JPH02250395A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To improve layer adhesion by forming a lamination body integrally which is provided with an outer layer material through a prepreg by heating and pressurizing after forming a resin layer on a surface of an inner layer material by fluid immersion method. CONSTITUTION:After a resin layer 3 is formed on a surface of an inner layer material 2 by fluid immersion method, a lamination body which is provided with an outer layer material 5 through a prepreg 4 is integrally formed by heating and pressurizing. In the fluid immersion method, powder resin of about 4 to 50mum is made to stray uniformly by air which is sprayed upward inside a fluid bath to kept the resin floating, and a board is immersed in the fluid bath to dissolve and attach the resin thereto. Thereby, it is possible to form a resin layer uniformly and effectively and to improve layer adhesion between an inner layer material and a prepreg layer greatly.

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 improves the adhesiveness between an inner layer material and a prepreg layer and improves the reliability of a multilayer wiring board having a fine pattern circuit.

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

Conventionally, for printed wiring boards having such a multilayer structure, for example, as shown in Figure 2, a circuit (A) formed on the copper foil surface of a single-sided or double-sided copper-clad laminate is used as an inner layer material (B). Then, the surface of this inner layer material (a) is roughened, or after this roughening, it is treated with an alkaline sodium chlorite aqueous solution, etc. to form a black copper oxide film on the surface of the copper foil circuit (a). After that, one side w48 through the prepreg layer(s)! It has been manufactured by disposing a laminate plate or #A foil (work) as an outer layer material and integrally molding it.

(Problem B to be solved by the invention) Although the conventional manufacturing method described above can secure reliability for circuits with conventional pattern densities, in recent years, circuit densities have increased significantly, and fine pattern In circuits, 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. The contact area between the resin layer and the prepreg layer (1) decreases, and even if the copper foil circuit (A) is surface-treated,
This is due to the unavoidable decrease in interlayer adhesion at this contact surface.

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

(Means for Solving the Problems) This invention solves the above problems by forming a resin layer on the surface of an inner layer material by a fluidized dipping method, and then disposing an outer layer material on the outermost layer via a prepreg. Provided is a method for manufacturing a printed wiring board, characterized in that the body is integrated by heating and pressure molding.

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

(a) A resin layer (3) is formed by a fluidized dipping method on the surface of an inner layer material (2) formed from prepreg and metal foil such as copper foil and having a circuit (1) on one or both sides.

In this case, the fluidized immersion method generally involves suspending powdered resin with a size of about 4 to 50 μm in a fluidized tank using air blown upward to keep it in a fluidized state. In this method, the substrate is immersed in water to melt and adhere the resin. This coating method enables uniform coating and is known as a simple and efficient coating method. Utilizing this method, in the present invention, the inner layer material (2) is immersed in a resin fluidized tank to form a resin layer (3) on its surface.

As the resin at this time, epoxy resin, phenol resin, etc. can be suitably used. The coating thickness of the resin layer (3) is preferably about 10 to 100 microns.

In addition, when implementing the fluidized immersion method, metal powder that enters from the equipment during the production of powdered resin, etc.
In order to remove this metal powder, it is preferable to drive a magnetic belt vertically and horizontally in the fluidized tank to remove the floating magnetic powder.

(b) Inner layer material (2) on which resin layer (3) was then formed
A required number of prepregs (4) and outer layer materials (5) are disposed and laminated and fixed together by heat and pressure.

Prepreg (4) is preferably arranged, for example, about 1 to 3 sheets, but is not limited to this. As prepreg (4), cloth such as glass cloth, aramid cloth, polyester cloth, or mat-like cloth can be used. A material obtained by impregnating a resin such as an epoxy resin or a polyimide resin into a base material such as a material or a base material such as a nonwoven fabric or paper can be used. Among these, glass cloth epoxy resin prepreg is exemplified as a suitable one.

As the outer layer material (5), a metal foil such as copper, aluminum, or stainless steel, or a single-sided metal-clad laminate made of prepreg and these metal foils can be used.

Among these, those using silver foil as the outer layer/material (5) are preferred.

The heat and pressure molding can be carried out as appropriate according to conventionally known methods and conditions. A multilayer circuit board is manufactured by forming a circuit on the outermost metal foil layer of the laminated board integrated by this molding.

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

(Function) In the manufacturing method of the present invention, a resin layer is simply, uniformly, and efficiently formed on the surface of the inner layer material by a fluidized dipping method, and the interlayer adhesion between the inner layer material and the prepreg layer is greatly improved. It can achieve excellent halo resistance.

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

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

This inner layer material was immersed in a powdered epoxy resin fluid in an upwardly opening box type fluidized tank, and an epoxy resin layer with a thickness of 5 microns was formed on the surface.4 Next, a glass cloth epoxy resin prepreg with a thickness of 0.11 nI was formed. Two sheets of each are placed on both sides, and a 0.035-thick copper foil is placed on the outermost layer.

This laminate was laminated and molded at a pressure of 40 kg/- 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 property, the results shown in Table 1 were obtained. Adhesion has improved and halo properties have been significantly reduced.

In addition, the halo property was evaluated as the liquid permeability associated with plating liquid treatment after drilling.

Examples 2 to 4 The thickness of the resin layer was 30 microns, 70 microns, and 80 microns.
A wiring board was manufactured using Micron in the same manner as in Example 1, and the glabella adhesiveness and halo property were evaluated. The results are also shown in Table 1, and both had excellent properties.

Comparative Example Without forming the resin layer shown in Example 1, the inner layer material was
After immediately immersing it in an alkaline sodium chlorite aqueous solution for 3 minutes to perform a blackening treatment, a four-layer printed wiring board was produced in the same manner as in Example 1.

As shown in Table 1, glabellar adhesion and halo resistance were far inferior to Examples 1 to 4.

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

Multilayer printed wiring board with fine pattern circuit (
811 characteristics 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. 1...Circuit 2...Inner layer material 3...Resin layer 4...Prepreg 5...Outer layer material

Claims (1)

[Claims] (1) A printed wiring board characterized in that a resin layer is formed on the surface of the inner layer material by a fluidized dipping method, and then the outermost outer layer material is disposed via a prepreg, and the laminate is integrally formed by heating and pressure molding. manufacturing method.