Design method for resistance balance between printed circuit board and electroplated pad thereon

Abstract

The application provides a printed circuit board and a design method for resistance balance between electroplated PADs on the printed circuit board. Specifically, all electroplated PADs on the surface of the printed circuit board are grouped according to their areas on the surface. In any electroplated PAD group, the electroplated PAD group is connected to the first guide line adjacent to the group through the second guide line, and each electroplated PAD in the group is connected to one end of the second guide line through its corresponding branch line, so that the resistance of all electroplated PADs on the printed circuit board is the same as that of the metal frame. The application designs the branch lines of the electroplated PADs in groups and in the group, effectively realizes the resistance balance between all electroplated PADs on the printed circuit board, simplifies the mode and size of the branch line setting, improves the electroplating uniformity of all electroplated PADs on the surface of the printed circuit board, simplifies the design of the metal layer on the surface of the printed circuit board, improves the utilization rate of the surface, and saves the production cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of printed circuit board manufacturing, and more particularly, to a printed circuit board and a design method for balancing the resistance between the printed circuit board and electroplated PADs thereon. BACKGROUND

[0002] With the rapid development and wide application of integrated circuits, the types and applications of electronic devices are rapidly developing, and electronic products are becoming more intelligent and smaller. To match this, the types of printed circuit boards (PCBs) are also constantly updated, and the process requirements for printed circuit boards are becoming increasingly complex. In today's printed circuit board production and manufacturing, in order to improve the corrosion resistance, solderability and conductivity of printed circuit boards, many printed circuit boards are designed with electroplated gold technology, which is also called electroplated gold technology. Electroplated gold technology is a surface treatment technology that usually uses gold, nickel-gold alloy or gold-nickel to uniformly plate metal gold on the pads (PADs) of PCBs through electrochemical methods. The most prominent problem in the current manufacturing process is that the uniformity of electroplated gold on the printed circuit board is still not high, and the thickness of the gold plating layer produced has a large difference, with a gold thickness difference of 50% to 100%, which increases the amount of gold used and greatly increases the manufacturing cost of the printed circuit board.

[0003] The electroplated gold PADs on the PCB are important areas for electrical interconnection on the PCB, and the uniformity of the electroplated gold is crucial to its performance. In order to improve the plating uniformity of the electroplated gold PADs on the PCB, the following measures can be taken in actual production: 1. Control the current density. During the electroplating process, the current density has a great influence on the plating uniformity. Adjusting the appropriate current density can ensure the plating uniformity of the electroplated gold PADs on the PCB. 2. Optimize the composition of the electroplating solution: keeping the chemical composition in the electroplating solution, such as gold salt, cyanide, pH value, etc., within an appropriate range, helps to ensure the uniformity of the electroplated layer. 3. Adjust the process conditions: during the electroplating process, temperature, plating solution flow rate, time, etc. process conditions also affect the uniformity of the electroplated layer. 4. By using special molds and electroplating fixtures, the electroplating process of the electroplated gold PADs on the PCB can be precisely controlled. However, the above measures are essentially improvements from the manufacturing process, and do not solve the problem of electroplated gold PAD uniformity from the root cause. A method for developing and improving the uniformity of the electroplated layer on the electroplated gold PADs from the design of the printed circuit board itself is needed.

[0004] The gold finger on the PCB, such as the gold finger as the key area of the external interface on the PCB, usually needs to be frequently plugged in and out, which is easy to cause poor contact or damage due to wear. In order to improve the durability and electrical performance of the gold finger, a lead is usually arranged around the gold finger to connect to the metal frame or other metal area on the PCB, thereby enhancing the structural strength of the gold finger and reducing the influence of mechanical wear. At the same time, the lead arranged around the gold finger to connect to the metal frame can help to disperse the current load, reduce the current density, reduce the loss of the gold finger, and improve the stability and reliability of its long-term use. Further, the metal frame around the gold finger also helps to shield electromagnetic interference (EMI), especially in the PCB design of high-frequency signal transmission, which can reduce the loss and interference of the signal. When the lead is arranged around the gold finger to connect to the metal frame, the lead also needs to have sufficient electrical conductivity and sufficient mechanical strength, so that the lead can bear the current load of the area around the gold finger, avoid overheating or damage caused by excessive current, and prevent breakage caused by frequent plugging or external force. At the same time, in the actual production process, it is recommended to use a wider lead to avoid high impedance. The size and layout of the lead should be ensured not to interfere with the other functions of the gold finger area, while ensuring good electrical connection. Therefore, the layout of the lead should be avoided to be too complex, and it should be ensured that they do not affect the signal transmission layout of the PCB. Therefore, the traditional gold lead usually directly connects all the gold fingers on the PCB to the main lead through the parallelly arranged auxiliary leads, and then further connects to the metal frame. The lengths of the auxiliary leads connected by all the gold fingers are consistent, but this causes the total resistance of the gold finger connected to the main lead to be different. A new lead design method needs to be developed to make the resistance values of all the gold pads on the PCB consistent with the resistance value of the metal frame through the corresponding lead, so that the resistance values of all the gold pads to be plated on the whole board are balanced, the current distribution on the surface of the whole board is more uniform, and the metal ions in the electroplating solution can be uniformly deposited in the electroplating process, thereby improving the uniformity of the plating layer. Further, the consistent resistance values of the gold pads on the PCB surface help to maintain the stability of the current in the electroplating process, improve the electroplating efficiency, and at the same time avoid local overheating and reduce the thermal damage to the PCB surface.

[0005] Further, the resistance balancing method through lead design can be used to ensure that the resistance of each electroplated PAD on the printed circuit board is consistent with the metal frame on the board edge, and thus it is expanded to the process of electroplating nickel, gold, tin, silver, etc. on the surface of the PCB, so that all the electroplated PADs can obtain the same thickness of the required plating layer, thereby improving the uniformity of the plating layer of the electroplated PAD on the printed circuit board, improving the quality of the printed circuit board, and reducing the amount of electroplated metal, thereby saving the cost of electroplated gold, nickel, tin, silver, etc. SUMMARY

[0006] The present application aims to overcome at least one of the above-mentioned defects of the prior art, and provides a design method for balancing the resistance between electroplated PADs on a printed circuit board, which ensures that the resistance of each electroplated PAD on the printed circuit board is consistent with the metal frame along the edge of the board by balancing the design of the lead connected to the electroplated PAD, thereby improving the uniformity of electroplating on the entire printed circuit board.

[0007] The technical solution adopted by the present application is to provide a design method for balancing the resistance between electroplated PADs on a printed circuit board, the printed circuit board being provided with a conductive metal frame along the edge of the board, and the board surface of the printed circuit board being provided with a plurality of electroplated PADs, the electroplated PADs being connected to the conductive metal frame through corresponding leads, characterized in that the design method comprises the following steps:

[0008] S1. Grouping the electroplated PADs according to their positions on the printed circuit board to form a plurality of electroplated PAD groups; the electroplated PAD groups form a rectangular area, the rectangular area having a long side and a short side, and the direction of the long side being the direction in which the electroplated PADs are arranged between groups;

[0009] S2. Providing a plurality of first guide lines to separate all the electroplated PAD groups provided on the board surface, the first guide lines being provided on the board surface of the printed circuit board and connected to the conductive metal frame, so that all the electroplated PAD groups are adjacent to at least one first guide line;

[0010] S3. In any one electroplated PAD group, the electroplated PAD group is connected to the adjacent first guide line through a second guide line, and each electroplated PAD in the group is connected to one end of the second guide line through its corresponding sub-lead, so that the resistance of all the electroplated PADs on the printed circuit board and their corresponding leads is the same as the resistance of the conductive metal frame.

[0011] In the technical solution, all electroplated pads on the surface of the printed circuit board are grouped according to their areas on the surface, and the positions of the electroplated pads on the printed circuit board are grouped to form a plurality of electroplated pad groups, so as to facilitate planning the positions of the first guide lines arranged on the surface of the printed circuit board and connected to the metal frame, so that all electroplated pad groups are adjacent to at least one first guide line, so that the lead lines between the electroplated pads and the first guide lines can be designed more freely, which avoids mutual interference between adjacent electroplated pads, reduces the laying area and setting distance of the lead lines, simplifies the layout and size of the lead lines, and ensures the tolerance and reliability of the signal transmission layout on the printed circuit board. At the same time, the first guide line separates the metal frame and the adjacent electroplated pads, which can greatly reduce the edge effect on the printed circuit board and improve the electrical precision and reliability of the printed circuit board. Further, in any electroplated pad group, the electroplated pad group is connected to the first guide line adjacent thereto through the second guide line, and each electroplated pad in the group is connected to one end of the second guide line through its corresponding sub-lead line, so that the resistance of all electroplated pads on the printed circuit board is the same as that of the metal frame. The lead lines of the electroplated metal pads are designed between groups and within groups, the second guide line is arranged to connect the electroplated pad group and the first guide line adjacent thereto, and all electroplated pads in the group are connected to the second guide line and the first guide line through their corresponding sub-lead lines, so as to compress the resistance value difference of the plurality of electroplated pads in the electroplated pad group to the setting of the sub-lead line, thereby effectively realizing the resistance balance between the electroplated pads and simplifying the setting mode and size of the lead lines, thereby improving the electroplating uniformity of all electroplated pads on the surface of the printed circuit board, simplifying the metal layer design of the surface of the printed circuit board, improving the utilization rate of the surface, and saving the production cost.

[0012] Further, in any one electroplating PAD group, according to the position of the electroplating PAD in the group, the length and width of the sub-lead corresponding to the electroplating PAD are changed, so that the resistance value of each electroplating PAD to the second lead is equal, and by changing the length and width of the second lead, the resistance of all electroplating PADs in each electroplating PAD group to the conductive metal frame is the same. In the technical solution, the electroplating PAD group is connected to the first lead adjacent to it through the second lead, and all electroplating PADs in the group and their corresponding sub-lead are connected to the first lead. Since the resistance value difference of several electroplating PADs contained in the electroplating PAD group is compressed to the setting of the sub-lead corresponding to the electroplating PAD, the resistance value of the first lead in different electroplating PAD groups is determined by design due to the different positions of the electroplating PADs on the board surface, and the resistance value of each electroplating PAD in the group is also determined by design. In order to keep the resistance value of each electroplating PAD in different electroplating PAD groups consistent with the conductive metal frame, the difference between the resistance value of the first lead corresponding to the electroplating PAD group and the resistance value of the conductive metal frame is supplemented by the second lead. By changing the length and width of the second lead, the second lead can be conveniently adjusted to the required resistance value, thereby effectively realizing the resistance balance between the electroplating PADs, improving the uniformity of the electroplating PADs on the board surface, and further simplifying the mode and size of the lead setting.

[0013] Further, in any one electroplating PAD group, the sub-lead includes a first sub-lead perpendicular to the long side and corresponding to one electroplating PAD, and a second sub-lead connecting the first sub-lead and the second lead. In the technical solution, since the electroplating PAD group forms a rectangular area, in order to avoid the mutual influence between adjacent electroplating PADs, the sub-lead connecting each electroplating PAD in the group includes a first sub-lead perpendicular to the long side and corresponding to one electroplating PAD, and a second sub-lead connecting the first sub-lead and the second lead. The first sub-lead ensures the mutual isolation and independence between the electroplating PADs, and the size and position of the second sub-lead are set to design the resistance balance of the electroplating PADs in the group.

[0014] Preferably, in one embodiment of the present application, in any one electroplating PAD group, the connection point of the second guide line and the second sub-wire is arranged on the center line of the long side of the rectangular area, and one inclined second sub-wire is arranged on each side of the second guide line, and the first sub-wire corresponding to one electroplating PAD is further connected to the second sub-wire; the inclination angle and width of the second sub-wire are determined by the resistance values of the electroplating PAD located on the center line of the long side of the rectangular area and the two electroplating PADs at both ends. In this technical solution, by arranging the connection point of the second guide line and the second sub-wire on the center line of the long side of the rectangular area, and by sharing the second sub-wire by all the electroplating PADs in one electroplating PAD group, the arrangement mode between the sub-wires is simplified, interference between the second sub-wires is avoided, and manufacturing cost is further saved. Specifically, by arranging the inclined second sub-wire, the length of the first sub-wire corresponding to each electroplating PAD can be different. Since the resistance difference of the electroplating PAD itself can be compensated by the length difference of the corresponding first sub-wire and the connection length difference of the second sub-wire, the size design of all the electroplating PADs in one electroplating PAD group and their corresponding sub-wires is simplified, so that the resistance balance design of the electroplating PADs in the group is more conveniently realized under the condition of saving the setting space as much as possible; at the same time, the second sub-wire adopts the inclined wiring mode, which is smooth in transition when connected to the first sub-wire, thereby improving the stability in the signal transmission process on the printed circuit board and reducing the loss, so as to optimize the overall electrical performance of the printed circuit board.

[0015] The present technical solution also provides a printed circuit board, the printed circuit board is provided with a conductive metal frame on the edge, the conductive metal frame is arranged around a rectangular board surface without a metal layer, a plurality of electroplating PADs are arranged on the board surface, and all the electroplating PADs are connected to the conductive metal frame through a lead group, the lead group is arranged according to the design method for balancing the resistance between the electroplating PADs on the printed circuit board provided in the present technical solution, and the resistance of all the electroplating PADs on the printed circuit board is the same as the resistance of the conductive metal frame. By adjusting the lead group corresponding to the electroplating PAD, the resistance of all the electroplating PADs on the printed circuit board is the same as the resistance of the conductive metal frame, so that the current can be uniformly distributed on the entire surface of the printed circuit board during the electroplating process, and the uniformity of the electroplating of all the electroplating PADs on the printed circuit board is improved.

[0016] Further, all the electroplating PADs are grouped into a plurality of electroplating PAD groups according to the positions of the electroplating PADs arranged on the printed circuit board, and the lead group includes a first guide line and a second guide line for connecting the electroplating PAD group and the conductive metal frame, and a sub-wire for connecting all the electroplating PADs in the electroplating PAD group;

[0017] The long side and the short side of the rectangular area formed by the electroplating PAD group are parallel to the edge line of the board surface.

[0018] The first guide line connects the opposite two sides of the metal frame and divides the board surface area of the printed circuit board in a manner parallel to the edge line of the board surface.

[0019] In the technical solution, by designing the rectangular area formed by the electroplating PAD group to be parallel to the rectangular board surface of the printed circuit board, and all the electroplating PAD groups on the board surface to be adjacent to at least one first guide line, and by designing the first guide line to connect the opposite two sides of the metal frame and divide the board surface area of the printed circuit board in a manner parallel to the edge line of the board surface, the direct connection between the electroplating PAD and the metal frame is avoided, the edge effect of the surface of the printed circuit board is reduced, the layout of the electroplating PAD and the first guide line is facilitated, the wiring mode and the wiring amount on the printed circuit board are simplified, the utilization rate of the board surface is improved, and the manufacturing cost is saved. Further, by arranging the second guide line to further connect the electroplating PAD groups and the first guide line, the resistance difference between the electroplating PAD groups and the first guide line in different areas of the board surface is flexibly adjusted by adjusting the size and arrangement mode of the second guide line, and the resistance balance between the groups is achieved. Meanwhile, in any electroplating PAD group, the resistance difference between the electroplating PADs in the same group is flexibly adjusted by adjusting the size and arrangement mode of the sub-wires arranged corresponding to each electroplating PAD, and the resistance balance in the group is achieved. By such arrangement, the resistance balance between the electroplating PADs is effectively achieved, the wiring arrangement mode and size are simplified, the utilization rate of the board surface is improved, and the manufacturing cost is saved.

[0020] Preferably, in order to improve the independence of the arrangement of the electroplating PAD, avoid the interference between the wires, further simplify the wiring arrangement mode on the printed circuit board, improve the utilization rate of the board surface, and in any electroplating PAD group, the connection point of the second guide line and the sub-wire is located on the center line of the long side of the rectangular area, the sub-wire includes a first sub-wire arranged perpendicularly to the long side and a second sub-wire arranged obliquely, and the resistance values of the sub-wires corresponding to each electroplating PAD are equal.

[0021] Further, the second guide line includes a plurality of vertical guide lines and a plurality of horizontal guide lines connected to each other, the vertical guide lines are parallel to the first sub-wire, and the horizontal guide lines are arranged parallel to the long side of the rectangular area; the second guide line is connected to the sub-wire, the first guide line and the metal frame through the vertical guide lines.

[0022] In the technical solution, in order to keep the resistance values of the electroplated pads in different electroplated pad groups consistent with the conductive metal frame, the differences between the electroplated pad groups due to the corresponding first guide lines and the resistance values of the electroplated pad groups and the conductive metal frame are compensated by the second guide lines, the second guide lines can be conveniently adjusted to the required resistance values by changing the setting length and width of the second guide lines, in order to reduce the wiring size of the lead groups on the printed circuit board and improve the utilization rate of the board surface, the second guide lines can adopt the bending lead, specifically, including a plurality of vertical guide lines and a plurality of horizontal guide lines connected with each other, the vertical guide lines are parallel to the first sub-lead, the horizontal guide lines are arranged parallel to the long side of the rectangular area, and the second guide lines are connected with the sub-lead, the first guide line and the conductive metal frame through the vertical guide lines, so that the overall setting length of the second guide lines is as long as possible in the limited plane space size, thereby effectively realizing the resistance balance between the electroplated pads, improving the uniformity of the electroplated pads on the board surface, and further simplifying the mode and size of the lead setting. Preferably, the line gap between the horizontal guide lines is not less than 30 μm, which reduces the requirement for the manufacturing process of the line and ensures the fineness of the overall manufacturing of the second guide lines.

[0023] Preferably, the metal plating layer on the electroplated pad is one or more of gold, silver, nickel, tin and copper, and the sub-lead, the first guide line and the second guide line all adopt copper.

[0024] Preferably, the thickness of the metal plating layer on the electroplated pad is not less than 0.01 μm.

[0025] Compared with the prior art, the beneficial effects of the present application are:

[0026] 1. By grouping all the electroplated pads on the surface of the printed circuit board according to their regions on the board surface, the positions of the electroplated pads on the printed circuit board are used to group the electroplated pads to form a plurality of electroplated pad groups, thereby facilitating the planning of the positions of the first guide lines on the surface of the printed circuit board and connecting the conductive metal frame, so that all the electroplated pad groups are adjacent to at least one first guide line, thereby more freely designing the leads between the electroplated pads and the first guide lines, avoiding the mutual interference of the leads between the adjacent electroplated pads, reducing the laying area and setting distance of the leads, simplifying the layout and size of the leads, and ensuring the tolerance and reliability of the signal transmission layout on the printed circuit board; at the same time, the first guide line separates the conductive metal frame and the adjacent electroplated pads, greatly reducing the edge effect on the printed circuit board and improving the electrical precision and reliability of the printed circuit board.

[0027] 2、In any one electroplating PAD group, the electroplating PAD group is connected to the first guide line adjacent to it through the second guide line, and each electroplating PAD in the group is connected to one end of the second guide line through its corresponding branch line, so that the resistance of all electroplating PADs on the printed circuit board is the same as that of the conductive metal frame, the lead of the electroplating metal PAD is designed in groups and within the group, the second guide line is arranged to connect the electroplating PAD group and the first guide line adjacent to it, and all electroplating PADs in the group are connected to the first guide line through their corresponding branch lines, so that the resistance value difference of several electroplating PADs contained in the electroplating PAD group is compressed to the setting of the branch line, thereby effectively realizing the resistance balance between the electroplating PADs and simplifying the mode and size of the lead setting, thereby improving the plating uniformity of all electroplating PADs on the surface of the printed circuit board, simplifying the metal layer design of the printed circuit board surface, improving the utilization rate of the surface, and saving the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flowchart of the design method for balancing the resistance between the electroplating PADs on the printed circuit board provided by the present application.

[0029] Figure 2 The structure diagram of the printed circuit board provided by the present application.

[0030] Figure 3 The structure diagram of the electroplating PAD group and the lead group on the printed circuit board provided by the present application.

[0031] Figure 4 The structure diagram of the electroplating PAD group and the lead group on the printed circuit board provided by Example 3.

[0032] Figure 5 The structure diagram of the electroplating PAD group and the traditional lead group on the printed circuit board provided by Comparative Example 1.

[0033] BRIEF DESCRIPTION OF DRAWINGS: conductive metal frame 10, surface 20, electroplating PAD group 30, lead group 40, electroplating PAD 100, first guide line 210, second guide line 220, first branch line 230, and second branch line 240. DETAILED DESCRIPTION

[0034] The drawings of the present application are only used for illustrative explanation, and cannot be understood as a limitation of the present application. In order to better illustrate the following examples, some components in the drawings may be omitted, enlarged or reduced, and do not represent the actual size of the product; it is understandable for those skilled in the art that some known structures and their descriptions in the drawings may be omitted.

[0035] Example 1

[0036] AsFigures 1-2 The embodiment shown provides a design method for balancing the resistance between electroplated PADs 100 on a printed circuit board. The printed circuit board is provided with a conductive metal frame 10 along the edge of the board. The printed circuit board is provided with a plurality of electroplated PADs 100 on the board surface 20. The electroplated PADs 100 are connected to the conductive metal frame through corresponding lead wires. The design method comprises the following steps:

[0037] S1. Group the electroplated PADs 100 according to their positions on the printed circuit board to form a plurality of electroplated PAD groups 30. The electroplated PAD groups 30 form a rectangular area with a long side and a short side. The long side is in the direction of the arrangement of the electroplated PADs 100 between groups.

[0038] S2. Provide a plurality of first guide lines 210 to separate all the electroplated PAD groups 30 on the board surface 20. The first guide lines 210 are provided on the board surface 20 of the printed circuit board and connected to the conductive metal frame 10, so that all the electroplated PAD groups 30 are adjacent to at least one first guide line 210.

[0039] S3. In any one electroplated PAD group 30, the electroplated PAD group 30 is connected to the adjacent first guide line 210 through a second guide line 220. Each electroplated PAD 100 in the group is connected to one end of the second guide line 220 through a corresponding branch lead wire, so that the resistance of all the electroplated PADs 100 on the printed circuit board and their corresponding lead wires is the same as the resistance of the conductive metal frame 10.

[0040] Specifically, the electroplated metal PADs on the printed circuit board are designed with group-to-group lead wires through grouping and the provision of first guide lines 210 and second guide lines 220. The group-to-group design is further achieved through branch lead wires connected to the electroplated PADs 100. The resistance values of all the electroplated PADs 100 on the printed circuit board and the conductive metal frame 10 are adjusted to be the same, effectively balancing the resistance between all the electroplated PADs 100 on the printed circuit board while simplifying the lead wire setting method and size. The electroplating uniformity of all the electroplated PADs 100 on the surface of the printed circuit board is improved, the metal layer design of the board surface 20 of the printed circuit board is simplified, the board surface utilization is improved, and the production cost is saved.

[0041] Further, in any one electroplating PAD group 30, according to the position of the electroplating PAD 100 in the group, the length and width of the corresponding sub-lead of the electroplating PAD 100 are changed, so that the resistance value of each electroplating PAD 100 to the second lead 220 is equal, and by changing the length and width of the second lead 220, the resistance of all electroplating PADs 100 in each electroplating PAD group 30 to the conductive metal frame 10 is the same. In the present technical solution, the electroplating PAD group 30 is connected to the first lead 210 adjacent to it through the second lead 220, and all electroplating PADs 100 in the group and their corresponding sub-lead are connected to the first lead 210. Since the resistance value difference of several electroplating PADs 100 contained in the electroplating PAD group 30 is compressed to the setting of the sub-lead corresponding to the electroplating PAD 100, the resistance value of each electroplating PAD 100 in the group is designed to be determined due to the length and resistance value of the first lead 210 in different areas of the board 20, and the resistance value of each electroplating PAD 100 in the group is designed to be determined. In order to keep the resistance value of each electroplating PAD 100 in different electroplating PAD groups 30 consistent with the conductive metal frame 10, the difference between the resistance value of the first lead 210 corresponding to each electroplating PAD group 30 and the resistance value of the conductive metal frame 10 is supplemented by the second lead 220. By changing the length and width of the second lead 220, the second lead 220 can be conveniently adjusted to the required resistance value, thereby effectively realizing the resistance balance between the electroplating PADs 100, improving the uniformity of the electroplating PADs 100 on the board 20, and further simplifying the mode and size of the lead setting.

[0042] Further, in any one electroplating PAD group 30, the sub-lead includes a first sub-lead 230 perpendicular to the long side and corresponding to one electroplating PAD 100, and a second sub-lead 240 connecting the first sub-lead 230 and the second lead 220. In the present technical solution, since the electroplating PAD group 30 forms a rectangular area, in order to avoid mutual influence between adjacent electroplating PADs 100, the sub-lead connecting each electroplating PAD 100 in the group includes a first sub-lead 230 perpendicular to the long side and corresponding to one electroplating PAD 100, and a second sub-lead 240 connecting the first sub-lead 230 and the second lead 220. The first sub-lead 230 ensures the mutual isolation and independence between the electroplating PADs 100, and the size and position of the second sub-lead 240 are set to design the resistance balance of the electroplating PADs 100 in the group.

[0043] Preferably, in any electroplated PAD group 30, the connection point between the second guide line 220 and the second branch line 240 is located on the center line of the long side of the rectangular area. An inclined second branch line 240 is provided on each side of the second guide line 220. The first branch line 230 is connected to an electroplated PAD 100 and further connected to the second branch line 240. The inclination angle and width of the second branch line 240 are determined by the resistance values ​​of the electroplated PAD 100 located on the center line of the long side of the rectangular area and the two electroplated PAD 100s at both ends. By setting the connection point between the second guide line 220 and the second branch line 240 on the center line of the long side of the rectangular area, and by having all electroplated PADs 100 in one electroplated PAD group 30 share the second branch line 240, the arrangement of the branch lines is simplified, interference between the second branch lines 240 is avoided, and manufacturing costs are further reduced. Specifically, by setting the inclined second branch line 240, the length of the first branch line 230 connected to each electroplated PAD 100 can be different. Since the resistance difference of the electroplated PAD 100 itself can be compensated by the difference in the length of the corresponding first branch line 230 and the connection length of the second branch line 240, the size design of all electroplated PAD 100 and their corresponding branch lines in an electroplated PAD group 30 is simplified. This allows for a more convenient design of resistance balance of the electroplated PAD 100 in the group while saving as much space as possible. At the same time, the inclined routing of the second branch line 240 makes the transition when connecting the first branch line 230 smoother, thereby improving the stability of signal transmission on the printed circuit board, reducing losses, and thus optimizing the overall electrical performance of the printed circuit board.

[0044] Example 2

[0045] like Figures 2-3 As shown, this embodiment provides a printed circuit board (PCB). A conductive metal frame 10 is provided along the edge of the PCB, surrounding a rectangular surface 20 without a metal layer. A plurality of electroplated pads 100 are disposed on the surface 20, and all electroplated pads 100 are connected to the conductive metal frame 10 via lead groups 40. The lead groups 40 are configured according to the resistance balancing design method for the electroplated pads 100 on the PCB provided in this technical solution, ensuring that the resistance of all electroplated pads 100 on the PCB is the same as the resistance of the conductive metal frame 10. By adjusting the lead groups 40 connected to the electroplated pads 100, the resistance of all electroplated pads 100 on the PCB is made the same as the resistance of the conductive metal frame 10, thereby ensuring that the current is evenly distributed across the entire surface of the PCB during the electroplating process, improving the uniformity of electroplating of all electroplated pads 100 on the PCB.

[0046] Further, all the electroplated Pads 100 are grouped to form several electroplated Pad groups 30 according to the positions of the electroplated Pads 100 on the printed circuit board, the lead group 40 includes the first lead line 210 and the second lead line 220 for connecting the electroplated Pad groups 30 and the conductive metal frame 10, and the sub-lead lines for connecting all the electroplated Pads 100 in the electroplated Pad groups 30; the long side and the short side of the rectangular area formed by the electroplated Pad groups 30 are parallel to the edges of the board surface 20; the first lead line 210 connects the opposite edges of the conductive metal frame 10 and divides the area of the board surface 20 of the printed circuit board in a manner parallel to the edges of the board surface 20. By connecting the electroplated Pad groups 30 and the first lead line 210, the direct connection between the electroplated Pads 100 and the conductive metal frame is avoided, the edge effect of the surface of the printed circuit board is reduced, and the wiring mode and wiring on the printed circuit board are simplified. Further, by connecting the electroplated Pad groups 30 and the first lead line 210 through the second lead line 220, the resistance difference between the electroplated Pad groups 30 and the first lead line 210 in different areas of the board surface 20 can be flexibly adjusted by adjusting the size and setting mode of the second lead line 220, so as to realize the resistance balance between the groups; at the same time, in any one of the electroplated Pad groups 30, the resistance difference between the electroplated Pads 100 in the same group can be flexibly adjusted by adjusting the size and setting mode of the sub-lead line corresponding to each electroplated Pad 100, so as to realize the resistance balance in the group; by such a setting, the resistance balance between the electroplated Pads 100 is effectively realized, the wiring setting mode and size are simplified, the board surface utilization is improved, and the production cost is saved.

[0047] Preferably, in order to improve the setting independence of the electroplated Pads 100, avoid the setting interference between the lead lines, further simplify the setting mode of the lead lines on the printed circuit board, and improve the board surface 20 utilization, in any one of the electroplated Pad groups 30, the connection point of the second lead line 220 and the sub-lead line is located on the center line of the long side in the rectangular area, the sub-lead line includes the first sub-lead line 230 perpendicular to the long side and the second sub-lead line 240 obliquely arranged, and the resistance values of the sub-lead lines corresponding to each electroplated Pad 100 are equal.

[0048] Furthermore, to ensure that the resistance of each plated PAD 100 within different plated PAD groups 30 is consistent with that of the conductive metal frame 10, the differences between each plated PAD group 30 caused by the corresponding connected first guide line 210 and the resistance of the plated PAD group 30 itself compared with the resistance of the conductive metal frame 10 are compensated by the second guide line 220. The resistance of the second guide line 220 can be easily adjusted to the required value by changing its length and width. To reduce the wiring size of the lead group 40 on the printed circuit board and improve the utilization rate of the board surface 20, the second guide line 220 can be a bent lead. Specifically, it includes several interconnected vertical guide lines and several horizontal guide lines. The vertical guide lines are parallel to the first branch lead 230, and the horizontal guide lines are parallel to the long side of the rectangular area. The second guide line 220 is connected to the branch lead, the first guide line 210, and the conductive metal frame 10 via the vertical guide lines. This maximizes the overall length of the second guide line 220 within a limited planar space, effectively achieving resistance balance among the electroplated PADs 100 and improving the uniformity of electroplating on the board surface 20, while further simplifying the lead setting method and size. Preferably, the gap between the horizontal guide lines is not less than 300μm, reducing the requirements for the circuit manufacturing process and ensuring the overall precision of the second guide line 220.

[0049] Preferably, the metal plating on the electroplated PAD100 is one or more of gold, silver, nickel, tin, and copper, and the lead wire, the first lead wire 210 and the second lead wire 220 are all made of copper.

[0050] Preferably, the thickness of the metal plating on the electroplated PAD100 is not less than 0.010 μm.

[0051] Example 3

[0052] like Figure 3 As shown, this embodiment also provides a printed circuit board. The difference from embodiment 2 is that, for the lead groups connected to the electroplated PADs, in any electroplated PAD group, the connection point between the second guide line and the branch lead is located on the center line of the long side of the rectangular area. The branch lead includes a first branch lead perpendicular to the long side and a second branch lead inclined thereon. An inclined second branch lead is provided on each side of the second guide line. The first branch lead is connected to an electroplated PAD and further connected to the second branch lead. The inclination angle and width of the second branch lead are determined by the resistance values ​​of the electroplated PAD located on the center line of the long side of the rectangular area and the two electroplated PADs at both ends.

[0053] Specifically, for this lead group, by changing the connection method between the electroplated PAD and the second guide line, the resistance value of each electroplated PAD in the group to the second guide line can be made equal, thus achieving resistance balance within the electroplated PAD group. The calculation method is as follows:

[0054] like Figure 4 As shown, A1 is the first guide line, L2 is the length of the second branch line, L1 is the length of the first branch line connecting the non-edge electroplated PAD in the group that is longer than L3, L3 is the length of the first branch line between the edge electroplated PAD in the group and the second guide line, T1 is the second guide line, T2 is the second branch line, T3 is the first branch line, T4 is the electroplated PAD, W1 is the width of the first branch line, and W2 is the width of the second branch line.

[0055] The formula for calculating resistance is:

[0056] R = ρL / S = ρL / WH (Equation 1)

[0057] For a given printed circuit board, the width W1 of the first lead T3 is a constant, the copper thickness H is a constant, the angle θ of the second lead is a constant, and the gap X between adjacent plated pads is a constant. Therefore, starting from the middle plated pad, for each plated pad moved to the left or right, the length of L1 decreases by one unit, and the length of L2 increases by one unit. By calculating and adjusting the width W2 of the inclined conductive line using the following formula, the decrease in resistance of L1 equals the increase in resistance of L2, thus achieving equal resistance from each finger to the conductive point.

[0058] R L1减 =R L2增 =ρL 1减 / W1*h =ρL 2增 / W2*h, that is, W2=W1*L 2增 / L 1减 (Equation 2)

[0059] sinθ=L 1减 / L 2增 That is, L 2增 / L 1减 =1 / sinθ (Formula 3)

[0060] Substituting Equation 3 into Equation 2, we can obtain W2 = W1 / sinθ. Both angle θ and W1 are constants. Combining this with Equation 1, we can calculate the width of W2, thus ensuring that the resistance of each electroplated PAD in the group to the second guide line is equal.

[0061] Example 4

[0062] like Figure 4The embodiment is a verification process of the resistance equalization effect between the electroplated PADs after the lead group is used on a printed circuit board provided in Example 3, and is specifically as follows:

[0063] According to the product design information, it is known that the electroplated PAD is a gold finger, the plating layer is gold, the lead group is made of metal copper, and the copper thickness is equal, H=0.055 mm. According to the product information, the length of L1 is measured to be 6 mm, the length of the second sub-lead L2 is 41 mm, and X=8.1 mm. According to the internal design rules, the width W1 of L1 can be determined to be 0.2 mm.

[0064] 1. The electroplated PADs in the electroplated PAD group are balanced and adjusted:

[0065] According to the known conditions, R L1 (ρ-the resistivity of copper at room temperature: 0.0175 mOhm*mm) can be calculated:

[0066] R L1 =ρL1 / H*W1=0.0175 mOhm*mm*6 mm / 0.055 mm*0.2 mm=9.5 mOhm

[0067] In order to make R L1 =R L2 , W2 can be directly calculated according to the resistance by using the formula:

[0068] W2=ρL2 / H* R L2 =0.0175 mOhm*mm*41 mm / 0.055 mm*9.5 mOhm=1.37 mm

[0069] That is, the adjustment width of W2 is 1.37 mm.

[0070] 2. The calculation results above are matched and verified with the results calculated by combining the product information with the theoretical formula:

[0071] According to the known product rule information, the inclination angle θ of the second sub-lead can be calculated to be approximately 8.33°

[0072] W2=W1 / sinθ=0.2 mm / sin(8.33°)=1.38 mm, which is consistent.

[0073] 3. Whether the change amount of the first lead between the adjacent electroplated PADs in the group is consistent with the change amount of the second sub-lead:

[0074] Given the angle θ and W2, R L2增 and R L1减 can be calculated:

[0075] L 1减=tanθ*X=0.146*8.1=1.19mm;

[0076] L 2增 =L1 / sinθ=1.19 / 0.828=8.21mm;

[0077] R L1减 =ρ*L 1减 / W1*H=(0.0175*1.19) / (0.2*0.055)=1.89mohm;

[0078] R L2增 =ρ*L 2增 / W2*H=(0.0175*8.21) / (1.37*0.055)=1.90mohm;

[0079] The calculation results show that R L2增 Equal to RL 1减 .

[0080] 4. Verify whether the resistance from each plated PAD in the group to the first guide wire is the same:

[0081] like Figure 4 As shown, each electroplated PAD is numbered starting from the middle, and from the center outwards, they are numbered 1, 2, 3, 4, 5, 6. The point where the entire group of d-plated PADs is connected to the main lead is marked as point o. Calculate and optimize the resistance of each electroplated PAD from point o.

[0082] R L3 =ρ*L3 / W1*H=(0.0175*2) / (0.2*0.055)=3.18mohm

[0083] The resistance of the first and second leads connecting the electroplated PADs in the group is consistent for the entire group of electroplated PADs. Substituting the actual design data into the calculation, we can obtain:

[0084] R T1 =ρ*L T1 / W T1 *H=(0.0175*84) / (0.5*0.055)=53.45mohm;

[0085] The resistance value from each electroplated PAD to point O is calculated as follows:

[0086] R1=R L3 +R L1 +R T1 ;

[0087] R2=R L3 +R L1 -1*R L1减 +1*RL2增 +R T1 ;

[0088] R3= R L3 +R L1 -2*R L1减 +2*R L2增 +R T1 ;

[0089] R4= R L3 +R L1 -3*R L1减 +3*R L2增 +R T1 ;

[0090] R5= R L3 +R L1 -4*R L1减 +4*R L2增 +R T1 ;

[0091] R6= R L3 +R L1 -5*R L1减 +5*R L2增 +R T1 ;

[0092] Substitute the data to calculate the final result R1=R2=R4=R5=R6=66.13mohm.

[0093] Therefore, when the lead group is used, it can be ensured that each electroplated PAD in each electroplated PAD group on the printed circuit board maintains resistance balance.

[0094] Comparative Example 1

[0095] In this comparative example, a printed circuit board is also provided, which is different from Examples 3 and 4 in that the electroplated PADs on the printed circuit board are connected to the through metal frame by the traditional lead group as shown in Figure 5 Specifically, the electroplated PADs are connected to the main lead (equivalent to the first lead in the present application) through the equal-length auxiliary lead.

[0096] The printed circuit board provided in this comparative example and the printed circuit board provided in Example 3 are subjected to electroplating processes according to the same process parameters, so that all the electroplated PADs on the printed circuit board are covered with a gold plating layer. The thickness of the gold plating layer on the two printed circuit boards is collected and analyzed for thickness uniformity of the gold plating layer in the group and the whole board, and the following table is obtained:

[0097]

[0098] It can be seen that, compared with the printed circuit board provided in Comparative Example 1, when the lead group is connected to the electroplated PAD on the printed circuit board provided in Example 3, the average plating layer thickness of the electroplated PAD on the printed circuit board increases and is closer to the preset plating layer thickness, indicating that the electroplating efficiency in the electroplating process increases; at the same time, the variance of the plating layer thickness of all the electroplated PADs on the whole printed circuit board is small, and the range of each electroplated PAD group on the board surface is reduced as a whole, indicating that the difference in the plating layer thickness of all the electroplated PADs on the printed circuit board is small, that is, the electroplating uniformity of all the electroplated PADs on the printed circuit board is greatly improved.

[0099] Obviously, the above examples of the present application are only examples for clearly illustrating the technical solutions of the present application, and are not intended to limit the specific embodiments of the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the claims of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A design method for resistance balancing between electroplated PADs on a printed circuit board, wherein a conductive metal frame is provided along the edge of the printed circuit board, and a plurality of electroplated PADs are provided on the surface of the printed circuit board, wherein the electroplated PADs are connected to the conductive metal frame through corresponding leads, characterized in that... The design method includes the following steps: S1. Based on the position of the electroplated PAD on the printed circuit board, the electroplated PADs are grouped to form several electroplated PAD groups; each electroplated PAD group forms a rectangular area, which has a long side and a short side, with the direction in which the electroplated PADs are arranged in the group being the direction of the long side. S2. Set a number of first guide lines to separate all electroplated PAD groups on the board surface. The first guide lines are set on the board surface of the printed circuit board and connected to the conductive metal frame, so that all electroplated PAD groups are adjacent to at least one first guide line. S3. In any group of electroplated PADs, the group of electroplated PADs is connected to the first guide line adjacent to it through the second guide line, and each electroplated PAD in the group is connected to one end of the second guide line through its corresponding branch line, so that the resistance from all electroplated PADs on the printed circuit board to the conductive metal frame is the same. In any group of electroplated PADs, the length and width of the corresponding lead wires of the electroplated PADs are changed according to their positions in the group, so that the resistance value of each electroplated PAD to the second lead wire is equal. Furthermore, by changing the setting length and width of the second lead wire, the resistance of all electroplated PADs in each group to the conductive metal frame is the same.

2. The design method according to claim 1, characterized in that, In any group of electroplated PADs, the branch leads include a first branch lead perpendicular to the long side and correspondingly connected to an electroplated PAD, and a second branch lead connecting the first branch lead and the second guide line.

3. The design method according to claim 2, characterized in that, In any electroplated PAD group, the connection point of the second guide line and the second branch line is set on the center line of the long side of the rectangular area. An inclined second branch line is provided on both sides of the second guide line. The first branch line is connected to an electroplated PAD and further connected to the second branch line. The tilt angle and width of the second lead are determined by the resistance values ​​of the electroplated PAD located on the center line of the long side of the rectangular area and the two electroplated PADs at both ends.

4. A printed circuit board, wherein a conductive metal frame is provided along the edge of the printed circuit board, the conductive metal frame surrounds a rectangular surface without a metal layer, and a plurality of electroplated pads are provided on the surface of the board, and all electroplated pads are connected to the conductive metal frame via lead groups, characterized in that, The lead group is configured according to the resistance balancing design method between electroplated PADs on the printed circuit board as described in any one of claims 1-3, so that the resistance from all electroplated PADs to the conductive metal frame on the printed circuit board is the same.

5. The printed circuit board according to claim 4, characterized in that, Based on the position of the electroplated PADs on the printed circuit board, all electroplated PADs are grouped into several electroplated PAD groups. The lead group includes a first guide line and a second guide line for connecting the electroplated PAD group and the conductive metal frame, as well as branch leads for connecting all electroplated PADs in the electroplated PAD group. The long and short sides of the rectangular area formed by the electroplated PAD group are both parallel to the edge lines of the plate surface; The first guide line connects two opposite sides of the conductive metal frame and divides the printed circuit board area in a manner parallel to the edge line of the board surface.

6. The printed circuit board according to claim 5, characterized in that, In any electroplated PAD group, the connection point between the second guide line and the branch lead is located on the center line of the long side of the rectangular area. The branch lead includes a first branch lead set perpendicular to the long side and a second branch lead set at an angle. The resistance values ​​of the branch leads connected to each electroplated PAD are equal.

7. The printed circuit board according to claim 6, characterized in that, The second guide line includes several interconnected vertical guide lines and several horizontal guide lines. The vertical guide lines are parallel to the first branch guide line, and the horizontal guide lines are parallel to the long side of the rectangular area. The second guide line is connected to the branch guide line and the first guide line through the vertical guide lines.

8. The printed circuit board according to any one of claims 4-7, characterized in that, The metal plating on the electroplated PAD is one or more of gold, silver, nickel, tin, and copper, and the branch leads, the first guide line, and the second guide line are all made of copper.

9. The printed circuit board according to claim 8, characterized in that, The thickness of the metal plating on the electroplated PAD is not less than 0.01 μm.

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