Method for manufacturing solder mask layer of circuit board, method for surface treatment of circuit board and circuit board

Abstract

The present application is applicable to the technical field of circuit board manufacturing, and proposes a method for manufacturing a circuit board solder mask, including: providing a circuit board, on which a first solder pad and a second solder pad adjacent and spaced apart are provided; printing a first solder mask on the surface of the circuit board; making a first window portion on the first solder mask, with part of the first solder pad exposed in the first window portion to form a first solder mask window pad, and part of the second solder pad exposed in the first window portion to form a second solder mask window pad; the edge line of the first window portion includes a first curved extension section, and the first curved extension section is provided between the first solder mask window pad and the second solder mask window pad. The present application also proposes a circuit board surface treatment method and a circuit board. The present application improves the problem of short circuit of adjacent pads caused by plating caused by solder mask side erosion.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board manufacturing, and in particular to a method for manufacturing a solder mask layer of a circuit board, a circuit board surface treatment method and a circuit board. Background Art

[0002] At present, after making solder mask, some circuit boards need to perform surface treatment on the pads (PAD) in the solder mask opening to make a gold layer on the pads. For pads with smaller spacing in the solder mask opening, for example, the spacing between adjacent pads is less than 0.1mm, due to the side etching of the solder mask, the liquid is easy to remain at the side etching position during surface treatment, and the residual liquid grows along the side etching, resulting in gold infiltration and short circuit of adjacent pads.

[0003] Please refer to Figures 1 to 3 , Figure 1 Design drawings of solder mask openings and solder mask opening pads on circuit boards. Figure 2 The figure is a schematic diagram of the solder mask window deviation. Under normal circumstances, there is always a certain offset between the actual solder mask window and the theoretical solder mask window, resulting in a difference between the spacing H2 between the solder mask window pads B, C and the solder mask window and the theoretical window spacing. Assuming that H2 = 20um in the data design, when the deviation is serious and causes H2 < 10um, the gap between the solder mask window pad B and the solder mask window is easy to hide the solution, starting from the solder mask window pad B along the solder mask side erosion position, resulting in a short circuit between the solder mask window pad B and the solder mask window pad A. Figure 3 The area shown in III is the area of ​​solder resist side erosion and permeation.

[0004] For the problem of solder resist side erosion and plating, there are currently several solutions in the industry:

[0005] The first method: The ink at the side erosion position of the solder mask is carbonized and absorbed by laser drilling. After the ink at the side erosion position is cleaned, the solution cannot be hidden, so no plating will occur. However, this solution adds the laser drilling process. When the laser and the solder mask are seriously misaligned, laser drilling may cause damage to the copper surface and cause quality defects.

[0006] The second method: by increasing the size of the solder mask window, the position of the solder mask side erosion is moved away from the solder mask window pad, so as to avoid the solder mask side erosion causing gold penetration in small-pitch pads due to the hidden solution. However, the size of the solder mask window pad is usually determined by the size of the solder mask window. Under the premise of strict requirements on the pad size, the size of the solder mask window cannot be changed. Summary of the invention

[0007] In view of this, the present application provides a method for manufacturing a solder mask layer of a circuit board, a surface treatment method of a circuit board, and a circuit board, which can improve the problem of short circuit between adjacent pads caused by plating caused by solder mask side erosion.

[0008] The first aspect of the present application provides a method for manufacturing a solder mask layer of a circuit board, comprising:

[0009] Providing a circuit board, on which a first soldering pad and a second soldering pad are provided that are adjacent and spaced apart;

[0010] Printing a first solder mask on the surface of the circuit board;

[0011] A first window portion is made on the first solder resist layer, a portion of the first solder pad is exposed in the first window portion to form a first solder resist window pad, and a portion of the second solder pad is exposed in the first window portion to form a second solder resist window pad; the edge line of the first window portion includes a first curved extension section, and the first curved extension section is arranged between the first solder resist window pad and the second solder resist window pad.

[0012] In one embodiment, the first window portion includes a main body and a curved portion, the first curved extension section is the edge of the curved portion, the main body is rectangular and has a length of L1 and a width of W1; the first solder-proof window pad has a length of L2 and a width of W2, the second solder-proof window pad has a length of L3 and a width of W3, the second solder-proof window pad is spaced from the edge of the first window portion where the first curved extension section is located; the spacing between the first solder-proof window pad and the second solder-proof window pad is H1, and the first window portion satisfies the following conditions:

[0013] W1=L2; L1=L3+H1+W2.

[0014] In one embodiment, the curved portion protrudes toward the outside of the main body portion, and the curved extension section includes two first arcs with a radius of R1 and a second arc with a radius of R2, the two ends of the second arc are respectively connected to the two first arcs, the center of the first arc is set outside the first window portion and the center of the second arc is set inside the first window portion, and R1<R2.

[0015] In one embodiment, the distance between the ends of two first arcs connecting the main body is H4, and H4≥1 / 2*H1.

[0016] In one embodiment, the radii of the first arc and the second arc satisfy the following conditions:

[0017] 1 / 4*H1≤R1≤1 / 3*H1;

[0018] 1.0*H1≤R2≤1.5*H1.

[0019] In one embodiment, a third solder pad is further provided on the circuit board and a portion of the third solder pad is exposed in the first window portion to form a third solder-proof window pad; the third solder-proof window pad and the second solder-proof window pad are spaced apart and both extend along the first direction; in a second direction perpendicular to the first direction, the third solder-proof window pad and the second solder-proof window both have a gap with the edge line of the window portion; the edge line of the first window portion also includes a second curved extension section, and the second curved extension section is arranged between the first solder-proof window pad and the third solder-proof window pad.

[0020] In one embodiment, after forming the first window portion on the solder mask layer, the manufacturing method further includes:

[0021] Printing a second solder mask on the surface of the circuit board;

[0022] A second window portion is made on the second solder resist layer, wherein the edge line of the second window portion includes at least one second curved extension segment, and the second curved extension segment is arranged corresponding to the first curved extension segment.

[0023] In one embodiment, the size of the second window portion exceeds the size of the first window portion by 5 to 20 microns on one side; the mesh size of the printed screen of the first solder mask layer is greater than or equal to 43T, and the mesh size of the printed screen of the second solder mask layer is greater than or equal to 36T.

[0024] The second aspect of the present application provides a circuit board surface treatment method, comprising:

[0025] Making a solder mask on the circuit board, wherein the solder mask is made by the method for making a solder mask on the circuit board described in the first aspect;

[0026] The circuit board is surface treated to form a gold layer on the first solder mask window pad and the second solder mask window pad; the surface treatment method includes at least one of chemical nickel-gold, chemical nickel-palladium-gold, and electroplated gold.

[0027] A third aspect of the present application provides a circuit board, characterized in that the circuit board includes a solder mask layer manufactured by the method for manufacturing a solder mask layer of a circuit board according to the first aspect.

[0028] In the method for manufacturing a solder mask layer of a circuit board provided in the present application, a first window portion is formed on a first solder mask layer to form a first solder mask window pad and a second solder mask window pad, wherein a side of the first solder mask layer adjacent to the first solder mask window pad or the second solder mask window pad may hide liquid due to side erosion, that is, penetration plating occurs. The manufacturing method provided in the present application sets at least one first curved extension section on the edge of the first window portion, which can increase the edge length of the solder mask window as much as possible at a limited position, that is, extend the solder mask edge between the two pads, so as to increase the growth path of the metal after liquid penetration plating at the side erosion position, thereby reducing the short circuit between adjacent pads caused by penetration plating.

[0029] The above-mentioned method for manufacturing the solder mask layer of the circuit board and the circuit board can effectively alleviate the problem of short circuit between adjacent pads caused by plating caused by solder mask side erosion. Compared with the existing solutions, the above-mentioned manufacturing method does not need to increase the laser drilling process, avoids quality defects caused by laser drilling, and does not need to change the overall size of the solder mask opening and the size of the solder mask window pad. The above-mentioned manufacturing method can be used for pads with small pitches, has a simple process and low cost, and can ensure the quality of the circuit board.

[0030] The circuit board surface treatment method provided by the present application can extend the path between two adjacent pads by setting a first curved extension section at the edge of the first window portion of the first solder mask in the step of making the solder mask, thereby preventing the infiltration metal generated in the surface treatment step from connecting the two adjacent pads. Therefore, the circuit board surface treatment method can improve the problem of short circuit of small-pitch pads caused by solder mask side erosion and infiltration. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 It is a schematic diagram of the design of a circuit board at a solder mask opening in the prior art;

[0033] Figure 2 It is a schematic diagram of a circuit board in the prior art when the solder mask window is offset;

[0034] Figure 3 for Figure 2 A cross-sectional view of the circuit board shown along line II;

[0035] Figure 4 A flow chart of a method for manufacturing a solder mask layer of a circuit board provided in an embodiment of the present application;

[0036] Figure 5 A schematic diagram of a first pad, a second pad, and a third pad of a circuit board provided in an embodiment of the present application;

[0037] Figure 6 A schematic diagram of a circuit board after a solder mask window is opened provided in an embodiment of the present application;

[0038] Figure 7 for Figure 6 A schematic diagram of a bent portion in a first window portion of a circuit board shown;

[0039] Figure 8 for Figure 6 The schematic diagram of the circuit board shown in FIG. 1 after surface treatment;

[0040] Fig. 9 A schematic diagram of a first solder mask and a second solder mask provided in an embodiment of the present application;

[0041] Fig.10 A flow chart of a circuit board surface treatment method provided in an embodiment of the present application.

[0042] The meanings of the marks in the figure are:

[0043] 100. Circuit board; 10. First solder pad; 11. First solder mask window pad; 20. Second solder pad; 21. Second solder mask window pad; 30. Third solder pad; 31. Third solder mask window pad; 40. First solder mask layer; 41. First window portion; 401. First curved extension section; 402. Second curved extension section; 411. Main body; 412. Curved portion; 50. Second solder mask layer; 60. Metallization. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings, i.e., embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0046] It should also be noted that, in the embodiments of the present application, the same figure mark is used to represent the same component or the same part. For the same parts in the embodiments of the present application, the figure may only mark one of the parts or components as an example. It should be understood that the figure mark also applies to other identical parts or components.

[0047] In order to illustrate the technical solution of the present application, a description is given below with reference to specific drawings and embodiments.

[0048] The first embodiment of the present application provides a method for manufacturing a solder mask layer of a circuit board. Figures 4 to 6 The method for manufacturing the solder mask of a circuit board includes the following steps.

[0049] Step S110: providing a circuit board 100 , on which a first soldering pad 10 and a second soldering pad 20 are disposed which are adjacent and spaced apart.

[0050] Figure 5 The first pad 10 and the second pad 20 on the circuit board 100 are shown. The circuit board 100 is a circuit board on which the outer layer circuit has been manufactured. The circuit board 100 has completed the manufacturing of the previous process according to the normal process. The previous process includes cutting, inner layer circuit, AOI, lamination, drilling target, milling edge, drilling, outer layer pattern transfer, outer layer etching, AOI, but not limited to this, and some steps in the above process can be omitted or replaced. The circuit board 100 is, for example, a PCB board with 6 layers of circuits, but not limited to this.

[0051] Step S120 : printing a first solder mask layer 40 on the surface of the circuit board 100 .

[0052] The first solder resist layer 40 covers the surface of the circuit board 100 and covers the first pad 10 and the second pad 20 .

[0053] Step S130: A first window portion 41 is made on the first solder mask layer 40, a portion of the first solder pad 10 is exposed in the first window portion 41 to form a first solder mask window pad 11, and a portion of the second solder pad 20 is exposed in the first window portion 41 to form a second solder mask window pad 21; the edge line of the first window portion 41 includes a first curved extension section 401, and the first curved extension section 401 is arranged between the first solder mask window pad 11 and the second solder mask window pad 21.

[0054] Optionally, the second solder-resistant window pad 21 is spaced apart from the edge line where the first curved extension section 401 is located, and the first solder-resistant window pad 11 intersects with the edge line where the first curved extension section 401 is located.

[0055] The first opening portion 41 is formed on the first solder resist layer 40, and the specific steps may include exposure, development, and curing. Figure 6As shown, the edge line of the first window portion 41 includes a first curved extension section 401, and the second solder-proof window pad 21 is spaced apart from the edge line where the first curved extension section 401 is located. The first curved extension section 401 is arranged between the first solder-proof window pad 11 and the second solder-proof window pad 21, that is, the first curved extension section 401 is arranged on the side of the first solder-proof window pad 11 facing the second solder-proof window pad 21.

[0056] In the method for manufacturing the solder mask layer of the circuit board 100 provided in the present application, a first window portion 41 is formed on the first solder mask layer 40 to form a first solder mask window pad 11 and a second solder mask window pad 21, wherein the side of the first solder mask layer 40 adjacent to the first solder mask window pad 11 or the second solder mask window pad 21 may hide liquid due to side erosion, that is, plating occurs. The manufacturing method provided in the present application sets at least one first curved extension section 401 on the edge of the first window portion 41, which can increase the edge length of the solder mask window as much as possible at a limited position, that is, extend the solder mask edge between the two pads, so as to increase the growth path of the metal after liquid plating at the side erosion position, thereby reducing the short circuit between adjacent pads caused by plating.

[0057] The above-mentioned manufacturing method can effectively alleviate the problem of adjacent pads short-circuited due to the infiltration plating caused by solder mask lateral erosion. Compared with the existing solutions, the above-mentioned manufacturing method does not need to increase the process of laser drilling, avoids the quality defects caused by laser drilling, and does not need to change the overall size of the solder mask opening and the size of the solder mask opening pad. The above-mentioned manufacturing method can be used for pads with small pitches, with simple procedures and low costs, and can ensure the quality of the circuit board 100. The spacing between the first solder mask opening pad 11 and the second solder mask opening pad 21 can be less than 0.1 mm. Of course, the above-mentioned method is also applicable to pads with medium and large pitches.

[0058] Please refer to Figure 6 , Figure 7 In one embodiment, the first window portion 41 includes a main body portion 411 and a bent portion 412, the first bent extension section 401 is the edge line of the bent portion 412, the main body portion 411 is rectangular and has a length of L1 and a width of W1; the first solder mask window pad 11 has a length of L2 and a width of W2, and the second solder mask window pad 21 has a length of L3 and a width of W3; the spacing between the first solder mask window pad 11 and the second solder mask window pad 21 is H1, and the first window portion 41 satisfies the following conditions:

[0059] W1=L2; L1=L3+H1+W2.

[0060] The length L1 of the first window portion 41 determines the width W2 of the first solder-resistant window pad 11 and the length L3 of the second solder-resistant window pad 21. The width W1 of the first window portion 41 is equal to the length L2 of the first solder-resistant window pad 11. The distance between the second solder-resistant window pad 21 and the first solder-resistant window pad 11 is H1, and the distance between the second solder-resistant window pad 21 and the edge of the first window portion 41 is H2.

[0061] In one embodiment, the curved portion 412 protrudes toward the outside of the main body 411, and the curved extension section includes two first arcs with a radius of R1 and a second arc with a radius of R2, the two ends of the second arc are respectively connected to the two first arcs, the center of the first arc is set outside the first window portion 41 and the center of the second arc is set inside the first window portion 41, and R1 < R2. Please also refer to 8. After the subsequent surface treatment steps, a gold layer is formed on the first solder mask window pad 11 and the second solder mask window pad 21, respectively, and the edge of the first solder mask window pad 11 and the first window portion 41, and the edge of the second solder mask window pad 21 and the first window portion 41 form a plated metal 60. The plated metal 60 is difficult to extend along the first curved extension section 401, thereby preventing the short circuit between the first solder mask window pad 11 and the second solder mask window pad 21 caused by the plated metal 60.

[0062] This embodiment provides a specific structure of a bent portion 412. By adopting the above technical solution, the plated metal 60 caused by solder mask side erosion is difficult to extend to the entire bent portion 412, thereby preventing the second solder mask window pad 21 from short-circuiting with the first solder mask window pad 11. Since R1 < R2, the above-mentioned bent portion 412 can increase the length of the second arc within a limited space, and extend the edge line between the first solder mask window pad 11 and the second solder mask window pad 21 as much as possible.

[0063] It can be understood that the shapes of the curved portion 412 and the first curved extension segment 401 are not limited thereto. For example, the curved portion 412 may also be wavy or in other shapes.

[0064] In one embodiment, the distance between the ends of the two first arcs connecting the main body 411 is H4, where H4≥1 / 2*H1, so as to prevent the metal from growing along the undercut edge and being directly connected together.

[0065] In one embodiment, the radii of the first arc and the second arc satisfy the following conditions:

[0066] 1 / 4*H1≤R1≤1 / 3*H1;

[0067] 1.0*H1≤R2≤1.5*H1.

[0068] H1 is the distance between adjacent pads where plating may occur. If space permits, the length of R2 should be increased as much as possible to reduce the risk of plating. It is understandable that in actual production, the design of solder mask patterns will also be limited by the size of other surrounding windows or pads. Comprehensive considerations should be made to increase the length of the solder mask window edge line as much as possible in limited locations.

[0069] Please refer to Figure 5 , Figure 6 In one embodiment, a third solder pad 30 is further provided on the circuit board 100 and part of the third solder pad 30 is exposed in the first window portion 41 to form a third solder-proof window pad 31; the third solder-proof window pad 31 is spaced apart from the second solder-proof window pad 21 and both extend along the first direction; the spacing between the second solder-proof window pad 21, the third solder-proof window pad 31 and the first solder-proof window pad 11 is equal and is H1; in a second direction perpendicular to the first direction, there is a gap H2 between the second solder-proof window pad 21 and the edge of the first window portion 41, and there is a gap H3 between the third solder-proof window pad 31 and the edge of the first window portion 41; optionally, H2=H3. The edge of the first window portion 41 also includes a second curved extension section 402, and the second curved extension section 402 is provided between the first solder-proof window pad 11 and the third solder-proof window pad 31.

[0070] In this way, the method provided in the present application can also prevent a short circuit from occurring between the third solder mask window pad 31 and the first solder mask window pad 11 due to plating.

[0071] Please refer to Figure 6 , Fig. 9 In one embodiment, after the first window portion 41 is formed on the solder mask layer, the manufacturing method further includes: printing a second solder mask layer 50 on the surface of the circuit board 100; forming a second window portion (not shown) on the second solder mask layer 50, and the edge line of the second window portion includes a third curved extension section (not shown), and the third curved extension section is arranged corresponding to the first curved extension section 401.

[0072] The larger the solder mask erosion is, the more liquid medicine can be stored, and the greater the probability of infiltration. The solder mask erosion will increase with the thickness of the solder mask layer. This solution adopts batch production when making solder mask, for example, the solder mask layer is made in two times. This embodiment makes the solder mask erosion smaller each time by making solder mask in batches, thereby reducing the overall erosion amount, thereby further reducing the short circuit between adjacent pads caused by infiltration. Fig. 9 As shown, the side erosion depth of the first solder mask layer 40 is D1, and the side erosion depth of the second solder mask layer 50 is D2. Compared with the method of manufacturing the solder mask layer once, the manufacturing method provided in this embodiment reduces the depth of the solder mask side erosion.

[0073] In one embodiment, the size of the second window portion exceeds the size of the first window portion 41 by 5 to 20 microns on one side; the mesh size of the printed screen of the first solder mask layer 40 is greater than or equal to 43T, and the mesh size of the printed screen of the second solder mask layer 50 is greater than or equal to 36T.

[0074] Specifically, first use a screen-printed solder mask ink with a mesh size greater than or equal to 43T, and after pre-curing, use the first solder mask exposure data to expose, develop, and cure, then use a screen-printed solder mask ink with a mesh size greater than or equal to 36T, and after pre-curing, use the second solder mask exposure data to expose, develop, and cure; the size of the second window portion exceeds the size of the first window portion 41 by 5 to 20 microns on one side, and H5 in the figure is the difference in the sizes of the two windows. In this way, the alignment deviation that may occur in the two solder mask productions can be avoided.

[0075] Please refer to Fig.10 The embodiment of the second aspect of the present application provides a circuit board surface treatment method, comprising:

[0076] Step S210 : making a solder mask layer on the circuit board 100 .

[0077] The solder resist layer is manufactured by the manufacturing method of the circuit board solder resist layer provided in the first aspect. Optionally, the solder resist layer is the first solder resist layer 40 in the above embodiment, or includes the first solder resist layer 40 and the second solder resist layer at the same time.

[0078] Step S220 : performing surface treatment on the circuit board 100 to form a gold layer on the first solder mask window pad 11 and the second solder mask window pad 21 .

[0079] The surface treatment method includes at least one of chemical nickel-gold, chemical nickel-palladium-gold and electroplated gold. The gold layer is used to prevent the pad from being oxidized and maintain good solderability.

[0080] The surface treatment method of the circuit board 100 provided in the present application can extend the path between two adjacent pads by setting a first curved extension section 401 at the edge of the first window portion 41 of the first solder mask 40 in the step of making the solder mask, thereby preventing the metal plating generated in the surface treatment step from connecting the two adjacent pads. Therefore, the surface treatment method of the circuit board 100 can improve the problem of short circuit of small-pitch pads caused by solder mask side erosion and plating.

[0081] After step S220 , the circuit board 100 may be subjected to post-processing including molding, testing, FQC, etc.

[0082] The embodiment of the third aspect of the present application proposes a circuit board 100, which includes a solder mask layer manufactured by the method for manufacturing the solder mask layer of the circuit board 100 of the first aspect.

[0083] like Figure 6 As shown, the solder mask layer is provided with a first window portion 41, the edge line of the first window portion 41 includes a first curved extension section 401, and the first curved extension section 401 is provided between the first solder mask window pad 11 and the second solder mask window pad 21. Other features of the solder mask layer can be referred to the manufacturing method of any embodiment of the first aspect, and will not be repeated here.

[0084] The circuit board 100 provided in the present application includes the above-mentioned solder mask layer, which can also improve the problem of short circuit of small-pitch pads caused by solder mask lateral erosion and permeation.

[0085] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for manufacturing a solder mask layer of a circuit board, characterized in that: include: Providing a circuit board, on which a first soldering pad and a second soldering pad are provided that are adjacent and spaced apart; Printing a first solder mask on the surface of the circuit board; A first window portion is made on the first solder resist layer, a portion of the first solder pad is exposed in the first window portion to form a first solder resist window pad, and a portion of the second solder pad is exposed in the first window portion to form a second solder resist window pad; the edge line of the first window portion includes a first curved extension section, and the first curved extension section is arranged between the first solder resist window pad and the second solder resist window pad.

2. The method for manufacturing a solder mask layer of a circuit board according to claim 1, wherein: The first window portion includes a main body and a curved portion, the first curved extension section is the edge of the curved portion, the main body is rectangular and has a length of L1 and a width of W1; the first solder mask window pad has a length of L2 and a width of W2, the second solder mask window pad has a length of L3 and a width of W3, the second solder mask window pad is spaced from the edge of the first window portion where the first curved extension section is located; the spacing between the first solder mask window pad and the second solder mask window pad is H1, and the first window portion meets the following conditions: W1=L2; L1=L3+H1+W2.

3. The method for manufacturing a solder mask layer of a circuit board according to claim 2, characterized in that: The curved portion protrudes toward the outside of the main body portion, and the curved extension section includes two first arcs with a radius of R1 and a second arc with a radius of R2, the two ends of the second arc are respectively connected to the two first arcs, the center of the first arc is set outside the first window portion and the center of the second arc is set inside the first window portion, and R1<R2.

4. The method for manufacturing a solder mask layer of a circuit board according to claim 3, characterized in that: The distance between the ends of the two first arcs connecting the main body is H4, and H4≥1 / 2*H1.

5. The method for manufacturing a solder mask layer of a circuit board according to claim 3, characterized in that: The radii of the first arc and the second arc satisfy the following conditions: 1 / 4*H1≤R1≤1 / 3*H1; 1.0*H1≤R2≤1.5*H1.

6. The method for manufacturing a solder mask layer of a circuit board according to claim 1, wherein: A third solder pad is also provided on the circuit board and part of the third solder pad is exposed in the first window portion to form a third solder-proof window pad; the third solder-proof window pad and the second solder-proof window pad are spaced apart and both extend along the first direction; in a second direction perpendicular to the first direction, there is a gap between the third solder-proof window pad and the second solder-proof window and the edge line of the window portion; the edge line of the first window portion also includes a second curved extension section, and the second curved extension section is provided between the first solder-proof window pad and the third solder-proof window pad.

7. The method for manufacturing a solder mask layer of a circuit board according to any one of claims 1 to 6, characterized in that: After forming the first window portion on the solder mask, the manufacturing method further comprises: Printing a second solder mask on the surface of the circuit board; A second window portion is made on the second solder resist layer, wherein the edge line of the second window portion includes a third curved extension segment, and the third curved extension segment is arranged corresponding to the first curved extension segment.

8. The method for manufacturing a solder mask layer of a circuit board according to claim 7, characterized in that: The size of the second window portion exceeds the size of the first window portion by 5 to 20 microns on one side; the mesh size of the printed screen of the first solder mask layer is greater than or equal to 43T, and the mesh size of the printed screen of the second solder mask layer is greater than or equal to 36T.

9. A circuit board surface treatment method, characterized in that: include: Making a solder mask on the circuit board, wherein the solder mask is made by the method for making a solder mask for a circuit board according to any one of claims 1 to 8; The circuit board is surface treated to form a gold layer on the first solder mask window pad and the second solder mask window pad; the surface treatment method includes at least one of chemical nickel-gold, chemical nickel-palladium-gold, and electroplated gold.

10. A circuit board, characterized in that: The circuit board includes a solder resist layer made by the method for making a solder resist layer of a circuit board according to any one of claims 1 to 8.

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