JP2010062464A - Method of manufacturing inductor-incorporated printed wiring board, and inductor-incorporated printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an inductor-incorporated printed wiring board which is reducible in resistance of interlayer wiring even when an inductor wiring layer is made thick. <P>SOLUTION: The method of manufacturing the inductor-incorporated printed wiring board 1 comprises: a stage of manufacturing a lower layer base 4 for an inductor, the stage including forming a copper wiring layer 32 on an insulating layer 31; a stage of manufacturing an upper layer base 5 for the inductor, the stage including forming a copper wiring layer 42 on an upper surface of a magnetic layer 41, forming an adhesion layer 43 on a lower surface of the magnetic layer 41, forming a via hole 45 penetrating the magnetic layer 41 and adhesion layer 43, and forming interlayer wiring 44 electrically connected to the copper wiring layer 42 in the via hole 45; and a laminating stage of positioning and laminating the base 4 and base 5, and pressing them under air pressure below the atmospheric pressure to form the inductor of the copper wiring 32, copper wiring layer 42, and interlayer wiring 44 while connecting the interlayer wiring 44 and copper wiring layer 32 together. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a printed wiring board with a built-in inductor having a multilayer structure in which a plurality of wiring layers are laminated, and a printed wiring board with a built-in inductor.

  In recent years, electronic devices such as personal computers, portable information devices, and electronic exchanges have been required to be reduced in size, and electronic components used therefor have been increasingly demanded for reduction in size, thickness, weight, and cost. However, in power supply circuits for supplying power, downsizing and thinning are delayed due to required characteristics and problems of heat generation. The reason is that a smoothing choke coil and a smoothing capacitor externally attached to the IC are relatively large.

  Patent Document 1 discloses a printed circuit board in which a solenoid inductor is built in a DC-DC converter module. Specifically, a solenoid inductor is formed using circuit wiring of a printed circuit board in which a through hole is formed. An inductance value necessary for smoothing is obtained by enclosing a magnetic body in the solenoid inductor.

Patent Document 2 discloses a printed circuit board including a toroidal inductor. The printed circuit board includes a plurality of wiring layers including an inductor wiring layer. The plurality of wiring layers are stacked by a build-up method. In this wiring circuit board, the wiring layer and the wiring layer are electrically connected by a filled via (interlayer wiring) embedded in the via hole by a plating method.
JP 2005-124271 A JP 2004-193319 A

  A coil used for a power supply circuit is required to have a high inductance value and a low DC resistance value. Here, in the techniques of Patent Documents 1 and 2 in order to reduce the direct current resistance, when the inductor wiring layer is thickened, the insulating layer for embedding it must be thickened, and the diameter of the via hole must be increased. As a result, the interface between the filled via and the wiring layer becomes large, and voids formed at the interface increase. As a result, there is a problem that the resistance at the interface between the filled via and the wiring layer is increased.

  The present invention has been made to solve the above-described problems, and provides a method for manufacturing a printed wiring board with a built-in inductor and a printed wiring board with a built-in inductor that can reduce the resistance of the interlayer wiring even if the inductor wiring layer is thick The purpose is to do.

  The invention according to claim 1 is a first base material manufacturing step of manufacturing a first base material including a step of forming a first wiring layer on one surface of the first wiring forming layer, and one of the second wiring forming layers. Forming a second wiring layer on the surface, forming an adhesive layer on the other surface of the second wiring formation layer, and forming a via hole penetrating the second wiring formation layer and the adhesive layer. A second base material manufacturing step for manufacturing a second base material, comprising: a step; and a step of forming an interlayer wiring connected to the second wiring layer in the via hole; and the first base material and the second base material Are aligned, stacked, and pressed at a pressure lower than atmospheric pressure, thereby electrically connecting the interlayer wiring and the first wiring layer, and the first wiring layer, the second wiring layer, and the interlayer. A pre-built-in inductor comprising: a lamination process for forming an inductor by wiring It is a manufacturing method of preparative wiring board.

  2. The inductor according to claim 1, further comprising a step of forming the interlayer wiring by filling the via hole with a conductive paste containing metal particles by a vacuum printing method. It is a manufacturing method of a built-in printed wiring board.

  According to a third aspect of the present invention, in the second base material manufacturing step, the step of forming a through hole penetrating the via hole and the outside in the second wiring layer, and the through hole being formed, The method for manufacturing a printed wiring board with a built-in inductor according to claim 2, further comprising a step of filling a conductive paste from a via hole side.

  The invention according to claim 4 is characterized in that the laminating step includes a step of alloying the metal particles contained in the conductive paste of the interlayer wiring and the first wiring layer by heating. It is a manufacturing method of the printed wiring board with a built-in inductor according to any one of claims 2 to 3.

  The invention according to claim 5 includes a third base material manufacturing step of manufacturing one or a plurality of third base materials in which the third wiring layer is formed on the third wiring forming layer, and in the stacking step, 5. The inductor built-in print according to claim 1, wherein the base material, the second base material, and the one or more third base materials are laminated together. It is a manufacturing method of a wiring board.

  According to a sixth aspect of the present invention, there is provided a first base material having a first wiring layer formed on one surface of the first wiring forming layer, and a second wiring layer formed on one surface of the second wiring forming layer. An adhesive layer formed on the other surface of the second wiring formation layer and thicker than the first wiring layer; and a via hole penetrating the second wiring formation layer and the adhesive layer; A second base material having an interlayer wiring for electrically connecting the layer and the second wiring layer, and the first base material and the second base material are pressed at a pressure lower than atmospheric pressure. A printed wiring board with a built-in inductor, wherein the inductor is formed by stacking the first wiring layer, the second wiring layer, and the interlayer wiring.

  The invention according to claim 7 is the printed wiring board with a built-in inductor according to claim 6, wherein the first wiring forming layer, the second wiring forming layer, or the adhesive layer includes a magnetic material.

  According to the present invention, since the first base material and the second base material are laminated at a pressure lower than the atmospheric pressure, it is possible to suppress the formation of voids between the interlayer wiring and the wiring layer. Thereby, the resistance of the interlayer wiring can be reduced.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to a toroidal type printed wiring board with an inductor applied to a power supply circuit or the like will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a printed wiring board with a built-in inductor according to the first embodiment. In the following description, the vertical direction indicated by the arrows in FIG.

  As shown in FIG. 1, the inductor built-in printed wiring board 1 according to the first embodiment includes a first multilayer substrate 2, a second multilayer substrate 3, an inductor lower layer 4, and an inductor. And an upper layer base material 5. The printed wiring board 1 with a built-in inductor has a toroidal inductor 6 formed over the lower layer base material 4 for an inductor and the upper layer base material 5 for an inductor. In addition, the base material 2 for 1st multilayer substrates and the base material 3 for 2nd multilayer substrates are equivalent to the 3rd base material as described in a claim. The inductor lower layer base material 4 corresponds to the first base material recited in the claims. The inductor upper layer base material 5 corresponds to the second base material described in the claims.

  The first multilayer substrate 2 includes an insulating layer 11 and a copper wiring layer 12. The insulating layer 11 corresponds to the third wiring formation layer described in the claims. The copper wiring layer 12 corresponds to the third wiring layer recited in the claims.

  The insulating layer 11 is made of glass epoxy obtained by impregnating a glass cloth with an epoxy resin. The insulating layer 11 has a thickness of about 25 μm.

  The copper wiring layer 12 is formed on the upper surface of the insulating layer 11. The copper wiring layer 12 is patterned into a desired shape. The copper wiring layer 12 has a thickness of about 5 μm.

  The second multilayer substrate 3 includes an insulating layer 21, a copper wiring layer 22, an adhesive layer 23, and an interlayer wiring 24. In the insulating layer 21 and the adhesive layer 23, a via hole 25 penetrating both layers is formed. The insulating layer 21 corresponds to the third wiring formation layer described in the claims. The copper wiring layer 22 corresponds to the third wiring layer recited in the claims.

  The insulating layer 21 is made of glass epoxy obtained by impregnating a glass cloth with an epoxy resin. The insulating layer 21 has a thickness of about 25 μm.

  The copper wiring layer 22 is formed on the upper surface of the insulating layer 21. The copper wiring layer 22 is patterned into a desired shape. The copper wiring layer 22 has a thickness of about 5 μm.

  The adhesive layer 23 is formed on the lower surface of the insulating layer 21. The adhesive layer 23 is adhered to the insulating layer 11 while covering the copper wiring layer 12. The adhesive layer 23 is made of an adhesive mainly composed of a thermosetting epoxy.

  The interlayer wiring 24 is made of a conductive paste filled in the via hole 25. The conductive paste includes nickel (Ni) that is metal particles having low electrical resistance, tin (Sn) that is low-melting-point metal particles, and a binder mainly composed of an epoxy resin. The interlayer wiring 24 electrically connects the copper wiring layer 22 of the second multilayer substrate base material 3 and the copper wiring layer 12 of the first multilayer substrate base material 2.

  The inductor lower layer base material 4 includes an insulating layer 31, a copper wiring layer 32, an adhesive layer 33, and an interlayer wiring 34. In the insulating layer 31 and the adhesive layer 33, a via hole 35 penetrating both the layers 31 and 33 is formed. The insulating layer 31 corresponds to the first wiring formation layer described in the claims. The copper wiring layer 32 corresponds to the first wiring layer recited in the claims.

  The insulating layer 31 is made of glass epoxy obtained by impregnating a glass cloth with an epoxy resin. The insulating layer 31 includes a magnetic material. The insulating layer 31 has a thickness of about 25 μm.

  The copper wiring layer 32 is formed on the upper surface of the insulating layer 31. The copper wiring layer 32 has a thickness of about 100 μm. That is, the copper wiring layer 32 is formed thicker than the copper wiring layers 12 and 22 in order to reduce the resistance of the inductor 6. The copper wiring layer 32 is patterned into a desired shape. The copper wiring layer 32 includes an inductor lower layer wiring layer 32 a that constitutes a part of the inductor 6. L / S (line and space) of the inductor lower wiring layer 32a is 40 μm / 20 μm. The lower part of the copper wiring layer 32 includes a seed layer 32b. The seed layer 32b is made of a single metal or alloy thin film selected from chromium, nickel, copper, titanium, tungsten and the like. The metal thin film constituting the seed layer 32b may be one layer, but preferably two or more layers.

  The adhesive layer 33 is formed on the lower surface of the insulating layer 31. The adhesive layer 33 is bonded to the insulating layer 21 while covering the copper wiring layer 22. The adhesive layer 33 is made of an adhesive mainly composed of a thermosetting epoxy.

  The interlayer wiring 34 is made of a conductive paste filled in the via hole 35. The conductive paste includes nickel (Ni) that is metal particles having low electrical resistance, tin (Sn) that is low-melting-point metal particles, and a binder mainly composed of an epoxy resin. The interlayer wiring 34 electrically connects the copper wiring layer 32 of the lower layer base material 4 for inductor and the copper wiring layer 22 of the base material 3 for second multilayer substrate.

  The inductor upper layer base material 5 includes a magnetic layer 41, a copper wiring layer 42, an adhesive layer 43, and an interlayer wiring 44. In the magnetic layer 41 and the adhesive layer 43, a via hole 45 penetrating both layers 41 and 43 is formed. The magnetic layer 41 corresponds to the second wiring formation layer described in the claims. The copper wiring layer 42 corresponds to the second wiring layer recited in the claims. The adhesive layer 43 corresponds to the adhesive layer recited in the claims. The interlayer wiring 44 corresponds to the interlayer wiring described in the claims. The via hole 45 corresponds to the via hole recited in the claims.

  The magnetic layer 41 is made of a thin plate containing NiZn ferrite, which is a magnetic material.

  The copper wiring layer 42 is formed on one surface (hereinafter referred to as the upper surface) of the magnetic layer 41. The copper wiring layer 42 has a thickness of about 100 μm. The copper wiring layer 42 is patterned into a desired shape. The copper wiring layer 42 includes an inductor upper layer wiring layer 42 a that constitutes a part of the inductor 6. The lower part of the copper wiring layer 42 includes a seed layer 42b. The seed layer 42b is made of a simple metal or alloy thin film selected from chromium, nickel, copper, titanium, tungsten and the like. In the copper wiring layer 42, a through hole 42c penetrating from the outside to the via hole 45 is formed.

  The adhesive layer 43 is formed on the other surface (hereinafter, the lower surface) of the magnetic layer 41. The adhesive layer 43 is bonded to the insulating layer 31 while covering the copper wiring layer 32. The adhesive layer 43 is made of an adhesive mainly composed of a thermosetting epoxy containing a magnetic material.

  The interlayer wiring 44 is made of a conductive paste embedded in the via hole 45. The interlayer wiring 44 electrically connects the copper wiring layer 42 of the inductor upper layer base material 5 and the copper wiring layer 32 of the inductor lower layer base material 4. Here, a part of the interlayer wiring 44 electrically connects the inductor upper layer wiring layer 42a of the copper wiring layer 42 and the inductor lower layer wiring layer 32a of the copper wiring layer 32 for each turn. The toroidal inductor 6 is formed by the inductor lower wiring layer 32 a, the inductor upper layer wiring layer 42 a, and the interlayer wiring 44.

  Next, with reference to drawings, the manufacturing method of the printed wiring board 1 with a built-in inductor by 1st Embodiment mentioned above is demonstrated. 2 to 3 are diagrams for explaining a manufacturing process of the first base material for a multilayer substrate. 4-7 is a figure for demonstrating the manufacturing process of the base material for 2nd multilayer substrates. 8-13 is a figure for demonstrating the manufacturing process of the lower layer base material for inductors. 14-19 is a figure for demonstrating the manufacturing process of the upper-layer base material for inductors. FIG. 20 is a diagram for explaining a laminating process for laminating a base material.

  Initially, the process of producing the base material 2 for 1st multilayer substrates is demonstrated.

  First, as shown in FIG. 2, a single-sided copper-clad laminate (hereinafter referred to as single-sided CCL) 61 in which a copper foil 12A is bonded to an insulating layer 11 is prepared. A resist film 62 is formed on the copper foil 12A of the single-sided CCL 61 by a photolithography technique.

  Next, as shown in FIG. 3, the copper foil 12 </ b> A is patterned to form the copper wiring layer 12. Thereafter, the resist film 62 is removed. Thereby, the base material 2 for 1st multilayer substrates is completed.

  Next, the process for producing the second multilayer substrate 3 will be described.

  First, as shown in FIG. 4, a patterned copper wiring layer 22 is formed on the insulating layer 21 by the same manufacturing process as that of the first multilayer substrate 2 using the single-sided CCL.

  Next, as shown in FIG. 5, the adhesive layer 23 is temporarily attached to the lower surface of the insulating layer 21 by heating at a temperature of 80 ° C. to 150 ° C. for 5 seconds to 60 seconds.

  Next, as shown in FIG. 6, via holes 25 are formed at predetermined positions of the insulating layer 21 and the adhesive layer 23 by laser processing. For laser processing, a laser such as a UV-YAG laser or an excimer laser can be used. Thereafter, smear in the via hole 25 is removed by plasma treatment.

  Next, as shown in FIG. 7, an interlayer wiring 24 is formed by filling the inside of the via hole 25 with a conductive paste by a vacuum printing method. Accordingly, the second multilayer substrate 3 is completed in which the generation of voids can be suppressed at the interface between the via hole 25 and the copper wiring layer 22 and the resistance of the interlayer wiring 24 is reduced.

  Next, the process for producing the inductor lower layer base material 4 will be described.

  First, as shown in FIG. 8, an insulating layer 31 is prepared in which a seed layer 32b having a thickness of 0.1 μm to 1 μm is formed on the entire top surface. A plating resist film 64 is formed on the seed layer 32b by photolithography.

  Next, as shown in FIG. 9, copper having a thickness of about 100 μm is plated on the seed layer 32b. As a result, the copper wiring layer 32 including the inductor lower layer wiring layer 32 a constituting a part of the inductor 6 is formed on the upper surface of the insulating layer 31.

  Next, as shown in FIG. 10, the plating resist film 64 is peeled off. Thereafter, the exposed seed layer 32b is etched.

  Next, as shown in FIG. 11, the adhesive layer 33 is temporarily attached to the lower surface of the insulating layer 31 by heating at a temperature of 80 ° C. to 150 ° C. for 5 seconds to 60 seconds.

  Next, as shown in FIG. 12, a via hole 35 that penetrates both layers 31 and 33 and reaches the copper wiring layer 32 is formed at a predetermined position of the insulating layer 31 and the adhesive layer 33 by laser processing. Thereafter, smear in the via hole 35 is removed by plasma treatment.

  Next, as shown in FIG. 13, an interlayer wiring 34 is formed by filling the inside of the via hole 35 with a conductive paste by a vacuum printing method. Thereby, the lower layer base material 4 for an inductor in which the generation of voids can be suppressed at the interface between the via hole 35 and the copper wiring layer 32 and the resistance of the interlayer wiring 34 is reduced is completed.

  Next, a process for producing the inductor upper layer base material 5 will be described.

  First, as shown in FIG. 14, a thin magnetic layer 41 is prepared. Next, the seed layer 42 b is formed on the entire top surface of the magnetic layer 41. Thereafter, a plating resist film 65 is formed by photolithography.

  Next, as shown in FIG. 15, copper having a thickness of about 100 μm is plated on the seed layer 42b. As a result, the copper wiring layer 42 including the inductor upper wiring layer 42 a constituting a part of the inductor 6 is formed on the upper surface of the magnetic layer 41.

  Next, as shown in FIG. 16, the plating resist film 65 and the seed layer 42b are removed. Thereafter, the adhesive layer 43 is temporarily attached to the lower surface of the magnetic layer 41 by heating at a temperature of 80 to 150 ° C. for 5 to 60 seconds. The adhesive layer 43 has a thickness of about 120 μm, which is thicker than the copper wiring layer 32. As a result, the copper wiring layer 32 can be sufficiently covered with the adhesive layer 43 in the subsequent lamination step. The adhesive layer 43 is made of a thermosetting epoxy resin adhesive containing a magnetic material.

  Next, as shown in FIG. 17, a via hole 45 that penetrates both layers 41, 43 and reaches the copper wiring layer 42 is formed at a predetermined position of the magnetic layer 41 and the adhesive layer 43 by laser processing.

  Next, as shown in FIG. 18, a through hole 42c that penetrates the via hole 45 and the outside is formed in the copper wiring layer 42 by laser processing. Thereafter, smear in the via hole 45 is removed by plasma treatment.

  Next, as shown in FIG. 19, a conductive paste containing metal particles is filled into the via hole 45 by vacuum printing. Generation of voids at the interface between the via hole 45 and the copper wiring layer 42 can be suppressed, and the resistance of the interlayer wiring 44 can be reduced. The conductive paste is filled from the via hole 45 side. As a result, an interlayer wiring 44 connected to the copper wiring layer 42 is formed in the via hole 45. Here, since the through hole 42c is formed in the copper wiring layer 42, when the conductive paste is filled, the air escapes through the through hole 42c. For this reason, it is possible to reliably fill the via hole 45 with the conductive paste. As a result, the inductor upper layer base material 5 is completed.

  Next, as shown in FIG. 20, the base materials 2 to 5 are aligned and stacked at positions where they can be electrically connected to each other by image processing. Thereafter, the base materials 2 to 5 are heated to 150 ° C. to 250 ° C., and the atmospheric pressure around the base materials 2 to 5 is set to 1 kPa or less, which is lower than the atmospheric pressure. In this state, the base materials 2 to 5 are pressed at a pressure of 1 MPa to 5 MPa by a vacuum press machine or a cure press machine. By continuing this state for 30 minutes to 2 hours, the substrates 2 to 5 are laminated together. As a result, the tin particles of the conductive paste and the copper wiring layers 12, 22, 32 are alloyed, and the interlayer wirings 24, 34, 44 and the copper wiring layers 12, 22, 32 are electrically connected. The By alloying, the upper and lower circuits are connected better both electrically and physically than the paste where metal fillers come into contact with each other, and the adhesive layer enters the interface between the copper wiring layer and the interlayer wiring. Thus, an increase in electrical resistance can be prevented. Furthermore, it leads to improvement in heat and humidity resistance. Further, the copper wiring layers 12, 22 and 32 are covered with the adhesive layers 23, 33 and 43.

  As a result, the printed wiring board 1 with a built-in inductor shown in FIG. 1 is completed.

  As described above, in the printed wiring board 1 with a built-in inductor according to the first embodiment, the substrates 2 to 5 are stacked together by pressing them in an atmospheric pressure lower than the atmospheric pressure. As a result, the generation of voids between the interlayer wiring 44 and the copper wiring layer 32 can be suppressed. As a result, even if the copper wiring layer 32 including the inductor lower wiring layer 32a is thickened, the resistance of the interlayer wiring 44 can be reduced while improving the yield of interlayer conduction, and the long-term reliability can be improved. it can.

  Further, the inductor built-in printed wiring board 1 is constituted by a conductive paste in which an interlayer wiring 44 that connects the copper wiring layer 32 and the copper wiring layer 42 is filled in the via hole 45. For this reason, since the resistivity of the interlayer wiring 44 can be reduced, the diameter of the via hole 45 in which the interlayer wiring 44 is formed can be reduced. As a result, since the wiring density of the inductor 6 can be increased, the number of turns can be increased even with the same wiring length. Therefore, a desired inductance value can be obtained without increasing the DC resistance value of the inductor 6.

  Further, in the printed wiring board 1 with a built-in inductor, a through hole 42c is formed in the copper wiring layer 42 so as to penetrate the via hole 45 and the outside. Thereby, in the step of forming the interlayer wiring 44, the via hole 45 can be easily filled with the conductive paste. As a result, the generation of voids in the interlayer wiring 44 can be suppressed, and the resistance of the interlayer wiring 44 can be reduced. This effect is particularly effective when the aspect ratio of the interlayer wiring 44 is increased. Further, this effect is difficult to achieve because the same through hole cannot be formed by the build-up method in which the layers are sequentially laminated.

  Further, in the printed wiring board 1 with a built-in inductor, since the insulating layer 31, the magnetic layer 41, and the adhesive layer 43 contain a magnetic material, the inductance value can be improved.

(Second Embodiment)
Next, a second embodiment in which the first embodiment described above is partially changed will be described. FIG. 21 is a cross-sectional view of an inductor-embedded printed wiring board according to the second embodiment. FIG. 22 is a plan view of inductor wiring according to the second embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIGS. 21 and 22, the printed wiring board 1 </ b> A with a built-in inductor according to the second embodiment has a spiral type inductor 76.

  The inductor built-in printed wiring board 1 </ b> A includes a first multilayer substrate 2, a second multilayer substrate 3, an inductor 74, and an external wiring substrate 75.

  The inductor substrate 74 includes an inductor formation layer 81, a copper wiring layer 82, an adhesive layer 83, and an interlayer wiring 84. A via hole 85 is formed in the inductor formation layer 81 and the adhesive layer 83.

  The inductor forming layer 81 is made of glass epoxy obtained by impregnating a glass cloth with an epoxy resin.

  The copper wiring layer 82 is formed on the upper surface of the inductor forming layer 81. The copper wiring layer 82 has a thickness of about 100 μm. The copper wiring layer 82 is patterned into a desired shape. The copper wiring layer 82 includes an inductor wiring layer 82a. The inductor wiring layer 82 a constitutes a spiral type inductor 76. A lower portion of the copper wiring layer 82 includes a seed layer 82b. The seed layer 82b is made of a simple metal or alloy thin film selected from chromium, nickel, copper, titanium, tungsten and the like.

  The adhesive layer 83 is formed on the lower surface of the inductor forming layer 81. The adhesive layer 83 is made of an adhesive mainly composed of a thermosetting epoxy.

  The interlayer wiring 84 is made of a conductive paste filled in the via hole 85. The interlayer wiring 84 electrically connects the copper wiring layer 82 of the inductor base material 74 and the copper wiring layer 22 of the second multilayer substrate base material 3.

  The external wiring substrate 75 includes a wiring forming layer 91, a copper wiring layer 92, an adhesive layer 93, and an interlayer wiring 94.

  The wiring formation layer 91 is made of glass epoxy obtained by impregnating a glass cloth with an epoxy resin.

  The copper wiring layer 92 is formed on the upper surface of the wiring forming layer 91. The copper wiring layer 92 is connected to an external power supply or circuit.

  The adhesive layer 93 is formed on the lower surface of the wiring formation layer 91. The adhesive layer 93 is made of an adhesive mainly composed of a thermosetting epoxy.

  The interlayer wiring 94 is made of a conductive paste filled in the via hole 95. The interlayer wiring 94 electrically connects the copper wiring layer 92 of the external wiring base material 75 and the copper wiring layer 82 of the inductor base material 74.

  A method of manufacturing the printed wiring board 1A with a built-in inductor according to the second embodiment will be described.

  First, the first multi-layer substrate base material 2, the second multi-layer substrate base material 3, the inductor base material 74, and the external wiring base material 75 are separated by the same process as in the first embodiment. Make it.

  Next, the first multilayer substrate base material 2, the second multilayer substrate base material 3, the inductor base material 74, and the external wiring base material 75 are stacked in a pressure lower than the atmospheric pressure.

  Thereby, the printed wiring board 1A with a built-in inductor shown in FIG. 21 is completed.

  As mentioned above, although this invention was demonstrated in detail using embodiment, this invention is not limited to embodiment described in this specification. The scope of the present invention is determined by the description of the scope of claims and the scope equivalent to the description of the scope of claims. Hereinafter, modified embodiments in which the above-described embodiment is partially modified will be described.

  The material, numerical values such as thickness and width, shape, and the like of each component can be changed as appropriate.

  As the insulating layer, a glass cloth impregnated with a resin mainly composed of a polyimide resin or a polyester resin may be applied.

  The material constituting the wiring layer is not limited to copper, but a metal having a low resistivity is preferable.

  The adhesive layer may be composed of an adhesive mainly composed of thermoplastic polyimide.

  The metal contained in the conductive paste constituting the interlayer wiring can be appropriately changed. For example, at least one type of metal particles selected from silver (Ag) and copper (Cu) may be applied to the metal particles with low electrical resistance. The low melting point metal particles may be at least one kind of low melting point metal particles selected from bismuth (Bi), indium (In), lead (Pb), and zinc (Zn). Here, the low melting point metal particles are preferably tin that can be alloyed with the copper wiring layer. As a result, compared to the conductive paste that conducts when the metal fillers are in contact with each other, the circuit between the layers is connected better both electrically and physically, and the adhesive layer is formed of the conductive paste and the copper wiring. An increase in electrical resistance can be suppressed by entering the interface with the layer.

  Further, when the interlayer wirings 24 and 34 are formed, through holes may be provided in the same manner as the interlayer wiring 44.

  The magnetic layer is not limited to a thin plate made of NiZn ferrite, and may be composed of an insulating resin sheet in which a magnetic material having a high resistivity is dispersed.

  The magnetic body contained in the insulating layer, the adhesive layer, and the magnetic layer can be omitted as appropriate.

  Although the thickness of the copper wiring which comprises an inductor can be changed suitably, 100 micrometers or more are preferable. Thereby, the direct current resistance of the inductor can be reduced and heat generation can be suppressed.

  In the embodiment described above, the printed wiring board with a built-in inductor in which four layers of base materials are laminated has been described as an example. However, the printed wiring board with a built-in inductor in which the base materials of two layers, three layers, and five layers or more are laminated. The invention may be applied.

It is sectional drawing of the printed wiring board with a built-in inductor by 1st Embodiment. It is a figure for demonstrating the manufacturing process of the base material for 1st multilayer substrates. It is a figure for demonstrating the manufacturing process of the base material for 1st multilayer substrates. It is a figure for demonstrating the manufacturing process of the base material for 2nd multilayer substrates. It is a figure for demonstrating the manufacturing process of the base material for 2nd multilayer substrates. It is a figure for demonstrating the manufacturing process of the base material for 2nd multilayer substrates. It is a figure for demonstrating the manufacturing process of the base material for 2nd multilayer substrates. It is a figure for demonstrating the manufacturing process of the lower layer base material for inductors. It is a figure for demonstrating the manufacturing process of the lower layer base material for inductors. It is a figure for demonstrating the manufacturing process of the lower layer base material for inductors. It is a figure for demonstrating the manufacturing process of the lower layer base material for inductors. It is a figure for demonstrating the manufacturing process of the lower layer base material for inductors. It is a figure for demonstrating the manufacturing process of the lower layer base material for inductors. It is a figure for demonstrating the manufacturing process of the upper layer base material for inductors. It is a figure for demonstrating the manufacturing process of the upper layer base material for inductors. It is a figure for demonstrating the manufacturing process of the upper layer base material for inductors. It is a figure for demonstrating the manufacturing process of the upper layer base material for inductors. It is a figure for demonstrating the manufacturing process of the upper layer base material for inductors. It is a figure for demonstrating the manufacturing process of the upper layer base material for inductors. It is a figure for demonstrating the lamination process which laminates | stacks a base material. It is sectional drawing of the printed wiring board with a built-in inductor by 2nd Embodiment. It is a top view of the inductor by a 2nd embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A Inductor built-in printed wiring board 2 1st multilayer substrate base material 3 2nd multilayer substrate base material 4 Inductor lower layer base material 5 Inductor upper layer base material 6 Inductors 11, 21, 31 Insulating layers 12, 22, 32 , 42 Copper wiring layer 12A Copper foils 23, 33, 43 Adhesive layers 24, 34, 44 Interlayer wiring 25, 35, 45 Via hole 32a Inductor lower wiring layer 32b, 42b Seed layer 41 Magnetic layer 42a Inductor upper wiring layer 42c Through hole 62 Resist film 64 Plating resist film 65 Plating resist film 74 Inductor base material 75 External wiring base material 76 Inductor 81 Inductor forming layers 82 and 92 Copper wiring layer 82a Inductor wiring layer 82b Seed layers 83 and 93 Adhesive layers 84 and 94 Interlayer wiring 85, 95 Via hole 91 Wiring formation layer

Claims (7)

A first base material preparation step of preparing a first base material having a step of forming a first wiring layer on one surface of the first wiring formation layer;
A step of forming a second wiring layer on one surface of the second wiring formation layer, a step of forming an adhesive layer on the other surface of the second wiring formation layer, the second wiring formation layer and the adhesive layer, A second base material manufacturing step of manufacturing a second base material, including a step of forming a via hole penetrating through the substrate, and a step of forming an interlayer wiring connected to the second wiring layer in the via hole;
While aligning and laminating the first base material and the second base material and pressing in an atmospheric pressure lower than atmospheric pressure, while electrically connecting the interlayer wiring and the first wiring layer, A method of manufacturing a printed wiring board with a built-in inductor, comprising: a laminating step of forming an inductor with a first wiring layer, a second wiring layer, and an interlayer wiring.   2. The method of manufacturing a printed wiring board with a built-in inductor according to claim 1, further comprising a step of forming the interlayer wiring by filling the via hole with a conductive paste containing metal particles by a vacuum printing method. The second base material production step includes
Forming a through hole penetrating the via hole and the outside in the second wiring layer;
The method for manufacturing a printed wiring board with a built-in inductor according to claim 2, further comprising a step of filling a conductive paste from the via hole side in a state where the through hole is formed. The laminating step includes
4. The method according to claim 2, further comprising: a step of alloying the metal particles contained in the conductive paste of the interlayer wiring and the first wiring layer by heating. 5. Manufacturing method for printed wiring boards with built-in inductors. A third base material preparation step of preparing one or a plurality of third base materials in which the third wiring layer is formed on the third wiring formation layer;
The said 1st base material, a said 2nd base material, and the said 1 or several 3rd base material are laminated | stacked collectively in the said lamination process, The any one of Claims 1-4 characterized by the above-mentioned. 2. A method for manufacturing a printed wiring board with a built-in inductor according to item 1. A first substrate having a first wiring layer formed on one surface of the first wiring forming layer;
A second wiring layer formed on one surface of the second wiring formation layer; an adhesive layer formed on the other surface of the second wiring formation layer and thicker than the first wiring layer; and the second wiring formation layer And a second base material embedded in a via hole that penetrates the adhesive layer and having an interlayer wiring that electrically connects the first wiring layer and the second wiring layer,
The first base material and the second base material are laminated by pressing at a pressure lower than atmospheric pressure, and an inductor is formed by a first wiring layer, a second wiring layer, and an interlayer wiring. Built-in printed wiring board.   The printed wiring board with a built-in inductor according to claim 6, wherein the first wiring forming layer, the second wiring forming layer, or the adhesive layer includes a magnetic material.