JP5034289B2 - Multilayer printed wiring board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a multilayer printed wiring board and a method for manufacturing the same, and more particularly to a multilayer printed wiring board having a cavity (depression, recess) for mounting a semiconductor device and other electronic components and a method for manufacturing the same.

  Multi-layer prints with electronic components mounted that combine functions commonly used in multiple types of devices in order to meet various requirements such as miniaturization, thinning, weight reduction, high functionality, and compounding of various electronic devices Providing a wiring board as a module substrate has been performed. In addition, a multilayer printed wiring board at a stage before mounting electronic components is provided as a module substrate.

  Such a multilayer printed wiring board as a module substrate is required to be further reduced in size, thickness and density, and depending on how the module substrate is used, flexibility is required. For example, there is a demand for flexibility that can be bent and arranged in a narrow housing, and flexibility that can be bent repeatedly many times like a connecting portion of a folding mobile phone.

  As an example of such a multilayer printed wiring board, two rigid wiring boards are laminated on one side of a flexible wiring board through a glass-epoxy uncured prepreg, for example, and are integrated by heating and pressing. There has been proposed a rigid-flexible wiring board in which a conductive pattern of a rigid wiring board and a conductive pattern of a flexible wiring board are made conductive by an interlayer connection conductor such as a conductor bump (for example, Patent Document 1).

  On the other hand, in order to meet the demand for higher density, it has been proposed to use a rigid multilayer printed wiring board having a recess (cavity) for embedding a semiconductor device or other electronic components (for example, Patent Document 2). .

  A rigid multilayer printed wiring board having a cavity for embedding an electronic component is manufactured, for example, as follows. That is, an insulating adhesive sheet includes a lower printed wiring board having a circuit for electronic components to be mounted inside a cavity, and an upper printed wiring board having a window of a desired size for embedding the electronic components. Are laminated and integrated, and each wiring layer is made conductive by an interlayer connection conductor such as a conductor bump or a through hole, thereby forming a rigid multilayer printed wiring board with a cavity. Thereby, the part which opened the window becomes a cavity for embedding an electronic component.

  In Patent Document 2, as the upper and lower printed wiring boards, two or more layers of rigid wiring boards using a cured product of, for example, a glass-epoxy prepreg as an insulating layer are used. As a method of opening a window having a desired size on the upper printed wiring board, router processing, punching processing, drill processing, laser processing, or the like is used.

In the cavity of the multilayer printed wiring board with cavities manufactured in this way, electronic components are later mounted, and if necessary, other electronic components and other wiring boards are mounted thereon. Thus, a multilayer printed wiring board configured to be disposed on the module substrate or finally in the device is obtained.
JP-A-2005-322878 (especially paragraphs 0082 to 0084, FIGS. 33 to 36) JP-A-2005-070855

  However, after mounting electronic components after cleaning so that dust etc. do not remain in the cavity provided in the rigid wiring board by router processing etc., after mounting for a while, There was a problem that dust may be generated from the side wall of the cavity.

  If one of the cavity spaces is left open, it is not impossible to remove the dust. Therefore, even if dust is generated after the electronic component is mounted inside the cavity, it is not a serious problem. However, when dust is generated after the cavity space is closed by some member such as another wiring board or other electronic component, it is practically impossible to remove the dust, which is a problem.

  In particular, when a sensor or the like sensitive to fine particles around the component is mounted in the cavity as an electronic component, dust generation in the cavity becomes a serious problem because it causes a malfunction.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a multilayer printed wiring board having a cavity in which dust generation in the cavity is prevented and a method for manufacturing the same.

In order to achieve the above object, a multilayer printed wiring board according to the present invention is a multilayer printed wiring board provided with a cavity for mounting electronic components, and the inner wall surface of the cavity is coated with a synthetic resin. It is said. Resin coating the inner wall surface of the cavity is a synthetic resin which is leached from the impregnating resin of the prepreg constituting the multilayer printed wiring board.

  Here, the electronic component mounting cavity is a recess having an opening, a bottom surface, and an inner wall surface of a size necessary for mounting an electronic component such as a semiconductor device or a chip component therein. In order to mount an electronic component inside the cavity, it is necessary to place the electronic component on the bottom surface of the cavity, and a mounting terminal connected to the electrode terminal of the electronic component. The mounting terminal is not necessarily provided on the bottom surface of the cavity, and may be provided at a position where it can be connected to the electrode of the electronic component, such as near the cavity side wall of the uppermost layer of the multilayer printed wiring board.

  A black or dark dye or pigment may be added to the resin that coats the inner wall surface of the cavity. By doing so, since the light absorptance is increased, stray light can be prevented from entering the cavity.

  In the multilayer printed wiring board according to the present invention, an upper printed wiring board having a through hole serving as a cavity for mounting electronic components and a lower printed wiring board constituting a surface serving as a bottom of the cavity are laminated and integrated through a prepreg. The multilayer printed wiring board is characterized in that the inner wall surface of the cavity is coated with a synthetic resin leached from the impregnating resin of the prepreg.

  The lower printed wiring board and the upper printed wiring board have a substantially conical conductor bump formed in the connection land of the lower printed wiring board passing through the prepreg and the tip of the bump contacting the connection land of the upper printed wiring board. It is preferable that they are electrically connected by an interlayer connection conductor which is in contact and plastically deformed. By doing so, it is possible to reduce the number of processes as compared to forming through holes and connecting between layers, and it is possible to obtain an effect that the mounting area is not reduced.

  It is preferable to use a rigid wiring board as the upper printed wiring board with a through hole serving as a cavity for mounting electronic components, and a flexible wiring board as the lower printed wiring board constituting the surface to be the bottom of the cavity. . By doing so, it is possible to provide a module substrate having a cavity for mounting electronic components and having both rigidity and flexibility.

  The method for producing a multilayer printed wiring board according to the present invention is a method for producing a multilayer printed wiring board provided with a cavity for mounting an electronic component, wherein a conductor pattern is provided on at least one outer layer surface. An uncured prepreg having a lower printed wiring board in which conductor bumps serving as interlayer connection conductors are formed at predetermined positions and containing a resin having fluidity on the conductive bump forming surface of the lower printed wiring board The lower end of the conductor bump is exposed through the uncured prepreg, and the lower printed wiring board is exposed and connected to the conductor pattern and the conductor pattern on at least one outer layer surface. An upper printed wiring board on which connection lands corresponding to the conductor bumps of the lower printed wiring board are formed is prepared, and the cap is placed at a predetermined position on the upper printed wiring board. A step of making a through-hole serving as a tee, and the upper printed wiring board and the lower printed wiring board are laminated with the conductor bumps and the connection lands facing each other, heated and pressed, and exposed through A synthetic resin in which the tip of the conductive bump is brought into contact with the connecting land of the other printed wiring board and plastically deformed to be electrically connected and mechanically integrated, and the inner wall surface of the cavity is leached from the impregnating resin of the prepreg And a coating step.

  That is, in the method for producing a multilayer printed wiring board according to the present invention, the adhesiveness interposed between the upper printed wiring board provided with holes serving as cavities for mounting electronic components and the lower printed wiring board constituting the cavity bottom surface. As the insulating sheet, an uncured prepreg containing a fluid resin is used. Therefore, the upper printed wiring board and the lower printed wiring board are laminated and integrated through the prepreg, and at the same time, the impregnating resin of the prepreg obtains fluidity to coat the cavity inner wall surface. Therefore, it is possible to provide a multilayer printed wiring board having a cavity that prevents dust generation in the cavity without increasing the number of manufacturing steps.

  ADVANTAGE OF THE INVENTION According to this invention, the multilayer printed wiring board which has the cavity which prevented the dust generation in a cavity, and its manufacturing method can be provided.

  That is, the cavity provided in the multilayer printed wiring board according to the present invention has an inner wall surface coated with a synthetic resin. Therefore, even if dust is generated in the insulating layer of the multilayer printed wiring board, the dust does not enter the cavity. Therefore, dust generation in the cavity can be prevented.

  Thereby, even if the electronic component mounted inside the cavity is a sensor sensitive to dust or the like around the component, it is possible to prevent malfunction due to dust generation.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, in principle, the same components are denoted by the same reference numerals, and description thereof is omitted. Although embodiments of the present invention are described based on the drawings, the drawings are provided for illustration, and the present invention is not limited to the drawings.

[First Embodiment]
First, an example of a multilayer printed wiring board 100 with a cavity according to the first embodiment and a method for manufacturing the same will be described with reference to FIGS.

  FIG. 1 is a plan view of the multilayer printed wiring board 100 with cavities as viewed from the cavity opening side. FIG. 2 is a cross-sectional view schematically showing a cross section taken along line AA of FIG. 1 with emphasis on the thickness direction compared to the width direction. In FIG. 2, the two wavy lines shown in the lower right of the drawing indicate that the portion between the wavy lines is omitted.

  As shown in FIGS. 1 and 2, the multilayer printed wiring board 100 includes a cavity 1 having an opening for mounting a desired electronic component such as an IC chip or a sensor therein. The cavity 1 has such a size and depth that a desired electronic component can be placed and embedded in the cavity 1 in a desired direction. A mounting terminal 2 for electrically connecting an electronic component placed inside the cavity is exposed at the bottom surface of the cavity 1.

  The inner wall surface 1a of the cavity 1 is coated with resin. Thereby, the fiber of the inner wall of the cavity 1 can be fixed, and dust generation can be prevented. That is, even if the cavity 1 is formed by cutting an insulating substrate containing a material that easily generates dust, such as glass fiber or aramid fiber, by router processing, laser processing, or the like, it is caused by the material included in the insulating substrate. It is possible to prevent dust from entering the cavity from the inner wall surface of the cavity. Therefore, even if the electronic component embedded in the cavity is various sensors that are sensitive to dust around the component, it is possible to prevent malfunction caused by dust generation in the cavity.

  As shown in FIGS. 1 and 2, the multilayer printed wiring board 100 has six wiring layers on which conductor patterns are formed. The wiring layers 12, 22, and 32 are electrically connected by interlayer connection conductors 13, 23, and 33, respectively. In the outermost layer of the multilayer printed wiring board 100, a part of the conductor pattern is exposed as a mounting terminal 3 for later mounting various electronic components, and the other part is covered with a protective film 8 such as a solder resist. ing. Note that the configuration of the conductor pattern including the mounting terminal 2 exposed at the bottom of the cavity 1 and the mounting terminal 3 exposed at the outermost layer is arbitrary and is not limited to the illustrated one. Further, the wiring layers need not be six layers and may be any number of layers. However, the number of layers is three or more because of demands for miniaturization and high density.

  In order to mount an electronic component inside the cavity, a mounting terminal for electrical connection with the electrode of the electronic component is required. The mounting terminals are preferably provided on the bottom surface of the cavity as indicated by reference numeral 2 shown in FIGS. 1 and 2, but need not be the bottom surface of the cavity. It should just be provided in the location which can be connected with the electrode of electronic components, such as a peripheral part. On the other hand, as another embodiment, the rigid wiring board 30 may not be provided, and the end of the lower wiring board 20 may simply be a connection terminal.

  As shown in FIGS. 1 and 2, the upper part of the multilayer printed wiring board 100 is provided with a four-layer rigid wiring board 10 provided with an opening serving as a cavity 1 and an opening disposed apart from the four-layer rigid wiring board 10. The four-layer rigid wiring board 30 has a small area. The lower part of the multilayer printed wiring board 100 is entirely composed of a double-sided flexible wiring board 20. The rigid wiring board 10 and the rigid wiring board 30 are electrically connected by a conductor pattern 22 formed on the double-sided flexible wiring board 20. In this example, the rigid wiring board 30 has a smaller area than the rigid wiring board 10, but the rigid wiring board 30 may have the same area as the rigid wiring board 10, and the rigid wiring board 30 has a cavity. Of course, a through hole may be formed.

  The interlayer insulating layer 11 of the rigid wiring board 10 and the interlayer insulating layer 31 of the rigid wiring board 30 are hard (rigid) insulating layers, for example, non-woven fabric of organic fibers such as glass fiber and aramid fiber, paper, and the like A prepreg impregnated with an uncured epoxy resin, polyimide resin, bismaleimide resin, phenol resin, etc. (eg glass-epoxy prepreg) is laminated on the base material and cured by heating and pressurizing to a temperature higher than the glass transition temperature. It is a thing.

  The interlayer insulating layer 21 of the flexible wiring board 20 is a flexible (flexible) insulating layer having flexibility, for example, a prepreg having flexibility even after curing while using a liquid crystal polymer, polyimide resin, or glass cloth as a base material. Etc.

  The rigid wiring board 10 and the rigid wiring board 30 that are the upper printed wiring boards and the flexible wiring board 20 that is the lower printed wiring board are stacked via the insulating layer 7 and integrated by heating and pressing. The connection land 5 which is a part of the wiring layer 22 on the side of the flexible wiring board 20 connected to the rigid wiring board 10 and the connection land which is a part of the wiring layer 12 of the rigid wiring board 10 on the side connected to the flexible wiring board 20. The land 4 is electrically connected by an interlayer connection conductor 6. The interlayer connection conductor 6 is formed by, for example, inserting a conductor bump formed by screen-printing a conductive paste on the connection land 5 on the flexible substrate side into an uncured prepreg serving as an insulating layer 7. It is made to abut against the opposing connection land 4 and is plastically deformed and solidified.

  As described above, the multilayer printed wiring board 100 includes the cavity 1 that is a recess for mounting an IC chip, a sensor, and other electronic components, and is also a substrate having both rigidity and flexibility. Moreover, since this multilayer printed wiring board 100 does not use through holes, it is easy to increase the density and the manufacturing process can be simplified. The inner wall surface 1a of the cavity 1 is coated with resin, and dust can be prevented from entering the cavity from the inner wall surface of the cavity. Therefore, for example, it is suitable as a module substrate used in a sensor module or a camera module of an electronic device that is required to be reduced in size, reduced in thickness, and increased in density and has a connecting portion that is bent repeatedly.

  3 to 8 are schematic cross-sectional views for explaining an example of the optimum embodiment as a method for manufacturing the multilayer printed wiring board 100. In the drawing, the right side or the left side of the portion indicated by the wavy line indicates that it is omitted.

  First, as shown in FIG. 3, a rigid wiring board 10 without a window is prepared as an upper printed wiring board provided with a window (through hole) serving as a cavity.

  The configuration of the rigid wiring board 10 takes into consideration the necessary circuits, the thickness and size necessary for embedding electronic components, the thickness (thinness) and size required for the module substrate, and other design matters. As appropriate. Any number of wiring layers may be used, but a wiring layer made of a conductor pattern is formed in advance on the inner layer and the outer layer, and is made conductive by the interlayer connection conductor.

The rigid wiring board 10 can be manufactured by a well-known material and method as a rigid printed wiring board having a plurality of wiring layers, and the material and manufacturing method are not particularly limited. For example, an interlayer connection method such as a known through hole or laser via hole may be used. Here, as an example, a rigid wiring board 10 having a four-layer conductor pattern schematically shown in FIG. 3 is manufactured by a manufacturing method known as Japanese Patent Application Laid-Open No. 06-342977 called B ² it (registered trademark). did.

  In FIG. 3, reference numeral 11 denotes a hard insulating layer that is a cured product of a glass-epoxy prepreg having a thickness of 40 to 60 μm, and reference numeral 12 denotes an electrolytic copper foil having a thickness of 18 μm that is patterned using a well-known photolithography technique. It is the conductor pattern formed by. Reference numeral 13 denotes a conductor having a substantially conical shape (for example, a bottom diameter of 0.15 mm and a height of 60 to 150 μm) made of a cured product of a polymer-type silver-based conductive paste formed on an electrolytic copper foil or a conductor pattern. This is an interlayer connection conductor that is solidified by being plastically deformed into a substantially frustoconical shape by inserting a bump into an uncured prepreg, contacting the conductor pattern 12, and applying pressure and heating. Reference numeral 8 denotes a protective film such as a solder resist.

  As shown in FIG. 2 and FIG. 3, the side (the upper side in the drawing) of the rigid wiring board 10 as the multilayer printed wiring board 100 leaves a conductor pattern region to be the mounting terminal 3, and a protective film such as a solder resist. 8 is covered. In addition, a connection land 4 is formed at a predetermined position on the side (lower side of the drawing) of the rigid wiring board 10 connected to the flexible wiring board 20 so as to be electrically connected to the flexible wiring board 20 through an insulating layer. A protective film 8 such as a resist is not formed. A conductor pattern or the like is not formed in a region where the through hole 14 serving as the cavity 1 for embedding the electronic component is formed.

  In this example, the interlayer connection conductor 13 has a substantially conical conductor bump formed at a predetermined position of the conductor pattern 12 as described above in contact with the opposing conductor pattern through the rigid insulating layer 11. It is composed of one that has been solidified by plastic deformation. As a result, there are advantages in that the conductor pattern can be made finer and the manufacturing process can be simplified as compared with the case of using an interlayer connection method in which a hole such as a through hole or a laser via hole is formed and the inner wall is plated.

  Next, as shown in FIG. 4, a window (through hole) 14 penetrating the rigid wiring board 10 is formed in the rigid wiring board 10 in a desired size and shape for forming the cavity 1 for mounting electronic components. I can make it. The window 14 can be opened by router processing, punching processing, drill processing, laser processing, or the like. It is preferable that the processing method is less likely to generate dust. Here, as an example, the window 14 is opened in the rigid wiring board 10 by router processing. After drilling, it was cleaned by, for example, a dust removal roll or water washing so that there was no dust in the vicinity of the window 14 of the rigid wiring board 10.

  On the other hand, as shown in FIG. 5, the flexible wiring board 20 laminated | stacked on the lower side of the rigid wiring boards 10 and 30 is prepared. Here, a flexible wiring board 20 having the same width as the rigid wiring boards 10 and 30 and a length sufficient to connect the rigid wiring board 10 and the rigid wiring board 30 was prepared. By doing so, since the back surface side of the multilayer printed wiring board 100 shown in FIG. 1 becomes the flexible wiring board 20 entirely, it becomes substantially flat. Therefore, the flexible wiring board 20 and the rigid wiring boards 10 and 30 are integrally laminated. It becomes easy.

  The configuration of the flexible printed circuit board as the lower printed circuit board that constitutes the bottom of the cavity 1 takes into account the necessary circuit, thickness (thinness) and size required for the module substrate, and other design matters. As appropriate. The number of wiring layers of the lower printed wiring board may be any number, but it is necessary to form conductor patterns on the inner layer and the outer layer in advance on the lower printed wiring board. When a plurality of wiring layers are used, each wiring layer is electrically connected in advance by an interlayer connection conductor.

The flexible wiring board 20 constituting the bottom of the cavity 1 can be manufactured by a known material or manufacturing method, and the material or manufacturing method is not particularly limited. Here, as an example, a flexible wiring board 20 having a two-layer conductor pattern schematically shown in FIG. 5 is manufactured by a manufacturing method known as Japanese Patent Application Laid-Open No. 06-342977 called B ² it (registered trademark). did.

  In FIG. 5, the code | symbol 21 is a flexible insulating layer which consists of the hardened | cured material of the prepreg for flexible substrates which has a softness | flexibility rather than the prepreg for normal rigid substrates after hardening, The thickness is 40-60 micrometers. . Reference numeral 22 denotes a conductor pattern formed by patterning an electrolytic copper foil having a thickness of 18 μm. Reference numeral 23 denotes a conductor having a substantially conical shape (for example, a bottom diameter of 0.15 mm and a height of 60 to 150 μm) made of a cured product of a polymer-type silver-based conductive paste formed on an electrolytic copper foil or a conductor pattern. It is an interlayer connection conductor that is solidified by being plastically deformed into a substantially frustoconical shape by inserting bumps into a flexible insulating layer 21, contacting the conductor pattern 22, and applying pressure and heating. Reference numeral 8 denotes a protective film such as a solder resist.

  As shown in FIGS. 2 and 5, the side (lower side of the drawing) of the flexible printed circuit board 20 that is the outer layer of the multilayer printed wiring board 100 leaves a conductor pattern region that becomes the mounting terminals 3 and protects the solder resist and the like. Covered with a membrane 8. Further, a connection land 5 is formed at a predetermined position on the side of the flexible wiring board 20 connected to the rigid wiring board 10 (upper side in the drawing) so as to be electrically connected to the rigid wiring board 10 through an insulating layer. The protective film 8 such as is not formed.

  Next, in order to obtain an interlayer connection conductor between the flexible wiring board 20 and the rigid wiring boards 10 and 30, a substantially conical shape is formed at a predetermined position (connection land 5) of the conductor pattern 22 on one surface of the prepared double-sided flexible wiring board 20. A conductor bump 26 having a shape was formed. That is, a metal mask having a 0.15 mm diameter hole is prepared at a predetermined position of a metal plate made of a material such as stainless steel or aluminum alloy having a thickness of 150 μm, and this metal mask is positioned on one side of the flexible wiring board 20. Then, the conductive paste is printed, and after the printed conductive paste is dried, the printing is repeated by the method of printing again at the same position, and the necessary number of substantially conical conductor bumps 26 having a height of 60 to 150 μm are collected. Formed. Here, the diameter and height of the bottom surface of the conductor bump 26 are not limited to this example, and are appropriately determined in consideration of the wiring interval and the thickness of the insulating layer that penetrates.

  On the other hand, an uncured prepreg 27 having a thickness of 40 to 60 μm was prepared in order to obtain an adhesive insulating layer 7 between the rigid wiring boards 10 and 30 and the flexible wiring board 20. The prepreg 27 may be prepared in a size and a shape corresponding to the region of the flexible substrate 20 laminated with the rigid wiring board 10 and the region laminated with the rigid wiring board 10. Therefore, similarly to the rigid wiring board 10, a window (through hole) was previously formed in the prepreg 27 by router processing or the like.

  Here, the prepreg 27 is, for example, a film-like material obtained by impregnating a non-woven synthetic resin having electrical insulation properties and heat-sealability into a base material such as glass fiber, organic fiber non-woven fabric such as aramid fiber, and paper. It is a sheet. As the prepreg 27, a non-flow type glass-epoxy prepreg impregnated with a non-flowable resin can be used as in the case of an insulating layer of a normal rigid substrate, but it contains a synthetic resin having flowability. It is preferable to use a flow type. By using a prepreg 27 containing a fluid synthetic resin, the inner wall surface of the cavity 1 can be coated with the synthetic resin.

  That is, as the uncured prepreg 27 that is laminated and interposed between the rigid wiring board 10 and the flexible wiring board 20, a material containing a fluid synthetic resin is used, and these are aligned and laminated. When heated and pressurized, the impregnating resin of the prepreg 27 obtains fluidity, the rigid wiring board 10 and the flexible wiring board 20 are thermocompression bonded via the prepreg 27, and the inner wall surface 1 a of the cavity 1 is the prepreg 27. The synthetic resin leached from the impregnated resin is integrally coated. The uncured prepreg 27 is thermally cured to form the insulating layer 7. Therefore, the multilayer printed wiring board 100 with the cavity whose inner wall surface is integrally coated with the same resin as that contained in the insulating layer 7 is obtained.

  That is, since the impregnating resin of the prepreg 27 has fluidity, the prepreg 27 includes a rigid wiring board 10 having a through-hole serving as a cavity 1 for mounting an electronic component and a flexible wiring board 20 constituting the bottom surface of the cavity 1. In addition to being an insulating adhesive sheet laminated in between, it also serves as a material for coating the inner wall surface 1 a of the cavity 1.

  Here, that the impregnating resin has fluidity means that the resin flowability is 0.5 to 65% at the molding processing temperature, desirably 20 to 50%. As a specific example, when the thickness of the prepreg is 100 μm, the resin flowability is 43 ± 7%, and when the thickness is 60 μm, the resin flowability is about 33 ± 7%. Model number R1551). With this level of fluidity, the rigid wiring board 10 and the flexible wiring board 20 can be laminated and integrated, and the inner wall surface 1a of the cavity 1 can be coated, so the lamination and coating are performed in separate steps. Compared to this, the manufacturing process can be simplified and the material can be saved.

In this case, the resin flowability is a value measured and calculated as follows. That is, first, a test piece is cut into a width of 100 ± 0.3 mm, the length is adjusted so that the total amount is about 20 g, and weighed, and this value is defined as a. Next, the test piece is placed in a test press adjusted to 170 ± 3 ° C. in advance, pressurized for 20 minutes at a pressure of 14 ± 1.4 kg / cm ² , the resin that has flowed out is removed, and the test piece is weighed again. Let the value be b. Then, resin flowability (%) is calculated by the calculation formula [((ab) / a) * 100].

  Here, it is preferable to add a color dye or pigment having a high light absorption rate to the prepreg 27 serving as a material for coating the inner wall surface 1 a of the cavity 1. By doing so, the inner wall surface 1a of the cavity 1 is coated with the color and the light absorption rate is increased. Therefore, even when the glass fiber is used as the base material of the insulating layer constituting the multilayer printed wiring board 100, the cavity It is possible to prevent stray light from entering 1. Here, black is preferable as a color having a high light absorption rate, but may be a dark color that is not black. Examples of the black or dark prepreg include model number GHPL-832HS manufactured by Mitsubishi Gas Chemical Company.

  That is, the prepreg usually used as the insulating layer of the multilayer printed wiring board is colorless or cream-colored and contains glass fibers. Therefore, conventionally, when the embedded electronic component is an electronic component that operates based on the light receiving element or the amount of light received, such as a CCD (Charge Coupled Devices) or a photo sensor (photo sensor), it leaks from the side wall of the cavity. There was a problem that it sometimes malfunctioned by stray light that entered the cavity. As described above, this problem was solved by adding a dye or a pigment having a high light absorption rate to the prepreg serving as a coating material for the inner wall surface of the cavity.

  Next, as shown in FIG. 6, the prepreg 27 is brought into contact with the leading end side of the conductor bump 26, and placed between, for example, a hot plate maintained at 100 ° C. via an aluminum foil and a rubber sheet, and 1 MPa at 1 minute. By applying heat and pressure to the extent, the tip of the conductor bump 26 was inserted into the prepreg 27, and the flexible wiring board 20 in which the tip of the conductor bump 26 protruded from the prepreg 27 was obtained.

  Next, as shown in FIG. 7, the flexible wiring board 20 with the front end of the conductor bump 26 protruding from the prepreg 27 is placed on the flat holding plate 61 of a sufficiently large size, and the front end side of the conductor bump 26 is And place it. On top of that, the rigid wiring board 10 with the window 14 opened is aligned and positioned so that the conductor bumps 26 and the connection lands 4 of the rigid wiring board 10 face each other. On top of that, a first pressing plate 62 having a size corresponding to a position corresponding to the window 14 formed on the rigid wiring board 10 is laminated and disposed. On top of that, a conformal material 51 made of a low melting point resin film in which a release film 52 is laminated on the top and bottom is laminated. On the uppermost layer, a flat pressing plate 63 that is not opened is laminated.

  Here, the conformal material 51 has a resin flow path so that the resin impregnated in the prepreg 27 flows along the shape of the inner wall surface of the window 14 to reliably coat the inner wall surface of the cavity 1. It is for controlling the flow rate of the formed resin. As the conformal material 51, a resin having a melting point lower than the glass transition temperature of the prepreg 27, for example, a film made of low melting point polyethylene having a melting point of about 90 ° C. can be used.

  As the pressing plates 61, 62, 63, a metal plate or a heat-resistant resin plate with little size and deformation, such as a stainless steel plate, a brass plate, a polyimide resin plate (sheet), a polytetrafluoroethylene resin plate (sheet), or the like is used. The

  At this time, it is preferable that the window (through hole) provided in the holding plate 62 be slightly smaller than the window 14 provided in the rigid wiring board 10 as shown in FIG. For example, the through hole in the holding plate 62 is formed smaller than the window (through hole) 14 formed in the upper rigid wiring board 10, and when the through holes are overlapped, the through hole and the upper side of the holding plate 62 are overlapped. It is preferable that the difference between the edge portions of the through hole 14 of the rigid wiring board 10 is slightly larger than the coating thickness of the cavity inner wall surface 1a. By doing so, it is possible to coat with an appropriate thickness along the cavity inner wall surface 1a and to align the position of the upper end surface of the resin cavity inner wall.

  And it arrange | positions between the hot plates hold | maintained to the temperature which is more than melting | fusing point of this conformal material 51, and less than the temperature in which the impregnation resin of the prepreg 27 becomes a plastic state, for example, 95 +/- 5 degreeC, Press. Then, the conformal material 51 obtains fluidity, and falls by its own weight together with the release film 52 laminated on the lower side through a through hole formed in the holding plate 62, and as shown in FIG. It is deformed into a shape generally along the inner shape of the recess (formed by the through hole 14 and the upper surface of the flexible wiring board 20 constituting the bottom surface of the cavity 1).

  At this time, as shown in FIG. 7 and FIG. 8, there is little difference between the edges of the window of the holding plate 62 and the window 14 of the rigid wiring board 10, so that the conformal material is formed along the inner wall surface of the cavity 1. A gap is created between This gap becomes a resin flow path that coats the inner wall surface of the cavity 1.

  Thereafter, the temperature is further raised and heated and pressurized. Then, as shown in FIG. 8, the tips of the conductor bumps 26 protruding from the prepreg 27 abut against the connecting lands 4 of the rigid wiring board 10 facing each other, and the tips are plastically deformed into a truncated cone shape. The interlayer connection conductor 6 that directly connects the connection land 4 and the connection land 5 of the flexible wiring board 20 is obtained, and the impregnated resin of the prepreg 27 obtains fluidity and deforms along the inner wall surface of the cavity 1. It leaches into the gap with the material 51, and the inner wall surface of the cavity 1 is coated with this resin.

  And after hardening the prepreg 27, after cooling, the press plates 61 and 63, the deformed conformal material 51, the release film 52 laminated | stacked on the both surfaces, and the press plate 62 which opened the through-hole are used. It peeled and the multilayer printed wiring board 100 with a cavity shown in FIG.1 and FIG.2 was obtained.

  The multilayer printed wiring board 100 with a cavity shown in FIGS. 1 and 2 is manufactured as described above.

  FIG. 9 and FIG. 10 are schematic cross-sectional views showing, in an enlarged manner, modified examples in the vicinity of the side wall on one side of the cavity 1 of the multilayer printed wiring board 100 with a cavity according to the present embodiment. 9 and 10, the details of the conductor pattern, the interlayer connection portion, and the like are omitted, but reference numeral 10 indicates that the rigid insulating layer 11 and the wiring layer 12 made of the conductor pattern are alternately stacked and are electrically connected. It is also a rigid wiring board, and is also an upper printed wiring board provided with a through hole serving as a cavity 1. Reference numeral 20 denotes a double-sided flexible wiring board similar to that described with reference to FIGS. 5 and 6, and also a lower printed wiring board. Similar to FIGS. 2 and 8, there are similar cavity side walls on the right side of the drawing in a symmetrical manner, but the illustration is omitted in FIGS. 9 and 10.

  As shown in FIGS. 9 and 10, an insulating support film 68 is disposed near the side wall of the bottom surface of the cavity 1 of the lower printed wiring board 20 with a part interposed below the upper printed wiring board 10. You may set up. By doing so, when the upper printed wiring board 10 provided with the through-hole 14 serving as the cavity 1 and the lower printed wiring board 20 are laminated via the prepreg 27 and heated and pressed, the rigid wiring board 10 It is possible to prevent the prepreg 27 stacked on the lower side in the vicinity of the cavity side wall from being crushed and tilting the portion in the vicinity of the cavity side wall. That is, when the rigid wiring board 10 or the prepreg 27 laminated between the rigid wiring board 10 and the flexible wiring board 20 becomes thin, the pressure is applied to the rigid wiring board 10 and the prepreg in the vicinity of the cavity side wall when heated and pressurized. 27 may be crushed and tilted. When inclined, the conductor pattern 12 below the side wall of the rigid wiring board 10 and the conductor pattern (not shown) formed on the upper surface of the flexible wiring board 20 are short-circuited, or the flatness of the uppermost layer of the rigid wiring board 10 is lost. There was a problem. As shown in FIGS. 9 and 10, the problem can be solved by disposing an insulating support film 68.

  As the insulating support film 68, a solder resist can be used. As described with reference to FIGS. 5 and 6, a protective film 8 such as a solder resist is partially disposed on the outermost layer of the flexible wiring board 20. At that time, a solder resist as an insulating support film 68 is disposed in the vicinity of the position to be the lower portion of the cavity side wall so as to straddle the region overlapping the lower side of the rigid wiring board 10 and the region exposed as the bottom surface of the cavity. It is good to install. By doing so, the insulating support film 68 can be disposed without increasing the number of manufacturing steps, and the effect of preventing the inclination of the portion near the cavity side wall can be obtained. Instead of the solder resist 8, a photoresist (not shown) that is usually used in the manufacturing process of the flexible wiring board 20 may be used.

  As shown in FIG. 10, the insulating support film 68 may be disposed such that the portion inside the cavity 1 is higher than the portion interposed below the upper printed wiring board 10. By doing so, the flow of resin impregnated in the prepreg 27 into the cavity 1 can be stopped and the flow rate of the resin can be controlled. Further, between the end of the insulating support film 68 on the inner side of the cavity and the protective film 8 such as a solder resist disposed on the inner side, a gap 9 (no solder resist or conductor pattern is provided, It is preferable to provide a slight portion of the lower printed wiring board 20 where the insulating layer 21 is exposed or a portion where only the conductor pattern is formed and lower than the insulating support film 68. By doing so, when heated and pressurized, the conformal material 51 (not shown) obtains fluidity, enters the gap, and blocks the flow of the resin leached inside the cavity 1, so that more reliably, The flow rate of the resin can be controlled. In order to arrange the insulating support film 68 so that the portion inside the cavity 1 is raised, a dummy conductor pattern 69 is preferably formed below the insulating support film 68 as shown in FIG. That is, when the conductor pattern is formed on the outermost layer of the flexible wiring board 20, the dummy conductor pattern 69 is preferably provided at a position near the side wall of the cavity bottom surface. Then, an insulating support film 68 may be disposed thereon with a solder resist. By doing so, it is possible to prevent the inclination in the vicinity of the side wall of the cavity 1 without increasing the number of manufacturing steps, and to control the amount of resin leached inside the cavity 1.

  In the present invention, the method for forming the cavity for embedding the electronic component and the method for coating the inner wall surface of the cavity are not limited to the above methods. For example, a cavity having an opening for embedding an electronic component can be formed by countersinking the upper layer portion of a multilayer printed wiring board, and the inner wall surface can be coated by separately applying a coating resin after the cavity is formed. I can. However, the upper printed wiring board with a through hole serving as a cavity and the lower printed wiring board constituting the bottom surface of the cavity are not stacked via a prepreg, but a cavity is formed by countersinking the upper layer portion. In some cases, it is necessary to take care not to damage the wiring portion formed on the bottom surface of the cavity, which is difficult. Further, when coating the inner wall surface by separately applying a coating resin after forming the cavity, it is difficult to uniformly apply the resin along the vertical inner wall surface, and a separate process is required. According to the manufacturing method of the multilayer printed wiring board demonstrated in the said embodiment, these difficulties are avoided. Therefore, the method for producing a multilayer printed wiring board described in the above embodiment is optimal as a method for producing a multilayer printed wiring board with a cavity in which the cavity inner wall surface is coated with a resin.

  In addition, as the conductor bumps serving as the interlayer connection conductor, for example, conductive powder such as silver, gold, copper, solder powder, alloy powder or composite (mixed) metal powder, and polycarbonate resin, polysulfone resin, polyester resin, It can be composed of a paste-like conductive composition (conductive paste) prepared by mixing a binder component such as phenoxy resin, phenol resin, or polyimide resin, or a conductive metal. When the conductive bump is formed of a conductive composition, the bump having a high aspect ratio can be formed by, for example, a printing method using a relatively thick metal mask. As means for forming a conductive bump with a conductive metal, (a) a fine metal soul having a certain shape or size is spread on a conductive metal layer surface on which an adhesive layer has been provided in advance, and is selectively fixed. (At this time, a mask may be arranged), (b) A plating resist is printed and patterned on the surface of the electrolytic copper foil, and copper, tin, gold, silver, solder, etc. are plated to selectively form a minute metal. Forming columns (bumps); (c) applying and patterning a solder resist on the surface of the conductive metal layer; and dipping in a solder bath to selectively form minute metal columns (bumps); (d) metal plate A part of the film is covered with a resist and etched to form a fine metal bump. Here, the fine metal soul or the fine metal pillar corresponding to the conductor bump may have a multilayer structure or a multilayer shell structure in which different metals are combined. For example, copper may be cored and the surface may be coated with a gold or silver layer to provide oxidation resistance, or copper may be cored and the surface may be coated with a solder layer to provide solder jointability. In the present invention, when the conductive bump is formed of a conductive composition, the process can be further simplified as compared with the case where the conductive bump is formed by means such as plating, which is effective in terms of cost reduction.

  In the present embodiment, when the rigid wiring board 10 and the flexible wiring board 20 are laminated and integrated via the prepreg 27, the conductor bumps 26 to be the interlayer connection conductors 6 are rigidly integrated as described with reference to FIG. It is formed not on the wiring board 10 side but on the flexible wiring board 20 side. The conductor bump 26 is made of a substantially conical conductive paste formed on the connection land 5 on the flexible wiring board 20 side. That is, as shown in FIGS. 7 and 8, the bottom surface side of the conductor bump 26 that becomes the interlayer connection conductor 6 faces the flexible wiring board 20 side, and the tip side faces the rigid wiring board 10 side. Both sides of the conductor bumps 26 serving as interlayer connection conductors are connection lands 4 and 5 formed of copper foil. The insulating substrate on which the connection lands 4 and 5 (conductor patterns 11 and 12) are formed is The rigid wiring board 10 is harder than the flexible wiring board 20. Therefore, the conductor bump 26 formed on the flexible wiring board 20 side is plastically deformed by contacting the tip of the conductor bump 26 with the rigid wiring board 10 side, so that the flexible wiring board 20 side is placed as shown in FIGS. The large-diameter and rigid wiring board 10 side is a conductor bump 6 which is a small-diameter, generally frustoconical interlayer connection conductor. In this way, the conductor bumps 26 are formed on the connection lands 5 on the flexible wiring board 20 side, and the conductor bumps 26 are brought into contact with the connection lands 4 on the rigid wiring board 10 side to be plastically deformed. Connected. That is, the relatively soft flexible wiring board side connection land has a large-diameter base directly formed and the small-diameter tip of the conductor bump is pressed against the rigid wiring board side, so that the flexible wiring board side is deformed by stress. On the contrary, the tip end portion of the conductor bump contacting the rigid wiring board side is easily plastically deformed to form a truncated cone-shaped interlayer connection conductor. Therefore, the effect that the connection reliability of a rigid wiring board and a flexible wiring board increases is acquired.

  Contrary to the present embodiment, conductor bumps 26 may be formed on the rigid wiring board 10 side to be laminated and integrated. However, it is preferable to form the conductor bumps 26 on the flexible wiring board 20 side for the above reasons.

  In the present embodiment, as an upper printed wiring board, an example in which two rigid wiring boards are separated from each other and stacked on the flexible wiring board 20 constituting the cavity bottom portion is shown. However, the present invention is not limited to this, and one rigid wiring board may be used as the upper printed wiring board. That is, it may be a multilayer rigid-flexible wiring board that does not include the rigid wiring board 30 shown on the right side of the drawing. Further, the number of wiring layers is not limited to this, and it is needless to say that the present invention can be similarly implemented even with other numbers of layers.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIGS. In principle, the same reference numerals are given to portions common to the first embodiment, and description thereof is omitted.

  11 is a plan view of the multilayer printed wiring board 200 according to the second embodiment as viewed from the cavity 1 side, and FIG. 12 is a cross-sectional view schematically showing a vertical cross section along the line BB in FIG. It is.

  As shown in FIG. 11 and FIG. 12, this multilayer printed wiring board 200 is not provided with a four-layer rigid wiring board 210, which is an upper printed wiring board provided with a cavity 1 having an opening for embedding electronic components, and no opening. This is an eight-layer rigid printed wiring board with a cavity in which a lower-layer printed wiring board that is a four-layer rigid wiring board 220 is laminated and integrated with an insulating layer 7 interposed therebetween. The upper printed wiring board 210 and the lower printed wiring board 220 have the same outer shape.

  This multilayer printed wiring board 200 is also manufactured in the same manner as in the first embodiment. There is a difference that the lower printed wiring board 220 constituting the bottom surface of the cavity 1 is a rigid wiring board, and that the upper printed wiring board 210 and the lower printed wiring board 220 have the same outer shape. The configuration is the same as that of the first embodiment, and the manufacturing method is also the same.

  That is, the multilayer printed wiring board 200 includes a rigid wiring board 210 that is an upper printed wiring board having a through-hole serving as a cavity 1, and a rigid wiring board 220 that is a lower printed wiring board constituting the bottom surface of the cavity 1. Are laminated and integrated by an insulating layer 7 which is a cured product of the prepreg 27 containing a resin having fluidity. The inner wall surface 1 a of the cavity 1 is integrally coated with the insulating layer 7 by an impregnating resin of a prepreg 27 that has obtained fluidity by heating and pressing.

  The connection land 4 that is a part of the conductor pattern at the bottom layer of the rigid wiring board 210 and the connection land 5 that is a part of the conductor pattern at the top layer of the rigid wiring board 220 are formed on the connection land 5. The insulating layer 7 is inserted through pressure heating, and the tip is brought into contact with the connection land 4 and is electrically connected by a conductor bump (interlayer connection conductor) 6 which is plastically deformed.

  In this embodiment, since both the wiring boards are rigid boards, the substantially conical conductor bumps to be the interlayer connection conductor 6 may be formed on the opposite side (connection land 4 side).

  Thus, the multilayer printed wiring board may be a laminate of rigid wiring boards. In this case, the effect of a wiring board having both rigidity and flexibility, which is obtained with a rigid-flexible wiring board, cannot be obtained. Still, since the inner wall surface 1a of the cavity 1 is coated with resin, dust caused by the material constituting the cavity side wall is not mixed into the cavity 1, and the effect of preventing dust generation can be obtained. Moreover, since it is not necessary to perform coating of the inner wall surface 1a of the cavity 1 in a separate process, an effect that the process can be simplified is obtained.

  Similarly to the first embodiment, a dye or a high light absorption rate is applied to the prepreg which is a coating material for the insulating layer 7 and the inner wall surface 1a of the cavity 1 laminated between the rigid wiring boards 210 and 220. A pigment, that is, a black or dark dye or pigment may be added and mixed. By doing so, since the cavity inner wall surface 1a is coated in black or dark color, even when the glass fiber is used as the base material of the insulating layer constituting the multilayer printed wiring board 200, the light passing through the glass fiber is Since it is almost absorbed by the cavity inner wall surface 1 a, stray light can be prevented from entering the cavity 1.

  FIG. 13 is a cross-sectional view schematically showing an example in which the electronic component 70 is mounted inside the cavity of the multilayer printed wiring board 200 of FIGS. 11 and 12.

  As shown in the drawing, after the multilayer printed wiring board 200 with a cavity is manufactured, an electronic component 70 can be mounted in the cavity 1. In this example, the electronic component 70 includes a plurality of electrode terminals 71 on the side surface. The plurality of electrode terminals 71 are connected to the mounting terminals 2 provided on the bottom surface of the cavity 1 through solder balls 72.

[Others]
The connection form of the electronic component embedded in the cavity is not limited to that shown in FIG. 13 and can take various forms. 14 to 17 are for explaining such an example. As in the first embodiment, a rigid wiring board 10 provided with a window serving as a cavity and a flexible wiring board 20 provided with no window are provided. It is sectional drawing which shows typically the state which mounted the electronic component 70 in the cavity 1 of the rigid-flexible 6 layer wiring board with a cavity laminated | stacked and integrated through the insulating layer 7. FIG.

  In FIG. 14, an electronic component 70 having a plurality of electrode terminals 71 on the side surface is placed inside the cavity 1, and each electrode terminal 71 of the electronic component 70 is attached to each mounting terminal 2 provided on the bottom surface of the cavity 1. In this example, the solder balls 72 are connected to each other. The multilayer printed wiring board of the present invention may be for mounting the electronic component 70 in the cavity 1 with such a configuration. Of course, not only the solder balls 72 but also solder bumps, conductive paste bumps, other bumps or the like may be used for connection.

  In FIG. 15, an electronic component 70 having a plurality of electrode terminals 71 on one main surface is placed inside the cavity 1 with the electrode terminal 71 surface facing the cavity opening, and each electrode terminal of the electronic component 70 is placed. Reference numeral 71 denotes an example in which bonding terminals 73 are connected to the respective mounting terminals 2 provided on the bottom surface of the cavity 1. The multilayer printed wiring board of the present invention may be for mounting the electronic component 70 in the cavity 1 with such a configuration.

  In FIG. 16, an electronic component 70 having a plurality of electrode terminals 71 on one main surface is placed inside the cavity 1 with the surface of the electrode terminal 71 facing the cavity opening, and each electrode terminal of the electronic component 70 is placed. 71 shows an example in which bonding wires 73 are connected to the respective mounting terminals 3 provided in the vicinity of the cavity side wall of the outermost layer of the rigid wiring board 10. The multilayer printed wiring board of the present invention may be for mounting the electronic component 70 in the cavity 1 with such a configuration. That is, the mounting terminals connected to the electrode terminals 71 of the electronic component 70 do not have to be provided on the bottom surface of the cavity 1.

  In FIG. 17, another electronic component 70 is mounted on the state shown in FIG. 14 so as to close the opening of the cavity 1, and each electrode terminal 71 is provided on the outermost layer of the rigid wiring board 10. An example in which each mounting terminal 3 is connected by a bonding wire 73 is shown. The multilayer printed wiring board of the present invention may connect electronic components with such a configuration.

  The connection method of the electronic component mounted in the cavity is not limited to these, and can take various forms.

  As described above, the configuration of the electronic component mounted in the cavity and the connection method thereof can take various forms. In any case, the inner wall surface of the cavity is coated with resin. Therefore, even if dust is generated near the side wall of the cavity due to the material of the multilayer printed wiring board, the dust does not enter the cavity. Therefore, dust generation in the cavity can be prevented.

The top view seen from the cavity opening part side of the multilayer rigid-flexible wiring board with a cavity which concerns on 1st Embodiment. Sectional drawing which showed typically the cross section along the AA of FIG. Typical sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board with a cavity. Typical sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board with a cavity. Typical sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board with a cavity. Typical sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board with a cavity. Typical sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board with a cavity. Typical sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board with a cavity. Sectional drawing which expands and shows an example of the cavity side wall vicinity typically. Sectional drawing which expands and shows typically another example of the cavity side wall vicinity. The top view seen from the cavity opening part side of the multilayer rigid wiring board with a cavity which concerns on 2nd Embodiment. Sectional drawing which showed typically the cross section along the BB line of FIG. The figure which shows the example which mounted the electronic component in the cavity of the multilayer rigid wiring board with a cavity of FIG. The figure which shows the example which mounted the electronic component in the cavity of the multilayer printed wiring board which concerns on this invention. The figure which shows the example which mounted the electronic component in the cavity of the multilayer printed wiring board which concerns on this invention. The figure which shows the example which mounted the electronic component in the cavity of the multilayer printed wiring board which concerns on this invention. The figure which shows the example which mounted the electronic component in the cavity of the multilayer printed wiring board which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cavity, 1a ... Cavity inner side wall, 2, 3 ... Mounting terminal, 4, 5 ... Connection land, 6 ... Conductor bump (interlayer connection conductor), 7 ... Hardened | cured material of prepreg containing resin which has fluidity | liquidity ( Insulating layer), 8 ... Solder resist, 10 ... Rigid wiring board (upper printed wiring board), 11 ... Hard insulating layer, 20 ... Flexible substrate (lower printed wiring board), 21 ... Flexible insulating layer, 12, 22 , 32 ... a wiring layer comprising a conductor pattern, 13, 23, 33 ... interlayer connection conductors, 14 ... windows (through holes), 26 ... conductor bumps, 27 ... an uncured prepreg containing a resin having fluidity, 51 ... Conformal material, 52 ... Release film, 61 ... Holding plate, 62 ... Holding plate with through holes, 63 ... Holding plate, 68 ... Support film (solder resist), 69 ... Dummy pattern, 70 ... Electronics Article, 71 ... electrode terminal, 72 ... solder balls, 73 ... bonding wire, 100 ... multilayer rigid with cavity - a flexible wiring board, 200 ... multilayer rigid wiring board having a cavity.

Claims (15)

A multilayer printed wiring board provided with a cavity for mounting electronic components,
An inner wall surface of the cavity is coated with a synthetic resin leached from an impregnating resin of a prepreg constituting the multilayer printed wiring board. 2. The multilayer printed wiring board according to claim 1 , wherein a black or dark dye or pigment is added to the resin coating the inner wall surface of the cavity. A multilayer printed wiring board in which an upper printed wiring board having a through hole serving as a cavity for mounting electronic components and a lower printed wiring board constituting a surface serving as the bottom of the cavity are laminated and integrated via a prepreg. ,
An inner wall surface of the cavity is coated with a synthetic resin leached from an impregnating resin of the prepreg. The lower printed wiring board and the upper printed wiring board are configured such that a substantially conical conductor bump formed in a connection land of the lower printed wiring board passes through the prepreg, and a tip thereof is the upper printed wiring board. The multilayer printed wiring board according to claim 3 , wherein the multilayer printed wiring board is electrically connected by an interlayer connection conductor that abuts on the connection land and is plastically deformed. The multilayer printed wiring board according to claim 3 or 4 , wherein the upper printed wiring board is a rigid wiring board, and the lower printed wiring board is a flexible wiring board. The multilayer printed wiring board according to any one of claims 3 to 5 , wherein a black or dark dye or pigment is added to the prepreg. The sidewall near the cavity bottom face of the lower printed wiring board, a part of is interposed below the upper printed wiring board, to claim 3, characterized in that disposed an insulating support film The multilayer printed wiring board as described. 8. The multilayer printed wiring board according to claim 7 , wherein the insulating support film is configured such that a portion inside the cavity is higher than a portion interposed below the upper printed wiring board. The insulative support film makes a portion inside the cavity higher than a portion interposed below the upper printed wiring board, and between the protective film provided on the bottom surface of the cavity of the lower printed wiring board. The multilayer printed wiring board according to claim 7 , wherein the multilayer printed wiring board is provided with a slight gap. The multilayer printed wiring board according to claim 1, wherein an electronic component is mounted in the cavity. A method for manufacturing a multilayer printed wiring board provided with a cavity for mounting electronic components,
A lower printed wiring board is prepared in which a conductor pattern is provided on at least one outer layer surface, and a conductor bump serving as an interlayer connection conductor is formed at a predetermined position of the conductor pattern, and the conductor bump formation of the lower printed wiring board is provided. While stacking uncured prepreg containing fluid resin on the surface and heating and pressurizing, creating the lower printed wiring board in which the tip of the conductor bump is exposed through the uncured prepreg,
An upper printed wiring board having a conductor pattern and a connection land corresponding to the conductor bump of the lower printed wiring board formed on at least one outer layer surface is prepared, and the upper printed wiring board is placed at a predetermined position on the upper printed wiring board. A step of making a through hole serving as the cavity;
The upper printed wiring board and the lower printed wiring board are laminated with the conductor bumps and the connection lands facing each other, heated and pressurized, and the leading end of the conductor bump exposed through the other printed wiring And a step of abutting the connection land of the plate, plastically deforming and electrically connecting and mechanically integrating, and coating the inner wall surface of the cavity with a synthetic resin leached from the impregnating resin of the prepreg. A method for producing a multilayer printed wiring board.   When the upper printed wiring board and the lower printed wiring board are stacked and heated and pressed, a first through hole corresponding to the through hole formed in the upper printed wiring board is formed on the upper printed wiring board. The pressing plate is aligned and laminated so that the through holes overlap each other, and further, the conformal material and the second pressing plate are laminated in order through the release film and heated and pressed. The method for producing a multilayer printed wiring board according to claim 11.   The through hole formed in the first pressing plate is formed smaller than the through hole formed in the upper printed wiring board, and when the through holes are overlapped, the through hole of the first pressing plate and the 13. The method for producing a multilayer printed wiring board according to claim 11 or 12, wherein a difference between each edge portion of the through hole of the upper printed wiring board is slightly larger than a coating thickness of the inner wall surface of the cavity. .   The method for manufacturing a multilayer printed wiring board according to any one of claims 11 to 13, wherein the upper printed wiring board is a rigid wiring board, and the lower printed wiring board is a flexible wiring board. The method for manufacturing a multilayer printed wiring board according to claim 11, further comprising a step of mounting an electronic component in the cavity.

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