Wiring circuit board

Abstract

The present invention provides a wiring circuit board and a method thereof that can suppress the variation of electrical characteristics of the first wiring section more effectively than the variation of electrical characteristics of the second wiring section. The wiring circuit board 1 of the present invention has a porous insulating layer 2 and a first conductor layer 31 sequentially provided on the side facing the thickness direction. The first conductor layer 31 has a first signal line 34 and a first ground line 35. The first ground line 35 is thicker than the first signal line 34.

Description

Technical Field

[0001] This invention relates to a wiring circuit board and its manufacturing method. Prior Technology

[0002] A wiring circuit board is known, which comprises a porous insulating resin film and a conductive layer (see, for example, Patent Document 1 below). In the wiring circuit board described in Patent Document 1, the conductive layer has a plurality of wirings. In Patent Document 1, the plurality of wiring portions have the same thickness. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-123851 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] Depending on the application and purpose, sometimes pressure needs to be applied to the circuit board substrate in the thickness direction. In this case, the thickness of the multiple portions of the porous insulating resin film that overlap with the multiple wiring portions changes uniformly due to the pressure. As a result, there may be an undesirable situation where the electrical characteristics of the multiple wirings change uniformly.

[0006] The present invention provides a wiring circuit board and a method thereof that can suppress the variation of electrical characteristics of the first wiring section more effectively than the variation of electrical characteristics of the second wiring section. [Technical means to solve the problem]

[0007] The present invention (1) includes a wiring circuit board having a porous insulating layer and a conductor layer sequentially disposed on one side facing the thickness direction, wherein the conductor layer has a first wiring portion and a second wiring portion that is thicker than the first wiring portion.

[0008] In this wiring circuit board, the second wiring portion is thicker than the first wiring portion. In other words, the first wiring portion is thinner than the second wiring portion.

[0009] Therefore, when pressure is applied to the wiring circuit board in the thickness direction, the porous insulating layer overlapping the first wiring portion in the thickness direction experiences less pressure compared to the porous insulating layer overlapping the second wiring portion in the thickness direction. Consequently, the thickness variation of the porous insulating layer overlapping the first wiring portion in the thickness direction is more effectively suppressed compared to the thickness variation of the porous insulating layer overlapping the second wiring portion in the thickness direction.

[0010] As a result, the changes in the electrical characteristics of the first wiring section are suppressed more effectively than the changes in the electrical characteristics of the second wiring section.

[0011] The present invention (2) includes a wiring circuit board as described in (1), wherein two of the second wiring portions are arranged at intervals in a direction orthogonal to the thickness direction, and the first wiring portion is arranged between the two second wiring portions.

[0012] In this wiring circuit board, when pressure is applied, the porous insulating layer overlapping the two second wiring portions in the thickness direction can withstand a large pressure with good balance. Therefore, the porous insulating layer overlapping the first wiring portion disposed between the two second wiring portions is subjected to a smaller pressure. Therefore, compared to the thickness variation of the porous insulating layer overlapping the second wiring portions in the thickness direction, the thickness variation of the porous insulating layer overlapping the first wiring portion in the thickness direction is better suppressed.

[0013] The present invention (3) includes a wiring circuit board as described in (1) or (2), which further includes a ground layer disposed on the other side of the porous insulating layer in the thickness direction. The ground layer has a third wiring portion that overlaps with the first wiring portion when projected in the thickness direction, and a fourth wiring portion that overlaps with the second wiring portion, and the fourth wiring portion is thicker than the third wiring portion.

[0014] In this wiring circuit board, since the ground layer has a third wiring portion that overlaps with the first wiring portion and a fourth wiring portion that overlaps with the second wiring portion and is thicker than the third wiring portion, when pressure is applied to the wiring circuit board in the thickness direction, the porous insulating layer that overlaps with the first wiring portion in the thickness direction experiences less pressure than the porous insulating layer that overlaps with the second wiring portion in the thickness direction. Therefore, the thickness variation of the porous insulating layer that overlaps with the first wiring portion in the thickness direction is more effectively suppressed compared to the thickness variation of the porous insulating layer that overlaps with the second wiring portion in the thickness direction.

[0015] The present invention (4) includes a wiring circuit board as described in (3), wherein the porous insulating layer has a through hole penetrating the porous insulating layer in the thickness direction, and the wiring circuit board further has a conductor connection portion filling the through hole and contacting the conductor layer and the ground layer.

[0016] The present invention (5) includes a wiring circuit board as described in any one of (1) to (4), which further includes an adhesive layer and a covering insulating layer, wherein the covering insulating layer is covered by the conductor layer and the porous insulating layer from the thickness direction side through the adhesive layer.

[0017] The present invention (6) includes a method for manufacturing a wiring circuit board, comprising: a first step of which a conductor layer having a first wiring portion and a second wiring portion thicker than the first wiring portion is disposed on one side of a porous insulating layer in the thickness direction; and a second step of which a covering insulating layer is pressurized onto the conductor layer and the porous insulating layer through an adhesive layer.

[0018] In this manufacturing method, in step 2, a covering insulating layer is pressurized onto the conductor layer and the porous insulating layer over an adhesive layer. This allows for greater suppression of thickness variation in the porous insulating layer overlapping the first wiring portion in the thickness direction, even when a larger pressure is applied to the porous insulating layer, compared to the thickness variation of the porous insulating layer overlapping the second wiring portion in the thickness direction. Consequently, variations in the electrical characteristics of the first wiring portion are suppressed more effectively than variations in the electrical characteristics of the second wiring portion. [Effects of the Invention]

[0019] According to the wiring circuit board and manufacturing method of the present invention, the variation of the electrical characteristics of the first wiring section is more effectively suppressed compared with the variation of the electrical characteristics of the second wiring section. Simple Explanation of the Diagram

[0020] Figure 1 shows a cross-sectional view of one embodiment of the present invention. Figures 2A to 2D illustrate the manufacturing steps of the wiring circuit board shown in Figure 1. Figure 2A shows the steps for preparing the first porous bulk layer. Figure 2B shows the steps for forming the first via. Figure 2C shows the steps for forming the first plating layer. Figure 2D shows the steps for patterning the second conductor layer. Figures 3A to 3C illustrate the manufacturing steps of the wiring circuit board following Figure 2D. Figure 3A shows the step of bonding the second porous bulk material to the second conductor layer. Figure 3B shows the steps of forming the second and third vias. Figure 3C shows the steps of forming the second plating layer. Figures 4A and 4B are manufacturing steps of the wiring circuit board following Figure 3C. Figure 4A shows the steps of patterning the first plating layer and the first base layer. Figure 4B shows the steps of bonding the first cover layer and the second cover layer. Figure 5 is a cross-sectional view of a variation of the wiring circuit board. Figure 6 is a cross-sectional view of a variation of the wiring circuit board. Figure 7 is a cross-sectional view of a variation of the wiring circuit board. Implementation

[0021] 1. One embodiment of the wiring circuit board Referring to FIG1, one embodiment of the wiring circuit board of the present invention will be described.

[0022] The wiring circuit board 1 has a thickness. The wiring circuit board 1 extends in the surface direction. The surface direction is orthogonal to the thickness direction. The wiring circuit board 1 has a generally flat shape.

[0023] The wiring circuit board 1 has a porous insulating layer 2 and a conductor layer 3 sequentially arranged in the thickness direction. The porous insulating layer 2 has a first porous insulating layer 21 and a second porous insulating layer 22 sequentially arranged in the thickness direction. The conductor layer 3 has a first conductor layer 31, a second conductor layer 32 and a third conductor layer 33 sequentially arranged in the thickness direction. Specifically, the wiring circuit board 1 has a third conductor layer 33, a second porous insulating layer 22, a second conductor layer 32, a first porous insulating layer 21 and a first conductor layer 31 sequentially arranged on the side facing the thickness direction. Furthermore, the wiring circuit board 1 has a conductor connection portion 4, a covering insulating layer 5 and an adhesive layer 6.

[0024] 2. Porous insulating layer 2 The porous insulating layer 2 has a first porous insulating layer 21 and a second porous insulating layer 22 sequentially on the other side in the thickness direction.

[0025] 2.1 First porous insulating layer 21 The first porous insulating layer 21 has a thickness. The first porous insulating layer 21 extends in the planar direction. The first porous insulating layer 21 has a generally flat plate shape. The first porous insulating layer 21 has a first through hole 23 and two second through holes 24.

[0026] The first through hole 23 is disposed in the middle portion of the first porous insulating layer 21 in the first direction. The first direction includes the planar direction.

[0027] A second through hole 24 is disposed on one side of the first through hole 23, spaced apart in the first direction. Another second through hole 24 is disposed on the other side of the first through hole 23, also spaced apart in the first direction. Another second through hole 24 is disposed on the opposite side of the first through hole 24 in the first direction, opposite to the first through hole 23. Thus, the first through hole 24, the first through hole 23, and the other second through hole 24 are arranged sequentially in the first direction. That is, the first through hole 23 is disposed between the two second through holes 24.

[0028] The first through hole 23 and the two second through holes 24 penetrate the first porous insulating layer 21 in the thickness direction. The inner circumferential surface of each of the first through hole 23 and the two second through holes 24 in the first porous insulating layer 21 is along the thickness direction. The aforementioned inner circumferential surface may have a conical shape in which the cross-sectional area gradually increases towards the thickness direction.

[0029] 2.2 Second porous insulating layer 22 The second porous insulating layer 22 is disposed on the other side of the first porous insulating layer 21 in the thickness direction. The second porous insulating layer 22 is spaced apart from the first porous insulating layer 21 in the thickness direction. Furthermore, the second porous insulating layer 22 is attached to the first porous insulating layer 21 via the second bonding layer 62 described below.

[0030] The second porous insulating layer 22 has a thickness. The second porous insulating layer 22 extends in the planar direction. The second porous insulating layer 22 has a generally flat plate shape. The second porous insulating layer 22 has two third through holes 25.

[0031] When projected along the thickness direction, the two third through holes 25 overlap with each of the two second through holes 24. The two third through holes 25 are arranged at intervals from each other in the first direction.

[0032] Two third through holes 25 penetrate the second porous insulating layer 22 in the thickness direction. The inner circumferential surface of each of the two third through holes 25 in the second porous insulating layer 22 is along the thickness direction. The aforementioned inner circumferential surface may have a conical shape in which the cross-sectional area gradually increases towards the other side of the thickness direction.

[0033] 2.3 Material of Porous Insulation Layer 2 Resins can be used as materials for the porous insulating layer 2. The resin is not limited. Examples of resins include: polycarbonate resin, polyimide resin, fluorinated polyimide resin, epoxy resin, phenolic resin, urea resin, melamine resin, diallyl phthalate resin, silicone resin, thermosetting polyurethane resin, fluoropolymer, and liquid crystal polymer. Polyimide resin and liquid crystal polymer are preferred examples.

[0034] 2.4 Physical properties of porous insulating layer 2 The porous insulating layer 2 is porous. The porous insulating layer 2 has independent bubbles and / or continuous bubbles.

[0035] The porosity of the porous insulating layer 2 is, for example, 50% or more, preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. Furthermore, the porosity of the porous insulating layer 2 is, for example, less than 100%, and even less than 99%. Regarding the porosity of the porous insulating layer 2, when the material of the porous insulating layer 2 is polyimide resin, it can be calculated based on the following formula.

[0036] The dielectric constant of porous insulating layer 2 = dielectric constant of air × porosity + dielectric constant of polyimide × (1 - porosity) Here, since the dielectric constant of air is 1 and the dielectric constant of polyimide resin is 3.5, therefore... The dielectric constant of porous insulating layer 2 = porosity + 3.5(1 - porosity) Porosity (%) = [(3.5 - dielectric constant of porous insulating layer 2) / 2.5] × 100

[0037] The dielectric constant of the porous insulating layer 2 at a frequency of 60 GHz is, for example, 2.5 or less, preferably 1.9 or less, more preferably 1.6 or less, and, for example, greater than 1.0. The dielectric constant of the porous insulating layer 2 is actually measured using a resonator method at a frequency of 60 GHz.

[0038] The dielectric loss factor of the porous insulating layer 2 at a frequency of 60 GHz is, for example, less than 0.006, or, for example, greater than 0. The dielectric loss factor of the porous insulating layer 2 is actually measured using the resonator method at a frequency of 60 GHz.

[0039] 3. Conductor layer 3 The conductor layer 3 extends in the second direction. The second direction intersects the thickness direction and the first direction. Specifically, the second direction is orthogonal to the thickness direction and the first direction.

[0040] The conductor layer 3 has a first conductor layer 31, a second conductor layer 32 and a third conductor layer 33 in sequence on the other side of the thickness direction.

[0041] 3.1 First Conductor Layer 31 The first conductor layer 31 is disposed on one side of the first porous insulating layer 21 in the thickness direction. Specifically, the first conductor layer 31 is disposed on one side of the first porous insulating layer 21 in the thickness direction. The first conductor layer 31 has a first signal line 34 as an example of a first wiring section, and two first ground lines 35 as examples of two second wiring sections.

[0042] 3.1.1 Signal Line 1 34 The first signal line 34 transmits a signal in the second direction. A differential signal can be exemplified as a signal. The signal may include, for example, a small current less than 1 A, and further less than 0.1 A. The first signal line 34 is disposed in the middle portion of the first conductor layer 31 in the first direction. The first signal line 34 is disposed on one side of the first through-hole 23 in the thickness direction. The first signal line 34 blocks one end of the first through-hole 23 in the thickness direction. The first signal line 34 contacts one side of the first through-hole 23 in the thickness direction surrounding the first porous insulating layer 21. The first signal line 34 includes a signal terminal 341. The signal terminal 341 is disposed at the end of the first signal line 34 in the second direction. An electrode of an external substrate (not shown) is connected to the signal terminal 341.

[0043] The first signal line 34 is thinner than the first ground line 35, as described below. Specifically, the thickness T1 of the first signal line 34 is, for example, 50 μm or less, preferably 35 μm or less, more preferably 18 μm or less, and, for example, 4 μm or more. Furthermore, the thickness T1 of the first signal line 34 is the thickness direction length between one side of the thickness direction of the first porous insulating layer 21 and one side of the thickness direction of the first signal line 34.

[0044] 3.1.2 Two first grounding wires, 35 The two first grounding wires 35 will each ground a small current that affects the first signal line 34. This small current includes, for example, currents less than 1 A, and even less than 0.1 A. The two first grounding wires 35 are respectively disposed on one side of the thickness direction of each of the two second through holes 24. The two first grounding wires 35 respectively block one end of the thickness direction of each of the two second through holes 24. The two first grounding wires 35 are respectively in contact with one side of the thickness direction surrounding the two second through holes 24 in the first porous insulating layer 21.

[0045] Two first ground wires 35 are arranged spaced apart from each other in a first direction. A first ground wire 35 is arranged spaced apart in a first direction on one side of the first signal line 34. Another first ground wire 35 is disposed on the other side of the first signal wire 34, spaced apart in the first direction. Another first ground wire 35 is disposed on the opposite side of the first ground wire 35 in the first direction relative to the first signal wire 34. Thus, the first ground wire 35, the first signal wire 34, and the other first ground wire 35 are arranged sequentially with intervals in the first direction. That is, the first signal wire 34 is disposed between the two first ground wires 35.

[0046] At least one of the two first grounding wires 35 includes a grounding terminal 351. The grounding terminal 351 is disposed at the end of the first grounding wire 35 in a second direction. A grounding member (not shown) is connected to the grounding terminal 351.

[0047] The two first ground wires 35 are thicker than the first signal wire 34.

[0048] On the other hand, if the two first ground wires 35 have the same thickness as the first signal wire 34, the applied pressure described below will cause a significant change in the thickness of the porous insulating layer 2 that overlaps with the first signal wire 34 and the first ground wire 35 in the thickness direction, and the electrical characteristics of the first signal wire 34 will change significantly. Specifically, this will result in a mismatch in the characteristic impedance of the first signal wire 34.

[0049] The thickness T2 of the two first grounding wires 35 is, for example, 6 μm or more, preferably 20 μm or more, more preferably 40 μm or more, and, for example, 52 μm or less. Furthermore, the thickness T2 of the first grounding wire 35 is the thickness length between one side of the thickness direction of the first porous insulating layer 21 and one side of the thickness direction of the first grounding wire 35.

[0050] The ratio (T2 / T1) of the thickness T2 of the first grounding wire 35 to the thickness T1 of the first signal wire 34 is greater than 1, preferably 1.2 or more, more preferably 1.4 or more, and even more preferably 1.6 or more. There is no upper limit to the ratio (T2 / T1) of the thickness T2 of the first grounding wire 35 to the thickness T1 of the first signal wire 34. For example, the upper limit of the ratio (T2 / T1) is 13.

[0051] 3.2 Second conductor layer 32 The second conductor layer 32 is disposed on the opposite side of the first porous insulating layer 21 in the thickness direction. The second conductor layer 32 is disposed on the opposite side of the first porous insulating layer 21 in the thickness direction. The second conductor layer 32 is disposed between the first porous insulating layer 21 and the second porous insulating layer 22 in the thickness direction. The second conductor layer 32 is electrically connected to the first conductor layer 31. The second conductor layer 32 includes a second signal line 36 and two second ground lines 37.

[0052] 3.2.1 Signal line 2, number 36 The second signal line 36 transmits the aforementioned signal together with the first signal line 34 in the second direction. The second signal line 36 overlaps with the first signal line 34 when projected along the thickness direction. The second signal line 36 is electrically connected to the first signal line 34 in the thickness direction.

[0053] 3.2.2 Two second grounding wires 37 The two second grounding wires 37, together with the two first grounding wires 35, will generate a weak current grounding that affects the first signal line 34 and the second signal line 36. The two second grounding wires 37 are respectively spaced apart and arranged on one side of the second signal line 36 in the first direction and the other side. When projected along the thickness direction, the second grounding wires 37 overlap with the first grounding wires 35.

[0054] The two second ground wires 37 each have the same thickness as the second signal wire 36.

[0055] 3.3 Third Conductor Layer 33 The third conductor layer 33 is an example of a ground layer. That is, the third conductor layer 33, together with the first ground wire 35 and the second ground wire 37, will ground the weak current that affects the first signal line 34 and the second signal line 36.

[0056] The third conductor layer 33 is disposed on the opposite side of the second porous insulating layer 22 in the thickness direction. Specifically, the third conductor layer 33 is disposed on the opposite side of the second porous insulating layer 22 in the thickness direction. The third conductor layer 33 is disposed on the opposite side of the second conductor layer 32 in the thickness direction relative to the second porous insulating layer 22. The third conductor layer 33 has a third grounding portion 38 as an example of a third wiring portion and a fourth grounding portion 39 as an example of a fourth wiring portion.

[0057] 3.3.1 Third grounding part 38 The third grounding portion 38 is disposed on the other side of the second porous insulating layer 22 in the thickness direction between the two third through holes 25. The third grounding portion 38 extends in the first direction. When projected along the thickness direction, the third grounding portion 38 overlaps with the first signal line 34. When projected along the thickness direction, the third grounding portion 38 includes the first signal line 34. Specifically, the third grounding portion 38 includes an overlapping portion 381 and a non-overlapping portion 382. The overlapping portion 381 overlaps with the first signal line 34. The non-overlapping portion 382 does not overlap with the first signal line 34. In this embodiment, the overlapping portion 381 is the middle portion of the third grounding portion 38 in the first direction. The non-overlapping portion 382 extends outward from one end and the other end of the overlapping portion 381 in the first direction. The third grounding portion 38 has a flat plate shape.

[0058] The third grounding portion 38 is thinner than the fourth grounding portion 39, as described below. Specifically, the thickness T3 of the third grounding portion 38 is, for example, 50 μm or less, preferably 35 μm or less, more preferably 18 μm or less, and, for example, 4 μm or more. Furthermore, the thickness T3 of the third grounding portion 38 is the length in the thickness direction between the other side of the second porous insulating layer 22 in the thickness direction and the other side of the third grounding portion 38 in the thickness direction.

[0059] 3.3.2 Fourth grounding part 39 Two fourth grounding portions 39 are respectively disposed on the other side of the thickness direction of each of the two third through holes 25. The two fourth grounding portions 39 respectively block the other end of the thickness direction of each of the two third through holes 25. The two fourth grounding portions 39 respectively contact the other side of the thickness direction surrounding the two third through holes 25 in the second porous insulating layer 22.

[0060] Two fourth grounding portions 39 are arranged spaced apart from each other in the first direction. Each of the two fourth grounding portions 39 has a flat plate shape. When projected along the thickness direction, the fourth grounding portion 39 overlaps with the first grounding wire 35. A portion of one fourth grounding portion 39 in the thickness direction is connected to one end (non-overlapping portion 382) of the third grounding portion 38 in the first direction. A portion of the other fourth grounding portion 39 in the thickness direction is connected to the other end (non-overlapping portion 382) of the third grounding portion 38 in the first direction. Thus, the two fourth grounding portions 39 are electrically connected to each other via the third grounding portion 38.

[0061] The two fourth ground portions 39 are each thicker than the third ground portion 38. If the two fourth ground portions 39 are each thicker than the third ground portion 38, the thickness of the porous insulating layer 2 that overlaps with the third ground portion 38 and the fourth ground portion 39 in the thickness direction due to the pressure applied as described below can be suppressed, thereby suppressing the large changes in the electrical characteristics of the first signal line 34 and the second signal line 36.

[0062] The thickness T4 of the two fourth grounding portions 39 is, for example, 6 μm or more, preferably 20 μm or more, more preferably 40 μm or more, and, for example, 52 μm or less. The thickness T4 of the fourth grounding portion 39 is the thickness direction length between the other side of the thickness direction of the second porous insulating layer 22 and the other side of the thickness direction of the fourth grounding portion 39.

[0063] The ratio (T4 / T3) of the thickness T4 of the fourth grounding portion 39 to the thickness T3 of the third grounding portion 38 is greater than 1, preferably 1.2 or more, more preferably 1.4 or more, and even more preferably 1.6 or more. There is no upper limit to the ratio (T4 / T3) of the thickness T4 of the fourth grounding portion 39 to the thickness T3 of the third grounding portion 38. For example, the upper limit of the ratio (T4 / T3) is 13.

[0064] 3.4 Material of Conductor Layer 3 The material of conductor layer 3 is not limited. Examples of materials for conductor layer 3 include copper, iron, silver, gold, aluminum, nickel, and alloys thereof (stainless steel and bronze). Copper is a preferred material for conductor layer 3.

[0065] 4. Conductor connection part 4 The conductor connection portion 4 is disposed between the first conductor layer 31 and the second conductor layer 32, and between the second conductor layer 32 and the third conductor layer 33, in the thickness direction. The conductor connection portion 4 is disposed in the first through hole 23, the second through hole 24, and the third through hole 25. The conductor connection portion 4 has a first conductor connection portion 41, two second conductor connection portions 42, and two third conductor connection portions 43.

[0066] 4.1 First conductor connection part 41 A portion (the main part) of the first conductor connection 41 fills the first through hole 23, and the remaining portion (the other end in the thickness direction) of the first conductor connection 41 protrudes from the first through hole 23 toward the other side in the thickness direction. One end of the first conductor connection 41 in the thickness direction contacts (continuously) the first signal line 34. The other end of the first conductor connection 41 in the thickness direction contacts the second signal line 36. Thus, the first signal line 34 and the second signal line 36 are electrically connected via the first conductor connection 41. Therefore, the first signal line 34, the second signal line 36, and the first conductor connection 41 form a generally I-shaped signal path when viewed in cross-section. The signal path extends in both the thickness direction and the second direction.

[0067] 4.2 Second conductor connection part 42 A portion (the main part) of the second conductor connection 42 fills the second through hole 24, and the remaining portion (the other end in the thickness direction) of the second conductor connection 42 protrudes from the second through hole 24 toward the other side in the thickness direction. One end of the second conductor connection 42 in the thickness direction contacts the first grounding wire 35 (continuously). The other end of the second conductor connection 42 in the thickness direction contacts the second grounding wire 37. Thus, the first grounding wire 35 and the second grounding wire 37 are electrically connected via the second conductor connection 42.

[0068] 4.3 Third conductor connection part 43 A portion (main part) of the third conductor connection 43 fills the third through hole 25, and the remaining portion (one end in the thickness direction) of the third conductor connection 43 protrudes from the third through hole 25 towards the thickness direction. The other end of the third conductor connection 43 in the thickness direction contacts the fourth grounding portion 39 (continuously). One end of the third conductor connection 43 in the thickness direction contacts the second grounding wire 37. Thus, the second grounding wire 37 and the third conductor layer 33 are electrically connected via the third conductor connection 43.

[0069] As described above, the first grounding wire 35, the second grounding wire 37, the third conductor layer 33, the second conductor connection portion 42, and the third conductor connection portion 43 form a roughly U-shaped grounding path when viewed in cross-section. The grounding path is open towards the thickness direction when viewed in cross-section.

[0070] 4.4 Material of conductor connection part 4 The material of the conductor connection part 4 is the same as the material of the conductor layer 3 mentioned above.

[0071] 5. Cover with insulation layer 5 The covering insulation layer 5 is disposed on one side and the other side in the thickness direction of the conductor layer 3. The covering insulation layer 5 has a first covering insulation layer 51 and a second covering insulation layer 52.

[0072] 5.1 First Cover Insulation Layer 51 The first covering insulating layer 51 is disposed on one side of the first conductor layer 31 in the thickness direction. The first covering insulating layer 51 forms one side of the wiring circuit board 1 in the thickness direction. The first covering insulating layer 51 exposes the signal terminal 341 and the ground terminal 351. The first covering insulating layer 51 covers the first conductor layer 31 except for the signal terminal 341 and the ground terminal 351.

[0073] 5.2 Second Cover Insulation Layer 52 The second covering insulating layer 52 is disposed on the other side of the third conductor layer 33 in the thickness direction. The second covering insulating layer 52 forms the other side of the wiring circuit board 1 in the thickness direction. The second covering insulating layer 52 covers the third conductor layer 33.

[0074] 5.3 Material of the covering insulation layer 5 The resin mentioned above can be used as a material for covering the insulating layer 5.

[0075] 6. Next, layer 6 Adhesive layer 6 is disposed between the above layers. The material (or raw material) of adhesive layer 6 is not limited. Adhesive layer 6 has a first adhesive layer 61, a second adhesive layer 62 and a third adhesive layer 63 in sequence on the other side in the thickness direction.

[0076] 6.1 The first layer followed by 61 The first bonding layer 61 is disposed on one side of the first conductor layer 31 and the first porous insulating layer 21 along their thickness direction, and on the other side of the first covering insulating layer 51 along its thickness direction. The first bonding layer 61 bonds the first conductor layer 31 and the first porous insulating layer 21 to the first covering insulating layer 51. The first bonding layer 61 contacts one side and one side of the first conductor layer 31 along its thickness direction, and one side of the first porous insulating layer 21 surrounding the first conductor layer 31 along its thickness direction. The first bonding layer 61 contacts the other side of the first covering insulating layer 51 along its thickness direction.

[0077] 6.2 The second layer 62 The second bonding layer 62 is disposed on the other side of the first porous insulating layer 21 in the thickness direction and on one side of the second porous insulating layer 22 in the thickness direction. That is, the second bonding layer 62 is disposed between the first porous insulating layer 21 and the second porous insulating layer 22. The second bonding layer 62 has a second conductor layer 32 embedded in its thickness direction. Specifically, the second bonding layer 62 contacts both sides and the side of the second conductor layer 32 in the thickness direction. Furthermore, the second bonding layer 62 contacts the side of the remaining portion of the conductor connection portion 4. Specifically, the second bonding layer 62 contacts the peripheral side of the other end of the first conductor connection portion 41 in the thickness direction, the peripheral side of the other end of the second conductor connection portion 42 in the thickness direction, and the peripheral side of one end of the third conductor connection portion 43 in the thickness direction.

[0078] 6.3 The third layer 63 The third bonding layer 63 is disposed on the other side of the third conductor layer 33 and the second porous insulating layer 22 in the thickness direction, and on one side of the second covering insulating layer 52 in the thickness direction. Furthermore, in Figure 1, the arrangement of the third bonding layer 63 on the other side of the second porous insulating layer 22 in the thickness direction is not shown. The third bonding layer 63 bonds the third conductor layer 33 and the second porous insulating layer 22 to the second covering insulating layer 52. The third bonding layer 63 contacts the other side and the side surface of the third conductor layer 33 in the thickness direction, as well as the other side of the second porous insulating layer 22 in the thickness direction surrounding the third conductor layer 33.

[0079] 7. Fourth bonding layer 64 and reinforcing layer 7 Furthermore, the wiring circuit board 1 may further include a fourth bonding layer 64 represented by imaginary lines and a reinforcing layer 7.

[0080] The fourth bonding layer 64 is disposed on the other side of the second covering insulating layer 52 in the thickness direction. The fourth bonding layer 64 bonds the second covering insulating layer 52 to the reinforcing layer 7 described below.

[0081] The reinforcing layer 7 reinforces the first signal line 34 and the third ground portion 38. The reinforcing layer 7 is disposed on the other side of the second covering insulating layer 52 in the thickness direction. Specifically, the reinforcing layer 7 is attached to the other side of the second covering insulating layer 52 in the thickness direction via the fourth bonding layer 64. The reinforcing layer 7 overlaps with the first signal line 34 and the third ground portion 38 when projected along the thickness direction. The reinforcing layer 7 has a flat plate shape. The material of the reinforcing layer 7 is not limited. Examples of materials for the reinforcing layer 7 include metals and rigid resins. A metal is preferred as the material for the reinforcing layer 7; examples include stainless steel, copper, iron, and aluminum. The thickness of the reinforcing layer 7 is not limited.

[0082] 8. Manufacturing method of wiring circuit board 1 The manufacturing method of the wiring circuit board 1 will be described below with reference to Figures 1 to 4B.

[0083] 8.1 Preparation of the first porous mass layer 81 As shown in Figure 2A, in this method, the first porous mass-produced layer 81 is first prepared.

[0084] The first porous laminate 81 has a second conductor layer 32, a second adhesive layer 62A on one side, a first porous insulating layer 21 and a first substrate layer 311 in sequence on one side facing the thickness direction.

[0085] The second conductor layer 32 in the first porous multilayer 81 is disposed on the other side of the thickness direction of the first porous insulating layer 21. The second conductor layer 32 in the first porous multilayer 81 has not been patterned and is not the second conductor layer 32 of the wiring circuit board 1 shown in FIG1.

[0086] The second bonding layer 62A is disposed on one side of the second conductor layer 32 in the thickness direction and on the other side of the first porous insulating layer 21 in the thickness direction.

[0087] The first substrate layer 311 is disposed on one side of the first porous insulating layer 21 in the thickness direction. The first substrate layer 311 is included in the first conductor layer 31 of the wiring circuit board 1 in FIG1.

[0088] The method for preparing the first porous mass layer 81 is described, for example, in Japanese Patent Application Publication No. 2019-123851.

[0089] 8.2 Formation of the first through hole 91 As shown in Figure 2B, a first through-hole 91 is then formed in the first base layer 311, the first porous insulating layer 21, and the second adhesive layer 62A on one side. Furthermore, the first through-hole 91 in the first porous insulating layer 21 is the aforementioned first through-hole 23.

[0090] Methods for forming the first through hole 91 include, for example, perforation. Examples of perforation methods include laser machining, drilling, and blasting. Laser machining is preferred.

[0091] 8.3 Formation of the first coating layer 312 As shown in Figure 2C, a first plating layer 312 is then formed on one of the inner peripheral surfaces of the first through hole 91 and the thickness direction of the first base layer 311. The first plating layer 312 formed on the inner peripheral surface of the first through hole 91 is the aforementioned first conductor connection portion 41.

[0092] 8.4 Patterning of the second conductor layer 32 As shown in Figure 2D, the second conductor layer 32 is patterned to form the second signal line 36 and two second ground lines 37. For example, wet etching and dry etching can be used to pattern the second conductor layer 32, with wet etching being a preferred method.

[0093] 8.5 Adhesion of the second porous mass layer 82 to the second conductor layer 32 As shown in the lower side view of Figure 2D and Figure 3A, the second porous mass layer 82 is attached to the second conductor layer 32.

[0094] As shown in the lower view of Figure 2D, a second porous mass stack 82 is first prepared. The second porous mass stack 82 has a second bonding layer 62B, a second porous insulating layer 22 and a second base layer 331 on the other side in the thickness direction.

[0095] The second bonding layer 62B on the other side is disposed on one side of the second porous insulating layer 22 in the thickness direction.

[0096] The second substrate layer 331 is disposed on the other side of the second porous insulating layer 22 in the thickness direction. The second substrate layer 331 is included in the aforementioned third conductor layer 33.

[0097] The method for preparing the second porous mass matrix 82 is described, for example, in Japanese Patent Application Publication No. 2019-123851.

[0098] Next, as shown by the arrow in Figure 2D and Figure 3A, the second bonding layer 62B on the other side of the second porous bulk material 82 is attached to the second conductor layer 32. At this time, a press (not shown) capable of applying pressure in the thickness direction is used. The pressure applied is not limited. The pressure applied is, for example, 0.5 MPa or more, preferably 3 MPa or more, and also, for example, 10 MPa or less. The pressing time is, for example, 1 minute or more, preferably 10 minutes or more, and also, for example, 120 minutes or less. Pressurization can also be hot pressing. The pressing temperature is, for example, 80°C or more, preferably 120°C or more, and also, for example, 300°C or less.

[0099] During the bonding of the second bonding layer 62B on the other side, the second bonding layer 62A on one side and the second bonding layer 62B on the other side deform and enter between the adjacent second signal line 36 and the second ground line 37. In this way, the second bonding layer 62A on one side and the second bonding layer 62B on the other side form the second bonding layer 62. In Figures 3A to 4B, although the interface between the second bonding layer 62A on one side and the second bonding layer 62B on the other side is represented by an imaginary line, this interface is not actually visible. The second bonding layer 62A on one side and the second bonding layer 62B on the other side become a single unit.

[0100] 8.6 Formation of the second through hole 92 and the third through hole 93 As shown in Figure 3B, a second through-hole 92 is formed in the first plating layer 312, the first base layer 311, and the second adhesive layer 62A on one side. Furthermore, the second through-hole 92 in the first porous insulating layer 21 is a second through-hole 24.

[0101] Meanwhile, a third through-hole 93 is formed in the second base layer 331, the second porous insulating layer 22, and the second adhesive layer 62B on the other side. Furthermore, the third through-hole 93 in the second porous insulating layer 22 is a third through-hole 25.

[0102] As a method for forming the second through hole 92 and the third through hole 93, the method for forming the first through hole 91 can be exemplified.

[0103] 8.7 Formation of the second coating layer 313 and the third coating layer 332 Subsequently, as shown in FIG3C, a second plating layer 313 is formed on one side of the first plating layer 312 in the thickness direction and on the inner peripheral surface of the second through hole 92. At the same time, a third plating layer 332 is formed on the other side of the second base layer 331 in the thickness direction and on the inner peripheral surface of the third through hole 93.

[0104] Specifically, before forming the second plating layer 313 and the third plating layer 332, as shown in FIG3B, the first resist layer 95 and the second resist layer 96 are respectively disposed on one side of the first plating layer 312 in the thickness direction and the other side of the second base layer 331 in the thickness direction. Both the first resist layer 95 and the second resist layer 96 are plating resist layers. The first resist layer 95 has a pattern opposite to that of the second plating layer 313. The second resist layer 96 has a pattern opposite to that of the third plating layer 332.

[0105] Subsequently, the resist layer 83, which has a first plating layer 312 with a first resist layer 95 and a second base layer 331 with a second resist layer 96, is immersed in a plating bath to perform a plating process.

[0106] A second plating layer 313 is deposited on one side of the first plating layer 312 exposed from the first resist layer 95 in the thickness direction and on the inner peripheral surface of the second through hole 92. On the other hand, the second plating layer 313 is not deposited on one side of the first plating layer 312 where the first resist layer 95 is disposed in the thickness direction.

[0107] A third plating layer 332 is deposited on the other side of the second base layer 331 exposed from the second resist layer 96 in the thickness direction, and on the inner peripheral surface of the third through hole 93. On the other hand, the third plating layer 332 is not deposited on the other side of the second base layer 331 where the second resist layer 96 is disposed in the thickness direction.

[0108] In this way, a third conductor layer 33 is formed, which has a third grounding portion 38 and a fourth grounding portion 39.

[0109] The third grounding portion 38 is formed from the second base layer 331. Therefore, the thickness T3 of the third grounding portion 38 is the same as the thickness of the second base layer 331.

[0110] The fourth grounding portion 39 is formed by the second base layer 331 and the third plating layer 332. Therefore, the thickness T4 of the fourth grounding portion 39 is the same as the total thickness of the second base layer 331 and the third plating layer 332.

[0111] Subsequently, the first anti-corrosion layer 95 and the second anti-corrosion layer 96 are removed.

[0112] 8.8 Patterning of the first plating layer 312 and the first substrate layer 311 As shown in Figure 4A, the first plating layer 312 and the first base layer 311 are patterned. For example, wet etching and dry etching can be used to pattern the first plating layer 312 and the first base layer 311; wet etching is preferred. This forms the first conductor layer 31 having the first signal line 34 and the first ground line 35 (implementation of the first step).

[0113] The first signal line 34 is formed by a patterned first substrate layer 311 and a patterned first plating layer 312. Therefore, the thickness T1 of the first signal line 34 is the total thickness of the first substrate layer 311 and the first plating layer 312.

[0114] The first grounding wire 35 is formed by a patterned first base layer 311, a patterned first plating layer 312, and a second plating layer 313. Therefore, the thickness T2 of the first grounding wire 35 is the total thickness of the first base layer 311, the first plating layer 312, and the second plating layer 313.

[0115] 8.9 Adhesion of the first overburden lamination 85 and the second overburden lamination 86 As shown in Figure 4B, the first cover laminate 85 is attached to the first conductor layer 31 (implementation of step 2). As shown by the imaginary line, the first cover laminate 85 has a first cover insulating layer 51 and a first adhesive layer 61 sequentially on the other side in the thickness direction.

[0116] At the same time, the second cover laminate 86 is attached to the second conductor layer 32. As shown by the imaginary line, the second cover laminate 86 has a second cover insulating layer 52 and a third adhesive layer 63 sequentially on the side facing the thickness direction.

[0117] The aforementioned pressurizing machine is used in the above bonding process. The pressurizing conditions are the same as described above.

[0118] During the bonding of the first cover layer 85, the first adhesive layer 61 enters between the adjacent first signal line 34 and first ground line 35. The first adhesive layer 61 contacts one side of the first porous insulating layer 21 exposed from the first signal line 34 and the first ground line 35 in the thickness direction.

[0119] In the bonding of the second cover layer 86, the third adhesive layer 63 contacts the other side of the thickness direction of the second porous insulating layer 22 surrounding the third conductor layer 33.

[0120] Based on the above, a wiring circuit board 1 having a porous insulating layer 2, a conductor layer 3, a conductor connection portion 4, a covering insulating layer 5, and an adhesive layer 6 is manufactured.

[0121] Furthermore, as shown in Figure 1, when a reinforcing layer 7 is provided on the wiring circuit board 1, the reinforcing layer 7 is bonded to the second covering insulating layer 52 via the fourth bonding layer 64. The aforementioned pressurizing machine is used for bonding the reinforcing layer 7. The pressurizing conditions are the same as described above.

[0122] 9. Effects of one implementation method In the wiring circuit board 1, the first ground line 35 is thicker than the first signal line 34. In other words, the first signal line 34 is thinner than the first ground line 35.

[0123] Therefore, for example, when the second porous laminate 82 (see Figure 2D) is bonded to the second conductor layer 32, and further when the reinforcing layer 7 is provided on the wiring circuit board 1, if pressure is applied to the first porous insulating layer 21 in the thickness direction, the first porous insulating layer 21 overlapping with the first signal line 34 in the thickness direction receives less pressure than the first porous insulating layer 21 overlapping with the first ground line 35 in the thickness direction. Therefore, compared to the thickness variation of the first porous insulating layer 21 overlapping with the first ground line (second wiring portion) 35 in the thickness direction, the thickness variation of the first porous insulating layer 21 overlapping with the first signal line 34 in the thickness direction can be suppressed more effectively. Specifically, the characteristic impedance mismatch of the first signal line 34 can be suppressed.

[0124] As a result, the changes in the electrical characteristics of the first signal line 34 are suppressed more effectively than the changes in the electrical characteristics of the first grounding line 35.

[0125] On the other hand, although the first porous insulating layer 21 overlapping with the first grounding wire 35 varies greatly, the electrical characteristics of the first grounding wire 35 are allowed to vary greatly because the weak current flowing in the first grounding wire 35 is grounded.

[0126] In the wiring circuit board 1, the third conductor layer 33, serving as a ground layer, includes a third ground portion 38 overlapping the first signal line 34 and a fourth ground portion 39 overlapping the first ground line 35 and being thicker than the third ground portion 38. Therefore, when pressure is applied to the wiring circuit board 1 in the thickness direction, the porous insulating layer 2 (first porous insulating layer 21 and second porous insulating layer 22) overlapping the first signal line 34 in the thickness direction experiences less pressure than the porous insulating layer 2 overlapping the first ground line 35 in the thickness direction. Therefore, the thickness variation of the porous insulating layer 2 overlapping the first signal line 34 in the thickness direction is more effectively suppressed compared to the thickness variation of the porous insulating layer 2 overlapping the first ground line 35 in the thickness direction. Specifically, the characteristic impedance mismatch of the first signal line 34 is more effectively suppressed.

[0127] Furthermore, in the above manufacturing method, as shown in FIG4B, in the step of attaching the first overlay 85 to the first conductor layer 31, even if a large pressure is applied to the porous insulating layers 2 (the first porous insulating layer 21 and the second porous insulating layer 22), as mentioned above, the thickness variation of the porous insulating layer 2 overlapping the first signal line 34 in the thickness direction is suppressed more than the thickness variation of the porous insulating layer 2 overlapping the first ground wire 35 in the thickness direction. As a result, the variation of the electrical characteristics of the first signal line 34 is suppressed more than the variation of the electrical characteristics of the first ground wire 35.

[0128] 10. Variation Examples In the variations, the same reference numerals are used to mark the same components and steps as in the first embodiment, and detailed descriptions are omitted. Furthermore, unless otherwise specified, the variations can achieve the same effects as the first embodiment. Moreover, the first embodiment and its variations can be appropriately combined.

[0129] The first grounding wire 35, the second grounding wire 37, and the third conductor layer 33 can be respectively the first power line, the second power line, and the power layer. The first power line, the second power line, and the power layer together with the second conductor connection portion 42 and the third conductor connection portion 43 form a power path. In the power path, for example, a large current of 1 A or more, and further, 10 A or more, flows.

[0130] As shown in Figure 1, the first signal line 34 is disposed between the two first ground lines 35. Although not shown, in a variation, the first signal line 34 may also be disposed in the first direction on the opposite side of the other first ground line 35 relative to the other first ground line 35. Furthermore, the first signal line 34 may also be disposed in the first direction on the opposite side of one of the first ground lines 35 relative to the other first ground line 35.

[0131] Preferably, the first signal line 34 is positioned between the two first ground lines 35. In this way, when pressure is applied using a pressure plate with a flat plate shape, the porous insulating layer 2 overlapping the two first ground lines 35 in the thickness direction can withstand a relatively large pressure with good balance, thus the porous insulating layer 2 overlapping the first signal line 34 positioned between the two first ground lines 35 is subjected to a smaller pressure. Therefore, compared to the thickness variation of the porous insulating layer 2 overlapping the first ground line 35 in the thickness direction, the thickness variation of the porous insulating layer 2 overlapping the first signal line 34 in the thickness direction is better suppressed.

[0132] Although not shown in the diagram, the first grounding wire (second wiring section) 35 can also be one.

[0133] In the wiring circuit board 1 shown in FIG5, the conductor layer 3 has a first conductor layer 30, which serves as an example of a ground layer. The first conductor layer 30 is disposed on one side of the first porous insulating layer 21 in the thickness direction. The first conductor layer 30 has a first ground portion 301 and a second ground portion 302.

[0134] The first grounding portion 301 is disposed on one side of the first porous insulating layer 21 between the two second through holes 24 in the thickness direction. The first grounding portion 301 extends in the first direction. When projected along the thickness direction, the first grounding portion 301 overlaps with the third grounding portion 38. The first grounding portion 301 has a flat plate shape.

[0135] The other side of the thickness direction of one second grounding portion 302 is connected to one end of the first grounding portion 301 in the first direction. The other side of the thickness direction of the other second grounding portion 302 is connected to the other end of the first grounding portion 301 in the first direction. In this way, the two second grounding portions 302 are electrically connected to each other via the first grounding portion 301.

[0136] Therefore, the first conductor layer 30, the second grounding wire 37, the third conductor layer 33, and the conductor connection portion 4 form a grounding path with a roughly rectangular frame shape when viewed in cross-section. The rectangular frame surrounds the second signal line 36 when viewed in cross-section.

[0137] As shown in Figure 6, the wiring circuit board 1 has a porous insulating layer 2, a conductor layer 3, two bonding layers 6 and a covering insulating layer 5.

[0138] The porous insulating layer 2 is the first porous insulating layer 21. The first porous insulating layer 21 does not have the second through hole 24.

[0139] Conductor layer 3 is the first conductor layer 31.

[0140] Next, layer 6 has a first next layer 61 and a second next layer 62.

[0141] The covering insulation layer 5 is the first covering insulation layer 51.

[0142] In the wiring circuit board 1 shown in Figure 6, a first porous insulating layer 21, a second bonding layer 62, a first conductor layer 31, a first bonding layer 61 and a first covering insulating layer 51 are sequentially disposed on the side facing the thickness direction.

[0143] In the wiring circuit board 1 shown in FIG7, the conductor layer 3 includes the first conductor layer 31 and the third conductor layer 40 described above.

[0144] The third conductor layer 40 has a second signal line 36 and two fourth grounding portions 39.

[0145] Although not illustrated, the porous insulating layer 2 includes a surface layer located at one end and / or the other end in the thickness direction. The surface layer extends in the planar direction. The surface layer is relatively smooth. For example, the first porous insulating layer 21 includes a surface layer disposed at one end and / or the other end in the thickness direction. The second porous insulating layer 22 includes a surface layer at one end and / or the other end in the thickness direction.

[0146] A surface layer located at one end of the first porous insulating layer 21 in the thickness direction forms one side of the first porous insulating layer 21 in the thickness direction. A surface layer located at the other end of the first porous insulating layer 21 in the thickness direction forms the other side of the first porous insulating layer 21 in the thickness direction. The ratio of the thickness of the surface layer to the thickness of the first porous insulating layer 21 is, for example, less than 0.1. The thickness of the surface layer is appropriately adjusted in a manner that ensures the peel strength of the surface layer relative to the first substrate layer 311. Specifically, the thickness of the surface layer is, for example, 1 μm or more, and, for example, 50 μm or less, preferably 30 μm or less.

[0147] A surface layer at one end of the second porous insulating layer 22 in the thickness direction forms one side of the second porous insulating layer 22 in the thickness direction. A surface layer at the other end of the second porous insulating layer 22 in the thickness direction forms the other side of the second porous insulating layer 22 in the thickness direction. The ratio of the thickness of the surface layer to the thickness of the second porous insulating layer 22 is, for example, less than 0.1. The thickness of the surface layer is appropriately adjusted in a way that ensures the peel strength of the surface layer relative to the second adhesive layer 62B on the other side. Specifically, the thickness of the surface layer is, for example, 1 μm or more, or, for example, 50 μm or less, preferably 30 μm or less.

[0148] Although not shown in the diagram, the next layer 6 has a fourth and a fifth bonding layer, which are not shown in the diagram.

[0149] The fourth bonding layer is disposed on one side of the first porous insulating layer 21 in the thickness direction. The fourth bonding layer is interposed between the first porous insulating layer 21 and the first conductor layer 31. The fourth bonding layer bonds the first porous insulating layer 21 and the first conductor layer 31. In this variation, the fourth bonding layer and the second bonding layer 62 (second bonding layer 62A on one side, see Figure 3C) are disposed on one side and the other side of the first porous insulating layer 21 in the thickness direction, respectively.

[0150] The fifth bonding layer is disposed on the other side of the second porous insulating layer 22 in the thickness direction. The fifth bonding layer is interposed between the second porous insulating layer 22 and the third conductor layer 33. The fifth bonding layer bonds the second porous insulating layer 22 and the third conductor layer 33. In this variation, the second bonding layer 62 (the second bonding layer 62B on the other side, see Figure 3C) and the fifth bonding layer are disposed on one side and the other side of the second porous insulating layer 22 in the thickness direction, respectively.

[0151] To manufacture the wiring circuit board 1 of this variation, referring to FIG2A, a first porous laminate 81 is prepared having a second conductor layer 32, a second adhesive layer 62A on one side, a first porous insulating layer 21, a fourth adhesive layer (not shown) and a first base layer 311 in sequence on one side in the thickness direction.

[0152] Referring to the lower side view of FIG2D, a second porous laminate 82 is used, which sequentially comprises a second adhesive layer 62B, a second porous insulating layer 22, a fifth adhesive layer (not shown), and a second base layer 331 on the other side in the thickness direction.

[0153] Furthermore, the above-described invention is provided as an illustrative embodiment of the present invention, but it is merely illustrative and should not be interpreted as limiting. Variations of the present invention that are readily apparent to those skilled in the art are included in the following claims.

[0154] 1: Wiring circuit board 2: Porous insulating layer 3: Conductor layer 4: Conductor connection part 5: Cover with insulation layer 6: Next layer 7: Reinforcement layer 21: First porous insulating layer 22: Second porous insulating layer 23: First through hole 24: Second through hole 25: Third through hole 30: First conductor layer 31: First conductor layer 32: Second conductor layer 33: Third conductor layer (grounding layer) 34: Signal Line 1 (Waiter Section 1) 35: First grounding wire (second wiring section) 36: Signal Line 2 37: Second grounding wire 38: Third grounding section (Third wiring section) 39: Fourth grounding section (fourth wiring section) 40: Third conductor layer (grounding layer) 41: First conductor connection part 42: Second conductor connection 43: Third conductor connection 51: First Cover Insulation Layer 52: Second Cover Insulation Layer 61: The first layer continues 62: The second layer continues 62A: Second adjacent layer 62B: Second layer 63: The third layer 64: The 4th layer 81: First porous mass-forming layer 82: Second porous mass-forming layer 83: Corrosion-resistant laminate 85: First overburden layer 86: Second overburden layer 91: First through hole 92: Second through hole 93: Third through hole 95: First anti-corrosion layer 96: Second anti-corrosion layer 301: First grounding part 302: Second grounding part 311: First basal layer 312: First coating layer 313: Second coating layer 331: Second basal layer 332: Third plating layer 341: Signal terminal 351: Grounding terminal 381: Overlapping parts 382: Non-overlapping parts

Claims

1. A wiring circuit board having a porous insulating layer and a conductor layer sequentially disposed on one side in the thickness direction; and further having a ground layer disposed on the other side in the thickness direction of the porous insulating layer, wherein the conductor layer has a first wiring portion and a second wiring portion that is thicker than the first wiring portion, the ground layer has a third wiring portion that overlaps with the first wiring portion when projected in the thickness direction, and a fourth wiring portion that overlaps with the second wiring portion, the fourth wiring portion being thicker than the third wiring portion, the porous insulating layer having a through hole penetrating the porous insulating layer in the thickness direction; the wiring circuit board further having a conductor connection portion filling the through hole and contacting the conductor layer and the ground layer.

2. The wiring circuit board of claim 1, wherein two of the second wiring portions are arranged at intervals in a direction orthogonal to the thickness direction, and the first wiring portion is arranged between the two second wiring portions.

3. The wiring circuit board of claim 1 or 2 further includes an adhesive layer and a covering insulating layer; and the covering insulating layer covers the conductor layer and the porous insulating layer from the thickness direction side through the adhesive layer.

Images