A circuit board pad gold plating method and circuit board

Abstract

The application discloses a circuit board pad gold plating method and a circuit board. A pattern connection layer connecting each pad precursor is formed on a sacrifice layer covering the pad precursor. The pattern connection layer comprises a body part, a connection part and a conductive lead. A part of the sacrifice layer between the edge area of the first nickel gold layer and the pattern connection layer forms an isolation ring. A part of the sacrifice layer corresponding to the vertical projection of the annular window on the sacrifice layer is removed. The side wall of the pad precursor is exposed, and the conductive lead is suspended. A second nickel gold layer is formed on the side wall of the pad precursor and the surface of the conductive lead by using an electroplating process. The pattern connection layer outside the annular window is removed, and the conductive lead is disconnected. Since the isolation ring exists between the edge area of the first nickel gold layer and the pattern connection layer, the second nickel gold layer can be prevented from spreading to the conductive lead in the electroplating process. The second nickel gold layer is integrated with the conductive lead, so that the problem of the residual conductive lead is avoided, and the quality of the circuit board is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board processing, in particular to a circuit board pad gold plating method and a circuit board. BACKGROUND

[0002] In order to store and use, the circuit board uses a plating layer to protect the surface of the pad, and different surface treatment methods are adopted according to different uses. The most common surface treatment method is tin spraying, which is relatively cheap and has high solderability, and is applied to most products in China. However, due to the particularity of the tin spraying process, it is difficult to control the tin spraying for products with high requirements for pad flatness and precision. Therefore, the nickel gold plating process is extended. The nickel gold plating process can improve the flatness of the pad surface, and has the advantages of not easy to oxidize, high hardness, strong wear resistance, good electrical conductivity and the like, thereby being widely used.

[0003] In the nickel gold plating process, the dispersed pads on the circuit board are connected by conductive leads as electrodes for electroplating. After electroplating is completed, the conductive leads are removed by etching process. Since the conductive leads are also plated with nickel gold during the electroplating of nickel gold, nickel gold residues, i.e. suspended nickel gold or lead residues, are generated after the removal of the conductive leads. The residual leads may fall off during assembly and use, causing short circuit of the circuit, and reducing the quality of the circuit board. SUMMARY

[0004] The present application provides a circuit board pad gold plating method and a circuit board, which can avoid the problem of lead residue after pad nickel gold plating, and improve the quality of the circuit board.

[0005] In a first aspect, the present application provides a circuit board pad gold plating method, comprising:

[0006] A plurality of mutually insulated pad precursors are prepared on a substrate layer, the pad precursor comprising a pad body and a first nickel gold layer, the pad body being formed on the substrate layer, and the first nickel gold layer being formed on the surface of the pad body away from the substrate layer;

[0007] A sacrificial layer covering the substrate layer and the pad precursor is formed;

[0008] A patterned connection layer electrically connecting each of the pad precursors is formed on the sacrificial layer, the patterned connection layer comprising a body portion, a connection portion and a conductive lead, the body portion being formed on the surface of the sacrificial layer away from the substrate layer, the connection portion penetrating the sacrificial layer and connecting with the first nickel gold layer, the body portion being provided with an annular window, the annular window surrounding the pad precursor, one end of the conductive lead being connected with the connection portion, the other end of the conductive lead being connected with the body portion across the annular window, and a part of the sacrificial layer between the edge region of the first nickel gold layer and the patterned connection layer forming an isolation ring.

[0009] Removing a part of the sacrificial layer corresponding to a vertical projection of the annular opening on the sacrificial layer, exposing a sidewall of the pad precursor, and leaving the conductive lead suspended;

[0010] Shielding the patterned connection layer outside the annular opening, and forming a second nickel-gold layer on the sidewall of the pad precursor and the surface of the conductive lead by electroplating process;

[0011] Removing the patterned connection layer outside the annular opening, and disconnecting the conductive lead;

[0012] Removing the sacrificial layer.

[0013] Optionally, a plurality of mutually insulated pad precursors are prepared on the substrate layer, comprising:

[0014] Providing a substrate, the substrate comprising a substrate layer and a conductive layer, the conductive layer being disposed on at least one of the two opposite surfaces of the substrate layer;

[0015] Forming a first nickel-gold layer on the conductive layer at a predetermined position where a pad precursor is to be formed;

[0016] Removing the area of the conductive layer not covered by the first nickel-gold layer, and forming a plurality of mutually insulated pad precursors on the substrate layer.

[0017] Optionally, a patterned connection layer electrically connecting each of the pad precursors is formed on the sacrificial layer, comprising:

[0018] Patternizing the sacrificial layer to form a first opening at a position corresponding to the pad precursor, exposing a central region of the first nickel-gold layer, and an edge region of the first nickel-gold layer not exposed surrounding the central region;

[0019] Forming a connection layer on the sacrificial layer, and a part of the sacrificial layer between the edge region of the first nickel-gold layer not exposed and the connection layer forming an isolation ring;

[0020] Patternizing the connection layer to obtain the patterned connection layer.

[0021] Optionally, the patterned connection layer is obtained by patternizing the connection layer, comprising:

[0022] Forming a first photosensitive layer on the connection layer;

[0023] Patternizing the first photosensitive layer to form a shielding ring at a position where an annular opening is to be formed, and the shielding ring being provided with an opening at a position where a conductive lead is to be formed;

[0024] An area of the connection layer not covered by the shielding ring forms a protection layer;

[0025] The first photosensitive layer is removed.

[0026] The connection layer not covered by the protection layer is removed to obtain the patterned connection layer.

[0027] The protection layer is removed.

[0028] Optionally, before the connection layer is patterned, the method further comprises:

[0029] The connection layer is thickened by electroplating.

[0030] Optionally, the patterned connection layer outside the annular window is shielded, and a second nickel-gold layer is formed on the sidewall of the pad precursor and the surface of the conductive lead by electroplating, comprising:

[0031] A second photosensitive layer is formed on the patterned connection layer.

[0032] The second photosensitive layer is patterned, the patterned connection layer outside the annular window is shielded, and the conductive lead is exposed.

[0033] A second nickel-gold layer is formed on the sidewall of the pad precursor and the surface of the conductive lead by electroplating.

[0034] The second photosensitive layer is removed.

[0035] Optionally, when the distance between the first pad precursor and the second pad precursor is less than a set distance, one end of the conductive lead is connected to the connection part on the first pad precursor across the annular window of the first pad precursor, and the other end of the conductive lead is connected to the connection part on the second pad precursor across the annular window of the second pad precursor.

[0036] Optionally, the distance between the outer ring and the inner ring of the annular window ranges from 4 mil to 6 mil.

[0037] Optionally, the line width of the conductive lead ranges from 5 mil to 10 mil, and the thickness of the conductive lead ranges from 40 μm to 60 μm.

[0038] In a first aspect, the present application provides a circuit board prepared by the method for gold plating of a circuit board pad according to the first aspect of the present application.

[0039] The present application provides a circuit board pad gold plating method, a plurality of mutually insulated pad precursors are prepared on a substrate layer, the pad precursor comprises a pad body and a first nickel-gold layer, the pad body is formed on the substrate layer, and the first nickel-gold layer is formed on the surface of the pad body away from the substrate layer; a sacrificial layer covering the substrate layer and the pad precursor is formed; a pattern connection layer electrically connecting each pad precursor is formed on the sacrificial layer; the pattern connection layer comprises a body part, a connecting part and a conductive lead, the body part is formed on the surface of the sacrificial layer away from the substrate layer, the connecting part is connected with the first nickel-gold layer through the sacrificial layer, the body part is provided with an annular window, the annular window surrounds the pad precursor, one end of the conductive lead is connected with the connecting part, the other end of the conductive lead is connected with the body part across the annular window, and part of the sacrificial layer between the edge region of the first nickel-gold layer and the pattern connection layer forms an isolation ring; then the corresponding part of the sacrificial layer in the vertical projection of the annular window on the sacrificial layer is removed, the side wall of the pad precursor is exposed, the conductive lead is suspended, the pattern connection layer outside the annular window is shielded, and a second nickel-gold layer is formed on the side wall of the pad precursor and the surface of the conductive lead by using an electroplating process; the pattern connection layer outside the annular window is removed, and the conductive lead is disconnected; since the isolation ring exists between the edge region of the first nickel-gold layer and the pattern connection layer, the second nickel-gold layer can be prevented from spreading to the conductive lead in the electroplating process, the second nickel-gold layer is integrated with the conductive lead, the problem of residual conductive lead is avoided, and the quality of the circuit board is improved. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0041] Figure 1 A flow chart of a circuit board pad gold plating method provided by the present application is shown in the figure.

[0042] Figure 2 A process flow chart of a circuit board pad gold plating method provided by the present application is shown in the figure.

[0043] Figure 3 A process flow chart of preparing a plurality of mutually insulated pad precursors on a substrate layer is shown in the figure.

[0044] Figure 4 A plane schematic diagram of a pattern connection layer is shown in the figure.

[0045] Figure 5 A process flow chart of preparing a pattern connection layer is shown in the figure.

[0046] Figure 6 A plane view after the first photosensitive layer is patterned is shown in the figure.

[0047] Figure 7 Process flow chart for forming the second nickel-gold layer.

[0048] The specific embodiments of the present application have been shown through the above-described drawings, and will be described in more detail later. These drawings and written descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0049] To make the technical problems solved by the present application, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present application will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0050] In the description of the present application, unless explicitly defined and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0051] In the present application, unless explicitly defined and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature. In addition, the terms "first", "second" are only used to distinguish in the description, and have no special meaning.

[0052] Figure 1 A flow chart of a circuit board pad gold plating method provided by the present application, Figure 2 A process flow chart for gold plating of a circuit board pad provided by the present application, as shown in Figure 1 、 2 The circuit board pad gold plating method comprises:

[0053] S101. A plurality of mutually insulated pad precursors are prepared on a substrate layer. The pad precursors include a pad body and a first nickel-gold layer.

[0054] like Figure 2 As shown, a plurality of mutually insulated pad precursors 120 are prepared on the substrate layer 110 of the circuit board. Exemplarily, the pad precursors 120 may be formed on one side or opposite sides of the substrate layer 110; this is not limited herein, but is illustrated by the example of pad precursors 120 being formed on opposite sides of the substrate layer 110. Exemplarily, the pad precursor 120 includes a pad body 121 and a first nickel-gold layer 122. The pad body 121 is formed on the substrate layer 110, and the first nickel-gold layer 122 is formed on the surface of the pad body 121 away from the substrate layer 110. Exemplarily, the nickel-gold layer of this invention may include a nickel layer and a gold layer, with the nickel layer formed on the pad body 121 and the gold layer covering the nickel layer. The preparation method of the pad precursors can employ existing methods, and this invention is not limited herein.

[0055] Figure 3 A process flow diagram for fabricating multiple mutually insulated pad precursors on a substrate layer, such as... Figure 3 As shown, in some embodiments of the present invention, step S101 may include the following sub-steps:

[0056] S1011. A substrate is provided, the substrate including a substrate layer and a conductive layer, the conductive layer being disposed on at least one of two opposing surfaces of the substrate layer.

[0057] In this embodiment of the invention, a substrate is provided, and the substrate can be pre-treated, for example, by cleaning, drying, etc. The substrate includes a substrate layer 110 and a conductive layer 1211. The conductive layer 1211 is disposed on at least one of two opposing surfaces of the substrate layer 110. Exemplarily, the present invention is described with the conductive layer 1211 disposed on two opposing surfaces of the substrate layer 110 as an example. Exemplarily, the conductive layer 1211 may be a copper foil.

[0058] S1012. A first nickel-gold layer is formed at a predetermined position on the conductive layer where the pad precursor is to be formed.

[0059] In this embodiment of the invention, a dry film 130 can be attached to the conductive layer 1211, and the dry film 130 can be imaged, for example, by photosensitizing and developing, to form a window 131, exposing the predetermined position of the conductive layer 1211 where the pad precursor is to be formed. Then, an electroplating process is used to electroplat a nickel layer and a gold layer on the conductive layer 1211 exposed by the window 131, respectively, to form a first nickel-gold layer 122.

[0060] S1013. Remove the area of ​​the conductive layer not covered by the first nickel-gold layer and form multiple mutually insulating pad precursors on the substrate layer.

[0061] In the embodiment of the present application, the dry film 130 is removed, and then the alkali etching process is adopted to remove the area of the conductive layer 1211 which is not covered by the first nickel-gold layer 122, thereby forming a plurality of mutually insulated pad precursors 120 on the substrate layer 110.

[0062] S102, forming a sacrificial layer covering the substrate layer and the pad precursor.

[0063] As shown in the drawings, the sacrificial layer 140 covering the substrate layer 110 and the pad precursor 120 is formed. Exemplarily, the sacrificial layer 140 can be a wet film, and the full-plate screen printing process is adopted to form the sacrificial layer 140 covering the substrate layer 110 and the pad precursor 120 on the opposite sides of the substrate layer 110. Figure 2

[0064] S103, forming a patterned connection layer electrically connecting the pad precursors on the sacrificial layer.

[0065] Figure 4 For the plan view of the patterned connection layer, the structure above the substrate layer 110 in the process flow chart of the present application is shown in the cross section along the cross section line A-A' in the drawings, and the structure below the substrate layer 110 can be the same as or different from the structure above the substrate layer 110, which is not limited in the present application. Referring to the drawings of Figure 4 and Figure 2 , the patterned connection layer 151 can be formed by patterning the conductive layer, and the patterned connection layer 151 includes a body part 1511, a connecting part 1512 and a conductive lead 1513. The body part 1511 is formed on the surface of the sacrificial layer 140 away from the substrate layer 110, the connecting part 1512 penetrates the sacrificial layer 140 and is connected with the first nickel-gold layer 122, and the body part 1511 is provided with an annular window 1514 surrounding the pad precursor 120. Exemplarily, the inner edge of the annular window 1514 coincides with the edge of the pad precursor 120. One end of the conductive lead 1513 is connected with the connecting part 1512, and the other end of the conductive lead 1513 is connected with the body part 1511 across the annular window 1514, so that the pad precursors 120 are electrically connected through the patterned connection layer 151. There is part of the sacrificial layer 140 between the edge area of the first nickel-gold layer 122 and the patterned connection layer 151. It should be noted that, since the conductive lead 1513 crosses the annular window 1514, the annular window 1514 is not a closed annular shape, but has a gap at the position corresponding to the conductive lead 1513. Figure 4

[0066] ​​In some embodiments of the present invention, for two pad precursors whose distance D1 between them is less than a set distance, the first pad precursor and the second pad precursor can be directly connected by a conductive lead 1513. For example, one end of the conductive lead 1513 crosses the annular opening 1514 of the first pad precursor and connects to the connection portion 1512 on the first pad precursor, and the other end of the conductive lead 1513 crosses the annular opening 1514 of the second pad precursor and connects to the connection portion 1512 on the second pad precursor. For two pad precursors whose distance D2 between them is greater than or equal to a set distance Dset, since the conductive lead 1513 needs to be suspended later, in order to avoid the conductive lead 1513 spanning too long and breaking due to its own weight, the conductive lead 151 only crosses the annular opening 1514, with one end connected to the connection portion 1512 on the pad precursor 120 and the other end connected to the body portion 1511.

[0067] In some embodiments of the present invention, the distance between the outer ring and the inner ring of the annular window 1514 is 4mil-6mil. On the one hand, the distance between the outer ring and the inner ring of the annular window 1514 needs to be large enough so that when the sacrificial layer 140 is rinsed with developer in step S104, the developer in the corresponding trench of the annular window 1514 has good fluidity and exposes the sidewall of the pad precursor 120. On the other hand, the distance between the outer ring and the inner ring of the annular window 1514 cannot be too large to avoid the problem that the conductive lead 1513 will break due to excessive span when the conductive lead 1513 is suspended in step S104.

[0068] In some embodiments of the present invention, the linewidth of the conductive lead 1513 is in the range of 5mil-10mil, and the thickness of the conductive lead 1513 is in the range of 40μm-60μm. This ensures that the conductive lead 1513 has sufficient rigidity and avoids the problem of the conductive lead 1513 breaking due to insufficient rigidity when the conductive lead 1513 is suspended in the subsequent S104 step.

[0069] Figure 5 A process flow diagram for fabricating the patterned interconnect layer, such as... Figure 2 , 4 As shown in Figure 5, in some embodiments of the present invention, step S103 above includes the following sub-steps:

[0070] S1031. The sacrificial layer is patterned to form a first window at the corresponding position of the pad front, exposing the central area of ​​the first nickel-gold layer, while the unexposed edge area of ​​the first nickel-gold layer surrounds the central area.

[0071] like Figure 5As shown, in the embodiment of the present application, the sacrificial layer 140 is subjected to a patterning process to form a first opening window 142 at the position corresponding to the pad precursor 120, thereby exposing the central region of the first nickel-gold layer 122, and the edge region of the first nickel-gold layer 122 which is not exposed surrounds the central region, thus ensuring that the edge region of the first nickel-gold layer 122 is covered with the sacrificial layer 140. For example, the first opening window 142 is concentrically arranged with the first nickel-gold layer 122. For example, as described above, the sacrificial layer 140 is a wet film, and the wet film can be subjected to a mask, photosensitive, development and other processes to form the first opening window 142 at the position corresponding to the pad precursor 120.

[0072] S1032, forming a connection layer on the sacrificial layer, and the part of the sacrificial layer between the edge region of the first nickel-gold layer which is not exposed and the connection layer forms an isolation ring.

[0073] In the embodiment of the present application, the connection layer 150 is a copper layer, and for example, a copper foil with a thickness of 5-7 μm can be formed on the surface of the sacrificial layer 140 by a copper deposition or electroplating process. After the connection layer 150 is formed, there is part of the sacrificial layer 140 between the edge region of the first nickel-gold layer 122 which is not exposed and the connection layer 150, which is used to isolate the connection layer 150 and the first nickel-gold layer 122 in the direction perpendicular to the circuit board.

[0074] S1033, thickening the connection layer by an electroplating process.

[0075] In some embodiments of the present application, in order to ensure that the conductive lead 1513 in the patterned connection layer 151 formed later has a suitable thickness, the connection layer 150 can be thickened by an electroplating process, so that the thickness of the connection layer 151 is controlled within the range of 40-60 μm.

[0076] S1033, patterning the connection layer to obtain a patterned connection layer.

[0077] After the connection layer 150 is formed, the connection layer 150 is subjected to a patterning process to obtain a patterned connection layer 151, and the specific patterning process is not limited in the present application.

[0078] In some embodiments of the present application, as shown in the above step S1033 can include the following sub-steps: Figure 5

[0079] 1. Forming a first photosensitive layer on the connection layer.

[0080] A first photosensitive layer 160 is formed on the connection layer 150, and for example, the first photosensitive layer 160 can be a dry film.

[0081] ​2. Perform a patterning process on the first photosensitive layer to form a shielding ring at the position where the annular opening window is to be formed, and the shielding ring is provided with an opening at the position where the conductive lead is to be formed.

[0082] Figure 6 As shown in the plan view of the first photosensitive layer after the patterning process, Figure 6 In the embodiment of the present application, the first photosensitive layer 160 is subjected to a patterning process, such as mask, exposure, development, etc., to form a shielding ring 161 at the position where the annular opening window 1514 is to be formed, and the shielding ring 161 is not a complete ring, but is provided with an opening 1611 at the position where the conductive lead 1513 is to be formed. The portion of the connecting layer 150 exposed by the opening 1611 corresponds to the conductive lead.

[0083] In the embodiment of the present application, for two pad precursors with a distance D1 between each other less than a set distance Dset, the area between the two shielding rings 161 is also shielded and integrated with the shielding rings 161, and a linear opening 1612 is connected between the two shielding rings 161, and the portion of the connecting layer 150 exposed by the linear opening 1612 corresponds to the conductive lead. The portion of the connecting layer within the shielding ring 161 corresponds to the connecting portion, and the other portion of the connecting layer 150 not shielded corresponds to the body portion.

[0084] 3. Form a protective layer on the area of the connecting layer not shielded by the shielding ring.

[0085] In the embodiment of the present application, a protective layer 170 is formed on the area of the connecting layer 150 not shielded by the shielding ring 161. Exemplarily, the protective layer 170 covers the area of the connecting layer 150 not shielded.

[0086] Exemplarily, a tin plating process can be used to form a tin layer as the protective layer 170 on the area of the connecting layer 150 not shielded.

[0087] 4. Remove the first photosensitive layer.

[0088] The residual first photosensitive layer 160, including the shielding ring 161, and the shielding between the two pad precursors with a distance D1 between each other less than a set distance Dset, are removed.

[0089] 5. Remove the connecting layer not covered by the protective layer to obtain a patterned connecting layer.

[0090] Exemplarily, an alkaline etching process is used to retain the area covered by the protective layer 170, and remove the connecting layer 150 not covered by the protective layer 170 to obtain a patterned connecting layer 151. The plan view of the patterned connecting layer 151 is shown in FIG. 1F, and the present application will not be described here again. Figure 4

[0091] 6. Remove the protective layer. ​

[0092] After forming the patterned connection layer 151, the protective layer 170 on the patterned connection layer 151 is removed.

[0093] S104, the part of the sacrificial layer corresponding to the vertical projection of the annular window on the sacrificial layer is removed, the sidewall of the pad precursor is exposed, and the conductive lead is suspended.

[0094] In the embodiment of the present application, after forming the patterned connection layer 151, the exposed part of the sacrificial layer 140 is exposed, and then the exposed part of the sacrificial layer 140 is removed by using a developing solution to expose the sidewall of the pad precursor 120 and suspend the conductive lead 1513. For example, the part of the sacrificial layer 140 corresponding to the vertical projection of the annular window 1514 on the sacrificial layer 140 is exposed, and the part of the sacrificial layer 140 corresponding to the vertical projection of the shielding between the two pad precursors with a distance D1 less than the set distance Dset on the sacrificial layer 140 is exposed. In addition, the part of the sacrificial layer 140 between the edge region of the first nickel-gold layer 122 and the patterned connection layer 151 is not exposed, so it is retained during the developing process to form the isolation ring 141.

[0095] S105, the patterned connection layer outside the annular window is shielded, and the second nickel-gold layer is formed on the sidewall of the pad precursor and the surface of the conductive lead by using an electroplating process.

[0096] In the embodiment of the present application, the patterned connection layer 151 outside the annular window 1514 is shielded to expose the conductive lead 1513, and the second nickel-gold layer 123 is formed on the sidewall of the pad precursor 120 and the surface of the conductive lead 1513 by using an electroplating process. As shown in Figure 2 Because of the isolation ring 141 between the edge region of the first nickel-gold layer 122 and the patterned connection layer 151, the second nickel-gold layer 123 can be prevented from spreading to the conductive lead 1513 during the electroplating process, and the second nickel-gold layer 123 is integrated with the conductive lead 1513, which can prevent the conductive lead 1513 from being damaged during the subsequent process.

[0097] Figure 7 The process flow chart for forming the second nickel-gold layer is shown in Figure 7 As shown in the figure, in some embodiments of the present application, the above step S105 includes the following sub-steps:

[0098] S1051, a second photosensitive layer is formed on the patterned connection layer.

[0099] In the embodiment of the present application, the second photosensitive layer 180 can be a wet film, and the second photosensitive layer 180 is formed on the patterned connection layer 151 by using a spraying wet film method. It should be noted that this step cannot be performed by using a silk screen method to avoid the suspended conductive lead 1513 being broken by force during the silk screen process.

[0100] S1052, the second photosensitive layer is patterned to shield the pattern connection layer outside the annular window and expose the conductive lead.

[0101] The second photosensitive layer is patterned, for example, mask, exposure, development, etc. The pattern connection layer 151 outside the annular window 1514 is shielded, and the conductive lead 1513 is exposed.

[0102] S1053, a second nickel-gold layer is formed on the side wall of the pad precursor and the surface of the conductive lead by electroplating process.

[0103] In the embodiment of the application, a second nickel-gold layer 123 is formed on the side wall of the pad precursor 120 and the surface of the conductive lead 1513 by electroplating process.

[0104] S1054, the second photosensitive layer is removed.

[0105] The residual second photosensitive layer 180 is washed with developer.

[0106] S106, the pattern connection layer outside the annular window is removed, and the conductive lead is disconnected.

[0107] As shown in Figure 2 , because the conductive lead 1513 is covered by the second nickel-gold layer 123, the other areas of the pattern connection layer 151 are exposed. By using alkaline etching process, the exposed pattern connection layer 151 is removed. Because the conductive lead 1513 is connected with the other parts of the pattern connection layer 151, when the other parts of the pattern connection layer 151 are removed, the conductive lead 1513 is automatically disconnected, achieving the purpose of removing the conductive lead 1513.

[0108] S107, the sacrificial layer is removed.

[0109] As shown in Figure 2 , the residual sacrificial layer 140 is washed with developer to form a nickel-gold plated pad.

[0110] The present application provides a circuit board pad gold plating method, a plurality of mutually insulated pad precursors are prepared on a substrate layer, the pad precursor comprises a pad body and a first nickel-gold layer, the pad body is formed on the substrate layer, and the first nickel-gold layer is formed on a surface of the pad body away from the substrate layer; a sacrificial layer covering the substrate layer and the pad precursor is formed; a pattern connection layer electrically connecting each pad precursor is formed on the sacrificial layer; the pattern connection layer comprises a body part, a connecting part and a conductive lead, the body part is formed on a surface of the sacrificial layer away from the substrate layer, the connecting part is connected with the first nickel-gold layer through the sacrificial layer, the body part is provided with an annular window, the annular window surrounds the pad precursor, one end of the conductive lead is connected with the connecting part, the other end of the conductive lead is connected with the body part across the annular window, and a part of the sacrificial layer between an edge region of the first nickel-gold layer and the pattern connection layer forms an isolation ring; then a part of the sacrificial layer corresponding to a vertical projection of the annular window on the sacrificial layer is removed, a side wall of the pad precursor is exposed, and the conductive lead is suspended; the pattern connection layer outside the annular window is shielded; a second nickel-gold layer is formed on the side wall of the pad precursor and a surface of the conductive lead by using an electroplating process; the pattern connection layer outside the annular window is removed, so that the conductive lead is disconnected; since the isolation ring exists between the edge region of the first nickel-gold layer and the pattern connection layer, the second nickel-gold layer cannot spread to the conductive lead in the electroplating process, the second nickel-gold layer is integrated with the conductive lead, and the problem of residual conductive lead is avoided, thereby improving the quality of the circuit board.

[0111] The present application also provides a circuit board prepared by using the circuit board pad gold plating method provided by any one of the preceding embodiments of the present application, and has the same functions and effects.

[0112] In the description herein, it should be understood that the terms "upper", "lower", "left", "right", and the like, orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0113] In the description of the present application, the description referring to the terms "an embodiment", "an example", and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example.

[0114] In addition, it should be understood that although the present application is described in terms of embodiments, each embodiment does not necessarily contain only one independent technical solution, and the description of the present application is only for the sake of clarity, and those skilled in the art should consider the present application as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0115] The technical principles of the present application are described above in combination with specific embodiments. These descriptions are only for explaining the principles of the present application, and cannot be interpreted as limiting the protection scope of the present application in any way. Based on the explanations herein, other specific embodiments of the present application can be conceived by those skilled in the art without any creative effort, and these embodiments will all fall within the protection scope of the present application.

Claims

1. A method for gold plating a land of a circuit board, characterized by, The method comprises the following steps: preparing a plurality of mutually insulated pad precursors on a substrate layer, the pad precursors comprising a pad body and a first nickel-gold layer, the pad body being formed on the substrate layer, and the first nickel-gold layer being formed on a surface of the pad body away from the substrate layer; forming a sacrificial layer covering the substrate layer and the pad precursors; forming a patterned connection layer on the sacrificial layer, the patterned connection layer being electrically connected to each of the pad precursors, the patterned connection layer comprising a body portion, a connection portion, and a conductive lead, the body portion being formed on a surface of the sacrificial layer away from the substrate layer, the connection portion being connected to the first nickel-gold layer through the sacrificial layer, the body portion being provided with an annular window, the annular window surrounding the pad precursor, one end of the conductive lead being connected to the connection portion, the other end of the conductive lead being connected to the body portion across the annular window, and a portion of the sacrificial layer between an edge region of the first nickel-gold layer and the patterned connection layer forming an isolation ring; removing a portion of the sacrificial layer corresponding to a vertical projection of the annular window on the sacrificial layer, exposing a sidewall of the pad precursor, and leaving the conductive lead hanging; shielding the patterned connection layer except the annular window, and forming a second nickel-gold layer on the sidewall of the pad precursor and a surface of the conductive lead by electroplating; removing the patterned connection layer except the annular window, and disconnecting the conductive lead; removing the sacrificial layer.

2. The method of claim 1, wherein the gold plating of the circuit board pad is performed by a method comprising: The method comprises the following steps: preparing a plurality of mutually insulated pad precursors on a substrate layer, the method comprising the following steps: providing a substrate, the substrate comprising a substrate layer and a conductive layer, the conductive layer being arranged on at least one of two opposite surfaces of the substrate layer; forming a first nickel-gold layer on the conductive layer at predetermined positions where the pad precursors are to be formed; 3. The method of claim 1, wherein the gold plating of the circuit board pad is performed by a method comprising: removing regions of the conductive layer not covered by the first nickel-gold layer, and forming a plurality of mutually insulated pad precursors on the substrate layer. forming a patterned connection layer on the sacrificial layer, the patterned connection layer being electrically connected to each of the pad precursors, the method comprising the following steps: performing a patterning process on the sacrificial layer to form a first window at positions corresponding to the pad precursors, and exposing a central region of the first nickel-gold layer, an edge region of the first nickel-gold layer not exposed surrounding the central region; forming a connection layer on the sacrificial layer, a portion of the sacrificial layer between the edge region of the first nickel-gold layer not exposed and the connection layer forming an isolation ring; 4. The method of claim 3, wherein the gold plating is performed by electroless plating. performing a patterning process on the connection layer to obtain the patterned connection layer. performing a patterning process on the connection layer to obtain the patterned connection layer, the method comprising the following steps: forming a first photosensitive layer on the connection layer; performing a patterning process on the first photosensitive layer to form a shielding ring at positions where an annular window is to be formed, and the shielding ring being provided with an opening at positions where a conductive lead is to be formed; forming a protective layer on regions of the connection layer not shielded by the shielding ring; removing the first photosensitive layer; removing the connection layer not covered by the protective layer to obtain the patterned connection layer; 5. The method of claim 4, wherein the gold plating is performed by electroless plating. removing the protective layer. Before the patterning process on the connection layer, the method further comprises the following step: thickening the connection layer by electroplating.

6. The method of claim 1-5, wherein the gold plating of the solder pad of the circuit board is performed by a method comprising: Shielding the patterned connection layer outside the annular window, and forming a second nickel-gold layer on the sidewall of the pad precursor and the surface of the conductive lead by electroplating process, comprising: forming a second photosensitive layer on the patterned connection layer; performing a patterned treatment on the second photosensitive layer, shielding the patterned connection layer outside the annular window, and exposing the conductive lead; forming a second nickel-gold layer on the sidewall of the pad precursor and the surface of the conductive lead by electroplating process; removing the second photosensitive layer.

7. The method of claim 1-5, wherein the gold plating of the solder pad of the circuit board is performed by a method comprising: When the distance between the first pad precursor and the second pad precursor is less than a set distance, one end of the conductive lead is connected with the connection part on the first pad precursor across the annular window of the first pad precursor, and the other end of the conductive lead is connected with the connection part on the second pad precursor across the annular window of the second pad precursor.

8. The method of claim 1-5, wherein the gold plating of the solder pad of the circuit board is performed by a method comprising: The distance between the outer ring and the inner ring of the annular window ranges from 4 mil to 6 mil.

9. The method of claim 1-5, wherein the gold plating of the solder pad of the circuit board is performed by a method comprising: The line width of the conductive lead ranges from 5 mil to 10 mil, and the thickness of the conductive lead ranges from 40 μm to 60 μm.

10. A wiring board, characterized by The circuit board pad gold plating method is prepared by any one of claims 1-9. The circuit board pad gold plating method is prepared by any one of claims 1-9.

Images