A BC component solder paste printing screen plate and printing device

Abstract

The utility model relates to photovoltaic module manufacturing technical field, more particularly to a kind of BC component tin paste printing screen and printing device.The BC component tin paste printing screen, including screen version body and the printing pattern being set on the screen version body;The printing pattern includes several mutually separated openings;The shape of the opening is the closed pattern with long axis and short axis.The BC component tin paste printing screen can reduce the usage amount of tin paste, improve module power, reduce the risk of soldering, hidden crack.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic module manufacturing technology, and more specifically, to a BC module solder paste printing screen and printing device. Background Technology

[0002] Back-contact solar modules, with all electrodes located on the back of the cells, eliminate shading losses from the front-side grid lines, resulting in higher conversion efficiency and a uniform, aesthetically pleasing appearance, making them a key development direction in the high-end photovoltaic market. However, all solder joints in BC modules are densely distributed on the back of the cells, placing extremely high demands on the precision and reliability of the soldering process.

[0003] Currently, in the manufacturing process of BC components, to ensure the soldering effect of the densely packed electrodes on the back side, the industry commonly uses dispensing solder paste printing technology. This technology can precisely apply solder paste to each electrode pad. The existing mainstream process mode is single-point printing, such as... Figure 1 As shown, each pad is printed with an individual solder paste dot, typically rectangular or circular in shape.

[0004] However, against the backdrop of continuous cost reduction and efficiency improvement in the photovoltaic industry, this single-point printing mode has gradually exposed its inherent technical shortcomings: First, there is a high risk of solder joint desoldering. To form sufficiently high solder joints during soldering to ensure connection strength, single-point printing requires applying a large amount of solder paste (e.g., approximately 150 mg / pcs). During reflow soldering, a large amount of solder paste reacts chemically with the silver in the cell electrodes, forming an excessively thick intermetallic compound layer. This compound layer is brittle, has poor wettability (a large wetting angle), and weak adhesion to the silicon substrate. Under subsequent thermal or mechanical stress, it is highly susceptible to detaching from the silicon surface, leading to solder joint failure and severely impacting the reliability and lifespan of the module.

[0005] Secondly, it leads to increased series resistance of the components and higher power loss. The intermetallic compound contains a large number of solid solutions and dislocation defects, and its resistivity is much higher than that of pure silver or pure tin. An excessively thick intermetallic compound layer is equivalent to introducing a high-resistivity region in the current path, increasing the series resistance of the components and thus causing a decrease in output power.

[0006] Furthermore, single-point printed solder paste patterns lack stress release space after melting, and the shrinkage stress generated during the curing process tends to concentrate in the silicon wafer area below the solder joint, posing a potential risk of inducing microcracks in the solar cell.

[0007] While some related technologies have been explored to address the above issues, fundamentally optimizing the distribution of solder paste to effectively reduce solder paste usage, inhibit the excessive growth of harmful intermetallic compounds, and reduce soldering stress while ensuring soldering strength remains a pressing technical challenge in this field.

[0008] In view of the above, this utility model is hereby proposed. Utility Model Content

[0009] The present invention provides a BC component solder paste printing stencil and printing device. The BC component solder paste printing stencil can reduce the amount of solder paste used, increase component power, and reduce the risk of desoldering and microcracks.

[0010] In order to achieve the above-mentioned objectives of this utility model, the following technical solution is adopted: A BC component solder paste printing screen includes a screen body and a printed pattern disposed on the screen body; The printed pattern includes several mutually separate openings; The opening is a closed shape with a major axis and a minor axis.

[0011] The BC component solder paste printing stencil, by optimizing the single-point printing pattern and changing it to an elliptical double-point printing pattern, reduces the amount of solder paste printed. In actual measurements, this has decreased from 150mg / pcs to 100mg / pcs, resulting in reduced solder paste consumption and a significant reduction in desoldering. This also reduces the solder paste printing area and lowers the risk of microcracks in the solder joints.

[0012] The BC component solder paste printing stencil, with its double-point elliptical pattern, increases the free area at the solder joints, allowing for sufficient space during soldering and providing room for the solder paste to melt and deform, thus greatly reducing the risk of microcracks during soldering. It also significantly reduces the content of intermetallic compounds during soldering, lowering the risk of desoldering. Intermetallic compounds contain a large amount of solid solution and dislocations, resulting in high electrical resistance. Therefore, this invention reduces solder joint resistance and increases component power by improving the printing pattern. Furthermore, improving the printing pattern reduces solder paste loss by approximately 50%.

[0013] Preferably, the shape of the opening includes an ellipse.

[0014] Preferably, each of the printed patterns includes two of the openings.

[0015] Preferably, the major axes of the two openings are parallel to each other.

[0016] Preferably, the two openings are arranged along their long axis, and the minimum interval L between them is 0.02~0.08mm. Preferably, the two openings are arranged symmetrically with respect to the center of the printed pattern in which they are located.

[0017] Preferably, the minor axis length of the opening is 0.3~0.56mm.

[0018] Preferably, the major axis length of the opening is 0.4~0.9mm.

[0019] Preferably, the thickness of the mesh body is 80~120µm.

[0020] A BC component solder paste printing apparatus includes the aforementioned BC component solder paste printing screen.

[0021] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. Significantly reduces solder paste usage and production costs. By changing the single-point pattern to a two-point split pattern, the distribution of solder paste on the pads was optimized, resulting in a significant reduction in solder paste usage while maintaining soldering strength. Actual test data shows that the wet weight of solder paste per solder joint was reduced from approximately 150 mg / pcs to approximately 100 mg / pcs, a reduction of about one-third, directly lowering the high cost of silver paste consumables for BC components.

[0022] 2. Significantly improves welding reliability and reduces the risk of weld failure. This invention reduces the total amount of solder paste at individual solder joints, thereby fundamentally reducing the total amount of Sn element reacting with the silver electrode layer during reflow soldering, effectively suppressing the excessive growth of the brittle intermetallic compound layer. This results in a moderately thick and more robust IMC layer, fundamentally reducing the risk of solder joint detachment due to poor wettability and weak adhesion of the IMC layer, and greatly improving the long-term reliability of the component.

[0023] 3. Optimize welding stress distribution to reduce the occurrence of microcracks. The dual-point separation graphic design creates a natural stress relief zone between the solder joints. When the solder paste melts and solidifies during the soldering process, the resulting shrinkage stress is buffered and redistributed in the empty area, avoiding excessive stress concentration at a single point. This greatly reduces the risk of microcracks in the battery cells during the soldering process and improves product yield.

[0024] 4. Improve electrical performance and increase component output power. Because intermetallic compounds have relatively high electrical resistance, this invention effectively reduces the series resistance at the solder joints by decreasing their formation. This reduces current loss during transmission, ultimately resulting in an increase in the module's fill factor and maximum output power, bringing additional performance gains to the module.

[0025] 5. Provides process redundancy and enhances operator friendliness. The separate graphic design allows for more space for the solder paste to flow and deform during the melting process, providing a larger process window margin and better tolerance for minor deviations in the printing and soldering processes, making the process more stable, easier to implement and control.

[0026] In summary, this utility model, through ingenious screen printing innovation, simultaneously achieves the three major goals of cost reduction, efficiency improvement, and quality enhancement, effectively resolving the long-standing contradiction between welding reliability and cost in BC component manufacturing, and promoting the further development and application of BC technology. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a single-dot printing screen structure; Figure 2 This is a schematic diagram of a two-dot printing screen.

[0029] Figure label: 1-Network version body, 2-Opening. Detailed Implementation

[0030] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are only some embodiments of this utility model, not all embodiments, and are only used to illustrate this utility model, and should not be regarded as limiting the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0031] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0033] A BC component solder paste printing screen includes a screen body 1 and a printed pattern disposed on the screen body 1; The printed pattern includes several mutually separated openings 2; The opening 2 is a closed shape with a major axis and a minor axis.

[0034] The separated opening 2 pattern on the BC component solder paste printing stencil changes the accumulation pattern of solder paste on the pads, which can effectively reduce the total amount of solder paste printed on a single solder joint while ensuring the strength of the solder joint. In actual tests, it can reduce the amount of solder paste from 150mg / pcs to 100mg / pcs, directly reducing production costs.

[0035] By reducing the amount of solder paste per unit area, the formation of excessive brittle intermetallic compounds during the soldering process is fundamentally suppressed, thereby reducing the risk of desoldering due to poor adhesion of the compound layer and enhancing the long-term reliability of BC components.

[0036] The mutually separated opening 2 structure forms a natural buffer area between the solder joints, leaving space for the solder paste to melt and deform, which can effectively absorb and release the welding thermal stress and significantly reduce the probability of microcracks in the cell caused by this.

[0037] By reducing the amount of high-resistivity intermetallic compounds formed, this invention helps to reduce the contact resistance at the solder joints, thereby improving the fill factor and final output power of the BC assembly.

[0038] Furthermore, the opening 2 is elliptical in shape. This design gives the opening 2 a smooth, continuous edge without sharp corners. This facilitates the smooth filling and release of solder paste under the action of the squeegee, reduces stress concentration and solder paste residue caused by sharp corners of the pattern, thereby ensuring the integrity and consistency of the printed solder paste pattern and further reducing the risk of desoldering and microcracks.

[0039] Furthermore, each of the printed patterns includes two openings 2. This arrangement forms the core of "two-point" printing. It rationally distributes the amount of solder paste that would otherwise be concentrated at a single point to two points, significantly reducing the local accumulation of solder paste at each point without reducing the total connection area. This directly results in savings in solder paste usage and creates structural conditions for stress release during soldering and for reducing intermetallic compounds.

[0040] Furthermore, the major axes of the two openings 2 are parallel to each other. This arrangement ensures that the orientation of the two openings 2 is consistent, guaranteeing a regular layout of the solder paste pattern on the BC component electrodes. This orderly arrangement facilitates the uniform distribution of heat and stress during soldering, avoiding irregular soldering or stress concentration that may result from random orientation, and improving process stability and the uniformity of solder joint quality.

[0041] Furthermore, the two openings 2 are arranged along their long axis, and the minimum spacing L between them is 0.02~0.08mm. This arrangement ensures the effectiveness of the two-point structure by defining a precise spacing range. Too small a distance may cause solder paste to bridge during printing or melting, negating the advantages of the two-point design; too large a distance would make the two solder points too independent, weakening their synergistic effect in providing electrical connection and mechanical fixation. This range perfectly balances the dual objectives of "separation to release stress" and "synergy to ensure connection."

[0042] Furthermore, the two openings 2 are symmetrically arranged with respect to the center of their respective printed patterns. This arrangement allows the solder paste to form symmetrically distributed solder joints on the pads. This symmetrical structure ensures that the shrinkage stress generated after soldering is evenly distributed towards the center or in multiple directions, avoiding unilateral stress concentration caused by asymmetrical layout, thereby more effectively protecting the battery cells, reducing the risk of microcracks, and improving the mechanical strength of the solder joints.

[0043] Furthermore, the minor axis length of the opening 2 is 0.3~0.56mm. This setting directly controls the cross-sectional area of ​​a single solder paste dot by limiting the width of the opening 2. This range ensures that a sufficiently wide conductive channel is formed to carry the operating current, while avoiding an excessively long minor axis (i.e., an excessively wide opening 2) which would result in an excessively large solder paste spreading area, thereby increasing the risk of microcracks or bridging with adjacent solder joints.

[0044] Furthermore, the major axis length of the opening 2 is 0.4~0.9mm. This setting, by limiting the length of the opening 2, achieves precise control of the amount of solder paste used while ensuring sufficient contact area with the electrode to provide good mechanical strength. This range ensures that the solder joint has the necessary elongated shape to facilitate stress release, while preventing solder paste waste and increased resistance due to excessive length.

[0045] Furthermore, the thickness of the screen printing body 1 is 80~120µm. This setting directly determines the thickness and volume of the printed solder paste. This thickness range is the result of optimization: too thin a thickness will result in insufficient solder paste, affecting the soldering strength; too thick a thickness will result in excessive solder paste, returning to the drawbacks of traditional single-point printing, increasing the risk of desoldering and material costs. This range is one of the key process parameters for achieving the goal of low solder paste consumption and high soldering reliability of this utility model.

[0046] A BC component solder paste printing apparatus includes the aforementioned BC component solder paste printing screen.

[0047] The BC component solder paste printing device uses a stencil with an optimized opening pattern (2). This device can stably print solder paste patterns on BC components with lower risks of desoldering and microcracks, directly improving the yield and reliability of the final product. The printing process using this device significantly reduces solder paste consumption per unit product, thereby lowering raw material costs in continuous production and improving the economic efficiency of the device operation. This device integrates core structural innovations into the stencil component, enabling the entire device to perform a more advanced and reliable BC component solder paste printing process, enhancing its technological advantage in the market. The stencil, as a core consumable component of the device, has a unique and easily replaceable structural design. When maintenance or process upgrades are required, simply replacing this specific stencil allows the entire device to obtain all the technological advantages brought by this invention, resulting in simple operation and low maintenance costs.

[0048] Example 1 The BC component solder paste printing screen provided in this embodiment, such as Figure 2 As shown, it includes a screen print body 1 and printed graphics set on the screen print body 1; The printed graphic includes two separate openings 2; The shape of opening 2 is elliptical; The two openings 2 are arranged along their long axis, and the minimum interval L between them is 0.05 mm; The two openings 2 are symmetrically arranged with respect to the center of the printed graphic in which they are located; The minor axis of opening 2 is 0.48 mm; the major axis of opening 2 is 0.7 mm. The thickness of web version 1 is 80. μm .

[0049] Example 2 The BC component solder paste printing apparatus provided in this embodiment includes the BC component solder paste printing screen of Embodiment 1.

[0050] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A BC assembly solder paste printing screen, characterized by, The printing graphic comprises a plurality of mutually separated openings. The shape of the opening is a closed graphic with a long axis and a short axis. The shape of the opening comprises an ellipse.

2. The BC assembly paste printing screen according to claim 1, wherein, Each of the printing graphics comprises two openings.

3. The BC assembly paste printing screen according to claim 1, wherein, The long axes of the two openings are parallel to each other.

4. The BC assembly paste printing screen according to claim 3, wherein, The two openings are arranged along their long axes, and the minimum distance L between them is 0.02-0.08 mm.

5. The BC assembly paste printing screen according to claim 4, wherein, The two openings are symmetrically arranged relative to the center of the printing graphic in which they are located.

6. The BC assembly paste printing screen according to claim 3, wherein, The short axis length of the opening is 0.3-0.56 mm.

7. The BC assembly paste printing screen according to claim 1, wherein, The long axis length of the opening is 0.4-0.9 mm.

8. The BC assembly paste printing screen according to claim 1, wherein, The thickness of the screen version body is 80-120 µm.

9. The BC assembly paste printing screen according to claim 1, wherein, The BC component solder paste printing screen claimed in any one of claims 1-9.

10. A BC assembly paste printing apparatus, characterized by, ​

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