JPH11274720A - Manufacture of multilayer-laminated board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of a multilayer-laminated board that can provide a highly reliable multilayer-laminated board without having void as well as set the insulation characteristics of the insulating layer, etc., as required. SOLUTION: A metal foil 4 is stacked on a circuit board 2 having circuits 1 on the surface via an insulating material 3, then heated all together under pressure to laminate the circuit board 2 and the metal foil 4 in this manufacture of a multilayer-laminated board. Thickness adjusters 5 that are generally as thick as the circuits 1 are provided in spaces where a circle of 10 mm or longer in diameter can fit between circuits 1 on the surface of the circuit board 2. Consequently, the thickness of the insulating layer formed with the insulating material 3 is made generally uniform so that characteristics such as insulating performance, etc., can be generally uniform. The insulating material 3 reaches every part between the circuits 1 or between the circuits 1 and the thickness adjusters 5.

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 multilayer laminate used for forming a multilayer printed wiring board used for electronic equipment such as a calculator and a communication device.

[0002]

2. Description of the Related Art Conventionally, in forming a multilayer laminate, a metal foil is laminated via an insulating material on the surface of a circuit board having a circuit inside or on a surface, and the insulating material is cured by heating and pressing. At the same time, the circuit board and the metal foil are integrally bonded with a cured insulating material. In the multilayer laminate thus formed, the circuit board becomes an inner layer circuit board (core material), the circuit of the circuit board becomes an inner layer circuit, and the cured insulating material becomes an insulating layer. It has a structure that has a metal foil on the outer layer.The outermost metal foil is subjected to processing such as etching to form an outer layer circuit, or through-holes, via holes, through-hole plating, and via-hole plating. Thus, a multilayer printed wiring board is formed from the multilayer laminate. As the insulating material, a prepreg (insulating sheet containing a glass substrate) is used. In this case, after the prepreg is laminated on the circuit board, a metal foil is laminated on the surface of the prepreg, and the A metal foil is laminated on the surface via an insulating material.

Recently, a method of manufacturing a multilayer laminate called a build-up method has been proposed. The build-up method is performed as shown in FIGS. First, as shown in FIG. 3A, a metal foil is superimposed on the surface of the circuit board 2 via an insulating material 3 and is heated and pressurized to cure the resin of the insulating material 3 and to cure the circuit by the cured insulating material 3. The plate 2 and the metal foil 4 are integrally bonded. At this time, the cured insulating material 3 becomes the insulating layer 8. Next, as shown in FIG. 3B, a circuit 9 is formed on the surface of the insulating layer 8 by performing a circuit forming process such as etching on the metal foil 4. Next, as shown in FIG. 3C, via holes 15 are formed at predetermined locations by laser processing or the like. Next, as shown in FIG. 3D, a plating layer 16 is formed on the inner surface of the via hole 15 and the surfaces of the circuits 1 and 9. Thus, the multilayer laminate is manufactured by the build-up method. If it is desired to further increase the number of layers after FIG. 3D, the steps of FIGS. 3A to 3D are repeated.

As shown in FIG. 3A, as a method of laminating a metal foil on the surface of a circuit board 2 with an insulating material 3 interposed therebetween, a resin film (base such as prepreg) cured to a B-stage state is used. There is a method of arranging a film without a material on the surface of the circuit board 2 and arranging the metal foil 4 on the surface of the resin film. Another method is to apply a resin varnish to one side of the metal foil 4, dry the resin varnish, and cure the resin to a B-stage state, thereby forming a metal foil with an insulating material 3 on the metal foil. 4 is formed, and this resin-attached metal foil is disposed so as to overlap the surface of the circuit board 2.

However, in the method of manufacturing a multilayer laminate by the above-described build-up method, there are portions where the circuit 1 exists on the surface of the circuit board 2 and portions where the circuit 1 does not exist. Therefore, when the metal foil 4 is integrated with the circuit board 2, a large amount of the insulating material 3 flows in a portion (concave portion) where the circuit 1 does not exist when the metal foil 4 is integrated with the circuit board 2. In this portion, the thickness of the insulating layer 8 is increased, and the portion where the circuit 1 is present (convex portion)
The thickness of the insulating layer 8 becomes small, the thickness of the insulating layer 8 becomes uneven, and the characteristics such as the insulating performance become uneven, so that a reliable multilayer laminate cannot be formed. there were. If the flow of the insulating material 3 is insufficient, there is a possibility that blurring or voids may occur in a portion where the circuit 1 does not exist.

Therefore, as shown in FIG. 4, a multilayer laminate is manufactured using two types of insulating materials 3a and 3b. In this method, the insulating material 3b in the C-stage is superimposed on one surface of the metal foil 4, and then the insulating material 3b in the B-stage is placed on the surface of the insulating material 3b in the C-stage.
a is superposed to form a metal foil with resin, and then the insulating material 3a in the B-stage state is brought into contact with the surface of the circuit board 2 to superimpose the metal foil with resin on the circuit board 2, and then superposed. The product is heated and pressed. In the multilayer laminate formed by this method, an insulating layer 8 is formed of a cured product of the insulating material 3a in the B-stage state and a cured product of the insulating material 3b in the C-stage state. Also, the insulating material 3a in the B-stage state is partially embedded between the circuits 1 by the above-mentioned heat and pressure molding to change its thickness, but the insulating material 3b in the C-stage state is formed even after the above-mentioned heat and pressure molding. The thickness is almost unchanged. Therefore, this multilayer laminate is made of a cured product of the insulating material 3b in the C-stage state, and
Is formed so as to secure the embedding (adhesion) of the insulating layer 8 into the circuit 1 of the circuit board 2 with the cured material of the insulating material 3a in the B-stage state. By securing the thickness of the insulating layer 8 with the cured product of the material 3b, the non-uniformity of the thickness of the insulating layer 8 is reduced as compared with those shown in FIGS.

However, even when a multilayer laminate is manufactured using two kinds of insulating materials as described above, a large non-circuit-forming portion (a circuit is formed between the circuits 1 of the circuit board 2). The non-existing portion 10 makes it difficult for the insulating material 3a in the B-stage state to spread to every corner of the non-circuit-forming portion 10, and as a result, voids are generated in the non-circuit-forming portion 10 and the reliability of the multilayer laminate is increased. There was a problem that it became low. In addition, if it is attempted to optimize the adhesiveness, handleability, and moldability of the insulating material 3a in the B and C stage states, B, C
The type of resin for forming the insulating materials 3a and 3b in the C-stage state is considerably limited, and there is a problem that it is difficult to freely set the insulating characteristics and the like of the insulating layer 8.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention is to provide a multilayer laminate having high reliability without voids and capable of freely setting the insulation characteristics of the insulating layer. It is an object of the present invention to provide a method for manufacturing a plate.

[0009]

According to the first aspect of the present invention, an insulating material is provided on a circuit board having a circuit on its surface.
A method for producing a multilayer laminate in which a metal foil 4 is overlapped via a substrate and heated and pressurized to laminate the circuit board 2 and the metal foil 4 integrally, wherein the circuit 1 on the surface of the circuit board 2 and the circuit 1 A thickness auxiliary portion 5 having a thickness substantially equal to that of the circuit 1 is provided in a portion having a size such that a circle having a diameter of 10 mm or more can be inserted therebetween.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the size of the circuit board 2 is such that a circle having a diameter of 10 mm or more between the circuits 1 on the surface of the circuit board 2 is inserted. A non-conducting circuit 7 not connected to the circuit 1 is formed in
The non-conducting circuit 7 is formed as a thickness auxiliary portion 5. According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the size of the circuit board 2 is such that a circle having a diameter of 10 mm or more between the circuits 1 on the surface of the circuit board 2 is inserted. The thickness assisting portion 5 is formed by applying a resin material to the portion and curing the resin material.

According to a fourth aspect of the present invention, in addition to the constitution of the third aspect, a resin material containing a filler is used.

[0012]

Embodiments of the present invention will be described below. For example, the circuit board 2 used in the present invention forms a circuit 1 on the surface by performing a circuit forming process such as etching on a metal foil (copper foil or the like) on the surface of the double-sided copper-clad laminate, and forms the circuit 1 on the surface. The thickness assisting portion 5 is provided in the circuit non-forming portion 10 between the circuits 1 (a portion surrounded by the plurality of circuits 1).
Are formed. The thickness auxiliary part 5 is the circuit 1
As shown in FIG. 2, the thickness assisting portion 5 is formed in a portion of the circuit non-forming portion 10 having a size that can accommodate a circle having a diameter of 10 mm or more. In particular, it is preferable to form the thickness assisting portion 5 in a portion that is removed by a process such as punching after forming the multilayer laminate, whereby the thickness assisting portion 5 is removed at the same time as the multilayer laminate is processed. And workability is improved. In addition, it is preferable that the thickness assisting portion 5 is formed in such a size that the dimension between the end of the circuit 1 and the end of the thickness assisting portion 5 is 10 mm or less, more preferably 5 mm or less.
It is preferable that the dimension between the end of the circuit 1 and the end of the thickness assisting portion 5 is as small as possible.

The difference between the circuits 1 depends on the type of the circuit board 2 and the like. The upper limit of the diameter of the circle is not particularly set.
Since the thickness is about m, the thickness assisting portion 5 is formed in the portion of the circuit non-forming portion 10 having a size that can accommodate a circle having a diameter of 10 to 200 mm. Of course, the thickness assisting portion 5 may be formed in a portion of the circuit non-forming portion 10 having a size that can accommodate a circle having a diameter of 200 mm or more.

In forming the thickness assisting portion 5, two methods can be adopted. One of them is to form a non-conductive circuit portion 7 that is not electrically connected to the circuit 1 from a part of the metal foil in a circuit forming step of the circuit board 2, and to form the non-conductive circuit portion 7 of the solid metal foil with a thickness. The auxiliary part 5 is formed. Generally, the formation of the circuit 1 on the circuit board 2 is performed as follows. First, dry film (etching resist film) on metal foil on the surface of double-sided copper-clad laminate
And a mask having a desired circuit pattern on the surface of the dry film. Next, the portion of the dry film not covered with the mask is cured by exposure. Next, after removing the mask, the uncured portion covered with the mask of the dry film is removed by development to expose the metal foil. Thereafter, an etching solution is supplied to an exposed portion of the metal foil to perform an etching process, and an unnecessary portion of the metal foil is removed. In this way, the portion of the metal foil covered with the dry film and not subjected to the etching process remains on the surface of the circuit board 2 as the circuit 1.

In the present invention, a non-conductive circuit portion pattern is added to the circuit pattern of the mask so that a portion of the metal foil to be formed as the non-conductive circuit portion 7 remains,
The circuit 1 and the non-conductive circuit portion 7 are formed using this mask. Since the circuit 1 and the non-conductive circuit portion 7 are formed at the same time, a process for forming the thickness auxiliary portion 5 is not required, and even if the thickness auxiliary portion 5 is formed, an increase in cost can be suppressed. Things.

As another method of forming the thickness assisting portion 5, a circuit forming process is performed on the double-sided copper-clad laminate in the same manner as described above to form the circuit board 2, and then the resin on the portion of the circuit non-forming portion 10 is formed. The material is applied and dried and cured. As the resin material, those used as an etching resist material, a solder resist material, a sealant, a resin for filling holes, and the like can be used. As a method of applying the resin material, it is simple and preferable to employ printing such as silk screen printing. Further, it is preferable that the resin material contains a filler, so that the coefficient of thermal expansion of the thickness auxiliary portion 5 can be reduced, and the thickness of the portion of the multilayer laminated board where the circuit 1 or the thickness auxiliary portion 5 does not exist is different from the thickness. The difference in thermal expansion (thermal deformation) during heating from the portion where the auxiliary portion 5 is formed can be reduced. Alumina, titanium oxide, silicon dioxide (Si
O ₂ ), BN (boron nitride), aluminum hydroxide and the like can be used. In the case where the auxiliary thickness portion 5 is formed in a portion to be removed by punching or the like as described above, it is also possible to use a conductive material such as copper powder, iron powder, or carbon powder.

The formation of a multilayer laminate using the circuit board 2 as described above is performed as follows. First, as shown in FIG. 1A, a metal foil 4 such as a copper foil is overlapped on the surface of a circuit board 2 with an insulating material 3 interposed therebetween, and this is heated and pressed to harden and cure the resin of the insulating material 3. The circuit board 2 and the metal foil 4 are integrally bonded with the insulating material 3. At this time, the cured insulating material 3 becomes the insulating layer 8. As a method of laminating the metal foil 4 on the surface of the circuit board 2 with the insulating material 3 interposed therebetween, a resin film (based on a prepreg such as a prepreg) formed using a resin such as an epoxy resin and cured to a B-stage state is used. There is a method of arranging a film without material) on the surface of the circuit board and arranging the metal foil 4 on the surface of the resin film.

As another method, a resin varnish containing a resin such as an epoxy resin is applied to one surface of the metal foil 4, and the resin varnish is dried and the resin is cured to a B-stage state. There is a method in which a resin-coated metal foil provided with an insulating material is formed, and the resin-coated metal foil is disposed so as to overlap the surface of the circuit board. FIG. 1
As shown in FIG. 2B, a circuit 9 is formed on the surface of the insulating layer 8 by performing a circuit forming process such as etching on the metal foil 4. Next, as shown in FIG. 1C, via holes 15 are formed at predetermined locations by laser processing or the like. Next, as shown in FIG. 1D, a plating layer 16 is formed on the inner surface of the via hole 15 and the surfaces of the circuits 1 and 9. Thus, the multilayer laminate is manufactured by the build-up method. If it is desired to further increase the number of layers after FIG.
To (d) are repeated.

In the present invention, the thickness assisting portion 5 having a thickness substantially equal to that of the circuit 1 is provided on the surface of the circuit board 2 on the surface of the circuit board 2 where the circuit 1 has a circle having a diameter of 10 mm or more. The thickness auxiliary portion 5 prevents the insulating material 3 from flowing much in a portion where the circuit 1 does not exist during the heating and pressing when the metal foil 4 is integrated with the circuit board 2. For this reason, the thickness of the insulating layer 8 formed from the insulating material 3 can be made substantially uniform, so that characteristics such as insulation performance can be made substantially uniform, and a highly reliable multilayer laminate can be formed. Can be done. Further, by providing the thickness assisting portion 5, the circuit 1 of the circuit board 2 and the circuit 1
A large space (gap) does not exist between them, and the insulating material 3 spreads to every corner between the circuit 1 and the circuit 1 or between the circuit 1 and the thickness auxiliary portion 5, so that the void It is possible to prevent the occurrence of such a problem and to form a highly reliable multilayer laminate. Further, any material can be used as the insulating material 3. By appropriately selecting and using various materials as the insulating material 3, the insulating characteristics of the insulating layer 8 can be freely designed and set. It is.

[0020]

The present invention will be described below in detail with reference to examples. (Embodiment 1) A circuit board 2 having a copper foil circuit 1 having a thickness of 20 μm, in which the size of a circuit non-formed portion 10 between the circuits 1 is 50 × 50 mm Was used. A resist ink (PSR-4000 manufactured by Taiyo Ink Manufacturing Co., Ltd.) is printed and applied to the circuit non-formed portion 10 of the circuit board 2 to a size of 45 × 45 mm, and dried to obtain a circuit 1 and a circuit. The thickness auxiliary part 5 having substantially the same thickness was formed. Next, a resin-attached copper foil is superimposed on the circuit board 2 and is heated at 170 ° C. for 1 to 1.5 hours at 30 kg /
Heat and pressure were applied at a pressure of cm ² , and a multilayer laminate for testing was formed by vacuum forming. As the resin-attached copper foil, a resin (insulating material 3) having a thickness of 60 μm and a copper foil (metal foil 4) having a thickness of 18 μm was used. As the resin, an epoxy resin was used.

(Embodiment 2) The circuit board 2 has a thickness of 2
It has a circuit 1 of a copper foil of 0 μm.
The size of the circuit non-formation portion 10 between 50 mm and 50 mm was used. Circuit non-forming portion 1 of this circuit board 2
0 is provided with a copper foil thickness auxiliary portion 5 (non-conductive circuit portion 7) formed simultaneously with the formation of the circuit 1, and this thickness auxiliary portion 5 is formed in a size of 40 × 40 mm. .
Using such a circuit board 2, a multilayer laminate was formed in the same manner as in Example 1 above.

(Embodiment 3) The circuit board 2 has a thickness of 3
It has a circuit 1 of copper foil of 5 μm, and the circuit 1 and the circuit 1
The size of the circuit non-formation portion 10 between 50 mm and 50 mm was used. Circuit non-forming portion 1 of this circuit board 2
0 for embedding resin (PHP-90 manufactured by Yamaei Chemical Co., Ltd.)
0, containing epoxy resin and inorganic filler)
The thickness auxiliary portion 5 having substantially the same thickness as the circuit 1 was formed by printing and applying a size of 5 × 45 mm, followed by drying. Using such a circuit board 2, a multilayer laminate was formed in the same manner as in Example 1 above.

(Comparative Example) The circuit board 2 has a thickness of 35.
A circuit having a circuit 1 of a copper foil of μm and having a size of the circuit non-formed portion 10 between the circuits 1 of 40 × 40 mm was used. Using such a circuit board 2, a multilayer laminate was formed in the same manner as in Example 1 above.

With respect to the examples 1 to 3 and the comparative examples manufactured as described above, the thickness was measured at a plurality of places using a micrometer, and the average value, the maximum value, and the minimum value were obtained. In Examples 1 to 3 and Comparative Example, the occurrence of voids was observed. In addition, it was recognized that voids were generated in those in which fading, whitening and swelling had occurred in appearance. Table 1 shows the results.

[0025]

[Table 1]

As can be seen from Table 1, in Examples 1 to 3, there was little variation in thickness and there was no void, but in the comparative example, there was a large difference between the maximum value and the minimum value of the thickness. Voids also occurred.

[0027]

As described above, according to the first aspect of the present invention, a metal foil is superimposed on a circuit board having a circuit on the surface via an insulating material, and this is heated and pressed to form a circuit board and a metal. A method for manufacturing a multilayer laminate in which foils are integrally laminated, wherein a portion of a surface of a circuit board having a size such that a circle having a diameter of 10 mm or more between circuits is included, having a thickness substantially equal to that of the circuit. Since the thickness auxiliary portion is provided, it is possible to prevent a large amount of insulating material from flowing to a portion where a circuit does not exist due to the presence of the thickness auxiliary portion during heating and pressing when integrating the metal foil on the circuit board. In addition, the thickness of the insulating layer formed of an insulating material is substantially uniform, and characteristics such as insulating performance can be substantially uniform, so that a highly reliable multilayer laminate can be formed. In addition, by providing the thickness auxiliary portion, it is possible to prevent a large space from being present between the circuits on the circuit board, and the insulating material is provided between the circuit and the circuit or between the circuit and the thickness auxiliary portion. It is possible to prevent the occurrence of voids by spreading, and to form a highly reliable multilayer laminate. Further, an arbitrary insulating material can be used, and the insulating characteristics and the like can be freely set by appropriately selecting and using various insulating materials. Therefore, the multilayer laminate formed by this method can be suitably used for producing a multilayer printed wiring board having high performance which requires stability of characteristic impedance.

According to a second aspect of the present invention, a non-conductive portion that is not electrically connected to a circuit is provided on a portion of a surface of a circuit board having a size such that a circle having a diameter of 10 mm or more is inserted between the circuits. Since the circuit portion is formed and the non-conductive circuit portion is formed as a thickness auxiliary portion, the circuit and the non-conductive circuit portion can be formed at the same time. Even if the portion is formed, an increase in cost can be suppressed.

According to a third aspect of the present invention, a resin material is applied to a portion of a surface of a circuit board having a size such that a circle having a diameter of 10 mm or more between the circuits is formed and cured. Since the thickness assisting portion is formed by using the thickness assisting portion, the thickness assisting portion can be easily formed. Claim 4 of the present invention
The invention described in (1) uses a resin material containing a filler, so that the coefficient of thermal expansion of the thickness auxiliary portion can be reduced, and the portion where the circuit or the thickness auxiliary portion does not exist and the portion where the thickness auxiliary portion is formed And a difference in thermal expansion upon heating can be reduced, and a multilayer laminate having high heat resistance can be formed.

[Brief description of the drawings]

FIG. 1 illustrates an example of an embodiment of the present invention, and (a) to (d) are cross-sectional views.

FIG. 2 is a plan view showing the circuit board according to the first embodiment.

FIG. 3 shows a conventional example, and (a) to (d) are cross-sectional views.

FIG. 4 is a sectional view showing another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit 2 Circuit board 3 Insulating material 4 Metal foil 5 Thickness auxiliary part

Claims (4)

[Claims] 1. A method for producing a multilayer laminate, comprising: laminating a metal foil on a circuit board having a circuit on the surface via an insulating material, heating and pressing the metal foil, and laminating the circuit board and the metal foil integrally. A multilayer laminated board characterized in that a thickness auxiliary portion having a thickness substantially equal to that of a circuit is provided in a portion of a surface of the circuit board having a size such that a circle having a diameter of 10 mm or more between the circuits is inserted. Production method. 2. A circuit having a diameter of 1 between circuits on the surface of the circuit board.
2. A non-conductive circuit portion which is not electrically connected to a circuit is formed in a portion having a size such that a circle of 0 mm or more is inserted therein, and the non-conductive circuit portion is formed as a thickness auxiliary portion.
3. The method for producing a multilayer laminate according to item 1. 3. A circuit having a diameter of 1 between circuits on the surface of the circuit board.
The method for producing a multilayer laminate according to claim 1 or 2, wherein a resin material is applied to a portion having a size such that a circle of 0 mm or more is formed and cured to form a thickness auxiliary portion. 4. The method for producing a multilayer laminate according to claim 3, wherein a resin material containing a filler is used.