JP2005332848A - Multilayered wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered wiring board wherein conductivity paths are established between the front and rear surfaces of a core substrate to make a high density wiring possible and a semiconductor chip can be stably and surely mounted, and also to provide its manufacturing method. <P>SOLUTION: In the multilayered wiring board having interconnections formed on top of the core substrate via an electric insulation layer, the core substrate is formed with a plurality of through holes and has a conductive material located inside the through holes to establish the conductivity paths between the front and rear surfaces. On one surface of the core substrate, the conductive material projects from the surface of the core substrate to form bumps having such a shape as to rise nearly at the center. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multilayer wiring board and a manufacturing method thereof, and more particularly to a multilayer wiring board on which high-density wiring for mounting a semiconductor chip is made and a manufacturing method for manufacturing such a multilayer wiring board.

  In recent years, as electronic devices become more sophisticated, smaller, and lighter, semiconductor packages are required to be smaller, have more pins, and have finer pitches for external terminals, and there is an increasing demand for high-density wiring boards. It is getting stronger. For this reason, an LSI is directly mounted on a printed wiring board, or a CSP (Chip Size Package) or BGA (Ball Grid Array) is mounted on a printed wiring board. And in order to cope with the higher density of printed wiring boards, the printed wiring board was produced by a build-up wiring technique in which wiring and vias (Via) are stacked in layers via an electrical insulating layer on a core substrate. Multilayer wiring boards have come to be used.

The core substrate is generally provided with through-holes for electrically connecting the upper and lower conductors of the substrate, and the core substrate is provided with low-density wiring produced by a subtractive method or additive method on one or both sides. Used as a multilayer wiring board as a substrate. However, the conventional through hole has a hole formed by drilling, and there is a problem that the hole diameter is limited in terms of miniaturization, and the degree of freedom in wiring design is limited.
For this reason, various wiring methods have been proposed and implemented as a core substrate manufacturing method (Patent Document 1, Patent Document 2), and multilayer wiring boards in which a wiring layer is formed on these core substrates are used. Yes.
JP-A-5-144978 JP-A-11-345933

  However, along with miniaturization and narrowing of the wiring of the core substrate, miniaturization is required for the multilayer wiring layer provided on the core substrate by the build-up method, and there is an increasing demand for narrow pitch and high density wiring. The multilayer wiring board in which wiring is formed on a conventional core substrate by a conventional process has a problem that it cannot meet the required electrical characteristics and the demand for miniaturization for high-density wiring.

In addition, with high-density mounting due to narrow pitch and multiple pins, the electrical connection between the wiring board and the semiconductor chip, etc. is done using flip chip technology, etc., for mounting the semiconductor chip face down instead of the conventional wire bonding technology. It is supposed to be. However, as the hole diameter of the through hole for high-density mounting is reduced, the diameter of the bump located at the opening of the through hole is also reduced. For this reason, when mounting the semiconductor chip, there is a problem that the mounting pad becomes small and it becomes difficult to supply the solder to the small-diameter pad. There is also a demand for easy and reliable connection when mounting a semiconductor chip using heating or ultrasonic waves.
The present invention has been made in view of the above circumstances, and a multi-layer wiring board capable of stably and surely mounting a semiconductor chip, in which the core board is electrically connected to each other so that high-density wiring is possible. And it aims at providing the manufacturing method.

In order to achieve such an object, the present invention provides a multilayer wiring board comprising a core substrate and a wiring formed on the core substrate via an electrical insulating layer, wherein the core substrate includes a plurality of through-holes. And a conductive material that is located in the through hole and that conducts both front and back, and the conductive material protrudes from the surface of the core substrate on one surface of the core substrate to form a bump having a raised shape at a substantially central portion. The configuration is as follows.
As another aspect of the present invention, the core substrate is configured such that the thermal expansion coefficient in the XY direction is in the range of 2 to 20 ppm.
As another aspect of the present invention, the through hole has an inner diameter in the range of 5 to 100 μm.

As another aspect of the present invention, the conductive material protrudes from the surface of the core substrate to form a land on the other surface of the core substrate.
As another aspect of the present invention, the through hole has a tapered shape in which the inner diameter on the bump forming side is larger than the inner diameter of the other end.
As another aspect of the present invention, the conductive material is made of an electrolytic plating metal.
As another aspect of the present invention, the core substrate is configured to include an insulating layer on both surfaces and the inner wall surface of the through hole, and the thickness of the insulating layer is in the range of 1 to 4.5 μm on the core substrate surface. The inner wall surface of the through hole is configured to have a range of 0.3 to 1 μm.
As another aspect of the present invention, an insulating resin layer is provided so as to expose the bump on the bump forming surface side of the core substrate, and the elastic modulus of the insulating resin layer is 2.9 MPa or less. .
As another aspect of the present invention, the height of the bump protruding from the core substrate surface is in the range of 1 to 50 μm.

  The present invention also provides a method for manufacturing a multilayer wiring board comprising a core substrate and wiring formed on the core substrate via an electrical insulating layer, wherein the core material is perforated with fine holes of a predetermined size. Forming a through hole, forming a base conductive thin film on one surface of the core material, forming a desired resist pattern on the base conductive thin film on the core material, and electroplating from the surface side A step of forming an electroplating site reaching a predetermined depth in the through hole, a step of covering the electroplating site exposed on the core material surface with an insulating material, and the other of the core material The electrolytic plating is performed on the electrolytic plating site in the through hole from the surface of the through hole so that the inside of the through hole is filled with a conductive material made of electrolytic plating metal, and the conductive material protrudes from the core material surface. A step of forming a bump having a substantially central shape, a step of removing the resist pattern, removing the exposed underlying conductive thin film, and forming a core substrate; And a step of forming a wiring through an insulating layer.

As another aspect of the present invention, the through hole is formed by an ICP-RIE method or a sand blast method.
As another aspect of the present invention, after the through hole is formed, an insulating layer is formed on the surface of the core material including the inside of the through hole.
As another aspect of the present invention, the base conductive thin film is formed by vacuum deposition, and the base conductive thin film is not formed on the inner wall surface of the through hole.
As another aspect of the present invention, the electrolytic plating is configured to be any one of an electrolytic copper plating method, an electrolytic silver plating method, and an electrolytic gold plating method.
As another aspect of the present invention, the core material is configured to be one of silicon, ceramic, glass, and glass-epoxy composite material having a thermal expansion coefficient in the XY direction of 2 to 20 ppm.

According to the present invention, the conductive material located in the through hole provides conduction between the front and back of the core substrate, and the conductive material protrudes from the surface of the core substrate to form bumps, thereby facilitating the mounting of the semiconductor chip. In addition, since the bump has a raised shape at the center, the connection between the pad and the bump of the semiconductor chip and the connection using ultrasonic waves can be stably and reliably performed.
Further, in the present invention, a conductive material is filled into the through hole formed in the core material by electrolytic plating, thereby forming a bump having a shape in which the central portion is raised while providing conduction between the front and back surfaces of the conductive material, and a polishing step Therefore, contamination due to polishing can be prevented, and the process becomes simple. In addition, when the insulating layer is formed on the surface of the core material, there is no polishing step after filling with the conductive material as described above, so that damage to the insulating layer can be prevented. In addition, when the through hole is formed in a tapered shape, it is possible to speed up the formation of the through hole in the core material and the filling of the conductive material by electrolytic plating. In this case, when an insulating layer is further formed on the surface of the core material In addition, the insulating layer can be formed on the inner wall surface of the through hole with a uniform thickness.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Multilayer Wiring Board FIG. 1 is a partial longitudinal sectional view showing an embodiment of a multilayer wiring board according to the present invention. In FIG. 1, a multilayer wiring board 1 of the present invention includes a core substrate 2 and wiring formed on one surface 2 b of the core substrate 2.
The core substrate 2 constituting the multilayer wiring board 1 includes a core material 2 ′ in which a plurality of through holes 4 are formed, an insulating layer 3 that is formed on the entire surface of the core material 2 ′ including each through hole 4, and each through-hole. A conductive material 5 is provided in the hole 4, and the conductive material 5 provides conduction between the surface 2 a and the surface 2 b through the through hole 4.

The through hole 4 formed in the core substrate 2 may have an inner diameter in the range of 5 to 100 μm, preferably in the range of 5 to 50 μm, and has a tapered shape with one wide opening diameter as illustrated. The through-hole 4 may have a straight shape with a substantially constant inner diameter in the thickness direction of the core material 2 ', or a shape in which the inner diameter is narrow at the approximate center in the thickness direction of the core material 2'. Etc. The core substrate 2 can have a thickness in the range of 20 to 600 μm, preferably 50 to 250 μm. If the thickness of the core substrate 2 is less than 20 μm, sufficient strength as a support cannot be maintained, and if it exceeds 600 μm, the semiconductor device is undesirably thinned.
The conductive material 5 located in the through hole 4 of the core substrate 2 protrudes so as to form bumps 5a on one surface of the core substrate 2, and protrudes so as to form lands 5b on the other surface.

The bump 5a has a shape with a raised central portion, and an insulating resin layer 6 is formed on the core substrate so as to cover the peripheral portion of the bump 5a. The diameter D1 of the bump 5a may be equal to or larger than the opening diameter of the through hole 4 on the surface 2a of the core substrate 2, and in the case of being larger, it is 5 than the inner diameter of the opening of the through hole 4. About 50 μm larger. The protrusion height H1 of the bump 5a can be about 1 to 200 μm. The bump 5a in the illustrated example has a shape obtained by cutting off a part of a sphere. However, in the present invention, the shape of the bump 5a is not limited to that in the illustrated example, and a shape in which a substantially central portion is raised. I just need it. For example, the swell may be steep or gentle, and an inflection point may exist on the ridge line of the swell.
Further, the thickness of the insulating resin layer 6 is preferably set so that the bumps 5 a protrude 1 μm or more from the surface of the insulating resin layer 6.

The land 5b may have a diameter D2 that is equal to or larger than the opening diameter of the through hole 4 on the surface 2b of the core substrate 2, and in the case of being larger than the inner diameter of the opening of the through hole 4. Is about 5 to 100 μm. The protruding height H2 of the land 5b can be about 1 to 50 μm.
The wiring that constitutes the multilayer wiring board 1 is a multilayer wiring in the illustrated example, and a conductive material of a predetermined through hole 4 is formed on the surface 2b of the core substrate 2 via the first electrical insulating layer 9a at the via portion 7a. A first layer wiring 8a formed so as to be connected to 5 (land 5b), and a predetermined one layer on the first layer wiring 8a via a second electrical insulating layer 9b at a via portion 7b. A second-layer wiring 8b formed so as to be connected to the second-layer wiring 8a, and a predetermined second-layer wiring on the second-layer wiring 8b via a third-layer electric insulating layer 9c in the via portion 7c. And a third-layer wiring 8c formed so as to be connected to 8b. An insulating layer is provided on the surface 2b of the core substrate 2 so as to be flush with the upper surface of the land 5b to form a flat surface, and the first electric insulating layer 9a is disposed on the flat surface. There may be.

  In the multilayer wiring board 1 of the present invention as described above, conduction between the front and back of the core substrate 2 is taken by the conductive material 5 located in the through hole 4, and the conductive material 5 protrudes from the surface of the core substrate 2 to form the bumps 5 a. None, since the bump 5a has a raised shape at the center, it can be stably and reliably connected to the pad in the semiconductor chip mounting or using ultrasonic waves. Further, even when the inner diameter of the through hole 4 is small, since the conduction between the front and back sides is ensured by the conductive material 5, a sufficient space for the wiring disposed on the core substrate 2 can be secured, In addition to a high degree of freedom in wiring design, a desired high-density wiring can be formed with a smaller number of layers, thereby enabling a reduction in thickness.

In the multilayer wiring substrate 1 of the present invention described above, the core substrate 2 has a thermal expansion coefficient in the XY direction (a plane parallel to the surface of the core substrate) of 2 to 20 ppm, preferably 3 to 17 ppm. . Such a core substrate can be manufactured using, for example, a core material 2 'such as silicon, ceramic, glass, glass-epoxy composite material or the like. In the present invention, the thermal expansion coefficient is measured by TMA (thermal mechanical analysis).
The insulating layer 3 described above may be a thin film made of silicon dioxide, silicon nitride, titanium nitride or the like alone or laminated, and has a thickness of 1 to 4.5 μm on the surface of the core substrate 2, preferably 2 to 4. 5 μm and 0.3 to 1 μm, preferably about 0.4 to 0.8 μm, on the inner wall surface of the through hole 4. In addition, when the material of the core material 2 ′ has electrical insulation and the conductive material 5 does not permeate, the insulating layer 3 may be omitted.

Further, the conductive material 5 filled in the through hole 4 of the core substrate is an electrolytic plating metal, and can be, for example, copper, silver, gold, or the like.
The material of the multilayer wirings 8a, 8b and 8c formed on the core substrate and the material of the via portions 7a, 7b and 7c can be conductive materials such as copper, silver, gold and chromium. . The material of the insulating resin layer 6 formed on the core substrate and the materials of the insulating layers 9a, 9b, 9c are organic insulating materials such as epoxy resin, benzocyclobutene resin, cardo resin, polyimide resin, and the like. An insulating material such as a combination of a material and glass fiber can be used. In particular, the insulating resin layer 6 formed so as to expose the bumps 5a on the surface 2a side of the core substrate 2 has an elastic modulus of 2.9 MPa or less, preferably 1.0 to 2.8 MPa. . By setting the elastic modulus of the insulating resin layer 6 within the above range, the thermal stress strain generated between the core substrate 2 and the semiconductor chip mounted on the multilayer wiring substrate 1 can be reduced.
The embodiment of the multilayer wiring board described above is an example, and the multilayer wiring board of the present invention is not limited to this. For example, the number of wiring layers formed on the core board is not limited.

Next, a method for manufacturing a multilayer wiring board according to the present invention will be described with reference to the drawings.
2 to 4 are process diagrams for explaining an embodiment of a method for producing a multilayer wiring board according to the present invention, using the multilayer wiring board 1 as an example.
In the method for manufacturing a multilayer wiring board of the present invention, the core material 2 'for the core substrate is polished to a predetermined thickness, and a predetermined mask pattern 11 is formed on one surface 2'a of the core material 2' ( 2 (A)), through-holes 4 having a predetermined size are formed in the core material 2 'by etching using the mask pattern 11 as a mask (FIG. 5 (B)). The core material 2 'is made of a material having a thermal expansion coefficient in the XY direction (a plane parallel to the surface 2'a of the core material 2') of 2 to 20 ppm, preferably 3 to 17 ppm, such as silicon, ceramic, Glass, glass-epoxy composite material, and the like can be used. Etching can be performed, for example, by dry etching by ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching) method or wet etching.

The opening diameter of the through hole 4 to be formed can be appropriately set within the range of 5 to 100 μm, preferably 5 to 50 μm, and can be adjusted by the opening diameter of the mask pattern 11.
In addition, a mask pattern may be formed on both surfaces of the core material 2 ', and the through hole 4 may be formed from both surfaces by sandblasting. Alternatively, a mask pattern may be formed on one surface of the core material 2', and sandblasting from this surface. Through hole 4 may be formed by the following. Further, a fine hole is formed in the core material 2 'at a predetermined depth by any of the methods described above, and then the through hole 4 is formed by polishing the opposite surface of the core material 2' to expose the fine hole. May be.

Next, the mask pattern 11 is removed, and the insulating layer 3 is formed on the surface of the core material 2 ′ and the inner wall surface of the through hole 4 (FIG. 5C). The insulating layer 3 can be formed as a single layer film such as a silicon dioxide film, a silicon nitride film, a titanium nitride film, or a desired two or more kinds of laminated films using a vacuum film forming method such as a plasma CVD method. . Alternatively, a silicon oxide precursor solution or an insulating resin such as a benzocyclobutene resin, a cardo resin, or a polyimide resin may be applied to the core material surface and thermally cured by a coating method. Further, when the material of the core material 2 'is silicon, a silicon dioxide film can be formed on the surface of the core material 2' by thermal oxidation to form the insulating layer 3. Further, a silicon nitride film, a titanium nitride film or the like can be further laminated on the silicon dioxide film by a vacuum film forming method to form the insulating layer 3. In this embodiment, since the shape of the through hole 4 is a tapered shape, the thickness of the insulating layer 3 formed on the wall surface in the through hole 4 can be made more uniform.
In addition, when the material of core material 2 'has an electrical insulation and permeation of the conductive material 5 does not occur, the insulating layer 3 may not be formed.

  Next, a base conductive thin film 12 is formed on the insulating layer 3 from the one surface 2'b side of the core material 2 '(FIG. 2D), and then a desired resist pattern 13 is formed on the base conductive thin film 12. (FIG. 3A). The base conductive thin film 12 can be formed by electroless plating as a thin film of chromium, titanium, titanium nitride, or the like, or a thin film containing these (for example, a thin film made of copper and chromium). Further, titanium nitride is provided on the insulating layer 3 (the surface of the core material 2 ′ and the inner wall surface of the through hole 4) using MOCVD (Metal Organic-Chemical Vapor Deposition) using plasma to form a barrier metal layer. Then, the underlying conductive thin film 12 may be used. Further, the underlying conductive thin film 12 may be formed by a vacuum film forming method such as a sputtering method or a vapor deposition method. The underlying conductive thin film 12 is not formed on the inner wall surface of the through hole 4 (on the insulating layer 3 formed on the inner wall surface) from the viewpoint of forming an electroplating site in the next step, but the surface of the core material 2 '. It is preferable to form only on the insulating layer 3 on 2′b. The resist pattern 13 can be formed, for example, by laminating a dry film as a photosensitive resist on the underlying conductive thin film 12, and exposing and developing through a desired photomask.

  Next, the conductive material is closed by electrolytic plating using the base conductive thin film 12 as a power feeding layer, and is deposited to a predetermined depth to form the electrolytic plating site 15 (FIG. 3B). )). The electrolytic plating site 15 fills the inside of the through hole 4 to a predetermined depth and projects outward from the surface 2'b of the core material 2 '. The formation of the electrolytic plating site 15 can be performed by electrolytic copper plating, electrolytic silver plating, electrolytic gold plating, or the like.

Next, an insulating layer 14 is formed so as to cover the electrolytic plating site 15 exposed on the surface 2'b of the core material 2 '(FIG. 3C). Next, a conductive material is deposited on the electrolytic plating site 15 in the through hole 4 by performing electrolytic plating using the base conductive thin film 12 as a power feeding layer (FIG. 3D). As a result, the conductive material 5 is filled without generating a gap in the through hole 4, and the conductive material 5 is projected from the surface 2'a of the core material 2 'to form a bump 5a having a raised shape at the center. To do. Electrolytic plating for forming the bumps 5a can be performed by controlling the plating time and current value (current density) during electrolytic plating.
In this embodiment, since the shape of the through hole 4 is a taper shape, it is possible to increase the filling speed of the conductive material 5 by electrolytic plating from the surface 2'a side of the core material 2 '.

Next, by removing the resist pattern 13 on the surface 2'b side of the core material 2 'and the exposed underlying conductive thin film 12, the through hole 4 is filled with the conductive material 5 and the front and back are made conductive. At the same time, the core substrate 2 is obtained in which one end portion of the conductive material 5 protrudes in a raised shape at the center portion to form a bump 5a, and the other end portion protrudes to become a land 5b (FIG. 4A). ). In addition, the core board | substrate 2 in FIG. 4 (A) has the core material 2 'shown in FIG. 2 (A)-FIG.
In the present invention, since a polishing step is unnecessary, contamination due to polishing can be prevented, and the process becomes simple. Furthermore, the insulating layer 3 provided on the surface of the core material 2 'can be prevented from being damaged in the polishing process.

Next, the insulating resin layer 6 is formed on one surface 2a of the core substrate 2, and the wiring is formed on the other surface 2b of the core substrate 2 via the electric insulating layer, whereby the multilayer wiring substrate 1 is obtained. (FIG. 4B).
The insulating resin layer 6 can be formed by applying a photosensitive resin coating solution to the surface 2a of the core substrate 2, and exposing and developing through a mask pattern for exposing the bumps 5a. The thickness of the insulating resin layer 6 is preferably set so that the bumps 5 a protrude from the surface of the insulating resin layer 6 by 1 μm or more.

  Further, in the wiring formation, for example, an electrical insulating layer 9a is formed so as to cover the land 5b on the surface 2b side of the core substrate 2, and a desired portion of the land 5b is exposed using a carbon dioxide gas laser, a UV-YAG laser, or the like. In this way, a small-diameter hole is formed at a predetermined position of the electrical insulating layer 9a. After cleaning, a conductive layer is formed by electroless plating in the hole and on the electrical insulating layer 9a. A dry film resist is laminated on the conductive layer, and a resist pattern is formed by performing desired pattern exposure and development. To do. Thereafter, using this resist pattern as a mask, a conductive material is deposited by electroplating on the exposed part including the hole part to form the via part 7a and the first wiring 8a, and the resist pattern and the conductive layer are removed. Further, a conductive layer is formed in the hole and on the electrical insulating layer 9a by a vacuum film-forming method such as sputtering, a mask pattern is formed on the conductive layer, and the conductive layer is etched to form via portions 7a and The first layer wiring 8a may be formed, and then the mask pattern may be removed. Such operations are repeated to form a plurality of buildup layers.

In the illustrated example, the second-layer wiring 8b is formed on the first-layer wiring 8a so as to be connected to the predetermined first-layer wiring 8a through the second-layer electrical insulating layer 9b at the via portion 7b. Further, a third-layer wiring 8c is formed on the second-layer wiring 8b so as to be connected to the predetermined second-layer wiring 8b through the third-layer electric insulating layer 9c at the via portion 7c. The wiring has a three-layer structure.
The method for manufacturing a multilayer wiring board according to the present invention is not limited to the one shown in the above-described embodiment, and may be applied to, for example, manufacturing a multilayer wiring board having four or more wiring layers. Can do.

Next, the present invention will be described in more detail with specific examples.
[Example]
A silicon wafer having a thickness of 625 μm was prepared as a core material, and a silicon nitride film (thickness of 5 μm) was formed on one surface of the core material by a plasma CVD method. Next, a positive photoresist (OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied onto the silicon nitride film, and a resist pattern was formed by exposure and development through a photomask for forming a through hole. . Next, the silicon nitride film exposed from the resist pattern was dry-etched using CF ₄ as an etching gas, and then the resist pattern was stripped with a dedicated stripping solution to form a mask pattern made of silicon nitride. The thermal expansion coefficient of the above silicon wafer in the XY direction (a plane parallel to the surface of the silicon wafer) was 3 ppm. In addition, the mask pattern had circular openings with a diameter of 30 μm formed at a pitch of 100 μm.

Next, silicon exposed from the mask pattern was dry-etched using SF ₆ as an etching gas by an ICP-RIE apparatus to form a through hole. This through hole had a tapered shape with one opening diameter of 35 μm and the other opening diameter of 20 μm.
Next, the mask pattern was removed from the core material using acetone. Thereafter, a thermal oxidation treatment (1050 ° C., 20 minutes) was applied to the core material in which the through hole was formed, and a silicon dioxide film was formed on the surface of the core material (including the inner wall surface of the through hole). A silicon nitride film was formed on the silicon dioxide film by a plasma CVD method, and a titanium nitride film was further formed by an MOCVD method to form an insulating film having a three-layer structure. This insulating film was 4 μm on the surface of the core material and 1 μm on the inner wall surface of the through hole.

  Thereafter, a base conductive thin film having a thickness of 0.2 μm was formed on one surface of the core material (surface on which the end portion of the through hole having the smaller opening diameter was exposed) by sputtering in the order of titanium-copper. Next, a dry film resist (APR manufactured by Asahi Kasei Co., Ltd.) was laminated on the underlying conductive thin film. Subsequently, the resist pattern (thickness 15 micrometers) was formed by exposing and developing through the photomask for land formation. Electrolytic copper plating was performed using this resist pattern as a mask and the above-mentioned underlying conductive thin film as a power feeding layer. As a result, it was possible to form an electroplating site that blocked the opening of the through hole while protruding about 30 μm into the through hole and protruded from the core material surface.

Next, an insulating resin tape was applied so as to cover the electrolytic plating portion, and the electrode was covered.
Next, electrolytic copper plating was performed using the base conductive thin film as a power feeding layer. As a result, the plated copper, which is a conductive material, is deposited on the electrolytic plating site in the through hole to fill the through hole, and the conductive material protrudes from the surface of the core material, so that the center portion has a raised shape. Bumps were formed. The bump formation in the electrolytic copper plating at this time was controlled by adjusting the plating time and the current density.

Next, the core substrate was obtained by removing the resist pattern and the underlying conductive thin film. The core substrate is electrically connected to the front and back sides by a conductive material filled in the through hole. The conductive material has a land with a diameter of 50 μm and a height of 5 μm on the end side of the through hole having an opening diameter of 20 μm. On the end of the through hole having a diameter of 35 μm, a bump having a diameter of 50 μm, a height of 50 μm and a raised central portion was provided.
Next, a photosensitive polyimide (D7320 manufactured by Fuji Film Arch Co., Ltd.) is applied to the surface of the core substrate on which the bumps are formed, spinner applied, exposed through a photomask for exposing the bumps, developed, and then heated. A curing treatment was performed. Thus, an insulating resin layer (thickness 40 μm) was formed so as to expose the bumps with a diameter of 45 μm.

In addition, a photosensitive benzocyclobutene resin composition (Cycloten 4024 manufactured by Dow Chemical Co., Ltd.) is spinner-coated on the surface of the core substrate on which lands are formed, and exposed through a photomask for land formation. After development, a thermosetting treatment was performed to form an electrically insulating layer (thickness 7 μm) with exposed lands. A photosensitive benzocyclobutene resin composition (Cycloten 4024 manufactured by Dow Chemical Co., Ltd.) is spinner applied on the electrical insulating layer formed for planarization in this way, and dried to form an electrical insulating layer having a thickness of 8 μm. did. Next, exposure and development were performed to form a small-diameter hole (inner diameter 25 μm) at a predetermined position of the electrical insulating layer so that a predetermined portion of the land was exposed. After cleaning, a conductive layer made of titanium and copper was formed by sputtering in the hole and on the electrical insulating layer, and a liquid resist (LA900 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied on the conductive layer. Next, an insulating pattern for wiring formation was formed by exposure and development through a photomask for wiring formation. Electrolytic copper plating (thickness: 4 μm) was performed using this insulating pattern as a mask, and then the insulating pattern and the conductive layer were removed. As a result, a first layer wiring was formed via the electrical insulating layer. The above wiring was connected to the land through a via portion (diameter 25 μm).
Further, the same operation was performed to form a wiring through the electrical insulating layer. As a result, a multilayer wiring board as shown in FIG. 1 was obtained.

[Comparative example]
First, in the same manner as in Example 1, a through hole was formed in a core material made of a silicon wafer, and an insulating film having a three-layer structure made of a silicon dioxide film, a silicon nitride film, and a titanium nitride film was formed in the core material.
Next, a dry film resist (APR manufactured by Asahi Kasei Co., Ltd.) was laminated on one surface of the core material (the surface where the end portion of the through hole having the smaller opening diameter was exposed). Subsequently, the resist pattern (thickness 15 micrometers) was formed by exposing and developing through the photomask for land formation. This resist pattern was provided with a circular opening having a diameter of 35 μm around the opening portion of the through hole. Further, a dry film resist (APR manufactured by Asahi Kasei Co., Ltd.) was laminated on the other surface of the core material (the surface where the end portion of the through hole having the larger opening diameter was exposed). Subsequently, the resist pattern (thickness 15 micrometers) was formed by exposing and developing through the photomask for bump formation. This resist pattern was provided with a circular opening having a diameter of 40 μm around the opening portion of the through hole.

  Next, a conductive paste containing copper particles was filled into the through-holes by screen printing and subjected to a curing process (170 ° C., 20 minutes). Thereafter, the conductive material protruding on both surfaces of the core material is polished using MCP150X manufactured by Fujikoshi Machine Industry Co., Ltd., so that the surface of the conductive material filled in the through hole and the surface of the resist pattern are flush with each other. . Next, the resist pattern was removed to obtain a core substrate. The core substrate is electrically connected to the front and back surfaces by a conductive material filled in the through hole. The conductive material has a land having a diameter of 50 μm and a height of 5 μm on the end side of the through hole having an opening diameter of 35 μm. A bump having a diameter of 50 μm, a height of 15 μm, and a flat top surface was provided on the end of the through hole having a diameter of 20 μm.

Photosensitive benzocyclobutene (BCB manufactured by Dow Chemical Co., Ltd.) is spinner-coated on the surface of the core substrate on which the bumps are formed, exposed through a photomask for exposing the bumps, developed, and then heated. A curing treatment was performed. Thus, an insulating resin layer (thickness: 15 μm) was formed so as to be flush with the upper surface of the bump.
Next, as in the example, an electrical insulating layer (thickness: 7 μm) was formed on the land forming surface of the core substrate, and a wiring was formed on the electrical insulating layer to obtain a comparative multilayer wiring substrate.

[Evaluation of multilayer wiring board]
A semiconductor chip was mounted on the multilayer wiring board (Example, Comparative Example) described above, and the following temperature cycle test was performed. As a result, the multilayer wiring board of the present invention had good connection with all the pads of the semiconductor chip, and the variation in resistance value was within 10%. However, in the multilayer wiring board of the comparative example, the variation of the resistance value exceeded 30%.
(Temperature cycle test)
Hold at -55 ° C for 15 minutes, then heat to 125 ° C in 30 minutes,
The process of holding for 1 minute and then cooling to −55 ° C. in 30 minutes is repeated 1000 times.

  The present invention is useful for various applications including a multilayer wiring board provided with high-density wiring.

It is a partial longitudinal cross-sectional view which shows one Embodiment of the multilayer wiring board of this invention. It is process drawing which shows one Embodiment of the manufacturing method of the multilayer wiring board of this invention. It is process drawing which shows one Embodiment of the manufacturing method of the multilayer wiring board of this invention. It is process drawing which shows one Embodiment of the manufacturing method of the multilayer wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer wiring board 2 ... Core board | substrate 2 '... Core material 3 ... Insulating layer 4 ... Through-hole 5 ... Conductive material 5a ... Bump 5b ... Land 6 ... Insulating resin layer 7a, 7b, 7c ... Via part 8a, 8b, 8c ... Wiring 9a, 9b, 9c ... Electrical insulating layer 14 ... Insulating layer (insulating material)
15 ... Electrolytic plating site

Claims (17)

In a multilayer wiring board comprising a core substrate and wiring formed on the core substrate via an electrical insulating layer,
The core substrate includes a plurality of through-holes and a conductive material that is located in the through-hole and has electrical conductivity on the front and back sides, and the conductive material protrudes from the core substrate surface on one surface of the core substrate and is substantially in the center. A multilayer wiring board characterized by forming bumps having a raised shape.   2. The multilayer wiring board according to claim 1, wherein the core substrate has a thermal expansion coefficient in an XY direction of 2 to 20 ppm.   3. The multilayer wiring board according to claim 1, wherein an inner diameter of the through hole is in a range of 5 to 100 μm.   4. The multilayer wiring board according to claim 1, wherein the conductive material protrudes from the surface of the core substrate to form a land on the other surface of the core substrate.   5. The multilayer wiring board according to claim 1, wherein the through hole has a tapered shape in which an inner diameter on the bump forming side is larger than an inner diameter of the other end portion.   6. The multilayer wiring board according to claim 1, wherein the conductive material is made of electrolytic plating metal.   The multilayer wiring board according to claim 1, wherein the core substrate includes an insulating layer on both sides and an inner wall surface of the through hole.   8. The multilayer wiring board according to claim 7, wherein the thickness of the insulating layer is in the range of 1 to 4.5 [mu] m on the surface of the core substrate and in the range of 0.3 to 1 [mu] m on the inner wall surface of the through hole.   The insulating resin layer is provided so that the said bump may be exposed to the said bump formation surface side of the said core substrate, The elasticity modulus of this insulating resin layer is 2.9 Mpa or less, The Claim 1 thru | or 8 characterized by the above-mentioned. A multilayer wiring board according to any one of the above.   The multilayer wiring board according to claim 1, wherein a protruding height of the bump from the core substrate surface is in a range of 1 to 50 μm. In a method for manufacturing a multilayer wiring board comprising a core substrate and wiring formed on the core substrate via an electrical insulating layer,
Forming a through hole by drilling a micro hole with a predetermined size in the core material;
A base conductive thin film is formed on one surface of the core material, a desired resist pattern is formed on the base conductive thin film on the core material, and electrolytic plating is performed from the surface side, whereby predetermined holes in the through hole are formed. Forming an electroplating site that reaches a depth of
Coating the electroplating site exposed on the core material surface with an insulating material;
By performing electroplating on the electroplating site in the through hole from the other surface of the core material, the inside of the through hole is filled with a conductive material made of an electroplated metal, and from the core material surface to the conductive material Projecting a bump to form a bump having a raised shape at a substantially central portion;
Removing the resist pattern and removing the exposed underlying conductive thin film to form a core substrate;
Forming a wiring on the core substrate through an electrical insulating layer. A method for manufacturing a multilayer wiring board, comprising:   12. The method of manufacturing a multilayer wiring board according to claim 11, wherein the through hole is formed by an ICP-RIE method or a sand blast method.   The multilayer wiring board according to claim 11 or 12, wherein the through hole has a tapered shape in which one inner diameter of the opening is larger than an inner diameter of the other end.   14. The method for manufacturing a multilayer wiring board according to claim 11, wherein after forming the through hole, an insulating layer is formed on the surface of the core material including the inside of the through hole.   15. The multilayer wiring board according to claim 11, wherein the underlying conductive thin film is formed by a vacuum deposition method, and the underlying conductive thin film is not formed on the inner wall surface of the through hole. Method.   16. The method of manufacturing a multilayer wiring board according to claim 11, wherein the electrolytic plating is any one of an electrolytic copper plating method, an electrolytic silver plating method, and an electrolytic gold plating method.   The core material is any one of silicon, ceramic, glass, and glass-epoxy composite material having a thermal expansion coefficient in the XY direction of 2 to 20 ppm. A method for producing a multilayer wiring board according to claim 1.

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