JPH10303553A - Manufacture for printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a printed board with a small warpage by sandwiching between boards at least one prepreg having through openings for forming hollow spaces at the positions corresponding to the parts where the boards are opposed to each other when thermosetting resin is heated and pressed and is fluidized. SOLUTION: A first board 11a, a second board 11b and a prepreg 20 sandwiched therebetween are laminated such that a conductive pattern 14 having cured resin 15 buried in the spaces touches the prepreg 20 and then the prepreg 20 is heated and pressed to fluidize and cure the thermosetting resin in the prepreg 20. This integrates the first board 11a, the second board 11b and the prepreg 20 and forms hollow spaces 25 therein. The part of the board corresponding to the hollow spaces 25 are hard to shrink and hence the absolute amount of the shrinkage of the first board 11a and that of the second board 11b become small and the difference between them also becomes small, which can form a printed board with a small warpage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board used for electric and electronic equipment.

[0002]

2. Description of the Related Art A multilayer printed wiring board having a plurality of conductor layers has been used as a printed wiring board for mounting electronic components and semiconductor devices. As a method of manufacturing this multilayer printed wiring board, for example, as shown in FIG. 5 (a), there is a penetrated substrate hole 33, and the entire surface of one surface excluding the substrate hole 33 is made of metal. An organic first substrate 31a having a layer 32, and an organic second substrate 31b having an inner layer conductor pattern 34 on one surface and a metal layer 32 on the entire surface on the other surface; A prepreg 40 manufactured by impregnating a base material such as a glass cloth with a thermosetting resin such as an epoxy resin is used. In the prepreg 40, a portion corresponding to the substrate hole 33 formed in the first substrate 31a has a penetrated prepreg hole 42, and the second substrate 31b has the aforementioned substrate hole 3
The portion corresponding to No. 3 has a conductor pattern 34 for the inner layer.

Then, the first substrate 31a is placed such that the inner layer conductor pattern 34 is in contact with the prepreg 40.
After the prepreg 40 is interposed between the second substrate 31b and the prepreg 40, the thermosetting resin in the prepreg 40 is heated and pressurized so that the recess between the conductor patterns 34 is filled with the thermosetting resin. Filling, as shown in FIG.
A multilayer laminate having a concave portion 37 with the conductive pattern 34 exposed on the bottom surface is manufactured.

[0005] Next, as shown in FIG. 5 (c), after punching a hole in the laminated board, plating is performed, and through-hole plating for conducting the inner conductor pattern 34 and the outer metal layer (32) to the hole is performed. A printed wiring board is manufactured by forming a film 38 and then etching an outer metal layer to form a conductor pattern 39 for the outer layer.

When a prepreg is used in manufacturing a laminated board, the resin in the prepreg exhibits a behavior in which the viscosity decreases as soon as it is heated and the resin flows, and when further heated, the resin hardens and the resin does not flow. Therefore, it is easy to handle because it is in a solid state in handling at the time of lamination, and it has a certain degree of fluidity during heating and pressing, so it can be adhered even if it has some irregularities. Have been.

However, when manufactured by this method, FIG.
As shown in (c), the thermosetting resin 45 flows out into the portion of the conductor pattern 34 exposed on the bottom surface of the concave portion 37 and covers the surface, and when an electronic component or the like is mounted on the conductor pattern 34, the connection reliability is reduced. There was a problem that the property is low.

For this reason, as shown in FIG. 6, a thermosetting resin is applied between the conductor patterns 34 of the portion of the inner layer conductor pattern 34 that is to be brought into contact with the prepreg 40, on the surface of the second substrate 31b. After applying, cure
The space between the conductor patterns 34 is filled with a cured resin 35, and then
By laminating using a prepreg 40 in which the thermosetting resin is less likely to flow than the prepreg used in the above method,
A method of making it difficult for the thermosetting resin to flow into the portion of the conductor pattern 34 that is to be exposed on the bottom surface of the concave portion when heated and pressed is being studied.

The laminate obtained by heating and pressurizing after laminating the prepreg between the substrates is generally warped because the first substrate 31a and the second substrate 31b generally have different shrinkage amounts. There is also a problem that a printed wiring board manufactured using a laminated board having a large warp tends to have a large warp.

Therefore, a method for manufacturing a printed wiring board is described in which a prepreg is sandwiched between substrates and laminated and then heated and pressed to produce a printed wiring board with a small warpage. It has been demanded.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a prepreg in which a thermosetting resin is impregnated into a glass cloth and a plurality of sheets. A method for producing a printed wiring board, comprising: using an organic substrate, laminating a prepreg between substrates, and then heating and applying pressure, wherein a printed wiring board with a small warpage is obtained. It is to provide a manufacturing method.

[0011]

According to a first aspect of the present invention, there is provided a method for manufacturing a printed wiring board, comprising: a prepreg in which a thermosetting resin is impregnated in a glass cloth; Using a plurality of organic substrates having a plurality of conductor patterns embedded in the cured product on the surface thereof, sandwich the prepreg between the substrates so that the conductor pattern embedded in the cured resin is in contact with the prepreg. After lamination,
In the method of manufacturing a printed wiring board manufactured by heating and pressing, the prepreg sandwiched between the substrates is heated and pressed at a position corresponding to a portion where the substrate is opposed to at least one of the sandwiched prepregs. When the thermosetting resin flows, the prepreg has a penetrating opening having a size to form a cavity.

The term "part facing the substrate" in the present invention means that when a hole is formed in the substrate, the hole is not included.

According to a second aspect of the present invention, in the method for manufacturing a printed wiring board according to the first aspect, all the prepregs sandwiched between the substrates have the opening. And

According to a third aspect of the present invention, there is provided a method of manufacturing a printed wiring board according to the first or second aspect, wherein the prepreg sandwiched between the substrates comprises:
The prepreg is characterized in that the prepreg is provided with openings so that the openings are exposed in all the cross sections in the X and Y directions of the prepreg.

When the thermosetting resin in the prepreg is cured by heating, the thermosetting resin cures and shrinks, and the shrinkage also shrinks the substrates laminated on both sides of the prepreg.
Therefore, if the compressive strength between the substrates laminated on both sides of the prepreg is different, the contraction amount between the substrates is different, and it is considered that the difference causes the bending to the side having the larger contraction amount and warpage. However, according to the present invention, since the cavity is formed in the printed wiring board, the portion of the substrate corresponding to the cavity is unlikely to shrink, and the absolute value of the amount of shrinkage between the substrates is reduced, and the difference is also small. And warpage is reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a printed wiring board according to the present invention will be described with reference to the drawings. 1A and 1B are diagrams showing an embodiment of a method for manufacturing a printed wiring board according to the present invention, wherein FIG. 1A is a perspective view illustrating lamination, FIG. 1B is a cross-sectional view illustrating lamination, and FIG. FIG. 3 is a cross-sectional view illustrating a state after heating. FIG. 2 also shows a method of manufacturing a printed wiring board according to the present invention.
It is a figure which shows one Embodiment, (a) is the top view explaining before heating, (b) is the figure fractured | ruptured and shown in the plane direction explaining after heating. FIG. 3 is a diagram for explaining the warpage. FIG. 4 is a plan view showing a modification of the embodiment of the method for manufacturing a printed wiring board according to the present invention.

One embodiment of the method for manufacturing a printed wiring board according to the present invention has a penetrated substrate hole 13 as shown in FIGS.
A copper metal layer 12 is formed on the entire surface on one side except the portion 3.
And an organic first substrate 11a having
An organic second substrate 11b having a plurality of inner layer conductor patterns 14 filled with a cured resin material 15 therebetween and a copper metal layer 12 on the entire other surface;
The prepreg 20 is used.

Then, one prepreg 20 is sandwiched between the first substrate 11a and the second substrate 11b such that the conductor pattern 14 filled with the cured resin 15 is on the side in contact with the prepreg 20. After lamination, the thermosetting resin in the prepreg 20 is heated and pressurized to fluidize and then harden, and the first substrate 11a, the second substrate 11b, and the prepreg 20 are integrated, and FIG. A multilayer laminate having a cavity 25 therein is manufactured as shown in FIG.

Next, although not shown, the laminated plate is perforated as necessary, and then a plating process is performed to form a through-hole plating film for conducting the inner conductor pattern and the outer metal layer in the perforated holes. The printed wiring board is manufactured by processing such as etching the outer metal layer to form a conductor pattern for the outer layer.

As shown in FIG. 2A, the prepreg 20 to be used has a penetrating opening 21 at a portion where the hollow portion (25) is to be formed. As shown in FIG. 2B, the size of the cavity 21 is such that a cavity 25 is formed when the thermosetting resin 23 flows by heating and pressing. In addition, FIG.
Is a plan view illustrating the prepreg 20 before heating,
(B) is a diagram showing a portion corresponding to the prepreg 20 after heating and pressurization, which is cut away in a plane direction.

When the thermosetting resin 23 in the prepreg 20 is cured by heating, the thermosetting resin 23 cures and contracts, and the contraction also causes the first substrate and the second substrate to contract. Therefore, if the compressive strengths of the first substrate and the second substrate are different, the amount of contraction of the first substrate and the second substrate is different, and due to this difference, as shown in FIG. It is considered that the end of the laminate 10 bends and warpage S occurs. However, if a cavity is formed in a laminated plate by using a prepreg having an opening, the portion of the substrate corresponding to the cavity is unlikely to shrink, so the absolute amount of shrinkage of the first substrate and the second substrate is reduced. The values become smaller and the difference becomes smaller. Therefore, the radius of curvature d at which the end of the laminated plate 10 bends is reduced, and the warpage S is reduced.
Also, the printed wiring board obtained by using the laminated board having a small warpage S has a small warpage. FIG. 3 (a)
Is a diagram illustrating a laminated plate 10 having a hollow portion,
(B) is a figure explaining the conventional laminated board 10 which does not have a cavity part.

The shape of the opening 21 is not limited to a substantially spiral shape as shown in FIG. 2A, and the opening 21 is provided between the openings 21 as shown in FIG. 4 (b), an opening 21 is provided between the prepregs 20 to form a square meander, as shown in FIG. 4 (b), or as shown in FIG. 4 (c). By forming the meandering in both the X direction (horizontal direction in the figure) and the Y direction (vertical direction in the figure) of the prepreg 20, the prepreg 2
0, the prepreg 20 in which the openings 21 are disposed so that the openings 21 are exposed in all the cross sections in the X and Y directions.
4 (d), a prepreg 20 provided with an opening 21 at the center and formed in the shape of a mouth, or a prepreg 20 disposed at four corners as shown in FIG. 4 (e). And the like. The prepreg 2 shown in FIG.
In the case of the prepreg 20 in which the openings 21 are arranged so that the openings 21 are exposed in all the cross sections in the X direction and the Y direction of 0, both the shrinkage amounts in the X direction and the Y direction can be reduced. Therefore, the warpage is particularly small, which is preferable. In addition, in the case of the prepreg 20 having a meandering shape or the prepreg 20 having a mouth shape shown in FIGS. 4B, 4C, and 4D, the prepreg 20 is connected to one sheet. Is excellent in workability when laminating with a substrate.

The opening 21 of the prepreg 20 only needs to be provided at a position corresponding to a portion where the first substrate 11a and the second substrate 11b face each other.
A portion corresponding to the penetrating substrate hole 13 formed in the first substrate 11a shown in FIG. 1B may or may not have a penetrating hole. In the prepreg 20 at a portion corresponding to the substrate hole 13,
2 and the conductor pattern 14 for the inner layer is formed on the portion of the second substrate 11b corresponding to the substrate hole 33, as shown in FIG. Since a recess 17 is formed on the bottom of the laminated board obtained by pressing the conductive pattern 14 so that the conductive pattern 14 is exposed, the printed wiring board obtained by using this laminated board has a reduced number of conductive patterns 14 on which electronic components and the like are mounted. It is possible to increase. The prepreg holes 22 formed in portions corresponding to the substrate holes 13 are formed.
Are not included in the opening 21 formed at a position corresponding to the portion where the substrates 11a and 11b face each other.

In the above embodiment, the first substrate 11
The embodiment in which one prepreg 20 is sandwiched between the first prepreg 20 and the second substrate 11b has been described.
0 is not limited to one sheet, and a plurality of sheets may be inserted. In the case where a plurality of prepregs 20 are sandwiched, it is preferable that all the prepregs 20 have the opening 21 because the warp is particularly small, but it is preferable that at least one of the sandwiched prepregs 20 has the opening 21. If this occurs, the warpage will be small.

In the above embodiment, the first substrate 11
Although the embodiment using two substrates a and the second substrate 11b has been described, the number of substrates used is not limited to two, and the substrate is formed to penetrate outside the first substrate 11a. An organic substrate having a substrate hole 13 is placed between a prepreg 20
May be laminated with the second substrate 11b
An organic substrate may be laminated on the outside with the prepreg 20 interposed therebetween. Also in this case, if at least one of the sandwiched prepregs 20 has the opening 21, the warpage is smaller than in the case where none of the prepregs 20 has the opening 21.

The substrates 11a, 11b used in the present invention
Means that at least one of them has a resin cured product 15
An organic plate having on its surface a plurality of conductive patterns 14 buried with a resin, and an organic plate having on its surface a plurality of conductive patterns 14 buried with a cured resin 15 is, for example, glass or the like. Inorganic fiber and polyester,
Substrates of organic fiber cloth such as polyamide and cotton, paper and the like are bonded with a thermosetting resin and a metal foil is stretched on one or both sides, or one or both sides of a sheet of the thermosetting resin alone The surface of the metal foil is etched by using a plate or the like on which a metal foil is stretched to form a conductor pattern 14, and then a thermosetting resin is applied between the conductor patterns 14, and then the thermosetting resin is applied. To cure the conductor pattern 14
After filling the space with a cured resin material 15 and a similar plate on which a metal foil is not stretched, metal plating is performed to form a conductor pattern 14, and then a thermosetting resin is applied between the conductor patterns 14, Next, the thermosetting resin is cured to fill the space between the conductor patterns 14 with the cured resin 15.

In the case where an organic substrate having no conductive pattern 14 on its surface is used, the substrate may be a plate obtained by bonding the above-mentioned base material with a thermosetting resin or the like, or a sheet of the thermosetting resin alone. No.

As the thermosetting resin, thermosetting resins such as epoxy resin type, phenolic resin type, polyimide resin type, unsaturated polyester resin type and polyphenylene ether resin type, and inorganic filling of these thermosetting resins. A resin composition containing a material and the like is included. The substrate 11a,
11b... And the conductive pattern 14
The thermosetting resin used for the cured resin 15 filling the space may be the same or different.

The substrates 11a and 11b used in the present invention
··· may have a conductor pattern or a hole formed by forming a metal film on the wall surface of the conductor pattern. Further, the surfaces of the substrates 11a, 11b,... Used in the present invention that are not in contact with the prepreg 20 may have a metal layer, and an organic insulating portion may be exposed. In the above embodiment, the embodiment in which the substrate hole 13 is provided in the first substrate 11a has been described, but the substrate hole 13 may not be provided.

The metal forming the conductive pattern 14 is preferably copper or a metal having a metal film such as a nickel film formed on the surface of copper from the viewpoint of electrical reliability.

The prepreg 20 used in the present invention includes:
Substrates of inorganic fibers such as glass, organic fibers such as polyester, polyamide and cotton, and substrates such as paper are impregnated with the above-mentioned thermosetting resin and then semi-cured to form a sheet. The thermosetting resin used for the prepreg 20 may be a thermosetting resin used for the substrates 11a, 11b,.
May be the same as or different from the thermosetting resin used for the resin. Examples of a method for forming the opening 21 in the prepreg 20 include a method of forming the opening 21 by cutting by router processing, die punching, or the like.

The substrates 11a, 11b... And the prepreg 20
After laminating, the heating and pressurizing conditions may be appropriately adjusted under the condition where the thermosetting resin in the prepreg 20 is cured, and the heating and pressurizing may be performed. Since the warpage of the board and the printed wiring board tends to increase, the prepreg 2 and the substrates 11a, 11b.
It is preferable to apply the pressure as low as possible within a range where 0 can be integrated.

[0033]

The method for manufacturing a printed wiring board according to the present invention is characterized in that a prepreg sandwiched between substrates is heated and pressurized at a position corresponding to a portion where the substrate is opposed to when the thermosetting resin flows. Since a prepreg having a penetrating opening having a size to form a cavity is used, a printed wiring board with small warpage can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a method for manufacturing a printed wiring board according to the present invention, wherein (a) is a perspective view illustrating lamination, (b) is a cross-sectional view illustrating lamination, and (c). () Is a cross-sectional view for explaining after heating.

FIGS. 2A and 2B are views showing one embodiment of a method for manufacturing a printed wiring board according to the present invention, wherein FIG. 2A is a plan view illustrating a state before heating, and FIG. FIG.

FIG. 3 is a diagram illustrating warpage.

FIG. 4 is a plan view showing a modification of the embodiment of the method for manufacturing a printed wiring board according to the present invention.

FIG. 5 is a process chart illustrating a conventional method for manufacturing a printed wiring board.

FIG. 6 is a cross-sectional view illustrating a part of the steps of another conventional method for manufacturing a printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Laminated board 11a, 11b, 31a, 31b Substrate 12, 32 Metal layer 13, 33 Substrate hole 14, 34, 39 Conductive pattern 15, 35 Resin hardened material 17, 37 Depression 20, 40 Prepreg 21 Opening 22, 42 Prepreg hole 23 Thermosetting Resin 25 Cavity 33 Board Hole 38 Through Hole Plating Film 39 Conductor Pattern 45 Thermosetting Resin

Continued on front page (72) Inventor Tomoki Takazoe 1048 Odakadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd.

Claims (3)

[Claims] 1. A prepreg in which a thermosetting resin is impregnated in a glass cloth, and at least one of the prepregs has a plurality of organic substrates having a plurality of conductive patterns filled with a cured resin on the surface. In the method for manufacturing a printed wiring board, a prepreg is sandwiched between substrates and laminated, and then heated and pressed, so that the conductive pattern filled with the cured resin is in contact with the prepreg. The prepreg sandwiched between the substrates has at least one of the sandwiched prepregs at a position corresponding to a portion where the substrate faces,
A method for manufacturing a printed wiring board, comprising: a prepreg having a penetrating opening having a size to form a cavity when a thermosetting resin flows under heat and pressure. 2. The method according to claim 1, wherein all the prepregs sandwiched between the substrates have the opening. 3. The prepreg sandwiched between the substrates is a prepreg provided with openings such that the openings are exposed in all cross sections of the prepreg in the X and Y directions. The method for producing a printed wiring board according to claim 1 or 2.