Pad structure and battery protection board
By providing an SSMD structure covered with air evacuation and solder resist layer at the edge of the pad, the problems of pad thickening and falling off are solved, and the stability and solder reliability of the pad are achieved.
Patent Information
- Application Number
- CN202422466595.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-12
- Publication Date
- 2025-08-29
- Estimated Expiration
- 2034-10-12
AI Technical Summary
In the existing pad design, the SMD process causes the pad to become thicker and form a monument, while the NSMD process causes the pad to form irregular and easy to fall off, resulting in poor welding and waste of R&D resources.
A new pad structure is adopted, combined with NSMD and SMD designs, and a gap is formed by setting a space evacuation at the edge of the pad and a solder resist layer covering the edge area to form an SSMD structure to avoid thickening of the solder resist bridge and enhance the firmness of the pad.
It effectively reduces the occurrence of pad monument erecting, improves the stability and solder reliability of the pads, and reduces the risk of pads falling off.
Smart Images
Figure CN223285997U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of integrated circuits, in particular to a pad structure and a battery protection board. Background Art
[0002] In the industry, pad design processes are primarily categorized as NSMD (Non-Solder Mask Defined Pad) and SMD (Solder Mask Defined Pad). Each approach offers distinct advantages and disadvantages. In SMD, pad formation is determined by the solder mask ink coating process. This process partially covers the pad, making it less likely to fall off and facilitating soldering. However, because SMD requires solder mask ink to cover copper foil, this results in thicker solder bridges, which can easily cause component tombstoning during surface mount soldering.
[0003] The NSMD process, which uses a solder mask to create pad shape, is determined by the etching process. This creates a certain gap between the solder mask and the pad, preventing overlap. This prevents the solder mask from thickening the pad. However, the pad is susceptible to corrosion during processing, resulting in irregular pad shape and a relatively high risk of pad detachment, negatively impacting soldering. To select a compatible design, the industry evaluates and verifies the process capabilities of partner component manufacturers, PCB (Printed Circuit Board) manufacturers, and SMT (Surface Mount Technology) manufacturers to determine whether to use SMD or NSMD for component pad design. This multi-source verification process wastes R&D resources and inefficiencies. Therefore, finding a pad structure that reduces tombstoning and resists detachment is a pressing challenge for those skilled in the art. Utility Model Content
[0004] The purpose of the present invention is to provide a welding pad structure, which can reduce the occurrence of tombstones and is not easy to fall off; another purpose of the present invention is to provide a battery protection plate, which can reduce the occurrence of tombstones and is not easy to fall off.
[0005] In order to solve the above technical problems, the present invention provides a pad structure, comprising at least two pads, wherein the outer side of the edge of at least one pad has a first area pointing to the adjacent pad; a solder resist bridge is formed between adjacent pads;
[0006] The first area is at least partially provided with a space-avoiding portion to form a gap between the edge of the pad and the solder resist bridge; the pad has an edge area away from the first area, the edge area and the pad are an integral structure, and the edge area is at least partially covered by the solder resist layer.
[0007] Optionally, the air-avoiding portion is arranged along the edge of the pad; and the edge area is arranged along the edge of the pad.
[0008] Optionally, the edge of the pad pointing to the side of the gap-avoiding portion is in an arc shape protruding toward the adjacent pad.
[0009] Optionally, the area where the arc is formed does not overlap with an area where the pins of the electronic component are located.
[0010] Optionally, the edge of the edge area away from the center of the pad is a right-angled edge.
[0011] Optionally, the width of the edge area is not less than 0.15 mm.
[0012] Optionally, the thickness of the solder resist bridge is smaller than the thickness of the pad.
[0013] Optionally, the difference between the thickness of the pad and the thickness of the solder resist bridge is not less than 10 μm.
[0014] Optionally, the thickness of the solder resist layer covering the edge area ranges from 10 μm to 40 μm.
[0015] Optionally, the minimum distance between the edges of adjacent pads is not less than 0.2 μm.
[0016] The present invention also provides a battery protection board, comprising an electronic component and a pad structure as described in any one of the above items, wherein the pins of the electronic component are connected to the corresponding pads.
[0017] The utility model provides a pad structure comprising at least two pads, wherein the outer side of the edge of at least one pad has a first area pointing to the adjacent pad; a solder resist bridge is formed between the adjacent pads; the first area is at least partially provided with a gap to form a gap between the edge of the pad and the solder resist bridge; the pad has an edge area away from the first area, the edge area and the pad are an integrated structure, and the edge area is at least partially covered by the solder resist layer.
[0018] By creating gaps in the first area of the pad, the thickening of solder mask bridges between adjacent pads is effectively avoided, reducing tombstone formation. The solder mask covering the pad edges prevents the pads from falling off. By combining NSMD and SMD pad structures, a new pad structure, SSMD (Semi-Solder Mask Defined Pad), is developed that prevents tombstone formation while maintaining a secure and flat pad.
[0019] The present invention also provides a circuit structure, which also has the above-mentioned beneficial effects and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0021] Figure 1 A schematic top view of a pad structure provided by an embodiment of the present utility model;
[0022] Figure 2 for Figure 1 A side structural diagram of
[0023] Figure 3 This is a schematic diagram of the structure after welding electronic components;
[0024] Figure 4 A schematic structural diagram of a specific pad structure provided in this embodiment;
[0025] Figure 5 for Figure 4 Schematic diagram of the side structure.
[0026] In the figure: 1. Solder pad, 2. Guillotine, 3. Edge area, 4. Solder resist bridge, 5. Electronic component, 6. Pin, 7. Solder flow direction. DETAILED DESCRIPTION
[0027] The core of the present invention is to provide a pad structure. In the prior art, the component pad design is selected to adopt SMD or NSMD based on the process level of the cooperating components, PCB manufacturers and SMT manufacturers through evaluation and verification.
[0028] The present invention provides a pad structure comprising at least two pads 1, wherein the outer side of the edge of at least one pad 1 has a first area pointing to the adjacent pad; a solder resist bridge 4 is formed between the adjacent pads; the first area is at least partially provided with a space-avoiding portion 2 to form a gap between the pad edge and the solder resist bridge 4; the pad 1 has an edge area 3 away from the first area, the edge area 3 and the pad 1 are an integral structure, and the edge area 3 is at least partially covered by the solder resist layer.
[0029] By providing gaps in the first area of the pad, the solder mask bridge between adjacent pads is effectively prevented from thickening, thus reducing tombstoning. The solder mask layer covers the pad edges, preventing them from falling off. By combining NSMD and SMD pad structures, a new pad structure, SSMD, is provided that prevents tombstoning while maintaining a firm and flat pad.
[0030] To help those skilled in the art better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only a portion of the present invention, not all of the embodiments. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.
[0031] Example 1
[0032] Please refer to Figures 1 to 3 , Figure 1 A schematic top view of a pad structure provided by an embodiment of the present utility model; Figure 2 for Figure 1 A side structural diagram of Figure 3 This is a schematic diagram of the structure after soldering electronic components.
[0033] See also Figure 1 as well as Figure 2 In this embodiment, the pad structure includes at least two pads 1, and the outer side of the edge of at least one of the pads 1 has a first area pointing to the adjacent pad 1; a solder resist bridge is formed between the adjacent pads 1; the first area is at least partially provided with a gap 2 to form a gap between the edge of the pad 1 and the solder resist bridge; the pad 1 has an edge area away from the first area, the edge area 3 and the pad 1 are an integral structure, and the edge area 3 is at least partially covered by the solder resist layer.
[0034] An electronic component 5 typically has two pins 6. Therefore, in this embodiment, a pad structure includes at least two pads 1, which are used to solder the electronic component 5, with each pad 1 being soldered to a corresponding pin 6. In this embodiment, each pad 1 in a set of pad structures has adjacent pads 1. Therefore, each pad 1 has a side facing the other pads 1 and a side not facing the other pads 1. Furthermore, in this embodiment, a pad 1 has a circle of areas outside its edge. In this embodiment, the area outside the edge of the pad 1 that points toward the adjacent pad 1 is referred to as the first area, and the area outside the edge of the pad 1 that does not point toward the adjacent pad 1 is referred to as the edge area. In this embodiment, a solder resist bridge 4 is formed between adjacent pads 1. The solder resist bridge 4 is also called a green oil bridge or a solder resist dam. It is an "isolation zone" used to prevent short circuits in the pins of SMD components during batch placement in the factory. That is, the solder resist bridge 4 is a solder resist layer between two adjacent pads 1, and the morphology of the solder resist bridge 4 corresponds to the window position of the pad 1 and the specific structure of the pad 1. It should be noted that in this embodiment, the surface of the pad 1 is not covered by the solder resist layer, that is, the edge of the pad 1 in this embodiment is defined by both the window position and the edge position of the conductive block serving as the pad 1. That is, the area where the conductive block and the window position overlap in the thickness direction is the pad 1.
[0035] In this embodiment, an edge region 3 is provided in a partial area outside the edge of the pad 1, and a gap 2 is provided in the first area outside the edge of the pad 1, so that the edge of the pad 1 has two different structures. The gap 2 is at least partially provided in the first area outside the edge of the pad 1. The gap 2 will form a window outside the edge of the pad 1 where no solder resist layer is present, that is, neither a solder resist layer nor a conductive block forming the pad 1 is provided in the gap 2, thereby forming a gap between the pad 1 and the solder resist bridge 4 between the adjacent pads 1 that does not include a solder resist layer and a conductive block. Obviously, the provision of the gap 2 can effectively avoid the accumulation of the thickness of the solder resist bridge 4 caused by the provision of the pad 1. The provision of the gap 2 is similar to the structure of the edge of the pad 1 in the NSMD structure.
[0036] The above-mentioned edge area 3 and the pad 1 are an integrated structure, but the difference from the pad 1 is that the edge area 3 will be at least partially covered by the solder resist layer, and usually the entire edge area 3 will be covered by the solder resist layer, thereby forming a stacked structure of the edge area 3 and the solder resist layer on the outside of the edge of the pad 1. This stacked structure can effectively prevent the pad 1 from falling off, and the setting of the stacked structure is similar to the structure of the pad edge in the SMD structure.
[0037] Typically, in this embodiment, the avoidance portion 2 is provided in the first region, along the edge of the pad 1; the edge region 3 is provided along the edge of the pad 1. Specifically, the avoidance portion 2 is provided along the entire outer edge of the pad 1, forming the first region. This prevents the solder resist bridge 4 from thickening along the edge of the pad 1 facing adjacent pads 1 due to the solder resist layer stacked on the pad 1 surface, thereby preventing the occurrence of tombstoning. The entire edge region 3 of the pad 1 is covered by the solder resist layer, forming a laminated structure, minimizing the risk of the pad 1 falling off.
[0038] It should be noted that in this embodiment, a pad 1 may have only one first region and one edge region 3, or may have multiple first regions and multiple edge regions 3. For example, when there are only two pads 1, for the pad 1 on the left, the right region of its edge is the first region pointing to the other pad 1, while the upper, right, and lower regions of the left pad 1's edge may all be provided with the aforementioned edge regions 3 that are not directed to the other pad 1. When three pads 1 are arranged in a straight line from left to right, for the pad 1 in the middle, its left and right regions may both be the first regions pointing to the adjacent pad 1, while the upper and lower regions may be provided with edge regions 3 that are not directed to the adjacent pad 1. For the four pads 1 arranged in a 2×2 pattern, taking the pad 1 in the upper left corner as an example, its right and lower regions may be the first regions pointing to the adjacent pad 1, while the left and upper regions may be provided with edge regions 3 that are not directed to the adjacent pad 1. Similarly, in this embodiment, the outer edges of the pads 1 are provided with first regions pointing to the remaining pads 1, and edge regions 3 that are not directed to the remaining pads 1.
[0039] It should be noted that the pad structure provided in this embodiment is generally suitable for small electronic components 5 with only a small number of pins 6 and a simple structure, because small electronic components 5 generally have the tombstone problem. For large electronic components with multiple pins 6, such as chips, tombstone problems generally do not exist and existing methods such as NSMD can be used for configuration. It should also be noted that the pad structure provided in this embodiment is not limited to each pad 1 being provided with the above-mentioned airtight portion 2 and edge region 3. As long as at least one pad 1 meets the above-mentioned structure, it is sufficient.
[0040] In this embodiment, the morphology of the side of the avoidance portion 2 away from the pad 1 is the same as the edge morphology of the pad 1 pointing to the avoidance portion 2, that is, the width of the above-mentioned avoidance portion 2 is usually equal everywhere; and the morphology of the side of the edge area 3 away from the pad 1 is the same as the edge morphology of the pad 1 pointing to the edge area 3, that is, the width of the above-mentioned edge area 3 is usually also equal everywhere.
[0041] Preferably, in this embodiment, the edge of the pad 1 pointing to the side of the air-avoiding portion 2 is in an arc shape protruding toward the adjacent pad 1. Since the solder will be set on the surface of the pad 1 when soldering the electronic component 5, the solder will easily spread to the edge of the pad 1 due to the extrusion of the electronic component 5 during soldering, resulting in soldering problems such as tin balls. The reason for the above-mentioned soldering problems such as tin balls is that the morphology of the edge of the pad 1 will affect the force applied to the solder during soldering, wherein the solder flow direction 7 is as shown in FIG. Figure 3 In this embodiment, the edge of the pad 1 pointing toward the air-avoidance portion 2 is configured to be arc-shaped and protrude toward the adjacent pad 1. This arc-shaped design reduces the amount of solder applied to the pad 1 in the arc-shaped area and evenly distributes the solder tension, preventing it from overflowing from the pad 1. This reduces the diffusion of solder in the arc-shaped area of the pad 1 toward the device soldering foot, thereby reducing the generation of solder balls.
[0042] The edge of the above-mentioned pad 1 pointing to the side of the avoidance portion 2 can be specifically an arc shape or any arc shape protruding toward the adjacent pad 1, and no specific limitation is made here. Correspondingly, the edge of the above-mentioned avoidance portion 2 away from the pad 1 is usually also arc-shaped, so that the gap 2 is fan-shaped as a whole.
[0043] Preferably, in this embodiment, the edge of the edge region 3 away from the center of the pad 1 is a right-angled side. Compared with a circular structure, this structure can effectively increase the area of the edge region 3, thereby increasing the area of the conductive block forming the pad 1 covered by the solder resist layer. Widening the overlapping area of the conductive block and the solder resist layer can make the pad 1 have better adhesion and not easy to fall off, while giving the electronic component 5 a larger area for the soldering feet to climb tin, and the electronic component 5 can be welded more firmly. That is, the design method of adopting a right-angled side can increase the size of the conductive block and increase the tin diffusion area so that the pin 6 of the electronic component 5 can be completely covered with tin and increase the tin adhesion. Because the surface of the edge region 3 is provided with a solder resist layer, the solder resist layer will obviously be higher than the plane where the pad 1 is located on the surface of the edge region 3, thereby forming a structure similar to a retaining wall on the edge of the pad 1 facing the edge region 3. The solder resist layer that is higher than the pad 1 can prevent the solder from flowing out of the pad 1.
[0044] For a pair of adjacent pads 1, their edge regions 3 form two sets of right-angled edges, forming a rectangular edge structure. For a 2×2 array of pads 1, their edge regions 3 typically form only one set of right-angled edges. The specific structure of these edge regions 3 can be customized based on actual conditions and is not specifically defined here. Typically, the width of these edge regions 3, meaning the area of pad 1 covered by the solder mask, is no less than 0.15mm, ensuring that pad 1 is not easily dislodged and enhancing its stability.
[0045] A pad structure provided in this embodiment can effectively avoid the thickening of the solder mask bridge between adjacent pads 1 by forming a clearance through the provision of a clearance portion 2 in the first region of the pad 1, thereby reducing the occurrence of tombstoning; while the edge region 3 of the pad 1 is covered by the solder mask layer, which can ensure that the pad 1 is not easily detached.
[0046] Specific details regarding the pad structure provided in this embodiment will be introduced in detail in the following utility model embodiments.
[0047] Embodiment Two
[0048] Please refer to Figure 4 and Figure 5 , Figure 4 which is a schematic structural diagram of a specific pad structure provided in this embodiment; Figure 5 is Figure 4 a side view structural diagram of
[0049] Different from the above utility model embodiment, this embodiment further limits the size of the pad structure on the basis of the above embodiment. The remaining content has been introduced in detail in the above utility model embodiment and will not be elaborated here.
[0050] Refer to Figure 4 and Figure 5 , in this embodiment, the thickness of the solder mask bridge 4 is less than the thickness of the pad 1. In this embodiment, the thickness of the solder mask bridge 4 is equal to the thickness of the solder mask layer. By setting the thickness of the solder mask bridge 4 to be less than the thickness of the pad 1, that is, the surface of the solder mask bridge 4 between adjacent pads 1 will not be higher than the surface of the pad 1, thereby avoiding the occurrence of tombstoning during welding. Usually, the difference between the thickness of the pad 1 and the thickness of the solder mask bridge 4 is not less than 10 μm. That is, let the thickness of the solder mask bridge 4 between the pads 1 be S1, and the thickness of the pad 1 be S2, and this thickness meets S2 - S1 > 10 μm, to prevent the problem that the electronic component 5 is lifted and ensure the adhesion of the electronic component 5 during welding.
[0051] In this embodiment, the thickness of the pad 1 includes 0.5 OZ, 1 OZ, etc., and the thickness of the pad 1 can be adjusted according to the scheme and will not be specifically limited here.
[0052] In this embodiment, the thickness value range of the solder mask layer A covering the edge region 3 is from 10 μm to 40 μm. That is, let the overlapping thickness of the solder mask layer and the pad 1 be S3, that is, the total thickness of the above-mentioned edge region 3 and the solder mask layer is S3, then it is required to meet S3 = S2 + A (10 μm < A < 40 μm), that is, the thickness value range of the solder mask layer is from 10 μm to 40 μm, including the end values.
[0053] In this embodiment, the minimum distance between the edges of adjacent pads 1 is not less than 0.2μm. To prevent bridging problems, the minimum spacing between adjacent pads 1 is set to C, and the size of C must satisfy C≥0.2um. To prevent longitudinal offset of the device and reserve space for tinning on the side of the component pins, the distance between the upper side of pin 6 and the edge of pad 1 is set to B, and the length of pin 6 is W, then B<25%×W, to prevent longitudinal offset of the device and reserve space for tinning on the side of the component pins. Usually, the distance between the lower side of pin 6 and the edge of pad 1 is also B, which also needs to satisfy B<25%×W.
[0054] In this embodiment, in order to prevent the electronic component 5 from being laterally offset and causing a cold solder joint, the distance between one pin 6 and the distal edge of the other pin 6 to be soldered is set to D, and the distance between the distal edges of the two pins 6 in the electronic component 5 is set to L. Then, it is necessary to satisfy D≤75%×L.
[0055] In this embodiment, in order to allow the pins 6 of the electronic component 5 to climb the solder to enhance adhesion, the distance between the pins 6 and the edge of the pad 1 pointing to the side of the airtight portion 2 is set to P, and the height of the pins 6 is set to H, then P≥H must be satisfied.
[0056] In this embodiment, the area where the arc is formed does not overlap with the area where the pin 6 of the electronic component 5 is located. Assuming that the area where the arc-shaped edge of the pad 1 is formed is the R area, and the area where the pin 6 is located is the Y area, then in this embodiment, the R area and the Y area do not overlap, that is, the area where the arc-shaped edge of the pad 1 is formed does not overlap with the area where the pin 6 is located, thereby ensuring that the pin 6 of the electronic component 5 has a sufficient amount of solder.
[0057] The present embodiment provides a pad structure in which the pad 1 is partially covered by a solder mask layer to ensure that the pad 1 is formed and to avoid the problem of components floating and standing upright due to the stacking and thickening of the solder mask layer and the pad 1. The pad 1 is only partially covered by a solder mask layer, so that the pad 1 is firm and not easy to fall off. The edge of the pad 1 is designed with an arc edge, so that the solder tin is gathered to the device welding foot to reduce diffusion and thus reduce the generation of tin beads. The edge of the edge area 3 is designed with a right-angle edge, and the overlapping area between the pad 1 and the solder mask layer is widened to make the pad 1 have better adhesion and not easy to fall off, while at the same time making the pin 6 of the electronic component 5 have a larger area for tin climbing, so that the electronic component 5 can be welded more firmly.
[0058] Example 3
[0059] A battery protection board provided by an embodiment of the present invention is introduced below. The battery protection board described below and the pad structure described above can be referred to each other.
[0060] In this embodiment, the battery protection board includes an electronic component 5 and a pad structure as described in any of the above embodiments. The pins 6 of the electronic component 5 are connected to the corresponding pads 1. The specific structure of the pad structure has been described in detail in the above-mentioned utility model embodiments and will not be repeated here. The specific structure of the electronic component 5 can be set according to actual conditions and will not be repeated here.
[0061] Since the battery protection board provided in this embodiment specifically uses the pad structure provided in the above embodiment, the circuit structure has higher reliability and yield rate.
[0062] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.
[0063] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.
[0064] The above is a detailed introduction to a pad structure and circuit structure provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only intended to help understand the method and core concept of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.
Claims
1. A pad structure, characterized in that: The method comprises at least two pads, wherein the outer side of the edge of at least one pad has a first area pointing to the adjacent pad; a solder resist bridge is formed between adjacent pads; The first area is at least partially provided with a space-avoiding portion to form a gap between the edge of the pad and the solder resist bridge; the pad has an edge area away from the first area, the edge area and the pad are an integral structure, and the edge area is at least partially covered by the solder resist layer.
2. The pad structure according to claim 1, wherein: The air-avoiding portion is arranged along the edge of the pad; and the edge area is arranged along the edge of the pad.
3. The pad structure according to claim 1, wherein: The edge of the pad pointing to the side of the gap-avoiding portion is in an arc shape protruding toward the adjacent pad.
4. The pad structure according to claim 3, wherein: The area where the arc is formed does not overlap with the area where the pins of the electronic component are located.
5. The pad structure according to claim 1, wherein: The edge of the edge area away from the center of the pad is a right-angled edge.
6. The pad structure according to claim 5, characterized in that: The width of the edge area is not less than 0.15 mm.
7. The pad structure according to claim 1, wherein: The thickness of the solder resist bridge is smaller than the thickness of the pad.
8. The pad structure according to claim 7, wherein: A difference between the thickness of the pad and the thickness of the solder resist bridge is not less than 10 μm.
9. The pad structure according to claim 1, wherein: The thickness of the solder resist layer covering the edge area ranges from 10 μm to 40 μm.
10. The pad structure according to claim 1, wherein: The minimum distance between the edges of adjacent pads is not less than 0.2 μm.
11. A battery protection board, characterized in that: The invention comprises an electronic component and a pad structure according to any one of claims 1 to 10, wherein the pins of the electronic component are connected to the corresponding pads.