JP2022175734A - Wiring board, component built-in wiring board, and method for manufacturing component built-in wiring board - Google Patents

Abstract

To improve the quality of a wiring board.SOLUTION: A wiring board of an embodiment has: a first conductor layer 11a having a conductor pad 5 for component placement; a first insulating layer 12a formed on the first conductor layer 11a; a second conductor layer 11b formed on the first insulating layer 12a; a second insulating layer 12b formed on the second conductor layer 11b; and a recess 4 penetrating the second insulating layer 12b and the first insulating layer 12a to expose the conductor pad 5 on a bottom part. The recess 4 is formed to a depth allowing accommodation of the entirety of a component to be placed on the conductor pad 5. The thickness T4 of a part of the conductor pad 5 exposed in the recess 4 is smaller than the thickness T5 of a part of the first conductor layer 11a not exposed in the recess 4.SELECTED DRAWING: Figure 2

Description

The present invention relates to a wiring board, a wiring board with a built-in component, and a method of manufacturing a wiring board with a built-in component.

Patent Literature 1 discloses an electronic component built-in substrate. Electronic components are arranged in cavities formed in the wiring substrate by laser light. The entire bottom surface of the cavity where the electronic components are placed is composed of a solid conductor (copper) layer that serves as a laser light stopper layer. The electronic component is mounted on the stopper layer via an adhesive so as to have a gap between it and the inner wall of the cavity.

Japanese Patent Application Laid-Open No. 2006-19441

In the component built-in wiring board disclosed in Patent Document 1, the depth of the cavity is smaller than the thickness of the electronic component, and a part (electrode) of the electronic component protrudes outward from the cavity opening. With this configuration, it is considered that the dimension in the thickness direction of the wiring board with built-in component may increase.

A wiring board of the present invention comprises: a first conductor layer having a conductor pad for mounting a component; a first insulating layer formed on the first conductor layer; and a second insulating layer formed on the first insulating layer. a conductor layer; a second insulating layer formed on the second conductor layer; there is The recess is formed to have a depth capable of accommodating the entire component to be mounted on the conductor pad, and the thickness of the portion of the conductor pad exposed in the recess is equal to the thickness of the recess in the first conductor layer. Less than the thickness of the unexposed part.

A wiring board with a built-in component according to the present invention comprises the wiring board described above, an electronic component placed on the conductor pad in the recess, and the electronic component laminated on the surface of the wiring board and placed in the recess. and a sealing resin insulation layer that seals in.

A method of manufacturing a wiring board with a built-in component according to the present invention comprises: forming the wiring board described above so that the second conductor layer includes an alignment mark; mounting an electronic component on the conductor pad of the wiring board; housing an electronic component entirely within the recess; forming a third insulating layer within the recess and on the second insulating layer to seal the electronic component within the recess; there is Entirely accommodating the electronic component within the recess includes using the alignment marks to align the electronic component and the contact pads relative to each other.

According to the embodiments of the present invention, there are provided a wiring board, a wiring board with built-in component, and a method of manufacturing a wiring board with built-in component, which facilitates precise mounting of an electronic component at a desired position in a recess.

1 is a cross-sectional view showing an example of a wiring board according to one embodiment of the present invention; FIG. FIG. 2 is an enlarged view of a concave portion of the wiring board in FIG. 1; FIG. 4 is a cross-sectional view showing an example of a component built-in wiring board according to another embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board with a built-in component, which is another embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board with a built-in component, which is another embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a wiring board with a built-in component, which is another embodiment of the present invention;

A wiring board according to one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a wiring board 100, which is an example of a wiring board according to one embodiment. FIG. 2 shows an enlarged view of a region II surrounded by a dashed line in FIG.

As shown in FIG. 1, the wiring board 100 includes a core substrate 3 having two surfaces (an A surface 3a and a B surface 3b opposite to the A surface 3a) facing each other in the thickness direction; and a second buildup portion 2 laminated on the B surface 3b of the core substrate 3 . The core substrate 3 includes a resin insulation layer 30 (core substrate insulation layer), and conductor layers 31 (core substrate conductor layers) and The surface of conductor layer 31 on the first buildup portion 1 side and the exposed portion of the surface of resin insulation layer 30 on the first buildup portion 1 side constitute A surface 3a. The surface of conductor layer 31 on the second buildup portion 2 side and the exposed portion of the surface of resin insulation layer 30 on the second buildup portion 2 side constitute B surface 3b. The resin insulation layer 30 includes through-hole conductors 3c that pass through the resin insulation layer 30 and connect the conductor layer 31 on the A surface 3a side and the conductor layer 31 on the B surface 3b side.

The first buildup section 1 and the second buildup section 2 each include multiple insulating layers 12 and multiple conductor layers 11 . A plurality of insulating layers 12 and a plurality of conductor layers 11 are alternately laminated in each of the first and second buildup portions 1 and 2 . In wiring board 100 of FIG. 1 , first buildup section 1 includes five conductor layers 11 and six insulating layers 12 . Similarly, the second buildup section 2 includes five conductor layers 11 and six insulating layers 12 . The first buildup part 1 and the second buildup part 2 pass through each insulating layer 12 and are adjacent conductor layers (the conductor layers 11, or the conductor layer 11 and the core substrate conductor layer). 31) are included.

In the description of each embodiment, the side farther from the resin insulation layer 30 in the thickness direction of the wiring board is also referred to as "upper", "upper", or simply "upper", and the side closer to the resin insulation layer 30 is referred to as "upper". Also referred to as "lower" or "lower" or simply "lower". Furthermore, in each conductor layer and each insulating layer, the surface facing away from the resin insulation layer 30 is also referred to as the "upper surface", and the surface facing the resin insulation layer 30 is also referred to as the "lower surface". Therefore, for example, in the description of the first buildup section 1 and the second buildup section 2, the side farther from the core substrate 3 is also referred to as "upper", "upper", "upper layer side", or simply "upper". The side closest to is also referred to as "lower side", "lower", "lower side" or simply "lower".

The resin insulating layer 30 and the insulating layer 12 are made of any insulating resin. Examples of the insulating resin include epoxy resin, bismaleimide triazine resin (BT resin), and phenol resin. In the example of FIG. 1, the resin insulation layer 30 includes a core material (reinforcing material) 30a made of glass fiber or aramid fiber. Although not shown in FIG. 1, optional insulating layer 12 may include a core material such as glass fiber. Resin insulating layer 30 and insulating layer 12 may further contain an inorganic filler. Examples of the inorganic filler contained in each insulating layer include fine particles made of silica (SiO ₂ ), alumina, mullite, or the like.

The conductor layers 31 and 11, the through-hole conductors 3c and the via conductors 15 are formed using any metal such as copper or nickel. In the example of FIG. 1, the conductor layer 31 includes a metal foil 311, a metal film 312, and a plated film 313. In FIG. Through-hole conductor 3c is composed of metal film 312 and plating film 313 . Also, the conductor layer 11 and the via conductor 15 include a metal film 112 and a plated film 113 . A copper foil or a nickel foil is exemplified as the metal foil 311 . The plated films 313 and 113 are, for example, electrolytic plated films. The metal films 312 and 112 are, for example, electroless plated films or sputtering films, and function as power supply layers when the plated films 313 and 113 are formed by electrolytic plating, respectively.

The wiring board 100 of this embodiment has the recess 4 . The recessed portion 4 is a portion recessed from the surface 100a of the wiring board 100 on the first buildup portion 1 side toward the lower layer side (the core substrate 3 side). The recess 4 constitutes a cavity that accommodates an electronic component E mounted on the wiring board 100 .

The recess 4 exposes a conductor pattern included in any conductor layer 11 in the first buildup section 1 to its bottom surface. In the example of FIG. 1, the recess 4 exposes the conductor pads (component mounting pads) 5 included in the second conductor layer 11 from the surface 100a on the first buildup section 1 side. As will be described later in detail, the concave portion 4 is formed by irradiating a laser beam such as a carbon dioxide gas laser or a YAG laser from the surface 100a side to a position corresponding to the formation location of the concave portion 4 of the first buildup portion 1. can be formed with After the irradiation with the laser beam, the inner surface of the recess 4 is treated (desmear treatment and roughening treatment of the exposed surface of the conductor pad 5) using a chemical solution.

In the following description with reference to FIG. 2, the conductor layer including the conductor pads 5 exposed on the bottom surface of the recess 4 is referred to as the first conductor layer 11a. The insulating layer directly above the first conductor layer 11a is called a first insulating layer (first resin insulating layer) 12a. Furthermore, the conductor layer laminated on the first resin insulation layer 12a is also called the second conductor layer 11b. The second conductor layer 11b has an alignment mark 7 used for positioning when housing the electronic component E in the recess 4 (specifically, when placing it on the conductor pad 5) as part of its pattern. have. Insulation formed on the second conductor layer 11b and the first insulating layer 12a exposed from the conductor pattern of the second conductor layer 11b and constituting the outermost surface of the wiring board 100 (the outermost surface of the first buildup section 1) The layer is called a second insulation layer (second resin insulation layer) 12b. Second resin insulation layer 12b can function as a protective layer that protects second conductor layer 11b in processing using a chemical solution following irradiation of laser light in formation of concave portion 4 .

The wiring board of the embodiment includes at least a first conductor layer (11a) including the conductor pads (5), a first resin insulation layer (12a), a second conductor layer (11b), a second resin insulation layer (12b), and recesses (4). The recess 4 penetrates the second resin insulation layer 12b and the first resin insulation layer 12a, exposing a part of the conductor pad (component mounting pad) 5, which is a part of the conductor pattern of the first conductor layer 11a, to the bottom surface. there is The bottom surface of the recess 4 is configured by the conductor pad 5 . The conductor pads 5 function as component mounting pads for stably mounting the electronic component E on the wiring board. The electronic component E can be mounted on the conductor pads 5 via an adhesive 6, for example. The component mounting pads 5 can also function as electrodes for setting the back surface of the electronic component E (the surface facing the component mounting pads 5 when mounted) to a predetermined potential. In the illustrated example, the conductor pad 5 is a so-called solid pattern extending over the entire bottom surface of the recess 4 in the planar direction perpendicular to the thickness direction of the wiring board.

The recess 4 is formed to a depth that can completely accommodate the electronic component E to be accommodated therein. Preferably, the recess 4 is formed to a depth such that the upper surface of the electronic component E to be accommodated is substantially flush with the upper surface of the second resin insulation layer 12b.

If a design is adopted in which second resin insulation layer 12b is formed thick in order to make recess 4 deep enough to completely accommodate electronic component E, the size of wiring board 100 in the thickness direction increases. To address this problem, in the wiring board of the present embodiment, the conductor pads 5 are formed relatively thin. Specifically, the portion of the conductor pad 5 exposed to the bottom surface of the recess 4 is thinner than the thickness of the conductor pattern other than the conductor pad 5 in the first conductor layer 11a. More specifically, the thickness T4 of the portion exposed in the concave portion 4 is thinner than the thickness T5 of the peripheral portion of the conductor pad 5 covered with the first resin insulation layer 12a. Since the conductive pad 5 has such an aspect regarding its thickness, it is possible to completely accommodate the electronic component E in the concave portion 4 while suppressing an increase in the thickness of the second resin insulation layer 12b. Become. In other words, in the wiring board having the recess 4 for accommodating the electronic component E, an increase in dimension in the thickness direction is suppressed.

Further, when second resin insulation layer 12b is formed relatively thick, distance T between the upper surface of alignment mark 7 and the outermost surface of wiring board 100 (the upper surface of second resin insulation layer 12b) may increase. . When the electronic component E is accommodated in the recess 4, in that process, the position of the alignment mark 7 is recognized by a camera (not shown) provided outside the wiring substrate 100, and the electronic component E and the recess 4 are detected. (In particular, alignment with the contact pads 5) is performed. If the distance T between the upper surface of the second conductor layer 11b (especially the upper surface of the alignment mark 7) and the upper surface of the second resin insulation layer 12b is large, the accuracy of identification of the alignment mark 7 by the camera deteriorates. may not be placed exactly where requested. On the other hand, in the wiring board of the present embodiment, the conductive pads 5 are formed relatively thin, and the electronic component E can be completely placed in the concave portion 4 while suppressing an increase in the thickness of the second resin insulation layer 12b. can be accommodated. The alignment mark 7 can be identified with a high degree of accuracy by the camera, and a wiring board capable of accommodating the electronic component E in the concave portion 4 with a high degree of accuracy can be provided.

As a specific example, the thickness T4 of the portion of the conductor pad 5 exposed at the bottom of the recess 4 is smaller than the thickness T5 of the portion of the first conductor layer 11a not exposed at the bottom of the recess 4 by 2 μm or more. Also, the conductor pad 5 is formed so that the difference between the thickness T4 and the thickness T5 is 5 μm or less. The thickness T5 of the portion of the first conductor layer 11a not exposed to the bottom of the recess 4 is, for example, 15 μm, and the thickness T4 of the portion of the conductor pad 5 exposed to the recess 4 is 10 μm or more and 13 μm or less. can be

In addition, from the viewpoint of relatively reducing the thickness of second resin insulation layer 12b (particularly, distance T between the upper surface of alignment mark 7 and the upper surface of second resin insulation layer 12b) described above, the thickness of second resin insulation layer 12b The ratio of the thickness to the thickness of first resin insulation layer 12a is preferably 0.55 or less. From the viewpoint of protecting the second conductor layer 11b from the chemical in the process of forming the recess 4 using the chemical, the ratio of the thickness of the second resin insulation layer 12b to the thickness of the first resin insulation layer 12a should be 0. .4 or more is desirable. Specifically, for example, the thickness of first resin insulation layer 12a may be about 45 μm, and the thickness of second resin insulation layer 12b may be about 20 μm to 23 μm. From the same point of view, as a more specific example, the distance T between the upper surface of second resin insulation layer 12b and the upper surface of alignment mark 7 is preferably 5 μm or more and 8 μm or less.

In the illustrated example, the recessed portion 4 has a portion extending in the planar direction, that is, a recessed portion P, in the vicinity of the peripheral edge of the bottom of the recessed portion 4 in such a manner that the recessed portion 4 enters between the conductor pad 5 and the first resin insulation layer 12a. ing. Since the recess P is formed near the peripheral edge of the bottom of the recess 4, the electronic component E to be housed in the recess 4 can be more firmly and stably mounted on the conductor pad 5. Sometimes. The adhesive 6 interposed between the electronic component E and the conductor pad 5 spreads in the surface direction of the upper surface of the conductor pad 5, enters the recess P and solidifies, and the electronic component E is attached to the conductor pad 5. It may be fixed more firmly.

1 and 2, the wiring board 100 has been described as an example. , the second conductor layer 11b, the second resin insulation layer 12b, and the recesses 4 for exposing the conductor pads 5 are provided, and the core substrate 3 may not be provided. In addition, the first buildup section 1 and the second buildup section 2 may be composed of an arbitrary number of conductor layers 11 and insulating layers 12, and the number of layers is the first buildup section 1 and the second buildup section 1. Part 2 may be different. Also, the wiring board may be composed of only the first buildup section 1 without the second buildup section 2 . Further, there are cases where the alignment mark 7 is not used to house the electronic component E in the concave portion 4, and the second conductor layer 11b may not have the alignment mark 7. FIG.

Next, a wiring board with a built-in component, which is another embodiment of the present invention, will be described with reference to FIG. FIG. 3 shows a cross-sectional view of a component built-in wiring board 200 that is an example of another embodiment. As shown in FIG. 3, a component built-in wiring board 200 of this embodiment includes the wiring board of one embodiment described above. A component built-in wiring board 200 in the example of FIG. 3 includes the wiring board 100 illustrated in FIG. The component built-in wiring board 200 further includes an electronic component E and an insulating layer (sealing resin insulating layer or third insulating layer) 12e that seals the electronic component E. FIG. An electronic component E is housed in the recess 4 and bonded to the component mounting pad 5 using an adhesive 6 . Recess 4 is filled with the constituent material of sealing resin insulation layer 12e.

The electronic component E includes electrodes E1 used for connection between the electronic component E and an external circuit. Examples of electronic components E include active components such as semiconductor devices and passive components such as resistors. The electronic component E may be a wiring material including fine wiring formed on a semiconductor substrate. The electronic component E is entirely housed in the recess 4 . In the illustrated example, the electronic component E has the recess 4 such that the upper surface of the electronic component E (the upper surface of the electrode E1) is substantially flush with the upper surface of the insulating layer 12 forming the outermost surface of the wiring board 100. housed inside.

The component built-in wiring board 200 of FIG. 3 further includes a conductor layer 13 formed on the resin insulation layer 12e, a solder resist layer 8 covering the third insulation layer 12e and the conductor layer 13, and via conductors 150 and 15pe. contains. Conductive layer 13 formed on sealing resin insulation layer 12e includes connection pads 13p and 13pe used for connection with an external circuit. The solder resist layer 8 has openings that expose the connection pads 13p and 13pe. The via conductors 15pe penetrate the third insulating layer 12e on the electronic component E and connect the electrodes E1 of the electronic component E and the connection pads 13pe. Insulating layer 120 , conductor layer 130 , solder resist layer 80 , and via conductors 150 are formed on outermost resin insulating layer 12 of wiring board 100 on the side of second buildup portion 2 . Connection pads ( 130 p ) are exposed through openings provided in solder resist layer 80 .

Sealing resin insulation layer ( 12 e ) and resin insulation layer 120 can be formed using the same material as insulation layer 12 and the same method as insulation layer 12 . Sealing resin insulation layer 12 e for encapsulating electronic component E in concave portion 4 is laminated on upper side of first buildup portion 1 in wiring board 100 . Sealing resin insulation layer 12 e is laminated so as to cover electronic component E accommodated in cavity 4 . The electronic component E is sealed inside the recess 4 by the sealing resin insulation layer 12e. Via conductors (15pe) are formed on electrode E1 in sealing resin insulation layer (12e) and formed integrally with conductor layer (13).

Conductive layers 13 and 130 and via conductors 15pe and 150 are formed using materials similar to those of conductive layer 11 and via conductors 15, and may have structures similar to these. The solder resist layers 8 and 80 are formed using any insulating material such as epoxy resin or polyimide resin. Any material can be used for the adhesive 6 . Examples of the adhesive 6 include solder, a metal such as gold or copper, a conductive adhesive containing arbitrary conductive particles such as silver, and an insulating adhesive (for example, a die attach film ) and the like are exemplified.

A component built-in wiring board 200 of this embodiment includes a wiring board exemplified as the wiring board 100 in FIG. The portion of the conductor pad 5 exposed in the recess 4 is formed relatively thin, and is thinner than the thickness of the portion of the conductor layer 11 including the conductor pad 5 not exposed in the recess 4 . As a result, the wiring board with built-in component 200 accommodates the entire electronic component E in the recess 4, while suppressing an increase in dimension in the thickness direction. The thickness of the insulating layer 12b (see FIG. 2) covering the conductor layer 11 including the alignment marks 7 is suppressed and is relatively small. Therefore, in the component built-in wiring board 200 of the present embodiment, the electronic component E is arranged at a desired position within the recess 4 more precisely. Note that the wiring board 200 with a built-in component in the example of FIG. 3 may include a modified example of the wiring board 100 described, instead of the wiring board 100 itself illustrated in FIG.

Next, a wiring board manufacturing method according to one embodiment will be described with reference to FIGS. 4A to 4E using the wiring board 100 of FIG. 1 as an example.

As shown in FIG. 4A, a starting substrate (for example, a double-sided copper-clad laminate) including a resin insulation layer to be the resin insulation layer 30 of the core substrate 3 and metal foils laminated on both surfaces of the resin insulation layer. A conductor layer 31 of the core substrate 3 and through-hole conductors 3c are formed. For example, a through-hole is formed at the position where the through-hole conductor 3c is to be formed by drilling or irradiation with a carbon dioxide laser beam, and a metal film is formed in the through-hole and on the metal foil by electroless plating or sputtering. Then, a plated film is formed by electroplating using this metal film as a power supply layer. As a result, a conductor layer 31 having a three-layer structure and through-hole conductors 3c are formed. After that, by patterning the conductor layer 31 by a subtractive method, the core substrate 3 having a predetermined conductor pattern is obtained.

As shown in FIG. 4B , resin insulating layers 12 and conductor layers 11 are alternately formed on the A surface 3 a of the core substrate 3 . Resin insulating layers 12 and conductor layers 11 are also alternately formed on the B surface 3 b of the core substrate 3 . In FIG. 4B, after four layers of resin insulation layers 12 and three layers of conductor layers 11 are formed on the A surface 3a and the B surface 3b, respectively, a conductor layer (first conductor layer) 11a is further formed on the A surface 3a side. A conductor layer 11 is further formed on the B surface 3b side. The first conductor layer 11a is formed to have a thickness of, for example, about 15 μm.

The conductor pattern included in the first conductor layer 11 a is formed into a pattern including the conductor pads 5 . The conductor pads 5 on the first conductor layer 11a are formed in a region that can constitute the entire bottom surface of the recess 4 (see FIG. 2) for accommodating components, which is to be formed on the wiring board.

Next, as shown in FIG. 4C, on the A surface 3a side of the core substrate 3, the first insulating layer 12a is formed on the first conductor layer 11a, and further, the A surface 3a side is formed on the first insulating layer 12a. A second conductor layer 11b is formed as the outermost conductor layer in . The second conductor layer 11b is formed into a pattern including alignment marks 7 in its conductor pattern. A second insulating layer (second resin insulating layer) 12b is formed on the second conductor layer 11b as the outermost insulating layer on the A surface 3a side. The second insulating layer 12b is formed, for example, so that the ratio of the thickness of the second insulating layer 12b to the thickness of the first insulating layer 12a is 0.4 or more and 0.55 or less. Also, for example, the distance between the upper surface of the second conductor layer 11b and the upper surface of the second insulating layer 12b may be 5 μm or more and 8 μm or less. Similarly, on the B surface 3b side of the core substrate 3, a conductor layer 11 and an insulating layer 12 are formed as the outermost conductor layer and insulating layer on the B surface 3b side of the wiring board 100. FIG.

In forming the insulating layers 12, 12a, 12b, for example, a film-like epoxy resin is laminated on the core substrate 3 or on the previously formed insulating layers 12, 12a and conductor layers 11, 11a, 11b. , is heated and pressurized. As a result, each insulating layer 12, 12a, 12b is formed. Through holes for forming via conductors 15 are formed in the insulating layers 12, 12a, 12b by, for example, carbon dioxide laser light irradiation.

Each conductor layer 11, 11a, 11b is formed by, for example, a semi-additive method. That is, a metal film is formed by electroless plating or sputtering on the entire surface of the insulating layers 12, 12a underlying the conductor layers 11, 11a, 11b and in the through holes formed in the insulating layers 12, 12a. A plated film is formed by pattern plating including electrolytic plating using the metal film as a power supply layer. Via conductors 15 are formed in through-holes formed in each insulating layer 12, 12a. Thereafter, unnecessary portions of the metal film are removed by, for example, etching. As a result, each conductor layer 11, 11a, 11b having a two-layer structure including a predetermined conductor pattern is formed. Each conductor layer 11, 11a, 11b is formed using any metal such as copper or nickel.

As shown in FIG. 4D, a recess 4 is formed through the second insulating layer 12b and the first insulating layer 12a to expose a portion of the first conductor layer 11a, that is, a cavity in which an electronic component is to be accommodated. . In FIG. 4D, only the recess 4 and its peripheral portion are shown enlarged. The recesses 4 can be formed, for example, by irradiating the laser beam BM from the upper side of the outermost surface 100a on the side of the first buildup section 1 over the entire forming area of the recesses 4 while sending the laser light BM in pitch. A carbon dioxide gas laser beam is exemplified as the laser beam BM. The conductor pad 5 included in the first conductor layer 11a is formed in a region including the entire bottom surface of the recess 4 in plan view. Therefore, the conductor pad 5 can function as a stopper for the laser beam BM when forming the recess 4 .

The method for forming the recesses 4 is not limited to irradiation with the laser beam BM, and the recesses 4 may be formed by drilling, for example. Further, the recess 4 is formed by placing a peeling film (not shown) on the first conductor layer 11a to be the bottom surface of the recess 4 and removing the insulating layer and the conductor layer laminated on the peeling film. may

Next, as shown in FIG. 4E, after the recesses 4 are formed, the resin residue (smear) remaining in the recesses 4 is removed (desmear treatment) by, for example, a treatment using a chemical solution containing permanganate or the like. be. Subsequent to the desmearing process, the surface of the conductor pad 5 exposed to the recess 4 is subjected to a roughening process using a chemical solution. By roughening the exposed surface of the conductor pad 5 , the adhesion with an adhesive such as a die attach film interposed between the electronic component that can be mounted on the conductor pad 5 can be improved. The portion of the conductor pad 5 exposed to the concave portion 4 can be thinned by adjusting the processing time and the concentration of the chemical in this roughening processing. At the same time, the conductor pads 5 near the periphery of the bottom of the recesses 4 are partially removed to form recesses P having a shape that enters between the first resin insulation layer 12a and the conductor pads 5 .

In the roughening treatment, etching is performed using, for example, a sulfuric acid-hydrogen peroxide solution as a chemical solution. Partial removal of the conductor pads 5 in this roughening process is performed until the depth of the recesses 4 is such that the electronic components to be accommodated can be completely accommodated. In the roughening treatment, the conductor pad 5 can be treated, for example, so that the thickness of the portion exposed at the bottom of the recess 4 is reduced by 2 μm or more compared to the thickness before the roughening treatment is performed. It can be processed so as not to be smaller than 5 μm. As a result, the conductor pad 5 formed with a thickness of 15 μm, for example, can have a thickness of 10 μm or more and 13 μm or less at the portion exposed in the recess 4 . The wiring substrate 100 shown in FIG. 1 is completed through the above steps. In the desmearing process and the roughening process for forming the recesses 4, the second conductor layer 11b is protected from the chemical solution by the second insulating layer 12b. In particular, since the second insulating layer 12b has a thickness of 5 μm or more, the second conductor layer 11b is more reliably protected from the chemical solution.

Next, a method of manufacturing a wiring board with built-in component according to another embodiment will be described using the wiring board with built-in component 200 of FIG. 3 as an example with reference to FIGS. 5A to 5C.

First, a wiring board having cavities (recesses) for component mounting is prepared. For example, a wiring board 100 having recesses 4 is prepared using the wiring board manufacturing method described with reference to FIGS. 3A to 3E. FIG. 5A shows an enlarged view of the recess 4 of the prepared wiring board 100 and its peripheral portion.

As shown in FIG. 5A, the electronic component E is mounted on the conductor pads 5 exposed in the recess 4. As shown in FIG. For example, a metal pellet such as solder or copper, or a conductive or insulating paste or die attach film is supplied onto the conductor pads 5 as the adhesive 6 using a mounter or dispenser, and furthermore, the electronic component E is applied to the die bonder. and the like. The electronic component E is entirely housed in the recess 4 . As described above, the electronic component E is, for example, an active component such as a semiconductor device, a passive component such as a resistor, or a wiring material including fine wiring. The electronic component E and the adhesive 6 can be heated and pressed on the contact pads 5 , for example, thereby curing the adhesive 6 and bonding the electronic component E to the contact pads 5 . In the illustrated example, the upper surface of the electronic component E is substantially flush with the upper surface of the second insulating layer 12b when joined to the conductor pads 5. As shown in FIG. Although different from the illustrated example, when the adhesive 6 spreads in the planar direction of the conductor pad 5 and fills the recessed portion P and hardens, the electronic component E is firmly bonded to the conductor pad 5. There is

In the step of placing electronic component E in recess 4 , alignment mark 7 is recognized by an alignment camera (not shown) arranged above wiring board 100 . Specifically, the alignment camera recognizes the alignment mark 7 that penetrates the second insulating layer 12b. The relative positional relationship between the electronic component E and the wiring substrate 100 (in particular, the recess 4) is adjusted based on the positional information from the alignment marks 7. FIG. The alignment mark 7 has, for example, a circular planar shape in plan view. In the method for manufacturing a wiring board with a built-in component according to the present embodiment, the thickness of the conductor pad exposed at the bottom of the recess that can accommodate the entire electronic component in the wiring board is such that the thickness of the conductor pad exposed in the recess in the conductor layer including the conductor pad is large. It is formed thinner than the thickness of the part where it is not. Therefore, the second insulating layer 12b covering the alignment mark 7 can be formed relatively thin, and the distance T between the upper surface of the alignment mark 7 and the upper surface of the second insulating layer 12b is relatively small. Therefore, recognition of the alignment mark 7 by the alignment camera can be performed more precisely. The relative positions of the electronic component E and the wiring board 100 are precisely adjusted, and the electronic component E can be arranged at a more desirable position within the recess 4 .

Next, as shown in FIG. 5B, a third insulating layer (sealing resin insulating layer) 12e is formed to cover the electronic component E, and the concave portion 4 is filled with the material of the third insulating layer 12e. As a result, the electronic component E is sealed within the recess 4 . In the example of FIG. 5B , sealing resin insulation layer 12 e is formed on outermost second insulation layer 12 b of first buildup section 1 . An insulating layer 120 is also formed on the outermost insulating layer 12 in the buildup portion 2 on the opposite side of the recess 4 with respect to the core substrate 3 .

At the time of forming sealing resin insulation layer 12e, for example, a film-like epoxy resin or the like, which is laminated to form sealing resin insulation layer 12e, flows into concave portion 4 by heating and pressurizing. Then, the inside of the concave portion 4 is filled with a material forming the sealing resin insulation layer 12e, such as an epoxy resin. Further, the electronic component E is sealed in the concave portion 4 with epoxy resin or the like forming the sealing resin insulating layer 12e.

As shown in FIG. 5C, via conductors (150, 15pe) penetrating sealing resin insulation layer (12e) and conductor layer 13 on sealing resin insulation layer (12e) are formed. Via conductors 150 passing through insulating layer 120 and conductor layer 130 on insulating layer 120 are also formed on the opposite side of core substrate 3 . The conductor layer 13 is provided with connection pads 13p and 13pe used for connection with an external circuit. The conductor layer 130 is also provided with connection pads 130p. Conductive layer 13 is connected to outermost second conductor layer 11b of first buildup section 1 by via conductors 150 penetrating sealing resin insulating layer 12e and outermost second insulating layer 12b of first buildup section 1 . connected with The connection pads 13pe are connected to the electrodes E1 of the electronic component E by via conductors 15pe penetrating the third insulating layer 12e on the electronic component E. FIG.

Conductor layer 13 and conductor layer 130 and via conductors 150 and 15pe can be formed using the same method and material as the method for forming conductor layer 11 and via conductor 15 described above. Regarding the formation of via conductors (15pe), through holes are formed to expose electrodes E1 of electronic component E by irradiating, for example, ultraviolet (UV) laser light from the surface of resin insulation layer 12e toward electrodes E1. Forming the conductor layer 13 and filling the plated film in the through hole form the via conductor 15pe that connects the conductor layer 13 (specifically, the connection pad 13pe) and the electrode E1.

After that, a solder-resist layer 8 is formed on the conductor layer 13 and the sealing resin insulation layer 12e, and a solder-resist layer 80 is formed on the conductor layer 130 and the insulation layer 120 (see FIG. 3). The solder resist layer 8 is provided with openings for exposing the connection pads 13p and 13pe, and the solder resist layer 80 is provided with openings for exposing the connection pads 130p. The solder resist layers 8, 80 and openings in each solder resist layer are formed by forming a resin layer containing a photosensitive epoxy resin, polyimide resin, or the like, and exposing and developing using a mask having an appropriate opening pattern. be.

On the connection pads 13p, 13pe, 130p exposed in the openings of the solder resist layers 8, 80, Au, Ni/Au, Ni/Pd/Au, solder or A surface protective film (not shown) made of heat-resistant preflux or the like may be formed. Through the above steps, the component built-in wiring board 200 in the example of FIG. 3 is completed.

The method for manufacturing the wiring board and the method for manufacturing the component built-in wiring board described above are not limited to the methods described with reference to the drawings, and the conditions, order, and the like may be changed as appropriate. Some of the steps may be omitted, or other steps may be added, depending on the structure of the wiring board that is actually manufactured.

REFERENCE SIGNS LIST 100 Wiring board 200 Component built-in wiring board 1 First buildup section 2 Second buildup section 3 Core substrate 4 Recess 5 Conductor pad (component mounting pad)
REFERENCE SIGNS LIST 11 conductor layer 11a first conductor layer 11b second conductor layer 12 resin insulation layer 12a first insulation layer (first resin insulation layer)
12b Second insulation layer (second resin insulation layer)
12e third insulation layer (sealing resin insulation layer)
13, 130 conductor layer 13p, 13pe, 130p connection pad 7 alignment mark 8, 80 solder resist layer E electronic component BM laser light

Claims (12)

a first conductor layer having a component mounting conductor pad; a first insulating layer formed on the first conductor layer; a second conductor layer formed on the first insulating layer; A wiring board comprising: a second insulating layer formed on a conductor layer;
The recess is formed to have a depth capable of accommodating the entire component to be mounted on the conductor pad,
The thickness of the portion of the conductor pad exposed in the recess is smaller than the thickness of the portion of the first conductor layer not exposed in the recess. 2. The wiring board according to claim 1, wherein said second conductor layer includes an alignment mark used for relative alignment of a component to be mounted on said conductor pad and said conductor pad. 2. The wiring board according to claim 1, wherein the difference between the thickness of the portion of the conductor pad exposed to the recess and the thickness of the portion of the first conductor layer not exposed to the recess is 2 μm or more, and , 5 μm or less. 2. The wiring board according to claim 1, wherein the ratio of the thickness of said second insulating layer to the thickness of said first insulating layer is 0.4 or more and 0.55 or less. 2. The wiring board according to claim 1, wherein the entire upper surface of said second conductor layer is covered with said second insulating layer. 2. The wiring board according to claim 1, wherein the distance between the upper surface of said second insulating layer and the upper surface of said second conductor layer is 5 [mu]m or more and 8 [mu]m or less. 2. The wiring board according to claim 1, wherein the thickness of the portion of said conductor pad exposed in said recess is 10 [mu]m or more and 13 [mu]m or less. 2. The wiring board according to claim 1, wherein the end of said conductor pad is covered with said first insulating layer, and the thickness of the portion of said conductor pad exposed in said recess is equal to the thickness of said end of said conductor pad. less than the thickness at 9. The wiring board according to claim 8, wherein a recess is formed in the peripheral edge of the bottom of the recess to extend the area of the recess in a plane direction. 2. The wiring board according to claim 1, an electronic component placed on said conductive pad in said recess, and a sealing layer laminated on the surface of said wiring board for sealing said electronic component in said recess. A wiring board with a built-in component, comprising: a resin insulating layer; forming the wiring substrate according to claim 1 such that the second conductor layer includes an alignment mark;
mounting an electronic component on the conductor pad of the wiring board, and accommodating the entire electronic component in the recess;
forming a third insulating layer in the recess and on the second insulating layer to seal the electronic component in the recess;
A method for manufacturing a wiring board with built-in components,
Entirely accommodating the electronic component within the recess includes using the alignment marks to align the electronic component and the contact pads relative to each other. 12. The method of manufacturing a wiring board with a built-in component according to claim 11, wherein the wiring board is prepared such that the distance between the upper surface of the alignment mark and the upper surface of the second insulating layer is 5 μm. above, and includes forming to be 8 μm or less.

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