Method for manufacturing circuit board with local electroplated nickel-gold bonding pad and circuit board

Abstract

The invention discloses a method for manufacturing a circuit board with a locally-electroplated nickel-gold bonding pad and the circuit board, and the method comprises the following steps in sequence: plating copper on a board surface; manufacturing an initial bonding pad pattern; plating nickel and gold on the bonding pad; primary film stripping: exposing the copper layer and the nickel-gold layer higher than the copper layer; performing positive sheet treatment: exposing the side wall surface at the joint of the copper layer and the nickel-gold layer; tin plating treatment: electroplating tin on the side wall surface to form a tin layer; secondary film stripping: stripping the dry film on the surface to expose the copper layer and the nickel-gold layer; and etching processing: removing the copper foil by using an alkaline etching solution so as to process an outer-layer circuit. Through an innovative process of firstly plating copper, locally plating nickel and gold, then etching a positive plate and tinning to protect a circuit on the side wall of the bonding pad, the problems of infirm dry film lamination and etching medicine permeation caused by the height difference between a nickel-gold bonding pad and a copper surface in a traditional method are effectively solved, the yield and reliability of the circuit are remarkably improved, and the functions of the bonding pad and the integrity of the circuit are considered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board manufacturing, in particular to a circuit board manufacturing method using a local electro-nickel-gold pad and a circuit board manufactured by the circuit board manufacturing method. BACKGROUND

[0002] In the field of printed circuit board manufacturing, there is a wide demand for circuit boards with local electro-nickel-thick-gold pads. Such circuit boards are often used in electronic devices that have high requirements for the reliability and solderability of pad connections, such as high-end chip packaging substrates and precision instrument mainboards.

[0003] A conventional circuit board manufacturing method for circuit boards with local electro-nickel-thick-gold pads generally includes the following steps: pre-processes such as basic operations such as cutting, drilling, copper deposition, plate electrification, pad pattern manufacturing, electro-nickel-gold plating, film stripping, outer layer circuit pattern manufacturing, outer layer etching, film stripping, and post-processes to produce the final circuit board.

[0004] However, the existing conventional manufacturing method first manufactures the pad and then manufactures the outer layer circuit. During the manufacturing process, the surface of the pad site after electro-nickel-gold plating is covered with a nickel and thick gold layer, which has a thickness significantly higher than the surrounding copper surface, resulting in a certain height difference between the pad site and the copper surface of the board. In this regard, when the outer layer pattern dry film is attached to manufacture the outer layer circuit, especially at the connection site between the thick gold site and the copper surface of the board, due to the height difference, the dry film is difficult to tightly attach, causing the etching chemical to easily seep into the gap at the connection site during the outer layer negative film etching. Once the chemical seeps in, it will corrode the copper layer that is not effectively protected by the dry film, causing open circuits, notches, and other abnormalities. These abnormalities not only seriously affect the appearance quality of the circuit board, such as causing surface unevenness and plating damage, but more critically, they have a significant negative impact on the electrical performance of the circuit board, such as causing line conduction failure, which in turn affects the normal operation of the entire electronic device.

[0005] Currently, there are some improvement attempts in the industry to address this issue, but most of them focus on optimizing the dry film attachment or improving the etching chemical formula, none of which addresses the core problem of the height difference caused by the process flow of first plating nickel-gold and then etching the circuit. Therefore, it is difficult to fundamentally solve the problem of low circuit processing yield and high reliability risk. SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a method for manufacturing a circuit board with local electro-nickel-gold pads, which effectively solves the problem of poor dry film adhesion and etching penetration caused by the height difference between the nickel-gold pads and the copper surface in the traditional method, significantly improves the circuit yield and reliability, and balances the pad function and circuit integrity.

[0007] The present application also proposes a circuit board manufactured by the method for manufacturing a circuit board with local electro-nickel-gold pads.

[0008] The method for manufacturing a circuit board with local electro-nickel-gold pads according to the present application comprises the following steps: Copper plating on the board surface: electroplating a copper layer with a predetermined thickness on the surface of the substrate; Manufacturing initial pad pattern: after copper plating on the board surface, sequentially applying dry film and exposure development processing to manufacture a pad preset pattern at a predetermined position of the copper layer; Pad nickel-gold plating: after manufacturing the initial pad pattern, sequentially electroplating nickel and gold on the surface of the pad preset pattern to form a nickel-gold layer on the surface of the pad preset pattern; First film removal: after pad nickel-gold plating, remove the surface dry film to expose the copper layer and the nickel-gold layer higher than the copper layer; Positive processing: after the first film removal, sequentially apply dry film, positive exposure and development processing to expose the side wall surface at the junction of the copper layer and the nickel-gold layer; Tin plating processing: after the positive processing, electroplate tin on the side wall surface to form a tin layer; Second film removal: after the tin plating processing, remove the surface dry film to expose the copper layer and the nickel-gold layer; Etching processing: after the second film removal, remove the copper foil with an alkaline etching solution to process the outer circuit.

[0009] The local electro-nickel-gold pad circuit board manufacturing method has at least the following beneficial effects: by means of copper plating first, local thick gold plating, then positive film etching and protection of the key side wall by the tin plating layer, the problem of dry film fitting caused by the high and low position difference in the traditional process is fundamentally solved, the etching chemical solution is prevented from penetrating, the yield and reliability of the circuit board manufacturing are improved; specifically, the copper plating of the board surface is performed first, which provides a basic conductive layer for subsequent circuit and pad manufacturing, then the initial pad pattern is manufactured to accurately determine the position and shape of the pad, the subsequent pad nickel-gold plating step forms a nickel-gold layer, which gives the pad good oxidation resistance, solderability and other properties to meet the high requirements of the pad in specific application scenarios, then the surface dry film is removed in the one-time film removal step to expose the copper layer and the nickel-gold layer higher than the copper layer, which prepares for subsequent processing; it is worth noting that the positive film processing is one of the key links of the method, the side wall surface at the connection between the copper layer and the nickel-gold layer is exposed by sequentially pasting the dry film, positive film exposure and development processing, and the key area to be protected can be accurately positioned; for this, the tin plating processing is performed after the positive film processing, tin is electroplated on the side wall surface to form a tin layer, the tin layer acts as an effective protection barrier to prevent the etching chemical solution from eroding the side wall at the connection between the copper layer and the nickel-gold layer in the subsequent etching process, and the problem of chemical solution penetration and copper layer corrosion caused by the dry film fitting problem in the traditional process is avoided; finally, the surface dry film is removed in the second film removal step to expose the copper layer and the nickel-gold layer, which is combined with the subsequent etching processing step to remove the copper foil by using an alkaline etching solution to process the outer circuit; further, on the basis of ensuring that the pad has good properties, the process sequence and protection mechanism are optimized, the circuit board manufactured has high reliability of the local electro-nickel-gold pad and avoids abnormal processing of the outer circuit, the overall quality and performance of the circuit board are improved, the requirements of electronic equipment on the circuit board for high precision and high reliability are better met, and the circuit board has stronger market competitiveness and wider application prospect.

[0010] In the positive film processing, the film pressing pressure of the dry film is 4.5 kg according to the local electro-nickel-gold pad circuit board manufacturing method.

[0011] The local electro-nickel-gold pad circuit board manufacturing method further includes the following steps: Manufacturing a circuit pattern: after the positive film exposure and development processing in the positive film processing, the surface of the copper layer forms an outer circuit pattern.

[0012] The local electro-nickel-gold pad circuit board manufacturing method has the pad preset pattern in a circular or square shape.

[0013] The local electro-nickel-gold pad circuit board manufacturing method further includes the following steps: Making standard pad pattern: in the positive film processing, after the positive film exposure and developing processing, the standard pad pattern is made at the corresponding position of the pad preset pattern, the pad preset pattern has a single side compensation value greater than or equal to 2 mils relative to the standard pad pattern.

[0014] According to the circuit board manufacturing method of the partial electro-nickel-gold pad, the pad preset pattern and the standard pad pattern are both circular, and the diameter of the pad preset pattern is greater than the diameter of the standard pad pattern by more than 2 mils.

[0015] According to the circuit board manufacturing method of the partial electro-nickel-gold pad, in the tin plating processing, the tin plating parameters are 14 ASF*14 min.

[0016] According to the circuit board manufacturing method of the partial electro-nickel-gold pad, the method further comprises the following steps: Tin stripping and sand blasting: after the etching processing, the tin layer is removed, and the surface of the nickel-gold layer is subjected to sand blasting processing.

[0017] According to the circuit board manufacturing method of the partial electro-nickel-gold pad, the method further comprises the following steps: Post-processing: after the tin stripping and sand blasting, a solder resist layer, a surface treatment process and a forming process are sequentially made to produce a circuit board.

[0018] According to the circuit board, the circuit board is manufactured by using the circuit board manufacturing method of the partial electro-nickel-gold pad.

[0019] According to the circuit board, at least the following beneficial effects are achieved: due to the adoption of the processes of copper plating and pad nickel-gold plating, and the optimization process steps of positive film processing, tin plating protection and positive film etching, the circuit board effectively solves the problem of tin penetration caused by the height difference between the pad and the copper surface in the traditional manufacturing method, improves the electrical performance and reliability of the circuit board, and reduces the occurrence of defects such as open circuit and gap; at the same time, through reasonable process parameter setting and additional processing steps such as specific film pressing pressure, tin plating parameters, tin stripping and sand blasting and post-processing, the appearance quality, soldering performance and overall stability of the circuit board are further improved. The circuit board can meet the requirements of various high-end electronic equipment for high performance and high reliability, and has a wide market application prospect.

[0020] Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and / or additional aspects and advantages of the application will become apparent and be readily understood by considering the following detailed description, from which the above-mentioned and other aspects, advantages and novel features of the application will become readily apparent, especially when considered in connection with the drawings in which: Figure 1 A flow chart of a method for manufacturing a circuit board with partial electro-nickel-gold pads according to an embodiment of the present application; Figure 2 A structural schematic diagram of a method for manufacturing a circuit board with partial electro-nickel-gold pads according to an embodiment of the present application.

[0022] Explanation of reference numerals: Copper layer 110; First dry film 210; pad preset pattern 220; Nickel-gold layer 310; Side wall surface 410; Second dry film 510; Tin layer 610; Outer layer circuit 810. DETAILED DESCRIPTION

[0023] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which the same or similar numerals indicate the same or similar elements or elements having the same or similar functions throughout the drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0024] In the description of the present application, it should be understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as a limitation of the present application. The device or element indicated is not necessarily constructed and operated in a particular orientation.

[0025] In the description of the present application, the meaning of several is one or more, and the meaning of multiple is two or more. Greater than, less than, more than, etc. are understood as not including the number, and above, below, etc. are understood as including the number. If it is described as first, second, etc. only for the purpose of distinguishing technical features, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features.

[0026] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be understood in a broad sense, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0027] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" 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 specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0028] In the field of printed circuit board manufacturing, there is a wide demand for circuit boards with local electro-nickel thick gold pads, which are often used in electronic devices with high requirements for pad connection reliability, solderability and other performance, such as high-end chip packaging substrates, precision instrument mainboards, etc.

[0029] The conventional method for manufacturing circuit boards with local electro-nickel thick gold pads generally includes the following steps: pre-process, such as basic operations such as cutting, drilling, copper plating, pad pattern making, electro-nickel gold plating, film stripping, outer layer circuit pattern making, outer layer etching, film stripping, and post-process, to produce the final circuit board.

[0030] However, the existing conventional manufacturing method, which first makes the pads and then makes the outer layer circuit, has a nickel and thick gold layer covering the surface of the pad site after electro-nickel gold plating, with a thickness significantly higher than that of the surrounding copper surface, resulting in a certain height difference between the pad site and the copper surface of the board. In this regard, when the outer layer pattern dry film is attached to make the outer layer circuit, especially at the connection site between the thick gold site and the copper surface of the board, the dry film is difficult to attach tightly due to the height difference, making it easy for etching chemicals to seep in along the gap at the connection site during outer layer negative film etching. Once the chemicals seep in, they will corrode the copper layer that is not effectively protected by the dry film, causing open circuit, notch and other abnormalities. These abnormalities not only seriously affect the appearance quality of the circuit board, such as causing uneven surface and plating damage, but more importantly, they have a great negative impact on the electrical performance of the circuit board, such as causing line conduction failure, thereby affecting the normal operation of the entire electronic device.

[0031] Currently, there are some improvement attempts in the industry to solve this problem, but most of them focus on optimizing the dry film attachment or improving the etching chemical formula, none of which addresses the core problem of the height conflict caused by the process flow of first plating nickel gold and then etching the circuit. Therefore, it is difficult to fundamentally solve the problems of low circuit processing yield and high reliability risk.

[0032] Therefore, as shown in Figure 1 and Figure 2 The circuit board manufacturing method for local electro-nickel gold pads proposed by the present application includes the following steps performed in sequence: S100, plate surface copper plating: a copper layer 110 of a preset thickness is electroplated on the surface of the substrate; S200, initial pad pattern making: after the plate surface copper plating, a first dry film 210 is pasted and exposure and development processing is performed in sequence to make a pad preset pattern 220 at a preset position of the copper layer 110; S300, pad nickel-gold plating: after the initial pad pattern making, nickel and gold are electroplated in sequence on the surface of the pad preset pattern 220 to form a nickel-gold layer 310 on the surface of the pad preset pattern 220; S400, first film stripping: after the pad nickel-gold plating, the surface first dry film 210 is stripped to expose the copper layer 110 and the nickel-gold layer 310 higher than the copper layer 110; S500, positive film processing: after the first film stripping, a second dry film 510 is pasted, positive film exposure and development processing are performed in sequence to expose the side wall surface 410 of the connection between the copper layer 110 and the nickel-gold layer 310; S600, tin plating processing: after the positive film processing, tin is electroplated on the side wall surface 410 to form a tin layer 610; S700, second film stripping: after the tin plating processing, the surface second dry film 510 is stripped to expose the copper layer 110 and the nickel-gold layer 310; S800, etching processing: after the second film stripping, the copper foil is removed by an alkaline etching solution to process an outer layer circuit 810; S900, tin stripping and sand blasting: after the etching processing, the tin layer 610 is stripped and the surface of the nickel-gold layer 310 is subjected to sand blasting processing; S1000, post-processing: after the tin stripping and sand blasting, a solder resist layer, a surface treatment process and a forming process are made in sequence to produce a circuit board.

[0033] To this end, by means of first plating copper, locally plating thick gold, then carrying out positive film etching and utilizing the tin plating layer 610 to protect the key side wall, the problem of dry film not being tightly attached due to high and low position difference and etching chemical solution penetrating in the traditional process is fundamentally solved, and the yield and reliability of the circuit board manufacturing are improved; specifically, first, the surface of the board is plated with copper, which provides a basic conductive layer for subsequent circuit and pad manufacturing, then the initial pad pattern is made, the position and shape of the pad are accurately determined, the subsequent pad nickel gold plating step forms a nickel gold layer 310, which gives the pad good oxidation resistance, solderability and other properties, meeting the high requirements of the pad in specific application scenarios, then, the surface dry film is removed in the once film removal step, exposing the copper layer 110 and the nickel gold layer 310 higher than the copper layer 110, preparing for subsequent processing, it is worth noting that the positive film processing is one of the key links of this method, by sequentially attaching the dry film, positive film exposure and development processing, the side wall surface 410 at the connection between the copper layer 110 and the nickel gold layer 310 is exposed, which can accurately locate the key area that needs to be protected, for this, the tin plating processing is carried out after the positive film processing, tin is plated on the side wall surface 410 to form a tin layer 610, which acts as an effective protective barrier to block the erosion of the etching chemical solution on the side wall at the connection between the copper layer 110 and the nickel gold layer 310 in the subsequent etching process, avoiding the problem of chemical solution penetrating and corroding the copper layer 110 due to the dry film attachment problem in the traditional process; finally, the surface dry film is removed in the twice film removal step, exposing the copper layer 110 and the nickel gold layer 310, cooperating with the subsequent etching processing step, the copper foil is removed with alkaline etching solution, and the outer layer circuit 810 is processed; further, on the basis of ensuring that the pad has good performance, the process sequence and protection mechanism are optimized, so that the circuit board produced not only has high reliability of the local electro-nickel plated pad, but also avoids abnormal processing of the outer layer circuit 810, improves the overall quality and performance of the circuit board, and can better meet the requirements of electronic equipment for high precision and high reliability of the circuit board, has stronger market competitiveness and wider application prospect.

[0034] Moreover, after etching processing, the tin layer 610 is removed, and the surface of the nickel gold layer 310 is subjected to sand blasting treatment, it can be understood that after etching processing, the tin layer 610 has completed its protection function, and removing the tin layer 610 can avoid unnecessary influence of the tin layer 610 on subsequent processes and the final performance of the circuit board. Further, sand blasting treatment of the surface of the nickel gold layer 310 can remove impurities, oxide layers and the like that may exist on the surface of the nickel gold layer 310, making the surface of the nickel gold layer 310 smoother and flatter, and improving the quality and performance of the nickel gold layer 310; at the same time, sand blasting treatment can also increase the roughness of the surface of the nickel gold layer 310, which is beneficial to subsequent processes such as welding, and improves the firmness and reliability of welding. In addition, this step helps to improve the overall appearance quality of the circuit board, making the circuit board more beautiful, and meeting the requirements of high-end electronic products for the appearance of the circuit board.

[0035] In addition, after the tin stripping sandblasting, the solder mask layer, the surface treatment process and the forming process are made in sequence to make the circuit board. The production of the solder mask layer can protect the circuit and pad on the circuit board, prevent the circuit from being affected by the external environment during use, such as oxidation, humidity, etc., and improve the reliability and service life of the circuit board. The surface treatment process can further improve the surface performance of the circuit board, such as improving the solderability and corrosion resistance, to ensure that the circuit board can work normally during subsequent welding and use. The forming process processes the circuit board into the final shape and size required by the design, meeting the installation and use requirements of different electronic devices. Through these post-processing steps, the circuit board can have complete functions and good performance, and the overall quality and market competitiveness of the circuit board can be improved.

[0036] Compared with the existing conventional dry film pressing pressure of 3.5kg, in some embodiments of the present application, the pressing pressure of the second dry film 510 in the positive film processing is 4.5kg. It should be noted that the close fitting degree of the second dry film 510 in the positive film processing is crucial for the subsequent process, and appropriate pressing pressure can ensure that the second dry film 510 is fully and uniformly attached to the board surface. In many actual tests, when the pressing pressure is 4.5kg, it can be tightly attached and prevent etching chemicals from penetrating into the gap between the second dry film 510 and the board surface.

[0037] Referring again to Figure 1 In some embodiments of the present application, the following steps are further included: S510, making a circuit pattern: in the positive film processing, after the positive film exposure and development processing, the outer layer circuit 810 pattern is formed on the surface of the copper layer 110. For this, in addition to the side wall surface 410 of the connection between the copper layer 110 and the nickel-gold layer 310 exposed after the positive film processing, the outer layer circuit 810 pattern can be accurately constructed on the surface of the copper layer 110, and the subsequent etching processing is cooperated to process the outer layer circuit 810, so that the circuit board can meet the use requirements of various electronic devices.

[0038] Referring again to Figure 1 In some embodiments of the present application, the following steps are further included: S520, making a standard pad pattern: in the positive processing, after the positive exposure and development processing, a standard pad pattern is made at the corresponding position of the pad preset pattern 220, and the pad preset pattern 220 has a single-side compensation value greater than or equal to 2 mils relative to the standard pad pattern. On the one hand, by changing the way of the pad shape in the positive film, the surface of the connection between the nickel-gold layer 310 and the copper layer 110 is better exposed, so that the side wall surface 410 of the connection between the copper layer 110 and the nickel-gold layer 310 is better processed in the positive processing, which can better cooperate with the subsequent tin plating processing to form a tin layer 610 on the side wall surface 410. On the other hand, the setting of the single-side compensation value ensures that the actual size of the finally formed pad can meet the design requirements, ensures that there is enough contact area between the pad and the pins of the electronic components, thereby improving the stability and reliability of the welding, and further ensuring the quality and performance of the circuit board. For example, the pad preset pattern 220 is circular or square. It can be understood that the circular and square are common pad shapes, and the circular pad has good stress distribution characteristics when welding, which can reduce the problems of pad cracking or false welding caused by stress concentration during the welding process, and improve the reliability of the welding; and the square pad has a regular shape, which is convenient for layout and wiring in circuit design, can more efficiently utilize the space of the circuit board, and realize more compact circuit design. In some embodiments of the present application, as shown in FIG. 2B, the pad preset pattern 220 and the standard pad pattern are both circular, and the diameter of the pad preset pattern 220 is greater than the diameter of the standard pad pattern by more than 2 mils. Figure 2

[0039] In some embodiments of the present application, in the tin plating processing, the tin plating parameters are 14ASF*14min. It should be noted that the main function of tin plating is to form a protective tin layer 610 on the side wall surface 410 of the copper layer 110 and the nickel-gold layer 310 to prevent the etching solution from penetrating in the subsequent etching process, thereby avoiding open circuit defects of the circuit. Compared with the conventional tin plating parameters of 14ASF*8min, the present application adopts a longer tin plating time of 14min, which can ensure the formation of a uniform, dense and appropriate thickness tin layer 610 on the side wall surface 410 in actual application, which is suitable for the tin plating processing of the side wall surface 410 of the relatively thicker nickel-gold layer 310 relative to the copper layer 110.

[0040] ​The circuit board according to the embodiment of the present application is manufactured by the circuit board manufacturing method of the local electro-nickel gold pad according to the embodiment of the present application. Since the copper plating and pad nickel gold plating are adopted first, and then the optimized process steps such as positive film processing, tin plating protection, positive film etching, etc. are adopted, the circuit board effectively solves the problem of seepage of plating water caused by the height difference between the pad and the copper surface in the traditional manufacturing method, improves the electrical performance and reliability of the circuit board, and reduces the occurrence of defects such as open circuit and gap; at the same time, through reasonable process parameter setting and additional processing steps such as specific film pressing pressure, tin plating parameters, tin stripping sand blasting and post-processing, etc., the appearance quality, soldering performance and overall stability of the circuit board are further improved. The circuit board can meet the requirements of various high-end electronic equipment on high performance and high reliability of the circuit board, and has a wide market application prospect.

[0041] Other configurations and operations of the circuit board according to the embodiment of the present application are known to those skilled in the art, and will not be described in detail here.

[0042] The above describes the embodiments of the present application in detail in combination with the drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge range of those skilled in the art without departing from the purpose of the present application.

Claims

1. A method for fabricating a circuit board with partial nickel-gold solder pads, characterized in that, Includes the following steps: Copper plating on the board surface: Electroplating a copper layer of a predetermined thickness on the surface of the substrate; Creating the initial pad pattern: After copper plating on the board surface, the initial pad pattern is created at the predetermined position of the copper layer by sequentially applying dry film and exposure and development. Nickel-gold plating of pads: After creating the initial pad pattern, nickel and gold are electroplated sequentially on the surface of the pad pattern to form a nickel-gold layer on the surface of the pad pattern. One-time film removal: After nickel-gold plating on the pads, the surface dry film is removed to expose the copper layer and the nickel-gold layer above the copper layer; Positive film processing: After one stripping, the film is sequentially processed by applying dry film, positive film exposure and development to expose the sidewall surface at the junction of the copper layer and the nickel-gold layer; Tin plating: After the positive sheet is processed, tin is electroplated on the sidewall surface to form a tin layer; Secondary film removal: After tin plating, the surface dry film is removed to expose the copper layer and the nickel-gold layer; Etching process: After the second stripping, the copper foil is removed with an alkaline etching solution to process the outer layer circuitry.

2. The method for fabricating a circuit board with partial nickel-gold solder pads according to claim 1, characterized in that: In the positive film processing, the pressing pressure on the dry film is 4.5 kg.

3. The method for fabricating a circuit board with partial nickel-gold solder pads according to claim 1, characterized in that: It also includes the following steps: Creating circuit patterns: In positive film processing, after positive film exposure and development, an outer circuit pattern is formed on the surface of the copper layer.

4. The method for fabricating a circuit board with partial nickel-gold solder pads according to claim 1, characterized in that: The preset pattern of the solder pad is either circular or square.

5. The method for fabricating a circuit board with partial nickel-gold solder pads according to claim 4, characterized in that: It also includes the following steps: Creating standard pad patterns: In positive film processing, after positive film exposure and development, standard pad patterns are created at the corresponding positions of the preset pad patterns. The preset pad patterns have a single-sided compensation value of greater than or equal to 2mil relative to the standard pad patterns.

6. The method for fabricating a circuit board with partial nickel-gold solder pads according to claim 5, characterized in that: Both the preset pad pattern and the standard pad pattern are circular, and the diameter of the preset pad pattern is more than 2 mil larger than the diameter of the standard pad pattern.

7. The method for fabricating a circuit board with partial nickel-gold solder pads according to any one of claims 1 to 6, characterized in that: In the tin plating process, the tin plating parameters are 14ASF*14min.

8. The method for fabricating a circuit board with partial nickel-gold solder pads according to claim 1, characterized in that: It also includes the following steps: Tin removal and sandblasting: After etching, the tin layer is removed, and then the surface of the nickel-gold layer is sandblasted.

9. The method for fabricating a circuit board with partial nickel-gold solder pads according to claim 8, characterized in that: It also includes the following steps: Post-processing: After desoldering and sandblasting, solder mask, surface treatment and forming processes are carried out in sequence to produce the circuit board.

10. A circuit board, characterized in that: The circuit board is manufactured using the method of fabricating a partial nickel-gold solder pad as described in any one of claims 1 to 9.

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