Manufacturing method for gold-plated finger of circuit board and circuit board

Abstract

The invention relates to a method for manufacturing a gold-plated finger of a circuit board and the circuit board, and the method comprises the following steps: S1, manufacturing an outer layer pattern of the circuit board: manufacturing a golden finger region while manufacturing an outer layer circuit pattern; the golden finger area comprises a golden finger pattern, a copper exposing area, a first lead led out from the copper exposing area and a second lead led out from the middle of the golden finger pattern, and the width of the second lead is larger than that of the first lead; s2, resistance welding: coating a non-golden finger area of the circuit board with resistance welding ink; s3, gold finger plating: clamping two gold plating clamps at different positions of the copper exposure area, and loading current to the two gold plating clamps; and S4, periphery forming: milling off the base material and the copper exposing area at the periphery of the circuit board, and part of the first lead and the second lead. By arranging the first lead and the wider second lead, two sections of current paths are created, so that the golden finger is protected, and the integrity and the processing safety of the golden finger are ensured.

Description

Technical Field

[0001] The present invention relates to the field of circuit boards, and in particular to a method for manufacturing gold-plated fingers of a circuit board and the circuit board. Background Art

[0002] With the widespread popularity of AI technology, the demand for circuit boards used for image processing and data processing in AI servers is growing. Such circuit boards are generally gold finger card boards plugged into the server. They require high electrical reliability and stable contact signal transmission. There should be no signal attenuation, data transmission errors or intermittent circuit breaks during operation.

[0003] In the related art, when making gold fingers, it is necessary to connect the lead to one end of the gold finger pattern, and then load the current to the lead through the exposed copper area for gold plating. If the loaded current is too large and the lead width is insufficient, it will cause overheating or even burning, and at the same time, the gold finger will be burned. In addition, this gold plating method will cause the thickness of different areas of the gold finger to vary too much. For example, uneven gold thickness will lead to inconsistent conductive cross-sectional areas in the contact area, and the resistance of the thin gold area will increase, while the resistance of the thick gold area will be smaller. During plugging and unplugging or long-term use, the contact resistance may fluctuate with pressure changes. For high current scenarios, the current density in the thick gold area is low, and the current density in the thin gold area is high. Local overheating may cause the plating to burn or oxidize, further aggravating poor contact. Summary of the Invention

[0004] In view of this, the present invention provides a method for manufacturing gold-plated fingers of a circuit board and a circuit board, which can obtain better plating layer and gold thickness uniformity.

[0005] The purpose of the present invention is achieved through the following technical solutions: In one aspect, a method for manufacturing gold-plated fingers of a circuit board is provided, comprising the following steps: S1. Fabricating the outer layer pattern of the circuit board: while fabricating the outer layer pattern, fabricating the gold finger area; the gold finger area includes the gold finger pattern, the exposed copper area, a first lead extending from the exposed copper area, and a second lead extending from the middle of the gold finger pattern; the first lead and the second lead are interconnected, and the width of the second lead is greater than the width of the first lead; S2, solder resist: applying solder resist ink to the non-gold finger area of ​​the circuit board; S3, gold-plated fingers: clamping two gold-plated clips at different positions of the copper-exposed area and applying current to the two gold-plated clips to form a gold-plated layer on the gold-finger pattern; S4, peripheral molding: milling away the substrate, the copper exposed area, and part of the first lead and the second lead on the periphery of the circuit board to form a gold finger board with a final outline.

[0006] In the above technical solution, by respectively leading out a first lead and a wider second lead from the exposed copper area and the middle of the gold finger pattern and connecting them, two current paths are created. In this way, even when the current is overloaded, the first lead will be burned first, while the second lead will avoid being burned due to its larger line width, thereby protecting the gold finger, ensuring the integrity of the gold finger, and improving the processing safety of the gold finger.

[0007] In addition, a wider second lead extending from the middle of the gold finger pattern plays a key role as a current "collector" or "repeater", effectively overcoming the problem of low current density at the far end of the gold finger (far away from the exposed copper area) and high current density at the near end (close to the exposed copper area) under the traditional single lead method, making the gold plating layer thickness more uniform along the entire length of the gold finger, thereby improving product quality and reliability.

[0008] Optionally, in a possible implementation, there are a plurality of gold finger patterns arranged at intervals, two adjacent gold finger patterns are connected through the same second lead, and each second lead is connected to the copper exposed area through at least one first lead.

[0009] In the above technical solution, adjacent gold finger patterns share a second lead, and this second lead is connected to the exposed copper area through at least one first lead. This significantly reduces the number of leads extending from the gold finger area, making the lead wiring structure simpler, which is conducive to the design of high-density and multiple gold fingers.

[0010] In addition, the second lead acts as a low-impedance common bus connecting multiple gold finger patterns. The shared second lead greatly reduces the path resistance difference between the current flowing into the point from the first lead to each gold finger pattern. Multiple gold finger patterns are connected in parallel through the low-impedance second lead, so that the potential difference between them is extremely small, and the current can be more evenly distributed to all gold finger patterns, thereby significantly improving the consistency of their gold plating thickness.

[0011] Optionally, in a possible implementation manner, two of the gold finger patterns located at both ends of the gold finger area are each connected to a second lead at a middle portion of an outer side thereof.

[0012] In the above technical solution, each end gold finger pattern is independently connected to a dedicated second lead in the middle of its outer side, which can provide the most direct current path for each end gold finger pattern and ensure the current density flowing to the gold finger patterns at both ends. That is, through targeted compensation, it is ensured that the gold finger pattern at the outermost edge can also obtain a gold plating layer with the same thickness and density as the inner gold finger pattern, eliminating the uneven plating caused by the "edge effect".

[0013] Optionally, in a possible implementation, the line width of the first lead is 4-6 mil.

[0014] In the above technical solution, the line width of the first lead is set to 4-6 mil, which can meet the basic requirement of smoothly and appropriately transmitting the current in the exposed copper area to the second lead, avoiding excessive resistance and poor current transmission due to the line width being too narrow, which affects the current stability in the initial stage of gold plating.

[0015] Optionally, in a possible implementation, the line width of the second lead is 7-9 mil.

[0016] In the above technical solution, the second lead line width is set to 7-9 mils. The relatively wider line width can carry a larger current, ensuring that the current can be evenly and adequately distributed to the multiple gold finger patterns connected to it, effectively ensuring the thickness uniformity and quality stability of the gold plating layer in the gold finger area, and achieving the best gold plating effect.

[0017] Optionally, in a possible implementation, the gold finger area is close to an edge of the circuit board, and a substrate area is further provided between the copper exposed area and the edge of the circuit board.

[0018] In the above technical solution, the buffering effect of the substrate area can reduce the risk of damage to the gold finger area caused by improper edge treatment of the circuit board. Furthermore, the provision of the substrate area can reduce the area of ​​exposed copper. When the gold plating clip is clamped on the exposed copper area, when current is applied to the gold plating clip, most of the current is diverted to the exposed copper area, resulting in less current actually flowing to the gold finger pattern and thus wasting gold salt. Therefore, the smaller copper plating area design can effectively improve the gold plating effect.

[0019] Optionally, in a possible implementation, in step S4, the substrate, the exposed copper area, and part of the first lead and the second lead on the periphery of the circuit board are removed by a milling cutter or a drill.

[0020] In the above technical solution, the milling operation is performed using a milling cutter or a drill, which can accurately control the processing path and depth, ensuring that the substrate, exposed copper area, and part of the first lead and the second lead on the periphery of the circuit board are accurately removed, thereby forming a precise contour and size that meets the design requirements.

[0021] Optionally, in a possible implementation, when removing part of the first lead and the second lead, it is necessary to drill through the connection portion of the first lead and the second lead between two adjacent gold finger patterns to disconnect the two adjacent gold finger patterns.

[0022] In the above technical solution, the electrical connection between adjacent gold fingers is disconnected, so that each gold finger remains electrically independent, avoiding signal interference, short circuit or leakage caused by residual leads, ensuring that each gold finger can transmit signals accurately and stably, meeting the strict requirements of high-precision electronic equipment for signal integrity and reliability.

[0023] Optionally, in a possible implementation manner, the diameter of the milling cutter or the drill is more than 1.5 times the line width of the second lead.

[0024] In the above technical solution, using a milling cutter or drill with a tool diameter at least 1.5 times the width of the second lead ensures that when removing the lead connection between adjacent gold fingers, the tool can completely cover the target area in one go, avoiding multiple machining operations or incomplete machining due to an undersized tool. This not only improves machining efficiency but also ensures the accuracy of the removal operation.

[0025] On the other hand, a circuit board is provided, including a gold finger board manufactured by the above-mentioned manufacturing method.

[0026] In the aforementioned technical solution, the gold finger board produced using the aforementioned manufacturing method features precisely machined gold finger areas, ensuring good electrical isolation between adjacent gold fingers and uniform gold finger thickness, effectively preventing signal interference and short circuits. This ensures a stable and reliable electrical connection when connecting the circuit board to external devices, ensuring accurate and complete signal transmission. This makes it particularly suitable for applications such as high-speed data transmission and precision control, which place stringent demands on signal quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 This is a schematic diagram of the outer layer graphic design of an embodiment.

[0029] Figure 2 This is a structural diagram of a molded gold finger plate according to an embodiment.

[0030] Figure numerals: 1-gold finger pattern; 2-exposed copper area; 3-first lead; 4-second lead; 5-gold-plated clip; 6-substrate area; 7-solder mask area; 8-drilling, 9-milling groove. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0033] On the one hand, please refer to Figure 1 This embodiment provides a method for manufacturing gold-plated fingers of a circuit board, comprising the following steps: S1. Fabricating the outer layer pattern of the circuit board: While fabricating the outer layer pattern, a gold finger area is also fabricated. Both the outer layer pattern and the gold finger area are processed by etching. The gold finger area includes a gold finger pattern 1, an exposed copper area 2, a first lead 3 extending from the exposed copper area 2, and a second lead 4 extending from the middle of the gold finger pattern 1. The first lead 3 and the second lead 4 are interconnected, and the width of the second lead 4 is greater than the width of the first lead 3. S2, solder mask: Apply solder mask ink to the non-gold finger area of ​​the circuit board to form solder mask area 7; before applying solder mask, it is necessary to inspect the outer layer pattern, including checking the integrity and etching effect of the outer layer circuit pattern and the gold finger area; S3, gold-plated finger: clamp two gold-plated clips 5 at different positions of the exposed copper area 2, and apply current to the two gold-plated clips 5 to form a gold-plated layer on the gold-finger pattern 1; S4, peripheral molding: Milling away the substrate, exposed copper area 2, and portions of the first and second leads 3 and 4 from the periphery of the circuit board to form the final outline of the gold finger board. After molding, the gold finger board must undergo electrical testing and final inspection before packaging and shipment.

[0034] It should be noted that the circuit board of this embodiment has already undergone multiple pre-production processes before the outer layer pattern is fabricated, including cutting, inner layer circuit fabrication, inner layer pattern inspection, browning and lamination, cutting and shaping, through-hole drilling, and copper electroplating. During the outer layer pattern fabrication process, the required outer layer circuit pattern is etched, along with the gold finger pattern 1, the conductive exposed copper area 2 for connection to the gold plating clip 5, and the leads required for connecting the gold fingers. The conventional gold finger design process involves applying current to the exposed copper area 2 through the gold plating clip 5, which then transmits the plating current to the gold fingers via leads. If the applied current is too high or the lead width (cross-sectional area) is insufficient, overheating or burning may occur, which can also damage the gold fingers.

[0035] Therefore, this embodiment creates two current paths by extending a first lead 3 and a wider second lead 4 from the exposed copper area 2 and the middle of the gold finger pattern 1, and connecting them. When the two gold-plated clips 5 are clamped at different positions of the exposed copper area 2, the current can be more evenly distributed over the entire gold finger pattern 1. In this way, even when the current is overloaded, the first lead 3 will be burned first, while the second lead 4 will avoid being burned due to its larger line width, thereby protecting the gold finger, ensuring the integrity of the gold finger, and improving the processing safety of the gold finger.

[0036] In addition, the wider second lead 4 extending from the middle of the gold finger pattern 1 plays a key role as a current "collector" or "repeater", effectively overcoming the problem of low current density at the far end of the gold finger (far away from the exposed copper area 2) and high current density at the near end (close to the exposed copper area 2) under the traditional single lead method, making the gold plating layer thickness more uniform along the entire length of the gold finger, thereby improving product quality and reliability.

[0037] In this embodiment, multiple gold finger patterns 1 are arranged at intervals. Two adjacent gold finger patterns 1 are connected by the same second lead 4, and each second lead 4 is connected to the exposed copper area 2 via at least one first lead 3. The multiple gold finger patterns 1 are arranged along the same horizontal line. The spacing between the multiple gold finger patterns 1 can be set according to actual needs and can be the same or different. However, the spacing between two adjacent gold finger patterns 1 must be greater than the width of the first lead 3.

[0038] Multiple second leads 4 are located on the same horizontal line, which can be understood as a single second lead 4 running through the middle of all gold finger patterns 1. There can be one or more first leads 3 between two adjacent gold finger patterns 1, and the first lead 3 and second lead 4 are perpendicular to each other, with multiple first leads 3 arranged in parallel.

[0039] In this embodiment, adjacent gold fingers share a second lead 4, and this second lead 4 is connected to the exposed copper area 2 through at least one first lead 3. This significantly reduces the number of leads extending from the gold finger area, making the lead wiring structure simpler, saving wiring space, and facilitating the design of high-density, multi-gold fingers.

[0040] In addition, the second lead 4 acts as a low-impedance common bus bar connecting multiple gold finger patterns 1. The shared second lead 4 greatly reduces the difference in path resistance between the current flowing from the first lead 3 into the point to each gold finger pattern 1. Multiple gold finger patterns 1 are connected in parallel through the low-impedance second lead 4, so that the potential difference between them is extremely small, and the current can be more evenly distributed to all gold finger patterns 1, thereby significantly improving the consistency of their gold plating thickness.

[0041] It should be noted that the second lead 4 is further designed to cross the middle position of the gold finger pattern 1 (the actual connection position of the gold finger when inserted into the server slot is the middle position of the gold finger). Furthermore, the wiring density of the first lead 3 connecting the second lead 4 is increased, forming a more integrated current transmission network. This makes the current density loaded on each gold finger more similar, making the plating layer and gold thickness on each gold finger pattern 1 more uniform, and the gold thickness tolerance on the gold finger pattern 1 smaller.

[0042] In this embodiment, the two gold finger patterns 1 at both ends of the gold finger area are each connected to a second lead 4 at the middle of their outer sides. The two second leads 4 are also connected to the copper exposed area 2 through a first lead 3 respectively.

[0043] By independently connecting a dedicated second lead 4 to the middle of the outer side of each end gold finger pattern 1, the most direct current path can be provided for each end gold finger pattern 1, ensuring the current density flowing to the gold finger patterns 1 at both ends. That is, through targeted compensation, it is ensured that the gold finger pattern 1 at the outermost edge can also obtain a gold plating layer with the same thickness and density as the inner gold finger pattern 1, eliminating the uneven plating caused by the "edge effect".

[0044] As you can see, the central gold finger group is optimized by sharing the second lead 4, while the end gold fingers are compensated by independent second leads 4, forming a dual protection mechanism of "group optimization + endpoint reinforcement." Even if encountering slight deviations in the pinch point position or fluctuations in solution concentration in actual production, this design can better maintain the uniformity of the coating on all gold fingers (especially the fragile end).

[0045] In this embodiment, the line width of the first lead 3 is 4-6 mils, and the line width of the second lead 4 is 7-9 mils. The cross-sectional area of ​​the second lead 4 is larger than that of the first lead 3, and the impedance is greatly reduced.

[0046] The first lead 3 is set to a width of 4-6 mils, ensuring smooth and adequate current transfer from the exposed copper area 2 to the second lead 4. This avoids excessive resistance and poor current transfer caused by a narrower line width, which could affect current stability during the initial gold plating phase. The second lead 4 is set to a width of 7-9 mils. This wider line width can carry a higher current, ensuring that current is evenly and adequately distributed to the multiple gold finger patterns 1 connected to it, effectively ensuring the thickness uniformity and quality stability of the gold plating layer in the gold finger area, and achieving the best gold plating effect.

[0047] Specifically, the 4-6 mil first lead 3 width is a mature, stable, and high-yield conventional line width in PCB processing. Etching precision is easily controlled, and the risk of wire breakage / short circuits is extremely low. While the 7-9 mil second lead 4 width is significantly wider, it remains within the capabilities of conventional etching processes. This achieves low impedance while avoiding the risks of etching residue (residual copper), excessive undercutting, or pattern transfer distortion associated with overly wide lines.

[0048] In this embodiment, the gold finger area is close to the edge of the circuit board, and a substrate area 6 is provided between the copper exposed area 2 and the edge of the circuit board.

[0049] The exposed copper area 2 serves as the clamping area for the gold plating clip 5. Since the gold plating clip 5 is typically a metal tooth-shaped fixture, if the exposed copper area 2 is located directly at the edge of the board, the sharp teeth of the fixture can easily scratch the surface of the exposed copper area 2 during clamping, compromising conductivity. The base material area 6, through its cushioning effect, can reduce the risk of damage to the gold finger area caused by improper board edge treatment.

[0050] Furthermore, the provision of substrate area 6 can reduce the area of ​​exposed copper area 2. The gold plating clip 5 is clamped onto the exposed copper area 2. When current is applied to the gold plating clip 5, most of the current is diverted to the exposed copper area 2, resulting in less current actually flowing to the gold finger pattern 1 and wasted gold salt. Therefore, a smaller copper plating area design can effectively improve the gold plating effect. As can be understood, due to the potential difference, the gold plating thickness is thicker in areas closer to the gold plating clip 5. However, the gold finger pattern 1 receives current through the first lead 3, resulting in a gradually thinner gold plating thickness from top to bottom of the gold finger pattern 1, and poor gold thickness uniformity. The exposed copper area 2 acts as a medium, rather than as an active component of the circuit board, resulting in thick gold plating, resulting in wasted gold salt and, worse, suboptimal gold finger performance. Therefore, appropriately reducing the area of ​​the exposed copper area 2 can improve material utilization and gold plating efficiency.

[0051] In step S4 of this embodiment, the substrate, the copper exposed area 2 , and a portion of the first lead 3 and the second lead 4 on the periphery of the circuit board are removed by a milling cutter or a drill.

[0052] The use of a milling cutter or a drill for milling operation can precisely control the processing path and depth, ensuring that the substrate, the exposed copper area 2, and part of the first lead 3 and the second lead 4 on the periphery of the circuit board are accurately removed, thereby forming a precise contour and size that meets the design requirements.

[0053] Please refer to Figure 2 When removing part of the first lead 3 and the second lead 4, it is necessary to drill through the connection between the first lead 3 and the second lead 4 between two adjacent gold finger patterns 1, so that a drill hole 8 or a milling groove 9 is formed at the connection between the first lead 3 and the second lead 4, so that the two adjacent gold finger patterns 1 are disconnected, and the remaining first lead 3 or second lead 4 is not bridged with each other and does not affect the use function of the gold finger board.

[0054] Disconnecting the electrical connections between adjacent gold fingers allows each gold finger to remain electrically independent, avoiding signal interference, short circuits, or leakage caused by residual leads. This ensures that each gold finger can transmit signals accurately and stably, meeting the stringent requirements of high-precision electronic equipment for signal integrity and reliability.

[0055] It should be noted that the diameter of the milling cutter or drill should be at least 1.5 times the width of the second lead 4. Using a milling cutter or drill with a diameter at least 1.5 times the width of the second lead 4 ensures that when removing the lead connection between adjacent gold fingers, the tool can completely cover the target area in one go, avoiding multiple processing or incomplete processing due to an undersized tool. This not only improves processing efficiency but also ensures the accuracy of the removal operation.

[0056] In another aspect, this embodiment also provides a circuit board comprising a gold finger board manufactured using the aforementioned method. The gold finger board produced using the aforementioned method features precisely machined gold finger areas, ensuring good electrical isolation between adjacent gold fingers and uniform gold finger thickness, effectively preventing signal interference and short circuits. This ensures a stable and reliable electrical connection when connected to external devices, ensuring accurate and complete signal transmission. This makes it particularly suitable for applications such as high-speed data transmission and precision control, which require stringent signal quality.

[0057] In the description of the present invention, it should be understood that terms such as "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0059] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing gold-plated fingers of a circuit board, characterized in that: The following steps are involved: S1. Fabricating the outer layer pattern of the circuit board: while fabricating the outer layer pattern, fabricating the gold finger area; the gold finger area includes the gold finger pattern, the exposed copper area, a first lead extending from the exposed copper area, and a second lead extending from the middle of the gold finger pattern; the first lead and the second lead are interconnected, and the width of the second lead is greater than the width of the first lead; S2, solder resist: applying solder resist ink to the non-gold finger area of ​​the circuit board; S3, gold-plated fingers: clamping two gold-plated clips at different positions of the copper-exposed area and applying current to the two gold-plated clips to form a gold-plated layer on the gold-finger pattern; S4, peripheral molding: milling away the substrate, the copper exposed area, and part of the first lead and the second lead on the periphery of the circuit board to form a gold finger board with a final outline.

2. The method for manufacturing gold-plated fingers of a circuit board according to claim 1, characterized in that: The gold finger patterns are multiple and spaced apart, two adjacent gold finger patterns are connected through the same second lead, and each second lead is connected to the copper exposed area through at least one first lead.

3. The method for manufacturing gold-plated fingers of a circuit board according to claim 2, characterized in that: The two gold finger patterns located at both ends of the gold finger area are each connected to a second lead at the middle of the outer side thereof.

4. The method for manufacturing gold-plated fingers of a circuit board according to claim 1, characterized in that: The line width of the first lead is 4-6 mil.

5. The method for manufacturing gold-plated fingers of a circuit board according to claim 4, characterized in that: The line width of the second lead is 7-9 mil.

6. The method for manufacturing gold-plated fingers of a circuit board according to claim 1, characterized in that: The gold finger area is close to the board edge of the circuit board, and a substrate area is further provided between the copper exposed area and the board edge of the circuit board.

7. The method for manufacturing gold-plated fingers of a circuit board according to claim 2, characterized in that: In step S4, the substrate, the exposed copper area, and a portion of the first lead and the second lead on the periphery of the circuit board are removed by a milling cutter or a drill.

8. The method for manufacturing gold-plated fingers of a circuit board according to claim 7, characterized in that: When removing part of the first lead and the second lead, it is necessary to drill through the connection between the first lead and the second lead between two adjacent gold finger patterns to disconnect the two adjacent gold finger patterns.

9. The method for manufacturing gold-plated fingers of a circuit board according to claim 7, characterized in that: The diameter of the milling cutter or the drill is more than 1.5 times the width of the second lead.

10. A circuit board, characterized in that: The invention comprises a gold finger board manufactured by the manufacturing method according to any one of claims 1 to 9.

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