Solder resist windowing structure for patch elements

Abstract

This utility model discloses a solder mask opening structure for surface mount components, relating to the field of printed circuit board design technology. The solder mask opening structure for surface mount components includes a printed circuit board, which comprises a solder mask layer and a metal layer. A solder mask opening is provided on the solder mask layer. The metal layer is connected to the solder mask layer, and a first pad and a second pad are provided on the side of the metal layer facing the solder mask layer. The technical solution of this utility model fully considers the characteristics of small pad spacing and tiny solder shoulder size of 01005 surface mount components. By eliminating the solder mask bridge between the first and second pads, the first and second pads are fully exposed within the solder mask opening. Furthermore, by controlling the reasonable gap between the outer walls of the first and second pads and the inner wall of the solder mask opening, the solder paste printing and soldering process is optimized, fundamentally solving common problems such as solder balls, tombstoning, and cold solder joints in the SMT soldering process of 01005 surface mount components.

Description

Technical Field

[0001] This utility model relates to the field of printed circuit board design technology, and in particular to a solder resist window structure for surface mount components. Background Technology

[0002] With the continuous miniaturization of electronic products, 01005 surface mount components, due to their small size and high integration, are widely used in high-end electronic products, especially in the EMS (Electronics Manufacturing Services) electronic assembly field, where their application rate exceeds 95%. However, the extremely small size of 01005 surface mount components (length and width dimensions of only 0.4mm × 0.2mm), coupled with an extremely narrow process window, places stringent requirements on the manufacturability of the pad design. Traditional packaging designs are no longer sufficient to meet the process requirements of miniaturized components. In SMT (Surface Mount Technology) processes, the phenomenon of "solving solder ball problems easily leading to open circuits and tombstoning" or "overcoming open circuits and tombstoning exacerbating solder ball problems" often occurs, which are contradictory and significantly increase the soldering defect rate. The resulting high defect rate not only increases rework costs but also affects product quality and delivery cycle, causing significant losses to the SMT production line.

[0003] Solder ball defects are one of the major defects in surface mount technology (SMT), with complex causes and difficulty in control. According to the Electronic Component Acceptability Standard (IPC-A-610J), solder ball size must not violate minimum electrical clearances; for 01005 surface mount components, this standard requires zero tolerance for solder balls. Solder balls typically range in diameter from 0.1mm to 0.4mm, or even larger, and are commonly found on the sides of surface mount resistors and capacitors, and sometimes near IC (Integrated Circuit) or connector pins. Solder balls not only affect the product's appearance but can also detach during use, causing short circuits and seriously affecting the functionality and safety of electronic products. Utility Model Content

[0004] The main purpose of this invention is to propose a solder mask window structure for surface mount components, which aims to solve the soldering defects such as solder balls, tombstoning, and cold solder joints generated by 01005 surface mount components in the SMT process.

[0005] To achieve the above objectives, this utility model proposes a solder mask opening structure for surface mount components. The solder mask opening structure for surface mount components includes a printed circuit board, which comprises:

[0006] A solder resist layer, wherein a solder resist window is provided on the solder resist layer;

[0007] A metal layer is connected to the solder mask layer, and the metal layer and the solder mask layer are arranged sequentially along a first direction. A first pad and a second pad are provided on the side of the metal layer facing the solder mask layer. Both the first pad and the second pad are exposed through the solder mask opening. The first pad and the second pad are arranged at intervals along a second direction. There is a gap between the outer wall of the first pad and the inner wall of the solder mask opening, and there is a gap between the outer wall of the second pad and the inner wall of the solder mask opening. The first direction is perpendicular to the second direction.

[0008] The first pad is used for electrical connection with the first solder shoulder of the surface mount component, and the area of ​​the first pad is larger than the area of ​​the first solder shoulder. The second pad is used for electrical connection with the second solder shoulder of the surface mount component, and the area of ​​the second pad is larger than the area of ​​the second solder shoulder.

[0009] In one embodiment, the spacing between the first pad and the second pad is defined as G, then G = 0.16 mm.

[0010] In one embodiment, the two ends of the solder mask opening that are disposed opposite to each other along the second direction are a first end and a second end, respectively, with the first pad disposed near the first end and the second pad disposed near the second end;

[0011] If a first gap A1 is defined between the side of the first pad away from the second pad and the first end, then: A1 = 0.05 mm;

[0012] And / or,

[0013] If a second gap A2 is defined between the side of the second pad away from the first pad and the second end, then A2 = 0.05 mm.

[0014] In one embodiment, the two ends of the solder resist opening, which are arranged opposite each other along a third direction, are the third end and the fourth end, respectively, and the first direction, the second direction, and the third direction are perpendicular to each other;

[0015] If a third gap B1 is defined between the outer wall of the first pad and the third end, then: B1 = 0.05 mm;

[0016] And / or,

[0017] If a fourth gap C1 is defined between the outer wall of the first pad and the fourth end, then C1 = 0.05 mm.

[0018] In one embodiment, a fifth gap B2 is defined to be formed between the outer wall of the second pad and the third end, then: B2 = 0.05 mm;

[0019] And / or,

[0020] If a sixth gap C2 is defined between the outer wall of the second pad and the fourth end, then C2 = 0.05 mm.

[0021] In one embodiment, the length of the first pad along the second direction is defined as X, then X = 0.23 mm; the width of the first pad along the third direction is defined as Y, then Y = 0.22 mm; the first direction, the second direction, and the third direction are perpendicular to each other.

[0022] In one embodiment, the second pad is the same size as the first pad.

[0023] In one embodiment, the first pad and the second pad are symmetrically arranged with respect to the center line of the solder mask opening.

[0024] In one embodiment, the connection length between the first pad and the first shoulder along the second direction is defined as E1, then: E1≥0.1mm;

[0025] And / or,

[0026] If the connection length between the second pad and the second shoulder along the second direction is defined as E2, then E2 ≥ 0.1 mm.

[0027] In one embodiment, the first pad is electrically connected to the first solder shoulder through the first solder paste layer, and the second pad is electrically connected to the second solder shoulder through the second solder paste layer;

[0028] And / or,

[0029] The side of the first pad away from the second pad is a first arc-shaped surface, and the first arc-shaped surface extends in a direction away from the second pad;

[0030] And / or,

[0031] The side of the second pad away from the first pad is a second arc-shaped surface, which extends away from the first pad.

[0032] In one embodiment of this utility model, the surface mount component is a conventional 01005 surface mount component. A solder mask layer is disposed on the surface of the printed circuit board to prevent solder overflow and circuit oxidation. It has solder mask openings to expose the first and second pads in the underlying metal layer. By providing these openings, the soldering area is defined, and the solderability of the pads is ensured, allowing solder paste to fully wet the surfaces of both pads. Simultaneously, the areas of the first and second pads are larger than the areas of the first and second solder shoulders corresponding to the 01005 surface mount component, further increasing the contact area between the solder paste and the pads, enhancing soldering strength, avoiding cold solder joints, and thus significantly improving soldering reliability. The metal layer and solder mask layer are sequentially disposed along a first direction, forming a standard printed circuit board stack-up structure. The metal layer carries the first and second pads and the circuitry, achieving electrical connection. The first and second pads are spaced apart along a second direction to accommodate the pad spacing requirements of the 01005 surface mount component, improving mounting accuracy and soldering consistency. Furthermore, both the first and second pads are exposed through the same solder mask opening, and an appropriate spacing is provided between the two pads, thus eliminating the solder mask bridge structure between the two pads in the traditional design. This improvement fundamentally solves the common soldering defects such as solder balls, tombstoning, and cold solder joints in the SMT process of 01005 surface mount components. Specifically, regarding the solder ball problem, the spacing between the pads of 01005 surface mount components is extremely small, typically only 0.15mm to 0.2mm. If a solder mask bridge is set in the traditional structure, dead corners are easily formed at the edge of the bridge during solder paste printing, leading to solder paste accumulation. During soldering heating, the accumulated solder paste overflows due to heat and solidifies around the component to form solder balls. This utility model eliminates the solder mask bridge, and there is no physical obstruction between the first and second pads, resulting in more uniform solder paste printing. The gap between the outer wall of the first and second pads and the inner wall of the solder mask opening also provides space for the solder paste to expand, effectively reducing solder paste accumulation and overflow, thereby reducing the generation of solder balls at the source. Regarding tombstoning, 01005 surface mount components are extremely lightweight, weighing approximately 0.001g. If the first and second pads are heated unevenly, it will cause a difference in solder paste melting time. The difference in surface tension of the molten solder will pull the component towards the side that melts first, forming a tombston. The presence of traditional solder mask bridges may exacerbate the unevenness of heat conduction, as the thermal conductivity of the solder mask material is much lower than that of the substrate on the printed circuit board. If it covers the edge of a pad on one side, it will further increase the temperature difference between the two ends. This invention eliminates the solder mask bridge, making the heat conduction path of the two pads consistent with that of the substrate on the printed circuit board, resulting in more uniform heating, reducing the difference in solder paste melting time at both ends, and balancing the surface tension, thereby preventing the component from tilting and significantly reducing tombstoning.Regarding the issue of cold solder joints, the pads of 01005 surface mount components have extremely small surfaces. If the solder paste does not make sufficient contact with the pads, or if the effective soldering area is reduced due to the solder mask bridging the pads, a reliable intermetallic compound layer cannot be formed during soldering, resulting in a cold solder joint. In this invention, the first and second pads are completely exposed within the solder mask opening, with a gap between the pads and the inner wall of the solder mask opening. Furthermore, the areas of both the first and second pads are larger than the areas of the first and second solder shoulders corresponding to the 01005 surface mount component. This allows the solder paste to directly and fully cover the entire pad surface, maximizing the effective soldering area. At the same time, it avoids the restriction of solder paste flow by the edges of the solder mask bridging, ensuring that the molten solder tightly wraps around the component leads and pads, forming a uniform and reliable intermetallic compound layer, significantly improving soldering reliability. This utility model fully considers the characteristics of small pad spacing and tiny solder shoulder size of 01005 surface mount components. By eliminating the solder mask bridge between the first and second pads, and setting the first and second pads to be completely exposed within the solder mask opening, and controlling the formation of a reasonable gap between the outer walls of the first and second pads and the inner wall of the solder mask opening, it not only optimizes the solder paste printing and soldering process, but also fundamentally solves the common problems of solder balls, tombstoning, and cold solder joints in the SMT soldering process of 01005 surface mount components, improving soldering quality and product yield. It is particularly suitable for the high-precision SMT process requirements of 01005 surface mount components and has good application prospects. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of an embodiment of the solder mask opening structure for surface mount components according to the present invention.

[0035] Figure 2 This is a schematic diagram of another perspective of an embodiment of the solder mask window structure for surface mount components according to this utility model.

[0036] Figure 3 This is a schematic diagram of another embodiment of the solder resist window structure for surface mount components according to this utility model.

[0037] Explanation of icon numbers:

[0038] 100. Solder mask opening structure for surface mount components; 1. Printed circuit board; 11. Solder mask layer; 111. Solder mask opening; 1111. First end; 1112. Second end; 1113. Third end; 1114. Fourth end; 12. Metal layer; 121. First pad; 1211. First curved surface; 122. Second pad; 1221. Second curved surface;

[0039] 200, Surface mount component; 210, First solder shoulder; 220, Second solder shoulder; 310, First solder paste layer; 320, Second solder paste layer.

[0040] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0041] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0042] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, and back), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0043] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0044] With the continuous miniaturization of electronic products, 01005 surface mount components, due to their small size and high integration, are widely used in high-end electronic products, especially in EMS electronic assembly, where their application rate exceeds 95%. However, the extremely small size of 01005 surface mount components, coupled with a very narrow process window, places stringent demands on the manufacturability of the pad design. Traditional packaging designs are no longer sufficient to meet the process requirements of miniaturized components. In SMT processes, the phenomenon of "solving solder ball problems easily leading to open circuits and tombstoning" or "overcoming open circuits and tombstoning exacerbating solder ball problems" often occurs, creating a contradiction that significantly increases the soldering defect rate. The resulting high defect rate not only increases rework costs but also affects product quality and delivery cycle, causing significant losses to the SMT production line.

[0045] Solder ball defects are one of the major defects in surface mount technology (SMT), with complex causes and difficulty in control. According to the Electronic Component Acceptability Standard (IPC-A-610J), solder ball dimensions must not violate minimum electrical clearances; for 01005 surface mount components, this standard requires zero tolerance for solder balls. Solder balls typically range in diameter from 0.1mm to 0.4mm, or even larger, and are most commonly found on the sides of surface mount resistors and capacitors, and sometimes near IC or connector pins. Solder balls not only affect the product's appearance but can also detach during use, causing short circuits and seriously impacting the functionality and safety of electronic products.

[0046] The applicant's careful investigation revealed that approximately 90% of solder balls occurred on chip components, particularly 01005 surface mount components. This reflects a significant limitation in current pad designs for miniaturized components. Currently, the industry primarily uses two pad designs for 01005 surface mount components: SMD (Solder Mask Defined) and NSMD (Non-Solder Mask Defined, copper defined). Traditional designs, optimized for larger components, often result in overly large pad sizes and spacing when applied to 01005 surface mount components, making precise control of solder paste volume difficult. For example, excessively large pads can lead to excessive solder paste, causing solder balls; insufficient solder paste can result in cold solder joints. Furthermore, excessively large pad spacing increases the uncertainty of solder flow, further exacerbating soldering defects. In addition, while the larger solder mask opening in traditional designs helps reduce the risk of solder flowing to the solder mask bridge, it also increases the possibility of solder overflow. If the solder paste bridge is too wide, it may still be squeezed into non-soldered areas, leading to solder balls. Currently, reducing the stencil aperture can effectively reduce solder balls, but this may result in insufficient solder paste and cause cold solder joints.

[0047] In summary, 01005 surface mount components place higher demands on pad design, especially in products such as optical modules where miniaturization and compact PCB layout are crucial. Controlling soldering defects such as solder balls is particularly stringent, further increasing manufacturing complexity. Traditional pad designs are no longer sufficient to meet the process requirements of these components, leading to higher defect rates, more frequent rework, and severely limiting long-term product reliability and production line efficiency.

[0048] The main purpose of this invention is to propose a solder mask opening structure for surface mount components to solve the soldering defects such as solder balls, tombstoning, and cold solder joints that occur in the SMT process of 01005 surface mount components.

[0049] Please see Figure 1 and Figure 2 In one embodiment of this utility model, the solder mask opening structure 100 for surface mount components includes a printed circuit board 1, which includes a solder mask layer 11 and a metal layer 12. A solder mask opening 111 is provided on the solder mask layer 11. The metal layer 12 is connected to the solder mask layer 11, and the metal layer 12 and the solder mask layer 11 are arranged sequentially along a first direction. A first pad 121 and a second pad 122 are provided on the side of the metal layer 12 facing the solder mask layer 11. Both the first pad 121 and the second pad 122 are open to the light source. The solder mask opening 111 is exposed, and the first pad 121 and the second pad 122 are arranged at intervals along the second direction. There is a gap between the outer wall of the first pad 121 and the inner wall of the solder mask opening 111, and there is a gap between the outer wall of the second pad 122 and the inner wall of the solder mask opening 111. The first pad 121 is used for electrical connection with the first solder shoulder 210 of the surface mount component 200, and the second pad 122 is used for electrical connection with the second solder shoulder 220 of the surface mount component 200. The first direction is perpendicular to the second direction.

[0050] In one embodiment of this utility model, such as Figure 2As shown, the first direction is vertical, the second direction is horizontal, and the surface mount component 200 is a standard 01005 surface mount component. A solder mask layer 11 is disposed on the surface of the printed circuit board 1 to prevent solder overflow and circuit oxidation. It has solder mask openings 111 to expose the first pad 121 and the second pad 122 in the underlying metal layer 12. By providing the solder mask openings 111, the soldering area is defined, and the solderability of the pads is ensured, allowing the solder paste to fully wet the surfaces of the two pads. Simultaneously, the areas of the first pad 121 and the second pad 122 are both larger than the areas of the first solder shoulder 210 and the second solder shoulder 220 corresponding to the 01005 surface mount component, further increasing the contact area between the solder paste and the pads, enhancing soldering strength, avoiding cold solder joints, and thus significantly improving soldering reliability. The metal layer 12 and the solder mask layer 11 are sequentially disposed along the first direction, forming a standard printed circuit board 1 stack structure. The metal layer 12 is used to support the first pad 121, the second pad 122, and the circuitry, achieving electrical connection. The first pad 121 and the second pad 122 are arranged at intervals along the second direction to accommodate the pad spacing requirements of 01005 surface mount components, improving mounting accuracy and soldering consistency. Furthermore, both the first pad 121 and the second pad 122 are exposed through the same solder mask opening 111, and an appropriate spacing is provided between the two pads, thus eliminating the solder mask bridge structure between the two pads in traditional designs. This improvement fundamentally solves the common soldering defects of 01005 surface mount components in SMT processes, such as solder balls, tombstoning, and cold solder joints. Specifically, regarding the solder ball problem, the pad spacing of 01005 surface mount components is extremely small, typically only 0.15mm to 0.2mm. In traditional structures, if a solder mask bridge is set, dead corners are easily formed at the edges of the bridge during solder paste printing, leading to solder paste accumulation. During soldering heating, the accumulated solder paste overflows due to heat and solidifies around the component to form solder balls. This invention eliminates the solder mask bridge, eliminating physical obstruction between the first pad 121 and the second pad 122, resulting in more uniform solder paste printing. The gap between the outer walls of the first pad 121 and the second pad 122 and the inner wall of the solder mask opening 111 also provides space for the solder paste to expand, effectively reducing solder paste accumulation and overflow, thereby reducing the generation of solder balls at the source. Regarding tombstoning, the 01005 surface mount component is extremely lightweight, weighing approximately 0.001g. If the first pad 121 and the second pad 122 are heated unevenly, it will cause a difference in the melting time of the solder paste. The difference in surface tension of the molten solder will pull the component to tilt towards the side that melts first, forming a tombston. The presence of traditional solder mask bridges may exacerbate the unevenness of heat conduction, because the thermal conductivity of the solder mask material is much lower than that of the substrate on the printed circuit board 1. If it covers the edge of a pad on one side, it will further increase the temperature difference between the two ends. This utility model eliminates the solder mask bridge, making the heat conduction path of the two pads consistent with that of the substrate on the printed circuit board 1, resulting in more uniform heating, reducing the difference in the melting time of the solder paste at both ends, and balancing the surface tension, thereby preventing the component from tilting and significantly reducing the tombstoning phenomenon.Regarding the issue of cold solder joints, the pads of 01005 surface mount components have extremely small surfaces. If the solder paste does not make sufficient contact with the pads, or if the effective soldering area is reduced due to the solder mask bridging, a reliable intermetallic compound layer cannot be formed during soldering, resulting in a cold solder joint. In this invention, the first pad 121 and the second pad 122 are completely exposed within the solder mask opening 111. There is a gap between the pads and the inner wall of the solder mask opening 111, and the areas of the first pad 121 and the second pad 122 are both larger than the areas of the first solder shoulder 210 and the second solder shoulder 220 corresponding to the 01005 surface mount component. This allows the solder paste to directly and fully cover the entire pad surface, maximizing the effective soldering area. At the same time, it avoids the restriction of solder paste flow by the edge of the solder mask bridging, ensuring that the molten solder tightly wraps the component leads and the pads, forming a uniform and reliable intermetallic compound layer, significantly improving soldering reliability.

[0051] The technical solution of this utility model fully considers the characteristics of small pad spacing and tiny solder shoulder size of 01005 surface mount components. By eliminating the solder mask bridge between the first pad 121 and the second pad 122, and setting the first pad 121 and the second pad 122 to be completely exposed within the solder mask opening 111, and controlling the formation of a reasonable gap between the outer wall of the first pad 121 and the second pad 122 and the inner wall of the solder mask opening 111, it not only optimizes the solder paste printing and soldering process, but also fundamentally solves the common problems of solder balls, tombstoning, and cold solder joints in the SMT soldering process of 01005 surface mount components, improving the soldering quality and product yield. It is particularly suitable for the high-precision SMT process requirements of 01005 surface mount components and has good application prospects.

[0052] Please see Figure 1In one embodiment, the spacing between the first pad 121 and the second pad 122 is defined as G, then G = 0.16 mm. Specifically, tombstoning is usually caused by an imbalance in the wetting force of the first pad 121 and the second pad 122. Given the characteristics of 01005 surface mount components, which are very small in size, the design requirements for the pads are extremely high. Choosing a pad spacing of 0.16 mm can optimize the solder paste flow, ensuring that the solder paste can fully wet the pads, while avoiding excessive flow or overflow of solder paste. Secondly, an appropriate spacing helps the solder paste to be heated evenly during reflow soldering, reducing tombstoning caused by uneven thermal stress. Finally, a suitable spacing can effectively prevent the solder paste from overflowing between adjacent pads during melting, thereby avoiding short circuit problems. This solves common soldering defects such as tombstoning and short circuits at the root, significantly improving soldering quality and product yield, and is particularly suitable for the high-precision SMT process requirements of 01005 surface mount components. When the pad spacing is greater than 0.16mm, the larger spacing may lead to uneven heat distribution, causing the solder paste at the first pad 121 and the second pad 122 to melt and solidify at different times. This increases the complexity of solder paste flow and shrinkage, making it prone to tombstoning. In addition, a larger spacing may require more solder paste to ensure a good connection, which further increases the difficulty of solder paste flow control. Conversely, when the pad spacing is less than 0.16mm, the solder paste is more likely to overflow between adjacent pads at high temperatures, leading to short circuits. Furthermore, an excessively small spacing also means that the solder paste is more likely to be squeezed out into adjacent areas during the melting process, and may not be able to fully wet the pads, affecting the soldering quality, or even causing cold solder joints or short circuits.

[0053] Please see Figure 1In one embodiment, the solder mask opening 111 has two opposite ends arranged along the second direction, namely a first end 1111 and a second end 1112. A first pad 121 is positioned near the first end 1111, and a second pad 122 is positioned near the second end 1112. A first gap A1 is defined between the side of the first pad 121 away from the second pad 122 and the first end 1111, where A1 = 0.05 mm. And / or, a second gap A2 is defined between the side of the second pad 122 away from the first pad 121 and the second end 1112, where A2 = 0.05 mm. Specifically, the presence of the first gap A1 and the second gap A2 ensures that the solder paste has sufficient expansion space, preventing it from overflowing into non-soldered areas and thus reducing the risk of solder ball formation. Furthermore, these two gaps provide additional space for the solder paste, allowing it to distribute more evenly during melting, preventing solder paste accumulation at the pad edges, and further reducing the possibility of solder paste overflow. Furthermore, a well-designed gap helps improve the uniformity of heat conduction, reducing soldering defects such as tombstoning caused by localized temperature differences. Appropriate gaps facilitate uniform heat transfer, ensuring synchronous melting and solidification of the solder paste at both ends of the pads. Simultaneously, the design of the first gap A1 and the second gap A2 helps improve the positioning accuracy of the surface mount component 200, allowing the solder paste to more precisely cover the pad surface, thereby improving soldering quality. A well-designed gap also effectively prevents solder paste from flowing and overflowing between adjacent pads at high temperatures, thus avoiding short circuits. Finally, by optimizing the flow path and distribution of the solder paste, it is ensured that the solder paste fully wets the pad surface, forming a reliable intermetallic compound layer, thereby significantly improving soldering reliability.

[0054] Please see Figure 1 In one embodiment, the solder mask opening 111 has two opposite ends, a third end 1113 and a fourth end 1114, along a third direction, with the first direction, the second direction, and the third direction perpendicular to each other; a third gap B1 is defined to be formed between the outer wall of the first pad 121 and the third end 1113, then B1 = 0.05 mm; and / or, a fourth gap C1 is defined to be formed between the outer wall of the first pad 121 and the fourth end 1114, then C1 = 0.05 mm; specifically, as Figure 1As shown, the third direction is the front-to-back direction. The third gap B1 and the fourth gap C1 provide extended space for the solder paste around the first pad 121, effectively preventing the solder paste from overflowing into non-soldering areas due to accumulation during reflow soldering, thereby significantly reducing the risk of solder ball formation. Furthermore, the two gaps are equidistant and symmetrically arranged, which helps the solder paste to distribute evenly around the first pad 121, improving the uniformity of solder paste printing and soldering consistency. In addition, the gap size of 0.05mm is an optimized value verified through experiments. While ensuring that the solder paste fully wets the pad surface, it avoids excessively large gaps that could lead to insufficient pad exposure area or uncontrolled solder paste flow, thus achieving high-precision and high-reliability soldering results.

[0055] Please see Figure 1 In one embodiment, a fifth gap B2 is defined between the outer wall of the second pad 122 and the third end 1113, with B2 = 0.05 mm; and / or, a sixth gap C2 is defined between the outer wall of the second pad 122 and the fourth end 1114, with C2 = 0.05 mm. Specifically, the fifth gap B2 and the sixth gap C2 provide extended space for solder paste around the second pad 122, effectively preventing solder paste from overflowing into non-soldering areas due to accumulation during reflow soldering, thereby significantly reducing the risk of solder ball formation. Furthermore, the two gaps are symmetrically spaced and have the same distance, which helps the solder paste to distribute evenly around the second pad 122, improving the uniformity of solder paste printing and soldering consistency. In addition, the 0.05 mm gap size is an optimized value verified through experiments, ensuring that the solder paste fully wets the pad surface while avoiding excessively large gaps that could lead to insufficient pad exposure or uncontrolled solder paste flow, thereby achieving high-precision and high-reliability soldering results.

[0056] Please see Figure 1 In one embodiment, the length of the first pad 121 along the second direction is defined as X, then X = 0.23 mm; the width of the first pad 121 along the third direction is defined as Y, then Y = 0.22 mm; the first direction, the second direction, and the third direction are perpendicular to each other. Specifically, the length X of the first pad 121 being 0.23 mm and the width Y being 0.22 mm are optimized dimensions verified through experiments, which can adapt to the size of the first solder shoulder 210 of the 01005 surface mount component (the length and width are usually 0.1 mm × 0.2 mm), ensuring that the solder paste can fully wet the surface of the pad and improve the soldering strength. Secondly, the size of the first pad 121 is slightly larger than the size of the first solder shoulder 210, providing reasonable expansion space for the solder paste, enhancing the contact area between the first pad 121 and the solder paste, thereby effectively reducing the risk of cold solder joints and improving soldering consistency. In addition, this size design ensures the solderability of the pads while avoiding problems such as solder paste overflow or short circuits between adjacent pads caused by excessively large pads, thus improving the stability of the soldering process and product yield.

[0057] Please see Figure 1 and Figure 2 In one embodiment, the second pad 122 is the same size as the first pad 121. Specifically, the design that the first pad 121 and the second pad 122 are the same size helps to make the amount of solder paste printed on the two pads more consistent, improving solder paste wettability and melting synchronization. This consistent design also helps to achieve uniform heat conduction distribution, avoiding solder paste melting time differences caused by pad size differences, thereby effectively reducing tombstoning. In addition, the same-sized pad structure is compatible with the symmetrical shoulder structure of 01005 surface mount components, improving soldering compatibility and enhancing soldering reliability. At the same time, this design simplifies the design and manufacturing of solder paste printing stencils in the SMT process, improving production efficiency and product consistency.

[0058] Please see Figure 1 and Figure 2 In one embodiment, the first pad 121 and the second pad 122 are symmetrically arranged relative to the center line of the solder mask opening 111. Specifically, the symmetrical arrangement of the first pad 121 and the second pad 122 helps to evenly distribute the solder paste between the two pads, optimizes the solder paste flow path, and improves the wettability and melting synchronization of the solder paste during the soldering process. This symmetrical structure also helps to balance the forces on the surface mount component 200 during the soldering process, avoiding component misalignment or tilting caused by pad offset, thereby reducing the occurrence of tombstoning. In addition, this design is beneficial for the pick-and-place machine to identify and position the pads during the SMT placement process, improving placement accuracy and efficiency. At the same time, the symmetrical layout also enhances the matching between the pads and the solder shoulders of the surface mount component 200, improves soldering reliability, and reduces soldering defects such as cold solder joints and misaligned solder joints.

[0059] Please see Figure 1 In one embodiment, the connection length between the first pad 121 and the first shoulder 210 along the second direction is defined as E1, then E1 ≥ 0.1 mm; and / or, the connection length between the second pad 122 and the second shoulder 220 along the second direction is defined as E2, then E2 ≥ 0.1 mm. Specifically, by limiting E1 ≥ 0.1 mm and E2 ≥ 0.1 mm, sufficient connection length between the two pads and their corresponding shoulders is ensured, thereby effectively improving the welding connection strength and reliability. This length setting is adapted to the welding requirements of 01005 surface mount components, ensuring welding strength while avoiding problems such as cold solder joints due to excessively short connection lengths, or solder paste overflow and short circuit risks caused by excessively long connection lengths. In addition, the connection length is set along the second direction, consistent with the pad arrangement direction, adapting to the welding force direction of the surface mount component 200, further enhancing the stability of the welding structure. Combined with the design that the pad area is larger than the shoulder area, welding reliability is improved from both area and connection length dimensions, significantly improving product yield.

[0060] In this embodiment, key parameters such as the spacing G between the first pad 121 and the second pad 122, the first gap A1 and the second gap A2, the third gap B1 and the fourth gap C1, the fifth gap B2 and the sixth gap C2, the length X and width Y of the first pad 121, the connection length E1 between the first pad 121 and the first solder shoulder 210, and the connection length E2 between the second pad 122 and the second solder shoulder 220 are all systematically optimized based on the dimensional characteristics of the 01005 surface mount component and the requirements of the SMT soldering process. These parameters were verified and iteratively optimized through multiple rounds of design experiments. Combined with innovative designs of geometric structure reconstruction and solder paste distribution logic, a pad packaging solution highly adapted to the 01005 surface mount component was finally formed. This solution eliminates the traditional solder mask bridge in its structural design, optimizes the gap layout between the pad and the solder mask opening 111, and effectively controls the solder paste distribution, thereby fundamentally solving common soldering defects in the SMT process of 01005 surface mount components, such as solder balls, tombstoning, and cold solder joints. Meanwhile, this design improves welding reliability while taking into account process feasibility, achieving an organic unity of solder paste wettability, heat conduction uniformity and mounting stability, fully demonstrating the high adaptability and technological advancement of this utility model structure to 01005 surface mount components.

[0061] Please see Figure 2 In one embodiment, the first pad 121 is electrically connected to the first shoulder 210 through the first solder paste layer 310, and the second pad 122 is electrically connected to the second shoulder 220 through the second solder paste layer 320; and / or, the side of the first pad 121 away from the second pad 122 is a first arcuate surface 1211, which extends away from the second pad 122; and / or, the side of the second pad 122 away from the first pad 121 is a second arcuate surface 1221, which extends away from the first pad 121. Specifically, by clarifying that the first pad 121 and the first shoulder 210 are electrically connected through the first solder paste layer 310, and that the second pad 122 and the second shoulder 220 are electrically connected through the second solder paste layer 320, the specific implementation method of the welding structure is further clarified, enhancing the feasibility and process adaptability of the technical solution. This structure helps to clearly define the conductive paths during the soldering process, improving the reliability and consistency of solder joints. The solder paste layer, as the conductive connection medium, directly affects solder strength and electrical performance due to its quality and distribution, providing a structural basis for subsequent optimization of parameters such as solder paste thickness, area, and connection length. Furthermore, this implementation facilitates standardized operations for solder paste printing and reflow soldering control in SMT processes, improving the soldering quality and product yield of surface mount components. Please refer to [link / reference]. Figure 3In one embodiment, by setting the outer edges of the two pads to be arc-shaped and extending the arc-shaped surfaces away from the other pad, the contact area between the solder paste and the pads is increased, enhancing the wetting performance of the solder paste during the melting process, thereby effectively reducing the risk of cold solder joints. Simultaneously, this arc-shaped structure prevents the solder paste from being pulled to the outside of the pads during reflow soldering, avoiding soldering misalignment or poor connection due to solder paste loss, thus improving soldering consistency and process stability.

[0062] According to one embodiment of the present invention, the side of the first pad 121 away from the second pad 122 is a first arc-shaped surface 1211, and the first arc-shaped surface 1211 extends in a direction away from the second pad 122.

[0063] According to another embodiment of the present invention, the side of the second pad 122 away from the first pad 121 is a second arc-shaped surface 1221, and the second arc-shaped surface 1221 extends in a direction away from the first pad 121.

[0064] The above description is merely an exemplary embodiment of the present utility model and does not limit the scope of protection of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present utility model.

Claims

1. A solder resist windowing structure for a patch element, characterized by, The solder mask opening structure for surface mount components includes a printed circuit board, the printed circuit board comprising: A solder resist layer, wherein a solder resist window is provided on the solder resist layer; A metal layer is connected to the solder mask layer, and the metal layer and the solder mask layer are arranged sequentially along a first direction. A first pad and a second pad are provided on the side of the metal layer facing the solder mask layer. Both the first pad and the second pad are exposed through the solder mask opening. The first pad and the second pad are arranged at intervals along a second direction. There is a gap between the outer wall of the first pad and the inner wall of the solder mask opening, and there is a gap between the outer wall of the second pad and the inner wall of the solder mask opening. The first direction is perpendicular to the second direction. The first pad is used for electrical connection with the first solder shoulder of the surface mount component, and the area of ​​the first pad is larger than the area of ​​the first solder shoulder. The second pad is used for electrical connection with the second solder shoulder of the surface mount component, and the area of ​​the second pad is larger than the area of ​​the second solder shoulder.

2. The solder resist windowing structure for a patch element according to claim 1, wherein If the spacing between the first pad and the second pad is defined as G, then G = 0.16 mm.

3. The solder resist windowing structure for a patch element of claim 1, wherein, The solder mask opening is positioned at two opposite ends along the second direction, namely a first end and a second end, with the first pad positioned closer to the first end and the second pad positioned closer to the second end. If a first gap A1 is defined between the side of the first pad away from the second pad and the first end, then: A1 = 0.05 mm; And / or, If a second gap A2 is defined between the side of the second pad away from the first pad and the second end, then A2 = 0.05 mm.

4. The solder resist windowing structure for a patch element according to claim 3, wherein The two ends of the weld resist opening, which are respectively the third end and the fourth end, are arranged opposite each other along the third direction. The first direction, the second direction, and the third direction are perpendicular to each other. If a third gap B1 is defined between the outer wall of the first pad and the third end, then: B1 = 0.05 mm; And / or, If a fourth gap C1 is defined between the outer wall of the first pad and the fourth end, then C1 = 0.05 mm.

5. The solder resist windowing structure for a patch element of claim 4, wherein, If a fifth gap B2 is defined between the outer wall of the second pad and the third end, then: B2 = 0.05 mm; And / or, If a sixth gap C2 is defined between the outer wall of the second pad and the fourth end, then C2 = 0.05 mm.

6. The solder resist windowing structure for a patch element of claim 1, wherein, Let X be the length of the first pad along the second direction, then X = 0.23 mm; let Y be the width of the first pad along the third direction, then Y = 0.22 mm; the first direction, the second direction, and the third direction are perpendicular to each other.

7. The solder resist windowing structure for a patch element of claim 6, wherein, The second pad has the same size as the first pad.

8. The solder resist windowing structure for a patch element of claim 7, wherein, The first pad and the second pad are symmetrically arranged with respect to the center line of the solder mask opening.

9. The solder resist windowing structure for a patch element according to any one of claims 1 to 8, wherein If the connection length between the first pad and the first shoulder along the second direction is defined as E1, then: E1≥0.1mm; And / or, If the connection length between the second pad and the second shoulder along the second direction is defined as E2, then E2 ≥ 0.1 mm.

10. The solder resist windowing structure for a patch element according to any one of claims 1 to 7, wherein The first solder pad is electrically connected with the first solder shoulder through the first solder paste layer, and the second solder pad is electrically connected with the second solder shoulder through the second solder paste layer; And / or, The side of the first solder pad away from the second solder pad is a first arc surface, and the first arc surface extends away from the second solder pad; And / or, The side of the second solder pad away from the first solder pad is a second arc surface, and the second arc surface extends away from the first solder pad.

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