Manufacturing method of printed circuit board

Abstract

To provide a printed circuit board with low cost and high accuracy, and provide a manufacturing method of the same.SOLUTION: A manufacturing method of a printed circuit board comprises a step of forming a solder resist layer 130 for selectively coating a front surface of a printed board 100 having a printed wiring group 120 containing a land 124 on the front surface so that a front surface of all or one part of at least the land 124 is exposed. The step of forming the solder resist layer 130 includes: a first step of forming a first sub-solder resist layer 131 by inkjet printing; and a second step of forming a second sub-solder resist layer 132 by screen printing. In a plan view of the printed board 100, the first sub-solder resist layer 131 is formed around a circumference of the land 124, and the second sub-solder resist layer 132 is formed around a circumference of an edge part 131a that is an edge part of at least the first sub-solder resist layer 131, and is adjacent to the circumference of the land 124.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a printed wiring board including a step of forming a solder resist film. [Background technology]

[0002] A printed wiring board comprises a substrate and printed wiring provided on the substrate, the printed wiring including lands for forming a predetermined circuit pattern and mounting electronic components by soldering. In order to prevent short circuits and oxidation of the printed wiring, a solder resist layer made of insulating resin (solder resist) is further formed on the surface of the printed wiring board on which the printed wiring is formed, except for the areas corresponding to the lands. In other words, only the lands are exposed on the surface of the printed wiring board, and the other areas of the printed wiring and the surface of the printed board are covered with the solder resist.

[0003] In recent years, electronic components such as capacitors included in printed wiring boards have become smaller, and accordingly, there is a demand to reduce the size of the lands soldered to the electronic components. Therefore, it is required to form the solder resist layer precisely in the desired position and shape so that the solder resist layer does not overlap the lands and impede soldering when mounting the components.

[0004] A known method for forming a solder resist layer with high accuracy so that it does not overlap the lands is pattern formation using a photo development method, but the photo development method requires a large number of steps such as exposure processing and development processing, which results in high costs and long working hours. Therefore, Patent Document 1 proposes a technology for forming a solder resist layer by screen printing, which is lower cost.

[0005] The technology disclosed in Patent Document 1 forms a solder resist layer by screen printing and curing two types of resin materials (solder resist inks) with different viscosities. Specifically, the periphery of the lands is covered with a solder resist ink having a higher viscosity, while the entire printed wiring board is covered with a solder resist ink having a lower viscosity, with the aim of forming a solder resist layer with high accuracy at low cost. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7014744 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-mentioned conventional solder resist forming method, two types of meshes are used as screen printing plates according to the type of solder resist ink and the printing location, but a change of setup is required every time the plate is replaced, and cleaning is required after each use. In addition, in order to maintain the accuracy of the plate after use, it is necessary to store it in a place where the temperature and humidity are controlled, and in addition, since the plate is elastic, its quality gradually deteriorates with use, and the accuracy of the solder resist layer, which is the final product, deteriorates. In order to maintain the accuracy, the plate needs to be remade periodically, which leads to high costs.

[0008] SUMMARY OF THE PRESENT DISCLOSURE Therefore, a primary object of the present invention is to provide a method for manufacturing a printed wiring board, which is capable of producing a printed wiring board at low cost and with high accuracy. [Means for solving the problem]

[0009] The method for manufacturing a printed wiring board according to the present invention includes a step of forming a solder resist layer that selectively covers a surface of a printed circuit board having printed wiring including lands on its surface, so that at least all or a portion of the surface of the lands is exposed, and the step of forming the solder resist layer includes a first step of forming a first sub-solder resist layer by inkjet printing and a second step of forming a second sub-solder resist layer by screen printing, and in this method for manufacturing a printed wiring board, in a planar view of the printed circuit board, the first sub-solder resist layer is formed around the lands, and the second sub-solder resist layer is formed around at least an edge of the first sub-solder resist layer that is adjacent to the periphery of the lands. Effect of the Invention

[0010] According to the present invention, it is possible to obtain a low-cost, highly accurate printed wiring board.

[0011] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings. [Brief description of the drawings]

[0012] [Figure 1] 1 is a plan view showing a printed wiring board according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 1 is a flowchart illustrating a method for manufacturing a printed wiring board according to a first embodiment of the present invention. [Figure 4] 1(A) to 1(C) are cross-sectional views illustrating a method for manufacturing a printed circuit board of a printed wiring board according to a first embodiment of the present invention. [Diagram 5] 1(A) to 1(D) are cross-sectional views illustrating a method for manufacturing a printed wiring board according to a first embodiment of the present invention. [Figure 6]1(A) to 1(C) are plan views illustrating a method for manufacturing a printed wiring board according to a first embodiment of the present invention. [Figure 7] 1(A) to 1(F) are cross-sectional views showing examples of the structure of a laminate according to a first embodiment of the present invention. [Figure 8] 5(A) to 5(C) are cross-sectional views illustrating a method for manufacturing a printed wiring board according to a modified example of the first embodiment of the present invention. [Figure 9] 5(A) to 5(D) are cross-sectional views illustrating a method for manufacturing a printed wiring board according to a modified example of the first embodiment of the present invention. [Figure 10] FIG. 4 is a plan view showing a printed wiring board according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view taken along line XI-XI in FIG. [Figure 12] 5(A) to 5(D) are cross-sectional views illustrating a method for manufacturing a printed wiring board according to a second embodiment of the present invention. [Figure 13] 11(A) to 11(C) are plan views illustrating a method for manufacturing a printed wiring board according to a second embodiment of the present invention. [Figure 14] 13(A) to 13(C) are cross-sectional views illustrating a method for manufacturing a printed wiring board according to a modified example of the second embodiment of the present invention. [Figure 15] 13(A) to 13(D) are cross-sectional views illustrating a method for manufacturing a printed wiring board according to a modified example of the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A. First embodiment An example of a method for manufacturing a printed wiring board according to the first embodiment of the present invention will be described below.

[0014] 1. Printed wiring boards A printed wiring board 10, which is an example of a printed wiring board according to a first embodiment of the present invention, will be described. Fig. 1 is a plan view showing printed wiring board 10 according to the first embodiment of the present invention. Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1.

[0015] The printed wiring board 10 includes a printed circuit board 100 and a solder resist layer 130 provided on the printed circuit board 100 .

[0016] (Printed circuit board) The printed circuit board 100 includes a base material 110 and a printed wiring group 120 provided on the base material 110. The base material 110 can have various configurations as described below, but can be, for example, a glass epoxy board.

[0017] The printed wiring group 120 is a thin film layer of a conductive material that is processed to form a predetermined circuit pattern by means of etching or the like after being bonded to the surface of the base material 110. As the conductive material of the printed wiring group 120, for example, copper foil can be used.

[0018] A predetermined number of lands for soldering to electronic components are provided at arbitrary positions on each of the printed wirings constituting the printed wiring group 120. In this embodiment, as an example in which the configuration is simplified for the purpose of explanation, a land 124 is formed at an end of the second printed wiring 122 in the first printed wiring 121, the second printed wiring 122, and the third printed wiring 123 constituting the printed wiring group 120. The land 124 is shown as having a rectangular shape wider than the second printed wiring 122 in a plan view, but may have a circular shape or any other arbitrary shape.

[0019] (solder resist layer) The solder resist layer 130 is an insulating layer provided in the printed wiring board 10 so as to cover the entire surface of the printed circuit board 100 except for a portion of the printed circuit board 100 including the lands 124 and their surroundings.

[0020] The solder resist layer 130 has a first sub-solder resist layer 131 formed around the lands 124 in a plan view of the printed circuit board 100 (hereinafter, simply referred to as "plan view"), and a second sub-solder resist layer 132 formed around the periphery of the edge of the first sub-solder resist layer 131 on the side adjacent to the periphery of the lands 124. Details will be described below.

[0021] The first auxiliary solder resist layer 131 is an insulating layer having a rectangular frame shape in plan view, which is formed so as to surround the land 124 including a part of the second printed wiring 122 without any breaks. Specifically, the first auxiliary solder resist layer 131 has an opening 131x having a rectangular shape in plan view at the center of the outer shape of the rectangular shape in plan view, and the land 124 is disposed within the opening 131x. In the first auxiliary solder resist layer 131, an edge 131a of the opening 131x, which is an inner edge adjacent to the periphery of the land 124, is formed to be separated from the edge 124a of the land 124 by a predetermined distance G. That is, the first auxiliary solder resist layer 131 is formed so as not to overlap or contact the land 124. The dimension of the distance G can be any value depending on the shape and dimensions of the land 124, but is preferably in the range of 50 μm to 200 μm, for example.

[0022] In the first sub-solder resist layer 131, the distance between the edge 131a and the edge 131b, i.e., the dimension of the width W1 of the frame shape, can be any value depending on the circuit pattern of the printed wiring group 120, but it is preferable that it is in the range of 100 μm or more and 300 μm, for example.

[0023] The shape of the opening 131x preferably corresponds to the shape of the land 124. That is, when the land 124 is circular or has any other shape, the opening 131x preferably has a similar shape to the land 124.

[0024] The thickness T1 of the first solder resist sub-layer 131 can be any value depending on the design conditions of the printed wiring board 10, but is preferably in the range of 5 μm to 20 μm, for example.

[0025] The second auxiliary solder resist layer 132 is an insulating layer formed to surround from the outside the periphery of the exposed portion of the printed circuit board 100 including the lands 124, which is surrounded by the first auxiliary solder resist layer 131, and to cover all remaining portions of the printed circuit board 100. Specifically, the second auxiliary solder resist layer 132 has an opening 132x that is rectangular in plan view corresponding to the position of the first auxiliary solder resist layer 131, and is formed so that the opening 131x of the first auxiliary solder resist layer 131 is disposed within the opening 132x. An edge 132a of the opening 132x, which is the inner edge of the second auxiliary solder resist layer 132, is formed to be located outside the opening 131x of the first auxiliary solder resist layer 131 and inside the edge 131b, which is the outer edge of the first auxiliary solder resist layer 131.

[0026] As a result, the solder resist layer 130 has an overlapping region 130a that is a region formed by overlapping the second solder resist sub-layer 132 on the first solder resist sub-layer 131. The dimension L of the overlapping region 130a in a plan view can be any value depending on the shape and dimensions of the first solder resist sub-layer 131 and the circuit pattern of the printed wiring group 120, but is preferably in the range of 50 μm to 200 μm, for example.

[0027] The shape of the opening 132x preferably corresponds to the shape of the opening 131x. That is, when the opening 131x is circular or has any other shape, it is preferable that the opening 132x also has a similar shape.

[0028] The thickness T2 of the second sub-solder resist layer 132 can be any value depending on the design conditions of the printed wiring board 10, but is preferably in the range of 5 μm to 30 μm, for example. Furthermore, it is preferable that the thickness T2 of the second sub-solder resist layer 132 and the thickness T1 of the first sub-solder resist layer 131 have a relationship of T2>T1.

[0029] In addition, the solder resist layer 130 is formed on the printed wiring board 10 having one land 124 as a land, and has an opening 131x in the first sub-solder resist layer 131 that exposes the land 124, but the solder resist layer may selectively cover so that all or part of the surface of the land included in the printed wiring is exposed, depending on various circuit patterns of the printed wiring on the printed wiring board.

[0030] 2. Manufacturing method of printed wiring board A printed wiring board 10, which is an example of a printed wiring board according to a first embodiment of the present invention, will be described. Fig. 3 is a diagram showing a flowchart illustrating a method for manufacturing the printed wiring board 10 according to the first embodiment of the present invention. Figs. 4 and 5 are schematic cross-sectional views showing the state of the printed wiring board 10 in the process shown in the flowchart of Fig. 3, and are cross-sectional views corresponding to the cross-sectional view of line II-II in Fig. 2. Fig. 6 is a plan view showing the state of the printed wiring board 10 in the process shown in the flowchart of Fig. 3.

[0031] (Printed circuit board manufacturing) First, a laminate 200 is prepared in which a copper foil layer 112, which serves as a base for a printed wiring group 120, is bonded to the surface of a base material 110 (step S001). FIG. 7(A) shows a cross section of the laminate 200 prepared in step S001. In the laminate 200, the base material 110 is configured by impregnating a glass cloth with an epoxy resin. In this way, the printed circuit board 100 is obtained as a glass epoxy board. In this case, it is preferable that the thickness of the base material 110 is 0.1 mm or more and 2.0 mm or less, and the thickness of the copper foil layer 112 is 18 μm or more and 70 μm or less.

[0032] The laminate 200 may have the following structure. That is, as shown in FIG. 7B, the base material 110 may be made of paper impregnated with phenol resin. In this way, the printed circuit board 100 is obtained as a paper phenol board. In this case, the thickness of the base material 110 is preferably 0.8 mm or more and 2.0 mm or less, and the thickness of the copper foil layer 112 is preferably 35 μm or more and 70 μm or less.

[0033] Similarly, as shown in Fig. 7(C), the substrate 110 may be configured by bonding a laminate material 111b of glass cloth to both sides of a core material 111a of paper, and impregnating both materials with epoxy resin. In this way, the printed circuit board 100 is obtained as a composite substrate-epoxy substrate. In this case, the thickness of the substrate 110 is preferably 0.8 mm or more and 1.6 mm or less, and the thickness of the copper foil layer 112 is preferably 35 µm.

[0034] Similarly, as shown in Fig. 7(D), the base material 110 may be configured by bonding a laminate material 111b of glass cloth to both sides of a core material 111a of glass nonwoven fabric, and impregnating both materials with epoxy resin. In this way, the printed circuit board 100 is obtained as a glass composite board. In this case, it is preferable that the thickness of the base material 110 is 0.8 mm or more and 1.6 mm or less, and the thickness of the copper foil layer 112 is 18 μm or more and 70 μm or less.

[0035] Similarly, as shown in FIG. 7(E), the base material 110 may be configured such that a laminate material 111b, which is an insulating layer having excellent thermal conductivity and is a mixture of epoxy resin and filler, is bonded to the surface of a core material 111a, which is an aluminum plate, on the side where the copper foil layer 112 is bonded. As the filler, any one of metal oxide, metal hydroxide, and glass cloth is used. In this way, the printed circuit board 100 is obtained as an aluminum-based board. In this case, it is preferable that the thickness of the core material 111a is 1.0 mm or more and 3.0 mm or less, the thickness of the laminate material 111b is 80 μm or more and 120 μm or less, and the thickness of the copper foil layer 112 is 18 μm or more and 105 μm or less.

[0036] Similarly, as shown in Fig. 7(F), the base material 110 may be configured by bonding a laminate material 111b, which is an insulating layer having a similar structure to the insulating layer in Fig. 7(E), to the surface of a core material 111a, which is a copper plate, on the side to which the copper foil layer 112 is bonded. In this way, the printed circuit board 100 is obtained as a copper-based board. In this case, it is preferable that the thickness of the core material 111a is 1.0 mm or more and 1.5 mm or less, the thickness of the laminate material 111b is 120 μm, and the thickness of the copper foil layer 112 is 35 μm or more and 105 μm or less.

[0037] Next, a mask having a planar shape corresponding to the circuit pattern of the printed wiring group 120 is prepared (step S002). When the printed wiring group 120 is obtained by a photography method, the mask is prepared as a film having the circuit pattern as an opening. When the printed wiring group 120 is obtained by a printing method, the mask is prepared as a screen plate having the circuit pattern as an opening. When the mask is applied directly to the laminate to obtain the printed wiring group 120, the mask is prepared by software, for example, as CAD data of the printing pattern.

[0038] Next, an etching resist layer having a circuit pattern is formed on the copper foil layer 112 using a mask (step S003). When the printed wiring group 120 is obtained by a photographic method, a mask is laminated in a state where the etching resist ink is uniformly applied on the copper foil layer 112, and unnecessary portions are removed from the applied etching resist ink through the steps of exposure and development. When the printed wiring group 120 is obtained by a printing method, a negative shape of the mask is formed on a screen plate on the copper foil layer 112, and the etching resist ink is formed on the copper foil layer 112 by screen printing. Also, a printer is used to print etching resist ink directly on the copper foil layer 112. Fig. 4(A) shows a state in which an etching resist layer 140 has been formed on the surface of the laminate 200 in step S003.

[0039] Next, the laminate 200 on which the etching resist layer 140 has been formed is etched to remove the copper foil layer 112 except for the portion covered by the etching resist layer 140 (step S004). As a result, the planar shape of the copper foil layer 112 forms a circuit pattern that reflects the planar shape of the etching resist layer 140. Fig. 4(B) shows a state in which the planar shape of the copper foil layer 112 forms a circuit pattern on the surface of the laminate 200 by the etching resist layer 140 in step S004.

[0040] Next, the etching resist layer 140 is removed from the laminate 200 by peeling it off with an ink remover (step S005). This results in the printed circuit board 100. Figures 4(C) and 6(A) show the state in which the printed circuit board 100 is obtained by removing the etching resist layer 140 from the laminate 200 in step S005.

[0041] (Formation of solder resist layer) Next, the solder resist layer 130 is formed on the printed circuit board 100 .

[0042] First, in a first step, the first sub-solder resist layer 131 is formed by inkjet printing around a part of the second printed wiring 122 of the printed wiring group 120 and the lands 124 (step S006).

[0043] 6(B), the first sub-solder resist layer 131 has a rectangular outer shape in plan view, has a rectangular opening 131x in plan view formed in the center, and the land 124 is arranged within the opening 131x. Specifically, using an inkjet printer to which the shape of the first sub-solder resist layer 131 has been input as CAD data, solder resist ink 301 is applied by inkjet printing as shown in FIG. 5(A), and then the solder resist ink 301 is cured with UV light and then thermally cured, thereby forming the first sub-solder resist layer 131.

[0044] In the above description, the first step is described as forming one first sub-solder resist layer 131 around land 124 for printed wiring board 10 having one land 124 as a land. However, the first step may be any step of selectively forming each of a plurality of first sub-solder resist layers corresponding to all or part of each of a plurality of lands according to the design of the printed wiring board.

[0045] The thickness T1 of the first sub-solder resist layer 131 can be any value depending on the design conditions of the printed wiring board 10, but is preferably in the range of 5 μm to 20 μm, for example. Moreover, it is preferable that the inkjet printing is performed in an environment with a temperature of 20° C. to 25° C. and a humidity of 30% to 70%.

[0046] By using inkjet printing to print the solder resist ink 301, the edge 131a of the opening 131x of the first sub-solder resist layer 131 can be formed with high precision while being separated from the edge 124a of the land 124 by a predetermined distance G without contacting or overlapping the surface of the land 124.

[0047] Furthermore, by using inkjet printing to print the solder resist ink 301, the coordinates of the printing position can be optically obtained by a CCD camera or the like for each production of the printed wiring board 10, and the position on the X-axis and Y-axis on the surface of the printed circuit board 100 can be corrected successively. Specifically, the recognition marks, lands 124, and other corners of specific locations of the printed wiring group 120 that have been previously formed when the printed wiring group 120 is formed are read, and the printing position is set based on the read positions.

[0048] As a result, even when the printed wiring board 10 is repeatedly manufactured, the cost required for replacing the plate as in other printing methods can be eliminated and the precision of the first sub-solder resist layer 131 can be kept uniform.

[0049] The solder resist ink 301 used for the first sub-solder resist layer 131 is a resin that is mainly made of acrylate resin and can be cured by both UV and heat, and preferably has a viscosity in the range of 10 mPa·s to 45 mPa·s. The solder resist ink 301 is preferably stored in a cool, dark place at a temperature of 0°C to 30°C.

[0050] The curing conditions of the solder resist ink 301 are preferably as follows for UV curing and thermal curing: 100 mJ / cm 2 More than 500mJ / cm 2 It is preferable to set the lamination light amount in the following range. For thermal curing, it is preferable to set the curing temperature at 150° C. and the exposure time in the range of 20 minutes to 70 minutes. Fig. 6(B) shows a state in which the first sub-solder resist layer 131 is formed on the printed circuit board 100 in step S006.

[0051] Next, in a second step, the second auxiliary solder resist layer 132 is formed on the printed circuit board 100 by screen printing (step S007).

[0052] The second auxiliary solder resist layer 132 is formed so as to surround from the outside the periphery of the exposed portion of the printed circuit board 100 including the lands 124, which is surrounded by the first auxiliary solder resist layer 131, and to cover all remaining portions of the printed circuit board 100. Specifically, as shown in FIG. 5B, a screen plate 300 is placed on the first auxiliary solder resist layer 131, and as shown in FIG. 5C, a squeegee (not shown) is pressed against the screen plate 300 in parallel with the printed circuit board 100, and solder resist ink 302 is printed so as to fill the screen openings 300x on the screen plate 300. Thereafter, as shown in FIG. 5D, the screen plate 300 is removed from the printed circuit board 100, and the solder resist ink 302 is cured to form the second auxiliary solder resist layer 132.

[0053] In the above description, the second step is described as forming one second sub-solder resist layer 132 around the exposed portion of the printed circuit board 100, including the land 124, for the printed wiring board 10 having one land 124 as a land. However, the second step may be any step that forms each of the multiple first sub-solder resist layers and a second sub-solder resist layer spanning the surface of the printed circuit board according to the design of the printed wiring board.

[0054] The thickness of the second sub-solder resist layer 132 can be any value depending on the design conditions of the printed wiring board 10, but is preferably in the range of 5 μm to 20 μm, for example. Furthermore, the thickness of the second sub-solder resist layer 132 is preferably greater than the thickness of the first sub-solder resist layer 131 formed earlier. This allows the first sub-solder resist layer 131 and the second sub-solder resist layer 132 to be formed by taking advantage of the advantages of their respective printing methods. Moreover, the screen printing is preferably performed in an environment with a temperature of 20° C. to 25° C. and a humidity of 30% to 70%.

[0055] When printing the solder resist ink 302 by screen printing, the alignment of the screen plate 300 can be performed as follows: That is, a work guide is installed on the printing machine to which the screen plate 300 is attached, and the printed circuit board 100 is brought into contact with the work guide during printing, whereby alignment is performed based on the assembly accuracy of the screen plate 300 and the work guide.

[0056] The alignment may be performed by providing a through-hole for alignment in the printed circuit board 100 and inserting a pin, the position of which is predetermined for combination with the screen plate 300, through the through-hole. Furthermore, the alignment may be performed by visually comparing the pattern of the screen plate 300 with the printed wiring group 120 of the printed circuit board 100.

[0057] The screen plate 300 is, for example, a gauze made of stainless steel, polyester, polyarylate, or the like, and has screen openings 300x formed in the portions other than the masking portions 300a that shield the first sub-solder resist layer 131. When printing is performed using the screen plate 300, a gap is provided between the screen plate 300 and the printed circuit board 100, and printing is performed on the printed circuit board 100 while pulling the screen plate 300.

[0058] The screen printing of the second sub-solder resist layer 132 has the advantage that it takes less time to print than inkjet printing when the printing area or the coating thickness is large. Furthermore, when the printing area is large, there is an advantage that the variation in the coating thickness is smaller than with inkjet printing.

[0059] The solder resist ink 302 used for the second sub-solder resist layer 132 can be either a UV curable resin containing acrylate resin as the main material or a thermosetting resin containing epoxy resin as the main material.

[0060] When a UV-curable resin is used as the solder resist ink 302, the viscosity is in the range of 70 dPa·s to 250 dPa·s. The curing condition of the solder resist ink 302 is 300 mJ / cm 2 More than 2500mJ / cm 2 It is preferable to set the integrated light amount within the following range.

[0061] When using a thermosetting resin as the solder resist ink 302, a bisphenol A type epoxy resin or a novolac type epoxy resin with a viscosity in the range of 150 dPa·s to 350 dPa·s is used. The curing conditions for the solder resist ink 302 are preferably a temporary curing at a curing temperature in the range of 70°C to 90°C for 8 minutes, followed by a main curing at a curing temperature of 150°C for 20 minutes to 70 minutes. The solder resist ink 302 is preferably stored in a cool, dark place at a temperature of 0°C to 30°C.

[0062] 6C shows a state in which the second sub-solder resist layer 132 is formed on the printed circuit board 100 in step S007. As shown in FIG 1, an edge 132a of an opening 132x which becomes an inner edge in the second sub-solder resist layer 132 is formed to be located outside the opening 131x of the first sub-solder resist layer 131 and inside an edge 131b which becomes an outer edge in the first sub-solder resist layer 131.

[0063] As a result, the completed solder resist layer 130 has an overlapping region 130a formed by the second solder resist sub-layer 132 overlapping the first solder resist sub-layer 131 from above.

[0064] Finally, external shape and hole processing and surface finishing are performed to complete the printed wiring board 10 (step S008). In order to clean the lands 124 and their surrounding surfaces on which the solder resist layer 130 is not formed, degreasing and rust removal are performed using, for example, acid.

[0065] The manufacturing method for the printed wiring board 10 according to the first embodiment of the present invention forms the solder resist layer 130 from two layers, namely, a first sub-solder resist layer 131 formed around the land 124 through the opening 131x, and a second sub-solder resist layer 132 formed around the edge 131a of the first sub-solder resist layer 131 adjacent to the periphery of the land 124 through the opening 132x, and forms the first sub-solder resist layer 131 by inkjet printing and the second sub-solder resist layer 132 by screen printing, thereby achieving the following effects.

[0066] That is, the first sub-solder resist layer 131 can be formed with high accuracy by using inkjet printing, while the second sub-solder resist layer 132, which does not require as high accuracy as the first sub-solder resist layer 131 and has a larger surface area and layer thickness, can be formed by screen printing in a shorter time and at a lower cost than the first sub-solder resist layer 131. Furthermore, by forming the first sub-solder resist layer 131 by using inkjet printing, there is no need to replace the plate as in other printing methods, so that uniform accuracy can be maintained at low cost even when the printed wiring board 10 is repeatedly manufactured.

[0067] Therefore, the solder resist layer 130 can be obtained with high precision and at low cost.

[0068] In the method for manufacturing printed wiring board 10 according to the first embodiment of the present invention, overlapping region 130a of solder resist layer 130 is formed such that second sub-solder resist layer 132 overlaps first sub-solder resist layer 131, thereby allowing screen printing to be performed after inkjet printing. This allows the periphery of lands 124 to be exposed with higher accuracy in advance, thereby compensating for variations in accuracy due to screen printing, and allows solder resist layer 130 to be formed efficiently.

[0069] 3. Modification of the First Embodiment In the method for manufacturing printed wiring board 10 according to the first embodiment, overlapping region 130a of solder resist layer 130 may be formed such that first sub-solder resist layer 131 overlaps second sub-solder resist layer 132. In this case, the order of the step of forming first sub-solder resist layer 131 by inkjet printing (step S006) and the step of forming second sub-solder resist layer 132 by screen printing (step S007) is reversed in the flowchart for explaining the method for manufacturing a printed wiring board shown in FIG.

[0070] Specifically, the completed printed circuit board 100 shown in Fig. 9(A) is prepared. Next, as shown in Fig. 9(B), a second sub-solder resist layer 132 is formed by screen printing so as to cover all remaining portions of the prepared printed circuit board 100, leaving openings 132x. The openings 132x are openings that expose the surface of the printed circuit board 100, including the lands 124, which will be inside the openings 131x of the first sub-solder resist layer 131 to be formed later.

[0071] 8(A) to 8(C), the specific steps of screen printing are performed by printing and curing solder resist ink 302 using a screen plate 300. Note that the details of the steps shown in each figure, the material of the solder resist ink 302, the curing conditions, etc. are the same as those in the embodiment described above with reference to FIG. 5, and therefore detailed description thereof will be omitted.

[0072] Next, as shown in Fig. 9(C), the first sub-solder resist layer 131 is formed on the printed circuit board 100 on which the second sub-solder resist layer 132 has been formed by inkjet printing of a solder resist ink 302. The first sub-solder resist layer 131 has a rectangular outer shape in a plan view and a rectangular opening 131x in a plan view at the center, and the opening 131x is formed so that its edge 131a does not overlap the surface of the land 124 and is separated from the edge 124a of the land 124 by a predetermined distance. Note that the specific details of the inkjet printing process, the material of the solder resist ink 302, the curing conditions, etc. are the same as those in the above embodiment described with reference to Fig. 5, and detailed description thereof will be omitted.

[0073] By forming the overlapping region 130a of the solder resist layer 130 so that the first sub-solder resist layer 131 overlaps the second sub-solder resist layer 132, inkjet printing is performed after screen printing, thereby precisely compensating for variations in accuracy due to screen printing, and the periphery of the land 124 can be exposed with greater precision.

[0074] B. Second embodiment Next, an example of a method for manufacturing a printed wiring board according to a second embodiment of the present invention will be described.

[0075] 1. Printed wiring boards A printed wiring board 10A, which is an example of a printed wiring board according to a second embodiment of the present invention, will be described. Fig. 10 is a plan view showing the printed wiring board 10A according to the second embodiment of the present invention. Fig. 11 is a schematic cross-sectional view taken along line XI-XI in Fig. 10. However, the same reference numerals are used for configurations that are the same as or correspond to those in Figs. 1 to 9, and detailed descriptions thereof will be omitted.

[0076] The printed wiring board 10A according to the second embodiment differs from the printed wiring board 10 according to the first embodiment in that a first sub-solder resist layer 131 is formed so as to cover a portion of the surface of the second printed wiring 122.

[0077] (Printed circuit board) The printed circuit board 100 includes a base material 110 and a printed wiring group 120 provided on the base material 110. The printed wiring group 120 is a thin film layer of a conductive material that is bonded to the surface of the base material 110 and then processed by a means such as etching to form a predetermined circuit pattern.

[0078] A predetermined number of lands for soldering to electronic components are provided at arbitrary positions on each of the printed wirings constituting the printed wiring group 120. In this embodiment, as an example in which the configuration is simplified for the purpose of explanation, a land 124 is formed at an end of the second printed wiring 122 in the first printed wiring 121, the second printed wiring 122, and the third printed wiring 123 constituting the printed wiring group 120. The land 124 is shown as having a rectangular shape wider than the second printed wiring 122 in a plan view, but may have a circular shape or any other arbitrary shape.

[0079] (solder resist layer) The solder resist layer 130 is an insulating layer provided in the printed wiring board 10A so as to cover the entire surface of the printed circuit board 100 except for a portion of the lands 124 and their surfaces.

[0080] The solder resist layer 130 has a first sub-solder resist layer 131 formed so as to expose a part of the land 124 in a plan view of the printed circuit board 100 (hereinafter, abbreviated as "plan view"), and a second sub-solder resist layer 132 formed around the edge of the first sub-solder resist layer 131 on the side opposite to the exposed area of ​​the land 124. Details will be described below.

[0081] The first sub-solder resist layer 131 is an insulating layer having a rectangular frame shape in plan view, which is formed so as to expose a part of the surface of the land 124 including a part of the second printed wiring 122. Specifically, the first sub-solder resist layer 131 has an opening 131x having a rectangular shape in plan view at the center of its rectangular shape in plan view, and is formed so that the surface of the land 124 is exposed through the opening 131x.

[0082] In the first sub-solder resist layer 131, the distance between the edge 131a and the edge 131b, i.e., the dimension of the width W1 of the frame shape, can be any value depending on the circuit pattern of the printed wiring group 120, but it is preferable that it is in the range of 100 μm or more and 300 μm, for example.

[0083] The shape of the opening 131x preferably corresponds to the shape of the land 124. That is, when the land 124 is circular or has any other shape, the opening 131x preferably has a similar shape to the land 124.

[0084] The thickness T3 of the first sub-solder resist layer 131 can be any value depending on the design conditions of the printed wiring board 10, but is preferably in the range of 5 μm to 20 μm, for example.

[0085] The second auxiliary solder resist layer 132 is an insulating layer formed to surround from the outside the periphery of the exposed portion of the printed circuit board 100 including the lands 124, which is surrounded by the first auxiliary solder resist layer 131, and to cover all remaining portions of the printed circuit board 100. Specifically, the second auxiliary solder resist layer 132 has an opening 132x that is rectangular in plan view corresponding to the position of the first auxiliary solder resist layer 131, and is formed so that the opening 131x of the first auxiliary solder resist layer 131 is disposed within the opening 132x. An edge 132a of the opening 132x, which is the inner edge of the second auxiliary solder resist layer 132, is formed to be located outside the opening 131x of the first auxiliary solder resist layer 131 and inside the edge 131b, which is the outer edge of the first auxiliary solder resist layer 131.

[0086] As a result, the solder resist layer 130 has an overlapping region 130a that is a region formed by overlapping the second solder resist sub-layer 132 on the first solder resist sub-layer 131. The dimension L of the overlapping region 130a in a plan view can be any value depending on the shape and dimensions of the first solder resist sub-layer 131 and the circuit pattern of the printed wiring group 120, but is preferably in the range of 50 μm to 200 μm, for example.

[0087] The shape of the opening 132x preferably corresponds to the shape of the opening 131x. That is, when the opening 131x is circular or has any other shape, it is preferable that the opening 132x also has a similar shape.

[0088] The thickness T2 of the second sub-solder resist layer 132 can be any value depending on the design conditions of the printed wiring board 10A, but is preferably in the range of 5 μm to 30 μm, for example. Furthermore, the thickness T2 of the second sub-solder resist layer 132 and the thickness T3 of the first sub-solder resist layer 131 preferably have a relationship of T2>T3.

[0089] 2. Manufacturing method of printed wiring board A printed wiring board 10, which is an example of a printed wiring board according to a second embodiment of the present invention, will be described. Fig. 12 and Fig. 13 are schematic cross-sectional views showing the state of the printed wiring board 10 in the process shown in the flowchart of Fig. 3, and are cross-sectional views corresponding to the cross-sectional view of line XI-XI in Fig. 12. Fig. 13 is a plan view showing the state of the printed wiring board 10 in the process shown in the flowchart of Fig. 3. Note that Fig. 3 is a flowchart of the method for manufacturing a printed wiring board according to the first embodiment, but is common to the flowchart of the method for manufacturing a printed wiring board according to the second embodiment.

[0090] (Printed circuit board manufacturing) First, a printed circuit board 100 having a printed wiring group 120 arranged on the surface of a base material 110 is prepared.

[0091] (Formation of solder resist layer) Next, the solder resist layer 130 is formed on the printed circuit board 100 .

[0092] First, in a first step, a first sub-solder resist layer 131 is formed on the surface of the lands 124 of the printed wiring group 120 by inkjet printing (step S006).

[0093] As shown in FIG. 13(B), the first sub-solder resist layer 131 has a rectangular outer shape when viewed from above, and has an opening 131x that is rectangular when viewed from above formed in the center, with a portion of the surface of the land 124 exposed so that the opening 131x is located therein.

[0094] The thickness T3 of the first sub-solder resist layer 131 can be any value depending on the design conditions of the printed wiring board 10A, but is preferably in the range of 5 μm to 20 μm, for example. In addition, it is preferable to perform the inkjet printing in an environment with a temperature of 20° C. to 25° C. and a humidity of 30% to 70%.

[0095] By using inkjet printing to print the solder resist ink 301, the openings 131x of the first solder resist sub-layer 131 can be formed in predetermined areas on the surfaces of the lands 124 with high precision.

[0096] The solder resist ink 301 used for the first sub-solder resist layer 131 is the same as that used for the printed wiring board 10 according to the first embodiment.

[0097] Next, in a second step, the second auxiliary solder resist layer 132 is formed on the printed circuit board 100 by screen printing (step S007).

[0098] The second auxiliary solder resist layer 132 is formed so as to surround from the outside the periphery of the exposed portion of the land 124, including a part of the surface of the first auxiliary solder resist layer 131 formed on the surface of the land 124, and to cover all the remaining portions of the printed circuit board 100. Specifically, as shown in FIG. 12(B), a screen plate 300 is placed on the first auxiliary solder resist layer 131, and as shown in FIG. 12(C), a solder resist ink 302 is printed so as to fill the screen openings 300x on the screen plate 300 while pressing a squeegee (not shown) against the screen plate 300 in parallel with the printed circuit board 100. Thereafter, as shown in FIG. 12(D), the screen plate 300 is removed from the printed circuit board 100, and the solder resist ink 302 is cured to form the second auxiliary solder resist layer 132.

[0099] In the above description, the second step is described as forming one second sub-solder resist layer 132 around the exposed portion of the printed circuit board 100, including the land 124, for the printed wiring board 10A having one land 124 as a land. However, the second step may be any step that forms each of the multiple first sub-solder resist layers and a second sub-solder resist layer spanning the surface of the printed circuit board in accordance with the design of the printed wiring board.

[0100] The thickness of the second sub-solder resist layer 132 can be any value depending on the design conditions of the printed wiring board 10A, but is preferably in the range of 5 μm to 20 μm, for example. Furthermore, the thickness of the second sub-solder resist layer 132 is preferably greater than the thickness of the first sub-solder resist layer 131 formed earlier. This allows the first sub-solder resist layer 131 and the second sub-solder resist layer 132 to be formed by taking advantage of the advantages of their respective printing methods. Moreover, the screen printing is preferably performed in an environment with a temperature of 20° C. to 25° C. and a humidity of 30% to 70%.

[0101] When printing the solder resist ink 302 by screen printing, the alignment of the screen plate 300 can be performed as follows: That is, a work guide is installed on the printing machine to which the screen plate 300 is attached, and the printed circuit board 100 is brought into contact with the work guide during printing, whereby alignment is performed based on the assembly accuracy of the screen plate 300 and the work guide.

[0102] The solder resist ink 302 used for the second sub-solder resist layer 132 is the same as that used for the printed wiring board 10 according to the first embodiment.

[0103] 13C shows a state in which the second sub-solder resist layer 132 is formed on the printed circuit board 100 in step S007. As shown in FIG 10, an edge 132a of an opening 132x which becomes an inner edge in the second sub-solder resist layer 132 is formed to be located outside the opening 131x of the first sub-solder resist layer 131 and inside an edge 131b which becomes an outer edge in the first sub-solder resist layer 131.

[0104] As a result, the completed solder resist layer 130 has an overlapping region 130a formed by the second solder resist sub-layer 132 overlapping the first solder resist sub-layer 131 from above.

[0105] Finally, external shape and hole processing and surface finishing are performed to complete the printed wiring board 10 (step S008). In order to clean the lands 124 and their surrounding surfaces on which the solder resist layer 130 is not formed, degreasing and rust removal are performed using, for example, acid.

[0106] The method for manufacturing printed wiring board 10A according to the second embodiment of the present invention has the same effects as the method for manufacturing printed wiring board 10 according to the first embodiment.

[0107] 3. Modification of the Second Embodiment In the method for manufacturing printed wiring board 10A according to the second embodiment, overlapping region 130a of solder resist layer 130 may be formed such that first sub-solder resist layer 131 overlaps second sub-solder resist layer 132. In this case, the order of the step of forming first sub-solder resist layer 131 by inkjet printing (step S006) and the step of forming second sub-solder resist layer 132 by screen printing (step S007) is reversed in the flowchart for explaining the method for manufacturing a printed wiring board shown in FIG.

[0108] Specifically, the completed printed circuit board 100 shown in Fig. 15(A) is prepared. Next, as shown in Fig. 15(B), a second sub-solder resist layer 132 is formed by screen printing so as to expose a part of the lands 124 of the prepared printed circuit board 100 and cover the entire remaining portion, leaving an opening 132x. The opening 132x is an opening that exposes the surface of the printed circuit board 100 including the lands 124, which will be inside the opening 131x of the first sub-solder resist layer 131 to be formed later.

[0109] 14(A) to 14(C), the specific steps of screen printing are performed by printing and curing solder resist ink 302 using a screen plate 300. Note that the details of the steps shown in each figure, the material of the solder resist ink 302, the curing conditions, etc. are the same as those in the embodiment described above with reference to FIG. 5, and therefore detailed description thereof will be omitted.

[0110] Next, as shown in Fig. 15(C), the first sub-solder resist layer 131 is formed on the printed circuit board 100 on which the second sub-solder resist layer 132 has been formed by inkjet printing of a solder resist ink 302. The first sub-solder resist layer 131 has a rectangular outer shape in a plan view and a rectangular opening 131x in a plan view at the center, and the opening 131x is arranged so as to expose a part of the second sub-solder resist layer 132 and a part of the surface of the land 124. Note that the specific details of the inkjet printing process, the material of the solder resist ink 302, the curing conditions, etc. are the same as those in the above embodiment described with reference to Fig. 5, and detailed description thereof will be omitted.

[0111] By forming the overlapping region 130a of the solder resist layer 130 so that the first sub-solder resist layer 131 overlaps the second sub-solder resist layer 132, and performing the inkjet printing after the screen printing, it is possible to precisely compensate for the variation in accuracy due to the screen printing and precisely determine the exposed range of the land 124.

[0112] As described above, the embodiment of the present invention has been disclosed in the above description, but the present invention is not limited thereto.

[0113] In other words, various modifications can be made to the above-described embodiments and each modified example in terms of mechanism, shape, material, quantity, position, arrangement, etc. without departing from the technical idea and scope of the purpose of this invention, and such modifications are included in this invention. [Explanation of symbols]

[0114] 10, 10A Printed wiring board 100 Printed Circuit Boards 110 Base material 111a Core material 111b Laminated material 112 Copper foil layer 120 Printed Wiring Group 121 First Printed Wiring 122 Second Printed Wiring 123 The third printed wiring 124 Rand 124a, 131a, 131b, 132a edges 130 Solder resist layer 130a Overlapping area 131x, 132x aperture 131 First sub-solder resist layer 132 Second solder resist layer 140 Etching resist layer 200 Laminate 300 screen version 300a Masking section 300x screen aperture 301, 302 Solder resist ink

Claims

1. forming a solder resist layer that selectively covers a surface of a printed circuit board having printed wiring including lands on a surface thereof so that at least the entire or partial surfaces of the lands are exposed; The step of forming the solder resist layer includes: A first step of forming a first sub-solder resist layer by inkjet printing; a second step of forming a second sub-solder resist layer by screen printing; having A method for manufacturing a printed wiring board, wherein, in a planar view of the printed circuit board, the first sub-solder resist layer is formed around the land, and the second sub-solder resist layer is formed around at least an edge portion of the first sub-solder resist layer that is adjacent to the periphery of the land.

2. forming an area around the land where the second solder resist layer overlaps the first solder resist layer; The method for producing the printed wiring board according to claim 1 .

3. forming an area around the land where the first solder resist layer overlaps the second solder resist layer; The method for producing the printed wiring board according to claim 1 .

4. the first step is a step of selectively forming each of the plurality of first sub-solder resist layers corresponding to all or a part of each of the plurality of lands, the second step is a step of forming the second sub-solder resist layer across each of the plurality of first sub-solder resist layers and the surface of the printed circuit board; The method for producing the printed wiring board according to claim 1 .

5. The thickness of the first sub-solder resist layer is smaller than the thickness of the second sub-solder resist layer. The method for producing the printed wiring board according to claim 1 .

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