JPH02129996A - Manufacturing method of multilayer printed board - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 "pink ring" 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 "pink ring" 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 pink 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 Application Laid-Open No. 153797/1982). . 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 to solve the problem]

The inventors of the present invention have conducted intensive studies on methods for reducing the brown or black copper oxide treatment to ensure that the effect of preventing "halo" is consistent. As a result, we surprisingly discovered a method using a specific reducing agent and an acidic reducing agent aqueous solution containing a copper salt in place of an alkaline reducing agent aqueous solution.

That is, in the method of manufacturing a multilayer printed wiring board, the present invention involves 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 black or brown copper oxide surface, and then performing the following steps. reducing agent, which is sodium phosphite;
A multilayer printed wiring characterized by using an inner layer plate obtained by treating the copper oxide surface with an acidic reducing agent aqueous solution containing a copper salt of an organic or inorganic acid and, if necessary, an acid for pH adjustment, and drying the surface. This is a method for manufacturing a board, and the acidic reducing agent aqueous solution has a concentration of sodium hypophosphite of 5 g/12 to 3
00g/l, the concentration of copper salt is 0.1-200g/12.
The pH is 1.0 or more and less than 7.0, and the treatment temperature is 40
This is a method for manufacturing a multilayer printed wiring board, characterized in that the temperature is 80° C. and the processing time is 0.5 to 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. By the treatment of the present invention, there is no new problem of copper dissolution from brown or black copper oxide films, which are mainly made of cupric oxide, and halos or pink rings with adhesion strength that can be put to practical use can be significantly improved. 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, In addition to treating the copper oxide surface with an acidic reducing agent aqueous solution containing sodium phosphite and drying it, it is also used as an inner layer plate for multilayer lamination molding and for multilayer adhesion. Conventionally known materials and methods can be used, including prepregs for forming the outer layer, laminate materials such as copper foil or single-sided copper-clad laminates, and laminate 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 (NaOH (15g/ll))
/ Sodium hypochlorite (NaC10□ (31g/β)
) / Sodium phosphate (15g #, 70-100℃
, for 0.5-10 minutes.

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

■, acetic acid (20g/l)/ammonium chloride (20g/l)
j2)/copper acetate (10g/j2), 30-80℃
, for 1-10 minutes.

■, Copper acetate (10g/I!) / Copper sulfate (24g/
(!) /Barium sulfide (24g/12)/Ammonium chloride (24g/ (1), 40-50℃, 1-1
0 minutes.

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

(2) Potassium persulfate (20g/(Li/50g of sodium hydroxide #2), 50-80°C, 1-3 minutes.

After cleaning the inner layer plate treated brown or black above,
The inner layer plate of the present invention is treated with an aqueous acidic reducing agent solution containing hypophosphorous acid (IJ), a copper salt of an organic acid or an inorganic acid, and an acid for pH adjustment as necessary, washed with water, and dried. This greatly reduces or eliminates the occurrence of "halos".

The acidic reducing agent aqueous solution of the present invention means that the concentration of sodium hypophosphite ("Na82PO2), which is a reducing agent, is 5 to 3°O.
g/j', preferably L<Lt 10-100g/12
, the concentration of copper salt of organic acid or inorganic acid is 0.1-200g
/ 12, preferably 1-50g #2 SpH is 1.
0 or more and less than 7.0, preferably 2.0 to 5.0,
The conditions used are a treatment temperature of 40 to 80°C and a treatment time of 0.5 to 5 minutes.

Examples of copper salts of organic acids or inorganic acids include copper salts of inorganic acids such as steel chloride and copper sulfate, and copper salts of organic acids such as copper formate and copper acetate. In addition, as an acid to be used as necessary,
Examples include organic acids such as formic acid and acetic acid, with concentrations ranging from 1 to
50rrL1. A range of ll is exemplified.

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 Thickness: 0.8 mm, copper foil thickness: 70. After removing about half of both sides of the double-sided copper-clad glass epoxy laminate using a known etching method, NaOH (15g/(1)/hypochlorous acid) was added.
IJium (31g#)/Sodium Phosphate (15g#)
After treating with an aqueous solution of Na82PO2 at 90℃ for 5 minutes and washing with water, the inner layer plate was treated with sodium hypophosphite (Na82PO230g).
/ (1) / Copper sulfate (30 g / Acetic acid (3 m1. /
l) using an acidic reduction treatment aqueous solution with a pH of 3.0 to 4.0, treated at 80 t for 1.5 minutes, and then thoroughly washed with water.
A treated inner laminate was obtained by drying at 130 tons for 30 minutes.

Three sheets of glass epoxy prepreg (resin content 52%, thickness 0.1 mm) and 18 mm thick electrolytic copper foil were layered on both sides of the treated inner laminate at a temperature of 175°C and a pressure of 40 kg/cm.
After laminating and forming a 4-layer plate at f for 2 hours, it was cooled, and then it was molded with i, ooo holes at a spacing of 2.54 mm under the conditions of a hole diameter of 0.4 Mφ, 80,000 r, p, mo, and 20 n/rotation. It was open. Note that the treated copper foil surface of the inner layer with holes was black.

This perforated 4-layer plate was immersed in a 4N IIcI 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 a 5 cm square piece of the 4-layer board with holes and heat it at 100°C for 6
After boiling for an hour, a test was conducted by immersing it in solder at 260°C for 30 seconds.

Further, in the above, using the perforated four-layer board, 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, the acidic reduction treatment aqueous solution was sodium hypophosphite (NaH2PO□50g/l)/copper sulfate (30g/l)/acetic acid (4mjl!#) at pH 3.0~
Table 1 shows the results obtained in the same manner except that a 4°0 aqueous solution was used.

Example 3 In Example 1, the same acidic reduction treatment aqueous solution was used, and the ratio of treatment area of inner layer plate/treatment liquid volume was 0.01 m'/1.
(1) The reduction treatment was performed 20 times without replenishing the reducing agent to the treatment solution, and the results of the 20th treatment are shown in Table 4.

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% by weight formalin aqueous solution 30ml/l, KO838g#!, temperature 75°C)
) for 15 minutes (Comparative Example 1) and an alkaline reducing agent aqueous solution (sodium hypophosphite 30g/1, Na0II
5g/l, temperature 65°C) for 10 minutes (Comparative Example 2)
The rest was the same. As a result, some people say “Hello” 0
Although there were some cases, the largest one was as shown in Table 1, and there was a large variation.

Example 4 In Example 1, a double-sided copper-clad glass-cyanate ester maleimide epoxy resin laminate (manufactured by Mitsubishi Gas Chemical Co., Ltd., L ratio 810) was used as the inner layer plate, and a prepreg for multilayer adhesive was used. As glass cyanate ester-
Maleimide-epoxy resin prepreg (Mitsubishi Gas Chemical ■
GHPL 810), a dilute solution of cyanato compound for surface treatment in which 1,4-dicyanatobenzene was dissolved, and the multilayer lamination molding conditions were a temperature of 200°C,
Table 2 shows the results in the same manner except that the time was changed to 2 hours.

In the through-hole plating process that creates electrical continuity between wiring, the occurrence of "halos" that tend to cause defects such as electrical short circuits due to the dissolution of brown or black copper oxide in the plating solution is greatly reduced, or The process time is significantly shortened compared to conventional alkaline reducing agent aqueous solution treatment, and it can be used repeatedly, making it possible to manufacture highly reliable multilayer printed wiring boards with high productivity, making it an industrial option. The significance of this is extremely high.

Patent Applicant Mitsubishi Gas Chemical Co., Ltd. Agent Patent Attorney (9070) Sadafumi Tebori [Operations 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,
An inner layer plate obtained by treating the copper oxide surface with an acidic reducing agent aqueous solution containing a reducing agent such as sodium hypophosphite, a copper salt of an organic acid or an inorganic acid, and an acid for pH adjustment as necessary, and drying. A method for manufacturing a multilayer printed wiring board characterized by using. 2 The acidic reducing agent aqueous solution has a sodium hypophosphite concentration of 5 g/l to 300 g/l and a copper salt concentration of 0.1 to 20 g/l.
The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the pH is 1.0 or more and less than 7.0, the treatment temperature is 40 to 80°C, and the treatment time is 0.5 to 5 minutes.