multiple related items.

[0035] As used herein, unless the context indicates otherwise, the singular form is intended to include the plural form, and it will be understood that the term "comprising" means the presence of stated features, quantities, steps, operations, elements, or combinations thereof, but does not exclude the presence or addition of one or more other features, quantities, steps, operations, elements, components, or combinations thereof.

[0036] Before describing the drawings in detail, it is intended to clarify that the division of components in this specification is divided only by the main function of each component. That is, two or more components to be described below can be combined into one component, or can be divided into two or more components according to more detailed functions. In addition to the main function of the component, each component to be described below can also perform some or all of the functions of other components, and some of the main functions of each component can be exclusively performed by other components.

[0037] The existing steel mesh structure is designed according to the connector pad structure, and the steel mesh is used for connector welding. However, due to the large surface tension of the solder in the high temperature area of ​​the reflow soldering, the solder is squeezed inward to form a hollow cavity, causing welding problems such as solder foot displacement, solder joint voids, and cold solder joints on the welding surface. Figure 4 Figure 5 As shown, the connector has a low soldering yield rate during reflow soldering. During the use of the connector, the male and female heads need to be plugged and unplugged many times, and are subjected to repeated thermal stress, resulting in pit cracks (createring) defects at the pad welding site, which causes the circuit board to fail and the connector has poor reliability. Based on this, the utility model provides a steel mesh structure, which is mainly aimed at high-frequency connectors with a 1.27mm pitch 0.635mm diameter circular pad structure. Through the steel mesh structure, it is possible to effectively avoid the solder surface tension being large in the high temperature zone during the actual SMT reflow soldering production and processing, and the solder is squeezed inwardly to the center to form a hollow cavity, causing solder foot displacement on the welding surface, solder joint voids, cold solder joints and other welding problems, thereby improving the pull-out stress of the male and female terminals of the connector on the pad when plugged and unplugged many times in actual applications, and ensuring the reliability of the connector after plugging and unplugging many times.

[0038] See also Figure 1 , Figure 1 A steel mesh structure according to an embodiment of the present invention comprises:

[0039] Steel mesh body 1;

[0040] A plurality of first steel mesh openings 2 are arranged on the steel mesh body 1, and the plurality of first steel mesh openings 2 are surrounded to form a rectangular frame;

[0041] A plurality of second steel mesh openings 3 are arranged on the steel mesh body 1 and are located within the rectangular frame;

[0042] The area of ​​the first steel mesh opening 2 is larger than the area of ​​the second steel mesh opening 3 .

[0043] In one embodiment, the shape of the opening of the first steel mesh is a quadrilateral or an octagon.

[0044] See also Figure 2 , Figure 2This is a schematic diagram of the first steel mesh opening of an embodiment of the present application. The shape of the first steel mesh opening is an octagon, wherein the octagon includes 4 straight sides and 4 oblique sides, and the 4 straight sides and the 4 oblique sides are arranged alternately; the length of the straight side is 0.7mm, the length of the oblique side is 0.707mm, the angle between the straight side and the oblique side is 45 degrees, and the distance between the centers of two adjacent first steel mesh openings is 1.27mm. In this embodiment, the area of ​​the first steel mesh opening is 0.635 square millimeters, and the amount of tin on the corresponding pad after the steel mesh is brushed with tin is 0.09525 cubic millimeters. Figure 2 As shown, there are 40 first steel mesh openings in the horizontal direction of the X-axis and 10 first steel mesh openings in the vertical direction of the Y-axis, for a total of 96.

[0045] In one embodiment, the opening of the second steel mesh is circular in shape.

[0046] See also Figure 3 , Figure 3 Schematic diagram of the second steel mesh opening according to an embodiment of the present application. Figure 3 In the embodiment, a plurality of the second steel mesh openings are arranged in an array in the rectangular frame, wherein the diameter of the second steel mesh openings is 0.7 mm, and the distance between the centers of two adjacent second steel mesh openings is 1.27 mm. Figure 3 As shown, the second steel mesh has a total of 304 openings. The area of ​​each second steel mesh opening is 0.385 square millimeters, and the corresponding tin amount after the steel mesh is tinned is 0.0577 cubic millimeters.

[0047] In one embodiment, the steel mesh structure further includes: a first positioning hole 4, which is arranged at one end of the steel mesh body.

[0048] In one embodiment, the steel mesh structure further includes: a second positioning hole 5, which is arranged at the other end of the steel mesh body, and the first positioning hole and the second positioning hole are arranged at two opposite ends of the steel mesh body.

[0049] In one embodiment, the diameters of the first positioning hole and the second positioning hole are both 0.7 mm.

[0050] In one embodiment, the thickness of the steel mesh body is 0.15 mm.

[0051] The utility model increases the area of ​​the first octagonal steel mesh opening and the circular second steel mesh opening, so that the amount of tin applied to the outermost and inner pin pads during connector welding is increased, thereby effectively avoiding problems such as solder joint voids. The circular positioning holes (first positioning holes and second positioning holes) with a diameter of 0.7mm on both sides are combined with the increase in the amount of tin applied to all pads to avoid the problem of poor welding of the pin pads around the connector due to slight offset when the connector passes through the reflow furnace. The utility model can correct slight offsets in all directions of the connector, effectively avoiding the problem of cold solder joints at the outermost edge, thereby improving the overall welding yield rate.

[0052] At the same time, the opening of the outermost first steel mesh is designed to be an octagonal structure with a larger area than the conventional circular structure, so that the amount of tin on the outermost pin pad is increased, which can effectively reduce the need for multiple plugging and unplugging of the male and female heads during the use of the connector, and the repeated thermal stress will cause pitting (createring) problems at the pad welding. Through X RAY image data analysis, the pitting and cracking phenomenon at the pad welding occurs in the outermost welding. The welding structure of the outermost single connector terminal is 3D modeled through mechanical structure simulation software. The existing steel mesh structure mechanical pull-out stress 3D simulation picture is as follows Figure 7 As shown in the figure, the stress result obtained by simulation is 4.9281N. Figure 8 The existing steel mesh structure is simulated multiple times through iterations, and the optimization result is the 3D simulation picture of the mechanical tensile stress of the steel mesh structure provided by the utility model. Fig. 9 As shown in Figure 2, the stress result obtained through simulation is 15.541N. Fig.10 The mechanical pulling stress of the steel mesh structure provided by the utility model is increased by 10.6129N on the basis of the original structure.

[0053] During the actual verification process, no welding problems such as cracks at the pad welding, solder foot displacement, solder joint voids, and cold solder joints occurred. Figure 6 The utility model effectively improves the reliability of the connector.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by a person with ordinary knowledge in the relevant technical field without departing from the spirit and technical ideas disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A steel mesh structure, characterized in that: include: Steel mesh body; A plurality of first steel mesh openings are arranged on the steel mesh body, and the plurality of first steel mesh openings are surrounded to form a rectangular frame; A plurality of second steel mesh openings are arranged on the steel mesh body and are located within the rectangular frame; The area of ​​the opening of the first steel mesh is greater than the area of ​​the opening of the second steel mesh; The shape of the opening of the first steel mesh is an octagon, wherein the octagon includes 4 positive sides and 4 oblique sides, and the 4 positive sides and the 4 oblique sides are arranged alternately; the length of the positive side is 0.7 mm, the length of the oblique side is 0.707 mm, the angle between the positive side and the oblique side is 45 degrees, and the distance between the centers of two adjacent first steel mesh openings is 1.27 mm; The shape of the second steel mesh opening is circular; a plurality of the second steel mesh openings are arranged in an array in the rectangular frame, wherein the diameter of the second steel mesh opening is 0.7 mm, and the distance between the centers of two adjacent second steel mesh openings is 1.27 mm; The steel mesh structure further includes: a first positioning hole, which is arranged at one end of the steel mesh body; The steel mesh structure further includes: a second positioning hole, which is arranged at the other end of the steel mesh body, and the first positioning hole and the second positioning hole are arranged at two opposite ends of the steel mesh body.

2. The steel mesh structure according to claim 1, characterized in that: The diameters of the first positioning hole and the second positioning hole are both 0.7 mm.

3. The steel mesh structure according to claim 1, characterized in that: The thickness of the steel mesh body is 0.15 mm.

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