Wiring circuit substrate and method for manufacturing the same

Abstract

The method for manufacturing a wiring circuit board comprises: a first step, in which a first insulating layer and wiring are prepared, the wiring being arranged on one side in the thickness direction of the first insulating layer, the wiring having one side in the thickness direction arranged opposite to the one side in the thickness direction of the first insulating layer with a gap therebetween, and side surfaces continuous with both end edges of one side in the thickness direction of the wiring and extending from both end edges to the other side in the thickness direction; a second step, in which a second insulating layer is formed on one side in the thickness direction and on the side surfaces of the wiring; and a third step, in which a particle-containing sheet containing conductive particles having an aspect ratio of 2 or more is hot-pressed against the second insulating layer to form a particle-containing layer on the surface of the second insulating layer. The second insulating layer has an indentation hardness of 60 MPa or more at the hot-pressing temperature in the third step as measured by a nanoindentation test.

Description

Technical Field

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

[0002] Conventionally, it is well known that a coil module is used in wireless communication or wireless power transmission for transmitting electric power wirelessly.

[0003] For example, a coil module including a coil pattern and a magnetic layer that buries the coil pattern and contains flat magnetic particles has been proposed (see, for example, Patent Document 1).

[0004] Such a coil module is obtained, for example, by first forming a coil pattern by patterning a conductor, and then hot-pressing a magnetic sheet containing magnetic particles with respect to the coil pattern.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-005115 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, a large current may flow through the coil pattern. In this case, the flat magnetic particles included in the magnetic layer may short-circuit the coil patterns. Therefore, insulation between the coil pattern and the magnetic layer is required.

[0010] Therefore, attempts have been made to form an insulating layer between the coil pattern and the magnetic layer using a resin composition.

[0011] However, the cross-section of the coil pattern is roughly rectangular and includes a ridge portion between the upper surface and the side surface. If an insulating layer is formed on the coil pattern and then a magnetic sheet containing magnetic particles is pressed onto such an insulating layer, the magnetic particles will easily penetrate the portion of the insulating layer corresponding to the ridge portion and eventually come into contact with the ridge portion. As a result, there is a disadvantage that the insulation between the magnetic layer and the coil pattern cannot be ensured due to such contact.

[0012] The present invention provides a wiring circuit board capable of ensuring the insulation of a particle-containing layer with respect to wiring, and a method for producing the same.

[0013] Solutions for solving problems

[0014] The present invention (1) includes a method for manufacturing a wiring circuit substrate, which comprises: a first step, in which a first insulating layer and wiring are prepared, the wiring being arranged on one side in the thickness direction of the first insulating layer, the wiring having a one side in the thickness direction arranged relative to the one side in the thickness direction of the first insulating layer with a gap therebetween, and a side surface continuous with both end edges of the one side in the thickness direction of the wiring and extending from the two end edges to the other side in the thickness direction; a second step, in which a second insulating layer is formed on one side in the thickness direction and the side surface of the wiring; and a third step, in which a particle-containing sheet containing conductive particles having an aspect ratio of 2 or more is hot-pressed relative to the second insulating layer so that a particle-containing layer is formed on the surface of the second insulating layer, the second insulating layer having an indentation hardness of 60 MPa or more at the temperature of hot pressing in the third step as measured by a nanoindentation test.

[0015] In the manufacturing method of the wiring circuit board, at the temperature of the hot pressing in the third step, the indentation hardness of the second insulating layer measured by the nanoindentation test is high, 60 MPa or more, that is, the second insulating layer during hot pressing is hard, so it is possible to suppress the particles of the particle-containing layer from penetrating the second insulating layer during hot pressing. Therefore, the insulation of the particle-containing layer with respect to the wiring can be ensured.

[0016] The present invention (2) includes the method for producing the wired circuit board, wherein the conductive particles are magnetic particles, the particle-containing layer is a magnetic layer, and the particle-containing sheet is a magnetic sheet.

[0017] In this method of manufacturing a wired circuit board, since the particle-containing layer is a magnetic layer, the effective magnetic permeability around the wires can be increased, so that a wired circuit board having a high inductance can be manufactured.

[0018] The present invention (3) includes the method for manufacturing a wired circuit board according to (2), wherein in the second step, the second insulating layer is formed by electrodeposition coating.

[0019] In the manufacturing method of the wiring circuit board, in the second step, since the second insulating layer is formed by electrodeposition coating, a relatively thin second insulating layer can be reliably formed. Therefore, it is possible to suppress the decrease in the effective magnetic permeability of the magnetic layer covering the wiring through such a second insulating layer. As a result, the wiring circuit board has a high inductance.

[0020] On the other hand, when the thickness of the second insulating layer is thin, the magnetic particles easily penetrate the thin second insulating layer and contact the wiring. However, in this wiring circuit substrate, the second insulating layer during hot pressing is relatively hard as described above, so during hot pressing, the magnetic particles can be suppressed from penetrating the second insulating layer, and the insulation of the second insulating layer can be ensured.

[0021] The present invention (4) includes the method for manufacturing a wired circuit board according to (2) or (3), wherein the thickness of the second insulating layer is 10 μm or less.

[0022] In this method of manufacturing a wired circuit board, the thickness of the second insulating layer is as thin as 10 μm or less, so that a decrease in the effective magnetic permeability of the magnetic layer can be suppressed. Therefore, a wired circuit board having a high inductance can be manufactured.

[0023] On the other hand, when the thickness of the second insulating layer is thinner, 10 μm or less, the magnetic particles easily penetrate the thinner second insulating layer and come into contact with the wiring. However, in this wiring circuit board, the second insulating layer during hot pressing is relatively hard as described above, so during hot pressing, the magnetic particles can be prevented from penetrating the second insulating layer, and the insulation of the second insulating layer can be ensured.

[0024] The present invention (5) includes a wiring circuit substrate, which comprises: a first insulating layer; a wiring, which is arranged on one side in the thickness direction of the first insulating layer, the wiring having a one side in the thickness direction arranged relative to the one side in the thickness direction of the first insulating layer with a gap therebetween, and a side surface which is continuous with both end edges of the one side in the thickness direction of the wiring and extends from the two end edges to the other side in the thickness direction; a second insulating layer, which is formed on one side in the thickness direction and the side surface of the wiring; and a particle-containing layer, which contains conductive particles with an aspect ratio of 2 or more and is formed on the surface of the second insulating layer, the second insulating layer having an indentation hardness of 60 MPa or more at 170°C as measured by a nanoindentation test.

[0025] In the wiring circuit board, the indentation hardness of the second insulating layer at 170° C. measured by the nanoindentation test is high, being 60 MPa or more, that is, the second insulating layer is relatively hard, so when the particle-containing layer is formed on the surface of the second insulating layer by hot pressing at 170° C., the particles of the particle-containing layer can be suppressed from penetrating the second insulating layer. Therefore, the insulation of the particle-containing layer with respect to the wiring can be ensured.

[0026] The present invention (6) includes the wired circuit board described in (5), wherein the conductive particles are magnetic particles, the particle-containing layer is a magnetic layer, and the wired circuit board is a magnetic wired circuit board.

[0027] In this magnetic wiring circuit board, since the particle-containing layer is a magnetic layer, the effective magnetic permeability around the wiring can be increased. Therefore, the wiring circuit board has a high inductance.

[0028] Effects of the Invention

[0029] According to the wired circuit board and the method for producing the same of the present invention, the particle-containing layer has excellent insulation properties with respect to the wiring. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A cross-sectional view showing a magnetic wired circuit board according to an embodiment of the wired circuit board of the present invention.

[0031] Figure 2 A~ Figure 2 C is Figure 1 The manufacturing process diagram of the magnetic wiring circuit substrate shown in FIG. Figure 2 A represents a first step of preparing a first insulating layer and a wiring portion, Figure 2 B represents a second step of forming a second insulating layer, Figure 2 C represents the third step of forming a magnetic layer.

[0032] Figure 3 This is a graph showing the relationship between the indentation hardness and the insulation evaluation of the second insulating layer in Examples. DETAILED DESCRIPTION

[0033] <One Implementation Method>

[0034] Reference Figure 1 A magnetic wired circuit board 1 which is one embodiment of the wired circuit board of the present invention will be described.

[0035] The magnetic wiring circuit board 1 has one surface in the thickness direction and the other surface in the thickness direction which are opposite to each other in the thickness direction, and has a sheet shape extending in the plane direction (direction perpendicular to the thickness direction). The magnetic wiring circuit board 1 has a first insulating layer 2, a wiring portion 3 as an example of wiring, a second insulating layer 4, and a magnetic layer 5 as an example of a particle containing layer.

[0036] The first insulating layer 2 has a sheet shape extending in the surface direction. The first insulating layer 2 is a support member for supporting the wiring portion 3 described below, and is also a support layer for supporting the magnetic wiring circuit substrate 1. The first insulating layer 2 has a first insulating surface 7 on one side in the thickness direction and a second insulating surface 8 on the other side in the thickness direction. The first insulating surface 7 and the second insulating surface 8 are each a flat surface along the surface direction.

[0037] As a material of the first insulating layer 2, for example, resins (insulating materials) such as polyimide resins, polyester resins, and acrylic resins can be cited. In addition, the first insulating layer 2 can also be any of a single layer and a multilayer. The thickness of the first insulating layer 2 is not particularly limited, and for example, it is 0.1 μm or more and 1000 μm or less.

[0038] The wiring portion 3 is formed on the first insulating surface 7 of the first insulating layer 2, for example, in the thickness direction and the first direction (equivalent to Figure 1 In a cross section cut in the left-right direction in the plane and included in the plane direction), a plurality of wiring portions 3 are arranged at intervals from each other in the first direction. The shape of the wiring portion 3 when viewed from above (when viewed in the thickness direction) is not particularly limited, and includes, for example, a ring shape (coil shape, etc.).

[0039] The wiring portion 3 includes a first wiring surface 9 which is arranged in the thickness direction relative to the first insulating surface 7 of the first insulating layer 2 at a distance therefrom on one side in the thickness direction, a second wiring surface 10 which is in contact with the first insulating surface 7 of the first insulating layer 2, and a side surface 11 which connects the first and second wiring surfaces 9 and 10 at both ends in the first direction.

[0040] The first wiring surface 9 is a flat surface along the first direction.

[0041] The second wiring surface 10 is disposed opposite to the first wiring surface 9 with a gap therebetween in the thickness direction, and the second wiring surface 10 is a flat surface parallel to the first wiring surface 9 .

[0042] The wiring side surface 11 extends in the thickness direction. In addition, the wiring side surface 11 is continuous with both ends of the first wiring surface 9 in the first direction, extends from both ends of the first wiring surface 9 in the first direction toward the other side in the thickness direction, and is continuous with both ends of the second wiring surface 10 in the first direction. Two wiring side surfaces 11 are provided in one wiring portion 3. The two wiring side surfaces 11 are arranged opposite to each other (opposite to each other) with a gap therebetween in the first direction.

[0043] In addition, the wiring portion 3 has a corner portion 21. The corner portion 21 is a ridge portion formed by the first wiring surface 9 and the wiring side surface 11 in the wiring portion 3. Two corner portions 21 are formed in each wiring portion 3.

[0044] Examples of the material of the wiring portion 3 include conductors such as metals such as copper, nickel, gold, and solder, and alloys of these metals, and preferably copper is used.

[0045] The thickness of the wiring portion 3 is the length between the first wiring surface 9 and the second wiring surface 10 , and specifically, is, for example, 10 μm or more, preferably 30 μm or more, and, for example, 500 μm or less, preferably 250 μm or less.

[0046] The width of the wiring portion 3 is the length between two opposing wiring side surfaces 11 , and is, for example, 20 μm or more, preferably 50 μm or more, and, for example, 2000 μm or less, preferably 1000 μm or less.

[0047] The interval between adjacent wiring portions 3 is, for example, greater than or equal to 20 μm, or preferably greater than or equal to 50 μm, and, for example, less than or equal to 2000 μm, or preferably less than or equal to 1000 μm.

[0048] The wiring portion 3 is provided together with the first insulating layer 2 described above on a wiring circuit board preparation body 6 described later (see in particular Figure 2 A).

[0049] A plurality of second insulating layers 4 are provided corresponding to the plurality of wiring portions 3. Specifically, one second insulating layer 4 is provided for one wiring portion 3, that is, the second insulating layer 4 and the wiring portion 3 are provided in a one-to-one correspondence. The second insulating layer 4 is formed in a thin film along the first wiring surface 9 and the wiring side surface 11 (including the corner portion 21) of the wiring portion 3. The second insulating layer 4 has a shape that is open to the other side in the thickness direction and is substantially in the shape of a Japanese kana U (letter U) when viewed in cross section.

[0050] The second insulating layer 4 integrally includes an insulating upper wall 12 , insulating side walls 26 , and an insulating corner portion 13 .

[0051] The insulating upper wall 12 has a substantially straight line shape along the first wiring surface 9 in a cross-sectional view.

[0052] The insulating side wall 26 has a substantially straight line shape along the wiring side surface 11 in a cross-sectional view.

[0053] The insulating corner portion 13 connects one end edge of the insulating upper wall 12 in the first direction and one end edge in the thickness direction of the insulating side wall 26 on one side in the first direction. In addition, the insulating corner portion 13 connects the other end edge of the insulating upper wall 12 in the first direction and one end edge in the thickness direction of the insulating side wall 26 on the other side in the first direction. The insulating corner portion 13 faces the corner portion 21 of the wiring portion 3, thereby contacting and covering the corner portion 21.

[0054] In addition, the second insulating layer 4 has an insulating surface 16 that is spaced apart from the wiring portion 3. The insulating surface 16 of the insulating upper wall 12 is spaced apart from the first wiring surface 9 and is arranged on the upper side of the first wiring surface 9. The insulating surface 16 of the insulating side wall 26 is spaced apart from the wiring side surface 11 and is spaced apart from the wiring side surface 11 and is arranged on the first direction outer side (the side away from the wiring portion 3) of the wiring side surface 11. The insulating surface 16 of the insulating corner portion 13 is spaced apart from the corner portion 21 and is spaced apart from the corner portion 21 and is arranged on the first direction outer side of the corner portion 21 that is inclined in one direction in the thickness direction.

[0055] The second insulating layer 4 is, for example, an electrodeposited layer, a coating layer, etc., and is preferably an electrodeposited layer. In addition, "electrodeposition" and "coating" will be described in the subsequent production method.

[0056] The second insulating layer 4 has no magnetism, for example.

[0057] As the material of the second insulating layer 4, a resin that does not contain magnetic particles 18 (described in detail in the magnetic layer 5 later) can be cited. As the resin of the second insulating layer 4, a resin that is ionic in water is preferably cited, and specifically, a thermoplastic resin such as an acrylic resin, an epoxy resin, a thermosetting resin such as a thermosetting polyimide resin is cited. These resins can be used alone or in combination. Preferably, a thermosetting resin is cited, and more preferably, an epoxy resin is cited. In addition, the epoxy resin includes an imide-epoxy resin.

[0058] The indentation hardness H of the second insulating layer 4 at 170° C. measured by the nanoindentation test 170℃ It is 60 MPa or more, preferably 80 MPa or more, more preferably 90 MPa or more, further preferably 100 MPa or more, and, for example, is 500 MPa or less.

[0059] If the indentation hardness H of the second insulating layer 4 at 170°C 170℃ If the indentation hardness H of the second insulating layer 4 is less than the above lower limit, when the hot pressing of the magnetic sheet 17 described later is performed at a temperature of 170°C or higher (e.g., a high temperature of more than 170°C and less than 200°C, or even less than 190°C), the magnetic particles 18 of the magnetic sheet 17 penetrate the second insulating layer 4. In other words, if the indentation hardness H of the second insulating layer 4 at 170°C is less than the above lower limit, the magnetic particles 18 of the magnetic sheet 17 penetrate the second insulating layer 4. 170℃ When the temperature is not less than the above lower limit, even when the magnetic sheet 17 is hot-pressed at a temperature of 170° C. or higher, it is possible to suppress the magnetic particles 18 of the magnetic sheet 17 from penetrating the second insulating layer 4 .

[0060] In addition, the indentation hardness H of the second insulating layer 4 at 110° C. measured by the nanoindentation test is 110℃ For example, it is 60 MPa or more, preferably 80 MPa or more, more preferably 90 MPa or more, further preferably 175 MPa or more, particularly preferably 200 MPa or more, and for example, it is 750 MPa or less.

[0061] If the indentation hardness H of the second insulating layer 4 at 110°C 110℃ If it is above the above lower limit, when the magnetic sheet 17 described later is hot-pressed at a temperature of 110°C or slightly above 110°C (for example, above 110°C and below 130°C, or even at a low temperature below 120°C), it is possible to suppress the magnetic particles 18 of the magnetic sheet 17 from penetrating the second insulating layer 4.

[0062] In addition, in the second insulating layer 4, in the measurement temperature range of 100°C to 200°C, the indentation hardness at a lower measurement temperature is higher than the indentation hardness at a higher measurement temperature. Therefore, the indentation hardness H of the second insulating layer 4 at 110°C is 110℃ The indentation hardness H of the second insulating layer 4 at 170°C 170℃ The ratio (H 110℃ / H 170℃ ) is, for example, greater than 1, even greater than 1.25, even greater than 1.75, even greater than 2, and, for example, less than 5, even less than 3.

[0063] In the nanoindentation test, the nanoindenter (indenter) is directly pressed into the second insulating layer 4 to obtain the indentation hardness H 170℃ and H 110℃ .

[0064] The second insulating layer 4 is relatively thin, and its average thickness is, for example, 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, further preferably 7.5 μm or less, particularly preferably 5 μm or less, and, for example, 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more.

[0065] When the thickness of the second insulating layer 4 is thin and equal to or less than the above upper limit, the effective magnetic permeability of the magnetic layer 5 described below can be increased, and the inductance of the magnetic wired circuit board 1 can be increased.

[0066] On the other hand, when the second insulating layer 4 is too thin, magnetic grains 18 of the magnetic layer 5 described later are likely to penetrate the second insulating layer 4 and come into contact with the wiring portion 3 .

[0067] However, in the magnetic wiring circuit board 1, since the second insulating layer 4 has the high indentation hardness as described above, even if the second insulating layer 4 is too thin, the second insulating layer 4 can be prevented from being penetrated by the magnetic particles 18, and the insulation property of the second insulating layer 4 can be ensured.

[0068] The magnetic layer 5 is provided on the magnetic wired circuit board 1 in order to increase the inductance of the magnetic wired circuit board 1. The magnetic layer 5 has a sheet shape extending in the surface direction.

[0069] The magnetic layer 5 buries the wiring portion 3 via the second insulating layer 4. Specifically, the magnetic layer 5 covers the first wiring surface 9 and the wiring side surface 11 (including the corner 21) of the wiring portion 3 via the second insulating layer 4. The magnetic layer 5 is in contact with the insulating surface 16 of the second insulating layer 4. In other words, the magnetic layer 5 is directly formed on the insulating surface 16. In addition, the magnetic layer 5 covers the exposed surface 36 of the first insulating surface 7 of the first insulating layer 2 that is exposed from the second insulating layer 4.

[0070] The magnetic layer 5 has a first magnetic surface 14 and a second magnetic surface 15 .

[0071] The first magnetic surface 14 is disposed on one side in the thickness direction with a gap therebetween with respect to the second insulating layer 4 facing the first wiring surface 9. The first magnetic surface 14 is exposed on one side in the thickness direction.

[0072] The second magnetic surface 15 is arranged at a distance from the first magnetic surface 14 on the other side in the thickness direction. The second magnetic surface 15 is in contact with the insulating surface 16 of the second insulating layer 4 and the exposed surface 36 of the first insulating layer 2 .

[0073] The magnetic layer 5 contains magnetic particles 18. Specifically, as a material of the magnetic layer 5, for example, a magnetic composition containing magnetic particles 18 having an aspect ratio of 2 or more and a resin component 19 can be cited.

[0074] Examples of the magnetic particles 18 include soft magnetic particles 18 such as sendust. Examples of the shape of the magnetic particles 18 include a thin flat shape (plate shape) with a large surface, such as a needle shape, and the like.

[0075] The aspect ratio of the magnetic particles is 2 or more, preferably 5 or more, more preferably 10 or more, further preferably 20 or more, and 100 or less.

[0076] When the magnetic particles 18 are flat, the flatness (flatness) is, for example, 8 or more, preferably 15 or more, and, for example, 500 or less, preferably 450 or less. The flatness is, for example, the value of the aspect ratio obtained by dividing the average particle diameter (average length) of the magnetic particles 18 by the average thickness of the magnetic particles 18.

[0077] The proportion of the magnetic particles 18 contained in the magnetic layer 5 (magnetic composition) is, for example, 50 volume % or more, preferably 55 volume % or more, and, for example, 95 volume % or less, preferably 90 volume % or less.

[0078] The resin component 19 includes, for example, a thermosetting resin such as an epoxy resin composition containing an epoxy resin, a curing agent, and a curing accelerator. Such a magnetic composition is described in, for example, Japanese Patent Application Laid-Open No. 2017-005115 and Japanese Patent Application Laid-Open No. 2015-092543.

[0079] The maximum thickness of the magnetic wired circuit board 1 is, for example, 30 μm or more, preferably 50 μm or more, and, for example, 1000 μm or less, preferably 800 μm or less.

[0080] Next, refer to Figure 2 A~ Figure 2C will now describe a method for manufacturing the magnetic wired circuit board 1.

[0081] The method for manufacturing the magnetic wiring circuit board 1 includes a first step of preparing the first insulating layer 2 and the wiring portion 3 (see Figure 2 A) The second step of forming the second insulating layer 4 (see Figure 2 B) and the third step of forming the magnetic layer 5 (refer to Figure 2 C and Figure 1 ).

[0082] like Figure 2 As shown in FIG. 1A, in the first step, a wiring circuit substrate preparation body 6 having a first insulating layer 2 and a wiring portion 3 is prepared. The wiring circuit substrate preparation body 6 does not yet have a second insulating layer 4 and a magnetic layer 5, but has a first insulating layer 2 and a wiring portion 3. Preferably, the wiring circuit substrate preparation body 6 is composed of only the first insulating layer 2 and the wiring portion 3.

[0083] For example, the above-mentioned resin film or the like is prepared as the first insulating layer 2, and then the wiring portion 3 is formed on the first insulating surface 7 of the first insulating layer 2 by a known conductor patterning method. Thus, the wired circuit board preparation body 6 is prepared.

[0084] Then, if Figure 2 As shown in B, in the second step, the second insulating layer 4 is formed on the above-mentioned wired circuit board preparation body 6. Specifically, the first wiring surface 9 and the wiring side surface 11 of the wiring portion 3 are covered with the second insulating layer 4.

[0085] Examples of a method for forming the second insulating layer 4 include electrodeposition coating (electrodeposition) and coating such as printing.

[0086] In the electrodeposition coating, the wiring circuit substrate preparation body 6 (the magnetic wiring circuit substrate 1 in the manufacturing process) is immersed in the electrodeposition liquid containing the above-mentioned resin (specifically, the electrodeposition paint), and then an electric current is applied to the wiring part 3, so that the resin coating is precipitated on the first wiring surface 9 and the wiring side surface 11 of the wiring part 3.

[0087] The electrodeposition time is appropriately set depending on the proportion of the resin in the electrodeposition solution, the applied current, etc., and is, for example, 1 minute or more, preferably 2 minutes or more, more preferably 3 minutes or more, and, for example, 20 minutes or less, preferably 10 minutes or less.

[0088] The second insulating layer 4 is formed as an electrodeposited layer by electrodeposition coating. If the resin contains a thermosetting resin, the second insulating layer 4 is, for example, in the B stage (semi-cured). Then, if the second insulating layer 4 is a thermosetting resin in the B stage, the second insulating layer 4 is heated by sintering to be cured (C stage, fully cured).

[0089] In printing as an example of coating, a varnish containing the above-mentioned resin is coated (screen printing) via a screen on the first wiring surface 9 and wiring side surface 11 of the wiring portion 3. Then, when the coating is in the B stage, it is cured by heating.

[0090] The heating temperature (curing temperature) is not particularly limited, and is, for example, 100° C. or higher, preferably 150° C. or higher, and, for example, 250° C. or lower, preferably 225° C. or lower.

[0091] As a method for forming the second insulating layer 4 , electrodeposition coating is preferably used.

[0092] If electrodeposition coating is adopted, the thickness of the second insulating layer 4 can be reduced (the thickness is set to a degree that can ensure the insulation of the second insulating layer 4). In addition, if electrodeposition coating is adopted, the exposed surface 36 of the second insulating layer 4 can be reliably exposed. Therefore, between adjacent wiring portions 3, in the subsequent third step, the magnetic layer 5 can be arranged in the entire thickness direction, so that the effective magnetic permeability of the magnetic layer 5 can be increased, and the inductance of the magnetic wiring circuit board 1 becomes higher.

[0093] Then, if Figure 2 As shown in C, in the third step, the magnetic layer 5 is formed on the wiring circuit board preparation body 6. Specifically, the first wiring surface 9 and the wiring side surface 11 of the wiring portion 3 are covered with the magnetic layer 5 via the second insulating layer 4.

[0094] First, in the third step, Figure 2 As shown in FIG. 1B, a magnetic sheet 17 is prepared as an example of a particle-containing sheet. To prepare the magnetic sheet 17, for example, a magnetic composition containing the above-mentioned magnetic particles 18 and a resin component 19 (preferably a thermosetting resin in the B stage) is formed into a sheet shape. In the magnetic sheet 17, the magnetic particles 18 are oriented (arranged) along the surface direction (direction perpendicular to the thickness direction) of the magnetic sheet 17, for example.

[0095] Then, if Figure 2As shown by the arrow C, the magnetic sheet 17 is hot pressed against the second insulating layer 4 of the wiring circuit substrate preparation body 6. The magnetic sheet 17 is arranged on one side of the wiring circuit substrate preparation body 6 in the thickness direction (specifically, the insulating upper wall 12 of the second insulating layer 4), and the magnetic sheet 17 is hot pressed against one side of the wiring circuit substrate preparation body 6 in the thickness direction (the insulating upper wall 12 of the second insulating layer 4). Specifically, a pressing device 25 having a lower pressing plate 23 and an upper pressing plate 24 is prepared, and the wiring circuit substrate preparation body 6 and the magnetic sheet 17 are set in the pressing device 25. Specifically, the first insulating layer 2 is placed on the lower pressing plate 23, and the magnetic sheet 17 is arranged on one side of the second insulating layer 4 in the thickness direction opposite to the second insulating layer 4. Then, hot pressing is performed in a manner that the upper pressing plate 24 is brought close to the lower pressing plate 23 (the upper pressing plate 24 is lowered).

[0096] During the hot pressing, the magnetic sheet 17 is heated using a heat source (not shown) provided in the pressing device 25 (specifically, the upper pressing plate 24). The temperature of the hot pressing is higher than the temperature at which the magnetic sheet 17 is sufficiently softened, but lower than the temperature at which the second insulating layer 4 is not excessively softened. Specifically, the temperature of the hot pressing of the magnetic sheet 17 allows a slight softening of the second insulating layer 4, but is lower than the temperature at which the hardness of the magnetic particles 18 can be maintained during the hot pressing to a degree that the second insulating layer 4 does not penetrate.

[0097] Furthermore, considering that the indentation hardness of the second insulating layer 4 is higher at a lower temperature, the temperature of the hot pressing is preferably relatively low.

[0098] Specifically, the temperature of hot pressing is, for example, 200°C or less, preferably 190°C or less, more preferably 170°C or less, 150°C or less, 130°C or less, 120°C or less, or 110°C or less, and, for example, 60°C or more, even 80°C or more, or even 100°C or more.

[0099] On the other hand, regarding the indentation hardness of the second insulating layer 4 measured at the above-mentioned hot pressing temperature, specifically, the indentation hardness of the second insulating layer 4 measured by a nanoindentation test at the hot pressing temperature of the third step is 60 MPa or more, preferably 80 MPa or more, more preferably 90 MPa or more, further preferably 100 MPa or more, and, for example, 500 MPa or less.

[0100] If the indentation hardness of the second insulating layer 4 during hot pressing in the third step is lower than the above lower limit, the magnetic particles 18 of the magnetic sheet 17 will penetrate the second insulating layer 4 during hot pressing in the third step. In other words, if the indentation hardness of the second insulating layer 4 during hot pressing in the third step is greater than the above lower limit, the magnetic particles 18 of the magnetic sheet 17 can be suppressed from penetrating the second insulating layer 4 during hot pressing in the third step.

[0101] The indentation hardness of the second insulating layer 4 at the above-mentioned hot pressing temperature includes the indentation hardness H of the second insulating layer 4 at 170° C. 170℃ and the indentation hardness H of the second insulating layer 4 at 110°C 110℃ Specifically, the indentation hardness of the second insulating layer 4 when hot pressing is performed at a temperature of 110° C. corresponds to an indentation hardness H 110℃ The indentation hardness of the second insulating layer 4 when hot pressing is performed at a temperature of 170°C is equivalent to the indentation hardness H 170℃ .

[0102] Thus, the magnetic sheet 17 buries the wiring portion 3 via the second insulating layer 4. Specifically, the magnetic sheet 17 covers the first wiring surface 9 (including the corner portion 21) of the wiring portion 3 via the second insulating layer 4, and enters (sinks) into the area between the wiring side surfaces 11 of the wiring portions 3 adjacent to each other (the portion opposite to the exposed surface 36), filling the area (part) between the wiring side surfaces 11 of the wiring portions 3 adjacent to each other.

[0103] For example, in the magnetic sheet 17 before and after hot pressing, the orientation direction (specifically, the surface direction) of the magnetic particles 18 relative to the insulating upper wall 12 does not change. In addition, in the magnetic sheet 17 before and after hot pressing, the orientation direction (specifically, the surface direction) of the magnetic particles 18 relative to the central portion in the first direction of the exposed surface 36 does not change. On the other hand, in the magnetic sheet 17 before and after hot pressing, the orientation direction (specifically, the surface direction) of the magnetic particles 18 relative to the insulating corner portion 13 and the insulating side wall 26 is along the insulating surface 16 of the insulating corner portion 13 and the insulating side wall 26.

[0104] Thus, the magnetic sheet 17 is formed (shaped) so as to cover the magnetic layer 5 of the wiring portion 3 via the second insulating layer 4 .

[0105] Thus, the magnetic wiring circuit board 1 having the wiring circuit board preparation body 6 and the magnetic layer 5 is produced. The magnetic wiring circuit board 1 is preferably composed of only the wiring circuit board preparation body 6 and the magnetic layer 5 .

[0106] Then, when the magnetic layer 5 contains a thermosetting resin in a B-stage state, the magnetic layer 5 is brought to a C-stage state (completely cured) by, for example, heating, as necessary.

[0107] In addition, Figure 1 and Figure 2 In the magnetic wiring circuit board 1 shown in C, the second insulating layer 4 is covered with the magnetic layer 5, and the indentation hardness H of the second insulating layer 4 at 170°C is 170℃ Measured from the cross section of the magnetic wiring circuit substrate 1. This value is the same as that of the substrate that has not been covered by the magnetic layer 5 during the manufacturing process. Figure 2The indentation hardness H of the second insulating layer 4 at 170°C shown in B 170℃ The indentation hardness H of the second insulating layer 4 at 110°C is 110℃ It's the same situation.

[0108] The magnetic wired circuit board 1 is used in, for example, wireless power transmission (wireless power supply and / or wireless power reception), wireless communication, sensors, passive components, and the like.

[0109] Furthermore, in the manufacturing method of the magnetic wiring circuit board 1, at the temperature of the hot pressing in the third step, the indentation hardness of the second insulating layer 4 measured by the nanoindentation test is high, being 60 MPa or more, that is, the second insulating layer 4 during the hot pressing is relatively hard, and therefore, during the hot pressing, it is possible to suppress the magnetic particles 18 of the magnetic layer 5 from penetrating the second insulating layer 4. Therefore, the insulation of the magnetic layer 5 with respect to the wiring can be ensured.

[0110] In addition, in the method for manufacturing the magnetic wired circuit board 1, the effective magnetic permeability around the wiring portion 3 can be increased by the magnetic layer 5. Therefore, the magnetic wired circuit board 1 having high inductance can be manufactured.

[0111] In addition, in the manufacturing method of the magnetic wiring circuit board 1, in the second step, if the second insulating layer 4 is formed by electrodeposition coating, it is possible to reliably form a relatively thin second insulating layer 4. Therefore, it is possible to suppress a decrease in the effective magnetic permeability of the magnetic layer 5 covering the wiring portion 3 via such a second insulating layer 4. As a result, the magnetic wiring circuit board 1 has a high inductance.

[0112] On the other hand, when the thickness of the second insulating layer 4 is thin, the magnetic particles 18 easily penetrate the thin second insulating layer 4 and contact the wiring portion 3. However, in the magnetic wiring circuit board 1, the second insulating layer 4 is hard as described above, so it is possible to suppress the magnetic particles 18 from penetrating the second insulating layer 4, and the insulation of the second insulating layer 4 can be ensured.

[0113] In the magnetic wired circuit board 1, the thickness of the second insulating layer 4 is as thin as 10 μm or less, so it is possible to suppress a decrease in the effective magnetic permeability of the magnetic layer 5. Therefore, it is possible to manufacture a wired circuit board 1 having a high inductance.

[0114] In addition, in the magnetic wiring circuit substrate 1, the second insulating layer 4 is relatively hard as described above, so even if the thickness of the second insulating layer 4 is relatively thin, for example, less than 10 μm, the magnetic particles 18 can be prevented from penetrating the second insulating layer 4, thereby ensuring the insulation of the second insulating layer 4.

[0115] In the magnetic wiring circuit substrate 1, the indentation hardness of the second insulating layer 4 at 170°C measured by the nanoindentation test is high, being 60 MPa or more, that is, the second insulating layer 4 is hard when the magnetic layer 5 is formed by hot pressing at 170°C, and therefore, it is possible to suppress the magnetic particles 18 of the magnetic layer 5 from penetrating the second insulating layer 4. Therefore, the insulation of the magnetic layer 5 with respect to the wiring portion 3 can be ensured.

[0116] In addition, in the magnetic wired circuit board 1, the effective magnetic permeability around the wiring portion 3 can be increased by the magnetic layer 5. Therefore, the magnetic wired circuit board 1 has a high inductance.

[0117] <Modification>

[0118] In the following modifications, the same reference numerals are used for the same components and processes as those in the above-mentioned embodiment, and detailed description thereof is omitted. In addition, the modifications can be appropriately combined. Moreover, the modifications can have the same effects as those in the embodiment except for the contents specially recorded.

[0119] In one embodiment, as an example of the wired circuit board of the present invention, a magnetic wired circuit board 1 having a magnetic layer 5 is described. However, the present invention is not limited thereto, and a wired circuit board having a particle-containing layer other than the magnetic layer 5 may also be described, although this is not shown.

[0120] The particle-containing layer contains conductive particles other than the above-mentioned magnetic particles at an appropriate ratio. The conductive particles are not particularly limited, and examples thereof include metal particles such as copper particles, silver particles, gold particles, iron particles, and solder particles.

[0121] In one embodiment, the magnetic particles 18 are oriented along the surface direction of the magnetic sheet 17 , but the orientation direction of the magnetic sheet 17 is not particularly limited.

[0122] [Example]

[0123] Embodiment and comparative example are shown below, and the present invention is further specifically described. In addition, the present invention is not limited to any embodiment and comparative example. In addition, the specific numerical values ​​such as the blending ratio (ratio), physical property value, parameter used in the following description can be replaced by the upper limit (defined as "below", "less than" numerical value) or lower limit (defined as "above", "exceeding" numerical value) of the corresponding description of the blending ratio (ratio), physical property value, parameter, etc. recorded in the above-mentioned "specific embodiments" corresponding to them.

[0124] Example 1

[0125] like Figure 2As shown in A, a wired circuit board preparation body 6 having a first insulating layer 2 with a thickness of 5 μm and a wiring portion 3 with a thickness of 100 μm and a width of 335 μm is prepared. The first insulating layer 2 is made of polyimide resin, and the wiring portion 3 is made of copper.

[0126] Then, if Figure 2 As shown in FIG. 1B, the second insulating layer 4 is arranged on the wiring portion 3. Specifically, the second insulating layer 4 as an electrodeposited layer is arranged on the first wiring surface 9 and the wiring side surface 11 by electrodeposition coating using an electrodeposition paint composed of epoxy resin (Elecoat (Japanese: エレコート) PI-A, imide-epoxy resin, manufactured by Shimizu Co., Ltd.). The thickness of the second insulating layer 4 is 5 μm, which is the B stage. Then, the second insulating layer 4 is dried at 110° C. for 5 minutes, and then heated (sintered, fired) at 210° C. for 70 minutes. The second insulating layer 4 is in the C stage.

[0127] Then, if Figure 2 As shown in C, a magnetic sheet 17 having a thickness of 100 μm was prepared from the magnetic composition described in Table 1, and the magnetic sheet 17 was heat-pressed against the second insulating layer 4 at 110° C. for 15 minutes.

[0128] Thus, the magnetic layer 5 in the B-stage state is arranged on the wiring circuit board preparation body 6 .

[0129] In this way, the magnetic wired circuit board 1 is manufactured.

[0130] Example 2 to Comparative Example 2

[0131] A magnetic wiring circuit board 1 was manufactured in the same manner as in Example 1 except that the type of the electrodeposition paint in the second step, the firing time (heating time), and the measurement temperature of the hot press in the second step were changed according to Tables 2 and 3.

[0132] <Evaluation>

[0133] The following items were evaluated. Figure 3 The results are shown in FIG.

[0134] Indentation hardness

[0135] The indentation hardness of the second insulating layer 4 was measured by a nanoindentation test. The measurement target was the second insulating layer 4 in the C stage before the magnetic layer 5 was formed.

[0136] In the nanoindentation test, the nanoindenter (probe, indenter) is pressed into the second insulating layer 4 (specifically, the second insulating layer 4 arranged on the first wiring surface 9), and the displacement-load hysteresis curve obtained thereby is numerically processed using the software (triboscan) included with the measuring device, thereby obtaining the indentation hardness.

[0137] The nanoindenter apparatus and measurement conditions are as follows.

[0138] Nanoindenter device: "Tribo Indenter", manufactured by Hysitron Inc.

[0139] Measuring method: Single indentation method

[0140] Pressing speed: 60μN / sec

[0141] Maximum pressing force: 300μN

[0142] Maximum pressing force holding time: 2 seconds

[0143] Probe: Triangular pyramid type (Triangular pyramid type (Japanese: バーコビッチ type))

[0144] Insulation evaluation

[0145] A probe connected to a digital multimeter (manufactured by ADVANTEST, “R6552 DIGITAL MULTIMETER”) was brought into contact with the evaluation pad portion of the wiring portion 3 not covered by the magnetic layer 5 and the magnetic layer 5 covering the wiring portion 3, respectively, and the presence or absence of conduction was confirmed based on the resistance value of the digital multimeter in the two-terminal resistance mode.

[0146] When there is conduction, some values ​​(digits) are displayed on the liquid crystal display of the digital multimeter.

[0147] On the other hand, when there is no conduction, ".OL" (meaning OverLoad) is displayed on the liquid crystal display of the digital multimeter.

[0148] The above-described conduction check was performed on each of the plurality of wiring portions 3 produced in each of the examples and the comparative examples, and the ratio (percentage) of the wiring portions without conduction was determined.

[0149] Thus, the insulation property of the magnetic layer 5 with respect to the wiring portion 3 was evaluated.

[0150]

Table 1

[0151]

[0152]

Table 2

[0153]

[0154]

Table 3

[0155]

[0156] In addition, the above invention is provided as an exemplary embodiment of the present invention, but this is only an example and should not be interpreted as limiting. Modifications of the present invention that are clear to those skilled in the art are included in the above claims.

[0157] Industrial Applicability

[0158] Wiring circuit substrates are used in wireless power transmission, wireless communications, sensors, passive components, etc.

[0159] Description of Reference Numerals

[0160] 1. Magnetic wiring circuit substrate; 2. First insulating layer; 3. Wiring portion; 4. Second insulating layer; 5. Magnetic layer; 7. First insulating surface; 9. First wiring surface; 11. Wiring side surface; 17. Magnetic sheet; 18. Magnetic particles.

Claims

1. A method for manufacturing a wiring circuit substrate, characterized in that: The manufacturing method of the wiring circuit substrate comprises: A first step, in which a first insulating layer and wiring are prepared, wherein the wiring is arranged on a first insulating surface of the first insulating layer located on one side in the thickness direction, and the wiring has a first wiring surface arranged opposite to the first insulating surface with a gap therebetween, and side surfaces that are continuous with both end edges of the first wiring surface of the wiring and extend from the both end edges to the other side in the thickness direction; a second step of forming a second insulating layer on the first wiring surface and the side surface of the wiring; as well as a third step of hot-pressing a particle-containing sheet containing conductive particles having an aspect ratio of 2 or more against the second insulating layer to form a particle-containing layer on a surface of the second insulating layer; The material of the second insulating layer is resin, The second insulating layer has an indentation hardness of 60 MPa or more and 500 MPa or less at the temperature of the hot pressing in the third step, as measured by a nanoindentation test.

2. The method for manufacturing a wired circuit board according to claim 1, wherein: The conductive particles are magnetic particles, The particle-containing layer is a magnetic layer, The particle-containing sheet material is a magnetic sheet material, The method for manufacturing a wiring circuit substrate is a method for manufacturing a magnetic wiring circuit substrate.

3. The method for manufacturing a wired circuit board according to claim 2, wherein: In the second step, the second insulating layer is formed by electrodeposition coating.

4. The method for manufacturing a wired circuit board according to claim 3, wherein: The second insulating layer has a thickness of 10 μm or less.

5. A wiring circuit substrate, characterized in that: The wiring circuit substrate has: 1st insulating layer; a wiring arranged on a first insulating surface of the first insulating layer located on one side in the thickness direction, the wiring having a first wiring surface arranged opposite to the first insulating surface with a gap therebetween, and side surfaces continuous with both end edges of the first wiring surface of the wiring and extending from the both end edges to the other side in the thickness direction; a second insulating layer formed on the first wiring surface and the side surface of the wiring; and a particle-containing layer containing conductive particles having an aspect ratio of 2 or more and formed on a surface of the second insulating layer, The material of the second insulating layer is resin, The second insulating layer has an indentation hardness of 60 MPa or more and 500 MPa or less at 170° C. as measured by a nanoindentation test.

6. The wiring circuit substrate according to claim 5, wherein: The conductive particles are magnetic particles, The particle-containing layer is a magnetic layer, The wiring circuit substrate is a magnetic wiring circuit substrate.

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