JPH0590758A - Production of multilayered printed-board - Google Patents

Abstract

PURPOSE:To provide a multilayered printed board in which hollowing is reduced by applying hydrazine treatment on an electroless plating through-hole board. CONSTITUTION:The copper foil surface of internal layer in which a printed wiring net is formed as an intermediate layer is oxidized chemically to form a brown or black copper oxide surface thereon, and after multilayered lamination formation is performed, throughhole making, desmear treatment, electroless plating, and electrolytic plating are applied in sequence to obtain an outer-layer printed wiring net. Through the production method of multilayered printed wiring board including the above processes, the treatment of hydrazine solution is further added between the processes of electroless plating and electrolytic plating in order to reduce hollowing in the multilayered printed board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a method of treating with an aqueous hydrazine solution between electroless plating and electrolytic plating.
This is a method of manufacturing a multilayer printed board in which the "halo" or "pink ring" phenomenon is prevented from increasing in the electrolytic plating process, and the haloing of about 200 to 300 µm can be set to 100 µm or less.

[0002]

2. Description of the Related Art In a multi-layer printed board, a method for improving the multi-layered adhesive strength of an inner layer board having a printed wiring network formed thereon is to use a copper foil whose both surfaces have been previously roughened; a printed wiring network for an inner layer is formed. After doing. A method of forming a copper oxide film on the surface of a copper foil with an oxidation treatment aqueous solution ,. A method of treating the copper foil surface with a silane-based or organic titanate-based coupling agent is known, but conventionally, from the viewpoint of adhesiveness and economy, a copper-clad laminate having a glossy surface is usually used for the inner layer. After forming a printed wiring network, it is treated with an oxidizing alkaline aqueous solution to form a brown or black copper oxide film.

However, when this copper oxide film is used, a so-called "halo" or "pink ring" is apt to occur after the completion of the through-hole plating, which causes a decrease in the reliability of the printed wiring board such as insulation. There was a drawback.
Recently, as a method for preventing the halo that is likely to occur when this brown or black copper oxide film is used ,. A method of reducing the copper oxide film on the surface of the copper foil obtained in step 1) with an aqueous reducing agent solution to convert it to a cuprous oxide film or a copper film (JP-A-56-153797)
No., etc.) has been disclosed. Although these methods can achieve a practically applicable level of adhesive strength, they require a new liquid-phase reduction treatment step, and the adhesive strength is lower than that of a brown or black copper oxide film. It is necessary to make the reducing conditions extremely strict to obtain an adhesive strength that can withstand aging. Furthermore, the effect of preventing the occurrence of "halo" varies, and a new problem of waste liquid treatment of the reducing agent aqueous solution occurs.

[0004]

Therefore, the present inventors have adopted a simpler method that can be applied as it is to the manufacturing process of the currently used multilayer board, and that can keep the "halo" below the normal allowable level. To provide.

[0005]

As a result, the present inventors have found a method of introducing a hydrazine aqueous solution treatment immediately after the electroless plating step, and completed the present invention. That is, the present invention, the copper foil surface of the inner layer plate on which the printed wiring network is formed as the intermediate layer is chemically oxidized to form a brown or black copper oxide surface, and after multilayer lamination molding, through hole punching, In a method for producing a multilayer printed wiring board, which comprises desmearing, electroless plating, and electrolytic plating to form an outer layer printed wiring network, characterized by treating with a dilute hydrazine aqueous solution between the electroless plating and electrolytic plating. And a method for producing a multilayer printed board with reduced haloing, wherein the hydrazine concentration in the hydrazine aqueous solution is 0.1.
~ 10% by weight.

The multi-layer printed wiring board of the present invention is an inner layer board having an inner layer printed wiring network used as an intermediate layer. After the copper foil surface is chemically oxidized to form a black or brown copper oxide surface, Through prepreg used for multi-layer adhesion, prepreg for forming outer layer and laminated material such as copper foil or single-sided copper clad laminate, and multilayer printed wiring board with copper foil on both outer surfaces manufactured by laminate molding method, etc. It is a hole-drilled, desmeared, and then electroless plated, and is the most commonly used conventional product. A known method is also used as a method for forming a brown or black copper oxide film on the inner layer plate used in the present invention.

According to the present invention, a through-hole is formed in a multilayer board laminated and formed by the conventionally known method as described above, desmear treatment is carried out, and then hydrazine aqueous solution treatment is carried out after electroless through-hole plating. Examples of the hydrazine used include anhydrous hydrazine, hydrazine monohydrate, hydrazine carbonate or methylhydrazine,
The hydrazine concentration is in the range of 0.01 to 30%, preferably
A range of 0.05 to 20%, particularly 0.1 to 10% is preferable. Further, it is preferable that the processing time be matched to the flow of the process,
The hydrazine concentration, treatment temperature, etc. are determined so that the range is usually 1 to 30 minutes, especially 2 to 20 minutes. When the hydrazine concentration is suitable, immersion does not cause any new problems even for about 2 to 3 hours, and the treatment time can be about 5 minutes.

As described above, the electroless-plated multilayer board treated with the aqueous hydrazine solution of the present invention is made into a multilayer printed wiring board by a method of forming a printed wiring pattern on both outer surfaces after electrolytic plating.

[0009]

Example 1 A double-sided copper-clad glass-epoxy laminated board having a thickness of 0.8 mm and a copper foil thickness of 70 μm was formed with 10,000 mm through-hole land series inner layer printed wiring patterns of 2.0 mm by a known etching method, and wiring The pattern copper surface is conventionally known N
It was treated with an aqueous solution of aOH (15 g / liter / sodium hypochlorite (31 g / liter) / sodium phosphate (15 g / liter) at 90 ° C. for 5 minutes and washed with water to obtain a black oxidized inner layer plate. After drying the oxidation-treated inner layer board at a temperature of 130 ° C for 30 minutes, glass epoxy prepreg (resin amount 52%, thickness 0.1
mm) 3 sheets, and further layer 18 μm thick electrolytic copper foils on top of each other, and
After laminating at 75 ° C. and a pressure of 40 kg / cm ² for 2 hours to form a 4-layer board, it was cooled.

This 4-layer board has a hole diameter of 0.4 mmφ and 80,000 rp.
m., 10,000 drill holes under the condition of 20 μm / revolution, then desmear treatment with a known permanganate-based desmear treatment solution, and use a known salt-based activation-less electroless plating solution. After electrolytic plating was performed, immersion treatment was performed by changing the concentration, temperature, and time of the hydrazine aqueous solution in the hydrazine aqueous solution treatment, and then electrolytic plating was performed. After using the obtained multilayer plate to remove all the copper on both outer surfaces and the walls of the through holes with a known alkali etching solution, haloing was observed. Also, for comparison, the same was applied to the case where the treatment was not performed with the hydrazine aqueous solution.

As a result of the above, the haloing was as follows under the processing conditions described on the right. (Actual) average 110 μm, maximum 200 μm: N ₂ H ₄ concentration 5
%, 50 ° C, 20 minutes. (Actual) average 123μm, maximum 150μm: N ₂ H ₄ concentration 2
%, 50 ° C, 10 minutes. (Actual) average 120μm, maximum 170μm: N ₂ H ₄ concentration 0.5
%, 70 ° C, 5 minutes. (Ratio) Average 200 μm, maximum 350 μm: without N ₂ H ₄ aqueous solution treatment.

[0012]

As described above, according to the detailed description and the examples, the multi-layer printed board according to the manufacturing method of the present invention has a significantly reduced "halo" and can be reduced to about 1/2 of the conventional one. Furthermore, the treatment with the aqueous hydrazine solution of the present invention can be directly applied to the existing process, and the consumption of hydrazine is extremely small. As described above, the multilayer printed wiring board with improved reliability can be implemented with high productivity and pollution-free without substantially changing the existing line, and has an extremely high industrial significance. ..

Claims (2)

[Claims] 1. A copper foil surface of an inner layer plate on which a printed wiring network is formed as an intermediate layer is chemically oxidized to form a brown or black copper oxide surface, which is subjected to multi-layer lamination molding, followed by through-hole drilling and desmearing. In a method for producing a multilayer printed wiring board, which comprises treatment, electroless plating, electroplating, and forming an outer layer printed wiring network, treatment with an aqueous hydrazine solution is performed between the electroless plating and the electrolytic plating. Method for manufacturing multilayer printed circuit board with reduced haloing 2. The method for producing a multilayer printed wiring board according to claim 1, wherein the hydrazine concentration in the hydrazine aqueous solution is 0.1 to 10% by weight.