Wiring circuit board

Abstract

To provide a wiring circuit board that can reduce the electrical resistance of the wiring. [Solution] The wiring circuit board 1 comprises a wiring section 3A and a first support section 2A that supports one end of the wiring section 3A. The wiring section 3A has a metal support layer 11, a first insulating layer 12, and wiring 133A. The wiring 133A has a first conductor layer 1331 disposed on the first insulating layer 12 and a second conductor layer 1332 that covers the first conductor layer 1331 and is in contact with the first insulating layer 12. The ratio of the thickness T11 of the wiring 133A to the thickness T21 of the first conductor layer 1331 (T11 / T21) is 2.0 or more.

Description

Technical Field

[0001] The present invention relates to a wiring circuit board.

Background Art

[0002] Conventionally, a wiring circuit board including a plurality of wiring bodies arranged in parallel at intervals from each other is known (see, for example, Patent Document 1 below). The wiring body has a wiring (main wiring portion).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a wiring circuit board as described in Patent Document 1, for example, when it is desired to increase the current flowing through the wiring (main wiring portion), there may be a case where it is desired to reduce the electrical resistance of the wiring.

[0005] The present invention provides a wiring circuit board capable of reducing the electrical resistance of wiring.

Means for Solving the Problems

[0006] The present invention [1] includes a wiring portion and a support portion that supports one end portion of the wiring portion, the wiring portion having a metal support layer, an insulating layer disposed on the metal support layer, and a wiring disposed on the insulating layer, and at least in the wiring portion, the wiring having a first conductor layer disposed on the insulating layer and a second conductor layer that covers the first conductor layer and contacts the insulating layer, and a ratio of the thickness of the wiring to the thickness of the first conductor layer being 2.0 or more.

[0007] The present invention [2] includes the wiring circuit board described in [1] above, wherein the ratio of the thickness of the first conductor layer to the width of the first conductor layer is 0.3 or more and 1.1 or less.

[0008] The present invention [3] includes the wiring circuit board of the above [1] or [2], wherein the width of the wiring is greater than the width of the first conductor layer.

[0009] The present invention [4] includes any one of the wiring circuit boards described in [1] to [3] above, wherein the distance between each of the two sides of the wiring and the first conductor layer in the width direction of the wiring is 10.00 μm or more.

[0010] The present invention [5] includes any one of the wiring circuit boards described in [1] to [4] above, wherein the wiring has a central portion and an end portion in the width direction of the wiring, and the central portion protrudes in the thickness direction toward the opposite side of the metal support layer relative to the insulating layer compared to the end portion.

[0011] The present invention [6] includes any one of the above [1] to [5] wiring circuit boards, wherein the wiring has recesses on each of the two sides in the width direction of the wiring, and the depth of the recesses is 0.7 μm or less.

[0012] The present invention [7] includes any one of the above [1] to [6] wiring circuit boards, wherein the support portion has wiring that is continuous with the wiring portion, and the wiring portion of the support portion has the first conductor layer and the second conductor layer.

[0013] The present invention [8] includes any one of the above [1] to [7] wiring circuit boards, wherein the wiring circuit board has a plurality of wiring sections spaced apart from each other, and the support section supports one end of each of the plurality of wiring sections. [Effects of the Invention]

[0014] According to the wiring circuit board of the present invention, at least in the wiring portion, the wiring has a first conductor layer and a second conductor layer.

[0015] The second conductor layer covers the first conductor layer and is in contact with the insulating layer. Therefore, compared to the case where the wiring is formed from the first conductor layer alone, the second conductor layer can increase both the width and thickness of the wiring.

[0016] As a result, the cross-sectional area of ​​the wiring can be increased, thereby reducing the electrical resistance of the wiring.

[0017] Here, the second conductor layer can be formed by plating and growing it in both the width and thickness directions, using the first conductor layer as a seed. In this case, plating growth in the width direction may be inhibited by the plating resist, resulting in the formation of recesses (parts where plating growth is inhibited) on the sides of the wiring.

[0018] If excessively deep recesses are formed on the sides of the wiring, the electrical resistance of the wiring may increase due to these recesses, potentially preventing sufficient reduction of the wiring's electrical resistance.

[0019] In this regard, the ratio of the wiring thickness to the thickness of the first conductor layer is 2.0 or greater.

[0020] Therefore, the depth of the recess can be reduced, and the electrical resistance of the wiring can be reduced more reliably. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is a plan view of a wiring circuit board as one embodiment of the present invention. Note that the second insulating layer is omitted in Figure 1. [Figure 2] Figure 2A is a cross-sectional view AA of the wiring circuit board shown in Figure 1. Figure 2B is a cross-sectional view BB of the wiring circuit board shown in Figure 1. [Figure 3] Figures 3A and 3B are process diagrams illustrating the manufacturing method of a wiring circuit board. Figure 3A shows the first insulating layer formation process. Figure 3B shows the first conductive layer formation process. [Figure 4]FIG. 4A and FIG. 4B are process diagrams for explaining a method of manufacturing a wiring circuit board, following FIG. 3B. FIG. 4A shows a second conductive layer forming step. FIG. 4B shows a second insulating layer forming step. [Figure 5] FIG. 5 shows a wiring circuit board of a modified example.

MODE FOR CARRYING OUT THE INVENTION

[0022] 1. Wiring Circuit Board As shown in FIG. 1, the wiring circuit board 1 includes a plurality of support portions 2 (in this embodiment, a first support portion 2A and a second support portion 2B) and a plurality of wiring portions 3A, 3B.

[0023] The first support portion 2A and the second support portion 2B are arranged at intervals from each other. The shapes of the first support portion 2A and the second support portion 2B are not limited. The first support portion 2A supports one end portion of each of the wiring portions 3A, 3B. Terminals 131A, 131B of a conductor pattern 13 described later may be arranged on the first support portion 2A. The second support portion 2B supports the other end portion of each of the wiring portions 3A, 3B. Terminals 132A, 132B of the conductor pattern 13 described later may be arranged on the second support portion 2B.

[0024] The wiring sections 3A and 3B are positioned between the first support section 2A and the second support section 2B. At least a portion of the wiring 133A, which will be described later, is positioned in the wiring section 3A. The wiring section 3A has a width in the width direction of the wiring 133A (the wiring 133A of the wiring section 3A) and extends in the direction in which the wiring 133A (the wiring 133A of the wiring section 3A) extends. The width direction is perpendicular to the thickness direction of the wiring circuit board 1. The direction in which the wiring 133A extends is perpendicular to both the width direction and the thickness direction. At least a portion of the wiring 133B, which will be described later, is positioned in the wiring section 3B. The wiring section 3B has a width in the width direction of the wiring 133B (the wiring 133B of the wiring section 3B) and extends in the direction in which the wiring 133B (the wiring 133B of the wiring section 3B) extends. In this embodiment, the wiring section 3B extends in the same direction as the wiring section 3A. One end of each wiring section 3A and 3B is connected to the first support section 2A. The other end of each wiring section 3A and 3B is connected to the second support section 2B. The shape of each wiring section 3A and 3B is not limited. Each wiring section 3A and 3B may be straight or curved. In this embodiment, the wiring 133A and 133B are arranged in the width direction of the wiring 133A. The wiring sections 3A and 3B are arranged with a distance D between them in the width direction of the wiring 133A.

[0025] The distance D between wiring section 3A and wiring section 3B is, for example, 5 μm to 300 μm, preferably 10 μm to 250 μm.

[0026] As shown in Figures 2A and 2B, the wiring circuit board 1 has a metal support layer 11, a first insulating layer 12 as an example of an insulating layer, a conductor pattern 13, and a second insulating layer 14.

[0027] (1) Metal support layer The metal support layer 11 is placed in the support section 2 (first support section 2A and second support section 2B) and the wiring sections 3A and 3B. In other words, the wiring sections 3A and 3B have the metal support layer 11. The metal support layer 11 supports the first insulating layer 12, the conductor pattern 13, and the second insulating layer 14. The metal support layer 11 is made of metal. Examples of materials for the metal support layer 11 include copper, nickel, cobalt, iron, and alloys thereof. Examples of alloys include stainless steel and copper alloys. Preferably, the material for the metal support layer 11 is a copper alloy.

[0028] The thickness T1 of the metal support layer 11 is, for example, 10 μm to 300 μm, preferably 50 μm to 250 μm.

[0029] As shown in Figure 2A, in the wiring section 3A, the width W1 of the metal support layer 11 is, for example, 5 μm to 300 μm, preferably 10 μm to 250 μm.

[0030] In the wiring section 3A, the ratio (T1 / W1) of the thickness T1 of the metal support layer 11 to the width W1 of the metal support layer 11 is 2 or more, preferably 5 or more. If the ratio (T1 / W1) is greater than or equal to the lower limit value above, the rigidity of the wiring section 3A in the thickness direction can be ensured. The ratio (T1 / W1) is, for example, 30 or less, preferably 10 or less. The ratio (T1 / W1) may be 2 to 30, or 5 to 10.

[0031] (2) First insulating layer The first insulating layer 12 is placed on the support portion 2 (first support portion 2A, second support portion 2B) and the wiring portions 3A, 3B. In other words, the wiring portions 3A, 3B have the first insulating layer 12. The first insulating layer 12 is placed on one side of the metal support layer 11 in the thickness direction of the metal support layer 11. The first insulating layer 12 is placed on the metal support layer 11.

[0032] The first insulating layer 12 may be placed on the metal support layer 11 via a protective metal layer (first protective metal layer). In other words, the wiring circuit board 1 may include a protective metal layer placed between the metal support layer 11 and the first insulating layer 12 in the thickness direction. The protective metal layer protects the metal support layer 11. The protective metal layer is, for example, a sputtering layer placed on one side surface of the metal support layer 11 in the thickness direction. Examples of materials for the protective metal layer include chromium, copper, nickel, titanium, and alloys thereof.

[0033] The first insulating layer 12 is positioned between the metal support layer 11 and the conductor pattern 13 in the thickness direction. The first insulating layer 12 insulates the metal support layer 11 from the conductor pattern 13. The first insulating layer 12 is made of a resin. Examples of resins include polyimide, maleimide, epoxy resin, polybenzoxazole, and polyester.

[0034] (3) Conductor pattern The conductor pattern 13 is positioned on one side of the first insulating layer 12 in the thickness direction. The conductor pattern 13 is positioned on the first insulating layer 12. In other words, the wirings 133A and 133B are positioned on the first insulating layer 12.

[0035] The conductor pattern 13 may be arranged on the first insulating layer 12 via a protective metal layer (second protective metal layer). In other words, the wiring circuit board 1 may include a protective metal layer disposed between the first insulating layer 12 and the conductor pattern 13 in the thickness direction. The protective metal layer protects the conductor pattern 13. The protective metal layer is, for example, a sputtering layer disposed on one side surface of the first insulating layer 12 in the thickness direction. Examples of materials for the protective metal layer include chromium, copper, nickel, titanium, and alloys thereof.

[0036] The conductor pattern 13 is positioned in the thickness direction on the opposite side of the metal support layer 11 from the first insulating layer 12. The shape of the conductor pattern 13 is not limited.

[0037] As shown in Figure 1, the conductor pattern 13 has, for example, a plurality of terminals 131A, 131B, a plurality of terminals 132A, 132B, and a plurality of wires 133A, 133B.

[0038] Terminals 131A and 131B are positioned on the first support portion 2A. Each of terminals 131A and 131B has a corner land shape. Terminal 131B is positioned away from terminal 131A.

[0039] Terminals 132A and 132B are positioned on the second support portion 2B. Each of terminals 132A and 132B has a corner land shape. Terminal 132B is positioned away from terminal 132B.

[0040] Each of the terminals 131A, 131B, 132A, and 132B has a first conductor layer 1311 and a second conductor layer 1312.

[0041] The first conductor layer 1311 is positioned between the first insulating layer 12 and the second conductor layer 1312 in the thickness direction. The first conductor layer 1311 is positioned on top of the first insulating layer 12. The first conductor layer 1311 is made of a metal. Examples of metals include copper, silver, gold, iron, aluminum, chromium, and alloys thereof. To obtain good electrical properties, copper is preferably used as the metal.

[0042] The second conductor layer 1312 is positioned on one side of the first conductor layer 1311 in the thickness direction. The second conductor layer 1312 is positioned on the first conductor layer 1311. The second conductor layer 1312 does not come into contact with the first insulating layer 12. The second conductor layer 1312 is made of a metal. The same metal as the first conductor layer 1311 is an example of the metal used. Preferably, the second conductor layer 1312 is made of the same metal as the first conductor layer 1311.

[0043] Wiring 133A electrically connects terminals 131A and 132A. One end of wiring 133A is connected to terminal 131A. The other end of wiring 133A is connected to terminal 132A. At least a portion of wiring 133A is located in wiring section 3A. In other words, wiring section 3A has wiring 133A. One end of wiring 133A may be located in the first support section 2A. The other end of wiring 133A may be located in the second support section 2B. In other words, support section 2 may have a portion of wiring 133A. Wiring 133A in support section 2 is continuous with wiring 133A in wiring section 3A.

[0044] Wiring 133B electrically connects terminals 131B and 132B. One end of wiring 133B is connected to terminal 131B. The other end of wiring 133B is connected to terminal 132B. At least a portion of wiring 133B is located in wiring section 3B. In other words, wiring section 3B has wiring 133B. One end of wiring 133B may be located in the first support section 2A. The other end of wiring 133B may be located in the second support section 2B. In other words, support section 2 may have a portion of wiring 133B. Wiring 133B in support section 2 is continuous with wiring 133B in wiring section 3A.

[0045] The direction in which the wiring 133A and 133B of the support section 2 extend is not limited. The wiring 133A and 133B of the support section 2 may extend in a direction that intersects with the direction in which the wiring 133A of the wiring section 3A extends.

[0046] (1-4) Second insulating layer As shown in Figures 2A and 2B, the second insulating layer 14 is positioned on one side of the first insulating layer 12 in the thickness direction. The second insulating layer 14 is positioned on the first insulating layer 12. The second insulating layer 14 covers all the wiring 133A and 133B. However, the second insulating layer 14 does not cover the terminals 131A, 131B, 132A, and 132B. The second insulating layer 14 is made of resin. Examples of resins include polyimide, maleimide, epoxy resin, polybenzoxazole, and polyester.

[0047] 2. Wiring Details Next, with reference to Figure 2A, the details of wiring 133A will be explained. Note that wiring 133B has the same structure as wiring 133A. The explanation of wiring 133B will be omitted.

[0048] Wiring 133A has a central portion C and an end portion E in the width direction. The central portion C is located in the center of wiring 133B in the width direction. The central portion C protrudes toward one side in the thickness direction compared to the end portion E. In other words, the central portion C protrudes toward the opposite side of the metal support layer 11 relative to the first insulating layer 12 in the thickness direction compared to the end portion E. One end face S1 of wiring 133A in the thickness direction has a substantially arc shape. Both side surfaces S2 and S3 of wiring 133A in the width direction extend in the thickness direction.

[0049] The width W11 of the wiring 133A is, for example, 30 μm or more, preferably 35 μm or more. The width W11 of the wiring 133A is, for example, 50 μm or less, preferably 45 μm or less.

[0050] The thickness T11 of the central part C of the wiring 133A is, for example, 30 μm or more, preferably 35 μm or more. The thickness T11 of the central part C of the wiring 133A is, for example, 50 μm or less, preferably 45 μm or less.

[0051] The ratio (T11 / W11) of the thickness T11 of the central part C to the width W11 of the wiring 133A is, for example, 3.0 or less, preferably 2.0 or less, more preferably 1.7 or less, and more preferably 1.3 or less. If the ratio (T11 / W11) is below the above upper limit, it is possible to suppress an excessive increase in the rigidity of the wiring 133A in the thickness direction. The ratio (T11 / W11) is, for example, 0.1 or more, preferably 0.3 or more, more preferably 0.5 or more, and more preferably 0.8 or more. If the ratio (T11 / W11) is above the above lower limit, it is possible to increase the rigidity of the wiring 133A in the thickness direction relative to the rigidity of the wiring 133A in the width direction. The ratio (T11 / W11) may be 0.1 to 3.0, 0.3 to 2.0, 0.5 to 1.7, or 0.8 to 1.3.

[0052] The difference ΔT between the thickness T11 of the central part C and the thickness T12 of the end part E is, for example, 10% or more, preferably 20% or more, and more preferably 25% or more of the thickness T11 of the central part C. The percentage of "difference ΔT between the thickness T11 of the central part C and the thickness T12 of the end part E" relative to the thickness T11 of the central part C is defined as the protrusion rate of the central part C. If the protrusion rate of the central part C is greater than or equal to the above lower limit, the rigidity of the wiring in the thickness direction can be reliably increased. The protrusion rate of the central part C is, for example, 70% or less, preferably 60% or less, and more preferably 55% or less. If the protrusion rate of the central part C is less than or equal to the above upper limit, the wiring cross-sectional area can be secured, and the electrical resistance of the wiring 133A can be reduced. The protrusion rate of the central part C may be 10% to 70%, 20% to 60%, or 25% to 55%.

[0053] Furthermore, the wiring 133A has recesses 1330 on both sides S2 and S3 in the width direction. The recess 1330 on one side S2 in the width direction is recessed toward the other side in the width direction. The recess 1330 on the other side S3 in the width direction is recessed toward the one side in the width direction. The recesses 1330 on side S2 and side S3 are recessed toward the first conductor layer 1331, which will be described later, in the width direction.

[0054] The depth D1 of the recess 1330 is, for example, 0.7 μm or less, preferably 0.5 μm or less. If the depth D1 of the recess 1330 is less than or equal to the above upper limit, an excessive reduction in the cross-sectional area of ​​the wiring can be suppressed, and the electrical resistance of the wiring 133A can be reduced. The depth D1 of the recess 1330 is, for example, 0.01 μm or more, preferably 0.05 μm or more. If the depth D1 of the recess 1330 is greater than or equal to the above lower limit, the second insulating layer 14 can penetrate into the recess 1330, thereby suppressing the peeling of the second insulating layer 14.

[0055] The wiring 133A of the wiring section 3A has a first conductor layer 1331 and a second conductor layer 1332. As shown in Figure 2B, the wiring 133A of the support section 2 may also have a first conductor layer 1331 and a second conductor layer 1332. In this embodiment, the wiring 133A consists of a first conductor layer 1331 and a second conductor layer 1332.

[0056] (1) First conductor layer As shown in Figure 2A, the first conductor layer 1331 is positioned on one side of the first insulating layer 12 in the thickness direction. The first conductor layer 1331 is positioned on the first insulating layer 12. In the width direction, the first conductor layer 1331 is positioned in the central part C of the wiring 133A. In the width direction, the first conductor layer 1331 is positioned between the recess 1330 on side S2 and the recess 1330 on side S3. The first conductor layer 1331 has a rectangular cross-section. The first conductor layer 1331 is connected to terminal 131A (see Figure 1) and terminal 132A (see Figure 1). The first conductor layer 1331 is made of the same metal as the first conductor layer 1311 of terminal 131A.

[0057] The width W21 of the first conductor layer 1331 is, for example, 1 μm or more, preferably 5 μm or more. The width W21 of the first conductor layer 1331 is, for example, 20 μm or less, preferably 15 μm or less.

[0058] The thickness T21 of the first conductor layer 1331 is, for example, 1 μm or more, preferably 5 μm or more. The thickness T21 of the first conductor layer 1331 is, for example, 20 μm or less, preferably 15 μm or less.

[0059] The ratio (T21 / W21) of the thickness T21 of the first conductor layer 1331 to the width W21 of the first conductor layer 1331 is, for example, 0.3 or more, preferably 0.4 or more. If the ratio (T21 / W21) is greater than or equal to the lower limit value above, the protrusion ratio of the central part C of the second conductor layer 1332 can be increased, and the rigidity of the wiring in the thickness direction can be increased. The ratio (T21 / W21) is, for example, 1.1 or less, preferably 0.5 or less. If the ratio (T21 / W21) is less than or equal to the upper limit value above, the depth of the recesses 1330 on the sides S2 and S3 can be reduced.

[0060] (2) Second conductor layer The second conductor layer 1332 is positioned on one side of the first insulating layer 12 in the thickness direction. The second conductor layer 1332 covers the first conductor layer 1331. More specifically, the second conductor layer 1332 covers all of one side in the thickness direction and both sides in the width direction of the first conductor layer 1331. The second conductor layer 1332 is positioned on the first insulating layer 12. The second conductor layer 1332 is in contact with the first insulating layer 12. The second conductor layer 1332 is made of the same metal as the second conductor layer 1312 of terminal 131A (see Figure 1).

[0061] In the wiring section 3A, the ratio (T11 / T21) of the thickness T11 of the wiring 133A to the thickness T21 of the first conductor layer 1331 is 2.0 or greater, preferably 2.3 or greater. If the ratio (T11 / T21) is greater than or equal to the lower limit value above, the depth of the recesses 1330 on the sides S2 and S3 can be reduced. The upper limit value of the ratio (T11 / T21) is not limited. The ratio (T11 / T21) may be 6.0 or less, 5.0 or less, or 4.0 or less.

[0062] The width W11 of wiring 133A is greater than the width W21 of the first conductor layer 1331. The ratio of the width W11 of wiring 133A to the width W21 of the first conductor layer 1331 (W11 / W21) is, for example, 1.2 or more, preferably 2.0 or more. If the ratio (W11 / W21) is greater than or equal to the lower limit above, the wiring cross-sectional area can be secured and the electrical resistance of wiring 133A can be reduced. There is no upper limit to the ratio (W11 / W21). The ratio (W11 / W21) is, for example, 3.0 or less.

[0063] In the width direction, the distances D11 and D12 between each of the two sides S2 and S3 of the wiring 133A and the first conductor layer 1331 are, for example, 10.00 μm or more, preferably 10.50 μm or more. If the distances D11 and D12 are greater than or equal to the lower limit, the depth of the recesses 1330 on each of the sides S2 and S3 can be reduced. The distances D11 and D12 are, for example, 15.00 μm or less, preferably 13.00 μm or less. If the distances D11 and D12 are less than or equal to the upper limit, the thickness T11 of the wiring 133A can be ensured.

[0064] 3. Manufacturing method of a wiring circuit board Next, the manufacturing method of the wiring circuit board 1 will be described with reference to Figures 3A to 4B.

[0065] The method for manufacturing the wiring circuit board 1 includes a first insulating layer formation step (see Figure 3A), a first conductor layer formation step (see Figure 3B), a second conductor layer formation step (see Figure 4A), a second insulating layer formation step (see Figure 4B), and an etching step.

[0066] (1) First insulating layer formation process As shown in Figure 3A, in the first insulating layer formation step, a first insulating layer 12 is formed on a metal substrate M. Specifically, a photosensitive resin solution (varnish) is applied to the substrate M and dried. Drying forms a photosensitive resin coating on the substrate M. Next, the photosensitive resin coating is exposed to light and developed. Development forms the first insulating layer 12 on the substrate M in a predetermined pattern.

[0067] (2) First conductor layer formation process Next, as shown in Figure 3B, in the first conductor layer formation step, first conductor layers 1311 (see Figure 1) and 1331 are formed on the first insulating layer 12.

[0068] In more detail, first, a seed layer is formed on the surface of the first insulating layer 12 and the substrate M. The seed layer is formed, for example, by sputtering. Examples of materials for the seed layer include chromium, copper, nickel, titanium, and alloys thereof.

[0069] Next, the plating resist R1 is bonded to the substrate M. The plating resist R1 covers the first insulating layer 12.

[0070] Next, the plating resist R1 is exposed to light while the areas where the first conductor layers 1311 and 1331 are formed are shielded, and the exposed plating resist R1 is developed.

[0071] As a result, the plating resist R1 in the light-shielded areas is removed, and the seed layer is exposed in the areas where the first conductor layers 1311 and 1331 are formed. On the other hand, the plating resist R1 in the exposed areas remains.

[0072] Next, first conductor layers 1311 and 1331 are formed on the exposed seed layer by electroplating.

[0073] After the electrolytic plating is complete, the plating resist R1 is removed.

[0074] (3) Second conductor layer formation process Next, as shown in Figure 4A, in the second conductor layer formation step, second conductor layers 1312 (see Figure 1) and 1332 are formed on the first insulating layer 12.

[0075] In detail, first, the plating resist R2 is bonded to the substrate M. The plating resist R2 covers the first insulating layer 12 and the first conductor layers 1311 and 1331.

[0076] Next, the plating resist R2 is exposed to light while the areas where the second conductive layers 1312 and 1332 are formed are shielded, and the exposed plating resist R2 is developed.

[0077] As a result, the plating resist R2 in the light-shielded areas is removed, and the seed layer and the first conductor layers 1311 and 1331 are exposed in the areas where the second conductor layers 1312 and 1332 are formed. On the other hand, the plating resist R2 in the exposed areas remains.

[0078] In the developed plating resist R2, the width W31 of the portion where the second conductive layer 1332 is formed is wider than the width W21 of the first conductive layer 1331. Furthermore, the first conductive layer 1331 is positioned in the center of the portion where the second conductive layer 1332 is formed, in the width direction.

[0079] Next, a second conductor layer 1332 is formed on the exposed seed layer and the first conductor layer 1331 by electroplating, and a second conductor layer 1312 is formed on the first conductor layer 1311.

[0080] The formation of the second conductor layers 1312 and 1332 completes the wiring 133A and 133B, and the terminals 131A, 132A, 131B, and 132B described above. In the width direction, the second conductor layer 1332 is laminated on top of the first conductor layer 1331 at the central portion C of each of the wirings 133A and 133B. On the other hand, at both ends E of each of the wirings 133A and 133B in the width direction, the second conductor layer 1332 is formed on top of the first insulating layer 12. Due to the placement of the first conductor layer 1331, the central portion C protrudes to one side in the thickness direction compared to the end portion E.

[0081] After electroplating is complete, the plating resist R2 is removed. Subsequently, the seed layer exposed by the removal of the plating resist R2 is removed by etching.

[0082] (4) Second insulating layer formation process Next, as shown in Figure 4B, in the second insulating layer formation step, the second insulating layer 14 is formed on the first insulating layer 12 in the same manner as the first insulating layer 12.

[0083] (5) Etching process Next, in the etching process, the substrate M is etched to form a metal support layer 11 (see Figure 2A).

[0084] This results in the manufacture of the wiring circuit board 1 shown in Figure 1.

[0085] 4. Effects According to the wiring circuit board 1, as shown in Figures 1 and 2A, in at least the wiring section 3A, the wiring 133A has a first conductor layer 1331 and a second conductor layer 1332.

[0086] The second conductor layer 1332 covers the first conductor layer 1331 and is in contact with the first insulating layer 12. Therefore, compared to the case where the wiring 133A is formed from the first conductor layer 1331 alone, the second conductor layer 1332 can increase both the width W11 and the thickness T11 of the wiring 133A.

[0087] As a result, the cross-sectional area of ​​wiring 133A can be increased, and the electrical resistance of wiring 133A can be reduced.

[0088] Here, as shown in Figure 4A, the second conductor layer 1332 can be formed by plating growth in both the width direction and the thickness direction using the first conductor layer 1331 as a seed. In this case, plating growth in the width direction may be inhibited by the plating resist R2, and recesses 1330 (parts where plating growth is inhibited) may be formed on the side surfaces S2 and S3 of the wiring 133A.

[0089] If excessively deep recesses 1330 are formed on the sides S2 and S3 of the wiring 133A, the electrical resistance of the wiring 133A may increase due to the recesses 1330, potentially preventing a sufficient reduction in the electrical resistance of the wiring 133A.

[0090] In this regard, the ratio of the thickness T11 of the wiring 133A to the thickness T21 of the first conductor layer 1331 (T11 / T21) is 2.0 or greater.

[0091] Therefore, the depth D1 of the recess 1330 (see Figure 2A) can be reduced, and the electrical resistance of the wiring 133A can be reduced more reliably.

[0092] 5. Variations A modified example will now be described. In the modified example, the same reference numerals are used for components similar to those in the above-described embodiment, and their descriptions are omitted.

[0093] As shown in Figure 5, the wiring 133A and 133B of the support portion 2 may be formed from only the first conductor layer 1331.

[0094] Even with modified forms, the same effects and benefits as those of the embodiments described above can be obtained. [Examples]

[0095] The present invention will be further described below with reference to examples and comparative examples. However, the present invention is not limited in any way to the examples and comparative examples. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical properties, and parameters used in the following description may be replaced with the upper limits (numerical values ​​defined as "less than or equal to" or "less than") or lower limits (numerical values ​​defined as "greater than or equal to" or "greater than or equal to") of the corresponding blending ratios (content ratios), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0096] 1. Manufacturing of wiring circuit boards Using the wiring circuit board manufacturing method described above, a wiring circuit board having wiring with the dimensions (width and thickness) listed in Table 1 was manufactured. The first conductor layer and the second conductor layer were formed by electrolytic copper plating on a seed layer made of chromium.

[0097] 2. Evaluation Using a microtome (Leica Biosystems), the wiring circuit board after the formation of the second conductor layer was cut in the thickness direction (perpendicular direction). Next, the cut cross-section was photographed using a CCD (Olympus). The obtained images were observed at 100x magnification, and the depth of the recesses on the sides of the wiring and the presence or absence of gaps between the first and second conductor layers were measured. The results are shown in Table 1.

[0098] [Table 1] From a comparison between Example 1 and Comparative Example 2, and between Example 3 and Comparative Example 1, it can be seen that if the ratio of the wiring thickness T11 to the thickness T21 of the first conductor layer (T11 / T21) is 2.0 or greater, the depth of the recess can be significantly reduced.

[0099] Furthermore, from Examples 1 to 3, it can be seen that as the size of the first conductor layer (width W21 and thickness T21) decreases and the distances D11 and D12 between each of the two sides of the wiring and the first conductor layer increase (i.e., the distance between the first conductor layer and the plating resist in the second conductor layer formation process), the depth of the recess can be reduced.

[0100] Furthermore, a comparison between Example 3 and Example 4 shows that the depth of the recess can also be reduced by decreasing the thickness T21 of the first conductor layer. [Explanation of Symbols]

[0101] 1 Wiring circuit board 2 Support part 3A wiring section 11 Metal support layer 12. First insulating layer (an example of an insulating layer) 133A Wiring 1330 recess 1331 First Conductor Layer 1332 Second Conductor Layer S2 One side of the wiring in the width direction S3 The other side of the wiring in the width direction D11 Distance between one side of the wiring in the width direction and the first conductor layer D12 Distance between the other side of the wiring in the width direction and the first conductor layer T11 Wiring Thickness T21 Thickness of the first conductor layer W11 Wiring width W21 Width of the first conductor layer

Claims

1. It comprises a wiring section and a support section that supports one end of the wiring section, The wiring section comprises a metal support layer, an insulating layer disposed on the metal support layer, and wiring disposed on the insulating layer. At least in the wiring section, the wiring is A first conductor layer disposed on the insulating layer, A second conductor layer that covers the first conductor layer and is in contact with the insulating layer It has, A wiring circuit board in which the ratio of the thickness of the wiring to the thickness of the first conductor layer is 2.0 or more.

2. The wiring circuit board according to claim 1, wherein the ratio of the thickness of the first conductor layer to the width of the first conductor layer is 0.3 or more and 1.1 or less.

3. The wiring circuit board according to claim 1, wherein the width of the wiring is greater than the width of the first conductor layer.

4. The wiring circuit board according to claim 1, wherein in the width direction of the wiring, the distance between each of the two sides of the wiring and the first conductor layer is 10.00 μm or more.

5. The wiring has a central portion and an end portion in the width direction of the wiring, The wiring circuit board according to claim 1, wherein the central portion protrudes in the thickness direction toward the opposite side of the metal support layer from the insulating layer compared to the end portion.

6. The wiring has recesses on each of its two sides in the width direction, The wiring circuit board according to claim 1, wherein the depth of the recess is 0.7 μm or less.

7. The support portion has wiring that is continuous with the wiring of the wiring portion. The wiring of the support portion comprises the first conductor layer and the second conductor layer, as described in claim 1.

8. The aforementioned wiring circuit board has a plurality of wiring sections arranged at intervals from each other, The wiring circuit board according to claim 1, wherein the support portion supports one end of each of the plurality of wiring portions.

Images