Method for manufacturing a component-embedded substrate, and component-embedded substrate

Abstract

This invention provides a simplified manufacturing process for component-embedded circuit boards. [Solution] The method for manufacturing a component-embedded substrate comprises the steps of: providing an intermediate member 2 comprising an electronic component 10 having a first electrode 11 on a first surface 13 and a first conductive layer 20 provided on the first surface 13 of the electronic component 10 so as to cover the first electrode 11; and forming a first insulating resin layer 40 on the first surface 3 of the intermediate member 2. The first conductive layer 20 has a first cured adhesive layer 23 consisting of a cured adhesive layer 22 containing conductive particles 21 and a cured adhesive composition, and a first metal foil layer 24 disposed on the first cured adhesive layer 23 on the side opposite to the electronic component 10. The conductive particles 21 of the first cured adhesive layer 23 electrically connect the first electrode 11 of the electronic component 10 and the first metal foil layer 24.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a component-embedded substrate and a component-embedded substrate.

Background Art

[0002] Patent Document 1 discloses a method for manufacturing a printed wiring board incorporating electronic components such as IC chips.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional method for manufacturing a component-embedded substrate, as shown in FIGS. 5(a) and 5(b), insulating resin layers 102 and 103 are formed on both sides in the stacking direction of an electronic component 101 provided with electrodes 101a. Thereafter, as shown in FIGS. 5(c) and 5(d), via electrodes 104 and 105 reaching each electrode 101a of the electronic component 101 are formed in each of the insulating resin layers 102 and 103 by performing laser drilling, formation of a plating layer, electrode formation by etching, and the like. Then, as shown in FIGS. 6(a) to 6(c), formation of further insulating resin layers 106 and 107, formation of via electrodes 108 by laser drilling and formation of a plating layer, electrode formation by etching, and the like are repeated to form a component-embedded substrate 110. However, in such a method for manufacturing a component-embedded substrate, many processes are performed to form one conductive layer (via electrode), and these processes need to be repeated to form a plurality of conductive layers, resulting in a very complicated manufacturing process.

[0005] Therefore, an object of the present disclosure is to provide a method for manufacturing a component-embedded substrate with a simplified manufacturing process and a component-embedded substrate. [Means for solving the problem]

[0006] This disclosure relates, in one aspect, to a method for manufacturing a component-embedded substrate. This method for manufacturing a component-embedded substrate comprises (a) providing an intermediate member comprising an electronic component having a first electrode on its first surface and a first conductive layer provided on the first surface of the electronic component so as to cover the first electrode, and (b) forming a first insulating resin layer on the first surface of the intermediate member. The first conductive layer comprises a first cured adhesive layer comprising a cured adhesive layer containing conductive particles and a cured adhesive composition, and a first metal foil layer disposed on the first cured adhesive layer on the side opposite to the electronic component. The conductive particles of the first cured adhesive layer electrically connect the first electrode of the electronic component and the first metal foil layer.

[0007] In this method for manufacturing a component-embedded substrate, the first conductive layer of the intermediate member provided in step (a) is composed of a first cured adhesive layer comprising conductive particles and a cured adhesive composition, and a first metal foil layer, wherein the conductive particles of the first cured adhesive layer electrically connect the first electrode of the electronic component and the first metal foil layer. In this case, the intermediate member containing the electronic component can be simplified, thus simplifying the method for manufacturing the component-embedded substrate.

[0008] In the above-described method for manufacturing a component-embedded substrate, the intermediate member further comprises a second conductive layer provided on a second surface opposite to the first surface of the electronic component, and a second electrode may be provided on the second surface opposite to the first surface of the electronic component. The second conductive layer comprises a second cured adhesive layer consisting of conductive particles and a cured adhesive composition, and a second metal foil layer disposed on the second cured adhesive layer on the surface opposite to the electronic component. The conductive particles of the second cured adhesive layer electrically connect the second electrode of the electronic component and the second metal foil layer. In this case, since simplified conductive layers are provided on both sides of the electronic component, the method for manufacturing a component-embedded substrate can be made simpler.

[0009] In the above-described method for manufacturing a component-embedded substrate, step (a) of providing an intermediate member may include steps of: preparing an electronic component (a1); preparing a first adhesive film (a2); attaching the first adhesive film to the first surface of the electronic component so as to cover the first electrode (a3); and heat-pressing the first adhesive film to the electronic component (a5). The first adhesive film comprises a first adhesive layer consisting of an adhesive layer in which conductive particles and an adhesive composition are dispersed in the adhesive composition, and a first metal foil layer disposed on the first adhesive layer on the side opposite to the electronic component. In step (a5) of heat-pressing, the first adhesive film is heat-pressed so that the conductive particles of the first adhesive film electrically connect the first electrode of the electronic component to the first metal foil layer, and the adhesive layer of the first adhesive film is cured to form a first cured adhesive layer. In this case, since the conductive layer is formed using an adhesive film containing conductive particles dispersed in the adhesive composition, a conductive layer connecting electrodes that are far apart in the stacking direction can be easily formed without performing complicated processes such as laser drilling, plating layer formation, and electrode formation by etching. As a result, the manufacturing method for component-embedded substrates can be made simpler. Note that the order in which steps (a1) to (a3) ​​and (a5) are performed is not limited to the order described above, and the order can be changed as appropriate.

[0010] In the above-described method for manufacturing a component-embedded substrate, step (a) of providing an intermediate member may include steps of: preparing an electronic component (a1); preparing a first adhesive film and a second adhesive film (a2); attaching the first adhesive film to the first surface of the electronic component so as to cover the first electrode (a3); attaching the second adhesive film to the second surface of the electronic component so as to cover the second electrode (a4); and heating and pressing the first adhesive film and the second adhesive film to the electronic component (a5). The first adhesive film comprises a first adhesive layer consisting of an adhesive layer in which conductive particles are dispersed in the adhesive composition and conductive particles, and a first metal foil layer disposed on the first adhesive layer on the side opposite to the electronic component. The second adhesive film comprises a second adhesive layer consisting of an adhesive layer in which conductive particles are dispersed in the adhesive composition and conductive particles, and a second metal foil layer disposed on the second adhesive layer on the side opposite to the electronic component. Furthermore, the order of steps (a1) to (a5) described above is not limited to the order listed above, and the order can be changed as appropriate. For example, the order in which steps (a1) and (a2) are performed is not limited; step (a1) may be performed first, or conversely, step (a2) may be performed first, or even steps (a1) and (a2) may be performed simultaneously. Also, for example, the order in which steps (a3) ​​and (a4) are performed is not limited; step (a3) ​​may be performed first, or conversely, step (a4) may be performed first, or even steps (a3) ​​and (a4) may be performed simultaneously.

[0011] In the heat-pressing step (a5), the first adhesive film may be heat-pressed to electrically connect the first electrode of the electronic component to the first metal foil layer with the conductive particles of the first adhesive film, and the adhesive layer of the first adhesive film may be cured to form a first cured adhesive layer. Alternatively, the second adhesive film may be heat-pressed to electrically connect the second electrode of the electronic component to the second metal foil layer with the conductive particles of the second adhesive film, and the adhesive layer of the second adhesive film may be cured to form a second cured adhesive layer. In this case, since conductive layers on both sides of the electronic component are formed using an adhesive film containing conductive particles, each conductive layer connecting electrodes that are separated in the stacking direction can be easily formed without performing complicated processes such as laser drilling, plating layer formation, and electrode formation by etching on both sides of the electronic component. As a result, this manufacturing method can further simplify the manufacturing method of component-embedded substrates.

[0012] In the above-described method for manufacturing a component-embedded substrate, the ratio of the surface roughness Rz of at least one of the first and second metal foil layers, on the side that is bonded to the corresponding adhesive layer, to the average particle size of the conductive particles may be 0.05 to 3. In this case, compared to the case where the ratio of the surface roughness Rz of the adhesive layer to the average particle size of the conductive particles is greater than 3, the conductive particles can be more reliably flattened during heat bonding, thereby increasing the contact area between the conductive particles and the metal foil layer and the electrodes of the electronic components. As a result, the electrical conductivity between the metal foil layer, which becomes a wiring pattern or wiring after processing, and the electrodes of the electronic components can be made more stable with these conductive particles. This ratio can be expressed as surface roughness Rz / average particle size.

[0013] In the above-described method for manufacturing a component-embedded substrate, the surface roughness Rz of the side of at least one of the first and second metal foil layers that is bonded to the corresponding adhesive layer may be 20 μm or less. In this case, compared to the case where the surface roughness of the metal foil layer side on the adhesive layer side is rough, the conductive particles can be more reliably flattened during heat bonding, thereby increasing the contact area between the conductive particles and the metal foil layer and the electrodes of the electronic components. As a result, the electrical conductivity between the metal foil layer that becomes a wiring pattern or wiring after processing and the electrodes of the electronic components can be made more stable by these conductive particles.

[0014] In the above-described method for manufacturing a component-embedded substrate, step (a) of providing an intermediate member may further include step (a6) of etching at least one of the first metal foil layer and the second metal foil layer to form an outer electrode of the intermediate member.

[0015] The above-described method for manufacturing a component-embedded substrate may further include step (d) forming a via conductor on a first insulating resin layer formed on the first surface of an intermediate member, extending to a first metal foil layer or an outer electrode processed from the first metal foil layer.

[0016] In the above-described method for manufacturing a component-embedded substrate, the ratio of the surface roughness Rz of the corresponding side of the cured adhesive layer of at least one of the first and second metal foil layers to the average particle size of the conductive particles may be 0.05 to 3. In this case, compared to the case described above where the ratio of the surface roughness Rz of the cured adhesive layer to the average particle size of the conductive particles is greater than 3, the conductive particles can be more reliably flattened, increasing the contact area between the conductive particles and the metal foil layer and the electrodes of the electronic components. As a result, the electrical conductivity between the metal foil layer, which becomes a wiring pattern or wiring after processing, and the electrodes of the electronic components can be made more stable.

[0017] In the above-described method for manufacturing a component-embedded substrate, the surface roughness Rz of the corresponding side of the curing adhesive layer of at least one of the first and second metal foil layers may be 20 μm or less. In this case, compared to the case where the surface roughness of the metal foil layer side on the adhesive layer side is rough, conductive particles can be more reliably flattened, increasing the contact area between the conductive particles and the metal foil layer and the electrodes of the electronic components. As a result, electrical conductivity between the metal foil layer, which becomes a wiring pattern or wiring after processing, and the electrodes of the electronic components can be made stable. In this case, the surface roughness Rz of the corresponding side of the curing adhesive layer may be 0.5 μm or more and 5.0 μm or less, or 0.5 μm or more and 10 μm or less.

[0018] The above-described method for manufacturing a component-embedded substrate may further include step (c) of forming a second insulating resin layer on the second surface of the intermediate member opposite to the first surface. In this case, the first insulating resin layer is formed on the first surface of the intermediate member, and the second insulating resin layer is formed on the second surface on the opposite side, thereby suppressing warping caused by each insulating resin layer.

[0019] Furthermore, this disclosure relates, in another aspect, to a component-embedded substrate. This component-embedded substrate comprises an intermediate member having an electronic component having a first electrode on its first surface and a first conductive layer provided on the first surface of the electronic component so as to cover the first electrode, and a first insulating resin layer formed on the first surface of the intermediate member. The first conductive layer has a first cured adhesive layer consisting of a cured adhesive layer containing conductive particles and a cured adhesive composition, and a first metal foil layer disposed on the first cured adhesive layer on the side opposite to the electronic component. The conductive particles of the first cured adhesive layer electrically connect the first electrode of the electronic component and the first metal foil layer.

[0020] In the component-embedded substrate, the first conductive layer of the intermediate member is composed of a first cured adhesive layer including conductive particles and a cured adhesive composition and having a first metal foil layer, and the conductive particles of the first cured adhesive layer electrically connect the first electrode of the electronic component and the first metal foil layer. In this case, since the intermediate member including the electronic component is simplified, the structure of the component-embedded substrate can be made simple.

[0021] In the above component-embedded substrate, the intermediate member further includes a second conductive layer provided on a second surface opposite to the first surface of the electronic component, and a second electrode may be provided on the second surface opposite to the first surface of the electronic component. The second conductive layer includes a second cured adhesive layer composed of a cured adhesive composition including conductive particles and a second metal foil layer disposed on a surface of the second cured adhesive layer opposite to the electronic component. The conductive particles of the second cured adhesive layer electrically connect the second electrode of the electronic component and the second metal foil layer. In this case, since the intermediate member including the electronic component is further simplified, the structure of the component-embedded substrate can be made simpler. Also, since similar cured adhesive layers are provided on both surfaces of the electronic component, the balance in the stacking direction is improved, and even when thermal expansion or the like occurs in the component-embedded substrate, uneven expansion can be suppressed.

[0022] The above component-embedded substrate may further include a second insulating resin layer formed on a second surface opposite to the first surface of the intermediate member. In this case, a first insulating resin layer is formed on the first surface of the intermediate member, and a second insulating resin layer is formed on the opposite second surface, and warping or the like caused by each insulating resin layer can be suppressed.

Advantages of the Invention

[0023] According to the present disclosure, the manufacturing method of the component-embedded substrate can be made simpler.

Brief Description of the Drawings

[0024] [Figure 1] FIG. 1 is a cross-sectional view showing a component-embedded substrate according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view showing an adhesive film used when manufacturing the component-embedded substrate shown in FIG. 1. [Figure 3] (a) to (d) of FIG. 3 are cross-sectional views for sequentially explaining a method of manufacturing the component-embedded substrate shown in FIG. 1. [Figure 4] (a) to (c) of FIG. 4 are cross-sectional views for sequentially explaining a method of manufacturing the component-embedded substrate shown in FIG. 1, showing the steps following those in FIG. 3. [Figure 5] (a) to (d) of FIG. 5 are cross-sectional views for sequentially explaining a method of manufacturing a conventional component-embedded substrate. [Figure 6] (a) to (c) of FIG. 6 are cross-sectional views for sequentially explaining a method of manufacturing a conventional component-embedded substrate, showing the steps following those in FIG. 5.

Embodiments for Carrying Out the Invention

[0025] Hereinafter, a component-embedded substrate according to an embodiment of the present disclosure and a method of manufacturing the component-embedded substrate will be described with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and overlapping descriptions are omitted. Also, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the illustrated ratios.

[0026] FIG. 1 is a cross-sectional view showing a component-embedded substrate according to an embodiment of the present disclosure. As shown in FIG. 1, the component-embedded substrate 1 includes an intermediate member 2 including an electronic component 10, a first conductive layer 20, and a second conductive layer 30, a first insulating resin layer 40, and a second insulating resin layer 50. The electronic component 10 is, for example, an electronic component such as an IC chip, has a first surface 13 and an opposite second surface 14, a first electrode 11 is provided on the first surface 13, and a second electrode 12 is provided on the second surface 14 (see (a) of FIG. 3). The electronic component 1 can be other electronic components such as a capacitor, or may have a configuration in which a conductive layer and an insulating resin layer are provided only on one surface side (for example, the first surface 13).

[0027] The first conductive layer 20 is a layer that includes a conductive region provided on the first surface 13 of the electronic component 10 so as to cover the first electrode 11 on the first surface 13, and electrically connects one electrode in the lamination direction to the other electrode. The first conductive layer 20 has a first cured adhesive layer 23 consisting of conductive particles 21 and a cured adhesive layer 22 containing a cured adhesive composition, and a first metal foil layer 24 (internal electrode) arranged on the first cured adhesive layer 23 on the side opposite to the electronic component 10. The first metal foil layer 24 may be a metal foil layer before processing, or a metal foil layer after processing into an electrode pattern, etc. As described later, the first conductive layer 20 is formed by heating and pressing the first adhesive film 60 (see Figure 3(b)) so that the conductive particles 61a of the first adhesive film 60 electrically connect the first electrode 11 of the electronic component 10 to the first metal foil layer 24, and the adhesive layer 62 of the first adhesive film 60 is heat-cured (see Figure 3(c)). In other words, the adhesive layer portion of the first cured adhesive layer 23 is a cured product formed by the curing of a thermosetting adhesive composition. The conductive particles 21 are not particularly limited as long as they are conductive particles, and may be metal particles composed of metals such as Au, Ag, Ni, Cu, or solder, or conductive carbon particles composed of conductive carbon. The conductive particles 21 may also be coated conductive particles comprising a core containing non-conductive glass, ceramic, or plastic (such as polystyrene), and a coating layer containing the above-mentioned metal or conductive carbon that covers the core. Furthermore, the conductive particles 21 may also be insulating coated conductive particles comprising the metal particles, conductive carbon particles, or coated conductive particles and an insulating layer containing an insulating material such as resin that covers the surface of the particles.

[0028] The second conductive layer 30 is a layer that includes a conductive region provided on the second surface 14 of the electronic component 10 so as to cover the second electrode 12 on the second surface 14, and electrically connects one electrode in the lamination direction to the other electrode. The second conductive layer 30 has a second cured adhesive layer 33 consisting of conductive particles 31 and a cured adhesive layer 32 containing a cured adhesive composition, and a second metal foil layer 34 (internal electrode) arranged on the second cured adhesive layer 33 on the side opposite to the electronic component 10. The second metal foil layer 34 may be a metal foil layer before processing, or a metal foil layer after processing into an electrode pattern, etc. As described later, the second conductive layer 30 is formed by heating and pressing the second adhesive film 70 (see Figure 3(b)) so that the conductive particles 71a of the second adhesive film 70 electrically connect the second electrode 12 of the electronic component 10 to the second metal foil layer 34, and the adhesive layer 72 of the second adhesive film 70 is heat-cured (see Figure 3(c)). In other words, the adhesive layer portion of the second curing adhesive layer 33 is a cured product formed by the curing of a thermosetting adhesive composition. The conductive particles 31 are not particularly limited as long as they are conductive particles, and may be metal particles composed of metals such as Au, Ag, Ni, Cu, or solder, or conductive carbon particles composed of conductive carbon. The conductive particles 31 may also be coated conductive particles comprising a core containing non-conductive glass, ceramic, or plastic (such as polystyrene), and a coating layer containing the above-mentioned metal or conductive carbon that covers the core. Furthermore, the conductive particles 31 may also be insulating coated conductive particles comprising the metal particles, conductive carbon particles, or coated conductive particles and an insulating layer containing an insulating material such as resin that covers the surface of the particles.

[0029] The first insulating resin layer 40 is a layer formed on the first surface 3 of the intermediate member 2, and has an insulating layer 41, a via conductor 42, and an external electrode 43. The insulating layer 41 is composed of a resin such as epoxy and inorganic particles such as glass. The insulating layer 41 may also contain a reinforcing material such as glass cloth. The via conductor 42 is a conductive member for electrically connecting the first metal foil layer 24 (internal electrode) of the intermediate member 2 to the external electrode 43, and is composed of plating or the like that filled in through holes provided in the insulating layer 41. The external electrode 43 is electrically connected to the upper end of this via conductor 42.

[0030] The second insulating resin layer 50 is an insulating layer formed on the second surface 4 of the intermediate member 2. The second insulating resin layer 50 is composed of a resin such as epoxy and inorganic particles such as glass. The second insulating resin layer 50 may also contain reinforcing materials such as glass cloth. The second insulating resin layer 50 may have via conductors and external electrodes, similar to the first insulating resin layer 40.

[0031] Next, the manufacturing method of the component-embedded substrate described above will be explained with reference to Figures 2 to 4. Figure 2 is a cross-sectional view showing the adhesive film used when manufacturing the component-embedded substrate shown in Figure 1. Figures 3(a) to 3(d) are cross-sectional views illustrating the manufacturing method of the component-embedded substrate shown in Figure 1 in order. Figures 4(a) to 4(c) are cross-sectional views illustrating the manufacturing method of the component-embedded substrate shown in Figure 1 in order, and show the steps following those in Figure 3. The manufacturing method for a component-embedded substrate according to this embodiment comprises the steps of: (a) providing an intermediate member comprising an electronic component having a first electrode and a second electrode on its first and second surfaces, a first conductive layer provided on the first surface of the electronic component so as to cover the first electrode, and a second conductive layer provided on the second surface of the electronic component so as to cover the second electrode; (b) forming a first insulating resin layer on the first surface of the intermediate member; (c) forming a second insulating resin layer on the second surface of the intermediate member opposite to the first surface; and (d) forming a via conductor on the first insulating resin layer formed on the first surface of the intermediate member, extending to a first metal foil layer or an outer electrode processed from the first metal foil layer. A detailed explanation follows below. Note that the order of steps (a) to (d) is not limited to the order described above, and the order can be changed as appropriate. For example, the process may be carried out in the order (a), (b), (c), (d), or in the order (a), (c), (b), (d), or in the order (a), (b), (d), (c).

[0032] [Step of providing an intermediate member (a)] Step (a) of providing the intermediate member 2 includes the steps of: preparing the electronic component 10 (a1); preparing the first adhesive film (a2); attaching the first adhesive film to the first surface of the electronic component so as to cover the first electrode (a3); heating and pressing the first adhesive film against the electronic component (a4); and etching the first metal foil layer to form the outer electrode of the intermediate member (a5). Alternatively, the outer electrode may be formed on the second surface side of the intermediate member by the same method.

[0033] In the step of preparing the electronic component (a1), an electronic component 10 is prepared, as shown in Figure 3(a), in which a first electrode 11 and a second electrode 12 are provided on a first surface 13 and a second surface 14. The electronic component 10 is, for example, an IC chip. In addition, there may be multiple first electrodes 11 and second electrodes 12.

[0034] In step (a2) of preparing the adhesive film, as shown in Figure 2, a first adhesive film 60 is prepared having a first adhesive layer 63 consisting of an adhesive layer 62 in which a plurality of conductive particles 61 and an adhesive composition are dispersed in the adhesive composition, and a first metal foil layer 64 on the first adhesive layer 63. Similarly, a second adhesive film 70 is prepared having a second adhesive layer 73 consisting of an adhesive layer 72 in which a plurality of conductive particles 71 and an adhesive composition are dispersed in the adhesive composition, and a second metal foil layer 74 on the second adhesive layer 73, on the side opposite to the electronic component 10. Such first adhesive films 60 and second adhesive films 70 are wiring forming members. The adhesive compositions of adhesive layers 62 and 72 are adhesive compositions containing thermosetting insulating resins such as epoxy resin, phenolic resin, and acrylic resin, in which conductive particles 61 and 71 with a particle size of several μm are dispersed and blended.

[0035] The average particle size Dp of the conductive particles 61 and 71 may be 1 μm or more, 2 μm or more, or 5 μm or more, from the viewpoint of excellent dispersibility and conductivity. The average particle size Dp of the conductive particles may be 50 μm or less, 30 μm or less, or 20 μm or less, from the viewpoint of excellent dispersibility and conductivity. From the above viewpoint, the average particle size Dp of the conductive particles may be 1 to 50 μm, 5 to 30 μm, 5 to 20 μm, or 2 to 20 μm.

[0036] The maximum particle size of the conductive particles 61, 71 may be smaller than the minimum distance between electrodes in the wiring pattern (the shortest distance between adjacent electrodes). From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of the conductive particles 61, 71 may be 1 μm or more, 2 μm or more, or 5 μm or more. From the viewpoint of excellent dispersibility and conductivity, the maximum particle size of the conductive particles may be 50 μm or less, 30 μm or less, or 20 μm or less. From the above viewpoint, the maximum particle size of the conductive particles may be 1 to 50 μm, 2 to 30 μm, or 5 to 20 μm.

[0037] In this specification, the particle size of any 300 particles (pcs) is measured by observation using a scanning electron microscope (SEM). The average value of the obtained particle sizes is defined as the average particle size Dp, and the largest value obtained is defined as the maximum particle size. If the particle has protrusions or other non-spherical shapes, the particle size is defined as the diameter of the circle circumscribing the particle in the SEM image.

[0038] The first metal foil layer 64 and the second metal foil layer 74 are, for example, copper foil, aluminum foil, nickel foil, stainless steel, titanium, or platinum. The surface roughness Rz of the side 65 of the first metal foil layer 64 that is bonded to the first adhesive layer 63 may be 20 μm or less, or it may be 0.5 μm or more and 5.0 μm or less, or it may be 0.5 μm or more and 10 μm or less. Similarly, the surface roughness Rz of the side 75 of the second metal foil layer 74 that is bonded to the second adhesive layer 73 may be 20 μm or less, or it may be 0.5 μm or more and 5.0 μm or less, or it may be 0.5 μm or more and 10 μm or less.

[0039] Surface roughness Rz refers to the ten-point average roughness Rzjis measured according to the method specified in the JIS standard (JIS B 0601-2001), and is a value measured using a commercially available surface roughness shape measuring instrument. For example, it can be measured using a nanosearch microscope (Shimadzu Corporation's "SFT-3500").

[0040] Hereinafter, the relationship between the average particle size Dp of the conductive particles 61 and the surface roughness Rz of the surface 65 of the first metal foil layer 64, and the relationship between the average particle size Dp of the conductive particles 71 and the surface roughness Rz of the surface 75 of the second metal foil layer 74 will be explained. In this embodiment, the ratio of the surface roughness Rz of the surfaces 65 and 75 of the metal foil layers 64 and 74 to the average particle size Dp of the conductive particles 61 and 71, which is "surface roughness / average particle size", may be 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.5 or more, or 1 or more. Furthermore, the "surface roughness / average particle size" ratio, which is the ratio of the surface roughness Rz of the surfaces 65 and 75 of the metal foil layers 64 and 74 to the average particle size Dp of the conductive particles 61 and 71, may be 3 or less, 2 or less, 1.7 or less, or 1.5 or less. The "surface roughness / average particle size" ratio, which is the ratio of the surface roughness Rz of the surfaces 65 and 75 of the metal foil layers 64 and 74 to the average particle size Dp of the conductive particles 61 and 71, may be, for example, 0.05 or more and 3 or less, and more specifically, 0.06 or more and 2 or less. In this embodiment, the surface roughness Rz of the surfaces 65 and 75 of the metal foil layers 64 and 74 and the average particle size Dp of the conductive particles 61 and 71 may be controlled so that the "surface roughness / average particle size" ratio, which is the ratio of the surface roughness Rz of the surfaces 65 and 75 of the metal foil layers 64 and 74 to the average particle size Dp of the conductive particles 61 and 71, is in the range of 0.05 to 3.

[0041] Furthermore, it has been found that when the ratio of the surface roughness Rz of the metal foil layers 64,74 that are bonded to the adhesive layers 63,73, to the average particle size of the conductive particles 61,71 is between 0.05 and 3, the conductive particles 61,71 can be more reliably flattened, thereby increasing the contact area between the conductive particles 61,71 and the metal foil layers 64,74, compared to when this ratio is greater than 3. Therefore, by setting the ratio of surface roughness Rz to average particle size within the above range, electrical conductivity between the metal foil layers 64,74, which become wiring patterns or wiring after processing, and other wiring patterns or wiring to which the adhesive layers 63,73 are bonded can be stabilized.

[0042] In steps (a3) ​​and (a4) of attaching the adhesive film, as shown in Figure 3(b), the first adhesive film 60 is attached to the first surface 13 of the electronic component 10 so as to cover the first electrode 11 on the first surface 13. Similarly, the second adhesive film 70 is attached to the second surface 14 of the electronic component 10 so as to cover the second electrode 12 on the second surface 14. At this time, the first metal foil layer 64 and the second metal foil layer 74 are positioned on the opposite side from the electronic component 10.

[0043] In step (a5) of heat-pressing the adhesive films, as shown in Figure 3(c), the first adhesive film 60 and the second adhesive film 70 are heat-pressed and attached to the electronic component 10. By heat-pressing the first adhesive film 60, the conductive particles 61a of the first adhesive film 60 electrically connect the first electrode 11 on the first surface 13 of the electronic component 10 to the first metal foil layer 64, and the adhesive layer 62 of the first adhesive film 60 is cured to form the first cured adhesive layer 60a(20). Similarly, by heat-pressing the second adhesive film 70, the conductive particles 71a of the second adhesive film 70 electrically connect the second electrode 12 on the second surface 14 of the electronic component 10 to the second metal foil layer 74, and the adhesive layer 72 of the second adhesive film 70 is cured to form the second cured adhesive layer 70a(30). The heat-pressing of the first adhesive film 60 and the second adhesive film 70 may be performed simultaneously or sequentially. Furthermore, if the ratio of the surface roughness Rz of the sides 65 and 75 of the metal foil layers 64 and 74 that are bonded to the adhesive layers 63 and 73 to the average particle size of the conductive particles 61 and 71 is 0.05 to 3, or if the surface roughness Rz of each side 65 and 75 of the first metal foil layer 64 and the second metal foil layer 74 is 20 μm or less, then each conductive particle 61 and 71 can be more easily flattened, and the conductivity of the electronic component 10 can be stabilized.

[0044] Next, in the step (a6) of forming the outer electrodes of the intermediate member, as shown in Figure 3(d), the first metal foil layer 64 of the first curing adhesive layer 60a is etched to become a predetermined electrode 64a(24). Similarly, the second metal foil layer 74 of the second curing adhesive layer 70a is etched to become a predetermined electrode 74a(34). This forms via electrodes that connect to the electronic component 10 in the intermediate member 2. In step (a) above, since the conductive layer of the electronic component 10 is formed using an adhesive film containing conductive particles, each conductive layer connecting electrodes that are far apart in the stacking direction can be easily formed without having to perform complicated processes such as laser drilling, plating layer formation, and electrode formation by etching on the outside of the electronic component as in the conventional method. As a result, this manufacturing method simplifies the manufacturing method of the component-embedded substrate 1.

[0045] Once the step of providing the intermediate member (a) is completed, in the steps of forming the insulating resin layer (b) and (c), as shown in Figure 4(a), a first insulating resin layer 40 is formed on the first surface 3 of the intermediate member 2, and a second insulating resin layer 50 is formed on the second surface 4 opposite to the first surface 3 of the intermediate member 2. Then, holes 44 are formed at predetermined locations in the first insulating resin layer 40 using a laser or the like. The holes 44 are holes that extend from the outside of the first insulating resin layer 40 to the electrodes (first metal foil layer 24) of the intermediate member 2. Then, as shown in Figure 4(b), plating is filled into the holes 44 to form via conductors 42 and electrode layers 45. The electrode layers 45 are then further etched to become predetermined external electrodes 43 to obtain the component-embedded substrate 1 shown in Figure 4(c).

[0046] As described above, in the manufacturing method of the component-embedded substrate 1 according to this embodiment, the first conductive layer 20 of the intermediate member 2 provided in step (a) is composed of a first cured adhesive layer 23 consisting of conductive particles 21 (61a) and a cured adhesive layer 22 (62a) containing a cured adhesive composition, and a first metal foil layer 24, wherein the conductive particles 21 of the first cured adhesive layer 23 electrically connect the first electrode 11 of the electronic component 10 and the first metal foil layer 24. Similarly, the second conductive layer 30 of the intermediate member 2 is composed of a second cured adhesive layer 33 consisting of conductive particles 31 (71a) and a cured adhesive layer 32 (72a) containing a cured adhesive composition, and a second metal foil layer 34, wherein the conductive particles 31 of the second cured adhesive layer 33 electrically connect the second electrode 12 of the electronic component 10 and the second metal foil layer 34. Thus, in the manufacturing method according to this embodiment, the intermediate member 2 including the electronic component 10 can be made into a simplified structure, and therefore the manufacturing method of the component-embedded substrate 1 can be simplified compared to conventional methods.

[0047] Furthermore, in the manufacturing method of the component-embedded substrate according to this embodiment, the ratio of the surface roughness Rz of the side 65, 75 of at least one of the metal foil layers of the first metal foil layer 64 and the second metal foil layer 74 that is bonded to the adhesive layer to the average particle size of the conductive particles 61, 71 may be 0.05 to 3. Alternatively, the surface roughness Rz of the side of at least one of the metal foil layers of the first metal foil layer 64 and the second metal foil layer 74 that is bonded to the corresponding adhesive layers 63, 73 may be 20 μm or less. In this case, compared to the case where the ratio of surface roughness Rz to the average particle size is greater than 3, or where the surface roughness of the side of the metal foil layer on the adhesive layer side is rough, the conductive particles 61, 71 can be more reliably flattened during heat bonding, thereby increasing the contact area between the conductive particles 61a, 71a and the metal foil layer and the electrodes of the electronic component. In other words, if the ratio of surface roughness Rz to average particle size is greater than 3, or if the surface of the metal foil layer on the adhesive layer side is rough, conductive particles may get trapped in the rough surface shape, and when heat-pressed, the conductive particles may not be sufficiently crushed (for example, into a flat shape), which can lead to unstable conductivity. However, by setting the ratio of surface roughness Rz to average particle size to 0.05-3, or by setting the surface roughness Rz of the metal foil layer surface to 20 μm or less, it becomes possible to reliably crush the conductive particles during heat-pressing. As a result, the electrical conductivity between the metal foil layer that becomes the wiring pattern or wiring after processing and the electrodes of the electronic component can be made more stable by these conductive particles.

[0048] Furthermore, in the component-embedded substrate 1 according to this embodiment, the first conductive layer 20 of the intermediate member 2 is composed of a first cured adhesive layer 23 consisting of conductive particles 21 and a cured adhesive layer 22 containing a cured adhesive composition, and a first metal foil layer 24, with the conductive particles 21 of the first cured adhesive layer 23 electrically connecting the first electrode 11 of the electronic component 10 and the first metal foil layer 24. Similarly, the second conductive layer 30 of the intermediate member 2 is composed of a second cured adhesive layer 33 consisting of conductive particles 31 and a cured adhesive layer 32 containing a cured adhesive composition, and a second metal foil layer 34, with the conductive particles 31 of the second cured adhesive layer 33 electrically connecting the second electrode 12 of the electronic component 10 and the second metal foil layer 34. In this case, since the intermediate member 2 including the electronic component 10 is simplified by using an adhesive film, the structure of the component-embedded substrate 1 can be made simpler. Furthermore, since similar cured adhesive layers are provided on both sides of the electronic component 10, the balance in the stacking direction is improved, and even if thermal expansion occurs in the component-embedded substrate 1, uneven expansion can be suppressed.

[0049] Although embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above embodiments and can be applied to various embodiments. For example, in the above embodiments, as shown in Figure 2, the conductive particles 61 and 71 were randomly or evenly dispersed within the adhesive layers 63 and 73 in the adhesive films 60 and 70. However, the conductive particles 61 and 71 may be arranged adjacent to (unevenly distributed with) the metal foil layers 64 and 74. In this case, in the adhesive layers 63 and 73, the conductive particles 61 and 71 are not exposed on the side opposite to the metal foil layers 64 and 74, and the thickness of the portion of the adhesive layer 62 and 72 between the conductive particles 61 and 71 and the surfaces 65 and 75 of the metal foil layers 64 and 74 may be greater than 0 μm and less than or equal to 1 μm. In this case, since the conductive particles 61 and 71 are arranged adjacent to the metal foil layers 64 and 74, it becomes possible to more reliably flatten the conductive particles 61 and 71 into a flat shape by the metal foil layers 64 and 74. Furthermore, by localizing the conductive particles 61 and 71 on the metal foil layer 64 and 74 side in this manner, the capture rate of the conductive particles 61 and 71 by the wiring (electrodes) can be improved. In other words, the conductivity can be made more stable.

[0050] Alternatively, the adhesive layers 62 and 72 may be formed by dividing them into a first adhesive layer closer to the metal foil layers 64 and 74 and a second adhesive layer further away from the metal foil layers 64 and 74. The adhesive compositions constituting the first and second adhesive layers may be the same as those constituting the adhesive layers 62 and 72 described above, but conductive particles 61 and 71 may be dispersed only in the first adhesive layer, while conductive particles 61 and 71 are not dispersed in the second adhesive layer, i.e., they are not included. In this case as well, the conductive particles 61 and 71 are arranged adjacent to the metal foil layers 64 and 74, so that the conductive particles 21 can be more reliably flattened by the metal foil layers 64 and 74. Furthermore, by unevenly distributing the conductive particles 61 and 71 towards the metal foil layers 64 and 74 in this way, the capture rate of the conductive particles 61 and 71 to the wiring (electrodes), etc., can be improved. In other words, conductivity can be made more stable. [Explanation of Symbols]

[0051] 1...Component-embedded substrate, 2...Intermediate member, 3...First surface, 4...Second surface, 10...Electronic component, 11...First electrode, 12...Second electrode, 13...First surface, 14...Second surface, 20...First conductive layer, 21,61,61a...Conductive particles, 22...Curing adhesive layer, 23...First curing adhesive layer, 24,64...First metal foil layer, 31,71,71a...Conductive particles, 32...Curing adhesive layer, 33...Second curing adhesive layer, 34,74...Second metal foil layer, 40...First insulating resin layer, 42...Via conductor, 50...Second insulating resin layer, 60...First adhesive film, 62...Adhesive layer, 63...First adhesive layer, 65,75...Surface, 70...Second adhesive film, 72...Adhesive layer, 73...Second adhesive layer.

Claims

[Claim 1] A step of providing an intermediate member comprising an electronic component having a first electrode on its first surface, and a first conductive layer provided on the first surface of the electronic component so as to cover the first electrode, The process of forming a first insulating resin layer on the first surface of the intermediate member, Equipped with, The first conductive layer comprises a first cured adhesive layer comprising a cured adhesive layer containing conductive particles and a cured adhesive composition, and a first metal foil layer disposed on the first cured adhesive layer on the side opposite to the electronic component. A method for manufacturing a component-embedded substrate, wherein the conductive particles of the first curing adhesive layer electrically connect the first electrode of the electronic component and the first metal foil layer.

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