A side-mounted pad processing method

Abstract

The present invention discloses a side-mounted pad processing method. During the PCB cutting process, the cutting knife's path along a row of tin-plated holes is a concave-convex wavy line path. The present invention designs the cutting path into a concave-convex wavy line path, which can avoid the influence of processing errors on the thickness of solder paste, thereby avoiding undesirable phenomena such as yin-yang surface, tin explosion, cold soldering, and lamp bead position deviation.

Description

Technical Field

[0001] The invention relates to the technical field of LED transparent screens, and in particular to a side-mounted solder pad processing method. Background Art

[0002] As a branch of LED display screens, LED transparent screens are used in more and more occasions. There are two main branches of LED transparent screens, the first is front-mounted side-emitting, and the second is side-mounted front-emitting. The former requires special lamp beads and is expensive, so it has almost been eliminated. The latter has advantages such as lower prices and the use of ordinary lamp beads, and is becoming more and more mainstream. However, the existing side-mounted front-emitting technology has the problem of uneven solder paste thickness, as follows:

[0003] like Figure 1 As shown, taking PCB 4 panels as an example, there are long waist holes designed between 1 and 2, 3 and 4, and they are made into tin-plated holes 01. After the PCB is made, the board is separated. Figure 2 Similarly, use the milling cutter to cut between 1 and 2, 2 and 3, and 3 and 4 (the mesh shadow in the figure is the tool path 02), so as to divide the puzzle into small boards such as 1, 2, 3, and 4. Figure 3 .like Figure 4-5 As shown in the figure, let the diameter of the milling cutter be A, the width of the tin-plated hole be B, and ∆ be the tool path tolerance. Then the PCB must ensure that B≥A+∆, otherwise the pad will be broken off and the PCB will be scrapped. The final processed PCB will have a variety of PCBs due to the difference in positive and negative tolerances, such as Figure 6 , take the two states of maximum positive tolerance and minimum negative tolerance to illustrate.

[0004] like Figure 7 When the PCB has a positive tolerance, the distance between pad 03 and the upper surface of the PCB is s, and the thickness of the steel mesh is m, then the thickness of the scraped solder paste = s + m; when the PCB has a negative tolerance, pad 03 is flush with the upper surface of the PCB, and the thickness of the steel mesh is m, then the thickness of the scraped solder paste = m; so when the PCB has a positive tolerance or a negative tolerance, there will be many types of PCBs and many types of solder paste thicknesses, which will cause adverse phenomena such as yin and yang surfaces, tin explosion, cold soldering, and lamp bead misalignment. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a side-mounted pad processing method, which effectively eliminates product defects caused by processing errors, thereby effectively increasing product yield and reducing the difficulty of production process.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A side-mounted pad processing method, during the PCB cutting process, the cutting knife's path along a row of tin-plated holes is a concave-convex wavy line path.

[0008] Furthermore, the convex portion of the concave-convex wavy line track extends into the tin-plated hole.

[0009] Furthermore, pad identification positions are respectively provided at the extreme negative tolerance positions on the upper and lower sides of the tin-plated hole. After cutting is completed, if the pad identification position is retained, it is determined that the processing tolerance is within the design range; if the pad identification position disappears, the processing tolerance exceeds the design range.

[0010] The present invention adopts the above technical solution and has the following beneficial technical effects:

[0011] 1. The cutting path is designed into a concave and convex wave line trajectory, which can avoid the influence of processing errors on the thickness of solder paste, and thus avoid the undesirable phenomena such as yin and yang surface, tin explosion, cold soldering, and lamp bead deviation;

[0012] 2. The pad has a pad identification position, which can quickly determine the impact of processing errors on the product (i.e. good product determination). BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments;

[0014] Figure 1 This is a schematic diagram of a PCB with a 4-panel structure;

[0015] Figure 2 This is a schematic diagram of cutting and dividing the PCB into panels;

[0016] Figure 3 This is a schematic diagram after PCB cutting and splitting;

[0017] Figure 4 This is a schematic diagram of the dimensions of the milling cutter diameter and the tin-plated hole width on the PCB;

[0018] Figure 5 This is a schematic diagram of the dimensions of the milling cutter diameter, tinning hole width and tolerance on the PCB;

[0019] Figure 6 A schematic diagram of the two states of the PCB taking the maximum positive tolerance and the minimum negative tolerance;

[0020] Figure 7 This is a schematic diagram of the thickness of solder paste scraped when the PCB is running with positive tolerance and negative tolerance;

[0021] Figure 8 Schematic diagram of pad identification position in the present invention;

[0022] Fig. 9A schematic diagram of the cutting path of the present invention;

[0023] Fig.10 for Fig. 9 A in the enlarged view;

[0024] Fig.11 It is a schematic diagram of the two extreme states of positive tolerance and negative tolerance of PCB after adopting the processing method of the present invention. DETAILED DESCRIPTION

[0025] Please refer to Figure 8-11 The present invention provides a side-mounted pad processing method: during the cutting process of PCB1, the cutting trajectory of the cutting tool (milling cutter) along a row of tin-plated holes 2 is a concave-convex wavy line trajectory 5, and the specific concave-convex amount and concave-convex position are designed in detail according to different products.

[0026] As an implementation mode, in this embodiment, the convex part of the concave-convex wavy line track 5 extends into the tin-plated hole 2. Taking the plate numbered a as an example, after the plate is divided, according to the positive tolerance and the negative tolerance, each limit state is selected for analysis, see Fig.11 The height of pad 4 is consistent. It is just because of the tolerance difference that there are local differences in the PCB. This difference does not affect the attachment of the steel mesh. Therefore, regardless of positive or negative tolerance, the final thickness of the solder paste is consistent (the thickness is m). This can solve the problems caused by inconsistent solder paste thickness, such as yin and yang surfaces, tin explosion, cold soldering, and lamp bead position deviation.

[0027] In addition, pad identification positions 3 are respectively provided at the extreme negative tolerance positions on the upper and lower sides of the tin-plated hole 2. After the cutting is completed, if the pad identification position 3 is retained, it is determined that the processing tolerance is within the design range and has no performance impact on the PCB; if the pad identification position 3 disappears, the processing tolerance exceeds the design range and has affected the PCB performance.

[0028] The implementation of the present invention is described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes. The above-mentioned specific implementation modes are illustrative rather than limiting the present invention. Those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A side-mounted pad processing method, characterized in that: During the PCB cutting process, the cutting knife's trajectory along a row of tin-plated holes is a concave-convex wavy line trajectory; the convex part of the concave-convex wavy line trajectory extends into the tin-plated holes; the upper and lower extreme negative tolerance positions of the tin-plated holes are respectively provided with pad identification positions. After the cutting is completed, if the pad identification position is retained, it is determined that the processing tolerance is within the design range; if the pad identification position disappears, the processing tolerance exceeds the design range; the final thickness of the solder paste is consistent.

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