Manufacturing method of wiring circuit board

Abstract

To provide a manufacturing method of a wiring circuit board, having a conductive member with excellent connection reliability.SOLUTION: A present invention provides a manufacturing method of a wiring circuit board 1. The wiring circuit board 1 comprises: a base insulation layer 3; a terminal 41; and a conductive member 6. The terminal 41 is arranged to one side of the base insulation layer 3. The conductive member 6 is arranged on one surface of the terminal 41. The manufacturing method comprises a step (1) to a step (6). In the step (1), the terminal 41 is arranged on the one side of the base insulation layer 3. In the step (2), a first negative resist 7A is arranged on at least the one side of the base insulation layer 3 and the terminal 41. In the step (3), at least one part of the terminal 41 in the first negative resist 7A is masked from the other side in a thickness direction, and is exposed. In the step (4), an unexposed part 72 of the first negative resist 7A is removed by development to form a resist 75 having a first opening 74. In the step (5), the conductive member 6 is formed in the first opening 74 of the resist 75. In the step (6), the resist 75 is removed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for producing a wired circuit board. [Background technology]

[0002] Conventionally, it is known that a wired circuit board includes an insulating layer, a terminal, and a conductive member in this order in the thickness direction. The conductive member includes a plating layer. As a method for manufacturing this wired circuit board, a manufacturing method including steps (1) to (5) has been proposed (for example, see Patent Document 1 below).

[0003] In step (1), a terminal is placed on one side of the insulating layer in the thickness direction. In step (2), a negative resist is placed on at least one side of the insulating layer and the terminal. In step (3), the negative resist is exposed from one side in the thickness direction through a photomask having a light-transmitting portion and a light-shielding portion, and the unexposed portion of the negative resist corresponding to the light-shielding portion is removed by development to form a resist with an opening. In this step (3), the light-shielding portion is opposed to the terminal.

[0004] In step (4), a conductive member is formed in the opening by plating, and in step (5), the resist is removed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-232729 Summary of the Invention [Problem to be solved by the invention]

[0006] In step (3), it may be difficult to completely match the position of the light-shielding portion with the position of the terminal. For example, one edge of the light-shielding portion may be located outside one edge of the terminal in the width direction. In other words, one edge of the light-shielding portion may be misaligned with one edge of the terminal. In this case, an unintended exposed portion is formed on one side of the terminal in the width direction in the negative resist. Then, since the opening in the resist includes one side of the terminal in the width direction, in step (4), a conductive member (plating layer) is also formed on one side of the terminal in the width direction. Then, there is a problem that the above-mentioned conductive member comes into contact with the adjacent terminal, causing a short circuit between the terminals.

[0007] The present invention provides a method for producing a wired circuit board provided with a conductive member having excellent connection reliability. [Means for solving the problem]

[0008] The present invention [1] is a method for manufacturing a wired circuit board, the wired circuit board comprising an insulating layer, a terminal arranged on one side of the insulating layer in a thickness direction, and a conductive member arranged on one side of the terminal in the thickness direction, and the manufacturing method includes the steps of: placing the terminal on one side of the insulating layer in the thickness direction; placing a negative resist on one side of the insulating layer and the terminal; exposing the negative resist from the other side in the thickness direction using at least a part of the terminal as a mask; removing an unexposed portion of the negative resist by development to form a resist having a first opening corresponding to the unexposed portion; forming the conductive member in the first opening of the resist; and removing the resist.

[0009] In step (3) of this manufacturing method, the negative resist is exposed from the other side in the thickness direction using at least a part of the terminal as a mask, so that it is possible to prevent unintended formation of an unexposed part outside at least a part of the terminal. In other words, at least a part of the terminal in the negative resist can be made an unexposed part, and the part other than the terminal can be made an exposed part.

[0010] This prevents the conductive member from being formed on the outside of the terminal, and ensures that the conductive member is formed on at least one surface of a portion of the terminal in the thickness direction.

[0011] As a result, a wired circuit board having a conductive member with excellent connection reliability can be manufactured.

[0012] The present invention [2] includes the method for producing a wired circuit board described in [1], in which, in the step (2), the negative resist is placed on one side and the other side of the insulating layer and the terminal, and in the step (5), the conductive member is formed by plating.

[0013] In step (5) of this manufacturing method, the conductive member is formed by plating, which allows for batch formation in a very small area and accurate control of the thickness, thereby enabling precise control of the volume of the conductive member (solder).

[0014] The present invention [3] includes the method for manufacturing a wired circuit board according to [1] or [2], wherein the insulating layer has a light-shielding property, the insulating layer has a second opening that overlaps with at least a portion of the terminal when viewed in the thickness direction, and in the step (3), the negative resist located within the second opening when viewed in the thickness direction is exposed.

[0015] In step (3) of this manufacturing method, even if the insulating layer has light-shielding properties, the negative resist located in the second opening when viewed in the thickness direction can be reliably exposed.

[0016] The present invention [4] includes the method for manufacturing a wired circuit board described in [3], wherein the wired circuit board further includes a metal support layer arranged on the other side of the insulating layer in the thickness direction, the metal support layer having a third opening overlapping at least a portion of the terminal and the second opening when viewed in the thickness direction, and in the step (3), the negative resist located within the third opening when viewed in the thickness direction is exposed.

[0017] In step (3) of this manufacturing method, the negative resist located within the third opening can be reliably exposed while the terminals around the third opening are supported by the metal support layer when viewed in the thickness direction.

[0018] The present invention [5] further includes a process (7) of exposing the negative resist from one side in the thickness direction through a photomask having a light-transmitting portion and a light-shielding portion, and the process (7) is performed (a) after the process (2) and before the process (3), (b) simultaneously with the process (3), or (c) after the process (3) and before the process (4). In the process (7), the photomask is disposed on one side in the thickness direction of the terminal so that, when viewed in the thickness direction, both end edges of the light-shielding portion in a first direction in which the terminal extends are located inside the second opening and the third opening, and each of both end edges of the light-shielding portion in a second direction intersecting the first direction are located outside each of both end edges of the terminal in the second direction.

[0019] In this manufacturing method, both ends of the unexposed portion of the negative resist in the first direction can be positioned inside the second opening and the third opening. Therefore, both ends of the conductive member in the first direction can be positioned inside the second opening and the third opening. As a result, the conductive member can be reliably formed on the inner portion of the terminal in the first direction.

[0020] Furthermore, even if the photomask is disposed on one side of the thickness direction of the terminal in step (7) so that both ends of the light-shielding portion in the second direction are positioned outside both ends of the terminal in the second direction, both ends of the unexposed portion of the negative resist in the second direction can be aligned with both ends of the terminal in the second direction by step (4), so that the conductive member can be reliably formed across both ends of the terminal in the second direction.

[0021] The present invention [6] further includes a step (7) of exposing the negative resist from one side in a thickness direction through a photomask having a light-transmitting portion and a light-shielding portion, the step (7) being performed (a) after the step (2) and before the step (3), (b) simultaneously with the step (3), or (c) after the step (3) and before the step (4), and in the step (7), when viewed in the thickness direction, one end edge of the light-shielding portion in a first direction in which the terminal extends is located inside the second opening and the third opening, and the other end edge of the light-shielding portion in the first direction is located outside the second opening. the photomask is disposed on one side in a thickness direction of the terminal so that the other edge of the light-shielding portion in a second direction intersecting the first direction is located on the outer side relative to the one edge of the terminal in the second direction, and the wired circuit board has a mounting area in which an electronic element is mounted, and in step (7), the photomask is disposed on one side in a thickness direction of the terminal so that the other edge of the light-shielding portion is located on the opposite side of the mounting area relative to the one edge of the light-shielding portion in the first direction.

[0022] In step (7) of this manufacturing method, one edge of the unexposed portion of the negative resist in the first direction can be positioned inside the second opening and the third opening. Therefore, one edge of the conductive member in the first direction can be positioned inside the second opening and the third opening. Therefore, one end of the conductive member in the first direction can be formed in the inner part of the terminal.

[0023] On the other hand, since the other edge of the light-shielding portion in the first direction is located outside the second opening, the other edge of the unexposed portion of the negative resist in the first direction can be located outside the second opening. Therefore, the other edge of the conductive member in the first direction can be located outside the second opening and the third opening. As a result, the other end of the conductive member in the first direction is formed at the other end of the terminal.

[0024] When the electronic element is mounted in the mounting area, the electronic element can be located near one edge of the conductive member in the first direction. At one end of the conductive member in the first direction, both ends in the second direction coincide with both edges of the conductive member in the second direction, and at the other end of the conductive member in the first direction, both ends in the second direction are located outside both edges of the conductive member in the second direction. At one end of the conductive member in the first direction, even if the conductive member melts and comes into contact with the electronic element, a short circuit between adjacent conductive members can be efficiently suppressed.

[0025] The present invention [7] includes the method for producing a wired circuit board according to [1] or [2], wherein the insulating layer has light-transmitting properties. Effect of the Invention

[0026] According to the present invention, a wired circuit board having a conductive member with excellent connection reliability can be manufactured. [Brief description of the drawings]

[0027] [Figure 1] 1 is a plan view of a printed circuit board manufactured by a manufacturing method according to an embodiment of the present invention. [Diagram 2] Fig. 2A to Fig. 2C are enlarged views of the conductive member of the printed circuit board shown in Fig. 1. Fig. 2A is a plan view. Fig. 2B is a cross-sectional view taken along line XX in Fig. 2A. Fig. 2C is a cross-sectional view taken along line YY in Fig. 2A. [Diagram 3]3A to 3C are manufacturing process diagrams of a printed circuit board. The left diagram corresponds to FIG. 2B. The right diagram corresponds to FIG. 2C. FIG. 3A shows a preparation process including step (1). FIG. 3B shows a process of forming a second opening and a third opening. FIG. 3C shows steps (2) and (3). [Figure 4] Figures 4D to 4F are manufacturing process diagrams following Figure 3C. The left diagram is a manufacturing process diagram corresponding to Figure 2B. The right diagram is a manufacturing process diagram corresponding to Figure 2C. Figure 4D is step (7). Figure 4E is step (4). Figure 4F is step (5). [Diagram 5] This is step (7) in the third modified example. [Figure 6] 6A to 6C are enlarged views of a terminal of a second modified example, Fig. 6A is a plan view, Fig. 6B is a cross-sectional view taken along line XX in Fig. 6A, and Fig. 6C is a cross-sectional view taken along line YY in Fig. 6A. [Figure 7] 7A to 7D are manufacturing process diagrams of the fourth modified example. Fig. 7A shows step (3). Fig. 7B shows step (7). Fig. 7C shows step (4). Fig. 7D shows step (5). [Figure 8] FIG. 13 is an enlarged plan view of a conductive member according to a fifth modified example. [Figure 9] 13 is a cross-sectional view of a conductive member of a sixth modified example taken along the second direction. FIG. [Figure 10] 13 is a cross-sectional view taken along the second direction of a conductive member of a seventh modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] (One embodiment) With reference to Figs. 1 to 2C, a wired circuit board 1 manufactured according to one embodiment of the present invention will be described. The wired circuit board 1 has a thickness. The wired circuit board 1 has a sheet shape. The wired circuit board 1 extends in a first direction. The first direction is perpendicular to the thickness direction. The wired circuit board 1 includes a first portion 11, a second portion 12, and an intermediate portion 13. In this embodiment, the second portion 12 is disposed on one side of the intermediate portion 13 in the first direction. The first portion 11 is disposed on the other side of the intermediate portion 13 in the first direction.

[0029] The first portion 11 is disposed at the other end of the wired circuit board 1 in the first direction. The first portion 11 has a generally rectangular shape in a plan view. The first portion 11 has a mounting area 111, a wiring arrangement area 112, a terminal arrangement area 113, and a through hole 114. In other words, the wired circuit board 1 includes the mounting area 111.

[0030] The mounting area 111 is disposed in the center of the first portion 11 in the first direction. The mounting area 111 is disposed in the center of the first portion 11 in the second direction. The second direction is perpendicular to the thickness direction. The second direction intersects with the first direction. Preferably, the second direction is perpendicular to the first direction.

[0031] The wiring arrangement area 112 is disposed on the peripheral edge of the first portion 11. The wiring arrangement area 112 is disposed around the mounting area 111. The wiring arrangement area 112 has a generally rectangular frame shape in a plan view.

[0032] The terminal arrangement area 113 is disposed between the wiring arrangement area 112, which is disposed on the other side in the first direction, and the mounting area 111. The terminal arrangement area 113 extends in the second direction.

[0033] The through hole 114 overlaps with the terminal arrangement region 113. The through hole 114 penetrates the wired circuit board 1 in the thickness direction. The through hole 114 extends in the second direction.

[0034] The second portion 12 is disposed at one end of the wired circuit board 1 in the first direction.

[0035] The intermediate portion 13 is disposed between the first portion 11 and the second portion 12 in the first direction. The intermediate portion 13 connects the first portion 11 and the second portion 12 in the first direction.

[0036] As shown in FIG. 2C, the wired circuit board 1 includes a metal supporting layer 2, a base insulating layer 3 as an example of an insulating layer, a conductor layer 4, a cover insulating layer 5, and a conductive member 6.

[0037] The metal supporting layer 2 is disposed in the first portion 11, the second portion 12, and the intermediate portion 13. The metal supporting layer 2 in the first portion 11 has a third opening 21. The third opening 21 is formed in the first portion 11. In this embodiment, the third opening 21 has a generally rectangular shape in a plan view. The third opening 21 constitutes a part of the through hole 114. The metal supporting layer 2 has toughness.

[0038] Examples of the material of the metal supporting layer 2 include metals. Examples of the metals include stainless steel and copper alloys. The thickness of the metal supporting layer 2 is, for example, 10 μm or more and 300 μm or less.

[0039] The base insulating layer 3 is disposed on one surface of the metal supporting layer 2 in the thickness direction. In other words, the metal supporting layer 2 is disposed on the other surface of the base insulating layer 3 in the thickness direction. The base insulating layer 3 is disposed in a first portion 11, a second portion 12, and a middle portion 13. The base insulating layer 3 in the first portion 11 has a second opening 31.

[0040] The second opening 31 is formed in the first portion 11. In this embodiment, the second opening 31 has a generally rectangular shape in a plan view. The second opening 31 and the third opening 21 form a through hole 114. The third opening 21 overlaps with the second opening 31 when viewed in the thickness direction. The inner circumferential surface that defines the second opening 31 and the inner circumferential surface that defines the third opening 21 are continuous in the thickness direction.

[0041] In this embodiment, the base insulating layer 3 has a thick portion 32 and a thin portion 33. The thick portion 32 is thicker than the thin portion 33. The thick portion 32 is disposed in an area other than the thin portion 33. The thin portion 33 is disposed near one side of the second opening 31 in the first direction. The base insulating layer 3 is flexible.

[0042] An example of the material of the base insulating layer 3 is a resin. An example of the resin is polyimide. In this embodiment, the resin contains a light absorbing component. Therefore, the base insulating layer 3 has a light blocking property. The transmittance of the base insulating layer 3 at a wavelength of 300 to 400 nm is, for example, 50% or less, preferably 30% or less, and more preferably 5% or less. The transmittance of the base insulating layer 3 at a wavelength of 300 to 400 nm is, for example, 0% or more.

[0043] The thickness of the base insulating layer 3 is, for example, 1 μm or more and 20 μm or less. The thickness of the thick portion 32 is, for example, 5 μm or more and 20 μm or less. The thickness of the thin portion 33 is, for example, 1 μm or more and 15 μm or less. The ratio of the thickness of the thin portion 33 to the thickness of the thick portion 32 is, for example, 80% or less, preferably 50% or less, and for example, 5% or more, preferably 15% or more.

[0044] As shown in Fig. 2C, the conductor layer 4 is disposed on one surface of the base insulating layer 3 in the thickness direction. As shown in Fig. 1, the conductor layer 4 is disposed in a first portion 11, a second portion 12, and an intermediate portion 13. The conductor layer 4 has a terminal 41, a second terminal 42, and a wiring 43. In other words, the wired circuit board 1 includes the terminal 41.

[0045] The terminal 41 is arranged in the terminal arrangement region 113. The terminals 41 are arranged in parallel at intervals in the second direction. Each of the terminals 41 extends in the first direction. As shown in FIG. 2A, the terminal 41 has a rectangular shape that is long in the first direction in a plan view. The terminal 41 straddles the through hole 114. As shown in FIG. 2C, the terminal 41 is arranged on one side of the base insulating layer 3 (thin portion 33) in the thickness direction.

[0046] The terminal 41 includes one end 411A disposed at one end of the terminal 41 in the first direction, the other end 411B disposed at the other end of the terminal 41, and an intermediate portion 412 connecting them. Both end portions 411A, 411B (one end 411A, other end 411B) of the terminal 41 in the first direction are disposed on one surface of the base insulating layer 3 on both outer sides of the third opening 21 in the first direction. That is, both end portions 411A, 411B of the terminal 41 in the first direction contact one surface of the base insulating layer 3 in the thickness direction. Both end edges 411AE, 411BE of the terminal 41 in the first direction are located on both outer sides of the third opening 21, respectively.

[0047] The intermediate portion 412 of the terminal 41 in the first direction is located within the through hole 114 in a plan view. The intermediate portion 412 of the terminal 41 in the first direction is exposed from the through hole 114. In other words, the second opening 31 of the base insulating layer 3 overlaps with the intermediate portion 412 of the terminal 41 when viewed in the thickness direction. The intermediate portion 412 is disposed on one side of the base insulating layer 3 (thin portion 33) in the thickness direction.

[0048] 1, the second terminal 42 is disposed in the second portion 12. The second terminal 42 is disposed on one surface of the base insulating layer 3 in the thickness direction. A plurality of second terminals 42 are disposed at intervals from each other.

[0049] The wiring 43 is arranged in the intermediate portion 13 and in the wiring arrangement region 112 in the first portion 11. The wiring 43 is arranged on one surface of the base insulating layer 3 in the thickness direction. The wiring 43 connects the terminal 41 and the second terminal 42. In the first portion 11, the wiring 43 is routed in the wiring arrangement region 112 so as to bypass the mounting region 111, and reaches the other end of the terminal 41 in the first direction. The wiring 43 has a portion extending from the other end edge of the terminal 41 in the first direction to the other side in the first direction.

[0050] The thickness of the conductor layer 4 is, for example, not less than 3 μm and not more than 30 μm.

[0051] The width (length in the second direction) of the terminal 41 is, for example, 30 μm or less, further 20 μm or less, further 15 μm or less, further 10 μm or less, and for example, 3 μm or more. The interval between adjacent terminals 41 in the second direction is, for example, 20 μm or less, further 15 μm or less, further 10 μm or less, and for example, 3 μm or more. If the width and / or interval of the terminals 41 is equal to or less than the above-mentioned upper limit, the terminals 41 can be arranged at high density, but the terminals 41 are likely to short-circuit through the molten conductive member 6. However, in the present embodiment, as described above, the conductive member 6 can be reliably formed only on one side of the terminal 4, so that the terminals 41 can be arranged at high density while suppressing short-circuiting of the terminals 41.

[0052] Examples of the material of the conductor layer 4 include a conductor. Examples of the conductor include copper. A protective plating layer (not shown) may be disposed on the surface of the terminal 41. Examples of the material of the protective plating layer include nickel and gold.

[0053] The cover insulating layer 5 is disposed in the first portion 11, the second portion 12, and the intermediate portion 13. As shown in FIG. 2C, the cover insulating layer 5 is disposed on one surface of the base insulating layer 3 in the thickness direction. The cover insulating layer 5 covers the wiring 43. The terminal 41 and the second terminal 42 are exposed from the cover insulating layer 5. The thickness of the cover insulating layer 5 is, for example, 1 μm or more and 25 μm or less.

[0054] As shown in FIG. 2A, the conductive member 6 is arranged in the terminal arrangement region 113. A plurality of conductive members 6 are provided corresponding to a plurality of terminals 41. As shown in FIG. 2C, the conductive member 6 is arranged on one side of the terminal 41 in the thickness direction. More specifically, as shown in FIG. 2B, the conductive member 6 is arranged on one side of the intermediate portion 412 in the thickness direction. On the other hand, the conductive member 6 is not arranged on both side surfaces of the intermediate portion 412 (terminal 41) in the second direction. As shown in FIG. 2A, the conductive member 6 has a rectangular flat plate shape in a plan view. As shown in FIG. 2B, both side surfaces 61A, 61B of the conductive member 6 in the second direction are continuous with both side surfaces 4121A, 4121B of the intermediate portion 412 in the second direction. That is, both end edges 62A, 62B of the conductive member 6 in the second direction match both end edges 4122A, 4122B of the intermediate portion 412 in the second direction when viewed in the thickness direction.

[0055] 2C, both end edges 63A, 63B of the conductive member 6 in the first direction are disposed inside the through hole 114 in the first direction. In particular, both end edges 63A, 63B of the conductive member 6 in the first direction are disposed inside the third opening 21 and the second opening 31, respectively, in the first direction.

[0056] The conductive member 6 has a width (length in the second direction) of the same size as the width (length in the second direction) of the terminal 41 (middle portion 412). The conductive member 6 has a thickness of, for example, 1 μm or more, preferably 5 μm or more, and for example, 100 μm or less, preferably 50 μm or less. If the thickness of the conductive member 6 is equal to or more than the above-mentioned lower limit, the connection reliability with the electronic element 9 described later can be improved. If the thickness of the conductive member 6 is equal to or less than the above-mentioned upper limit, short-circuiting between adjacent terminals 41 can be effectively suppressed.

[0057] The material of the conductive member 6 may be any one selected from the group consisting of Sn, SnAg alloy, SnBi alloy, SnCu alloy, and SnCo alloy, for example. The material of the conductive member 6 is preferably any one selected from the group consisting of SnAg alloy, SnBi alloy, SnCu alloy, and SnCo alloy.

[0058] Next, a method for manufacturing the wired circuit board 1 will be described. The method for manufacturing the wired circuit board 1 includes step (8), step (1), step (2), step (3), step (7), step (4), step (5), and step (6). In the manufacturing method, step (8), step (1), step (2), step (3), step (7), step (4), step (5), and step (6) are carried out in this order. Each step will be described below in order.

[0059] As shown in FIG. 3A, in step (8), first, a metal supporting layer 2 and a base insulating layer 3 are prepared. For example, the base insulating layer 3 is formed by photolithography on one surface of the sheet-shaped metal supporting layer 2 in the thickness direction. The base insulating layer 3 has a thick portion 32 and a thin portion 33. In step (8), the metal supporting layer 2 does not yet have a third opening 21 (see FIG. 3B). The base insulating layer 3 does not yet have a second opening 31 (see FIG. 3B).

[0060] As shown in Fig. 3A, in step (1), the conductor layer 4 is disposed on one surface of the base insulating layer 3 in the thickness direction. In other words, in step (1), the terminal 41 is disposed on one side of the base insulating layer 3 in the thickness direction. For example, the conductor layer 4 is formed by an additive method or a subtractive method. Then, the cover insulating layer 5 is formed on one surface of the base insulating layer 3 by photolithography.

[0061] As shown in FIG. 3B, the through hole 114 is then formed. For example, etching or laser processing is used to form the through hole 114. Specifically, the third opening 21 is formed in the metal support layer 2, and then the second opening 31 is formed in the base insulating layer 3. The thin portion 33 disposed on the other side of the intermediate portion 412 in the thickness direction is removed, and the second opening 31 is formed in the base insulating layer 3. As a result, the intermediate portion 412 is exposed on the other side in the thickness direction.

[0062] 3C, next, in step (2), negative resist 7 is placed on both one side and the other side of the base insulating layer 3 and the conductor layer 4. In other words, in step (2), the negative resist 7 is placed on at least one side of the base insulating layer 3 and the terminal 41 in the thickness direction.

[0063] The negative resist 7 is capable of forming an image (pattern) that is hardened by exposure and is not removed by development. In other words, the exposed portions 71 of the negative resist 7 are hardened and are not removed by development, and the unexposed portions 72 of the negative resist 7 are not hardened and are removed by development. The exposed portions 71 and the unexposed portions 72 constitute a latent image 73. In other words, the negative resist 7 is capable of forming the latent image 73 by exposure through a mask.

[0064] In this embodiment, the negative resist 7 is a dry film resist. The negative resist 7 has a sheet shape extending in a first direction and a second direction. Specifically, the negative resist 7 includes a first negative resist 7A and a second negative resist 7B.

[0065] The first negative resist 7A is disposed on one side in the thickness direction of the base insulating layer 3. The first negative resist 7A contacts one surface in the thickness direction of the base insulating layer 3, and one surface and a side surface of the conductor layer 4 in the thickness direction.

[0066] The second negative resist 7B is disposed on the other side of the base insulating layer 3 in the thickness direction. In this embodiment, the second negative resist 7B contacts the other surface of the metal support layer 2 in the thickness direction. A portion of the second negative resist 7B fills the through hole 114. The second negative resist 7B in the through hole 114 contacts the other surface of the intermediate portion 412 of the terminal 41.

[0067] As shown by the arrow in Fig. 3C, in step (3), the negative resist 7 is exposed from the other side in the thickness direction. Then, first, the entire second negative resist 7B is exposed. At the same time as the exposure of the second negative resist 7B, the first negative resist 7A located in the second opening 31 and the third opening 21 when viewed in the thickness direction is exposed, using the metal support layer 2 (and the light-shielding base insulating layer 3) as a mask.

[0068] In step (3), the first negative resist 7A is exposed from the other side in the thickness direction using the intermediate portion 412, which is a part of the terminal 41, as a mask. In detail, when the first negative resist 7A in the second opening 31 and the third opening 21 (through hole 114) is exposed from the other side in the thickness direction, the intermediate portion 412 blocks the light, and an unexposed portion 72 is formed in the first negative resist 7A. The unexposed portion 72 has the same pattern as the intermediate portion 412. Also, when viewed in the thickness direction, the intermediate portion 412 serves as a mask, and the first negative resist 7A other than the intermediate portion 412 (around the intermediate portion 412) is exposed in the through hole 114, and an exposed portion 71 is formed. The exposed portion 71 has a reverse (inverted) pattern of the intermediate portion 412. That is, a latent image 73 consisting of the above-mentioned exposed portion 71 and unexposed portion 72 is formed in the first negative resist 7A.

[0069] As shown in FIG. 4D, step (7) is performed after step (3). In step (7), the first negative resist 7A is exposed from one side in the thickness direction through a photomask 8. The photomask 8 has a light-transmitting portion 81 and a light-shielding portion 82. A single photomask 8 is provided with a plurality of light-shielding portions 82 corresponding to a plurality of terminals 41 (conductive members 6). An example of the photomask 8 is a glass mask.

[0070] In step (7), the photomask 8 is positioned on one side of the thickness direction of the conductor layer 4 so that, when viewed in the thickness direction, both end edges 821A, 821B of the light-shielding portion 82 in the first direction are located inside the second opening 31 and the third opening 21 (right side view of Figure 4D) and both end edges 822A, 822B of the light-shielding portion 82 in the second direction are located outside the both end edges 4122A, 4122B of the terminal 41 in the second direction (left side view of Figure 4D).

[0071] As shown in the left diagram of FIG. 4D, in step (7), both ends 822A, 822B of the light shielding portion 82 in the second direction are positioned outside both ends 4122A, 4122B of the terminal 41 in the second direction, and even if the first negative resist 7A is exposed, the unexposed portion 72 formed on one side of the intermediate portion 412 in the thickness direction maintains the unexposed portion 72 (unexposed state). On the other hand, the exposed portion 71 formed on the outside of the intermediate portion 412 overlaps both ends 822A, 822B of the light shielding portion 82 when viewed in the thickness direction, and even if it includes a part that will be unexposed in step (7), it still maintains the exposed portion 71 (exposed state) because it has already been exposed in step (3) (see FIG. 3C). In short, even in step (7), the shape of the latent image 73 of the first negative resist 7A does not change when the intermediate portion 412 is viewed in a cross section along the second direction.

[0072] As shown in the right diagram of FIG. 4D, the unexposed portion 72 facing the light-transmitting portion 81 becomes the exposed portion 71 by the exposure in step (7). That is, the unexposed portion 72 in step (3) forms a new exposed portion 71 in step (7). In short, in step (7), when the intermediate portion 412 is viewed in a cross section along the first direction, the shape of the latent image 73 of the first negative resist 7A changes. Specifically, a new latent image 73 is formed that corresponds to both end edges 63A, 63B of the conductive member 6 in the first direction.

[0073] As shown in FIG. 4E, step (4) is performed after step (7). In other words, step (7) is performed before step (4). In step (4), the unexposed portion 72 of the first negative resist 7A is removed by development. A resist 75 having a first opening 74 corresponding to the unexposed portion 72 is formed. In step (4), the second negative resist 7B is the exposed portion 71, and is therefore not removed by development, that is, it does not form a pattern and becomes a solid resist 75. This resist 75 protects the other surface of the intermediate portion 412 in the thickness direction and the other surface of the metal support layer 2 in the thickness direction.

[0074] As shown in FIG. 4F, in step (5), the conductive member 6 is formed in the first opening 74 of the resist 75. In this embodiment, in step (5), the conductive member 6 is formed by plating. Specifically, the partially manufactured wired circuit board 1B having the resist 75 is immersed in a plating solution. For example, electrolytic plating or electroless plating is used as the plating. Preferably, electrolytic plating is used as the plating. In electrolytic plating, a current is supplied to the conductive layer 4 from a plating lead (not shown) connected to the conductive layer 4. This causes the material of the conductive member 6 in the plating solution to precipitate (deposit) on one surface of the terminal 41 in the first opening 74. In step (5) of this embodiment, the conductive member 6 is formed by plating, so the resist 75 is a plating resist.

[0075] Thereafter, as shown in FIG. 2B and FIG. 2C, in step (6), the resist 75 is removed. In removing the resist 75, for example, a stripping liquid is used. For example, an alkaline liquid is used as the stripping liquid. For example, an amine stripping liquid or a sodium hydroxide stripping liquid is used as the alkaline liquid.

[0076] In this way, the wired circuit board 1 is manufactured.

[0077] 2A and 2C, the electronic element 9 is mounted on one surface of the mounting area 111 in the thickness direction. Then, the conductive member 6 is reflowed by heating to electrically connect the electrode 91 of the electronic element 9 and the terminal 41.

[0078] (Effects of one embodiment) 3C, in step (3) of this manufacturing method, the first negative resist 7A is exposed from the other side in the thickness direction using the intermediate portion 412 of the terminal 41 as a mask, so that the outside of the intermediate portion 412 of the terminal 41 can be reliably exposed. This makes it possible to prevent unintended unexposed portions 72 from being formed outside the intermediate portion 412 of the terminal 41. In other words, the intermediate portion 412 of the terminal 41 in the first negative resist 7A can be made the unexposed portion 72, and the portion other than the intermediate portion 412 can be made the exposed portion 71.

[0079] Therefore, the conductive member 6 is prevented from being formed on the outside of the terminal 41, and the conductive member 6 can be reliably formed on one surface of the intermediate portion 412 of the terminal 41 in the thickness direction.

[0080] As a result, it is possible to manufacture the wired circuit board 1 having the conductive member 6 with excellent connection reliability.

[0081] In step (5) of this manufacturing method, the conductive member 6 is formed by plating, which allows for batch formation in a very small area and accurate control of the thickness, allowing for precise control of the volume of the conductive member 6 (solder).

[0082] In this manufacturing method, the base insulating layer 3 has a light-shielding property, and the base insulating layer 3 has a second opening 31 that overlaps with the middle portion 412 of the terminal 41 when viewed in the thickness direction. Therefore, in step (3), the first negative resist 7A located in the second opening 31 when viewed in the thickness direction can be reliably exposed using the middle portion 412 of the terminal 41 as a mask.

[0083] In step (3), the metal support layer 2 supports the terminal 41 (both ends 411A, 411B) around the third opening 21 when viewed in the thickness direction. The metal support layer 2 has a light-shielding property and has the third opening 21 that overlaps with the middle portion 412 of the terminal 41 and the second opening 31 when viewed in the thickness direction, and in step (3), the first negative resist 7A located within the third opening 21 when viewed in the thickness direction can be reliably exposed using the middle portion 412 of the terminal 41 as a mask.

[0084] 4D, in step (7) of this manufacturing method, both end edges 821A, 821B of light-shielding portion 82 in the first direction are located inside second opening 31 and third opening 21. Therefore, both end edges 821A, 821B of unexposed portion 72 of first negative resist 7A in the first direction can be located inside second opening 31 and third opening 21. As a result, conductive member 6 can be reliably formed in the inner portion of terminal 41 in the first direction, i.e., intermediate portion 412.

[0085] 4D, even if the photomask 8 is disposed on one side in the thickness direction of the terminal 41 so that both ends 822A, 822B of the light-shielding portion 82 in the second direction are positioned outside both ends 4122A, 4122B of the terminal 41 in the second direction in step (7), both ends of the unexposed portion 72 of the first negative resist 7A in the second direction can be aligned with both ends 4122A, 4122B of the terminal 41 in the second direction by step (3). Therefore, the conductive member 6 can be reliably formed from the end edge 4122A to the other end edge 4122B of the terminal 41 in the second direction.

[0086] (Modification) In the modified example, the same reference numerals are used for the same components and steps as those in the first embodiment, and detailed descriptions thereof will be omitted. In addition, the modified example can achieve the same effects as those in the first embodiment, unless otherwise specified. Furthermore, the first embodiment and its modified example can be appropriately combined.

[0087] (First Modification) In step (4), the conductive members 6 may be formed by coating instead of plating. In the first modified example, a paste containing the material of the conductive members 6 is applied to (the first openings 74 of) the first negative resist 7A. Then, the paste fills the first openings 74. The paste is then dried. In the first modified example, the negative resist 7 may include only the first negative resist 7A. In step (2) of the first modified example, the negative resist 7 may be disposed only on one side of the base insulating layer 3 in the thickness direction.

[0088] (Second Modification) Although not shown, step (7) may be carried out (a) after step (2) and before step (3), or (b) simultaneously with step (3).

[0089] (Third Modification) As shown in FIG. 5, one light shielding portion 82 may be provided on the photomask 8 so as to encompass the multiple terminals 41 in the second direction.

[0090] (Fourth Modification) The wired circuit board 1 manufactured by the manufacturing method of the fourth modified example will be described with reference to FIGS. 6A to 6C.

[0091] As shown in Figure 6C, the other side 351 of the inner edge 35 of the base insulating layer 3 that defines the second opening 31 is located on one side (inner side) in the first direction with respect to the other side 251 of the inner edge 25 of the metal support layer 2 that defines the third opening 21.

[0092] As shown in FIG. 6A, the conductive member 6 has a substantially T-shape in plan view. As shown in FIG. 6C, the other end 64 of the conductive member 6 in the first direction is disposed on one surface of the base insulating layer 3 in the thickness direction. The other end edge 63B of the conductive member 6 in the first direction is located outside the second opening 31 in the first direction. As shown in FIG. 6A, the other end 64 of the conductive member 6 in the first direction has protrusions 65A and 65B. The protrusions 65A and 65B protrude to both outsides in the second direction relative to the terminal 41 when projected in the thickness direction. As shown in FIG. 6B, the protrusions 65A and 65B contact one surface of the base insulating layer 3 and the side surface of the other end 411B of the terminal 41.

[0093] 7A, the first negative resist 7A disposed on one side of the base insulating layer 3 in step (3) is an unexposed portion 72. That is, the base insulating layer 3 functions as a mask by exposure from the other side in step (3). However, even in the first negative resist 7A in the second opening 31, the first negative resist 7A around the intermediate portion 412 forms an exposed state 72.

[0094] As shown in Fig. 7B, in step (7), when viewed in the thickness direction, one end edge 821A of the light shielding portion 82 in the first direction is located inside the second opening 31 and the third opening 21 (right side view of Fig. 7B), the other end edge 821B of the light shielding portion 82 is located outside the second opening 31 (right side view of Fig. 7B), and each of both end edges 822A, 822B of the light shielding portion 82 in the second direction is located outside each of both end edges 4122A, 4122B of the terminal in the second direction (left side view of Fig. 7B), so that the photomask 8 is arranged on one side in the thickness direction of the terminal 41. Also, in step (7), the other end edge 821B of the light shielding portion 82 is located on the opposite side of the mounting region 111 (see imaginary lines in Figs. 6A and 6C) to one end edge 821A of the light shielding portion in the first direction.

[0095] (Function and effect of the fourth modified example) As shown in the right diagram of Fig. 7B, in step (7) of this manufacturing method, one edge of unexposed portion 72 of first negative resist 7A in the first direction can be positioned inside second opening 31 and third opening 21. Therefore, as shown in the right diagram of Fig. 7D, one edge 63A of conductive member 6 in the first direction can be positioned inside second opening 31 and third opening 21. Therefore, one end of conductive member 6 in the first direction can be formed in the inner portion of terminal 41, i.e., intermediate portion 412.

[0096] On the other hand, as shown in the right diagram of Fig. 7B, the other edge of the unexposed portion 72 of the first negative resist 7A in the first direction can be positioned outside the second opening 31. Therefore, as shown in the right diagram of Fig. 7D, the other edge 63B of the conductive member in the first direction can be positioned outside the second opening 31. As a result, the other end of the conductive member 6 in the first direction is formed at the other end 411B of the terminal 41.

[0097] 6A and 6C, when the electronic element 9 (virtual line) is mounted in the mounting area 111, the electronic element 9 can be located near one end edge 63A of the conductive member 6 in the first direction. Even when the conductive member 6 melts at one end edge 63A of the conductive member 6 in the first direction and flows toward the electrode 91 of the electronic element 9 and comes into contact with the electrode 91, a short circuit between adjacent conductive members 6 in the first direction can be efficiently suppressed.

[0098] (Fifth Modification) 8, the other end 64 of the conductive member 6 may include one protruding portion 65A and not include the other protruding portion 65B. The conductive member 6 has a generally L-shape in plan view.

[0099] (Sixth and seventh modified examples) The insulating base layer 3 may be light-transmitting. In step (3), the insulating base layer 3 is disposed on the other surface of the intermediate portion 412 of the terminal 41. Light from the other side in the thickness direction passes through the insulating base layer 3 having light-transmitting properties, and the intermediate portion 412 can function as a mask.

[0100] (Sixth Modification) As shown in FIG. 9, both end edges 34A, 34B in the second direction of the base insulating layer 3 arranged on the other side of the intermediate portion 412 may coincide with both end edges 4122A, 4122B of the intermediate portion 412 when viewed in the thickness direction.

[0101] (Seventh Modification) As shown in FIG. 10, both end edges 34A, 34B in the second direction of the base insulating layer 3 arranged on the other side of the intermediate portion 412 may be located inside both end edges 4122A, 4122B of the intermediate portion 412 when viewed in the thickness direction. [Explanation of symbols]

[0102] 1 Wiring circuit board 2 Metal support layer 21 Third Opening 3. Base insulation layer (an example of an insulation layer) 31 Second Opening 34A,34B Edge 4 Conductor Layer 41 Terminal 411AE, 411BE Edge (insulating layer) 412 Middle part (part of terminal) 4122A,4122B Edge 5 Cover insulation layer 6 Conductive materials 62A,62B Edge 63A,63B Edge 7B 2nd Negative Resist 72 Unexposed area 74 First Opening 75 Resist 8. Photomask 81 Translucent part 82 Light shielding part 821A, 821B Edge (light-shielding portion in the first direction) 822A, 822B Edge (shading part in the second direction) 9 Electronic elements 114 Through hole

Claims

1. A method for manufacturing a wired circuit board, the wired circuit board includes an insulating layer, a terminal disposed on one side of the insulating layer in a thickness direction, and a conductive member disposed on one surface of the terminal in the thickness direction; The manufacturing method includes: A step (1) of disposing the terminal on one side of the insulating layer in a thickness direction; (2) placing a negative resist on at least one side of the insulating layer and the terminal; (3) exposing the negative resist from the other side in the thickness direction using at least a part of the terminal as a mask; (4) removing the unexposed portions of the negative resist by developing to form a resist having a first opening corresponding to the unexposed portions; forming the conductive member in the first opening of the resist; A step (6) of removing the resist; A method for manufacturing a wired circuit board comprising the steps of:

2. In the step (2), the negative resist is disposed on one side and the other side of the insulating layer and the terminal; The method for producing a wired circuit board according to claim 1 , wherein in the step (5), the conductive member is formed by plating.

3. The insulating layer has a light-shielding property, the insulating layer has a second opening overlapping at least a portion of the terminal when viewed in a thickness direction; 3. The method for producing a wired circuit board according to claim 1, wherein in the step (3), the negative resist located in the second opening when viewed in the thickness direction is exposed to light.

4. the printed circuit board further includes a metal support layer disposed on the other surface of the insulating layer in the thickness direction, the metal support layer has a third opening overlapping at least a portion of the terminal and the second opening when viewed in a thickness direction; 4. The method for producing a wired circuit board according to claim 3, wherein in the step (3), the negative resist located in the third opening when viewed in the thickness direction is exposed to light.

5. The method further includes a step (7) of exposing the negative resist from one side in a thickness direction through a photomask having a light-transmitting portion and a light-shielding portion, The step (7) is (a) after the step (2) and before the step (3); (b) simultaneously with the step (3), or (c) carried out after step (3) and before step (4); 5. The method for manufacturing a wired circuit board according to claim 4, wherein in the step (7), the photomask is arranged on one side of the thickness direction of the terminal so that, when viewed in the thickness direction, both end edges of the light-shielding portion in a first direction in which the terminal extends are located inside the second opening and the third opening, and both end edges of the light-shielding portion in a second direction intersecting the first direction are located outside respectively both end edges of the terminal in the second direction.

6. The method further includes a step (7) of exposing the negative resist from one side in a thickness direction through a photomask having a light-transmitting portion and a light-shielding portion, The step (7) is (a) after the step (2) and before the step (3); (b) simultaneously with the step (3), or (c) carried out after step (3) and before step (4); In the step (7), the photomask is disposed on one side of the thickness direction of the terminal such that, when viewed in the thickness direction, one end edge of the light-shielding portion in a first direction in which the terminal extends is located inside the second opening and the third opening, the other end edge of the light-shielding portion in the first direction is located outside the second opening, and both end edges of the light-shielding portion in a second direction intersecting the first direction are located outside relative to both end edges of the terminal in the second direction; the printed circuit board has a mounting area on which an electronic element is mounted, 5. The method for manufacturing a wired circuit board according to claim 4, wherein in the step (7), the photomask is arranged on one side in a thickness direction of the terminal so that the other edge of the light-shielding portion is located on an opposite side of the mounting area with respect to the one edge of the light-shielding portion in the first direction.

7. The method for producing a wired circuit board according to claim 1 , wherein the insulating layer is light-transmitting.

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