JP2020092210A - Printed wiring board and manufacturing method of the same - Google Patents

Abstract

To provide a method of manufacturing a printed wiring board having a recess.SOLUTION: The manufacturing method includes: forming a metal protective layer on a first insulating layer 10; forming a buildup layer 3 on the metal protective layer; forming a recess 2 for exposing the metal protective layer by removing a part of the buildup layer 3; and removing a portion of the metal protective layer exposed in the recess 2. Forming the metal protective layer includes: forming a first metal protective layer; and forming a second metal protective layer of a material different from a material of the first metal protective layer. Removing the portion of the metal protective layer includes etching away the second metal protective layer to expose the first metal protective layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a printed wiring board having a recess.

In Patent Document 1, a first buildup layer is formed on a core substrate formed by processing a double-sided copper-clad laminate, and an electronic component is mounted in a cavity formed in the first buildup layer. A substrate with a built-in electronic component is disclosed. The bottom surface of the cavity is composed of a stopper layer made of copper, and electronic components are fixed to the stopper layer with an adhesive.

JP 2006-19441 A

In the electronic component-embedded substrate of Patent Document 1, the cavity is formed by performing laser processing using a stopper layer whose processing speed by laser light is slower than that of an insulating layer made of resin. It is considered difficult to form the bottom surface of the cavity flat.

A method of manufacturing a printed wiring board having a recess according to the present invention comprises: preparing an insulating layer having a first surface; forming a metal protective layer on the first surface; and forming a conductor on the metal protective layer. Forming a build-up layer in which layers and insulating layers are alternately laminated, forming a recess for exposing the metal protective layer by removing a part of the build-up layer, and exposing the recess Removing a portion of the metal protective layer that has been removed. Then, forming the metal protective layer includes forming a first metal protective layer and forming a metal protective layer from a material different from the material of the first metal protective layer so as to overlap the first metal protective layer in a plan view. Removing a portion of the metal protective layer comprises exposing the first metal protective layer by removing the second metal protective layer with an etchant. It includes making things happen.

According to the embodiment of the present invention, it is possible to form the recess having excellent flatness on the bottom surface at an arbitrary position in the buildup layer of the printed wiring board.

Sectional drawing which shows an example of the printed wiring board manufactured in one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of a reference example. The figure which shows an example of the manufacturing method of the printed wiring board of a reference example. The figure which shows an example of the manufacturing method of the printed wiring board of a reference example. The figure which shows an example of the manufacturing method of the printed wiring board of a reference example. The figure which shows an example of the manufacturing method of the printed wiring board of a reference example. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention. The figure which shows an example of the manufacturing method of the printed wiring board of other embodiment of this invention.

An embodiment of a method for manufacturing a printed wiring board of the present invention will be described with reference to the drawings. FIG. 1 shows a partial cross-sectional view of a printed wiring board 1 which is an example of a printed wiring board manufactured by a method for manufacturing a printed wiring board according to an embodiment of the present invention. The manufacturing method of one embodiment is illustrated in Figures 2A-2H. As shown in FIG. 1, the printed wiring board 1 includes a first insulating layer 10 having a first surface 10F, and a first conductor layer 11 provided on the first surface 10F of the first insulating layer 10. At least one set of the insulating layer 10a and the conductor layer 11a laminated on the first insulating layer 10 and the first conductor layer 11 and the recess 2 exposing the first conductor layer 11 on the bottom surface are provided. In the example of FIG. 1, a total of five insulating layers 10a and a total of five conductive layers 11a are alternately stacked on the first surface 10F of the first insulating layer 10 and on the first conductor layer 11. Five sets of insulating layers 10a and conductor layers 11a are laminated. The recess 2 penetrates the at least one set of the insulating layer 10a and the conductor layer 11a.

The bottom surface of the recess 2 is formed by an exposed portion of the surface of the first conductor layer 11 opposite to the first insulating layer 10. An electronic component such as a semiconductor device mounted on the printed wiring board 1 is mounted inside the recess 2 by being bonded to the first conductor layer 11 exposed at the bottom of the recess 2 with a conductive adhesive or the like. .. A plurality of electronic components may be mounted inside the recess 2. Any number of electronic components can be mounted. Moreover, the printed wiring board 1 may be provided with a plurality of recesses 2 at desired positions.

In the present embodiment, the bottom surface of the recess 2 is formed of a metal layer having excellent flatness and a clean surface. When the printed wiring board 1 is used, electronic components can be stably and reliably mounted inside the recess 2. In a method for manufacturing a printed wiring board 1 according to an embodiment to be described later, a method for forming the recess 2 having such a bottom surface at an arbitrary position in the printed wiring board will be described.

The first insulating layer 10 and the insulating layer 10a and the first conductor layer 11 and the conductor layer 11a constitute a so-called build-up layer 3. In the example shown in FIG. 1, the buildup layer 3 includes six conductor layers (first conductor layer 11 and conductor layer 11a) and insulating layers (first insulating layer 10 and insulating layer 10a) interposed between the conductor layers. And a laminate. Each of the conductor layers (first conductor layer 11 and conductor layer 11a) is appropriately patterned so as to have a desired conductor pad and/or wiring pattern. Each insulating layer (first insulating layer 10 and insulating layer 10a) includes a plurality of via conductors 12 that connect the upper and lower conductor layers of each insulating layer.

In the example shown in FIG. 1, the printed wiring board 1 includes a solder resist layer 5 on the outermost insulating layer 10a and the conductor layer 11a of the buildup layer 3. The solder resist layer 5 has an opening 5c that exposes a conductor pad of the outermost conductor layer 11a of the buildup layer 3.

Each conductor layer (first conductor layer 11 and each conductor layer 11a) and each via conductor 12 is preferably a metal conductor, for example, a metal foil such as a copper foil, and/or electrolytic or electroless plating of copper. Composed of a membrane. Although not shown, for example, the first conductor layer 11 and each conductor layer 11a of the buildup layer 3 of the printed wiring board 1 of FIG. 1 are formed in a two-layer structure including an electroless plating film and an electrolytic plating film, respectively. Can be done.

The first insulating layer 10 and the insulating layer 10a are formed of an organic resin material such as an epoxy resin, a bismaleimide triazine resin (BT resin), or a phenol resin. The organic resin material may be an epoxy resin or the like containing no reinforcing material, or may be a material obtained by impregnating a reinforcing material such as glass fiber with epoxy or another resin composition. The resin composition such as epoxy may contain an inorganic filler such as silica. Further, the electronic component placed in the recess 2 at the time of mounting is not particularly limited. Semiconductor integrated circuit devices such as a microcomputer, a gate array, and a memory are mainly exemplified.

As described above, the recess 2 is formed so as to penetrate at least one set of the insulating layer 10a and the conductor layer 11a in the buildup layer 3. In the example of FIG. 1, the recess 2 penetrates five sets of the insulating layer 10a and the conductor layer 11a. The size of the conductor pattern of the first conductor layer 11 forming the bottom surface of the recess 2 in plan view is larger than the opening area of the recess 2, and the outer edge of this conductor pattern in plan view is larger than the inner wall of the recess 2 It is located on the outer peripheral side of. Further, the inner wall of the recess 2 has a recess that is recessed toward the outside of the recess 2 near the bottom surface of the recess 2.

The size of the recess 2 can be designed according to the size of the electronic component to be mounted. For example, the depth D of the recess 2, that is, the buildup of the surface of the outermost layer of the buildup layer 3 (the solder resist layer 5 in the example of FIG. 1) and the exposed surface of the first conductor layer 11 in the recess 2 The difference in height of the layers 3 in the stacking direction is not limited to the example of FIG. The depth D of the recess 2 can be easily adjusted by appropriately selecting the number of sets of the insulating layer 10a and the conductor layer 11a to be penetrated according to the height of the electronic component placed inside.

An example of the method for manufacturing the printed wiring board of the embodiment (first embodiment) including forming such recesses 2 in the printed wiring board 1 will be described with reference to the printed wiring board 1 shown in FIG. 2A to 2H will be specifically described. It should be noted that the attached drawings are not intended to show the exact ratios of the sizes and shapes of the respective components of the printed wiring board.

First, the buildup layer 3 is formed on one surface of, for example, a core substrate. As the core substrate, for example, a double-sided copper-clad laminate including an insulating layer serving as a core portion can be used. Then, a double-sided copper-clad laminate having a conductor layer formed by a subtractive method may be used. However, the conductor layer may be formed on one surface of the insulating layer by an additive method without using the double-sided copper-clad laminate. Next, the insulating layers and the conductor layers of the buildup layer 3 are alternately laminated on the insulating layer and the conductor layer which will be the core portion.

FIG. 2A shows that, after a predetermined number of insulating layers and conductive layers among the insulating layers and the conductive layers forming the build-up layer 3 are alternately laminated, the first conductive layer 11 serving as the bottom surface of the recess 2 is formed. The process shown is shown. The first conductor layer 11 can be formed at any position on the buildup layer 3. Therefore, the position where the first conductor layer 11 is formed is appropriately selected according to the desired depth D of the recess 2.

First, as shown in FIG. 2A, the first insulating layer 10 that covers the conductor layer 11c, which is one layer inside from the first conductor layer 11 on the core substrate side, is formed by thermocompression-bonding a film-shaped epoxy resin or the like. It Next, a through hole 101 that penetrates the first insulating layer 10 is formed at the formation location of the via conductor 12 by irradiating a predetermined position with, for example, carbon dioxide laser light. Then, the first conductor layer 11 having a desired conductor pattern is formed by using, for example, a semi-additive method, which includes, for example, an electroless plating film of copper (not shown) and an electrolytic plating film of copper (not shown). It At the same time, the via conductor 12 including an electroless plating film (not shown) of copper and an electrolytic plating film (not shown) is formed.

The first conductor layer 11 is formed to have a desired conductor pattern. Particularly when the printed wiring board 1 illustrated in FIG. 1 is manufactured, as shown in FIG. 2A, the first conductor layer 11 is formed in a predetermined region where the recess 2 is formed as a part of the conductor pattern. , The first pattern 11p, which is the first metal protective layer 21, is formed. The surface of the first metal protective layer 21 opposite to the first insulating layer 10 forms the bottom surface of the recess 2 as shown in FIG.

As shown in FIG. 2B, subsequently, the second metal protective layer 22 is laminated on the first metal protective layer 21 so as to overlap with the first metal protective layer 21 in a plan view, for example, by a pattern plating method. The first metal protective layer 21 and the second metal protective layer 22 are preferably made of different materials. For example, the first metal protective layer 21 is made of copper, and the second metal protective layer 22 is made of nickel, for example. In the embodiment of the method for manufacturing the printed wiring board 1 shown in FIGS. 2A to 2H, the metal protective layer 20 is formed by the first metal protective layer 21 and the second metal protective layer 22. The metal protective layer 20 may be formed by forming two or more metal protective layers on the first metal protective layer 21. That is, as shown by the chain double-dashed line in FIG. 2B, the third metal protective layer 23 is formed on the second metal protective layer 22 so as to further overlap in a plan view, and the first to third metal protective layers 21 to 21. The metal protective layer 20 may be composed of 23. In this case, the third metal layer 23 is formed of a material different from the material of the second metal protective layer 22, for example, copper.

Next, as shown in FIG. 2C, the insulating layer 10a is formed by laminating, for example, a film-shaped epoxy resin or prepreg on the first insulating layer 10, the first conductor layer 11 and the metal protective layer 20. ..

Subsequently, as shown in FIG. 2D, a through hole 101 for the via conductor 12 (see FIG. 1) is formed in the insulating layer 10a by laser processing or drill processing.

Then, as shown in FIG. 2E, the conductor layer 11a and the via conductor 12 having a desired conductor pattern are respectively formed by using, for example, a semi-additive method. The build-up layer 3 is completed by repeating the same process a desired number of times (four times in the example of FIG. 2E). Although not formed in the example of FIG. 2E, a dummy pattern may be provided in each conductor layer 11a in the formation region of the recess 2.

In the manufacture of the printed wiring board 1 illustrated in FIG. 1, the solder resist layer 5 is formed on the buildup layer 3 as shown in FIG. 2F. The solder resist layer 5 is formed using, for example, a photosensitive epoxy resin or polyimide resin. An opening 5c is formed in the solder resist layer 5 by exposure and development.

After that, as shown in FIG. 2G, the recess 2 is formed in a part of the buildup layer 3. The recess 2 can be formed by excavating a predetermined region of the buildup layer 3 by mechanical processing such as drilling from the solder resist 5 side. Part of the insulating layer 10a, the conductor layer 11a, and the solder resist layer 5 in the buildup layer 3 corresponding to the region where the recess 2 is formed are removed. The removal is performed so that the entire surface of the metal protection layer 20 opposite to the first insulating layer 10 (in the example of FIG. 2G, the surface of the second metal protection layer 22 opposite to the first metal protection layer 21) is exposed. It is done by excavating. The concave portion 2 is formed so that the metal protective layer 20 is exposed at the bottom.

Next, as shown in FIG. 2H, the second metal protective layer 22 which is the portion exposed at the bottom of the recess 2 of the metal protective layer 20 is removed by etching using an etching solution, and the first metal protective layer is removed. 21 is exposed at the bottom of the recess 2. As the etching liquid, for example, an etching liquid having an etching rate with respect to the second metal protective layer 22 higher than that with respect to the first metal protective layer 21 is used. Thereby, only the second metal protective layer 22 can be removed. As a result, the first metal protective layer 21 is exposed at the bottom of the recess 2.

As described above, when excavation is performed by drilling to form the recessed portion 2, the surface of the metal protective layer 20 exposed at the bottom of the recessed portion 2 after excavation is roughened by cutting marks by the drill. In addition, a residue or the like generated by drilling may remain on the exposed surface of the metal protective layer 20, and in such a case, the residue needs to be removed from the recess 2. According to the manufacturing method illustrated in FIGS. 2A to 2H described above, the portion of the metal protective layer 20 in which the cutting traces formed by the drilling are formed is included in the second metal protective layer 22, and this portion is , The second metal protective layer 22 is removed by etching. The etching exposes the interface between the second metal protective layer 22 and the first metal protective layer 21. That is, the clean and flat surface of the first metal protective layer 21 is exposed as the bottom surface of the recess 2. At the time of etching, the residue generated by drilling or the like is also removed, so that the flatness of the bottom surface of the recess 2 is further improved. The electronic components mounted inside the recess 2 can be mounted stably and with high reliability.

When the metal protective layer 20 is composed of three or more metal protective layers, for example, the third metal protective layer 23 is formed on the second metal protective layer 22, and the first to third metal protective layers 21 are formed. , 22, 23 when the metal protective layer 20 is formed, for example, the third metal protective layer 23 is formed of copper, the second metal protective layer 22 is formed of nickel, and the first metal protective layer 21 is formed of the first metal protective layer 21. It can be formed of copper as a part of the one conductor layer 11. In such a case, first, the third metal protective layer 23 is etched by an acidic etching solution in which the etching rate for copper is higher than the etching rate for nickel, for example, a mixture of sulfuric acid and hydrogen peroxide. As a result, the second metal protective layer 22 is exposed. Then, the second metal protective layer 22 is etched using an etching solution having a higher etching rate for nickel than that for copper, for example, an aqueous solution containing nitric acid and sulfuric acid as main components. The third metal protective layer 23 is used as a stopper for laser light, but since the third metal protective layer 23 is made of copper, it is considered that it functions well as a stopper. In addition, since a stronger etchant can be used for the second metal protective layer 22 than the first and third metal protective layers 21 and 23, the first metal exposed after the etching of the second metal protective layer 22 is performed. The surface of the protective layer 21 can be a cleaner surface.

According to the manufacturing method illustrated in FIGS. 2A to 2H, it is possible to form the recess 2 having excellent flatness of the bottom surface at an arbitrary position of the buildup layer 3. However, for example, the first insulating layer 10 on which the metal protective layer 20 is provided may be the insulating layer of the core substrate. In this case, the recess 2 can be provided on the core substrate.

An embodiment (second embodiment) in which the concave portion 2 is provided on the core substrate will be described below with reference to FIGS. First, as shown in FIG. 3A, a double-sided copper-clad laminate having an insulating layer 30a as an insulating layer serving as a core is prepared. The double-sided copper-clad laminate has a copper foil 301 serving as the first conductor layer 11 on the first surface 30F of the insulating layer 30a and a copper foil 302 serving as the second conductor layer 32 on the second surface 30S of the insulating layer 30a. I have it.

As shown in FIG. 3B, a through hole is formed at the position where the through-hole conductor 35 is formed by drilling or laser processing the insulating layer 30a. Then, using a subtractive method, for example, a copper foil (not shown), a copper electroless plating film (not shown), and a copper electrolytic plating film (not shown) are included and have a desired conductor pattern. The first conductor layer 11 and the second conductor layer 32 are formed. At the same time, a through-hole conductor 35 including a copper electroless plating film and an electrolytic plating film is formed. An additive method may be used to form the first and second conductor layers 11 and 32 and the through-hole conductor 35.

The first and second conductor layers 11 and 32 are formed so as to have a desired conductor pattern. Similar to the manufacturing method illustrated in FIGS. 2A to 2H, the first conductor layer 11 is a first pattern that is the first metal protective layer 21 in a predetermined region where the recess 2 is formed as a part of the conductor pattern. 11p is formed.

Subsequently, as shown in FIG. 3C, the second metal protective layer 22 is laminated on the first metal protective layer 21 so as to overlap with the first metal protective layer 21 in a plan view, for example, by the same method as the step shown in FIG. 2B. The metal protective layer 20 is formed.

Then, as shown in FIGS. 3D and 3E, for example, in the same manner as the steps shown in FIGS. 2C to 2E, the first surface 30F of the insulating layer 30a, the first conductor layer 11, and the metal protective layer 20 are formed. The buildup layer 3 is formed by alternately stacking a plurality of insulating layers 10a and conductor layers 11a. Further, the solder resist layer 5 is formed on the buildup layer 3. Preferably, at the same time when the buildup layer 3 is formed, a plurality of insulation layers 10a and conductor layers 11a are laminated on the second surface 30S of the insulation layer 30a and the second conductor layer 32 to form the buildup layer 33. It

After that, as shown in FIG. 3F, the recess 2 is formed in the build-up layer 3 by a method similar to the steps shown in FIGS. 2F to 2H, for example. The buildup layer 3 is excavated from the solder resist 5 side shown in FIG. 3F until the surface of the metal protective layer 20 opposite to the first insulating layer 10 is exposed, and the buildup layer 3 in the region where the recess 2 is formed. Are removed.

Then, as shown in FIG. 3G, the second metal protective layer 22 exposed at the bottom of the recess 2 is removed by etching using an etchant. The clean and flat surface of the first metal protective layer 21 is exposed. In the printed wiring board 1 a of the present embodiment, the first conductor layer 11 on the core substrate 30 constitutes the first metal protective layer 21 and is exposed on the bottom surface of the recess 2. In the printed wiring board 1a, heat generated from the electronic component mounted in the recess 2 is passed through the buildup layer 33 using the first conductor layer 11 of the core substrate 30 and the through-hole conductor 35, and the recess of the core substrate 30 is formed. Heat can be efficiently radiated to the side opposite to the side where 2 is formed.

A reference example in which the recess 2 is formed so as to penetrate the core substrate 30 will be described with reference to FIGS. In this reference example, the metal protective layer 20 is provided on the lower surface of the core substrate 30, that is, on the second surface 30S that is the surface opposite to the side (first surface 30F) where the recess 2 is formed in the core substrate 30. It is provided. In the example of FIGS. 4A to 4E, the metal protective layer 20 is composed of the first to third metal protective layers 21 to 23.

As shown in FIG. 4A, first, on the second surface 30S of the insulating layer 30a of the core substrate 30, among the first to third metal protective layers 21 to 23 forming the metal protective layer 20, the third metal protective layer is formed. The layer 23 is formed in a predetermined region where the recess 2 is formed so as to contact the insulating layer 30a.

Next, as shown in FIG. 4B, the second metal protective layer 22 is laminated on the third metal protective layer 23 so as to be overlapped in a plan view, and further, the second metal protective layer 22 is further overlapped on the second metal protective layer 22 in a plan view. The first metal protection layer 21 is laminated on the. The second and first metal protective layers 22 and 21 are laminated by, for example, a pattern plating method. As a result, the metal protective layer 20 having a three-layer structure is formed. The third metal protective layer 23 and the first metal protective layer 21 are made of, for example, copper, and the second metal protective layer 22 is made of, for example, nickel.

Thereafter, as shown in FIG. 4C, at least one set of insulating layer 10a and conductor is provided on the first surface 30F of the insulating layer 30a, and on the second surface 30S and the metal protective layer 20, respectively, by an arbitrary method. Build-up layers 3 and 33 including layer 11a are formed. Further, the solder resist layer 5 is formed.

Then, as shown in FIG. 4D, the recess 2 is formed by excavating the buildup layer 3 by, for example, drilling. In the present reference example, the excavation for forming the recess 2 is performed from the surface of the buildup layer 3 formed on the side of the core substrate 30 opposite to the side on which the metal protective layer 20 is provided (see FIG. 4D). In this example, it is performed so as to penetrate the core substrate 30) (from the side of the solder resist layer 5 provided on the surface of the build-up layer 3).
After excavation, as shown in FIG. 4D, the surface of the third metal protective layer 23 is exposed at the bottom surface of the recess 2.

As shown in FIG. 4E, the third metal protective layer 23 is removed by etching, and the second metal protective layer 22 is further removed by etching. By removing the third and second metal protective layers 23 and 22 by etching, the bottom surface of the concave portion 2 exposes a clean and flat surface of the first metal protective layer 21. In the present reference example, since the recess 2 is formed so as to penetrate the core substrate 30, the recess 2 having a deeper depth can be easily formed in the printed wiring board.

An embodiment (third embodiment) in which the recess 2 is formed by laser processing will be described with reference to FIGS. As in the present embodiment, the removal of the buildup layer 3 for forming the recess 2 may be performed by laser processing instead of drilling.

As shown in FIG. 5A, first, similarly to FIG. 2B, the first conductor layer 11 including the first pattern 11p serving as the first metal protective layer 21 is formed on the first insulating layer 10. Then, the second metal protective layer 22 is laminated on the first metal protective layer 21 to form the metal protective layer 20 including the first metal protective layer 21 and the second metal protective layer 2.

Subsequently, as shown in FIG. 5B, the metal protective layer 20 (in the case of FIG. 5B, the second metal is formed) at a position overlapping with the metal protective layer 20 on the metal protective layer 20 in a plan view, that is, in the formation region of the recess 2. A peeling film 25 is provided that does not adhere firmly to the protective layer 22) and is easily peeled off, but firmly adheres to the insulating layer 10a of the buildup layer 3.

Next, as shown in FIG. 5C, the buildup layer 3 is formed on the first insulating layer 10, the first conductor layer 11 and the peeling film 25 by an arbitrary method.

Further, as shown in FIG. 5D, the metal protective layer 20 (in the case of FIG. 5D, the second protective layer 20 is formed by irradiating a laser beam such as a carbon dioxide gas laser or a YAG laser to the entire periphery of the region where the recess 2 is formed. A frame-shaped groove having the bottom of the metal protective layer 22) is formed. At this time, the second metal protective layer 22 can function as a stopper for laser light.

As shown in FIG. 5E, a region of the buildup layer 3 surrounded by the groove is fixed to, for example, a jig and removed by pulling the jig and the like. Since the adhesion between the second metal protective layer 22 and the release film 25 is not as strong as the adhesion between the insulating layer 10a of the buildup layer 3 and the release film 25, the second metal protection layer 22 and the release film 25 are compared. Can be easily peeled off. A region of the buildup layer 3 surrounded by the groove is removed together with the peeling film 25. As a result, the surface of the second metal protective layer 22 is exposed.

Then, as shown in FIG. 5F, the second metal protective layer 22 is removed by etching, as in the case where the formation region of the recess 2 in the buildup layer 3 is removed by drilling. As a result, the printed wiring board 1c shown in FIG. 5F is completed. In the present embodiment, the second metal protective layer 22 to which the peeling film 25 is directly attached is removed by etching. Therefore, when the peeling film 25 is peeled off when the recess 2 is formed, even if the residue of the peeling film 25 remains on the second metal protective layer 22, the second metal protective layer 22 is removed by etching. It is considered that the residue of the peeling film 25 is also removed together with the second metal protective layer 22 during the removal. Since the surface of the clean metal protective layer 20 (in the case of FIG. 5F, the first metal protective layer 21) is exposed at the bottom surface of the concave portion 2, it is considered that the electronic component can be mounted well.

The printed wiring board of each embodiment is not limited to the structure illustrated in each drawing or the structure or material illustrated in this specification. The method for manufacturing the printed wiring board is not limited to the method described with reference to the drawings, and the conditions, order, etc. may be changed as appropriate. Some steps may be omitted or another step may be added depending on the structure of the printed wiring board actually manufactured.

1, 1a, 1b, 1c Printed wiring board 2 Recess 3 Buildup layer 5 Solder resist layer 10F First surface 10S Second surface 10 First insulating layer 10a Insulating layer 11 First conductor layer 11a Conductor layer 12 Via conductor 20 Metal protection Layer 21 First metal protective layer 22 Second metal protective layer 23 Third metal protective layer 25 Release film 30 Core substrate 30a Core substrate insulating layer 32 Second conductor layer 35 Through-hole conductor

Claims (5)

Providing an insulating layer having a first surface;
Forming a metal protective layer on the first surface;
On the metal protective layer, forming a buildup layer in which conductive layers and insulating layers are alternately laminated,
Forming a recess exposing the metal protective layer by removing a portion of the buildup layer;
Removing a portion of the metal protective layer exposed in the recess,
A method of manufacturing a printed wiring board having a recess including:
Forming the metal protective layer includes forming a first metal protective layer and forming a first metal protective layer from a material different from the material of the first metal protective layer so as to overlap the first metal protective layer in a plan view. Forming a two metal protective layer,
Removing a part of the metal protective layer includes exposing the first metal protective layer by removing the second metal protective layer with an etchant. The method for manufacturing a printed wiring board according to claim 1, wherein
Exposing the first metal protective layer may include removing the second metal protective layer using an etchant having an etching rate with respect to the second metal protective layer higher than that with respect to the first metal protective layer. Is included. The method for manufacturing a printed wiring board according to claim 1, wherein
Forming the metal protective layer may further include forming a third metal protective layer made of a material different from the material of the second metal protective layer so as to overlap the second metal protective layer in a plan view. Including,
Removing a portion of the metal protective layer further comprises exposing the second metal protective layer by removing the third metal protective layer with an etchant. The method of manufacturing a printed wiring board according to claim 3,
Exposing the second metal protection layer may include removing the third metal protection layer using an etchant having an etching rate with respect to the third metal protection layer higher than that with respect to the second metal protection layer. Is included. The method for manufacturing a printed wiring board according to claim 1, wherein
Forming the recess that exposes the metal protective layer includes performing laser processing or drill processing on the buildup layer.

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