JP2002057457A - Manufacturing method of multilayered printed-wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered printed-wiring board that has superior solder heat resistance and inner layer peel strength by carrying out internal layer copper foil treatment having an improved boding property with resin, and by increasing adhesion force between internal layer copper foil and resin. SOLUTION: A specific number of prepregs, where a thermosetting resin is impregnated to glass cloth are overlapped, a circuit is formed on an internal layer plate integrated by overlapping copper foil to the outside, and the prepregs are overlapped to the outside of the internal layer plate for integration, thus manufacturing a multilayered board. In this case, to improve the adhesion strength between the copper foil and resin, the internal layer copper foil, where the circuit is formed is treated by etching treatment liquid containing sulphuric acid, hydrogen peroxide water, and a corrosion prevention agent, or that containing the sulphuric acid, hydrogen peroxide water, corrosion preventing agent, and a water-soluble polymer, and is treated by an alkaline solution furthermore, thus integrating the multilayered board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a multilayer printed wiring board having excellent solder heat resistance, inner layer peeling strength and acid resistance.

[0002]

2. Description of the Related Art In recent years, high-speed, high-integration LSIs, large-capacity memories, and small, lightweight, and thin electronic parts have been rapidly advanced. In addition, the demand for environmentally friendly substrate materials has been increasing worldwide, and the use of halogen-free, antimony-free, and lead-free solder on substrates has been expanding.

Accordingly, the solder bath temperature during reflow is
It is on the rise. For this reason, the thermal problem of the substrate has become a major issue, and the solder heat resistance of the substrate
An improvement in the inner layer peeling strength is required.

Conventionally, a multilayer board has been subjected to a surface treatment called blackening treatment in order to improve the adhesion of the surface of the inner copper foil. This is because after performing a predetermined circuit formation on the inner layer board,
This is a method of manufacturing a multilayer board by treating the surface of a copper foil with a treatment solution such as sodium chlorite, sodium hydroxide, sodium phosphate, etc., forming a copper oxide film, and then laminating and molding through a prepreg.

[0005]

However, in the conventional blackening-processed multilayer board, the copper oxide film is dissolved by the treatment with an acidic pretreatment solution or a plating solution in a through-hole plating process after drilling, and the pink ring is formed. The phenomenon called was occurring. The occurrence of the pink ring causes a problem that the connection reliability and the heat resistance of the multilayer board are reduced, and many improvement methods have been proposed as countermeasures.

For example, a method of treating a copper foil with an aqueous solution containing an oxidizing agent to form a copper oxide film, and then bringing the copper oxide film into contact with an aqueous solution containing a formaldehyde supply source to reduce the copper oxide film to improve acid resistance (Japanese Patent Application Laid-Open No. H10-163,837) 62-185888). However, a part of the copper oxide is not entirely reduced to copper metal, but is reduced to copper hydroxide, heat resistance is not improved, and management of the processing solution is complicated.
In contrast, according to the method of treating the copper foil surface using the hydrogen peroxide-containing aqueous composition, the copper foil surface is finely roughened, has excellent acid resistance, and has a thermally stable treated surface. It was found to be obtained (Japanese Patent Application No. 10-161632). However, in this method, there was a problem that the adhesion to the inner layer copper foil was poor.

[0007] It is an object of the present invention to provide an inner layer copper foil having excellent adhesiveness to a resin, to improve the adhesion between the inner layer copper foil and the resin, and to provide a multilayer print excellent in solder heat resistance and inner layer peeling strength. It is intended to provide a wiring board.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, as a method of improving the adhesion between the inner layer copper foil and the resin, sulfuric acid was added to the inner layer copper foil. After the treatment with an etching solution containing hydrogen oxide and a corrosion inhibitor, by further performing an alkali solution treatment, it is possible to improve the adhesion between the inner layer copper foil and the resin, and it has been found that the above object can be achieved. It has been completed.

That is, according to the present invention, a predetermined number of prepregs obtained by impregnating a glass cloth with a thermosetting resin are stacked,
After forming a circuit on the inner layer plate which is formed by laminating copper foil on the outside, the prepreg is further laminated on the outside of the inner layer plate to form a multilayer board. For improvement, the inner layer copper foil on which the circuit was formed was treated with an etching solution containing sulfuric acid, hydrogen peroxide and a corrosion inhibitor, or an etching solution containing sulfuric acid, hydrogen peroxide, a corrosion inhibitor and a water-soluble polymer. A method for producing a multilayer printed wiring board, comprising treating the substrate, further treating the substrate with an alkaline solution, and then integrally forming the multilayer board.

Hereinafter, the present invention will be described in detail.

In the case where the present invention is applied, the raw materials of the prepreg and copper foil, the kind of the inner layer plate as the core, the laminated structure such as the pin laminating method, the mass laminating method and the sequential method, and the pressing conditions are particularly restricted. Absent.

The inner layer plate on which the circuit is formed is immersed in a solution containing sulfuric acid, hydrogen peroxide and a corrosion inhibitor as main components, and irregularities are formed on the surface of the inner layer copper foil by etching. At this time, the surface of the copper foil is simultaneously coated with a corrosion inhibitor so that rust does not occur after the treatment. This is because the surface of the copper foil is formed asperities by etching with a treatment solution containing sulfuric acid, hydrogen peroxide, and a corrosion inhibitor, and at the same time, a rust preventive film is formed on the asperities. Further, the rust preventive film on the unevenness is further strengthened by the addition of a water-soluble polymer to the etching treatment liquid containing sulfuric acid, hydrogen peroxide and a corrosion inhibitor as main components.

As the corrosion inhibitor for the etching agent used in the present invention, those based on triazoles such as benzotriazole and those based on imidazole are particularly suitable. As the water-soluble polymer, an ethylene oxide polymer (polyethylene glycol), polyvinyl alcohol and the like are preferable. The etching solution is mixed with an aqueous solution of concentrated sulfuric acid 70 to 110% by weight, 50% hydrogen peroxide solution 12 to 30% by weight, corrosion inhibitor 6 to 12 g / l, and water-soluble polymer 3 to 6 g / l. Is preferred.

The thickness of the rust-preventive film is as thin as several angstroms, so that the uneven surface formed on the copper foil surface and improving the adhesion between the inner copper foil and the resin is prevented from rusting. Maintains heat resistance.

However, an organic film having a corrosion inhibitor and a rust-preventing effect has a drawback that the adhesion between the inner copper foil and the resin is reduced.

To solve this problem, it is possible to reduce the thickness of the rust preventive layer by reducing the content of the corrosion inhibitor in the processing solution. Not only is difficult to control, but also takes time to process, which leads to a decrease in productivity. In addition, if the anti-corrosion film or organic film layer formed first is made thinner, the adhesion between the inner copper foil and the resin is improved, but if the storage time after treatment is long, the inner copper foil will rust. there were.

According to the present invention, there is provided a rust-preventive layer on the uneven surface of the inner copper foil,
After forming the organic film layer, the film thickness is reduced to an appropriate thickness with an alkali solution to improve the adhesion between the inner copper foil and the resin without impairing the rust prevention effect.

The solution for thinning the rust preventive layer and the organic coating layer can be used without any particular limitation as long as it is an alkaline type, but sodium hydroxide is inexpensive and easy to handle. The concentration of the aqueous sodium hydroxide solution is in the range of 0.5 to 2.0 N, and the immersion temperature and time may be determined by experiments.

[0019]

According to the present invention, the adhesion between the copper foil and the resin is further improved by performing an alkali solution treatment after the etching treatment with a treatment solution containing sulfuric acid, hydrogen peroxide and a corrosion inhibitor as a method of improving heat resistance. Characterized by the fact that
Thereby, a multilayer printed wiring board having excellent solder heat resistance, inner layer peeling strength, and the like can be manufactured.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described specifically with reference to embodiments. The present invention is not limited by these examples. In the following Examples and Comparative Examples, “parts” means “parts by weight”.

Example 1 A glass cloth having a thickness of 180 μm was coated with 90 parts of a brominated epoxy resin (epoxy equivalent: 480), 7 parts of a cresol novolak resin (epoxy equivalent: 210), and dicyandiamide 3
Part, a resin solution having a viscosity of 1.5 poise prepared by adding 2-ethyl-4-methylimidazole as an accelerator and methyl cellosolve as a diluting solvent was applied and dried to obtain a resin component 4.
3% prepreg was obtained. 6 prepregs and thickness 3
A 5 μm copper foil was overlaid and heated and pressed, and a circuit was formed on the obtained inner layer material. Next, sulfuric acid (4.0% by weight), hydrogen peroxide (5.0% by weight), triazole (5.0 g / l) as a corrosion inhibitor, and ethylene oxide polymer (5 g / l) as a water-soluble polymer were used. Etching was performed at 40 ° C. for 1 minute with the treatment liquid containing the solution, and the substrate was further immersed in a 0.9N sodium hydroxide solution for 1 minute. Thereafter, drying was performed at 90 ° C. for 5 minutes. Furthermore, a prepreg similar to that used for the inner layer material was laminated on both sides one by one, and a copper foil having a thickness of 18 μm was laminated on both sides and heated and pressed to form a multilayer copper-clad laminate having a thickness of 1.6 mm. Manufactured.

Example 2 The same inner layer material as used in Example 1 was treated with sulfuric acid (4.
0% by weight), hydrogen peroxide (5.0% by weight), and a treatment solution containing triazole (5.0 g / l) as a corrosion inhibitor at 40 ° C. for 2 minutes, followed by 0.9N sodium hydroxide. Dipped in the solution for 1 minute. Then 90
Drying was performed at 5 ° C. for 5 minutes. Furthermore, a prepreg similar to that used for the inner layer material was laminated on both sides one by one, and a copper foil having a thickness of 18 μm was laminated on both sides and heated and pressed to form a multilayer copper-clad laminate having a thickness of 1.6 mm. Manufactured.

Example 3 An inner layer material was treated in the same manner as in Example 2, except that a 0.9N potassium hydroxide solution was used instead of the 0.9N sodium hydroxide solution.
Further, in the same manner as in Example 2, a multilayer copper-clad laminate having a thickness of 1.6 mm was manufactured.

COMPARATIVE EXAMPLE 1 The same inner layer material as used in Example 1 was treated with sulfuric acid (4.0
%), Hydrogen peroxide (5.0% by weight), and a treatment solution containing triazole (5.0 g / l) as a corrosion inhibitor, and dried at 90 ° C. for 5 minutes after the treatment. Furthermore, a prepreg similar to that used for the inner layer material was laminated on both sides one by one, and a copper foil having a thickness of 18 μm was laminated on both sides and heated and pressed to form a multilayer copper-clad laminate having a thickness of 1.6 mm. Manufactured.

Comparative Example 2 The inner layer material was treated in the same manner as in Comparative Example 1, except that the amount of the corrosion inhibitor used as the treatment solution was halved to 2.5 g / l. Further, a thickness of 1.6 was obtained in the same manner as in Comparative Example 1.
mm multilayer copper-clad laminates were produced.

The copper-clad laminates obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were tested for solder heat resistance, inner layer peeling strength, and rust resistance. The results are shown in Table 1.
In each case, the present invention was excellent, and the effects of the present invention could be confirmed.

[0027]

[Table 1] * 1: Floating in a solder bath at 260 ° C. for 30 seconds, and occurrence of blister was observed.

* 2: The release film was inserted between the inner layer plate and the outer layer prepreg during molding, and the inner layer peeling strength was measured according to JIS-C-6481 after molding.

* 3: After being treated with a 10% hydrochloric acid solution, it was left for 1 hour, and the discoloration of the copper foil surface was observed.

[0030]

As apparent from the above description and Table 1, according to the present invention, it is possible to manufacture a multilayer printed wiring board having excellent solder heat resistance and inner layer peeling strength.

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Claims (2)

[Claims] 1. A predetermined number of prepregs obtained by impregnating a thermosetting resin into a glass cloth are laminated, a copper foil is laminated on the outside of the prepreg, a circuit is formed on an inner layer plate integrally formed, and then the outer layer of the inner layer plate is formed. In order to improve the adhesion between the copper foil and the resin, in order to improve the adhesion between the copper foil and the resin, an etching treatment containing sulfuric acid, hydrogen peroxide and a corrosion inhibitor was carried out to improve the adhesion between the copper foil and the resin. A method for producing a multilayer printed wiring board, comprising treating with a liquid, further treating with an alkaline solution, and then integrally molding the multilayer board. 2. The method according to claim 1, wherein the etching solution contains a water-soluble polymer together with sulfuric acid, hydrogen peroxide and a corrosion inhibitor.