JPH0644676B2 - Method for manufacturing multilayer wiring board - Google Patents

Description

The present invention relates to a method for manufacturing a multilayer wiring board. More specifically, the present invention relates to a method for manufacturing a new multilayer wiring board, which can improve the adhesive force between an inner layer material and a prepreg layer and improve the reliability of a wiring board having a fine circuit.

(Prior Art) Regarding printed wiring boards used in electric / electronic devices, electronic computers, communication devices, etc., the demand for multilayer wiring boards has increased along with the increasing demand for high-density mounting in recent years. Various efforts have been made to improve the reliability of multilayer wiring boards.

Conventionally, as for a printed wiring board having such a multilayer structure, for example, as shown in FIG. 2, an inner layer material (a) having a circuit (a) formed on a copper foil surface of a single-sided or double-sided copper clad laminate is used. ), The surface of the inner layer material (a) is physically roughened by a sander, a belt sander, or the like, or after this roughening, the surface of the copper foil circuit (a) is blackened by treatment with an alkaline sodium chlorite aqueous solution or the like. After the blackening treatment to form a copper oxide film, a single-sided copper-clad laminate or copper foil (d) is placed as an outer layer material via a prepreg layer (c) and integrally molded .

(Problems to be Solved by the Invention) Such a conventional manufacturing method can temporarily secure reliability in a circuit having a pattern density up to now, but in a fine pattern circuit in which the circuit density has increased remarkably in recent years, It has become difficult to secure an interlayer adhesive force between the inner layer material (a) and the prepreg layer (c). This is because in the case of a fine pattern circuit, the area occupied by the circuit (a) is significantly larger than the conventional circuit area on the surface of the inner layer material (a) in the printed wiring board. ) The contact area between the resin layer and the prepreg layer (c) is decreasing, and even if the copper foil circuit (a) is surface-treated as in the conventional case, deterioration of interlayer adhesion on this contact surface can be avoided. Absent.

For this reason, the interlayer adhesive force is lowered by the conventional manufacturing method, and the occurrence of halo and the reduction in reliability of the wiring board cannot be avoided.

As a solution to such a problem, a method of reducing the surface of the inner layer material (a) after blackening is proposed, but this method requires the use of a special aminoborane compound, The effect was not always satisfactory.

The present invention has been made in view of the circumstances as described above, and improves the drawbacks of the conventional method for manufacturing a multilayer wiring board, and even if the circuit area of the fine pattern circuit, that is, the inner layer material surface is large, the interlayer adhesiveness is improved. It is an object of the present invention to provide a new manufacturing method capable of manufacturing a multi-layer wiring board having excellent halo resistance, excellent halo resistance, and improved reliability.

(Means for Solving the Problems) As a solution to the above problems, the present invention provides a copper oxide layer formed by oxidizing the copper circuit surface of an inner layer circuit board to a low oxidation state by contact with a reducing flame. The present invention provides a method for manufacturing a multilayer wiring board, characterized in that the outer layer material is laminated and integrally molded with a roughened surface, and then a prepreg is interposed.

The reducing flame used in the present invention is generated by the combustion of gas serving as a fuel by a burner or the like, and is a reducing flame containing no hydrogen, carbon monoxide or the like.

By passing through the inner layer circuit board having the copper oxide layer formed on the surface in such a reducing flame, the reducing flame is reduced to CuO, C
The copper oxide layer of uO ₂ O is contacted. This contact is preferably made instantaneously, and more preferably, the copper oxide layer is reduced to a low-level oxidation state by passing through the reducing flame for about 3 seconds or less. By this treatment, the surface of the copper circuit is roughened and the adhesive force with the prepreg is further improved.

The contact with the reducing flame can also be performed by burning the solvent on the surface of the circuit board.

A method for manufacturing a multilayer wiring board according to the present invention will be described with reference to FIG. 1 of the accompanying drawings.

(a) The copper circuit (1) surface of the inner layer material (2) having the copper circuit (1) on one or both sides formed from prepreg, copper foil, etc. is oxidized to form a copper oxide layer of CuO, Cu ₂ O. (3)
To form.

At this time, the type of the prepreg for forming the inner layer material (2) is not limited in some cases, and a material such as glass cloth or paper impregnated with a resin such as phenol, epoxy, polyimide or unsaturated polyester is appropriately used. Can be used.

For these prepregs, for example, an appropriate number of 1 to 3 can be used.

Oxidation of the copper circuit (1) can be performed by a conventionally known method such as blackening treatment or by oxidation in a vapor phase. Depending on the processing at this time, Cu
A copper oxide layer (3) of O or Cu ₂ O or its coexistence state is formed.

The copper oxide layer (3) is then reduced in oxidation level by contact with a reducing flame.

(b) Then, a desired number of prepregs (4) and the outer layer material (5) are arranged on the obtained surface to be laminated and integrated.

The prepreg (4) is preferably arranged, for example, about 1 to 3, but not limited to this. As the prepreg (4), similar to the case of the inner layer material (2), cloth or mat-like material such as glass cloth, aramid cloth, polyester cloth, or epoxy resin, phenol resin, polyimide resin as a base material such as nonwoven fabric or paper. Those impregnated with a resin such as can be used. Among them, the glass cloth epoxy resin prepreg is exemplified as a suitable one. Further, as the outer layer material (5), copper foil,
Alternatively, a one-sided copper clad laminate made of prepreg and copper foil can be used.

The laminated integral molding can be appropriately carried out according to conventionally known methods and conditions such as multi-stage pressing, styrene, double belt, and pressureless continuous heating. A multilayer circuit board is manufactured by forming a circuit on the outermost copper foil of the laminated board integrated by this molding.

Needless to say, the details of the above manufacturing conditions and the like can be variously modified, including known ones.

(Operation) In the present invention, the copper circuit surface is roughened by the oxidation treatment of the copper circuit surface of the inner layer material and the reduction treatment of the oxidation level of the surface copper oxide layer formed by this oxidation treatment by reducing flame contact. As a result, the interlayer adhesion between the inner layer material and the prepreg is greatly improved, and excellent halo resistance is realized.

Examples will be shown below to describe the method for producing a multilayer board of the present invention in more detail.

(Example) Example 1 A circuit was formed on both sides of a double-sided copper-clad glass epoxy resin laminate having a thickness of 1 mm, and this was used as an inner layer material.

After washing with water, NaClO ₄ , NaOH and Na ₂ PO ₄
It was treated with an aqueous solution of 2H ₂ O to form a CuO layer on the circuit surface.

Then, the CuO layer was reduced by passing it through a gas reducing flame instantaneously. Then, it was washed with water and dried.

Two 0.1 mm thick glass cloth epoxy resin prepregs were provided on each of the upper and lower surfaces of the inner layer material, and a 0.035 mm thick copper foil was provided as the outermost layer.

This laminate was laminated and molded at a pressure of 40 kg / cm ² and a temperature of 165 ° C. for 60 minutes to obtain a four-layer circuit printed wiring board.

When the interlayer adhesion and the halo resistance of this wiring board were evaluated, the results shown in Table 1 were obtained. From the comparison with Comparative Examples described later, it was confirmed that the interlayer adhesive force was improved and the halo resistance was remarkably improved.

The halo resistance was evaluated by immersion in a 1: 1 HCl solution for 30 minutes.

Example 2 A wiring board was manufactured in the same manner as in Example 1 except that a Cu ₂ O layer was formed on the circuit surface, and the halo resistance was evaluated. The results are shown in Table 1.

Excellent halo resistance was obtained.

Example 3 A slight amount of methanol was applied to the circuit board having the CuO layer on the surface prepared in Example 1, and after 3 seconds from ignition, it was put into water to extinguish the fire.

This was similarly made into a multilayer board and evaluated for halo resistance.

The halo resistance was good.

Comparative Example 1 A multilayer wiring board was manufactured without performing oxidation and reducing flame treatment on the surface of a copper circuit. When the halo resistance was evaluated, it was far inferior to the examples.

Comparative Example 2 A Cu ₂ O layer was formed by blackening treatment, and a multilayer board was manufactured as it was. The halo resistance was inferior.

[Effects of the Invention] As described in detail above, the method for manufacturing a multilayer wiring board according to the present invention realizes a multilayer wiring board with greatly improved interlayer adhesion and halo resistance.

It is possible to improve the reliability of a multilayer wiring board having a fine pattern circuit.

[Brief description of drawings]

FIG. 1 is a process cross-sectional view illustrating a manufacturing process of a method for manufacturing a multilayer wiring board according to the present invention. FIG. 2 is a process sectional view showing a conventional manufacturing method. 1 ... Copper circuit 2 ... Inner layer material 3 ... Copper oxide layer 4 ... Prepreg 5 ... Outer layer material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiyuki Akamatsu 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (56) References JP-A-56-35497 (JP, A) JP-A-57-177593 (JP, A)

Claims (2)

[Claims] 1. A copper oxide layer formed by oxidizing the copper circuit surface of an inner layer circuit board is roughened to a low oxidation state by contact with a reducing flame, and then an outer layer material is laminated and integrated by interposing a prepreg. A method for manufacturing a multilayer wiring board, which comprises molding. 2. The manufacturing method according to claim 1, wherein the copper oxide layer on the surface of the copper circuit is brought into a low oxidation state by contact with a reducing flame within 3 seconds.