JPH0271586A - Manufacture of multilayer printed board - Google Patents

Abstract

PURPOSE:To remarkably decrease or eliminate halos or pink rings by treating the copper foil face of an inner layer board with an acid reductant water solution containing zinc formaldehydesulfoxylate after oxidizing chemically its copper foil face and forming a black or brown copper oxide face. CONSTITUTION:After polishing and washing the copper foil face of an inner layer board, pre-etching (soft-etching and chemical polishing) is performed with a water solution containing copper chloride or ammonium persulfate. After that, for example, its face is oxidized at a temperature of 70-100 deg.C with chemicals consisting of 15g/l of sodium hydroxide (NaOH), 31g/l of sodium hypochlorite (NaClO2), and 15g/l of sodium phosphate (Na3PH4) and then, a brown or black inner layer board is purified. Subsequently, it is treated with an acid reductant water solution containing zinc formaldehydesulfoxylate and then, the washed and dried inner layer board is obtained. Further, treatment with the acid reductant water solution is performed on condition that the concentration of zinc formaldehydesulfoxylate is 5-30g/l, pH is 0.1-7.0, a treatment temperature is 40-80 deg.C, and time of treatment is 0.5-5 minutes.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for manufacturing a multilayer printed wiring board, which is characterized by a method for treating a copper foil surface of a printed wiring board serving as an intermediate layer (inner layer). This method significantly reduces or eliminates the "halo" or "binkling" phenomenon caused by the copper oxide exposed on the hole wall being dissolved by the action of an acidic aqueous solution during the manufacturing process of multilayer printed wiring boards.

[Conventional technology and its problems]

In a multilayer printed board, a method of improving the multilayer adhesion of an inner layer board on which a printed wiring network is formed as an intermediate layer is to use a copper foil that has been textured on both sides in advance; After formation, there are two known methods: (1) forming a copper oxide film on the surface of the copper foil through chemical treatment; and (2) treating the copper foil surface with a silane coupling agent or an organic titanate coupling agent. Conventionally, from the viewpoint of adhesion and economy, after forming a printed wiring network for the inner layer on a copper-clad laminate with a glossy surface, it is treated with an oxidizing alkaline aqueous solution to form a brown or black copper oxide film. is used.

However, this copper oxide film, particularly cupric oxide, has the disadvantage that it easily dissolves in acidic aqueous solutions such as hydrochloric acid and sulfuric acid. For this reason, when making small holes in a laminated multilayer board and performing a through-hole plating process, electroless plating process, or subsequent electrolytic plating process, the copper oxide film exposed on the hole wall is dissolved by the acidic liquid. There is a drawback that "halo" or "binkling" occurs, which causes a decrease in the reliability of the printed wiring board, such as insulation properties.

As a method for preventing the halo or bink ring that occurs when this brown or black copper oxide film is used, a method of treating it with an alkaline reducing aqueous solution is known (Japanese Patent Laid-Open No. 153797/1983). . This method is
Although the adhesion strength is lower than that of brown or black copper oxide films, it exhibits an adhesion strength sufficient for practical use, but its effectiveness in preventing the occurrence of "halos" varies, and it has not yet been put into practical use.

[Means for Solving the Problems] The present inventors have conducted intensive studies on a method for reducing the brown or black copper oxide treatment so that the effect of preventing "halo" is uniform. As a result, we surprisingly discovered a method of using an acidic reducing agent aqueous solution containing a specific reducing agent instead of an alkaline reducing agent aqueous solution.

That is, in the method of manufacturing a multilayer printed wiring board, the present invention chemically oxidizes the copper foil surface of an inner layer board on which a printed wiring network used as an intermediate layer is formed to form a black or brown copper oxide surface, and then oxidizes the copper foil surface with zinc. treating the copper oxide surface with an acidic reducing agent aqueous solution containing formaldehyde sulfoxylate;
A method for producing a multilayer printed wiring board characterized by using an inner layer board formed by drying, and in particular, the acidic reducing agent aqueous solution has a concentration of zinc formaldehyde sulfoxylate l.
g/12~30g/CpH is 1.0 or more and less than 7.0, treatment temperature is 40~80℃, treatment time is 0.5~
This is a method for manufacturing a multilayer printed wiring board using conditions of 5 minutes.

The brown or black copper oxide film is formed from copper oxide mainly containing cupric oxide, and the above-mentioned "halo phenomenon" or "pink ring phenomenon" is caused by this cupric oxide cleaning through-holes and This occurs due to dissolution in acidic aqueous solutions used for through-hole plating, etc. In contrast, the present invention uses the same acidic aqueous solution as these treatment solutions to generate cuprous oxide, which is difficult to dissolve in the acidic aqueous solution, from a copper film mainly composed of cupric oxide. The treatment of the present invention eliminates the new problem of copper dissolution from brown or black copper oxide films, which are mainly made of cupric oxide, and significantly improves the ability to form halos or bink rings with adhesive strength that can be put to practical use. It was unexpected that this could be reduced or even eliminated.

The configuration of the present invention will be explained below.

The multilayer printed wiring board of the present invention is an inner layer board on which an inner layer printed wiring network used for the above-mentioned intermediate layer is formed, and after chemically oxidizing the copper foil surface to form a black or brown copper oxide surface, zinc The copper oxide surface is treated with an acidic reducing agent aqueous solution containing formaldehyde sulfoxylate and dried. In addition, the inner layer plate used for multilayer lamination molding, the prepreg used for multilayer adhesion, and the outer layer are used. Conventionally known materials and methods can be used, such as prepregs and laminated materials such as copper foil or single-sided copper-clad laminates, and laminated molding methods, and are not particularly limited.

Such laminated materials include E glass, S glass, D glass,
Various glass woven fabrics such as quartz glass, inorganic woven fabrics such as alumina paper; fully aromatic polyamide, polyimide, fluororesin, polyphenylene sulfide, polyetheretherketone, polyetherimide, and other super heat-resistant resins. Woven fabric: Woven fabric using composite yarn using the above-mentioned inorganic fibers and super heat-resistant resin fibers; Woven fabric such as a suitable combination of the above is used as a reinforcing base material, and bisphenol A type, novolac type Epoxy resins such as , halogenated bisphenol A type, halogenated novolak type, and other trifunctional or higher polyfunctional epoxy compounds; Typical examples include cyanato resin, cyanate ester-epoxy resin, cyanate ester-maleimide-epoxy resin, etc. cyanate ester resins; maleimide resins whose main components are polyfunctional maleimides such as bismaleimide and polyfunctional amines such as bis(4-aminophenyl)methane; Prepreg made of resin made from a composition of plastic resin and thermosetting resin, copper foil such as electrolytic copper foil or rolled copper foil, double-sided or single-sided copper cladding made by laminating and molding copper foil and prepreg. An example is a printed wiring board for inner layers (inner layer board) in which a printed wiring network for inner layers is formed on one or both sides of a laminate or a copper-clad laminate. In addition, as a lamination molding method, conventional hot platen press,
Examples include hot platen vacuum press and autoclave molding.

The method of forming a brown or black copper oxide film on the inner layer plate of the present invention is known. Usually, after polishing and cleaning the copper foil surface of the inner layer plate, pre-etching (softening) is performed with an aqueous solution such as copper chloride or ammonium persulfate. etching, chemical polishing)
After that, it is treated with an alkaline oxidizing aqueous solution. Here, the alkaline oxidizing aqueous solution and treatment conditions are specifically exemplified below, but are not limited thereto, and known methods can be used.

■ Sodium hydroxide (NaOll (15g/l)
) ) / Sodium hypochlorite (Na[:IL (31g
/It>)/sodium phosphate (15g/l, 7
0-100°C, 0.5-10 minutes.

■, Copper sulfate (50g/12)/sodium chloride (
200 g, 40-80°C, 3-15 minutes.

■, acetic acid (20 g/ammonium chloride (20 g/
l)/copper acetate (10g, #), 30-80℃, 1-1
0 minutes.

■, Copper acetate (10g/12) / Copper sulfate (24g/
l)/barium sulfide (24g/Il)/ammonium chloride (24g/(1), 40-50°C, 1-10
minutes.

■, Copper sulfate (25g/12) / Nickel sulfate (2
5g/l)/potassium chlorate (25g/j2), 70
~90°C, 1-10 minutes.

(2) Potassium persulfate (20 g/l)/sodium hydroxide 50 g/j'), 50-80°C, 1-3 minutes.

After cleaning the inner layer plate treated brown or black above,
Inner plates treated with an aqueous acidic reducing agent solution containing the zinc formaldehyde sulfoxylate of the present invention, washed with water, and dried are used in the present invention to significantly reduce or eliminate the occurrence of "halos".

Here, the acidic reducing agent aqueous solution containing zinc formaldehyde sulfoxylate of the present invention refers to zinc formaldehyde sulfoxylate (=ZnSO□・C
The concentration of H2O・211□0) is 5 to 30 g/(1, preferably 5 to 20 g#!), the pH is 1.0 or more and less than 7.0,
Preferably, the temperature is 2 to 4, the treatment temperature is 40 to 80°C, and the treatment time is 0.5 to 5 minutes.

In addition, pi is prepared by adding an organic acid such as formic acid or acetic acid, or an acid salt of copper formate or copper acetate, and the concentration in the case of an organic acid is exemplified in the range of 1 to 50 mf/g. .

Wash the treated inner layer board with water, air dry, and heat (especially at 80 to 20
The treated inner layer plate of the present invention is obtained by drying by a known method such as at 0° C.).

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 After removing about half of both sides of a double-sided copper-clad glass epoxy laminate with a thickness of 0.8 on and a copper foil thickness of 701 cm using a known etching method, Na0Il (15g/Il)/sodium hypochlorite (31g/( 1)/sodium phosphate (1)
After treating with an aqueous solution of 5g/j2) at 90°C for 5 minutes and washing with water, this inner layer plate was treated with zinc formaldehyde sulfoxylate (ZnSO□・CI+20-2112010g).
After treating with an aqueous solution of acetic acid/acetic acid (10 ml/A) at pH 3 to 4 at 80°C for 1.5 minutes, it was thoroughly washed with water and dried at 130°C for 30 minutes to obtain a treated inner layer plate.

3 sheets of glass epoxy prepreg (resin content 52%, thickness 0.1 mm) on both sides of the treated inner laminate, and a further thickness of 18 mm.
layered with electrolytic copper foil at a temperature of 175℃ and a pressure of 40kg/ct.
After laminating and forming a 4-layer plate for 2 hours at l, it was cooled and then laminated with a hole diameter of 0.4 mmφ, 80,000 r, p, m, 20 prisoners/
Under rotation conditions, holes were drilled at intervals of i, ooo, and 2.54 nno.

This perforated 4-layer board was immersed in a 4N llCl aqueous solution for 5 minutes to remove the halo around the hole in the inner layer at an arbitrary 1/2 inch of the total hole.
4 (125 pieces) were observed and the length of the largest one was measured.

Also, take the perforated four-layer board at 5CII+ corner and heat it at 100°C.
After boiling for 6 hours, a test was conducted by immersing it in solder at 260°C for 30 seconds.

In addition, in the above, using the 4N plate with holes drilled, after carrying out ordinary copper through-hole plating, the halo was similarly measured.

The results are shown in Table 1.

Example 2 In Example 1, zinc formaldehyde sulfoxylate (ZnS02.CH2[1.22
Table 1 shows the results obtained in the same manner except that an aqueous solution of H2O20#)/acetic acid (20 ml/n) was used.

Example 3 In Example 1, using the same reducing treatment liquid and setting the ratio of treatment area of the inner layer plate/treatment liquid volume to 0101 m''/11, the reduction treatment was performed 10 times without replenishing the reducing agent to the treatment liquid. The results of the 10th test are shown in Table 1.

Comparative Example 1.2 In Example 1, the black copper oxide treated inner layer plate was reduced using an alkaline reducing agent aqueous solution (30 wt% formalin aqueous solution 30 ml/l, K[]H 38 g, #, temperature 75°C).
) for 15 minutes in Comparative Example 1) and an alkaline reducing agent aqueous solution (sodium hypophosphite 30g/1, Na[]I).
I 5g/l, temperature 65°C) for 10 minutes (Comparative Example 2)
) The rest was the same. As a result, some say “hello”
There were some that were 0, but the largest ones were as shown in Table 1, and there was a large variation.

Example 4 In Example 1, a double-sided steel-clad glass-cyanate ester maleimide epoxy resin laminate (manufactured by Mitsubishi Gas Chemical, IIL 810) was used as the inner layer plate, and used as a prepreg for multilayer adhesive. Using glass cyanate ester-maleimide-epoxy resin prepreg (manufactured by Mitsubishi Gas Chemical q@, GIIPL 810), and using 1,4-dicyanatobenzene dissolved as a dilute solution of cyanato compound for surface treatment, multilayer laminate molding was performed. Conditions: Temperature 2
The results are shown in Table 2 under the same conditions except that the temperature was changed to 00°C for 2 hours.

It allows multilayer printed wiring boards to be manufactured with high productivity, and has extremely high industrial significance.

Patent applicant Mitsubishi Gas Chemical Co., Ltd. Agent Patent attorney (9070) Sadafumi Kobori [Operation and effects of the invention]

Claims (1)

[Claims] 1. In a method for manufacturing a multilayer printed wiring board, after chemically oxidizing the copper foil surface of an inner layer board on which a printed wiring network used as an intermediate layer is formed to form a brown or black copper oxide surface,
A method for manufacturing a multilayer printed wiring board, comprising treating the copper oxide surface with an aqueous acidic reducing agent solution containing zinc formaldehyde sulfoxylate and drying the inner layer board. 2 The acidic reducing agent aqueous solution has a zinc formaldehyde sulfoxylate concentration of 5 g/l to 30 g/l and a pH of 1.
．． 0 or more and less than 7.0, and the processing temperature is 40 to 80°C,
The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the processing time is 0.5 to 5 minutes.