Printed circuit board and its manufacturing method

Abstract

The present invention enables the achievement of a printed board which is able to be reliably inspected without causing an increase in the production cost. A printed board (100) according to the present invention is provided with: a substrate main body part (7) that has a surface; a pad electrode (1); a solder layer (4); and a flux coating film (5). The pad electrode (1) is formed on the surface of the substrate main body part (7). The solder layer (4) is formed on the pad electrode (1). The flux coating film (5) is arranged so as to overlap with an outer peripheral part (4b) of the solder layer (4). A surface region (4a) of the solder layer (4), the surface region (4a) being exposed from the flux coating film (5), has a first width L1 in a first direction and a second width L2 in a second direction. The second direction intersects with the first direction. The first width L1 and the second width L2 are different from each other.

Description

[Technical field]

[0001] The present disclosure relates to a printed circuit board and a method for manufacturing the same. [Background technology]

[0002] Conventionally, there is known a printed circuit board formed with an inspection electrode portion for contacting an inspection probe pin (see, for example, Japanese Patent Application Laid-Open No. 5-109443). In the above-mentioned conventional printed circuit board, it is said that poor contact of the probe pin due to flux caused by the solder paste can be avoided by arranging a conductive chip component thicker than the solder paste used for soldering as the inspection electrode portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-109443 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional printed circuit board, since conductive chip components are mounted on the printed circuit board as electrodes for inspection, the number of components mounted on the printed circuit board increases, resulting in a problem that the productivity in the manufacturing process of the printed circuit board decreases and the manufacturing cost increases.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a printed circuit board that can be reliably inspected without increasing manufacturing costs. [Means for solving the problem]

[0006] The printed circuit board according to the present disclosure comprises a board body having a surface, a pad electrode, a solder layer, and a flux coating. The pad electrode is formed on the surface of the board body. The solder layer is formed on the pad electrode. The flux coating is arranged so as to overlap an outer periphery of the solder layer. A surface area of ​​the solder layer exposed from the flux coating has a first width in a first direction and a second width in a second direction. The second direction is a direction intersecting the first direction. The first width and the second width are different.

[0007] In the method for manufacturing a printed circuit board according to the present disclosure, first, a board main body portion having a pad electrode formed on its surface is prepared. Solder paste is placed on the pad electrode. The solder paste is heated to melt and then solidified to form a solder layer on the pad electrode. The pad electrode includes a main body portion and a protruding portion. The protruding portion is connected to the outer periphery of the main body portion. In the step of forming the solder layer, a flux coating is formed so as to overlap the outer periphery of the solder layer, and a surface region that is part of the solder layer is exposed from the flux coating.

[0008] In the method for manufacturing a printed circuit board according to the present disclosure, a board main body having a pad electrode formed on its surface is prepared. Solder paste is placed on the pad electrode. The solder paste is heated to melt and then solidified to form a solder layer on the pad electrode. The pad electrode has a rectangular planar shape. In the step of forming the solder layer, a flux film is formed so as to overlap the outer periphery of the solder layer, and a surface region that is a part of the solder layer is exposed from the flux film. Effect of the Invention

[0009] According to the above, a printed circuit board that can be reliably inspected can be obtained without increasing manufacturing costs. [Brief description of the drawings]

[0010] [Figure 1] 2 is a partial schematic plan view showing an inspection electrode portion of the printed circuit board according to the first embodiment; FIG. [Diagram 2]FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. [Figure 4] 4 is a flowchart for explaining a method for manufacturing the printed circuit board shown in FIGS. 1 to 3. [Diagram 5] 4 is a partial schematic plan view for explaining a method for manufacturing the printed circuit board shown in FIGS. 1 to 3. FIG. [Figure 6] 4 is a flowchart for explaining a method for inspecting the printed circuit board shown in FIG. [Figure 7] 11 is a partial schematic plan view showing an inspection electrode portion of a printed circuit board according to a second embodiment. FIG. [Figure 8] 8 is a schematic cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 8 is a schematic cross-sectional view taken along line IX-IX in FIG. [Figure 10] 10 is a partial schematic plan view for explaining a method for manufacturing the printed circuit board shown in FIGS. 7 to 9. FIG. [Figure 11] 13 is a partial schematic plan view showing an inspection electrode portion of a printed circuit board according to a third embodiment. FIG. [Figure 12] 12 is a partial schematic plan view for explaining a method of manufacturing the printed circuit board shown in FIG. 11. [Figure 13] 13 is a partial schematic plan view showing an inspection electrode portion of a printed circuit board according to a fourth embodiment. FIG. [Figure 14] 14 is a partial schematic plan view for explaining a method of manufacturing the printed circuit board shown in FIG. 13. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described. Note that the same reference numerals are used to refer to the same components, and the description thereof will not be repeated.

[0012] Embodiment 1 <Printed circuit board configuration> Fig. 1 is a partial schematic plan view showing an inspection electrode portion of a printed circuit board according to embodiment 1. Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a schematic cross-sectional view taken along line III-III in Fig. 1. Figs. 1 to 3 show the inspection electrode portion with which a probe pin comes into contact during inspection of a printed circuit board 100.

[0013] 1 to 3, the printed circuit board 100 mainly comprises a board body 7 having a surface, a pad electrode 1, an insulating layer 3, a solder layer 4, and a flux coating 5. The pad electrode 1 is formed on the surface of the board body 7. The pad electrode 1 is an inspection electrode used to electrically connect a probe pin to perform circuit connection and functional inspection of the circuit. The pad electrode 1 is electrically connected to a wiring (not shown) drawn out from a circuit formed on the printed circuit board 100.

[0014] As shown in FIG. 5 and other figures, the pad electrode 1 includes a main body 1a and a plurality of protruding portions 1ba as protruding portions 1b. The plurality of protruding portions 1ba are connected to the outer periphery of the main body 1a. The plurality of protruding portions 1ba are arranged at intervals along the outer periphery of the main body 1a. The plurality of protruding portions 1ba are arranged at equal intervals along the outer periphery of the main body 1a. The material constituting the pad electrode 1 may be a metal having excellent wettability with the solder layer 4. For example, the material of the pad electrode 1 may be copper, nickel, gold, or the like.

[0015] The insulating layer 3 is disposed on the surface of the board main body 7. The insulating layer 3 is, for example, a solder resist, and is used to form a pattern of a soldered portion in surface mounting of the printed circuit board 100, or to protect a wiring pattern forming a circuit. The insulating layer 3 is disposed so as to surround the pad electrode 1 while being spaced apart from it. From a different perspective, an opening 3a is formed in the insulating layer 3. The pad electrode 1 is disposed inside the opening 3a. The pad electrode 1 is disposed at a distance from the inner peripheral surface of the opening 3a.

[0016] The solder layer 4 is formed on the pad electrode 1. The solder layer 4 has a planar shape that conforms to the planar shape of the pad electrode 1. Specifically, the outer peripheral edge of the solder layer 4 is arranged so as to overlap the outer peripheral edge 1d of the pad electrode 1. The solder layer 4 includes a surface region 4a and an outer peripheral portion 4b. The surface region 4a is located on the main body portion 1a of the pad electrode 1 and is a portion exposed from the flux coating 5. The outer peripheral portion 4b is arranged so as to surround the surface region 4a and is a portion located under the flux coating 5. The outer peripheral portion 4b includes a portion located on the protruding portion 1b of the pad electrode 1 and a portion located on the region 1c located between the two protruding portions 1b of the pad electrode 1.

[0017] The flux coating 5 is disposed so as to overlap the outer periphery 4b of the solder layer 4. The flux coating 5 is disposed so as to extend from the outer periphery 4b of the solder layer 4 through the surface of the board body 7 to the insulating layer 3. As shown in Figs. 1 to 3, the width (radial width) of the flux coating 5 in the direction overlapping the protruding portion 1b as viewed from the central portion 1aa of the pad electrode 1 is narrower than the width (radial width) of the flux coating in the direction overlapping the region 1c of the pad electrode 1 as viewed from the central portion 1aa. The flux coating 5 is disposed so that parts with a wide radial width and parts with a narrow radial width are alternately arranged in the circumferential direction along the outer periphery of the flux coating 5.

[0018] The surface region 4a of the solder layer 4 exposed from the flux coating 5 has a first width L1 in the first direction and a second width L2 in the second direction. The first direction is a direction along a straight line connecting the central portion 1aa of the pad electrode 1 and the two protruding portions 1ba arranged to sandwich the central portion 1aa, as shown in Figs. 1 and 2. The second direction is a direction along a straight line connecting the central portion 1aa of the pad electrode 1 and the two regions 1c arranged to sandwich the central portion 1aa, as shown in Figs. 1 and 3. As shown in Fig. 1, the second direction is a direction intersecting the first direction. The first width L1 and the second width L2 are different. The first width L1 is longer than the second width L2.

[0019] 2 and 3, the surface shape of the solder layer 4 in a cross section taken along the first direction is different from the surface shape of the solder layer 4 in a cross section taken along the second direction. Specifically, the surface shape of the outer periphery 4b of the solder layer 4 located on the protrusion 1b is different from the surface shape of the outer periphery 4b of the solder layer 4 located on the region 1c that is not the protrusion 1b. The angle that the surface of the outer periphery 4b of the solder layer 4 located on the region 1c makes with the surface of the board main body 7 is larger than the angle of the surface of the outer periphery 4b of the solder layer 4 located on the protrusion 1b.

[0020] <Printed circuit board manufacturing method> FIG. 4 is a flow chart for explaining a method for manufacturing the printed circuit board shown in FIG. 1 to FIG. 3. FIG. 5 is a partial schematic plan view for explaining a method for manufacturing the printed circuit board shown in FIG. 1 to FIG. 3. As shown in FIG. 4 and FIG. 5, in the method for manufacturing the printed circuit board 100 shown in FIG. 1 to FIG. 3, a step (S10) of preparing a board is first performed. In this step (S10), a board body part 7 having a pad electrode 1 formed on its surface is prepared. Note that an insulating layer 3 is formed on the surface of the board body part 7 so as to surround the periphery of the pad electrode 1. In the pad electrode 1, a plurality of protruding parts 1ba are formed on the outer periphery of the body part 1a. The number of the protruding parts 1ba is, for example, 8 as shown in FIG. 5. The number of the protruding parts 1ba can be set arbitrarily.

[0021] Next, a step (S20) of arranging a mask is performed. In this step (S20), a metal mask 2 is arranged on the surface of the substrate main body 7. An opening 2a is formed in the metal mask 2 as shown in FIG. 5. The metal mask 2 is arranged so that the pad electrode 1 is exposed in the opening 2a. The size of the opening 2a in the metal mask 2 is smaller than the size of the opening 3a in the insulating layer 3. In FIG. 5, the diameter of the opening 2a in the metal mask 2 is the same as the maximum outer diameter of the pad electrode 1. The area of ​​the opening 2a in the metal mask 2 may be larger than the area of ​​the pad electrode 1. The diameter (maximum width) of the opening 2a in the metal mask 2 may be smaller than the maximum outer diameter (maximum width) of the pad electrode 1. The diameter (maximum width) of the opening 2a in the metal mask 2 may be equal to or larger than the diameter (maximum width) of the main body 1a of the pad electrode 1. If the diameter of the opening 2a is smaller than the diameter of the main body 1a of the pad electrode 1, it is difficult to make the height of the solder layer 4 sufficiently high. Moreover, if the diameter of the opening 2a is set too large, it may cause defective soldering because a solder ball or the like may be formed outside the pad electrode 1. The thickness of the metal mask 2 may be, for example, 20 μm or more and 500 μm or less.

[0022] Next, a step (S30) of applying solder paste is performed. In this step (S30), the solder paste is applied so as to fill the openings 2a of the metal mask 2. As the solder paste, a paste-like material containing solder particles and flux can be used. Any method can be used to apply the solder paste, but for example, a printing method using a squeegee or the like can be applied. As a result, the solder paste is disposed on the pad electrode 1. The solder paste covers the pad electrode 1 and is disposed on the area between the adjacent protruding portions 1ba of the pad electrode 1 (the area outside the area 1c of the pad electrode 1). Thereafter, the metal mask 2 is removed.

[0023] Next, a heating step (S40) is performed to form the solder layer 4. In this step (S40), the solder paste is heated to melt and then solidified. As a result, the solder layer 4 is formed on the pad electrode 1 as a solder bump. As shown in FIG. 1, a flux coating 5 is formed so as to overlap the outer periphery 4b of the solder layer 4. The flux coating 5 is composed of components of the flux contained in the solder paste. Examples of such components include resin components. Furthermore, a surface region 4a, which is a part of the solder layer 4, is exposed from the flux coating 5. In this manner, the printed circuit board 100 shown in FIGS. 1 to 3 can be obtained.

[0024] Here, the pad electrode 1 includes a main body 1a and a plurality of protruding portions 1ba as protruding portions 1b, as shown in Fig. 5. The plurality of protruding portions 1ba are connected to the outer periphery of the main body 1a. In the circumferential direction, which is the direction along the outer periphery of the main body 1a, the plurality of protruding portions 1ba are arranged at intervals from each other. The solder paste arranged on the pad electrode 1 having such a shape is heated.

[0025] At this time, the molten solder formed by melting the solder paste aggregates to have a shape that conforms to the planar shape of the pad electrode 1. Therefore, the area of ​​the area where the molten solder aggregates is smaller than the area of ​​the solder paste applied in the above step (S30), and as a result, the height of the molten solder can be increased. In addition, the planar shape of the pad electrode 1 is not circular, but is an irregular shape in which the distance from the central part 1aa to the outer periphery varies locally. Therefore, when the molten solder aggregates into a dome shape due to surface tension, a difference occurs in the height of the molten solder between a first direction that passes over the protruding part 1b of the pad electrode 1 and a second direction that does not pass over the protruding part 1b. As a result, a periodic change in shape occurs in the circumferential direction of the pad electrode 1 regarding the surface shape of the molten solder. Due to the change in shape, a region is generated in which the flow-off of the flux on the surface of the molten solder is promoted. Therefore, as shown in FIG. 1, in the outer periphery of the solder layer 4 formed by solidifying the molten solder, the shape of the flux coating 5 changes periodically in the circumferential direction. That is, there are formed an area where the flux coating 5 is relatively concentrated and an area where the surface of the solder layer 4 is exposed from the flux coating 5. The surface area 4a of the solder layer 4 exposed from the flux coating 5 serves as a contact surface to which a terminal such as a probe pin is electrically connected during testing or the like.

[0026] <Testing method> FIG. 6 is a flow chart for explaining an inspection method for the printed circuit board 100 shown in FIG. 1. Inspection of the printed circuit board 100 includes, for example, a continuity inspection for checking for the occurrence of defects such as non-joining after solder reflow heating, and an in-line inspection such as a performance inspection. As shown in FIG. 6, in the inspection method for the printed circuit board 100 shown in FIG. 1, first, a step (S110) of contacting a probe with a solder bump is performed. In this step (S110), a probe pin of an inspection device is contacted with a solder layer 4 as a solder bump formed on a pad electrode 1 of the printed circuit board 100. As described above, since the flux coating 5 is not formed on the surface region 4a of the solder layer 4, an electrical connection between the solder layer 4 and the probe pin can be reliably performed.

[0027] In addition, since the possibility of the probe pin coming into contact with the flux coating 5 is reduced, the occurrence of poor conduction between the probe pin and the solder layer 4 caused by a part of the flux coating 5 adhering to the probe pin can be suppressed. In particular, when the functional inspection of the printed circuit board 100 is performed at high temperatures, the flux coating 5 may soften and become fluid and sticky. In this case, a large amount of the flux coating 5 may adhere to the probe pin. If a large amount of the flux coating 5 adheres to the probe pin, a problem occurs in that continuous inspection cannot be performed. In the printed circuit board 100 according to this embodiment, the possibility of the probe pin coming into contact with the flux coating 5 is reduced as described above, so the occurrence of such a problem can be effectively suppressed.

[0028] In this case, the generation of flux debris caused by the probe pin coming into contact with the flux coating 5 can also be suppressed, so that contamination of the inside of the inspection facility due to the flux debris can also be suppressed.

[0029] Next, a measuring step (S120) is performed. In this step (S120), a continuity test of the printed circuit board 100 is performed by inputting and outputting an electrical signal for testing from the probe pin to the pad electrode 1 via the solder layer 4. As described above, the electrical connection between the solder layer 4 and the probe pin of the testing device is reliably established, so that the test in the above step (S120) can be performed reliably.

[0030] <Action and effect> The printed circuit board 100 according to the present disclosure includes a board body 7 having a surface, a pad electrode 1, a solder layer 4, and a flux coating 5. The pad electrode 1 is formed on the surface of the board body 7. The solder layer 4 is formed on the pad electrode 1. The flux coating 5 is arranged so as to overlap an outer periphery 4b of the solder layer 4. The surface region 4a of the solder layer 4 exposed from the flux coating 5 has a first width L1 in a first direction and a second width L2 in a second direction. The second direction is a direction intersecting the first direction. The first width L1 and the second width L2 are different.

[0031] In this way, the shape of the flux coating 5 becomes non-uniform at the outer periphery 4b of the solder layer 4, and as a result, it is possible to reliably form the surface region 4a exposed from the flux coating 5 at the center of the solder layer 4. As a result, when the probe pin of an inspection device or the like is brought into contact with the solder layer 4, it is possible to suppress the occurrence of problems such as poor contact between the probe pin and the solder layer 4 without carrying out a process such as mounting a separate component as an inspection electrode portion on the printed circuit board 100 or cleaning the printed circuit board 100 in advance as in the conventional case. Therefore, it is possible to perform reliable inspection without increasing the manufacturing cost.

[0032] In the above-mentioned printed circuit board 100, the pad electrode 1 may include a main body portion 1a and a protruding portion 1b. The protruding portion 1b may be continuous with the outer periphery of the main body portion 1a. The first direction may be a direction from the protruding portion 1b toward the central portion 1aa of the main body portion 1a. The second direction may be a direction from a region 1c on the outer periphery of the main body portion 1a where the protruding portion 1b is not formed toward the central portion 1aa of the main body portion 1a.

[0033] In this case, since the protrusion 1b is formed on the pad electrode 1, the surface shape in the first direction can be made different from the surface shape in the second direction for the solder layer 4 formed on the pad electrode 1. As a result, the arrangement of the flux coating 5 on the surface of the solder layer 4 can be controlled, and as a result, the surface region 4a where the solder layer 4 is exposed from the flux coating 5 can be reliably formed.

[0034] In the above-mentioned printed circuit board 100, the protruding portion 1b may include a plurality of protruding portions 1ba arranged at intervals along the outer periphery of the main body portion 1a. In this case, the protruding portions 1ba and the regions 1c where the protruding portions 1ba are not formed can be formed alternately on the outer periphery of the pad electrode 1. Therefore, in the solder layer 4 formed on the pad electrode 1 by reflow heating, the portions on the protruding portions 1ba and the portions on the regions 1c can have different surface shapes. As a result, the regions of the pad electrode 1 exposed from the flux coating 5 can be reliably formed.

[0035] The length of the protruding portion 1b in the radial direction from the main body 1a of the pad electrode 1 may be, for example, 0.05 mm or more and 0.8 mm or less. If the length of the protruding portion 1b is less than 0.05 mm, the effect of agglomerating the solder paste applied outside the pad electrode 1 onto the pad electrode 1 is reduced, and there is a risk of solder balls being generated outside the pad electrode 1. If the length of the protruding portion 1b exceeds 0.8 mm, the effect of increasing the height of the agglomerated solder layer 4 is reduced.

[0036] In the above-described printed circuit board 100, the multiple protruding portions 1ba may be disposed at equal intervals along the outer periphery of the main body portion 1a. In this case, when the solder layer 4 is formed, the flux coating 5 gathers in the regions located between the multiple protruding portions 1ba. As a result, the solder layer 4 is reliably exposed from the flux coating 5 in the regions located on the multiple protruding portions 1ba.

[0037] The printed circuit board 100 may further include an insulating layer 3. The insulating layer 3 may be disposed on the surface of the board body 7. The insulating layer 3 may be disposed to be spaced apart from the pad electrode 1 and to surround the pad electrode 1. The flux coating 5 may extend from the outer periphery 4b of the solder layer 4 to the region between the pad electrode 1 and the insulating layer 3.

[0038] In this case, the area between the pad electrode 1 and the insulating layer 3 is used as the destination area of ​​the flux coating 5 that moves from the surface of the solder layer 4, so that the area of ​​the surface region 4a of the solder layer 4 that is exposed from the flux coating 5 can be increased.

[0039] In the method of manufacturing the printed circuit board 100 according to the present disclosure, first, a board main body 7 having a pad electrode 1 formed on its surface is prepared. Solder paste is placed on the pad electrode 1. The solder paste is heated to melt and then solidified to form a solder layer 4 on the pad electrode 1. The pad electrode 1 includes a main body 1a and a protruding portion 1b. The protruding portion 1b is connected to the outer periphery of the main body 1a. In the process of forming the solder layer 4, a flux coating 5 is formed so as to overlap the outer periphery 4b of the solder layer 4, and a surface region 4a that is a part of the solder layer 4 is exposed from the flux coating 5. In this manner, the printed circuit board 100 shown in FIGS. 1 to 3 can be obtained.

[0040] Embodiment 2 <Printed circuit board configuration> FIG. 7 is a partial plan view schematic diagram showing an electrode portion for inspection of a printed circuit board according to the second embodiment. FIG. 8 is a cross-sectional view schematic diagram along line VIII-VIII in FIG. 7. FIG. 9 is a cross-sectional view schematic diagram along line IX-IX in FIG. 7. The printed circuit board 100 shown in FIG. 7 to FIG. 9 basically has the same configuration as the printed circuit board 100 shown in FIG. 1 to FIG. 3, but the structures of the pad electrode 1 and the insulating layer 3 are different from those of the printed circuit board 100 shown in FIG. 1 to FIG. 3. Specifically, in the printed circuit board 100 shown in FIG. 7 to FIG. 9, a conductive layer 11 is formed on the surface of the board body 7. An insulating layer 3 is formed on the conductive layer 11. An opening 3a is formed in the insulating layer 3. A part of the conductive layer 11 is exposed from the opening 3a. The part of the conductive layer 11 exposed from the opening 3a becomes the pad electrode 1. Therefore, the planar shape of the opening 3a defines the planar shape of the pad electrode 1. The planar shape of the opening 3a includes an uneven shape on the outer periphery as shown in FIG. 10. Due to the planar shape of the opening 3a, multiple protruding portions 1ba are formed on the outer periphery of the pad electrode 1 as shown in Fig. 10. The number of projections and recesses on the outer periphery of the opening 3a can be selected arbitrarily. As a result, the number of multiple protruding portions 1ba of the pad electrode 1 can also be selected arbitrarily.

[0041] 8 and 9, the outer peripheral edge of the solder layer 4 is in contact with the inner wall of the opening 3a in the insulating layer 3. Therefore, the planar shape of the solder layer 4 is also determined by the planar shape of the opening 3a. The flux coating 5 is formed so as to extend from the outer peripheral portion of the solder layer 4 to above the insulating layer 3. The planar shapes of the flux coating 5 and the surface region 4a of the solder layer 4 are basically the same as the planar shapes of the flux coating 5 and the surface region 4a of the solder layer 4 in the printed circuit board 100 shown in FIGS. 1 to 3.

[0042] <Printed circuit board manufacturing method> The method for manufacturing the printed circuit board 100 shown in Figures 7 to 9 is basically the same as the method for manufacturing the printed circuit board 100 shown in Figures 1 to 3, but there are some differences in the step (S10) and step (S20) shown in Figure 4. This will be described in detail below.

[0043] FIG. 10 is a partial schematic plan view for explaining a method for manufacturing the printed circuit board 100 shown in FIGS. 7 to 9. In the method for manufacturing the printed circuit board 100 shown in FIGS. 7 to 9, a step (S10) of preparing a board is first performed. In this step (S10), a board main body 7 having a conductive layer 11 and an insulating layer 3 formed on its surface is prepared. The conductive layer 11 is formed on the surface of the board main body 7. The conductive layer 11 constitutes a part of the wiring layer of the circuit in the printed circuit board 100. The insulating layer 3 is formed on the conductive layer 11. As shown in FIG. 10, an opening 3a is formed in the insulating layer 3. The part of the conductive layer 11 exposed from the opening 3a corresponds to the pad electrode 1. The pad electrode 1 includes a main body 1a and a protruding portion 1b. The length of the protruding portion 1b in the pad electrode 1 in the radial direction from the main body 1a may be, for example, 0.05 mm or more and 0.8 mm or less.

[0044] Next, a step (S20) of arranging a mask is performed. In this step (S20), a metal mask 2 is arranged on the surface of the substrate main body 7. An opening 2a is formed in the metal mask 2 as shown in FIG. 10. The metal mask 2 is arranged so that the entire main body 1a and a part of the protruding portion 1b of the pad electrode 1 are exposed in the opening 2a. The diameter (maximum width) of the opening 2a of the metal mask 2 is smaller than the maximum outer diameter (maximum width) of the pad electrode 1. From a different perspective, the outer peripheral end of the protruding portion 1b of the pad electrode 1 is covered by the metal mask 2. The thickness of the metal mask 2 can be, for example, 20 μm or more and 500 μm or less. The maximum width of the opening 2a of the metal mask 2 may be the same as the maximum width of the pad electrode 1. The maximum width of the opening 2a of the metal mask 2 may be larger than the maximum width of the main body 1a of the pad electrode 1. The area of ​​the opening 2a of the metal mask 2 is preferably larger than the area of ​​the pad electrode 1.

[0045] Next, a step (S30) of applying solder paste is performed. In this step (S30), similar to the step (S30) shown in FIG. 4, the solder paste is applied so as to fill the openings 2a of the metal mask 2. As a result, the solder paste is disposed on the pad electrode 1. The solder paste covers the pad electrode 1 and is also disposed on the region between the adjacent protruding portions 1ba of the pad electrode 1 (the insulating layer 3 outside the region 1c of the pad electrode 1). Thereafter, the metal mask 2 is removed.

[0046] Next, a heating step (S40) is performed to form the solder layer 4. In this step (S40), similar to step (S40) in FIG. 4, the solder paste is heated to melt and then solidified. As a result, the solder layer 4 is formed as a solder bump on the pad electrode 1. As shown in FIG. 7, the flux coating 5 is formed so as to overlap the outer periphery 4b of the solder layer 4. The flux coating 5 extends from the outer periphery 4b of the solder layer 4 to a portion of the insulating layer 3 adjacent to the opening 3a. Also, the surface region 4a, which is a part of the solder layer 4, is exposed from the flux coating 5. In this manner, the printed circuit board 100 shown in FIGS. 7 to 9 can be obtained.

[0047] <Action and effect> In the above-mentioned printed circuit board 100, the pad electrode 1 may be a part of the conductive layer 11 formed on the surface of the board body 7. The printed circuit board 100 may further include an insulating layer 3 formed on the conductive layer 11. The insulating layer 3 may have an opening 3a formed therein to expose the part of the conductive layer 11 and define the outer shape of the pad electrode 1. In this case, in addition to the effects of the printed circuit board 100 shown in FIGS. 1 to 3, the planar shape of the pad electrode 1 can be defined by forming the opening 3a in the insulating layer 3, so that the manufacturing process of the printed circuit board 100 can be simplified compared to the case where the pad electrode 1 and the opening 3a in the insulating layer 3 are formed separately as in the printed circuit board 100 shown in FIGS. 1 to 3.

[0048] Embodiment 3 <Printed circuit board configuration> FIG. 11 is a partial schematic plan view showing an electrode portion for inspection of a printed circuit board according to the third embodiment. The printed circuit board 100 shown in FIG. 11 basically has the same configuration as the printed circuit board 100 shown in FIG. 1 to FIG. 3, but the structures of the pad electrode 1, the solder layer 4, and the insulating layer 3 are different from those of the printed circuit board 100 shown in FIG. 1 to FIG. 3. Specifically, in the printed circuit board 100 shown in FIG. 11, the pad electrode 1, the solder layer 4, and the opening 3a in the insulating layer 3 have a rectangular planar shape. The pad electrode 1 is disposed inside the opening 3a in the insulating layer 3. The pad electrode 1 is disposed at a distance from the inner peripheral surface of the opening 3a in the insulating layer 3. The opening 3a has a rectangular planar shape, which is the same as the planar shape of the pad electrode 1. The opening 3a may have a different planar shape from that of the pad electrode 1.

[0049] The solder layer 4 is formed on the pad electrode 1. The planar shape of the solder layer 4 is the same as that of the pad electrode 1. The outer peripheral edge of the solder layer 4 is arranged so as to overlap with the outer peripheral edge 1d of the pad electrode 1. The solder layer 4 includes a surface region 4a and an outer peripheral portion 4b. The surface region 4a is located on the center of the pad electrode 1 and is a portion exposed from the flux coating 5. The outer peripheral portion 4b is arranged so as to surround the surface region 4a. The outer peripheral portion 4b is located under the flux coating 5.

[0050] The flux coating 5 is disposed so as to extend from the outer periphery 4b of the solder layer 4 to the insulating layer 3. As shown in Fig. 11, the width of the flux coating 5 in the diagonal direction of the pad electrode 1 is narrower than the width of the flux coating 5 in the region overlapping with the center of the straight side of the pad electrode 1 (the width in the direction perpendicular to the straight side). The flux coating 5 is disposed so that parts with a wide radial width and parts with a narrow radial width are alternately arranged in the circumferential direction along the outer periphery of the flux coating 5.

[0051] The surface region 4a of the solder layer 4 exposed from the flux coating 5 has a first width L1 in a first direction along a diagonal line of the pad electrode 1, and a second width L2 in a second direction along one side of the outer periphery of the pad electrode 1. As shown in FIG. 11, the second direction intersects with the first direction. The first width L1 and the second width L2 are different. The first width L1 is longer than the second width L2. In the printed circuit board 100 shown in FIG. 11, the cross-sectional structure along the first direction is the same as the cross-sectional structure of the printed circuit board 100 shown in FIG. 2. In the printed circuit board 100 shown in FIG. 11, the cross-sectional structure along the second direction is the same as the cross-sectional structure of the printed circuit board 100 shown in FIG. 3.

[0052] <Printed circuit board manufacturing method> Fig. 12 is a partial schematic plan view for explaining a method for manufacturing the printed circuit board 100 shown in Fig. 11. The method for manufacturing the printed circuit board 100 shown in Fig. 11 is basically the same as the method for manufacturing the printed circuit board shown in Fig. 1 to Fig. 3. A specific description will be given below.

[0053] In the method for manufacturing the printed circuit board 100 shown in Fig. 11, a step (S10) of preparing a board is first performed. In this step (S10), a board main body 7 (see Fig. 2) having a pad electrode 1 formed on its surface is prepared. An insulating layer 3 is formed on the surface of the board main body 7. An opening 3a is formed in the insulating layer 3 so that the pad electrode 1 is exposed.

[0054] Next, a mask placement step (S20) is performed. In this step (S20), a metal mask 2 is placed on the surface of the substrate main body 7. The metal mask 2 has openings 2a formed therein as shown in FIG. 12. The metal mask 2 is placed such that the pad electrodes 1 are exposed in the openings 2a. The size of the openings 2a in the metal mask 2 is smaller than the size of the openings 3a in the insulating layer 3. In FIG. 12, the size of the openings 2a in the metal mask 2 is larger than the size of the pad electrodes 1. The planar shape of the openings 2a is rectangular. The planar shape of the openings 2a may be other shapes, such as a circle or a polygon such as a pentagon.

[0055] Next, a step (S30) of applying solder paste is performed similarly to the step (S30) shown in Fig. 4. In this step (S30), the solder paste is applied so as to fill the inside of the opening 2a of the metal mask 2. As a result, the solder paste is disposed on the pad electrode 1. The solder paste covers the top of the pad electrode 1 and is disposed on the area located outside the outer circumferential edge of the pad electrode 1. Thereafter, the metal mask 2 is removed.

[0056] Next, a heating step (S40) for forming a solder layer 4 is performed similarly to the step (S40) shown in FIG. 4. In this step (S40), the solder paste is heated to melt and then solidified. As a result, a solder layer 4 is formed on the pad electrode 1 as a solder bump. As shown in FIG. 11, a flux coating 5 is formed so as to overlap an outer periphery 4b of the solder layer 4. Also, a surface region 4a, which is a part of the solder layer 4, is exposed from the flux coating 5. In this manner, the printed circuit board 100 shown in FIGS. 1 to 3 can be obtained.

[0057] Here, the pad electrode 1 has a square planar shape as shown in FIG. 11. The solder paste arranged on the pad electrode 1 having such a shape is heated. Therefore, when the molten solder formed by melting the solder paste is condensed into a dome shape due to surface tension, a difference in height of the molten solder occurs between a first direction along the diagonal of the pad electrode 1 and a second direction along the side of the pad electrode 1. As a result, a periodic change in shape occurs in the circumferential direction of the pad electrode 1 with respect to the surface shape of the molten solder. Due to the change in shape, a region where the flow-off of the flux on the surface of the molten solder is promoted is generated. Therefore, as shown in FIG. 11, in the outer periphery of the solder layer 4 formed by solidifying the molten solder, a region where the flux coating 5 is relatively concentrated and a region where the surface of the solder layer 4 is exposed from the flux coating 5 are formed.

[0058] <Action and effect> In the above-mentioned printed circuit board 100, the planar shape of the pad electrode 1 may be a square shape. The first direction may be a direction along a diagonal line of the pad electrode 1. The second direction may be a direction along one side of the outer periphery of the pad electrode 1. In this case, the same effect as that of the printed circuit board 100 shown in FIG. 1 to FIG. 3 can be obtained. That is, the surface shape of the solder layer 4 in the cross section along the first direction is different from the surface shape of the solder layer 4 in the cross section along the second direction, and as a result, a region where the flux coating 5 is concentrated can be formed. Therefore, the surface region 4a of the solder layer 4 exposed from the flux coating 5 can be reliably formed.

[0059] The printed circuit board 100 may further include an insulating layer 3. The insulating layer 3 may be disposed on the surface of the board body 7. The insulating layer 3 may be disposed to be spaced apart from the pad electrode 1 and to surround the pad electrode 1. The flux coating 5 may extend from the outer periphery 4b of the solder layer 4 to the region between the pad electrode 1 and the insulating layer 3. In this case, the region between the pad electrode 1 and the insulating layer 3 can be used as a destination region for the flux coating 5 moving from the surface of the solder layer 4. This allows the area of ​​the surface region 4a of the solder layer 4 exposed from the flux coating 5 to be increased.

[0060] In the method of manufacturing a printed circuit board according to the present disclosure, a board main body having a pad electrode 1 formed on its surface is prepared. Solder paste is placed on the pad electrode 1. The solder paste is heated to melt and then solidified to form a solder layer 4 on the pad electrode 1. The pad electrode 1 has a rectangular planar shape. In the step of forming the solder layer 4, a flux coating 5 is formed so as to overlap an outer periphery 4b of the solder layer 4, and a surface region 4a that is a part of the solder layer 4 is exposed from the flux coating 5. In this manner, the printed circuit board 100 shown in FIG. 11 can be obtained.

[0061] Embodiment 4 <Printed circuit board configuration> FIG. 13 is a partial schematic plan view showing an electrode portion for inspection of a printed circuit board according to the fourth embodiment. The printed circuit board 100 shown in FIG. 13 basically has the same configuration as the printed circuit board 100 shown in FIG. 11, but the structures of the pad electrode 1 and the insulating layer 3 are different from those of the printed circuit board 100 shown in FIG. 11. Specifically, in the printed circuit board 100 shown in FIG. 13, a conductive layer 11 is formed on the surface of the board body. An insulating layer 3 is formed on the conductive layer 11. An opening 3a is formed in the insulating layer 3. A part of the conductive layer 11 is exposed from the opening 3a. The part of the conductive layer 11 exposed from the opening 3a becomes the pad electrode 1. The planar shape of the opening 3a defines the planar shape of the pad electrode 1. The planar shape of the opening 3a is a square. Due to the planar shape of the opening 3a, the planar shape of the pad electrode 1 also becomes a square.

[0062] The outer peripheral edge of the solder layer 4 is in contact with the inner wall of the opening 3a in the insulating layer 3. Therefore, the planar shape of the solder layer 4 is also determined by the planar shape of the opening 3a. The flux coating 5 is formed so as to extend from the outer peripheral portion of the solder layer 4 onto the insulating layer 3. The planar shapes of the flux coating 5 and the surface region 4a of the solder layer 4 are basically the same as the planar shapes of the flux coating 5 and the surface region 4a of the solder layer 4 in the printed circuit board 100 shown in FIG.

[0063] The surface region 4a of the solder layer 4 exposed from the flux coating 5 has a first width L1 in a first direction along a diagonal of the pad electrode 1, and a second width L2 in a second direction along one side of the outer periphery of the pad electrode 1. As shown in FIG. 13, the second direction intersects with the first direction. The first width L1 is longer than the second width L2. In the printed circuit board 100 shown in FIG. 13, the cross-sectional structure along the first direction is the same as the cross-sectional structure of the printed circuit board 100 shown in FIG. 8. In the printed circuit board 100 shown in FIG. 13, the cross-sectional structure along the second direction is the same as the cross-sectional structure of the printed circuit board 100 shown in FIG. 9.

[0064] <Printed circuit board manufacturing method> The method for manufacturing the printed circuit board 100 shown in Fig. 13 is basically the same as the method for manufacturing the printed circuit board 100 shown in Fig. 11, but there are some differences in the step (S10) and the step (S20) shown in Fig. 4. The details will be described below.

[0065] Fig. 14 is a partial schematic plan view for explaining a method for manufacturing the printed circuit board 100 shown in Fig. 13. In the method for manufacturing the printed circuit board 100 shown in Fig. 13, a step (S10) of preparing a board is first performed. In this step (S10), a board main body 7 (see Fig. 8) having a conductor layer 11 and an insulating layer 3 formed on its surface is prepared. The conductor layer 11 is formed on the surface of the board main body 7. The insulating layer 3 is formed on the conductor layer 11. As shown in Fig. 14, a rectangular opening 3a is formed in the insulating layer 3. The portion of the conductor layer 11 exposed from the opening 3a corresponds to the pad electrode 1.

[0066] Next, a mask placement step (S20) is performed. In this step (S20), a metal mask 2 is placed on the surface of the substrate main body 7. An opening 2a is formed in the metal mask 2 as shown in FIG. 14. The opening 2a has a rectangular shape in plan view. The metal mask 2 is placed such that the entire pad electrode 1 and a part of the insulating layer 3 are exposed in the opening 2a. The size of the opening 2a in the metal mask 2 is larger than the size of the pad electrode 1. The size of the opening 2a in the metal mask 2 may be the same as the size of the pad electrode 1.

[0067] Next, a step (S30) of applying solder paste is performed. In this step (S30), similar to the step (S30) shown in Fig. 4, the solder paste is applied so as to fill the inside of the opening 2a of the metal mask 2. As a result, the solder paste is disposed on the pad electrode 1. The solder paste covers the pad electrode 1 and is also disposed on the insulating layer 3 adjacent to the pad electrode 1. Thereafter, the metal mask 2 is removed.

[0068] Next, a heating step (S40) is carried out, which is a step of forming a solder layer 4. In this step (S40), similar to step (S40) of FIG. 4, the solder paste is heated to melt and then solidified. As a result, a solder layer 4 is formed on the pad electrode 1 as a solder bump. As shown in FIG. 13, a flux coating 5 is formed so as to overlap an outer periphery 4b of the solder layer 4. The flux coating 5 extends from the outer periphery 4b of the solder layer 4 to a portion of the insulating layer 3 adjacent to the opening 3a. Furthermore, a surface region 4a, which is a part of the solder layer 4, is exposed from the flux coating 5. In this manner, the printed circuit board 100 shown in FIG. 13 can be obtained.

[0069] <Action and effect> In the above-mentioned printed circuit board 100, the pad electrode 1 may be a part of the conductive layer 11 formed on the surface of the board body 7. The printed circuit board 100 may further include an insulating layer 3 formed on the conductive layer 11. The insulating layer 3 may be formed with an opening 3a that exposes the part of the conductive layer 11 and defines the outer shape of the pad electrode 1. In this case, in addition to the effect of the printed circuit board 100 shown in FIG. 11, the planar shape of the pad electrode 1 can be defined by forming the opening 3a in the insulating layer 3, so that the manufacturing process of the printed circuit board 100 can be simplified compared to the case where the pad electrode 1 and the opening 3a in the insulating layer 3 are formed separately as in the printed circuit board 100 shown in FIG. 11.

[0070] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Unless inconsistent, at least two of the embodiments disclosed herein may be combined. The basic scope of the present disclosure is indicated by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0071] 1 pad electrode, 1a main body, 1aa central portion, 1b protruding portion, 1ba protruding portion, 1c region, 1d outer peripheral edge, 2 metal mask, 2a, 3a openings, 3 insulating layer, 4 solder layer, 4a surface region, 4b outer peripheral portion, 5 flux coating, 7 board main body, 11 conductive layer, 100 printed circuit board.

Claims

1. A substrate body having a surface; a pad electrode formed on the surface of the substrate body; a solder layer formed on the pad electrode; a flux coating disposed so as to overlap an outer periphery of the solder layer; The surface area of ​​the solder layer exposed from the flux coating comprises: a first width in a first direction; a second width in a second direction intersecting the first direction, the first width and the second width are different; The pad electrode includes a main body and a protrusion connected to an outer periphery of the main body, the first direction is a direction from the protrusion toward a central portion of the main body, the second direction is a direction from a region on the outer periphery of the main body portion where the protrusion is not formed toward the central portion of the main body portion, an angle formed by a surface of the solder layer at an outer periphery located on the main body portion and the surface of the substrate main body portion is larger than an angle formed by a surface of the solder layer at an outer periphery located on the protruding portion and the surface of the substrate main body portion; the protrusion includes a plurality of protruding portions spaced apart along the periphery of the body portion; A printed circuit board, wherein the plurality of protruding portions and areas where the plurality of protruding portions are not formed are alternately formed on the outer periphery of the main body portion.

2. The printed circuit board according to claim 1 , wherein the plurality of protruding portions are disposed at equal intervals along the outer periphery of the main body portion.

3. an insulating layer is further provided on the surface of the substrate body portion so as to be spaced apart from the pad electrode and to surround the pad electrode; 3. The printed circuit board according to claim 1, wherein the flux coating extends from the outer periphery of the solder layer to a region between the pad electrode and the insulating layer.

4. the pad electrode is a part of a conductive layer formed on the surface of the substrate body portion, Further comprising an insulating layer formed on the conductive layer, 3. The printed circuit board according to claim 1, wherein the insulating layer has an opening that exposes the portion of the conductive layer and defines an outer shape of the pad electrode.

5. preparing a substrate body having a pad electrode formed on a surface thereof; placing a solder paste on the pad electrode; and heating the solder paste to melt it and then solidifying it to form a solder layer on the pad electrode. The pad electrode includes a main body and a protrusion connected to an outer periphery of the main body, the protrusion includes a plurality of protruding portions spaced apart along the periphery of the body portion; The plurality of protruding portions and a region where the plurality of protruding portions are not formed are alternately formed on the outer periphery of the main body portion, In the step of forming the solder layer, a flux coating is formed so as to overlap an outer periphery of the solder layer, and a surface region that is a part of the solder layer is exposed from the flux coating; A method for manufacturing a printed circuit board, wherein in the step of placing the solder paste, the solder paste covers the pad electrode and is placed on an area outside the pad electrode and adjacent to the protrusion.

Images