JPH05235548A - Manufacture of multilayer printed circuit board - Google Patents

Abstract

PURPOSE:To enhance adhesive properties of a copper circuit of a circuit board for an inner layer with resin to a high level. CONSTITUTION:Hydroxyl group is applied to a surface of a copper circuit provided on a circuit board for an inner layer. Resin-impregnated base material is superposed on the board through coupling agent and multilayer-laminated to manufacture a multilayer printed circuit board. Bonding strength of the surface of the copper circuit to the agent is enhanced by coupling the hydroxyl group to the agent, thereby enhancing an effect of improving adhesive properties of the circuit with the resin of the base material by the agent.

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 used in electronic equipment and the like.

[0002]

2. Description of the Related Art In a multilayer printed wiring board, an outer layer circuit board or a copper foil is laminated on a circuit board for an inner layer having a circuit formed of copper foil or the like on one side or both sides through a resin-impregnated base material (prepreg). Is generally formed by laminating and forming an inner layer circuit board and an outer layer circuit board or a copper foil via an insulating adhesive layer made of a resin-impregnated base material.
In this multilayer printed wiring board, it is necessary to secure the adhesiveness between the copper circuit formed on the circuit board for the inner layer and the resin of the resin-impregnated base material on which the circuit board for the outer layer or the copper foil is laminated.

Therefore, it has been studied to improve the adhesiveness between the copper circuit and the resin by various methods. For example, a cupric oxide (CuO) film is formed on the surface of the copper circuit by oxidizing the copper circuit. It is commonly done to form and enhance adhesion. Fine protrusions will be formed on the surface of the cupric oxide coating obtained by oxidizing copper,
The surface of the copper circuit can be roughened by the unevenness due to the fine projections, and the adhesiveness between the copper circuit and the resin can be enhanced.

However, since cupric oxide formed on the surface by oxidizing a copper circuit is easily dissolved in acid, a chemical plating solution or a chemical plating solution is used when through-hole plating is performed on a through-hole processed into a multilayer printed wiring board. When immersed in the electroplating solution, the cupric oxide in the cross-section of the copper circuit exposed at the inner periphery of the through hole dissolves in the acid of the plating solution, and the acid between the inner periphery of the through hole and the interface between the copper circuit and the resin is removed. There is a possibility that a so-called halo phenomenon occurs in which infiltration dissolution erosion occurs.
In recent years, the distance between through-holes and between through-holes and wiring circuits has tended to decrease as the packaging density increases, and such a halo phenomenon is a serious problem that reduces reliability of multilayer printed wiring boards. It will be.

Therefore, in order to deal with such a problem,
While a method for preventing the occurrence of a halo phenomenon by reducing cupric oxide to a state in which it is insoluble in acid is being studied, a method for improving adhesion without oxidizing a copper circuit is also being studied. The method provided in Japanese Patent Application Laid-Open No. 2-277294 is the latter method, in which the surface of the copper circuit is roughened by buffing, soft etching, etc. without oxidizing the surface of the copper circuit. It is treated with a coupling agent, and this coupling agent enhances the adhesiveness between the copper circuit and the resin of the prepreg.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
By using a coupling agent as provided in Japanese Patent No. 294, the adhesion between the copper circuit and the resin can be increased to some extent. However, it is hard to say that the level has reached a satisfactory level simply by using the coupling agent. It is considered that this is because the binding force between the resin and the coupling agent is strong, but the binding force between the coupling agent and the copper circuit is weak.

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 increasing the adhesion between a copper circuit and a resin to a high level. It is a thing.

[0008]

A method for manufacturing a multilayer printed wiring board according to the present invention comprises a step of imparting a hydroxyl group to the surface of a copper circuit provided on a circuit board, and then applying this to the circuit board via a coupling agent. The invention is characterized in that resin-impregnated base materials are stacked to form a multilayer laminate. In the present invention, a hydroxyl group can be imparted to the surface of the copper circuit by treating with a metal alcoholate or by treating with an alkali.

In the present invention, it is preferable to use a silane coupling agent as the coupling agent. Hereinafter, the present invention will be described in detail. As the circuit board used as the circuit board for the inner layer, a copper clad glass-epoxy resin laminated board on which a copper foil is stretched, or a copper circuit such as a copper clad glass-polyimide resin laminated board is subjected to an etching treatment or the like to form a copper circuit on one or both sides. It is also possible to use a laminate having a copper circuit formed on one side or both sides by chemical plating or electroplating, or the like. Then, it is preferable that the surface of the circuit board is first roughened. The roughening treatment can be carried out by buffing, chemical treatment such as soft etching, electrolytic treatment, liquid honing, etc., or a combination thereof. This roughening treatment may be performed on the copper foil before the circuit formation or on the copper circuit after the circuit formation.

After the surface of the circuit board has been roughened as described above, a process of imparting a hydroxyl group (OH group) to the surface of the copper circuit is performed. The treatment for imparting a hydroxyl group to the surface of the copper circuit is not particularly limited, but it can be performed by treating the surface of the copper circuit with a metal alcoholate. As the metal alcoholate, sodium methylate (CH ₃ ONa), sodium ethylate (C
₂ H ₅ ONa), lithium ethylate (C ₂ H ₅ OL
i) or the like can be used, and the treatment can be performed by immersing the circuit board in a solution of these metal alcoholates or by spraying the solution on the surface of the circuit board. Of course, the method of treatment is not limited to these.

Hydroxyl groups can also be added to the surface of the copper circuit by treating the surface of the copper circuit with alkali. As the alkali, sodium hydroxide or potassium hydroxide can be used, and the treatment can be performed by immersing the circuit board in these alkali solutions or spraying the alkali solution on the surface of the circuit board. it can. Of course, the method of treatment is not limited to these.

Further, immediately after polishing the surface of the copper circuit, it is possible to add a hydroxyl group to the surface of the copper circuit by subjecting it to humidification or steam treatment. These methods can also be used together to impart a hydroxyl group to the surface of the copper circuit, but the treatment is intended to impart only a hydroxyl group to the surface of the copper circuit. No oxide film should be formed. From this point of view, as a method of imparting only a hydroxyl group, a method of treating with a metal alcoholate and a method of treating with an alkali are preferable.

After the surface of the copper circuit is treated with a hydroxyl group as described above, the surface of the copper circuit is treated with a coupling agent to attach the coupling agent. As the coupling agent, γ-aminopropyltriethoxysilane,
It is preferable to use a silane coupling agent such as N-β-aminoethyl γ-aminopropyltrimethoxysilane or N-phenyl-γ-aminopropyltrimethoxysilane. The coupling agent is used by diluting it with alcohol such as ethanol or isopropyl alcohol.
Although the concentration is not limited, it is preferably about 0.1 to 30% by volume. In addition, a small amount of acid such as acetic acid or hydrochloric acid may be added to accelerate the hydrolysis of the coupling agent. Then, the treatment with the coupling agent is performed by immersing the circuit board in the coupling agent solution, spraying the coupling agent solution on the surface of the circuit board, and applying the coupling agent on the surface of the copper circuit. It can be done. When the coupling agent is applied to the surface of the copper circuit in this way, since the hydroxyl group is added to the surface of the copper circuit as described above, the coupling agent reacts with this hydroxyl group and the coupling agent and the copper It is possible to increase the binding force by increasing the reactivity with the surface of the circuit.

The circuit board thus treated with the coupling agent is naturally dried, heat dried, or vacuum dried, and then
By using this circuit board as the circuit board for the inner layer, a multilayer printed wiring board can be manufactured in a usual process. That is, a resin-impregnated base material (prepreg) is obtained by impregnating a base material such as a glass cloth with a thermosetting resin such as an epoxy resin, a polyimide resin, a cyanate ester resin or a modified resin thereof alone or in combination, and heating and drying. Create and overlay the circuit board for outer layer (or other circuit board for inner layer) or copper foil with resin impregnated base material on the circuit board,
By heat-pressurizing this and laminating-molding it, a multilayer board in which the resin-impregnated base material is laminated in multiple layers as an insulating adhesive layer can be obtained. In this multi-layer board, the surface of the copper circuit of the circuit board is coated with a coupling agent, so the surface of the copper circuit and the resin of the resin-impregnated base material are bonded by the chemical crosslinking effect of the coupling agent. It is possible to improve the sex. A multilayer printed wiring board can be manufactured by forming through holes in this multilayer board by drilling, performing through-hole plating by chemical plating or the like, and further performing processing such as etching to form an outer layer circuit. It is a thing.

In the above-mentioned example, after the hydroxyl group is given to the surface of the copper circuit of the circuit board, the coupling agent is further applied to the surface of the copper circuit for the treatment. The treatment may be performed on the resin-impregnated base material. For example, by immersing the resin-impregnated base material in the coupling agent solution, or by spraying the coupling agent solution on the surface of the resin-impregnated base material,
A coupling agent can be applied to the adhesive surface of the resin-impregnated base material with the copper foil. Then, the resin-impregnated base material treated with the coupling agent in this manner is further treated with a coupling agent after the circuit board which has been subjected to the treatment for imparting a hydroxyl group to the surface of the copper circuit, or the treatment for imparting a hydroxyl group to the surface of the copper circuit. A multilayer printed wiring board in which the resin-impregnated base material is laminated in multiple layers as an insulating adhesive layer can be obtained by stacking on the treated circuit board and performing multilayer lamination molding in the same manner as above.

It is also possible to use an adhesive layer made of a resin containing a coupling agent. That is, a circuit board that has been subjected to a hydroxyl group-providing treatment on the surface of the copper circuit, or a circuit board that has been further treated with a coupling agent after the treatment to impart a hydroxyl group on the surface of the copper circuit and the resin-impregnated base material An adhesive layer made of a resin containing a coupling agent is provided, and a multilayer printed wiring board in which a resin-impregnated base material is laminated in multiple layers as an insulating adhesive layer can be obtained by performing multilayer lamination molding in the same manner as above.
This adhesive layer is applied on the surface of the circuit board, applied on the surface of the resin-impregnated base material, or formed into a film and sandwiched between the circuit board and the resin-impregnated base material. It can be provided.

Further, a resin-impregnated base material prepared by impregnating and drying a base material with a resin varnish containing a coupling agent in an amount of 0.01 to 30% by weight based on the solid content of the resin can be used. A resin-impregnated base material containing this coupling agent, a circuit board that has been subjected to a hydroxyl group-providing treatment on the surface of the copper circuit, or a circuit that has been further treated with a coupling agent after the treatment to impart a hydroxyl group on the surface of the copper circuit. Stack on a board,
By carrying out multi-layer lamination molding in the same manner as described above, a multi-layer printed wiring board in which resin-impregnated base materials are laminated in multiple layers as an insulating adhesive layer can be obtained.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples. (Example 1) 150 m formed by applying a 35 μm thick copper foil on both sides
After buffing and roughening the copper foil surface of the m × 150 mm × 0.7 mm glass cloth substrate epoxy resin laminate,
A circuit board for an inner layer was prepared by etching a copper foil to form a copper circuit. Next, a metal alcoholate treatment bath having a composition of CH ₃ OH ... 1 liter CH ₃ ONa ... 35 g water ... 65 cc was prepared at 30 ° C., and the circuit board was immersed in this treatment bath for 3 minutes to hydrate the surface of the copper circuit with sodium. It was treated with methylate to give hydroxyl groups to the surface of the copper circuit. After this, wash the surface of the circuit board with water,
It was dried at 80 ° C. for 1 hour. Next, a coupling agent solution having a composition of γ-aminopropyltriethoxysilane ... 40 cc isopropyl alcohol ... 1 liter was prepared, and the coupling agent solution was placed in a vertical dip tank, and the inner layer circuit board treated with was dipped. The coupling agent was treated by immersing it at a speed of 300 mm / min for 1 minute. After the treatment, the circuit board was naturally dried for 1 hour and further dried at 80 ° C. for 3 hours. On both surfaces of the inner layer circuit board treated as described above, a 0.1 mm thick glass cloth base epoxy resin prepreg 3
A multilayer board having a four-layer circuit structure was obtained by stacking the sheets one by one, and further stacking a copper foil having a thickness of 18 μm on the outer side thereof, and performing secondary lamination molding under the conditions of 170 ° C., 40 kg / cm ² , and 120 minutes.

(Example 2) The coupling agent solution of the step of Example 1 was prepared and used with a composition of N-β aminoethyl γ aminopropyltrimethoxysilane ... 40 cc isopropyl alcohol ... 1 liter, and the rest was carried out. A multilayer board having a four-layer circuit structure was obtained in the same manner as in Example 1.

(Example 3) The coupling agent solution of the step of Example 1 was prepared by: γ-aminopropyltriethoxysilane ... 40 cc Isopropyl alcohol ... 1 liter 0.05N-HCl aqueous solution ... 9.6c
A multilayer board having a four-layer circuit structure was obtained in the same manner as in Example 1 except that the composition c was used.

(Example 4) The coupling agent solution of the step in Example 1 was prepared by: γ-aminopropyltriethoxysilane ... 10 cc Isopropyl alcohol ... 1 liter 0.05N-HCl aqueous solution ... 9.6c
A multilayer board having a four-layer circuit structure was obtained in the same manner as in Example 1 except that the composition c was used.

(Example 5) A circuit board for an inner layer was prepared in the same manner as in Example 1. Next, an alkali treatment bath was prepared at 30 ° C. with a composition of H ₂ O ... 1 liter NaOH ... 40 g, and the circuit board was immersed in this treatment bath for 3 minutes for alkali treatment to give hydroxyl groups to the surface of the copper circuit. did. After this, the surface of the circuit board was washed with water and dried at 80 ° C. for 1 hour. The coupling agent treatment was performed in the same manner as in Example 1. A multilayer board having a four-layer circuit structure was obtained in the same manner as in Example 1.

Example 6 A circuit board for an inner layer was prepared in the same manner as in Example 1. A hydroxyl group was added to the surface of the copper circuit of the circuit board by treating with a metal alcoholate in the same manner as in Example 1. The coupling agent solution prepared in Example 1 was placed in a vertical dip tank, and a glass cloth-based epoxy resin prepreg having a thickness of 0.1 mm was dipped at a speed of 300 mm /
It was treated with a coupling agent by immersing it for 1 minute at min. After the treatment, the prepreg is naturally dried for 1 hour,
Furthermore, it dried at 50 degreeC for 4 hours. The two glass cloth base material epoxy resin prepregs treated with the coupling agent are superposed on both sides of the circuit board treated with the respective glass cloth base material epoxy resin prepregs, and a glass cloth base material epoxy resin prepreg with a thickness of 0.1 mm which is not treated with the coupling agent is provided on each outer side thereof. Two layers were laminated, a copper foil having a thickness of 18 μm was further laminated on the outer side, and then secondary lamination molding was performed under the same conditions as in Example 1 to obtain a multilayer printed wiring board.

(Comparative Example 1) In Example 1, the multilayer printed wiring board was obtained only by the steps of Example 1 and without performing the treatment for applying the hydroxyl group of 1 to the surface of the copper circuit and the treatment with the coupling agent. It was (Comparative Example 2) A circuit board for an inner layer was prepared in the same manner as in Example 1. Next, an etching treatment bath having a composition of CuCl ₂ .2H ₂ O ... 45.6 g H ₂ O ... 800 cc 35% -HCl aqueous solution ... 350 cc was prepared at 30 ° C., and the circuit board was immersed in this etching treatment bath for 1 minute. The surface of the copper circuit was soft-etched. After this, the surface of the circuit board was washed with water and dried at 80 ° C. for 1 hour. The coupling agent treatment was performed in the same manner as in Example 1. A multilayer board having a four-layer circuit structure was obtained in the same manner as in Example 1.

(Comparative Example 3) A circuit board for an inner layer was prepared in the same manner as in Example 1. Next, an oxidant treatment bath having a composition of NaClO ₂ ... 60 g Na ₃ PO ₄ .12H ₂ O ... 10 g NaOH ... 8 g H ₂ O ... 1 liter was prepared at 30 ° C, and a circuit board was placed in this oxidant treatment bath. The surface of the copper circuit was oxidized by immersion for a minute to form a cupric oxide film on the surface of the copper circuit (no coupling agent treatment was performed). A multilayer board having a four-layer circuit structure was prepared in the same manner as in Example 1 by using the circuit board treated in (4).

The multilayer boards obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were tested for copper foil peeling strength, boiling solder heat resistance and hydrochloric acid resistance, and the results are shown in Table 1. The copper foil peeling strength test is carried out by boiling the multi-layer board for two hours and then forming a copper circuit of the inner layer circuit board.
The peeling strength between the μm copper foil and the insulating adhesive layer formed by the prepreg (resin-impregnated base material) was measured. The boiling soldering heat resistance test was performed by evaluating the state when the multilayer board was boiled for 2 hours and then immersed in a solder bath at 260 ° C. for 30 seconds. It was shown by "X". The hydrochloric acid resistance test was conducted by drilling through holes in a multilayer board using a 0.4 mmφ drill bit, and immersing the drilled multilayer board in a 17.4% HCl aqueous solution adjusted to 25 ° C. for 10 minutes. The presence or absence of halo phenomenon in the through hole is evaluated and
The absence of the halo phenomenon is indicated by "○", and the occurrence of the halo phenomenon is indicated by "x".

[0027]

[Table 1]

As shown in Table 1, in each of the examples in which the treatment for forming hydroxyl groups on the surface of the copper circuit was performed,
It is confirmed that the peeling strength of the copper foil is high, the heat resistance of the boiling solder is good, the adhesion between the copper circuit and the resin is improved, and that the halo phenomenon does not occur. On the other hand, the adhesiveness of the copper circuit is extremely low in the case of Comparative Example 1 which is not treated, and the adhesiveness of the copper circuit is sufficiently obtained in the case of Comparative Example 2 in which the treatment is performed by soft etching and coupling agent treatment. However, the halo phenomenon occurs in Comparative Example 3 in which the treatment is performed by the oxidation treatment of the copper circuit.

[0029]

As described above, according to the present invention, the surface of a copper circuit provided on a circuit board is treated with a hydroxyl group, and a resin-impregnated base material is overlaid on the circuit board via a coupling agent to form a multilayer laminate. Since it is molded, it is possible to increase the bonding force between the surface of the copper circuit and the coupling agent by bonding the hydroxyl group and the coupling agent. It is possible to obtain a high effect of improving the adhesiveness between the copper circuit and the resin and to raise the adhesiveness between the copper circuit and the resin to a high level. Further, since it is not necessary to form an oxide film on the surface of the copper circuit, there is no possibility that a halo phenomenon will occur during plating.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tokio Yoshimitsu 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (6)

[Claims] 1. A multi-layer multi-layer molding comprising: subjecting a surface of a copper circuit provided on a circuit board to a treatment for imparting a hydroxyl group, and superposing a resin-impregnated base material on the circuit board via a coupling agent. Manufacturing method of printed wiring board. 2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the surface of the copper circuit is treated with a metal alcoholate to give a hydroxyl group. 3. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the surface of the copper circuit is treated with an alkali to give a hydroxyl group. 4. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the coupling agent is a silane coupling agent. 5. The surface of a copper circuit provided on a circuit board is subjected to a treatment for imparting a hydroxyl group, a coupling agent is applied to the surface of the copper circuit, and a resin-impregnated base material is laid over the circuit board to form a multilayer laminate. The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 4, characterized by being formed. 6. A circuit board, which has been subjected to a treatment for imparting hydroxyl groups to the surface of a copper circuit, and a resin-impregnated base material, which has been treated with a coupling agent, are laminated and molded. 5. The method for manufacturing a multilayer printed wiring board according to any one of 4 above.