JPH10303556A - Manufacture of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a printed wiring board wherein two boards and a prepreg formed by impregnating glass cloth with thermosetting resin are used, the prepreg is sandwiched between the boards and laminated, heated and pressed, and a printed wiring board of small warp can be obtained. SOLUTION: In the method for laminating boards 11a, 11b, the two boards are so laminated that the directions L1, L2 wherein the coefficients of linear expansion of the respective boards are large intersect with each other, In other case, two boards are so laminated that the coefficient of linear expansion of one board in the X direction is larger than that of the other board in the X direction, and that the coefficient of linear expansion of the one board in the Y direction is larger than that of the other board in the Y direction.

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. 6A, an organic first substrate 31a having a metal layer 32 on one entire surface and an inner layer Conductor pattern 3
And a prepreg 35 made by impregnating a base material such as a glass cloth with a thermosetting resin such as an epoxy resin and a thermosetting resin such as an epoxy resin. Is used.

After the prepreg 35 is laminated between the first substrate 31a and the second substrate 31b such that the conductor pattern 33 for the inner layer is in contact with the prepreg 35,
By heating and pressurizing to flow the thermosetting resin in the prepreg 35, the concave portions between the conductor patterns 33 are integrated while being filled with the thermosetting resin, thereby forming a multilayered structure as shown in FIG. Manufacture laminates.

[0006] Next, as shown in FIG. 6 (c), a hole is formed in the laminated plate, and then a plating process is performed to form a through hole for conducting the inner conductor pattern 33 and the outer metal layer (32) to the hole. A plating film 37 is formed, and then the outer metal layer is etched to form a conductor pattern 38 for the outer layer.
The printed wiring board is manufactured by forming.

However, as shown in FIG. 6C, the printed wiring board manufactured by this method has a conductor pattern 3 for the inner layer.
In some cases, bubbles 39 may remain between the layers 3, and there is a problem that heat resistance to moisture absorption and electrical reliability are low.

Therefore, as shown in FIG. 7, the conductor patterns 33 for the inner layer on the surface of the second substrate 31b.
In the meantime, a thermosetting resin is applied and then cured, and the space between the conductor patterns 33, 33 is filled with a cured resin 34.
During this time, the conductor pattern 3 filled with the resin cured material 34
A method is considered in which the air bubbles (39) are less likely to remain between the conductor patterns 33, 33 for the inner layer of the obtained printed wiring board by laminating the layers 3 and 33 so as to be in contact with the prepreg 35.

The substrates 31a and 31b are made of a glass cloth and a cured resin, and after laminating a required number of prepregs manufactured by impregnating a glass cloth with a thermosetting resin such as an epoxy resin, the one side thereof is formed. Alternatively, it is generally manufactured by laminating a metal foil such as a copper foil on both sides, and then heating and pressing to cure the thermosetting resin in the prepreg.

[0008] The glass cloth used in the production of these substrates and prepregs is produced by a method in which the weft passes between the warp yarns. When a plurality of substrates are used and a plurality of substrates are used, a laminated board is manufactured by laminating the glass cloth so that all the warp directions are aligned.

A laminate obtained by heating and pressing after laminating a prepreg between substrates is likely to have a large warp, and a printed wiring board manufactured using the large warp laminate is also warped. There is a problem that it is easy to grow.

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.

[0011]

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 substrate made of glass cloth and a cured resin, and a thermosetting resin. A method for manufacturing a printed wiring board in which a prepreg impregnated in a glass cloth is used and laminated by sandwiching the prepreg between substrates, and then heating and pressing are performed. An object of the present invention is to provide a method for manufacturing a wiring board.

[0012]

According to a first aspect of the present invention, there is provided a method for manufacturing a printed wiring board, wherein at least one of the printed wiring boards has a plurality of conductor patterns filled with a cured resin on the surface. Using two substrates made of a glass cloth and a cured resin, and a prepreg in which a thermosetting resin is impregnated in a glass cloth, the conductor pattern filled with the cured resin is in contact with the prepreg. As described above, in a method for manufacturing a printed wiring board manufactured by heating and pressing after laminating a prepreg between substrates, the method of laminating the substrates is such that two substrates have large linear expansion coefficients. The method is characterized in that the layers are stacked so that the directions intersect.

According to a second aspect of the present invention, there is provided a method for manufacturing a printed wiring board according to the first aspect, wherein each of the substrates has an intersection angle at which a direction having a large coefficient of linear expansion intersects. The angle is 30 to 90 degrees.

According to a third aspect of the present invention, there is provided a method for manufacturing a printed wiring board, wherein at least one of the printed wiring boards has a plurality of conductive patterns on its surface, the conductive patterns being filled with a cured resin.
Using two substrates composed of a glass cloth and a cured resin, and a prepreg in which a thermosetting resin is impregnated in a glass cloth, so that the conductor pattern filled with the cured resin is on the side in contact with the prepreg. In a method of manufacturing a printed wiring board manufactured by laminating a prepreg between substrates and then heating and applying pressure, the method of laminating the substrates is such that the coefficient of linear expansion of one substrate in the X direction is determined by the other substrate. Are laminated so as to be larger than the linear expansion coefficient in the X direction, and the linear expansion coefficient of the one substrate in the Y direction, which is a direction orthogonal to the X direction, is calculated from the linear expansion coefficient of the other substrate in the Y direction. , Characterized in that it is a method of laminating so as to be large.

When two substrates are stacked and heated and pressed, each substrate expands due to the heating. Since the amount of expansion is proportional to the magnitude of the linear expansion coefficient of each side, when the thermosetting resin in the prepreg cures, each side of each substrate is adhered in a state of a different amount of expansion. Integrate. In addition, since it is pressurized at this time, it is formed into a planar shape. Therefore, it is considered that, after cooling and returning to normal pressure, the side of the laminate having a large linear expansion coefficient shrinks more and the side is curved, so that warpage occurs.

However, according to the present invention, the printed wiring board obtained has a shape in which all sides are curved and which is warped in a saddle shape,
The printed wiring board has a shape that is warped into a bowl shape and has a shape corrected to a shape close to a planar shape.

[0017]

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. FIG. 1 is a view showing one embodiment of a method for manufacturing a printed wiring board according to claim 1 of the present invention, (a) is a perspective view for explaining lamination,
(B) is a cross-sectional view for explaining lamination, and (c) is a cross-sectional view for explaining after heating and pressing. 2A and 2B are diagrams showing another embodiment of the method for manufacturing a printed wiring board according to claim 1 of the present invention, wherein FIG. 2A is a perspective view illustrating lamination, and FIG. 2B is a perspective view illustrating warpage. FIG. 3A and 3B are views showing one embodiment of a method for manufacturing a printed wiring board according to claim 3 of the present invention, wherein FIG. 3A is a perspective view illustrating lamination, and FIG. 3B is a perspective view illustrating warpage. It is. 4A and 4B are views showing a conventional method for manufacturing a printed wiring board, wherein FIG. 4A is a perspective view illustrating lamination, and FIG. 4B is a perspective view illustrating warpage. FIGS. 5A and 5B are diagrams illustrating warpage, FIG. 5A is a diagram illustrating a printed wiring board according to claim 1 of the present invention, and FIG. 5B is a diagram illustrating a conventional printed wiring board.

[Method of Manufacturing Printed Wiring Board According to Claims 1 and 2 of the Present Invention] One embodiment of the method of manufacturing a printed wiring board according to claim 1 of the present invention is shown in FIGS.
As shown in (b), a first substrate 11a having a metal layer 12 on one entire surface and a cured resin 1 between one surface are provided.
4, a second substrate 11b having a plurality of inner layer conductor patterns 13 and a metal layer 12 on the entire other surface, and a prepreg manufactured by impregnating a thermosetting resin into a glass cloth. 15 is used.

Then, one prepreg is placed between the first substrate 11a and the second substrate 11b such that the conductor pattern 13 for the inner layer filled with the cured resin 14 is on the side in contact with the prepreg 15. 15 after laminating, heating and
Pressing is performed to integrate as shown in FIG. 1 (c) to produce a multilayer laminate 10 having a conductor pattern 13 in the inner layer and a metal layer 12 in the outer layer.

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

As shown in FIG. 1A, the two substrates 11a and 11b to be laminated have a direction L1 in which the linear expansion coefficient of the first substrate 11a is large and a linear expansion coefficient L2 of the second substrate 11b. Are stacked so that the directions L2 with the larger crosses 90 degrees. Therefore, the laminate obtained by heating and pressing has a small warpage. Also, the printed wiring board obtained by using the laminated board having a small warp also has a small warp.

In the conventional case where the substrates are laminated so that the warp directions of the glass cloth are all aligned, as shown in FIG. 4A, the direction L1 of the first substrate 11a where the coefficient of linear expansion is large is L1.
And the direction L2 where the coefficient of linear expansion of the second substrate 11b is large is
Generally in the same direction. Then, the two substrates 11
a, 11b are set in the directions L1,
After laminating so that L2 is in the same direction, the laminated board 10 obtained by heating and pressurizing and the printed wiring board obtained by using the laminated board 10 have one direction as shown in FIG. The curvature of the two sides is small, but the curvature of the two sides in the other direction is particularly large, resulting in a shape that is warped to a semi-cylindrical shape.

This is because the first substrate 11a and the second substrate 1
When the substrates 1a and 11b are heated and pressurized after laminating the substrates 1b, the substrates 11a and 11b expand due to the heating. This expansion is
When the thermosetting resin in the prepreg 15 is cured, each side of each of the substrates 11a and 11b is adhered while being in a state of a different expansion amount and is integrally formed because the linear expansion coefficient is proportional to the magnitude of the linear expansion coefficient of each side. Become In addition, since it is pressurized at this time, it is formed into a planar shape. Therefore, it is considered that, after cooling and returning to normal pressure, the side of the laminate 10 having a large coefficient of linear expansion contracts more and the side is curved, so that warpage occurs.

Then, as shown in FIG. 4A, the linear expansion coefficient α1x in the X direction of the first substrate 11a is larger than the linear expansion coefficient α1y in the Y direction (direction orthogonal to the X direction) (α1x> α
1y), the linear expansion coefficient α2x in the X direction of the second substrate 11b is Y
When the layers are stacked so as to be larger than the linear expansion coefficient α2y in the direction (α2x> α2y), the contraction amounts of the sides corresponding to the large linear expansion coefficients α1x and α2x are particularly large, and therefore, as shown in FIG. It has a semi-cylindrical shape.

However, as shown in FIG. 2A, the linear expansion coefficient α1y in the Y direction of the first substrate 11a is larger than the linear expansion coefficient α1x in the X direction (α1y> α1x), and the second substrate 11b Are laminated such that the linear expansion coefficient α2x in the X direction is larger than the linear expansion coefficient α2y in the Y direction (α2x> α2y).
After laminating the substrates 11a and 11b such that the directions L1 and L2 of large linear expansion coefficients intersect, heating and
The laminated board 10 obtained by pressing and the printed wiring board obtained by using the laminated board 10 are averaged because the other substrate is small even if the contraction amount of one substrate is large, and FIG. As shown in b), all four sides are curved and have a shape that is warped in a saddle shape (also called a reciprocal curvature). Therefore, as shown in FIG. 5 (b), when curved to the semi-cylindrical shape manufactured by the conventional manufacturing method, the greatly curved side becomes a shape close to a planar shape as shown in FIG. 5 (a). The shape becomes a corrected shape, and the warpage S becomes smaller as compared with the conventional method.

As a method of laminating the two substrates 11a and 11b such that the directions of large coefficients of linear expansion intersect with each other, the magnitude of the coefficient of linear expansion of the substrate is generally determined by forming the insulating portion of the substrate. Since the influence of the glass cloth is large, such as the thickness of the glass cloth to be formed, the number of yarns in the glass cloth, the strength of the yarn, and the amount of shrinkage of the weave of the glass cloth, these are appropriately adjusted, and the line of each substrate is adjusted. It is sufficient to make the directions having a large expansion coefficient intersect, but it is also possible to make them intersect by using substrates having the same linear expansion coefficient and stacking them without aligning the direction of the linear expansion coefficient.

The coefficient of linear expansion of the present invention is not limited to the coefficient of linear expansion of only the insulating portion of the substrate. The coefficient of linear expansion of the entire substrate including the conductor pattern 13, the cured resin 14, and the metal layer 12 is determined. It indicates the direction in which the rate is large. If there is a difference in the formation density of the conductor patterns 13 and the coefficient of linear expansion differs at a position in the plane, the direction in which the coefficient of linear expansion in the entire surface is large is changed to the direction in which the coefficient of linear expansion of the substrate is large. And

The intersection angle at which the direction L1 of the first substrate 11a having a large coefficient of linear expansion intersects with the direction L2 of the second substrate 11b having a large coefficient of linear expansion is not limited to 90 degrees. Just do it. It is preferable that the narrower one of the intersection angles is 30 to 90 degrees, since the warpage is particularly small. In particular, in the case of 45 degrees, the curvature of the four sides is corrected to approximately the same degree, and therefore, the warpage is particularly reduced.

In the above embodiment, the first substrate 11
Although the embodiment in which one prepreg 15 is interposed and stacked between the first prepreg 15 and the second substrate 11b has been described,
5 is not limited to one sheet, but may be a plurality of sheets. When a plurality of the prepregs 15 are sandwiched, the prepregs 15 may be laminated so that the directions of the warp yarns are all aligned.

At least one of the substrates 11a and 11b used in the present invention is composed of a glass cloth and a cured resin having a plurality of conductor patterns 13 filled with a cured resin 14 therebetween. The plate is, for example, a predetermined number of glass cloths, bonded with a thermosetting resin, using a plate having a metal foil stretched on one or both sides, etching the metal foil on the surface, the conductor After forming the pattern 13, a thermosetting resin is applied between the conductor patterns 13, and then the thermosetting resin is cured so that the space between the conductor patterns 13 is filled with a cured resin 14 or a metal foil. Metal plating is performed on a plate to which a glass cloth that is not stretched is adhered with a thermosetting resin to form a conductor pattern 13, a thermosetting resin is applied between the conductor patterns 13, and then the thermosetting resin is applied. The cured, the conductor patterns 13
An example in which the space is filled with the cured resin 14 is given.

When a substrate having no conductive pattern 13 on its surface is used, a substrate obtained by bonding a glass cloth with a thermosetting resin or the like may be used.

The glass cloth is not particularly limited, and a glass cloth having a thickness of 0.04 to 0.3 mm is generally used. Further, as the thermosetting resin, epoxy resin, phenol resin, polyimide resin, unsaturated polyester resin, polyphenylene ether resin and the like thermosetting resins, and these thermosetting resins inorganic fillers And the like. The thermosetting resin used for the substrates 11a and 11b and the thermosetting resin used for the cured resin 14 filling the space between the conductor patterns 13 may be the same or different.

Incidentally, inside the substrates 11a and 11b, there may be provided a hole in which a metal film is formed on the conductor pattern or the wall surface thereof, a hole having no metal film on the wall surface, or the like. It should be noted that the surfaces of the substrates 11a and 11b used in the present invention that are not in contact with the prepreg 15 may have a metal layer, and the insulating portions may be exposed.

The metal forming the conductor pattern 13 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 15 used in the present invention is formed by impregnating a glass cloth with a thermosetting resin, heating and semi-curing as necessary, and forming a sheet. The thermosetting resin used for the prepreg 15 is the same as the substrate 11a, 1
The thermosetting resin used for 1b and the thermosetting resin used for the cured resin 14 filling the space between the conductor patterns 13 may be the same or different.

After laminating the substrates 11a and 11b and the prepreg 15, the conditions for heating and pressing are as follows.
Heating and pressurizing may be appropriately performed under the conditions in which the thermosetting resin in 5 cures. However, if the pressurizing pressure is too high, the obtained laminate and printed wiring board tend to be more warped. It is preferable to apply the pressure as low as possible within a range where the substrates 11a and 11b and the prepreg 15 can be integrated.

[Method of Manufacturing Printed Wiring Board According to Claim 3 of the Present Invention] One embodiment of the method of manufacturing a printed wiring board according to claim 3 of the present invention has a metal layer on one entire surface. A first substrate having a plurality of inner layer conductor patterns filled with a resin cured material on one surface, and a second substrate having a metal layer on the entire surface on the other surface; A prepreg manufactured by impregnating a glass cloth with a resin is used.

Then, after laminating the prepreg between the first substrate and the second substrate such that the conductor pattern for the inner layer filled with the cured resin is in contact with the prepreg, the laminate is heated. A multi-layer laminate having a conductor pattern in the inner layer and a metal layer in the outer layer is manufactured by pressing and integrating.

Next, the laminated plate is perforated if necessary, and then a plating process is performed to form a through-hole plating film in the perforated hole for conducting the inner conductor pattern and the outer metal layer. A printed wiring board is manufactured by etching a layer to form a conductor pattern for an outer layer.

As shown in FIG. 3 (a), the coefficient of linear expansion of each substrate is greater than the coefficient of linear expansion α1x of the first substrate 11a. In the Y direction, in which the expansion coefficient α2x is large (α2x> α1x) and orthogonal to the X direction, the linear expansion coefficient α2y of the second substrate 11b is larger than the linear expansion coefficient α1y of the first substrate 11a. (Α2y>
α1y). Therefore, FIG.
As shown in (b), the laminate 1 obtained by heating and pressing
0 is a bowl-shaped shape in which all four sides are curved in the same direction.

The bowl shape is a shape corrected to a shape close to a planar shape as compared with a half-cylindrical shape manufactured by a conventional manufacturing method as shown in FIG. 4B. Therefore, the laminate 10 has a smaller warpage as compared with the conventional method. The printed wiring board obtained by using the laminated board 10 having a small warp also has a small warp.

A substrate, a prepreg, a conductor pattern, a cured resin for filling between conductor patterns, and a thermosetting resin used for the production of a substrate or a prepreg used in the method of manufacturing a printed wiring board according to claim 3 of the present invention. Examples of the glass cloth include those similar to those used in the method for manufacturing a printed wiring board according to claim 1 of the present invention. Further, the conditions for heating and pressing after laminating the substrate and the prepreg are preferably the same as the method for manufacturing a printed wiring board according to claim 1 of the present invention.

[0043]

According to the method for manufacturing a printed wiring board according to the first aspect of the present invention, two printed wiring boards are laminated so that the directions having large linear expansion coefficients intersect with each other, so that the printed wiring board having a small warpage is obtained. Is obtained.

According to a third aspect of the present invention, there is provided a method of manufacturing a printed wiring board, comprising: laminating one substrate so that the coefficient of linear expansion in the X direction is larger than the coefficient of linear expansion of the other substrate in the X direction; Since the one substrate is laminated so that the coefficient of linear expansion in the Y direction of the other substrate is greater than the coefficient of linear expansion of the other substrate in the Y direction, a printed wiring board with small warpage can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a method for manufacturing a printed wiring board according to claim 1 of the present invention, wherein (a) is a perspective view illustrating lamination, and (b) is a cross section illustrating lamination. Figure,
FIG. 4C is a cross-sectional view illustrating a state after heating and pressing.

FIGS. 2A and 2B are diagrams showing another embodiment of the method for manufacturing a printed wiring board according to claim 1 of the present invention, wherein FIG. 2A is a perspective view illustrating lamination, and FIG. It is a perspective view.

3A and 3B are diagrams showing one embodiment of a method for manufacturing a printed wiring board according to claim 3 of the present invention, wherein FIG. 3A is a perspective view illustrating lamination, and FIG. 3B is a perspective view illustrating warpage. FIG.

4A and 4B are diagrams illustrating a conventional method for manufacturing a printed wiring board, wherein FIG. 4A is a perspective view illustrating lamination, and FIG. 4B is a perspective view illustrating warpage.

FIGS. 5A and 5B are diagrams illustrating warpage, FIG. 5A is a diagram illustrating a printed wiring board according to claim 1 of the present invention, and FIG. 5B is a diagram illustrating a conventional printed wiring board.

FIG. 6 is a process diagram illustrating another conventional method for manufacturing a printed wiring board.

FIG. 7 shows another conventional method for manufacturing a printed wiring board.
It is sectional drawing explaining a part of process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Laminated board 11a, 11b, 31a, 31b Substrate 12, 32 Metal layer 13, 33, 38 Conductive pattern 14, 34 Resin hardened material 15, 35 Pre-preg 37 Through-hole plating film 39 Bubbles L1, L2 Direction of large linear expansion coefficient α1x, α1y, α2x, α2y Linear expansion coefficient S Warp

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

Claims (3)

[Claims] At least one of the two substrates is made of a glass cloth and a cured resin having a plurality of conductive patterns on the surface of which are filled with a cured resin, and a thermosetting resin. Using a prepreg impregnated with a glass cloth, laminating the prepreg between the substrates so that the conductor pattern filled with the cured resin is in contact with the prepreg, and then heating and pressing In the method of manufacturing a printed wiring board to be manufactured, the method of laminating the substrates is a method of laminating two substrates so that the directions having large linear expansion coefficients cross each other. Production method. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the crossing angle of each substrate at which the direction having a large linear expansion coefficient crosses is 30 to 90 degrees. 3. At least one of the two substrates is made of a glass cloth and a cured resin having a plurality of conductor patterns on the surface of which are filled with a cured resin, and a thermosetting resin. Using a prepreg impregnated with a glass cloth, laminating the prepreg between the substrates so that the conductor pattern filled with the cured resin is in contact with the prepreg, and then heating and pressing In the method of manufacturing a printed wiring board to be manufactured, the method of laminating the substrates is such that the linear expansion coefficient of one substrate in the X direction is determined by the X-direction of the other substrate.
While laminating so as to be larger than the linear expansion coefficient in the direction,
A method of laminating one of the substrates so that the coefficient of linear expansion in the direction Y perpendicular to the direction X is greater than the coefficient of linear expansion in the direction Y of the other substrate. Manufacturing method of wiring board.