JPH09260842A - Multilayerd printed wiring board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered printed wiring board manufacturing method enabling the high-strength adhesion of a metal layer to a thermosetting resin layer. SOLUTION: On the surface of an inner layer circuit board with a wiring pattern 1 formed thereon a thermosetting resin layer 4 having a rough surface 3 is formed and the surface of this layer 4 is plated with a metal to form a metal layer 5 for forming a conductor circuit 6, thereby manufacturing a multilayer printed wiring board wherein the resin layer 4 is formed with a semicured resin and its curing deg. is raised after the metal plating on the surface of this layer 4. This increases the adhesion strength of the metal layer 5 to the resin layer 4, compared with that is the case of plating the metal layer 5 on the completely cured thermosetting resin layer 4.

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 printed wiring board suitable for high density mounting.

[0002]

2. Description of the Related Art As one of methods for manufacturing a multilayer printed wiring board, a thermosetting resin layer is provided by applying a thermosetting resin to the surface of an inner layer circuit board on which a wiring pattern is formed and curing the resin. There is a method in which the surface of the thermosetting resin layer is plated with metal to form a metal layer, and the conductor layer is formed by etching the metal layer.

As described above, since the conductor circuit is often formed by the metal layer plated on the surface of the thermosetting resin layer, it is required that the adhesion strength of the metal layer to the thermosetting resin layer is high. To be done. Therefore, conventionally, the surface of the thermosetting resin layer that has been sufficiently cured is formed into a rough surface, and metal plating is applied to the surface of the thermosetting resin layer that has become the rough surface. The metal layer is adhered to the thermosetting resin layer with high strength.

[0004]

However, in terms of adhering the conductor circuit, which is thinned due to high-density mounting, to the thermosetting resin layer with high strength, the adhesion strength of the metal layer to the thermosetting resin layer is high. Was still not enough. The present invention has been made in view of the above points, and an object of the present invention is to provide a method for manufacturing a multilayer printed wiring board capable of closely adhering a metal layer to a thermosetting resin layer with high strength. .

[0005]

A method for manufacturing a multilayer printed wiring board according to the present invention is a thermosetting method in which a roughened surface 3 is formed on the surface of an inner layer circuit board 2 on which a wiring pattern 1 has been formed. When a multilayer printed wiring board is manufactured by a step of providing a resin layer 4 and plating the surface of the thermosetting resin layer 4 with a metal to form a metal layer 5 for forming a conductor circuit 6, a thermosetting resin is used. The layer 4 is formed of a semi-cured resin, and after the surface of the thermosetting resin layer 4 is plated with metal, the degree of curing of the resin of the thermosetting resin layer 4 is increased. .

Further, in the invention of claim 2, the glass transition temperature of the resin of the thermosetting resin layer 4 in the semi-cured state is a temperature lower by 20 ° C. or more than the maximum glass transition temperature reached after increasing the curing degree. It is characterized by that. Further, the invention of claim 3 is characterized in that the thermosetting resin layer 4 is dried at room temperature before metal plating is applied to the thermosetting resin layer 4.

Further, the invention of claim 4 is the thermosetting resin layer 4
Before the metal plating is applied to the thermosetting resin layer 4, the thermosetting resin layer 4 is dried by heating at a temperature lower than the glass transition temperature of the resin of the thermosetting resin layer 4. The invention of claim 5 is characterized in that the thermosetting resin layer 4 is dried under reduced pressure before the metal plating is applied to the thermosetting resin layer 4.

Further, the invention of claim 6 is the thermosetting resin layer 4
It is characterized in that the thermosetting resin layer 4 is dried by centrifugal dehydration before the metal plating is applied to. Further, the invention of claim 7 is characterized in that when the metal plating is performed by electroless plating and electrolytic plating subsequent to electroless plating, the thermosetting resin layer 4 is dried after the electroless plating. .

[0009]

Embodiments of the present invention will be described below. The inner layer circuit board 2 is not particularly limited, and any one can be used. For example, the one in which the wiring pattern 1 is formed by a copper foil or the like on the surface of the glass cloth base material epoxy resin laminated plate is exemplified. can do. It is preferable that the surface of the wiring pattern 1 is subjected to an oxidation treatment generally called blackening treatment so that the surface of the wiring pattern 1 is roughened.

The surface of the inner-layer circuit board 2 is shown in FIG.
The thermosetting resin layer 4 is provided as in (b). The resin of the thermosetting resin layer 4 is not particularly limited, but an epoxy resin, a polyimide resin, or the like can be used. The method for providing the thermosetting resin layer 4 on the surface of the inner layer circuit board 2 is not particularly limited, but there are various methods as follows.

First, using a resin-coated metal foil in which a thermosetting resin is applied to the surface of a metal foil such as a copper foil, the resin-coated metal foil is placed on the inner layer circuit board 2 on the resin side and heated and pressed. There is a method in which the thermosetting resin layer 4 is provided on the surface of the inner layer circuit board 2 by etching and removing the metal foil after the resin is laminated and adhered to the surface of the inner layer circuit board 2. In this case, the heating temperature at the time of stacking is preferably 150 ° C., and the heating time is preferably about 60 to 120 minutes.

Further, by laminating a thermosetting resin film on the surface of the inner layer circuit board 2 and applying heat and pressure to laminate the thermosetting resin film on the surface of the inner layer circuit board 2, the inner layer circuit board 2 is adhered. There is a method of providing the thermosetting resin layer 4 on the surface of 2. In this case, the heating temperature during stacking is 15
The heating time at 0 ° C. is preferably about 60 to 120 minutes. Furthermore, there is a method in which a composition obtained by dissolving a thermosetting resin in a solvent is coated on the surface of the inner layer circuit board 2 and dried to form the thermosetting resin layer 4 on the surface of the inner layer circuit board 2.
In this case, heat treatment is performed at 110 ° C. for about 30 minutes to remove the solvent, and 6 ° C. at 150 ° C. to accelerate the resin curing.
It is preferable to perform heat treatment for about 0 to 120 minutes.

Although the thermosetting resin layer 4 can be provided on the surface of the inner layer circuit board 2 as described above, the thermosetting resin layer 4 is formed of a semi-cured thermosetting resin in the present invention. It is a thing. Here, the semi-cured state is a so-called B-stage state, and is a state in which the material can be sufficiently cured (including gelation) through heating in a fluidized state. The standard of the semi-cured state of the thermosetting resin layer 4 is that the glass transition temperature of the resin is 2 compared to the maximum glass transition temperature reached when the resin of the thermosetting resin layer 4 is sufficiently cured.
It is preferable that the temperature is lower than 0 ° C. Although the lower limit of the semi-cured state of the thermosetting resin layer 4 is not particularly set,
It is preferable to set the lower limit to a state where the glass transition temperature of the resin of the thermosetting resin layer 4 is about 80 ° C. lower than the highest glass transition temperature. As described above, in the present invention, in order to stack the thermosetting resin layer 4 on the circuit board 2 for inner layer, the resin of the thermosetting resin layer 4 is bonded to the circuit board 2 for inner layer by advancing the curing reaction to some extent. The degree of cure of the resin of the thermosetting resin layer 4 is controlled to a low level of the glass transition temperature which is lower than the maximum glass transition temperature by 20 ° C. or more.

In the present invention, the glass transition temperature is DSC under the conditions of a heating rate of 10 ° C./min and a sample amount of 10 mg.
(Differential Scanning Ca
lorimeter; differential scanning calorimeter) method.
Further, the maximum glass transition temperature reached when the resin is sufficiently cured means the glass transition temperature by varying the curing conditions (heating temperature, heating time) of the thermosetting resin used for the thermosetting resin layer 4. It is the highest glass transition temperature obtained at the time of measurement, and an error of about ± 5 ° C. is expected, but it is a temperature unique to each thermosetting resin. When the resin of the thermosetting resin layer 4 is an epoxy resin, this maximum glass transition temperature is reached by heating at a temperature of 170 ° C. or more for 60 minutes or more to proceed with curing.

A rough surface 3 having an arbitrary roughness is formed on the surface of the thermosetting resin layer 4 in the semi-cured state provided on the surface of the inner layer circuit board 2 as shown in FIG. 1 (c). To do. The rough surface 3 can be formed on the surface of the thermosetting resin layer 4 by chemical etching or the like. As the chemical etching, for example, a swelling agent such as a diethylene glycol-based aqueous solution is used, and the inner layer circuit board 2 provided with the thermosetting resin layer 4 is immersed in the swelling agent while heating the swelling agent. A two-step treatment method is known in which the layer 4 is swollen and then the surface of the thermosetting resin layer 4 is subjected to oxidative decomposition using an oxidative decomposer such as a potassium permanganate solution. By performing chemical etching or the like in this manner, the roughened surface 3 can be formed after the thermosetting resin layer 4 is provided on the inner layer circuit board 2. Further, when the thermosetting resin layer 4 is provided on the surface of the circuit board 2 for inner layer using the resin-coated metal foil, the rough surface of the matte surface of the metal foil is transferred to the surface of the thermosetting resin layer 4. At times, since the surface of the thermosetting resin layer 4 is a rough surface,
There is no need to perform the roughening process again.

Next, when the surface of the thermosetting resin layer 4 is roughened by chemical etching, the thermosetting resin layer 4 absorbs water in the chemical etching aqueous solution. Therefore, if the metal layer 5 is directly plated with metal to provide the metal layer 5 on the surface of the thermosetting resin layer 4 as described below, and the thermosetting resin layer 4 is heated to accelerate the curing of the thermosetting resin layer 4, the thermosetting resin layer 4 is thermally cured. There is a possibility that the heat resistance may be deteriorated, for example, the moisture absorbed in the thermosetting resin layer 4 may be evaporated and the metal layer 5 on the surface of the thermosetting resin layer 4 may be swollen and defective. For this reason, when the surface of the thermosetting resin layer 4 is roughened by using a treatment aqueous solution such as chemical etching, before the thermosetting resin layer 4 is plated with metal, the thermosetting resin layer 4 is subjected to metal plating. In order to improve heat resistance, it is preferable to dry and dry the water absorbed in the thermosetting resin layer 4 in advance. The drying is preferably performed so that the content of water in the thermosetting resin layer 4 is 1% by weight or less.

The method of drying the thermosetting resin layer 4 is not particularly limited, but for example, the following method is available. The inner-layer circuit board 2 provided with the thermosetting resin layer 4 may be left indoors at room temperature for a long time (for example, left in an atmosphere having a temperature of 25 ° C. and a relative humidity of 80% for 48 hours), or in a drying room having a low humidity at room temperature. A method in which it is left standing (for example, left in an atmosphere having a temperature of 25 ° C. and a relative humidity of 30% for 10 hours) and dried at room temperature.

A method of drying the thermosetting resin layer 4 by heating it at a temperature lower than the glass transition temperature of the resin so that the degree of curing of the resin of the thermosetting resin layer 4 does not proceed so much.
For example, when the thermosetting resin layer 4 is an epoxy resin, 60
The thermosetting resin layer 4 can be dried by heating the inner-layer circuit board 2 provided with the thermosetting resin layer 4 at a temperature of about C for about 3 hours.

A method of drying the thermosetting resin layer 4 by placing the inner layer circuit board 2 provided with the thermosetting resin layer 4 in a decompression chamber or the like to reduce the pressure. For example, 50
The thermosetting resin layer 4 can be dried by putting it in a chamber under a reduced pressure condition of -100 torr for 5 hours. A method of drying the thermosetting resin layer 4 by centrifuging and dehydrating the inner layer circuit board 2 provided with the thermosetting resin layer 4 with a centrifugal dehydrator. For example, the thermosetting resin layer 4 can be dried by performing centrifugal dehydration at a rotation speed of 500 rpm for 3 hours.

Of course, the thermosetting resin layer 4 may be dried by combining some of these methods. In addition, the inner layer circuit board 2 is formed by using a metal foil with resin.
When it is not necessary to roughen the thermosetting resin layer 4 using a treatment aqueous solution such as chemical etching as in the case where the thermosetting resin layer 4 is provided on the surface of Since it is not absorbed, it is not necessary to carry out a drying treatment.

After the thermosetting resin layer 4 is dried as necessary as described above, metal plating is performed to form a metal layer 5 on the surface of the thermosetting resin layer 4 as shown in FIG. 1 (d). . The metal plating can be performed in two steps: electroless plating such as electroless copper plating and electrolytic plating such as electrolytic copper plating. That is, first, a thin electroless film having a thickness of about 0.5 μm is provided on the surface of the thermosetting resin layer 4 by electroless plating, and then electroplating is performed by energizing the electroless film to form an electrolytic film. The metal layer 5 having a thickness of about 20 μm can be formed.

Here, when the inner-layer circuit board 2 provided with the thermosetting resin layer 4 is immersed in the electroless plating bath during electroless plating, the thermosetting resin layer 4 absorbs moisture.
Therefore, it is preferable to dry the thermosetting resin layer 4 after performing electroless plating in order to improve heat resistance as in the above. The drying can be carried out by the above-mentioned method (1) or a combination of these methods. When the thermosetting resin layer 4 is an epoxy resin, for example, it is at a temperature of 60 to 100 ° C. lower than the glass transition temperature for 30 minutes to 1 minute. The thermosetting resin layer 4 can be dried by heating for a time.

After the metal layer 5 is provided on the surface of the thermosetting resin 4 as described above, it is heated to sufficiently cure the resin of the thermosetting resin layer 4 to enhance the degree of curing. It is preferable to increase the degree of curing so that the glass transition temperature of the resin of the thermosetting resin layer 4 reaches the maximum glass transition temperature. Therefore, when the thermosetting resin layer 4 is an epoxy resin, 17
It is preferable to heat at a temperature of 0 ° C. or more for 60 minutes or more to promote curing.

As described above, according to the present invention, after the metal layer 5 is provided on the surface of the semi-cured thermosetting resin layer 4 by plating,
Since the thermosetting resin layer 4 is sufficiently cured, compared with the conventional case where the metal layer 5 is plated on the thermosetting resin layer 4 which is sufficiently cured. The adhesive strength of the metal layer 5 to the thermosetting resin layer 4 can be increased. In order to increase the adhesion strength of the metal layer 5 to the thermosetting resin layer 4 as described above, the thermosetting resin layer 4 at the time of plating the metal layer 5
As described above, the degree of the semi-cured state of the resin is preferably 20 ° C. or more lower than the maximum glass transition temperature that the glass transition temperature of the resin reaches after increasing the degree of curing, If the curing proceeds further than this, there is a possibility that the improvement in the adhesion strength of the metal layer 5 to the thermosetting resin layer 4 will be insufficient.

After the metal layer 5 is provided on the surface of the thermosetting resin layer 4 as described above and the thermosetting resin layer 4 is further cured, printed wiring processing such as exposure, development and etching is performed on the metal layer 5. By doing so, it is possible to form the conductor circuit 6 of the outer layer as shown in FIG. 1 (e) and finish it as a multilayer printed wiring board. Although FIG. 1 shows an example in which the thermosetting resin layer 4 and the metal layer 5 are provided only on one side of the inner layer circuit board 2, the thermosetting resin is provided on both sides of the inner layer circuit board 2. It goes without saying that the metal layer 5 may be provided together with the layer 4.

[0026]

EXAMPLES Next, the present invention will be specifically described with reference to examples. (Example 1) FR-4 type double-sided copper foil-clad epoxy resin laminate (laminate thickness 1.0 mm, copper foil thickness 18 μ)
m), the copper foil on one surface is etched to provide the wiring pattern 1, and the copper foil on the other surface is removed by etching over the entire surface.
And the surface of the wiring pattern 1 was blackened (see FIG. 1).
(A)).

Next, a bisphenol A type epoxy resin (hardening agent dicyandiamide) is applied to the matte surface of the copper foil to form a resin-coated copper foil (resin thickness 80 μm, copper foil thickness 18 μm).
m), the resin-coated copper foil is overlaid on the surface of the inner layer circuit board 2 on which the wiring pattern 1 is provided on the resin side.
After being heated and pressed under the conditions of 0 ° C., 40 kg / cm ² , and 60 minutes, the copper foil is etched and peeled off to form a semi-cured thermosetting resin layer having a thickness of 70 μm on the surface of the inner layer circuit board 2. 4 was formed. A part of the thermosetting resin layer 4 is sampled, and a DSC device “910DSC” manufactured by DuPont.
The glass transition temperature was 70 ° C. when the glass transition temperature was measured under conditions of a heating rate of 10 ° C./min and a sample amount of 10 mg. The surface of the thermosetting resin layer 4 was the rough surface 3 to which the rough surface of the matte surface of the copper foil was transferred (see FIG. 1 (c)).

Next, the electroless copper plating solution "Chipposit 253" manufactured by Shipley Far East Co., Ltd.
By soaking for 0 minutes and performing electroless copper plating,
An electroless copper film having a thickness of 0.5 μm was provided on the surface of the thermosetting resin layer 4. And when the electroless copper plating is completed,
After the thermosetting resin layer 4 is dried by heating at a temperature of 60 ° C. for 1 hour, 2 A / d is further applied to the electroless copper film.
Electrolytic copper plating was performed by immersing in an electrolytic copper plating bath for 50 minutes while energizing under the condition of m ² to provide a metal layer 5 having a total thickness of 20 μm on the surface of the thermosetting resin layer 4 (see FIG. 1 (d )reference).

After providing the metal layer 5 in this manner, 17
By heat treatment at 5 ° C. for 90 minutes, the thermosetting resin layer 4 was sufficiently cured to obtain a multilayer board for a multilayer printed wiring board. A part of the thermosetting resin layer 4 after curing was sampled and the glass transition temperature was measured to be 140 ° C., which was the maximum glass transition temperature. (Example 2) The heating and pressurizing conditions when the resin-coated copper foil is placed on the inner-layer circuit board 2 to form the semi-cured thermosetting resin layer 4 are set to 150 ° C, 40 kg / cm ² , and 90 minutes. A multilayer board was obtained in the same manner as in Example 1 except that the above procedure was performed.
In Example 2, the glass transition temperature of the semi-cured thermosetting resin layer 4 before the electroless copper plating was 90 ° C.

(Embodiment 3) When the resin-coated copper foil is placed on the inner layer circuit board 2 to form the semi-cured thermosetting resin layer 4, the heating and pressurizing conditions are 150 ° C., 40 kg / cm ² , 12
A multilayer board was obtained in the same manner as in Example 1 except that it was set to 0 minutes. In Example 3, the glass transition temperature of the semi-cured thermosetting resin layer 4 was 110 ° C.

Example 4 A multilayer board was obtained in the same manner as in Example 3 except that the drying was not carried out at the time when the electroless copper plating was completed. (Comparative Example 1) The same inner layer circuit board 2 as in Example 1 is used, and the same resin-coated copper foil as in Example 1 is used, and the resin-coated copper foil is provided with the wiring pattern 1 of the inner layer circuit board 2 on the resin side. Layered on the exposed surface, 170 ℃, 40kg / cm ² , 9
After heating and pressing under the condition of 0 minutes, the copper foil was etched and peeled off to form the thermosetting resin layer 4 having a thickness of 70 μm on the surface of the inner layer circuit board 2. The glass transition temperature of the thermosetting resin layer 4 was measured to be 140 ° C., and the thermosetting resin layer 4 was almost completely cured until the maximum glass transition temperature was reached. After that, electroless copper plating is performed on the surface of the thermosetting resin layer 4 in the same manner as in Example 1, and heat drying is performed at the time when the electroless copper plating is completed. Further, electrolytic copper plating is performed to form the metal layer 5. It formed and the multilayer board was obtained. The heating after forming the metal layer 5 was not performed.

(Comparative Example 2) Comparative Example 1 except that heating and drying were not carried out at the time of completion of electroless copper plating.
A multilayer board was obtained in the same manner as in. About the multilayer boards obtained in Examples 1 to 4 and Comparative Examples 1 to 2, the adhesion strength of the metal layer 5 was measured as the peel strength based on JIS C 6481, and the heat resistance when heated at 230 ° C. for 30 minutes. The sex was measured. The results are shown in Table 1. The evaluation of heat resistance is "○" when no blisters are visually observed,
There are 3 blisters with a diameter of less than 1 mm within the range of 5 cm x 5 cm.
"△" when observed within 5 pieces, when 4 or more blisters with a diameter of less than 1 mm were observed within a range of 5 cm x 5 cm, or when it was observed that blisters with a diameter of 1 mm or more were observed. It was judged as ".

[0033]

[Table 1]

As shown in Table 1, each of the examples in which the metal layer 5 is formed by plating the thermosetting resin layer 4 in the semi-cured state is a fully cured thermosetting resin layer. Four
It is confirmed that the adhesion strength of the metal layer 5 is higher than that of each comparative example in which the metal layer 5 is formed by plating. Further, as is clear from the comparison between Examples 1 to 3 and Example 4, and Comparative Example 1 and Comparative Example 2, it is confirmed that heat resistance is enhanced by performing drying after electroless copper plating.

Example 5 FR-4 type having a thickness of 80 μm
The epoxy resin film of m was laid over the surface of the same inner layer circuit board 2 as in Example 1 on the side where the wiring pattern 1 was provided.
By applying heat and pressure under the conditions of 0 ° C., 40 kg / cm ² , and 60 minutes, the inner layer circuit board 2 has a thickness of 70 μm.
The thermosetting resin layer 4 in the semi-cured state was formed.

Next, the inner layer circuit board 2 was subjected to a chemical etching treatment to roughen the surface of the thermosetting resin layer 4.
The chemical etching treatment is performed at 80 ° C. with a “MLB211” solution manufactured by Shipley Co., which is a diethylene glycol-based aqueous solution.
After dipping the inner layer circuit board 2 under the condition of 30 minutes for swelling treatment, the inner layer circuit board 2 is immersed under the condition of 80 ° C. for 30 minutes in the “MLB213” liquid manufactured by Shipley Co. containing potassium permanganate. It was subjected to oxidative decomposition treatment, washed with water, immersed in a 10% sulfuric acid aqueous solution for 5 minutes to neutralize the treatment liquid residue, and further washed with water.

After the chemical etching treatment as described above, the inner layer circuit board 2 is kept at room temperature 2 before copper plating.
The thermosetting resin layer 4 of the inner layer circuit board 2 was dried by leaving it in an atmosphere of 5 ° C. and a relative humidity of 80% for 48 hours. After drying, the glass transition temperature of the thermosetting resin layer 4 in the semi-cured state was measured and found to be 70 ° C.

Next, in the same manner as in Example 1, electroless copper plating is performed on the surface of the thermosetting resin layer 4, and heat drying is performed when the electroless copper plating is completed, and electrolytic copper plating is further performed. The metal layer 5 was formed. After that, Example 1
The thermosetting resin layer 4 was sufficiently cured by heat treatment in the same manner as described above to obtain a multilayer board for a multilayer printed wiring board. When the glass transition temperature of the thermosetting resin layer 4 after curing was measured, it was 140 ° C., which was the maximum glass transition temperature.

Example 6 A multilayer board was obtained in the same manner as in Example 5 except that after the chemical etching treatment (before copper plating), the drying was not carried out. (Example 7) A multilayer board was obtained in the same manner as in Example 5 except that the drying was not performed at the time when the electroless copper plating was completed.

Example 8 Example 5 was repeated except that after the chemical etching treatment (before the copper plating), the drying was not performed, and the drying at the time when the electroless copper plating was completed was not performed.
A multilayer board was obtained in the same manner as in. (Example 9) Circuit board 2 for inner layer made of epoxy resin film
In the same manner as in Example 5 except that the heating and pressurizing conditions when the thermosetting resin layer 4 in the semi-cured state is provided by overlapping the layers with each other are set to 150 ° C., 40 kg / cm ² , and 120 minutes. I got a plate. In Example 9, the glass transition temperature of the semi-cured thermosetting resin layer 4 before electroless copper plating is 9
It was 0 ° C.

(Embodiment 10) An epoxy resin film is laid on the circuit board 2 for the inner layer and the thermosetting resin layer 4 in a semi-cured state.
The heating and pressurizing conditions for the installation are 150 ° C., 40 kg / c
m ² was set to 120 minutes, and a multilayer board was prepared in the same manner as in Example 5 except that after chemical etching (before copper plating), drying was performed at 60 ° C. for 3 hours. Obtained. In Example 10, the glass transition temperature of the semi-cured thermosetting resin layer 4 before the electroless copper plating was 110 ° C.

Comparative Example 3 The same inner layer circuit board 2 as in Example 1 is used, and the same epoxy resin film as in Example 5 is used, and the epoxy resin film is provided on the side of the inner layer circuit board 2 on which the wiring pattern 1 is provided. Layered on the surface, 170 ℃, 4
The thermosetting resin layer 4 having a thickness of 70 μm was formed on the surface of the inner layer circuit board 2 by applying heat and pressure under the conditions of 0 kg / cm ² and 90 minutes. The glass transition temperature of the thermosetting resin layer 4 was measured to be 140 ° C., and the thermosetting resin layer 4 was almost completely cured until the maximum glass transition temperature was reached. Thereafter, the thermosetting resin layer 4 is roughened by chemical etching in the same manner as in Example 5, and then the inner layer circuit board 2 is placed at room temperature of 25 ° C. in the same manner as in Example 5.
It is left to dry in an atmosphere of 80% relative humidity for 48 hours, and electroless copper plating is performed on the surface of the thermosetting resin layer 4 in the same manner as in Example 5 and heat drying is performed when the electroless copper plating is completed. Then, electrolytic copper plating was performed to form a metal layer 5 to obtain a multilayer board. The heating after forming the metal layer 5 was not performed.

(Comparative Example 4) A multilayer board was obtained in the same manner as in Comparative Example 3 except that after the chemical etching treatment (before copper plating), the drying was not carried out. (Comparative Example 5) A multilayer board was obtained in the same manner as in Comparative Example 3 except that the drying was not performed at the time of finishing the electroless copper plating.

(Comparative Example 6) Comparative Example 3 except that the drying after the chemical etching treatment (before the copper plating) is not performed and the drying is not performed at the time when the electroless copper plating is completed.
A multilayer board was obtained in the same manner as in. With respect to the multilayer plates obtained in Examples 5 to 10 and Comparative Examples 3 to 6, the adhesion strength and heat resistance of the metal layer 5 were measured. Table 2 shows the results.

[0045]

[Table 2]

As shown in Table 2, each of the examples in which the metal layer 5 is formed by plating the thermosetting resin layer 4 in the semi-cured state is a fully cured thermosetting resin layer. Four
It is confirmed that the adhesion strength of the metal layer 5 is higher than that of each comparative example in which the metal layer 5 is formed by plating. Further, Examples 5, 9, 10 and Examples 6-8,
As is clear from the comparison between Comparative Example 3 and Comparative Examples 4 to 6, it was confirmed that heat resistance is enhanced by performing drying after chemical etching (before copper plating) or after electroless copper plating. To be done.

(Example 11) FR-4 type epoxy resin (bisphenol A type epoxy resin manufactured by Toho Kasei Co., Ltd.)
Was dissolved in a mixed solvent of MEK and DMF at a ratio of 2: 1 to prepare an epoxy resin varnish having a concentration of 40% by weight, and the epoxy resin varnish was provided on the side where the wiring pattern 1 of the same inner layer circuit board 2 as in Example 1 was provided. It was applied to the surface of using a curtain coater. Then, after heating at 110 ° C. for 30 minutes to remove the solvent, by heating at 150 ° C. for 60 minutes to proceed with curing, the surface of the inner layer circuit board 2 is thermally cured in a semi-cured state with a thickness of 70 μm. The resin layer 4 was formed.

Next, this inner layer circuit board 2 is subjected to a chemical etching treatment in the same manner as in Example 5 to perform thermosetting resin layer 4.
The surface of was roughened. After the chemical etching treatment, the thermosetting resin layer 4 of the inner layer circuit board 2 was dried by allowing the inner layer circuit board 2 to stand in an atmosphere of room temperature of 25 ° C. and relative humidity of 80% for 48 hours. After drying, the glass transition temperature of the thermosetting resin layer 4 in the semi-cured state was measured and found to be 70 ° C.

Next, in the same manner as in Example 1, electroless copper plating is performed on the surface of the thermosetting resin layer 4, and when the electroless copper plating is completed, heat drying is performed, and electrolytic copper plating is further performed. The metal layer 5 was formed. After that, Example 1
The thermosetting resin layer 4 was sufficiently cured by heat treatment in the same manner as described above to obtain a multilayer board for a multilayer printed wiring board. When the glass transition temperature of the thermosetting resin layer 4 after curing was measured, it was 140 ° C., which was the maximum glass transition temperature.

(Embodiment 12) After heating the epoxy resin varnish on the surface of the inner layer circuit board 2, the heating conditions for proceeding the curing were changed to 150 ° C. for 90 minutes, and after chemical etching treatment (copper plating). Before drying, 50 to
rr, except that the pressure was reduced under the condition of 5 hours,
A multilayer board was obtained in the same manner as in Example 11. In Example 12, the glass transition temperature of the semi-cured thermosetting resin layer 4 before the electroless copper plating was 90 ° C.

(Embodiment 13) After heating the epoxy resin varnish on the surface of the inner layer circuit board 2, the heating conditions for curing are changed to 150 ° C. for 120 minutes, and after chemical etching treatment (copper plating). A multilayer board was obtained in the same manner as in Example 11 except that the drying in (1) above was performed by centrifugal dehydration under the conditions of 500 rpm and 3 hours using a centrifugal dehydrator. The glass transition temperature of the semi-cured thermosetting resin layer 4 before electroless copper plating in Example 13 was 110 ° C.

(Comparative Example 7) The same inner layer circuit board 2 as in Example 1 was used, and the same epoxy resin varnish as in Example 11 was used. This epoxy resin varnish was applied to the inner layer circuit board 2 on which the wiring pattern 1 was provided. The surface was coated with a curtain coater. And 3 at 110 ° C for solvent removal
After heating for 0 minutes, 170 ° C. and 90 ° C. for curing.
By heating under the condition of minutes, the thermosetting resin layer 4 having a thickness of 70 μm was formed on the surface of the inner layer circuit board 2. The glass transition temperature of the thermosetting resin layer 4 was measured to be 140 ° C., and the thermosetting resin layer 4 was almost completely cured until the maximum glass transition temperature was reached. After that, a multilayer board was obtained in the same manner as in Example 11 except that after the chemical etching treatment (before copper plating), the drying was not performed, and the drying at the time when the electroless copper plating was completed was not performed.
The heating after forming the metal layer 5 was not performed.

With respect to the multilayer boards obtained in Examples 11 to 13 and Comparative Example 7, the adhesion strength and heat resistance of the metal layer 5 were measured. The results are shown in Table 3.

[0054]

[Table 3]

As shown in Table 3, each of the examples in which the thermosetting resin layer 4 in the semi-cured state is plated to form the metal layer 5 is a fully cured thermosetting resin layer. Four
It is confirmed that the adhesion strength of the metal layer 5 is higher than that of Comparative Example 7 in which the metal layer 5 is formed by plating. Further, as is clear from the comparison between each Example and Comparative Example 7, it was confirmed that heat resistance is enhanced by performing drying after chemical etching (before copper plating) or after electroless copper plating. It

[0056]

As described above, according to the present invention, a thermosetting resin layer having a rough surface is provided on the surface of an inner layer circuit board on which a wiring pattern has been formed. When manufacturing a multilayer printed wiring board having a step of plating the surface with a metal layer for forming a conductor circuit, the thermosetting resin layer is formed of a semi-cured resin and the thermosetting resin is used. Since the degree of curing of the resin of the thermosetting resin layer is increased after metal plating is performed on the surface of the layer, compared with the case of plating the metal layer on the thermosetting resin layer formed by sufficient curing. The adhesive strength of the metal layer to the thermosetting resin layer can be increased.

Further, in the invention of claim 2, the glass transition temperature of the resin of the thermosetting resin layer in the semi-cured state is a temperature lower by 20 ° C. or more than the maximum glass transition temperature reached after increasing the curing degree. By setting the semi-cured state of the thermosetting resin layer in this way, it is possible to sufficiently improve the adhesion strength of the metal layer to the thermosetting resin layer.

Further, according to the invention of claims 3 to 6, the thermosetting resin layer is dried at room temperature before the thermosetting resin layer is plated with metal, or the glass transition of the resin of the thermosetting resin layer is performed. It is characterized by heating at a temperature lower than the temperature to dry the thermosetting resin layer, or drying the thermosetting resin layer under reduced pressure, or centrifugal dehydration to dry the thermosetting resin layer. When the surface of the thermosetting resin layer is roughened, the water of the thermosetting resin layer can be removed by drying these even if the water is absorbed by the thermosetting resin layer. The heat resistance can be improved by preventing swelling of the metal layer due to moisture absorbed in the layer and the like.

The invention according to claim 7 is characterized in that, when the metal plating is carried out by electroless plating and electrolytic plating subsequent to electroless plating, the thermosetting resin layer is dried after the electroless plating is carried out. That is, even when moisture is absorbed by the thermosetting resin layer during electroless plating, the moisture of the thermosetting resin layer can be removed by drying, and the moisture absorbed by the thermosetting resin layer The heat resistance can be improved by preventing swelling of the metal layer and the like.

[Brief description of drawings]

FIG. 1 shows an example of an embodiment of the present invention,
(A) thru | or (e) are each a schematic front view.

[Explanation of symbols]

 1 Wiring Pattern 2 Inner Layer Circuit Board 3 Rough Surface 4 Thermosetting Resin Layer 5 Metal Layer 6 Conductor Circuit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shingo Yoshioka 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Inventor Hajime Sugiyama 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works Co. 72) Inventor Koji Takagi 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Inventor Shinichi Iketani 1048 Kadoma, Kadoma City Matsushita Electric Works Co., Ltd. (72) Inventor Hiroaki Fujiwara Osaka 1048 Kadoma, Kadoma City, Matsushita Electric Works Co., Ltd. (72) Inventor, Kiyoaki Ihara, 1048 Kadoma, Kadoma City, Osaka Prefecture Osaka, Ltd. (72), Satoru Ogawa, 1048 Kadoma, Kadoma City, Osaka Matsushita Denko stock company

Claims (7)

[Claims] 1. A thermosetting resin layer having a rough surface is provided on the surface of an inner layer circuit board on which a wiring pattern has been formed, and a metal plating is applied to the surface of the thermosetting resin layer to form a conductor. When manufacturing a multilayer printed wiring board having a step of providing a metal layer for forming a circuit, a thermosetting resin layer is formed of a semi-cured resin, and the surface of the thermosetting resin layer is plated with metal. A method for manufacturing a multilayer printed wiring board, comprising increasing the degree of curing of the resin of the thermosetting resin layer after curing. 2. The glass transition temperature of the resin of the thermosetting resin layer in the semi-cured state is 20 ° C. or more lower than the maximum glass transition temperature reached after increasing the curing degree. 1. The method for manufacturing a multilayer printed wiring board according to 1. 3. The method for producing a multilayer printed wiring board according to claim 1, wherein the thermosetting resin layer is dried at room temperature before metal plating is applied to the thermosetting resin layer. 4. The thermosetting resin layer is dried by heating at a temperature lower than the glass transition temperature of the resin of the thermosetting resin layer before metal plating the thermosetting resin layer. The method for manufacturing a multilayer printed wiring board according to claim 1. 5. The method for producing a multilayer printed wiring board according to claim 1, wherein the thermosetting resin layer is dried under reduced pressure before metal plating is applied to the thermosetting resin layer. 6. The method for producing a multilayer printed wiring board according to claim 1, wherein the thermosetting resin layer is dried by centrifugation before the metal plating is applied to the thermosetting resin layer to dry the thermosetting resin layer. . 7. The thermosetting resin layer is dried after performing electroless plating when performing metal plating by electroless plating and electrolytic plating subsequent to electroless plating. A method of manufacturing a multilayer printed wiring board according to claim 1.