JP2002151853A - Multilayer printed wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of decreasing the size of through-holes for increasing the density of a multilayer printed wiring board reduces the thickness of an electrical insulative base, resulting in that the entire multilayer printed wiring board has a flexibility of losing the rigidity of the board and such the multilayer printed wiring board has poor mountability of electronic components, and if a force is exerted on the board after mounting electronic components, stresses are concentrated on connections of the electronic components to the multilayer printed wiring board to lower the reliability at the connections. SOLUTION: A reinforcing layer provided on the surface of a multilayer printed wiring board having a thin electric insulation layer and a flexibility on the whole of the board raises the rigidity of the board. Forming the reinforcing layer prevents stresses from concentration on electronic component mounting parts, when a force is exerted on the board after mounting the electronic components. This improves the connection reliability of the electronic components to the multilayer printed wiring board, thereby obtaining a very high connection reliability with the electronic components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board for making electrical connection between layers by a conductor such as a conductive paste and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and high performance of electronic equipment, multilayer wiring boards on which semiconductor chips such as LSIs can be mounted at a high density have been supplied at a low cost not only for industrial use but also in the field of consumer equipment. There is a strong demand for it. In such a multilayer wiring board, it is important that a plurality of wiring patterns formed at a fine wiring pitch can be electrically connected with high connection reliability.

[0003] In response to such market demand, instead of the metal plating conductor on the inner wall of the through hole, which has been the mainstream of the conventional interlayer connection of the multilayer wiring board, an arbitrary electrode of the multilayer printed wiring board is replaced with an arbitrary wiring pattern. Inner via hole connection method that allows interlayer connection at positions, ie, all layers IVH
There is a so-called structural resin multilayer substrate (Japanese Unexamined Patent Publication No.
268345). This is because it is possible to fill the via holes of the multilayer printed wiring board with a conductor and connect only the necessary layers, and to provide the inner via holes directly under the component lands. And high-density mounting.

Further, a structure has been proposed for reducing the size of an inner via hole in order to realize a high-density interlayer connection and for realizing high reliability (Japanese Patent Laid-Open No. 20-204).
00-77800). An example of the structure and manufacturing method of this conventional multilayer wiring board will be described with reference to FIG.

[0005] First, as shown in FIG. 8 (a), an adhesive layer 804 is formed on both sides of an electrically insulating substrate 802, and a cover film 803 is formed on one adhesive layer surface. A desired wiring layer 805 is formed on the support base 801 on the side of the electrically insulating base on which the cover film is not formed.
The transfer substrate on which is formed is disposed. In this state, when bonding is performed by applying temperature and pressure by lamination, FIG.
The state shown in (b) is obtained. In this bonding step, it is preferable that the temperature is set to a level necessary for the tackiness of the adhesive to occur, the pressure is set as small as possible, and the conditions are set so that the wiring layer 805 is not completely embedded in the adhesive layer 804. By setting such conditions, compression in the subsequent pressing step is ensured.

Next, as shown in FIG. 8C, a through hole 806 is formed so as to penetrate the electrically insulating base material 802, the cover film 803, and the adhesive layer 804. Through hole 806
The wiring layer 805 is partially exposed at the bottom. The through hole 806 in which the wiring layer 805 side is closed can be easily realized by laser processing by adjusting the processing energy.

Next, as shown in FIG.
6 is filled with a conductive paste as a conductor 807 by printing. In order to realize stable filling of the conductive paste into the through-holes 806, it is preferable that printing is repeatedly performed. In this state, the surface of the conductive paste and the surface of the cover film 803 have substantially the same height.

Next, as shown in FIG. 8E, the cover film 803 on the front surface is peeled off, and a wiring material 808 is laminated on the side from which the cover film was peeled off. At this time, the conductor 80
7 protrudes from the surface of the adhesive layer 804 almost by the thickness of the cover film 803.

In this state, by applying heat and pressure by a press and bonding, a state shown in FIG. 8 (f) is obtained. At this time, the wiring layer 805 is sufficiently embedded in the adhesive layer 804, and further compresses the conductor 807. By this compression, the conductive particles in the conductive paste are firmly bonded, and the wiring layer 805, the wiring material 808 and the conductor 80
Bonding at the interface with 7 is also strong.

[0010] By this strong connection, the reliability of the connection between the wiring and the conductive paste is ensured. Subsequently, the wiring material 808 is patterned by etching, and FIG.
A double-sided wiring board as shown in (g) is completed.

Further, by repeating the steps of FIGS. 8 (a) to 8 (g), multilayering is performed as shown in FIG.
Finally, by removing the supporting base material 801, a multilayer wiring board as shown in FIG. 8I is obtained.

[0012]

However, when trying to reduce the diameter of the through-hole 806 in the above-described multilayer wiring board, in order to reduce the aspect ratio of the through-hole 806, a thin base is used as the electrically insulating base material 802. It is necessary to use a material, but in this case, a film substrate is generally used as the electrically insulating substrate.

The reason is that if the diameter of the through hole becomes smaller and the aspect ratio of the through hole 806 becomes larger, the conductor 807 becomes larger.
In addition, the filling property of the conductive paste is deteriorated, and the amount of the conductive paste taken out on the cover film side when the cover film 803 is peeled increases, so that the amount of the conductive paste in the through hole cannot be sufficiently secured. It is.

As described above, when the through-holes are reduced in order to increase the density of the multilayer wiring board, the thickness of the electrically insulating base material 802 is reduced accordingly, and the entire multilayer wiring board has flexibility. Become. As a result, the rigidity of the multilayer wiring board is impaired. In such a multilayer wiring board, the mountability of the electronic component may be deteriorated, and when a force is applied to the board after mounting the electronic component, stress is concentrated on a connection portion between the multilayer wiring substrate and the electronic component, and the connection portion has It may degrade reliability.

The present invention has been made to solve the above problems,
Provided is a multilayer wiring board which can secure rigidity even in a multilayer wiring board using a thin insulating base material for accommodating high-density wiring and can obtain extremely high connection reliability with electronic components, and a method for manufacturing the same. The purpose is to:

[0016]

In order to solve the above-mentioned problems, a multilayer wiring board according to the present invention is a multilayer wiring board in which two or more electrically insulating substrates having flexibility are laminated via an adhesive layer. The electrically insulating base material has a through hole filled with a conductor, and has wiring formed in a predetermined pattern in the adhesive layer, and the wiring layer applies a compressive force in a laminating direction. The connection is electrically connected to the conductor of the electrically insulating base material on both sides thereof, and a reinforcing layer is formed on at least one substrate surface. By providing a reinforcing layer on the surface of the multilayer wiring board, the rigidity of the board is increased, and when a force is applied to the board after mounting electronic components, stress is prevented from being concentrated on the electronic component mounting portion, and the multilayer wiring board and the electronic component are mounted. The connection reliability of the parts can be improved.

It is preferable that a through hole is provided in the reinforcing layer so as to expose at least a part of a surface wiring of the multilayer wiring board. By thus exposing the wiring also on the reinforcing layer side, connection terminals with the outside can be formed on both surfaces of the multilayer wiring board, and high-density mounting of electronic components becomes possible.

A wiring is formed on the surface of the reinforcing layer, and the inner layer wiring and the wiring on the surface of the reinforcing layer are electrically connected by a conductor filled in a through hole provided in the reinforcing layer. Is preferred. With such a configuration, it is possible to secure electrical connection with the conductor while the reinforcing layer is deformed by an external force generated on the reinforcing layer side. As a result, stress generated inside the multilayer wiring board can be suppressed.

Further, it is preferable that the elastic modulus of the reinforcing layer is smaller than the elastic modulus of the electrically insulating substrate. By selecting such material properties, the reinforcing layer is more easily deformed by an external force generated on the reinforcing layer side, and the stress generated inside the multilayer wiring board can be suppressed.

Preferably, the reinforcing layer has a coefficient of thermal expansion substantially equal to that of the electrically insulating substrate. By selecting such material properties, deformation such as warpage of the board due to a difference in the thermal expansion coefficient of the board component material during mounting of the electronic component can be suppressed, and mountability of the electronic component is improved. In addition, the deformation due to the internal stress of the substrate can be suppressed with respect to the temperature change after mounting the electronic component, and as a result, the stress generated at the connection portion of the electronic component is reduced, and the mounting reliability of the electronic component is improved.

Further, it is preferable that a diameter of the through hole provided in the reinforcing layer is larger than a diameter of the through hole provided in the electrically insulating substrate. With such a configuration, even when the reinforcing layer is deformed and strain occurs, a sufficient contact area between the conductor and the wiring can be secured, and the electrical connection reliability between the conductor and the wiring can be secured. it can.

Further, by mounting a semiconductor on the electrically insulating substrate side of the multilayer wiring board and forming a semiconductor mounting body on which a solder ball is formed on the reinforcing layer side, a semiconductor mounting excellent in mounting reliability is provided. Body can be provided.

In addition, by providing a flexible wiring board excellent in mountability of electronic components by a simple manufacturing method, the reinforcing layer of the multilayer wiring board is partially removed and the removed portion has flexibility. be able to.

Further, the reinforcing layer is made of the same material as the electrically insulating base material, and the thickness of the reinforcing layer is larger than the thickness of the electrically insulating base material, whereby the rigidity can be further increased. It is possible to stably suppress substrate deformation due to a difference in thermal expansion coefficient.

Next, a method of manufacturing a wiring board according to the present invention includes a step of forming a wiring layer in a predetermined pattern on a reinforcing layer, and an adhesive layer on both sides and through holes filled with a conductive paste. Laminating a wiring layer on one side of the electrically insulating base material and a wiring material on the other side, embedding the wiring layer in the adhesive layer by applying heat and pressure, and compressing the wiring material. Forming a layer. According to this method, since the multilayer wiring board is formed on the rigid reinforcing layer in a stacked manner, it is possible to avoid the difficulty in manufacturing a thin electrically insulating base material. In addition, in the conventional manufacturing method, the cost of the material can be reduced by eliminating the support substrate that has been discarded last.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A multilayer wiring board according to Embodiment 1 of the present invention will be described with reference to the drawings. The multilayer wiring board 101 shown in FIG. 1 is an example of a multilayer wiring board including four electric insulating layers. Although not shown in FIG. 1, as shown in FIG. 8 (i), the electric insulating layer is composed of an electric insulating base material and an adhesive layer, and the wiring is embedded in the adhesive layer. It may be. In the present embodiment, the multilayer wiring board 101 has a high wiring density and the through-hole in which the conductor 106 for connecting the layers is buried is reduced to about 30 μm to 50 μm. As the material, a film-shaped electrically insulating base material having a thickness of 10 μm to 20 μm is used. For this reason, the multilayer wiring board 101 alone has low rigidity and poor mountability of electronic components. In addition, stress is concentrated on a connection portion on which the electronic component is mounted due to an external force, thereby deteriorating mounting reliability.

Therefore, in order to provide rigidity to the multilayer wiring board, a reinforcing layer 102 is bonded to one side via an adhesive layer 103. The reinforcing layer alone has rigidity that satisfies the mountability of the electronic component. A through hole 104 is formed in the reinforcing layer 102, and the wiring 1 of the multilayer wiring board 101 is formed.
05 is partially exposed so that electrical connection can be secured from the outside. In such a configuration, the reinforcing layer can also serve as a solder resist.
Here, an example in which the adhesive layer 103 is present between the reinforcing layer 102 and the multilayer wiring board 101 is shown.
Adhesive layers may be present on both surfaces of No. 2. Also,
When the reinforcing layer 102 itself has adhesiveness, the adhesive layer 103 may not be provided.

As the reinforcing layer 102, a material having a thermal expansion coefficient substantially equal to the material used as the electrically insulating base material of the multilayer wiring board 101 is preferable. By selecting such a material, even in a multilayer wiring board configuration in which the material configuration is asymmetric in the thickness direction as shown in FIG. The mounting reliability of the electronic components on the substrate can be improved.

More preferably, if a film base made of the same material as the material used for the multilayer wiring board 101 is used as the reinforcing layer 102 and the rigidity is increased by increasing the thickness of the film base, the difference in thermal expansion coefficient may be caused. It is possible to stably suppress substrate deformation.

Next, FIG. 2 shows a state in which a semiconductor is mounted on the multilayer wiring board shown in the first embodiment and solder balls are formed on one side to form a BGA package. In FIG. 2, the same parts as those in FIG. In FIG. 2, a gold stud bump 206 is formed on the semiconductor 201 and is electrically connected to the multilayer wiring board via a conductive adhesive 207 provided on the bump. Although the mounting example by the SBB method (stud bump bonding method) in which the resin is sealed is shown, the mounting method of the semiconductor is not limited to this, and various mounting methods such as solder connection, anisotropic conductive film, and wire bonding are used. A construction method may be used.

A solder ball 204 is formed in a through hole provided in the reinforcing layer 102. The solder balls 204 are partially embedded in the reinforcing layer 102.
When this BGA package is mounted on a mother board and subjected to thermal stress such as a heat cycle, a force is applied to the solder balls due to deformation of the mother board. By holding the ball 204 and releasing the stress on the wall surface of the through hole, the stress is substantially prevented from being concentrated between the solder ball and the wiring 105 of the multilayer wiring board, and as a result, the reliability of the BGA package is improved. You can do it.

Here, the manufacturing process of the present multilayer wiring board will be described with reference to FIGS. A wiring material 303 is provided on one side of the reinforcing layer 301 with an adhesive layer 302 interposed therebetween.
FIG. 3A shows a state in which is bonded. As the reinforcing layer 301, a polyimide film, an aramid film, or the like having high heat resistance is used. The use of a film with high heat resistance ensures the heat resistance of the multilayer wiring board. Polyimide-based thermosetting adhesive, high Tg
It is preferable to use a type of epoxy adhesive from the viewpoint of heat resistance. In general, a copper foil is used as the wiring material 303, and the surface of the copper foil is roughened to improve adhesion.

Next, when a desired wiring pattern 304 is formed by pattern etching of the wiring material 303, FIG.
Is obtained. Here, the wiring material protrudes from the adhesive layer 302 by the thickness thereof.
Next, as shown in FIG. 3 (c), an adhesive layer 306 is provided on both sides of the electrically insulating base material 305 on the wiring pattern, and a film on which a cover film 307 is formed is laminated. When bonding is performed by applying heat and pressure by lamination, the state shown in FIG. 3D is obtained. It is desirable that the cover film 307 be adhered with such an adhesive strength that it can be peeled off later. In this bonding step, it is preferable that the temperature is set to a level necessary for the tackiness of the adhesive to be generated, the pressure is set as small as possible, and the conditions are set so that the wiring pattern 304 is not completely embedded in the adhesive layer 306. By setting such conditions, compression in the subsequent pressing step is ensured.

Next, as shown in FIG. 3E, a through hole 308 is formed so as to penetrate the electrically insulating base material 305, the cover film 307, and the adhesive layer 306. Through hole 308
The wiring pattern 304 is partially exposed at the bottom. This through hole processing can be easily realized by laser processing. The hole diameter of the through hole is 30 μm to 50 μm
In the case of a fine size such as m, it is preferable to use a third harmonic of an excimer laser or a YAG laser having a short laser wavelength from the viewpoint of stabilizing the processing.

Next, as shown in FIG.
8 is filled with a conductive paste as a conductor 309 by printing. In order to realize stable filling of the conductive paste into the through holes 308, it is preferable that printing is repeatedly performed. In this state, the surface of the conductive paste and the surface of the cover film 307 have substantially the same height. As the conductive paste, a material composed of an epoxy resin and conductive particles is used, and as the conductive particles, a noble metal such as copper powder, silver, and gold is used to secure electrical connection by the conductive paste. Preferred above. The use of spherical particles as the conductive particles is effective in increasing the metal density of the conductive paste.

Next, the cover film 307 is peeled off, and a wiring material 310 is further laminated thereon.
The state shown in (g) is obtained. At this time, the surface of the conductor 309 is almost completely separated from the surface of the adhesive layer 306 by the cover film 3.
It will project by the thickness of 07.

In this state, bonding is performed by applying heat and pressure to obtain the state shown in FIG. The heating and pressurizing were performed by a vacuum press, and the conditions under which both the resin of the conductive paste and the adhesive layer were cured were set, and the conditions were set at 200 ° C. for 1 hour. The use of a vacuum press suppresses bubbles from remaining between layers. At this time, the wiring pattern 304 is sufficiently embedded in the adhesive layer 306, and further compresses the conductor 309. Due to this compression, the conductive particles in the conductive paste are firmly bonded, and the bonding at the interface between the wiring pattern 304 and the wiring material 310 and the conductor 309 is also strong. This strong connection ensures the reliability of the connection between the wiring and the conductive paste.

Subsequently, the wiring material 310 is patterned by etching to complete a two-layer wiring substrate as shown in FIG.

Further, by repeating the steps shown in FIGS. 3C to 3I, multiple wiring layers are formed as shown in FIG. 3J. Finally, when a through hole 311 is formed in the reinforcing layer 301, a multilayer wiring board shown in FIG. 3K is obtained. The through hole 311 is a simple manufacturing method that is processed by laser processing. The through hole 311 exposes the wiring pattern 304 for electrical connection such as electronic component mounting, and may have a larger diameter than the through hole 308 formed in the electrically insulating base material 305. In laser processing, a carbon dioxide laser or the like having a large output is preferably used in order to penetrate the reinforcing layer 301.

Although the method for manufacturing a wiring board has been described using a four-layer wiring board as an example of the number of wiring layers, it is needless to say that the number of wiring layers is not limited to this.

A similar structure can be realized by forming a through hole in the reinforcing layer after bonding a reinforcing layer after forming a multilayer wiring board by a conventional manufacturing method. Since a multilayer wiring board is formed on a certain reinforcing layer in a stacked manner, it is possible to avoid the difficulty in manufacturing a thin electrically insulating base material. In addition, in the conventional manufacturing method, the material cost can be reduced by eliminating the support base material that is finally discarded.

(Embodiment 2) A multilayer wiring board according to Embodiment 2 will be described with reference to the drawings. Note that portions overlapping with the example shown in Embodiment 1 will be described in a simplified manner, and the same portions will be denoted by the same reference numerals. The multilayer wiring board 101 shown in FIG. 4 has a structure similar to that of the multilayer wiring board described in Embodiment 1, and the present embodiment shows an example of a multilayer wiring board having four electric insulating layers. ing. As in the first embodiment, the electric insulating layer may be formed of an electric insulating base material and an adhesive layer, and the wiring may be embedded in the adhesive layer.

The multilayer wiring board 101 is the same as the multilayer wiring board 101 shown in FIG. 1, and has a structure in which a thin electrically insulating base material is laminated via an adhesive layer. The electrical connection between the layers is realized by a fine through hole of 30 μm to 50 μm filled with a conductor.

A reinforcing layer 102 is laminated on one side of the multilayer wiring board 101 via an adhesive layer 103, and a wiring 4 is provided on the surface of the reinforcing layer 102 via an adhesive layer 402.
03 is formed. The wiring 403 and the wiring 105 in the inner layer of the multilayer wiring board are electrically connected via a conductor 401 provided in a through hole of the reinforcing layer 102. Also,
It is preferable that the wiring 105 on the surface of the reinforcing layer 102 be made only of lands by accommodating all the wirings in the multilayer wiring board 101. According to such a configuration, the reinforcing layer 102
Will also serve as a solder resist. Reinforcement layer 102
Has a rigidity that satisfies the mountability of the electronic component by itself, and improves the mountability of the electronic component on the multilayer wiring board 101 having low rigidity.

Next, FIG. 5 shows a state in which a semiconductor 501 is mounted on the multilayer wiring board shown in the second embodiment, and a solder ball 502 is formed on one side to form a BGA package. FIG. 5 shows an example of mounting by the SBB method (stud bump bonding method), but the semiconductor mounting method is not limited to this, as in the example shown in FIG.

The wiring 40 provided on the surface of the reinforcing layer 102
On 3, a solder ball 502 is formed. This BG
When the package A is mounted on a mother board and subjected to a thermal stress such as a heat cycle, a force is applied to the solder balls due to the deformation of the mother board. The concentration of stress on the connection portion between the conductor and the semiconductor in the fine through hole in the wiring board is reduced. As a result, the reliability of the BGA package can be improved.

The elastic modulus of the reinforcing layer 102 is preferably smaller than the elastic modulus of the electrically insulating substrate of the multilayer wiring board 101. By selecting a material that is easily deformed by stress as the reinforcing layer 102, the stress can be further absorbed in the reinforcing layer 102, and the reliability of the BGA package is improved. Further, by increasing the thickness of the reinforcing layer, it becomes possible to absorb stress more.

The through holes 5 provided in the reinforcing layer 102
03 is made larger than the through hole 504 provided in the multilayer wiring board 101, so that the conductor 401 and the wiring 105 can be formed.
A sufficient contact area of the wiring 505 can be ensured, and sufficient bonding strength that does not peel when the reinforcing layer 102 is deformed can be provided. As a result, the BG which does not deteriorate the connection reliability by absorbing the stress by the reinforcing layer 102 is used.
A package can be realized.

Here, the manufacturing process of the multilayer wiring board according to the present embodiment will be described with reference to FIGS. Note that portions overlapping with the manufacturing method shown in the first embodiment will be described in a simplified manner.

As shown in FIG. 6A, an adhesive layer 602 is formed on both sides of the reinforcing layer 601, and a cover film 603 is formed on this surface. When the through hole 605 is processed in this state, the state shown in FIG. 6B is obtained. The through hole 605 is processed by laser processing or the like,
It is more advantageous to improve the wiring density in the inner layer by reducing the diameter of the through hole on the side where the wiring layers are laminated in a tapered shape. The diameter of the through hole is set so that the aspect ratio is smaller than 1 in accordance with the thickness of the reinforcing layer 601. The diameter of the through hole provided in the reinforcing layer 601 is preferably set to be larger than the diameter of the through hole 606 of the electrically insulating base material 610 to be processed later, from the viewpoint of stabilizing the electrical connection.

When the conductor 604 is filled in the through hole, the state shown in FIG. 6C is obtained. Using a conductive paste as the conductor 604 and filling the conductive paste by printing with a squeegee is a method with excellent productivity. Next, when the cover film 603 is peeled off, the state shown in FIG. 6D is obtained, and the conductor 604 has a shape protruding by the thickness of the cover film 603. Here, the thickness of the cover film 603 is determined by the cover film 612 described in a later step.
It is preferably thicker than Since the diameter of the through hole 605 is large, even if the cover film is thickened, the cover film 6
The conductive paste, which is the conductor 604, is not removed to the cover film side at the time of peeling of 03, and the amount of protrusion of the conductor from the adhesive layer 602 can be sufficiently ensured.

Next, as shown in FIG.
When a copper foil is laminated and placed as 07, and heating and pressing are performed by a vacuum hot press, a state shown in FIG. 6F is obtained. Here, the conductor 604 is compressed by the amount of the protrusion, and the compression binds the conductive particles in the conductive paste, and the bonding at the interface with the wiring material 607 becomes strong. The compression at this time is performed by a fine conductor 6 described later.
However, by increasing the diameter of the through-hole, the number of contact points between the conductive particles in the conductive paste and the wiring material is increased in proportion to the square of the diameter size ratio, and the bonding strength is increased. Is compensated for and the connection reliability is secured.

Next, when the wiring material 607 is patterned by etching, the state shown in FIG. 6G is obtained. Here, an example in which the wiring material on both surfaces of the reinforcing layer is patterned has been described. However, it is sufficient if at least the wiring material on the side on which the electrically insulating base material is laminated is patterned, and the other wiring material is patterned later. It does not matter. The wiring pattern 609 protrudes from the adhesive layer 602 by the thickness thereof.

Next, as shown in FIG. 6 (h), a film in which an adhesive layer 611 and a cover film 612 are formed on both sides of an electrically insulating base material 610 is laminated on this wiring pattern, and is laminated. When heating and pressurization are performed to bond, the state shown in FIG. In this bonding process, the temperature is limited to the level necessary for the tackiness of the adhesive to occur,
It is desirable to set the pressure as small as possible as in the conventional example. By setting such conditions, compression in the subsequent pressing step is ensured.

Next, as shown in FIG. 6J, through holes 606 are formed by laser processing or the like so as to penetrate the electrically insulating base material 610, the cover film 612, and the adhesive layer 611. The diameter of the through hole is 30 μm to 50 μm, which is smaller than that of the aforementioned through hole 605. Next, as shown in FIG. 6K, a conductive paste is filled into the through hole 606 as a conductor 608 by printing. Next, the cover film 612 is peeled off, and the wiring material 61 is further laid thereon.
When 3 are stacked, the state shown in FIG. 6 (l) is obtained. In this state, bonding is performed by heating and pressing to obtain the state shown in FIG. The heating and pressurization is performed by a vacuum press, so that the wiring pattern 609 is sufficiently embedded in the adhesive layer 611, and the conductor 608 is further compressed. By this compression, the conductive particles in the conductive paste are firmly bonded, and the bonding at the interface between the wiring pattern 609 and the wiring material 613 and the conductor 608 is also strong. This strong connection ensures the reliability of the connection between the wiring and the conductive paste.

Subsequently, the wiring material 613 is patterned by etching to obtain a state as shown in FIG. Further, by repeating the steps of FIGS. 6H to 6N, a multilayer wiring board as shown in FIG. 6O can be obtained. Needless to say, the number of wiring layers of the multilayer wiring board is not limited to this.

Further, as shown in FIG.
By adopting a configuration in which the reinforcing layer 102 on one side is partially removed, the bent portion 701 can be formed in a part of the multilayer wiring board, and a flexible wiring board with excellent mounting reliability can be realized. If the bent portion 701 of the reinforcing layer 102 is removed by laser processing in the through hole forming step, a manufacturing method with excellent productivity can be provided.

The same effect can be obtained by forming a slit-shaped process on the reinforcing layer 102 at the bent portion 701 to form a bent portion. FIG. 7 shows an example in which a bent wiring board is formed based on the configuration of the multilayer wiring board shown in FIG.
The same effect can be obtained by removing the reinforcing layer of the multilayer wiring board and forming the bent portion.

[0060]

As is apparent from the above description, the multilayer wiring board of the present invention is a multilayer wiring board in which two or more flexible electrically insulating substrates are laminated via an adhesive layer.
The electrically insulating base material has a through hole filled with a conductor, has wiring formed in a predetermined pattern in the adhesive layer, and the wiring layer has been given a compressive force in a laminating direction. Thereby, the conductive layer is electrically connected to the conductor of the electrically insulating substrate on both sides thereof, and a reinforcing layer is formed on at least one substrate surface. By providing a reinforcing layer on the surface of the multilayer wiring board, the rigidity of the board is increased, and when a force is applied to the board after mounting electronic components, stress is prevented from being concentrated on the electronic component mounting portion, and the multilayer wiring board and the electronic component are mounted. The connection reliability of the parts can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a multilayer wiring board according to a first embodiment;

FIG. 2 is a sectional view showing a semiconductor package using the multilayer wiring board according to the first embodiment;

FIG. 3 is a cross-sectional view showing a main step of the method for manufacturing a multilayer wiring board according to the first embodiment;

FIG. 4 is a sectional view showing a configuration of a multilayer wiring board according to a second embodiment;

FIG. 5 is a sectional view showing a semiconductor package using the multilayer wiring board according to the second embodiment;

FIG. 6 is a sectional view showing the manufacturing method of the multilayer wiring board according to the second embodiment for each of main steps;

FIG. 7 is a cross-sectional view illustrating a configuration of a bent wiring board of the present invention.

FIG. 8 is a cross-sectional view illustrating a conventional method for manufacturing a multilayer wiring board for each of main steps.

[Explanation of symbols]

101 multilayer wiring board 102,301,601 reinforcing layer 103,302,306,402,602,611,8
04 adhesive layer 104,308,311,503,504,605,6
06,806 Through-hole 105,403,505 Wiring 106,309,401,604,608,807 Conductor 201,501 Semiconductor 204,502 Solder ball 206 Stud bump 303,310,607,613,808 Wiring material 304 Wiring pattern 305, 610, 802 Electrically insulating substrate 307, 603, 612, 803 Cover film 701 Bent portion 801 Supporting substrate 805 Wiring layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Daizo Ando 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.F-term (reference) DD12 DD32 EE02 EE33 FF18

Claims (10)

[Claims] 1. A multilayer wiring board in which two or more flexible electrically insulating substrates are laminated via an adhesive layer, wherein the electrically insulating substrate has a through hole filled with a conductor. ,
The adhesive layer has wiring formed in a predetermined pattern, and the wiring layer is electrically connected to the conductors of the electrically insulating base material on both sides by applying a compressive force in a laminating direction. Wherein a reinforcing layer is formed on at least one substrate surface. 2. The multilayer wiring board according to claim 1, wherein a through-hole is provided in the reinforcing layer so as to expose at least a part of a surface wiring of the multilayer wiring board. 3. A wiring is formed on the surface of the reinforcing layer, and the inner wiring and the wiring on the surface of the reinforcing layer are electrically connected by a conductor filled in a through hole provided in the reinforcing layer. The multilayer wiring board according to claim 1, wherein: 4. The multilayer wiring board according to claim 1, wherein an elastic modulus of said reinforcing layer is smaller than an elastic modulus of said electrically insulating base material. 5. The multilayer wiring board according to claim 1, wherein the reinforcing layer has a coefficient of thermal expansion substantially equal to that of the electrically insulating substrate. 6. The multilayer wiring board according to claim 2, wherein a diameter of the through hole provided in the reinforcing layer is larger than a diameter of the through hole provided in the electrically insulating substrate. 7. A semiconductor package comprising a multilayer wiring board according to claim 1, wherein a semiconductor is mounted on the electrically insulating base material side, and a solder ball is formed on the reinforcing layer side. 8. A bent wiring board, wherein the reinforcing layer of the multilayer wiring board according to claim 1 is partially removed, and the removed portion has flexibility. 9. The method according to claim 1, wherein the reinforcing layer is made of the same material as the electrically insulating base material, and the thickness of the reinforcing layer is larger than the thickness of the electrically insulating base material. Multilayer wiring board. 10. A step of forming a wiring layer in a predetermined pattern on a reinforcing layer, and a wiring layer on one of an electrically insulating base material having an adhesive layer on both sides and a through hole filled with a conductive paste. A multilayer formed by repeating a step of laminating a wiring material on the other side, a step of embedding the wiring layer in the adhesive layer by applying heat and pressure, and a step of patterning the wiring material to form a wiring layer. Manufacturing method of wiring board.