Method for manufacturing printed circuit board

Abstract

The invention provides a method for manufacturing a printed circuit board (1). A wired circuit board is provided with a base insulating layer (3), a terminal (41), and a conductive member (6). The terminal is arranged on one side of the substrate insulating layer. The conductive member is disposed on a surface on one side of the terminal. The manufacturing method includes a first step to a sixth step. In the first step, the terminal is disposed on one side of the base insulating layer. In the second step, a first negative resist (7A) is disposed on at least one of the base insulating layer and the terminal. In the third step, the first negative resist is exposed from the other side in the thickness direction using at least a portion of the terminal as a mask. In the fourth step, an unexposed portion (72) of the first negative resist (7A) is removed by development to form a resist (75) having a first opening (74). In the fifth step, a conductive member is formed in the first opening of the resist. In the sixth step, the resist is removed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a wiring circuit substrate. Background Art

[0002] In the past, it is known that a wiring circuit substrate has an insulating layer, a terminal, and a conductive member in order in the thickness direction. The conductive member includes a plating layer. As a manufacturing method of the wiring circuit substrate, a manufacturing method including the first step to the fifth step is proposed (for example, refer to the following patent document 1.).

[0003] In the first step, the terminal is arranged on one side in the thickness direction of the insulating layer. In the second step, a negative resist is arranged on at least one side of the insulating layer and the terminal. In the third step, 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 an unexposed portion of the negative resist corresponding to the light-shielding portion is removed by development to form a resist having an opening. In the third step, the light-shielding portion is made to face the terminal.

[0004] In the fourth step, a conductive member is formed in the opening by plating. In the fifth step, the resist is removed.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 9-232729 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] In the third step, it is sometimes difficult to make the position of the light shielding portion completely consistent with the position of the terminal. For example, sometimes one end edge of the light shielding portion is located on the outside relative to one end edge of the terminal in the width direction. In other words, there is a case where one end edge of the light shielding portion is offset relative to one end edge of the terminal. In this case, in the negative resist, an unexpected exposure portion is formed on one side in the width direction of the terminal. Therefore, since the opening of the resist includes a portion located on one side of the terminal in the width direction, in the fourth step, a conductive member (plating) is also formed on one side of the terminal in the width direction. Therefore, there is an undesirable situation in which the above-mentioned conductive member contacts the adjacent terminal and a short circuit occurs between the terminals.

[0010] The present invention provides a method for producing a printed circuit board including a conductive member having excellent connection reliability.

[0011] Solutions for solving problems

[0012] The present invention [1] provides a method for manufacturing a wiring circuit substrate, wherein the wiring circuit substrate comprises: an insulating layer; a terminal, which is arranged on one side in the thickness direction of the insulating layer; and a conductive member, which is arranged on a surface of one side in the thickness direction of the terminal, the manufacturing method comprising: a first step, in which the terminal is arranged on one side in the thickness direction of the insulating layer; a second step, in which a negative resist is arranged on one side of the insulating layer and the terminal; a third step, in which the negative resist is exposed from the other side in the thickness direction using at least a portion of the terminal as a mask; a fourth step, in which the unexposed portion of the negative resist is removed by development to form a resist having a first opening corresponding to the unexposed portion; a fifth step, in which the conductive member is formed in the first opening of the resist; and a sixth step, in which the resist is removed.

[0013] In the third step of the manufacturing method, since the negative resist is exposed from the other side in the thickness direction using at least a portion of the terminal as a mask, it is possible to suppress the formation of an unexpected unexposed portion outside at least a portion of the terminal. In other words, the portion of the negative resist located at at least a portion of the terminal can be made an unexposed portion, and the portion other than at least a portion of the terminal can be made an exposed portion.

[0014] Therefore, it is possible to suppress the conductive member from being formed outside the terminal, and the conductive member can be reliably formed on one surface in the thickness direction of at least a portion of the terminal.

[0015] As a result, a printed circuit board including a conductive member having excellent connection reliability can be manufactured.

[0016] The present invention [2] is based on the method for manufacturing a wiring circuit board described in [1], wherein in the second step, the negative resist is arranged on one side and the other side of the insulating layer and the terminal, and in the fifth step, the conductive member is formed by plating.

[0017] In the fifth step of the manufacturing method, since the conductive member is formed by plating, the conductive member can be formed in a micro region at once and the thickness can be accurately controlled, so the volume of the conductive member (solder) can be precisely controlled.

[0018] The present invention [3] is based on the manufacturing method of the wiring circuit substrate described in [1] or [2], wherein the insulating layer has a light-shielding property, and 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 third step, the negative resist located in the second opening when viewed in the thickness direction is exposed.

[0019] In the third step of this manufacturing method, even if the insulating layer has a light-shielding property, the negative resist located in the second opening when viewed in the thickness direction can be reliably exposed.

[0020] The present invention [4] is based on the manufacturing method of the wiring circuit substrate described in [3], wherein the wiring circuit substrate also has a metal supporting layer arranged on the surface of the other side of the thickness direction of the insulating layer, and the metal supporting layer has a third opening overlapping with at least a portion of the terminal and the second opening when viewed in the thickness direction. In the third step, the negative resist located in the third opening when viewed in the thickness direction is exposed.

[0021] In the third step of the manufacturing method, the negative resist located in the third opening can be reliably exposed while the portion of the terminal located around the third opening when viewed in the thickness direction is supported by the metal supporting layer.

[0022] The present invention [5] is based on the manufacturing method of the wiring circuit substrate described in [4], and the manufacturing method also includes a seventh step, in which 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 seventh step (a) is implemented after the second step and before the third step, or (b) is implemented simultaneously with the third step, or (c) is implemented after the third step and before the fourth step. In the seventh step, the photomask is arranged on one side in the thickness direction of the terminal in the following manner: when viewed in the thickness direction, the two end edges of the light-shielding portion in the first direction in which the terminal extends are located on the inner side of the second opening and the inner side of the third opening, and each of the two end edges of the light-shielding portion in the second direction intersecting the first direction is located on the outside relative to each of the two end edges of the terminal in the second direction.

[0023] In this manufacturing method, both end edges of the unexposed portion of the negative resist in the first direction can be positioned inside the second opening and inside the third opening. Therefore, both end edges of the conductive member in the first direction can be positioned inside the second opening and inside the third opening. As a result, the conductive member can be reliably formed on the inner portion of the terminal in the first direction.

[0024] Furthermore, even if the photomask is arranged on one side of the terminal in the thickness direction in the seventh step so that each of the two end edges of the light shielding portion in the second direction is located outside each of the two end edges of the terminal in the second direction, the two end edges of the unexposed portion of the negative resist in the second direction can be made to coincide with the two end edges of the terminal in the second direction in the third step. Therefore, the conductive member can be reliably formed across the two end edges of the terminal in the second direction.

[0025] The present invention [6] is based on the manufacturing method of the wiring circuit substrate described in [4], and the manufacturing method also includes a seventh step, in which 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 seventh step (a) is performed after the second step and before the third step, or (b) is performed simultaneously with the third step, or (c) is performed after the third step and before the fourth step. In the seventh step, the photomask is arranged on one side in the thickness direction of the terminal in the following manner: when viewed in the thickness direction, the light-shielding portion is on the first side of the terminal extending in the first direction. One end edge facing upward is located on the inner side of the second opening and the inner side of the third opening, the other end edge of the light-shielding portion in the first direction is located on the outer side of the second opening, and each of the two end edges of the light-shielding portion in the second direction intersecting the first direction is located on the outer side relative to each of the two end edges of the terminal in the second direction, the wiring circuit substrate has a mounting area for mounting electronic components, and in the seventh step, the photomask is arranged on one side in the thickness direction of the terminal in such a manner that the other end edge of the light-shielding portion in the first direction is located on the opposite side of the mounting area relative to the one end edge of the light-shielding portion.

[0026] In the seventh step of the manufacturing method, one edge of the unexposed portion of the negative resist in the first direction can be positioned inside the second opening and inside the third opening. Therefore, one edge of the conductive member in the first direction can be positioned inside the second opening and inside the third opening. Therefore, one end of the conductive member in the first direction can be formed at the inner portion of the terminal.

[0027] On the other hand, since the other end edge of the light shielding portion in the first direction is located outside the second opening, the other end edge of the unexposed portion of the negative resist in the first direction can be located outside the second opening. Therefore, the other end 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.

[0028] Furthermore, when the electronic component is mounted in the mounting area, the electronic component can be located near one end edge in the first direction of the conductive member. At one end portion in the first direction of the conductive member, both ends in the second direction of the electronic component coincide with both ends in the second direction of the conductive member, and at the other end portion in the first direction of the conductive member, both ends in the second direction of the electronic component are located outside relative to both ends in the second direction of the conductive member. At one end portion in the first direction of the conductive member, even when the conductive member melts and contacts the electronic component, short circuits between adjacent conductive members can be effectively suppressed.

[0029] The present invention [7] is the method for manufacturing a wired circuit board according to [1] or [2], wherein the insulating layer has light transmissivity.

[0030] Effects of the Invention

[0031] According to the present invention, a printed circuit board including a conductive member having excellent connection reliability can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a plan view of a printed circuit board manufactured by the manufacturing method according to one embodiment of the present invention.

[0033] Figure 2A to Figure 2C yes Figure 1 An enlarged view of the conductive member of the wiring circuit board shown. Figure 2A It is a top view. Figure 2B It is along Figure 2A Cross-sectional view of line XX. Figure 2C It is along Figure 2A Cross-sectional view of line YY.

[0034] Figure 3A to Figure 3C This is a diagram of the manufacturing process of a wiring circuit board. Figure 2B The right side picture corresponds to Figure 2C correspond. Figure 3A This is a preparatory step including the first step. Figure 3B This is a step of forming the second opening and the third opening. Figure 3C It is the 2nd and 3rd steps.

[0035] Figure 4A to Figure 4C is with Figure 3C The following is a diagram of the manufacturing process. Figure 2B The corresponding manufacturing process diagram. Figure 2C Corresponding manufacturing process diagram. Figure 4A It is the 7th step. Figure 4B It is the fourth step. Figure 4C It is the fifth step.

[0036] Figure 5This is the seventh step in the third variant.

[0037] Figure 6A to Figure 6C This is an enlarged view of the terminal of the second modified example. Fig. 6A It is a top view. Figure 6B It is along Fig. 6A Cross-sectional view of line XX. Figure 6C It is along Fig. 6A Cross-sectional view of line YY.

[0038] FIG. 7A to FIG. 7D This is a manufacturing process diagram of the fourth variant. Fig. 7A This is the third process. Figure 7B This is the 7th process. Figure 7C This is the fourth step. Fig.7D This is the 5th process.

[0039] Figure 8 It is an enlarged top view of the conductive component of the fifth modification.

[0040] Fig. 9 It is a cross-sectional view of the conductive member of the sixth modification example along the second direction.

[0041] Fig.10 It is a cross-sectional view along the second direction of the conductive component of the seventh modification.

[0042] Description of Reference Numerals

[0043] 1. Wiring circuit substrate; 2. Metal supporting layer; 21. Third opening; 3. Base insulating layer (an example of insulating layer); 31. Second opening; 34A, 34B, edge; 4. Conductor layer; 41. Terminal; 411AE, 411BE, edge; 412. Middle part (a part of terminal); 4122A, 4122B, edge; 5. Cover insulating layer; 6. Conductive member; 62A, 62B, edge; 63A, 63B, edge; 7B, second negative resist; 72. Unexposed part; 74. First opening; 75. Resist; 8. Photomask; 81. Transparent part; 82. Light-shielding part; 821A, 821B, edge (light-shielding part in the first direction); 822A, 822B, edge (light-shielding part in the second direction); 9. Electronic component; 114. Through hole. DETAILED DESCRIPTION

[0044] (One embodiment)

[0045] Reference Figure 1 to Figure 2CA wiring circuit board 1 manufactured by one embodiment of the present invention is described. The wiring circuit board 1 has a thickness. The wiring circuit board 1 has a sheet shape. The wiring circuit board 1 extends in a first direction. The first direction is orthogonal to the thickness direction. The wiring 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 arranged on one side of the intermediate portion 13 in the first direction. The first portion 11 is arranged on the other side of the intermediate portion 13 in the first direction.

[0046] The first portion 11 is arranged at the other end portion in the first direction of the wiring circuit board 1. The first portion 11 has a substantially 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 wiring circuit board 1 includes the mounting area 111.

[0047] The mounting region 111 is disposed at the center of the first portion 11 in the first direction. The mounting region 111 is disposed at the center of the first portion 11 in the second direction. The second direction is orthogonal to the thickness direction. The second direction intersects the first direction. The second direction is preferably orthogonal to the first direction.

[0048] The wiring arrangement region 112 is arranged at the peripheral end portion of the first portion 11. The wiring arrangement region 112 is arranged around the mounting region 111. The wiring arrangement region 112 has a substantially rectangular frame shape in a plan view.

[0049] The terminal arrangement region 113 is arranged between the mounting region 111 and a portion of the wiring arrangement region 112 arranged on the other side in the first direction. The terminal arrangement region 113 extends in the second direction.

[0050] 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.

[0051] The second portion 12 is disposed at one end portion of the wired circuit board 1 in the first direction.

[0052] The intermediate portion 13 is disposed in the first direction between the first portion 11 and the second portion 12. The intermediate portion 13 connects the first portion 11 and the second portion 12 in the first direction.

[0053] like Figure 2C As shown, 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 , an insulating cover layer 5 , and a conductive member 6 .

[0054] The metal supporting layer 2 is disposed in the first portion 11, the second portion 12, and the middle 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 the present embodiment, the third opening 21 has a substantially 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.

[0055] Examples of the material of the metal supporting layer 2 include metals. Examples of the metal include stainless steel and copper alloys. The thickness of the metal supporting layer 2 is, for example, not less than 10 μm and not more than 300 μm.

[0056] The base insulating layer 3 is disposed on one side of the metal supporting layer 2 in the thickness direction. In other words, the metal supporting layer 2 is disposed on the other side of the metal supporting layer 2 in the thickness direction. The base insulating layer 3 is disposed in the first portion 11, the second portion 12, and the intermediate portion 13. The base insulating layer 3 in the first portion 11 has a second opening 31.

[0057] The second opening 31 is formed in the first portion 11. In the present embodiment, the second opening 31 has a substantially rectangular shape when viewed from above. The second opening 31 and the third opening 21 together form the through hole 114. The third opening 21 overlaps with the second opening 31 when viewed in the thickness direction. The inner peripheral surface that defines the second opening 31 and the inner peripheral surface that defines the third opening 21 are continuous in the thickness direction.

[0058] 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 arranged in a region other than the thin portion 33. The thin portion 33 is arranged near one side in the first direction of the second opening 31. The base insulating layer 3 has flexibility.

[0059] As a material of the base insulating layer 3, for example, a resin can be cited. As a resin, polyimide can be cited. In the present embodiment, the resin contains a light absorbing component. Therefore, the base insulating layer 3 has a light shielding 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. In addition, the transmittance of the base insulating layer 3 at a wavelength of 300 to 400 nm is, for example, 0% or more.

[0060] The thickness of the base insulating layer 3 is, for example, not less than 1 μm and not more than 20 μm. The thickness of the thick wall portion 32 is, for example, not less than 5 μm and not more than 20 μm. The thickness of the thin wall portion 33 is, for example, not less than 1 μm and not more than 15 μm. The ratio of the thickness of the thin wall portion 33 to the thickness of the thick wall portion 32 is, for example, not more than 80%, preferably not more than 50%, and for example, not less than 5%, preferably not less than 15%.

[0061] like Figure 2CAs shown in FIG. 1 , the conductor layer 4 is disposed on one side of the base insulating layer 3 in the thickness direction. Figure 1 As shown, the conductor layer 4 is disposed in the first portion 11, the second portion 12, and the 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.

[0062] The terminal 41 is arranged in the terminal arrangement area 113. A plurality of terminals 41 are arranged in parallel with each other at intervals in the second direction. Each of the plurality of terminals 41 extends along the first direction. Figure 2A As shown in FIG. 1 , the terminal 41 has a rectangular shape that is long in the first direction when viewed from above. The terminal 41 spans the through hole 114. Figure 2C As shown, the terminal 41 is arranged on one side in the thickness direction of the base insulating layer 3 (thin wall portion 33 ).

[0063] The terminal 41 includes, in the first direction, one end 411A disposed at one end of the terminal 41, another end 411B disposed at the other end of the terminal 41, and an intermediate portion 412 connecting the one end 411A and the other end 411B. The two ends 411A and 411B (one end 411A and the other end 411B) in the first direction of the terminal 41 are disposed on a surface on one side of a portion of the base insulating layer 3 located on both outer sides in the first direction of the third opening 21. That is, the two ends 411A and 411B in the first direction of the terminal 41 are in contact with a surface on one side in the thickness direction of the base insulating layer 3. Each of the two end edges 411AE and 411BE in the first direction of the terminal 41 is located on both outer sides of the third opening 21.

[0064] The middle portion 412 of the terminal 41 in the first direction is located in the through hole 114 when viewed from above. The middle 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 middle portion 412 of the terminal 41 when viewed in the thickness direction. In addition, the middle portion 412 is arranged on one side in the thickness direction of the base insulating layer 3 (thin-walled portion 33).

[0065] like Figure 1 As shown, the second terminal 42 is arranged on the second portion 12. The second terminal 42 is arranged on one surface in the thickness direction of the base insulating layer 3. A plurality of second terminals 42 are arranged at intervals from each other.

[0066] The wiring 43 is arranged in the wiring arrangement area 112 at the middle portion 13 and the first portion 11. The wiring 43 is arranged on one side of the surface in the thickness direction of the base insulating layer 3. The wiring 43 connects the terminal 41 and the second terminal 42. In the first portion 11, the wiring 43 is led in the wiring arrangement area 112 in a manner of bypassing the mounting area 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.

[0067] The thickness of the conductor layer 4 is, for example, not less than 3 μm and not more than 30 μm.

[0068] The width (length in the second direction) of the terminal 41 is, for example, less than 30 μm, further less than 20 μm, further less than 15 μm, further less than 10 μm, and for example, more than 3 μm. The spacing between adjacent terminals 41 in the second direction is, for example, less than 20 μm, further less than 15 μm, further less than 10 μm, and for example, more than 3 μm. If the width and / or spacing of the terminal 41 is below the above upper limit, the terminal 41 can be arranged at a high density, and on the other hand, the terminal 41 is easily short-circuited via the molten conductive member 6. However, in the present embodiment, as described above, since the conductive member 6 can be reliably formed only on the surface of one side of the terminal 4, the terminal 41 can be arranged at a high density and the short circuit of the terminal 41 can be suppressed.

[0069] As a material of the conductor layer 4, for example, a conductor can be cited. As a conductor, for example, copper can be cited. In addition, a protective plating layer (not shown) can also be arranged on the surface of the terminal 41. As a material of the protective plating layer, for example, nickel and gold can be cited.

[0070] The cover insulating layer 5 is disposed on the first portion 11, the second portion 12 and the middle portion 13. Figure 2C As shown, the cover insulating layer 5 is disposed on one surface in the thickness direction of the base insulating layer 3. 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.

[0071] like Figure 2A As shown, the conductive member 6 is arranged in the terminal arrangement area 113. A plurality of conductive members 6 are provided corresponding to the plurality of terminals 41. Figure 2C As shown in FIG. 4 , the conductive member 6 is disposed on one side of the terminal 41 in the thickness direction. More specifically, Figure 2B As shown in FIG. 1 , the conductive member 6 is disposed on one side of the middle portion 412 in the thickness direction. On the other hand, the conductive member 6 is not disposed on both side surfaces of the middle portion 412 (terminal 41) in the second direction. Figure 2AAs shown, the conductive member 6 has a rectangular flat plate shape when viewed from above. Figure 2B As shown in FIG. 1 , each of the two side surfaces 61A and 61B in the second direction of the conductive member 6 is continuous with each of the two side surfaces 4121A and 4121B in the second direction of the intermediate portion 412. That is, each of the two end edges 62A and 62B in the second direction of the conductive member 6 coincides with each of the two end edges 4122A and 4122B in the second direction of the intermediate portion 412 when viewed in the thickness direction.

[0072] like Figure 2C As shown, both end edges 63A and 63B of the conductive member 6 in the first direction are arranged inside the through hole 114 in the first direction. Specifically, both end edges 63A and 63B of the conductive member 6 in the first direction are arranged inside the third opening 21 and the second opening 31 in the first direction.

[0073] 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 thickness of the conductive member 6 is, 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 above the lower limit, the connection reliability with the electronic element 9 described later can be improved. If the thickness of the conductive member 6 is below the upper limit, the short circuit between adjacent terminals 41 can be effectively suppressed.

[0074] The material of the conductive member 6 may be, for example, any one selected from the group consisting of Sn, SnAg alloy, SnBi alloy, SnCu alloy, and SnCo alloy. 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.

[0075] Next, a method for manufacturing the wired circuit board 1 is described. The method for manufacturing the wired circuit board 1 includes an eighth step, a first step, a second step, a third step, a seventh step, a fourth step, a fifth step, and a sixth step. In the manufacturing method, the eighth step, the first step, the second step, the third step, the seventh step, the fourth step, the fifth step, and the sixth step are sequentially performed. Each step is described below in sequence.

[0076] like Figure 3A As shown in FIG. 1 , in the eighth step, first, the metal supporting layer 2 and the base insulating layer 3 are prepared. For example, the base insulating layer 3 is formed on one side of the thickness direction of the sheet-shaped metal supporting layer 2 by photolithography. The base insulating layer 3 has a thick wall portion 32 and a thin wall portion 33. In the eighth step, the metal supporting layer 2 does not yet have the third opening 21 (see FIG. 1 ). Figure 3B). The base insulating layer 3 does not yet have the second opening 31 (see Figure 3B ).

[0077] like Figure 3A As shown, in the first step, the conductor layer 4 is arranged on one side of the base insulating layer 3 in the thickness direction. In other words, in the first step, the terminal 41 is arranged 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. Next, the cover insulating layer 5 is formed on one side of the base insulating layer 3 by photolithography.

[0078] like Figure 3B As shown, after that, the through hole 114 is formed. In the process of forming the through hole 114, for example, etching or laser processing is used. Specifically, the third opening 21 is formed in the metal supporting layer 2, and then the second opening 31 is formed in the base insulating layer 3. The portion of the thin-walled portion 33 arranged on the other side of the middle 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 middle portion 412 is exposed to the other side in the thickness direction.

[0079] like Figure 3C As shown, next, in the second step, the negative resist 7 is disposed on both sides of the base insulating layer 3 and the conductive layer 4 on one side and the other side. In other words, in the second step, the negative resist 7 is disposed on at least one side of the base insulating layer 3 and the terminal 41 in the thickness direction.

[0080] The negative resist 7 can form an image (pattern) that is cured by exposure and cannot be removed by development. In other words, the exposed portion 71 of the negative resist 7 is cured and cannot be removed by development, and the unexposed portion 72 of the negative resist 7 is uncured and can be removed by development. The exposed portion 71 and the unexposed portion 72 constitute a latent image 73. That is, the negative resist 7 can form a latent image 73 by exposure through a mask.

[0081] In the present embodiment, the negative resist 7 is a dry film resist. The negative resist 7 has a sheet shape extending in the first direction and the second direction. Specifically, the negative resist 7 includes a first negative resist 7A and a second negative resist 7B.

[0082] 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 is in contact with one surface in the thickness direction of the base insulating layer 3 and one surface and side surface in the thickness direction of the conductive layer 4.

[0083] The second negative resist 7B is disposed on the other side in the thickness direction of the base insulating layer 3. In the present embodiment, the second negative resist 7B is in contact with the surface on the other side in the thickness direction of the metal supporting layer 2. A portion of the second negative resist 7B is filled into the through hole 114. The second negative resist 7B located in the through hole 114 is in contact with the surface on the other side of the middle portion 412 of the terminal 41.

[0084] like Figure 3C As shown by the arrow in FIG. 1 , in the third step, the negative resist 7 is exposed from the other side in the thickness direction. At this time, first, the second negative resist 7B is entirely exposed. While the second negative resist 7B is exposed, the metal support layer 2 (and the light-shielding base insulating layer 3) serves as a mask, and the first negative resist 7A located in the second opening 31 and the third opening 21 when viewed in the thickness direction is exposed.

[0085] In the third step, the first negative resist 7A is exposed from the other side in the thickness direction using the middle portion 412 which is a part of the terminal 41 as a mask. Specifically, when the first negative resist 7A located in the second opening 31 and the third opening 21 (through hole 114) is exposed from the other side in the thickness direction, the middle portion 412 blocks the light, and an unexposed portion 72 is formed in the first negative resist 7A. The unexposed portion 72 is the same pattern as the middle portion 412. In addition, the middle portion 412 serves as a mask, and when viewed in the thickness direction, the first negative resist 7A located outside the middle portion 412 (around the middle portion 412) in the through hole 114 is exposed to form an exposed portion 71. The exposed portion 71 is a complementary (inverted) pattern of the middle portion 412. That is, a latent image 73 composed of the above-mentioned exposed portion 71 and the unexposed portion 72 is formed in the first negative resist 7A.

[0086] like Figure 4A As shown, after the third step, the seventh step is performed. In the seventh step, the first negative resist 7A is exposed from one side in the thickness direction via the photomask 8. The photomask 8 has a light-transmitting portion 81 and a light-shielding portion 82. A plurality of light-shielding portions 82 are provided on one photomask 8 corresponding to a plurality of terminals 41 (conductive members 6). As the photomask 8, for example, a glass mask can be cited.

[0087] In the seventh step, the photomask 8 is arranged on one side in the thickness direction of the conductor layer 4 in such a manner that both end edges 821A and 821B of the light shielding portion 82 in the first direction are located inside the second opening 31 and inside the third opening 21 when viewed in the thickness direction ( Figure 4A), each of the two end edges 822A and 822B of the light shielding portion 82 in the second direction is located outside relative to each of the two end edges 4122A and 4122B of the terminal 41 in the second direction ( Figure 4A left side of the diagram).

[0088] like Figure 4A As shown in the left figure, in the 7th process, each of the two end edges 822A and 822B of the light shielding portion 82 in the second direction is located outside relative to each of the two end edges 4122A and 4122B of the terminal 41 in the second direction. Even if the first negative resist 7A is exposed, the unexposed portion 72 formed on the surface on one side in the thickness direction of the middle portion 412 will remain the unexposed portion 72 (unexposed state). On the other hand, the exposed portion 71 formed on the outside of the middle portion 412 overlaps with the two end edges 822A and 822B of the light shielding portion 82 when viewed in the thickness direction. Even if the exposed portion 71 partially includes a portion that becomes unexposed in the 7th process, since the exposed portion 71 has already been exposed in the 3rd process (refer to Figure 3C ) is exposed, so the exposed portion 71 (exposed state) is still maintained. In short, in the seventh step, when the middle portion 412 is observed in a cross section along the second direction, the shape of the latent image 73 of the first negative resist 7A does not change.

[0089] like Figure 4A As shown in the right side figure of , the unexposed portion 72 opposite to the light-transmitting portion 81 becomes the exposed portion 71 by the exposure in the seventh step. That is, the unexposed portion 72 in the third step becomes the newly exposed portion 71 by the seventh step. In short, in the seventh step, when the middle portion 412 is observed in a cross section along the first direction, the shape of the latent image 73 of the first negative resist 7A changes. Specifically, the latent images 73 corresponding to the two end edges 63A and 63B of the conductive member 6 in the first direction are newly formed.

[0090] like Figure 4B As shown in the figure, the fourth step is performed after the seventh step. In other words, the seventh step is performed before the fourth step. In the fourth step, 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 addition, in the fourth step, the second negative resist 7B is the exposed portion 71, so it cannot be removed by development, that is, a pattern is not formed, and the resist 75 is formed in a solid surface. The resist 75 protects the other side surface of the middle portion 412 in the thickness direction and the other side surface of the metal supporting layer 2 in the thickness direction.

[0091] like Figure 4CAs shown, in the fifth step, the conductive member 6 is formed in the first opening 74 of the resist 75. In the present embodiment, in the fifth step, the conductive member 6 is formed by plating. Specifically, the wiring circuit substrate 1B in the process of manufacturing with the resist 75 is immersed in a plating solution. As plating, for example, electroplating or chemical plating can be cited. As plating, electroplating is preferably cited. In electroplating, current is supplied to the conductor layer 4 from a plating lead (not shown) continuous with the conductor layer 4. As a result, the material of the conductive member 6 in the plating solution is precipitated (deposited) on the surface of one side of the terminal 41 in the first opening 74. In the fifth step of the present embodiment, since the conductive member 6 is formed by plating, the resist 75 is a plating-resistant layer.

[0092] Afterwards, if Figure 2B and Figure 2C As shown, in the sixth step, the resist 75 is removed. In the process of removing the resist 75, for example, a stripping liquid is used. As the stripping liquid, for example, an alkali liquid can be cited. As the alkali liquid, for example, an amine stripping liquid or a sodium hydroxide stripping liquid can be cited.

[0093] In this way, the wired circuit board 1 is manufactured.

[0094] Afterwards, if Figure 2A and Figure 2C As shown by the imaginary line, the electronic component 9 is mounted on one surface in the thickness direction of the mounting region 111. Thereafter, the conductive member 6 is reflowed by heating to electrically connect the electrode 91 of the electronic component 9 and the terminal 41.

[0095] (Effects of one embodiment)

[0096] like Figure 3C As shown, in the third step of the manufacturing method, since the first negative resist 7A is exposed from the other side in the thickness direction using the middle portion 412 of the terminal 41 as a mask, the outside of the middle portion 412 of the terminal 41 can be reliably exposed. Therefore, it is possible to suppress the formation of an unexpected unexposed portion 72 outside the middle portion 412 of the terminal 41. In other words, the portion of the first negative resist 7A located in the middle portion 412 of the terminal 41 can be made the unexposed portion 72, and the portion other than the middle portion 412 can be made the exposed portion 71.

[0097] Therefore, it is possible to suppress the conductive member 6 from being formed outside 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.

[0098] As a result, it is possible to manufacture the wired circuit board 1 including the conductive member 6 having excellent connection reliability.

[0099] In the fifth step of the manufacturing method, since the conductive member 6 is formed by plating, the conductive member 6 can be formed in a micro region at once and the thickness can be accurately controlled, so the volume of the conductive member 6 (solder) can be precisely controlled.

[0100] 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 the third step, 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.

[0101] In the third step, the portion (the two end portions 411A and 411B) of the terminal 41 located around the third opening 21 when viewed in the thickness direction is supported by the metal supporting layer 2. The metal supporting layer 2 has a light shielding property and has the third opening 21 overlapping with the middle portion 412 of the terminal 41 and the second opening 31 when viewed in the thickness direction. In the third step, the first negative resist 7A located in 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.

[0102] like Figure 4A As shown in the right figure of FIG. 1 , in the seventh step of the manufacturing method, both end edges 821A and 821B of the light shielding portion 82 in the first direction are located inside the second opening 31 and inside the third opening 21. Therefore, both end edges 821A and 821B of the unexposed portion 72 of the first negative resist 7A in the first direction can be located inside the second opening 31 and inside the third opening 21. As a result, the conductive member 6 can be reliably formed in the inner portion of the terminal 41 in the first direction, that is, the middle portion 412.

[0103] like Figure 4A As shown in the left figure of FIG. 1 , in the seventh step, even if the photomask 8 is arranged on one side of the thickness direction of the terminal 41 in such a manner that each of the two end edges 822A and 822B of the light shielding portion 82 in the second direction is located outside each of the two end edges 4122A and 4122B in the second direction of the terminal 41, the two end edges in the second direction of the unexposed portion 72 of the first negative resist 7A can be made to coincide with the two end edges 4122A and 4122B in the second direction of the terminal 41 in the third step. Therefore, the conductive member 6 can be reliably formed from the end edge 4122A in the second direction of the terminal 41 to the other end edge 4122B.

[0104] (Variation Example)

[0105] In the modification, the same reference numerals are used for the same components and processes as those in the first embodiment, and detailed description thereof is omitted. In addition, the modification can have the same effects as those in the first embodiment except for special descriptions. Furthermore, the first embodiment and its modification can be appropriately combined.

[0106] (First Modification)

[0107] In the fourth step, the conductive member 6 may be formed by coating instead of plating. In the first variant, a paste containing the material of the conductive member 6 is coated on the first negative resist 7A (the first opening 74). Then, the paste is filled in the first opening 74. Thereafter, the paste is dried. In the first variant, the negative resist 7 may include only the first negative resist 7A. In the second step of the first variant, the negative resist 7 may be arranged only on one side of the base insulating layer 3 in the thickness direction.

[0108] (Second Modification)

[0109] Although not shown in the figure, the seventh step may be (a) performed after the second step and before the third step, or (b) performed simultaneously with the third step.

[0110] (Third Modification)

[0111] like Figure 5 As shown, the photomask 8 may be provided with one light shielding portion 82 so as to include the plurality of terminals 41 in the second direction.

[0112] (Fourth Modification)

[0113] Reference Figure 6A to Figure 6C A wired circuit board 1 manufactured by the manufacturing method according to the fourth modification example will be described.

[0114] like Figure 6C As shown, the other side 351 of the inner edge 35 of the base insulating layer 3 defining the second opening 31 is located on one side (inner side) in the first direction relative to the other side 251 of the inner edge 25 of the metal supporting layer 2 defining the third opening 21 .

[0115] like Fig. 6A As shown, the conductive member 6 has a substantially T-shape when viewed from above. Figure 6C As shown, the other end 64 of the conductive member 6 in the first direction is arranged on one side of the thickness direction of the base insulating layer 3. 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. Fig. 6AAs shown, the other end 64 of the conductive member 6 in the first direction has protrusions 65A and 65B. When projected in the thickness direction, the protrusions 65A and 65B protrude toward both outer sides of the terminal 41 in the second direction. Figure 6B As shown, the protrusions 65A and 65B are in contact with one surface of the base insulating layer 3 and the side surface of the other end portion 411B of the terminal 41 .

[0116] like Fig. 7A As shown in FIG. 1 , in the third step, the first negative resist 7A disposed on one side of the base insulating layer 3 is an unexposed portion 72. That is, the base insulating layer 3 functions as a mask by exposure from the other side in the third step. However, the first negative resist 7A in the second opening 31 also forms an exposed portion 71 in the first negative resist 7A located around the middle portion 412.

[0117] like Figure 7B As shown, in the seventh step, the photomask 8 is arranged on one side in the thickness direction of the terminal 41 in such a manner that 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 inside the third opening 21 ( Figure 7B The other end edge 821B of the light shielding portion 82 is located outside the second opening 31 ( Figure 7B ), each of the two end edges 822A and 822B of the light shielding portion 82 in the second direction is located outside relative to each of the two end edges 4122A and 4122B of the terminal in the second direction ( Figure 7B In the seventh step, the other end edge 821B of the light shielding portion 82 is located in the mounting area 111 relative to the one end edge 821A of the light shielding portion in the first direction (see Fig. 6A and Figure 6C on the opposite side of the imaginary line).

[0118] (Function and Effect of the Fourth Modification)

[0119] like Figure 7B As shown in the right figure of FIG. 1 , in the seventh step of the manufacturing method, one edge of the unexposed portion 72 of the first negative resist 7A in the first direction can be located inside the second opening 31 and inside the third opening 21. Fig.7D As shown in the right side figure of , the first end edge 63A of the conductive member 6 can be located inside the second opening 31 and the third opening 21. Therefore, the first end of the conductive member 6 can be formed inside the terminal 41, that is, the middle portion 412.

[0120] On the other hand, Figure 7BAs shown in the right side figure of FIG. 1 , the other end edge of the unexposed portion 72 of the first negative resist 7A in the first direction can be located outside the second opening 31. Therefore, Fig.7D As shown in the right side figure of FIG. 3 , the other end edge 63B of the conductive member in the first direction is located outside the second opening 31 . As a result, the other end portion of the conductive member 6 in the first direction is formed at the other end portion 411B of the terminal 41 .

[0121] like Fig. 6A and Figure 6C As shown, when the electronic component 9 (imaginary line) is mounted in the mounting area 111, the electronic component 9 can be located near the one end edge 63A in the first direction of the conductive member 6. At the one end edge 63A in the first direction of the conductive member 6, even when the conductive member 6 melts and flows toward the electrode 91 of the electronic component 9 and contacts the electrode 91, short circuits between adjacent conductive members 6 in the first direction can be effectively suppressed.

[0122] (Fifth Modification)

[0123] like Figure 8 As shown, the other end portion 64 of the conductive member 6 may have one protrusion 65A and may not have the other protrusion 65B. The conductive member 6 has a substantially L-shaped shape in a plan view.

[0124] (Sixth Modification, Seventh Modification)

[0125] The base insulating layer 3 may also be light-transmissive. In the third step, the base insulating layer 3 is disposed on the other side of the middle portion 412 of the terminal 41. Light from the other side in the thickness direction passes through the light-transmissive base insulating layer 3, and the middle portion 412 can function as a mask.

[0126] (Sixth Modification)

[0127] like Fig. 9 As shown, the end edges 34A and 34B of the base insulating layer 3 arranged on the other side of the middle portion 412 in the second direction may coincide with the end edges 4122A and 4122B of the middle portion 412 when viewed in the thickness direction.

[0128] (Seventh Modification)

[0129] like Fig.10 As shown, it is also possible that each of the two end edges 34A and 34B in the second direction of the base insulating layer 3 arranged on the surface on the other side of the middle portion 412 is located inner than each of the two end edges 4122A and 4122B of the middle portion 412 when viewed in the thickness direction.

[0130] In addition, the above invention is provided as an exemplary embodiment of the present invention, but this is only an example and the present invention should not be interpreted as being limitative. Modifications of the present invention that are obvious to those skilled in the art are included in the above claims.

[0131] Industrial Applicability

[0132] The method for manufacturing a wired circuit board of the present invention is used for manufacturing a wired circuit board.

Claims

1. A method for manufacturing a wiring circuit substrate, wherein: The wiring circuit substrate comprises: an insulating layer; a terminal arranged on one side in a thickness direction of the insulating layer; and a conductive member disposed on one side of the terminal in the thickness direction, the manufacturing method comprising: a first step of arranging the terminal on one side in a thickness direction of the insulating layer; A second step, in which a negative resist is disposed on at least one side of the insulating layer and the terminal; A third step, in which the negative resist is exposed from the other side in the thickness direction using at least a portion of the terminal as a mask; A fourth step, in which the unexposed portion of the negative resist is removed by development to form a resist having a first opening corresponding to the unexposed portion; a fifth step of forming the conductive member in the first opening of the resist; and In the sixth step, the resist is removed.

2. The method for manufacturing a wired circuit board according to claim 1, wherein: In the second step, the negative resist is arranged on one side and the other side of the insulating layer and the terminal. In the fifth step, the conductive member is formed by plating.

3. The method for manufacturing a wired circuit board according to claim 1 or 2, wherein: The insulating layer has light-shielding properties. The insulating layer has a second opening overlapping at least a portion of the terminal when viewed in the thickness direction, In the third step, the negative resist located in the second opening when viewed in the thickness direction is exposed.

4. The method for manufacturing a wired circuit board according to claim 3, wherein: The wired circuit board further includes a metal supporting layer disposed on the other side of the insulating layer in the thickness direction. The metal supporting layer has a third opening overlapping at least a portion of the terminal and the second opening when viewed in the thickness direction, In the third step, the negative resist located in the third opening when viewed in the thickness direction is exposed.

5. The method for manufacturing a wired circuit board according to claim 4, wherein: The manufacturing method further includes a seventh step 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. The seventh step is performed after the second step and before the third step, or simultaneously with the third step, or after the third step and before the fourth step. In the seventh step, the photomask is arranged on one side in the thickness direction of the terminal in the following manner: when viewed in the thickness direction, the two end edges of the light-shielding portion in the first direction in which the terminal extends are located on the inner side of the second opening and the inner side of the third opening, and each of the two end edges of the light-shielding portion in the second direction intersecting the first direction is located on the outer side relative to each of the two end edges of the terminal in the second direction.

6. The method for manufacturing a wired circuit board according to claim 4, wherein: The manufacturing method further includes a seventh step 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. The seventh step is performed after the second step and before the third step, or simultaneously with the third step, or after the third step and before the fourth step. In the seventh step, the photomask is arranged on one side in the thickness direction of the terminal in the following manner: when viewed in the thickness direction, one end edge of the light shielding portion in the first direction in which the terminal extends is located inside the second opening and inside the third opening, the other end edge of the light shielding portion in the first direction is located outside the second opening, and each of the two end edges of the light shielding portion in the second direction intersecting the first direction is located outside relative to each of the two end edges of the terminal in the second direction. The wiring circuit substrate has a mounting area for mounting electronic components. In the seventh step, the photomask is arranged on one side in the thickness direction of the terminal so that the other end edge of the light shielding portion is located on the opposite side of the mounting region with respect to the one end edge of the light shielding portion in the first direction.

7. The method for manufacturing a wired circuit board according to claim 1 or 2, wherein: The insulating layer is light-transmissive.

Images