JPH02281690A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To improve a multilayer wiring board in interlaminar adhesion even if a circuit formed on the surface of an inner layer becomes large dn area, resistance to halo, and reliability by a method wherein the circuit of an inner material is subjected to a cathode treatment to be roughened, and an outer material is provided onto the inner materiel through the intermediary of a prepreg, which is monolithically molded. CONSTITUTION:The surface of a circuit 1 formed on one side or both the sides of an inner material 2 formed of prepregs and a metal foil of copper or the like is roughened through a cathode treatment. Then, a required number of pieces of prepregs 3 and outer materials are provided onto the roughened surface in lamination and formed into an integral structure. A laminating imonolithical molding is optionally carried out conforming to a condition and a method such as a multi-stage pressing, styrene, a double belt, a non-pressure continuous heating method, and the like. A circuit is formed on the outermost layer metal foil of the monolithically molded laminated body, whereby a multilayer circuit board can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a printed wiring board. More specifically, the present invention relates to a new method for manufacturing a printed wiring board that can improve the adhesiveness between an inner layer material and a prepreg layer and improve the reliability of a multilayer wiring board having a fine pattern circuit.

(Prior art) With regard to printed wiring boards used in electrical and electronic equipment, electronic computers, communication equipment, etc., the demand for multilayer printed wiring boards has increased with the increasing demand for high-density packaging in recent years. Accordingly, various efforts have been made to improve the reliability of multilayer printed wiring boards.

Conventionally, for printed wiring boards having such a multilayer structure, as shown in FIG. ), and sand the surface of this inner layer material (a).
The prepreg is then physically roughened using a belt sander, or after this roughening is treated with an alkaline sodium chlorite aqueous solution to form a black copper oxide film on the surface of the copper foil circuit (A). It has been manufactured by disposing a single-sided copper-clad laminate or silver foil (1) as an outer layer material via layers and integrally molding it.

(Problems to be Solved by the Invention) Although the conventional manufacturing method described above can secure reliability for circuits with conventional pattern densities, it is difficult to achieve reliability in fine pattern circuits where circuit densities have increased significantly in recent years. It has become difficult to ensure interlayer adhesion between the inner layer material (a) and the prepreg layer (t). 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 a printed wiring board. This is because the contact area between the resin layer and the prepreg layer (2) decreases, and even if the copper foil circuit (A) is surface-treated using the conventional method, a decrease in interlayer adhesion at this contact surface is unavoidable. .

For this reason, depending on the conventional manufacturing method, interlayer adhesion deteriorates, and the occurrence of halos and a decrease in reliability of the wiring board are unavoidable.

This invention was made in view of the above circumstances, and it improves the shortcomings of the conventional multilayer printed wiring board manufacturing method. The object of the present invention is to provide a new manufacturing method that has good adhesiveness, excellent halo resistance, and can improve the reliability of multilayer wiring boards.

(Means for Solving the Problem) The present invention solves the above problems by roughening the circuit of the inner layer material by cathodic treatment, and then disposing the outer layer material through the prepreg. Provided is a method for manufacturing a printed wiring board characterized by integrally molding the body.

The manufacturing method of the present invention will now be described in detail with reference to FIG. 1 of the attached drawings.

(a) The surface of the circuit (1) of the inner layer material (2) having the circuit (1) on one or both sides formed from prepreg and metal foil such as copper foil is roughened by cathodic treatment.

The prepreg forming the inner layer material (2) at this time is not particularly limited in its type, and may be a base material such as glass cloth or paper impregnated with a resin such as phenol, epoxy, polyimide, or unsaturated polyester. Also, for the circuit (1), metals and alloys including copper can be used.

For example, about 1 to 3 of these repregs can be used in the shell.

For example, when copper is the target, cathode treatment is performed using copper 5 to
Inner layer material (2) at a temperature of 10 to 50°C with a sulfuric acid/copper sulfate aqueous solution of 60 g/J and 10 to 200 t/J of sulfuric acid.
The circuit (1) is treated as a cathode (all the patterns are conductive) to form a finely uneven rough surface in the circuit (1). Note that if the circuit (1) has independent patterns, they are connected by temporary wiring using conductive paste or the like.

In this case as well, copper borofluoride, copper borofluoride,
An appropriate electrolytic plating solution containing copper ions such as copper sulfamate can be used. Processing time is usually 1-1
The time can be approximately 0 minutes.

(b) Next, the required number of prepregs (3) and outer layer material (4) are placed on the obtained surface and laminated together.

The prepreg (3) is preferably arranged in a thickness of 1 to 3 sheets, for example, but is not particularly limited to this.As the prepreg (4), glass cloth can be used as in the case of the inner layer material (2). A cloth or mat-like material such as , aramid cloth, or polyester cloth, or a base material such as nonwoven fabric or paper impregnated with a resin such as epoxy resin, phenol resin, or polyimide resin can be used.

Among these, glass cloth epoxy resin prepreg is exemplified as a suitable one. In addition, as the outer layer material (4),
Metal foils such as copper, aluminum, and stainless steel, or single-sided metal-clad laminates made of prepreg and these metal foils can be used. Of these, the outer layer material (4
) is exemplified as one of the preferred ones using copper foil.

The lamination and integral molding can be carried out as appropriate using conventionally known methods and conditions such as multistage press, styrene, double belt, pressureless continuous heating, and the like. A multilayer circuit board is manufactured by forming a circuit on the outermost metal foil layer of the laminated board which is not integrated by this molding.

Of course, it goes without saying that the details of the above manufacturing conditions and the like can be modified in various ways, including known ones.

(Function) In the manufacturing method of the present invention, by roughening the circuit surface of the inner layer material by cathodic treatment, the interlayer adhesion between the inner layer material and the prepreg layer is greatly improved, and excellent halo resistance is achieved. .

Hereinafter, the method of the present invention will be explained in more detail with reference to Examples.

(Example) Example 1 A circuit was formed on both sides of a double-sided copper-clad glass epoxy resin laminate having a thickness of 1FF111, and this was used as an inner layer material.

The circuit of this inner layer material is used as a cathode, @ 50 g / Jl
, using sulfuric acid 100f/, 11@electrolytic plating solution, 35
Two glass cloth epoxy resin prepregs each having a thickness of 0.0 and 0.1 mm were treated at a temperature of
Further, a copper foil having a thickness of 0.035++w+ was provided as the outermost layer.

This laminate was laminated and molded at a pressure of 401 qr/cll and a temperature of 165° C. for 60 minutes to obtain a four-layer circuit printed wiring board.

When this wiring board was evaluated for interlayer adhesion and halo resistance, the results shown in Table 1 were obtained. As is clear from the comparison with the comparative example described below, the interlayer adhesion was improved and the halo resistance was significantly improved.

Note that halo resistance was evaluated as liquid permeability associated with copper plating liquid treatment after through-hole drilling.

Examples 2 to 3 Wiring boards were manufactured in the same manner as in Example 1, with cathode treatment times of 1 minute and 8 minutes, and interlayer adhesion and halo resistance were evaluated. The results are shown in Table 1, and all had excellent properties.

Ratio example Without cathodic treatment shown in Example 1, NaCl0t
40t/, 11, NaOH15g/Jl, N
a s P O47t/J and Nai COs
It was immersed in an alkaline sodium chlorite aqueous solution of 'zr/1 at 90° C. for 7 minutes to perform a blackening treatment, and then a prepreg was provided in the same manner as in Example 1 to produce a 4-layer printed wiring board.

As shown in Table 1, interlayer adhesion and halo resistance were far inferior to Examples 1 to 3.

Table 1 (Effects of the invention) As explained in detail above, the production method of this invention
A multilayer printed wiring board with significantly improved interlayer adhesion and halo resistance is realized.

The reliability of a multilayer printed wiring board having a fine pattern circuit can be improved.

[Brief explanation of drawings]

FIG. 1 is a process sectional view illustrating the manufacturing method of the present invention. FIG. 2 is a process sectional view showing a conventional method. Engineering...Circuit 2...Inner layer material 3...Prepreg 4...Outer layer material

Claims (1)

[Claims] (1) A method for manufacturing a printed wiring board, which comprises roughening the circuits of the inner layer material by cathodic treatment, and then integrally molding a laminate in which the outer layer material is provided via a prepreg.