JPH08204336A - Manufacture of board for multilayer printed circuit board - Google Patents

Abstract

PURPOSE: To provide a board for a multilayer printed wiring board in which harrowing of the periphery of a through hole-plating can be suppressed, an interlayer peeling is entirely eliminated and an external appearance inspection is facilitated by obtaining an adhesive force of a copper foil circuit pattern to prepreg resin. CONSTITUTION: A method for manufacturing a multilayer printed wiring board has the steps of disposing to superpose one or more inner layer printed circuit boards via a prepreg on at least one surface of an outer layer board or a copper foil, heating, pressurizing and integrally laminating it, and comprises the steps of etching the surface of the copper foil circuit pattern of the inner layer printed circuit board with air oxidation by organic acid soft etchant containing no hydrogen peroxide as the inner layer printed circuit board to form a roughed surface, and then generating black oxide film on the roughed surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a substrate for a multilayer printed wiring board, and more particularly to treatment of a copper foil circuit pattern surface of an inner layer printed circuit board.

[0002]

2. Description of the Related Art Generally, a substrate for a multilayer printed wiring board is manufactured by the following procedure. First, a single-sided or double-sided copper clad laminate is used as a starting material to form a copper foil circuit pattern on a copper foil on one side or both sides of this laminate by a printing method to obtain an inner layer printed circuit board, and then both sides of this inner layer printed circuit. Alternatively, a prepreg is superposed on one side, an outer layer copper foil is further superposed on the prepreg, and the whole is heated and pressed to be integrated to obtain a multilayer printed wiring board substrate. The inner layer printed circuit board used for the multilayer printed wiring board substrate is a single-sided or double-sided copper-clad laminate as a starting material as described above, and the circuit pattern is printed on the surface copper foil. Has a silky surface, and at least one such inner layer printed circuit board is placed on at least one surface of the prepreg via a prepreg, and the prepreg is used for lamination and integration. Since the adhesive strength with the resin is insufficient, a layer of copper oxide is formed on the surface of the copper foil circuit pattern to increase the adhesive area as the surface of the unevenness caused by the copper oxide, and to improve the adhesive strength due to the anchor effect. Measures to improve have been adopted.

The copper oxide layer can be formed, for example, by immersing it in an oxidizing treatment solution shown below. Caustic soda 5-100g / l, Sodium chlorite 30
~ 300 g / l, zinc phosphate 0.1-10 g / l, trisodium phosphate 0-20 g / l in an aqueous solution containing components,
Immerse at a temperature of 40 to 100 ° C. for 10 seconds to 10 minutes. Alkaline sodium chlorite aqueous solution (sodium chlorite 50-150 g / l, sodium hydroxide 10-
50 g / l, trisodium phosphate 1-20 g / l, temperature 80-100 ° C.) for 2-5 minutes. Alkaline potassium persulfate aqueous solution (potassium persulfate 10 g / l, sodium hydroxide 50 g / l, temperature 80-
Immerse in 100 degreeC for 2 to 5 minutes. Barium sulfide 24g / l, ammonium chloride 24g
/ L, copper acetate 30g / l, copper sulfate 24g / l, temperature 40
Dip in (~ 50 degreeC) for 2 to 5 minutes.

The copper oxide layer thus obtained can be improved in terms of adhesive strength, and when the copper oxide layer exhibits a black color, it is laminated and formed on a substrate for a multilayer printed wiring board. However, since the copper oxide formed on the surface of the circuit pattern copper foil easily dissolves in acid, the multilayer printed wiring board substrate is printed The copper oxide layer formed on the surface of the copper foil circuit pattern is eroded by acids such as hydrochloric acid and sulfuric acid used in the through-hole plating process that passes through when finishing a wiring board, and the copper oxide brown or black to copper pink A phenomenon (haloing) that causes colored erosion marks occurs, and the adhesive strength of that part decreases, so that the interlayer peels due to thermal shock during the soldering process of the multilayer printed wiring board, There is a problem that there can lead to accidents bets wiring board.

The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain an adhesive force between a copper foil circuit pattern and a prepreg resin and suppress haloing around through-hole plating. An object of the present invention is to provide a substrate for a multilayer printed wiring board which is capable of being free from delamination and which can be easily inspected for appearance.

[0006]

In order to solve the above-mentioned problems, the present invention does not contain hydrogen peroxide on the surface of a copper foil circuit pattern as an inner layer printed circuit board used for a multilayer printed wiring board substrate. The organic acid-based soft etching agent was used to form a roughened surface by etching while being accompanied by air oxidation and then to use a black oxide film formed on the roughened surface. In the present invention, the etching for forming the roughened surface on the copper foil circuit pattern surface of the printed circuit board for the inner layer is carried out by air-oxidation with an organic oxygen-based soft etching agent containing no hydrogen peroxide. The etching depth is preferably about 0.3 to 5.0 μm. If the etching depth is 0.3 μm or less, the unevenness of the surface is small and there is no effect in improving the adhesive strength.
If the thickness is 5.0 μm or more, a large adhesive force can be obtained, but the required thickness of the copper foil circuit pattern cannot be secured. As the etching agent that can be used in the present invention, the one commercially available under the trade name of CZ-5450 from Mech Co., Ltd. can be used. The black oxide film formed on the roughened surface is not particularly limited, and for example,
Caustic soda 5-10 shown in paragraph 0003 above
0 g / l, sodium chlorite 30-300 g / l, zinc phosphate 0.1-10 g / l, trisodium phosphate 0-20
A liquid temperature of 40 to 100 ° C. in an aqueous solution containing g / l of component,
It can be generated by dipping under the condition of dipping time of 10 seconds to 10 minutes.

[0007]

Example 1 First, a double-sided printed circuit board for inner layer was prepared, and this inner layer printed circuit was degreased with a degreasing solution (Metex S-1).
707: Nihon MacDamid Co., Ltd.) It was immersed in 65 ° C. for 5 minutes and then washed with water. Then, a hydrogen peroxide-free organic acid-based soft etching solution (CZ-5450: manufactured by Mec Co., Ltd.) is sprayed at a liquid temperature of 35 ° C. for 60 seconds, and etching is performed while air oxidation is performed to form a roughened surface. Formed and then washed with water. Then, the following (a), (b), (c),
A black copper oxide film is formed on the roughened surface by immersing it in the oxidizing treatment aqueous solution of the component (d) at 60 ° C. for 2 minutes, and then washing with water.
It was dried at 5 ° C. for 40 minutes. -Note- (a) Caustic soda ... 10 g / l (b) Sodium chlorite ... 100 g / l (c) Zinc phosphate ... 0.5 g / l (d) Trisodium phosphate ... 5 g / l This black copper oxide film 4 layers printed by stacking prepregs on the upper and lower surfaces of the double-sided printed circuit board for the inner layer, and further stacking copper foil for the outer layer on the upper and lower surfaces of the prepreg, and heating and pressing from the top and bottom to integrate them. A wiring board substrate was obtained.

[0008]

Example 2 A four-layer printed wiring board substrate was obtained in the same manner as in Example 1 except that the spray time of the organic acid-based soft etching solution in Example 1 was changed to 30 seconds.

[0009]

Comparative Example 1 A substrate for a four-layer printed wiring board was obtained in the same manner as in Example 1 except that the spray time of the organic acid-based soft etching solution in Example 1 was changed to 5 seconds.

[0010]

Comparative Example 2 A 4-layer printed wiring board substrate was obtained in the same manner as in Example 1 except that the soft etchant of Example 1 was changed to sulfuric acid-hydrogen peroxide system and immersed for 60 seconds.

[0011]

Comparative Example 3 A four-layer printed wiring board substrate was obtained in the same manner as in Example 1 except that the soft etchant of Example 1 was changed to sulfuric acid-persulfate system and immersed for 60 seconds. Through holes of 0.4 mmφ were formed at predetermined positions on the four-layer printed wiring board substrates of Examples 1 and 2 and Comparative Examples 1, 2, and 3, and the through holes were plated by a conventional method. Halo value, solder heat resistance, inner layer peel strength,
The appearance inspectability was measured, and the results are shown in Table 1.

[0009]

Although the above-mentioned Examples and Comparative Examples have been described by taking the substrate for a four-layer printed wiring board as an example, it goes without saying that the same applies to the case of a higher multilayer.

[0011]

EFFECT OF THE INVENTION The present invention provides a multilayer printed wiring board which has excellent appearance inspectability because the inner layer circuit copper has a black appearance color, does not increase the haloing amount, has a high inner layer peel strength, and has excellent solder heat resistance. There is an effect that a substrate for use can be provided.

Claims (1)

[Claims] 1. A multilayer printed wiring board in which at least one printed circuit board for an inner layer is placed on at least one surface of a substrate for an outer layer or a copper foil with a prepreg interposed therebetween, and the layers are laminated by heating and pressing. A method for manufacturing a substrate for use as an inner layer printed circuit board, comprising: etching the copper foil circuit pattern surface of the inner layer printed circuit board with an organic acid-based soft etching agent containing no hydrogen peroxide while accompanied by air oxidation. A method of manufacturing a substrate for a multilayer printed wiring board, comprising forming a roughened surface and then forming a black oxide film on the roughened surface.