JPH0444295A - Manufacturing of multi-layer printed circuit board - Google Patents

Abstract

PURPOSE:To improve the adhesion between a copper-clad laminate for interior materials and a resin layer by means of surface treatment process of interior copper pattern part, which consists of oxidation treatment of a copper pattern part, prior treatment for electroless plating, and electroless copper plating treatment. CONSTITUTION:Oxidation treatment 1 is applied to a copper pattern of a copper- clad laminate, and a rugged film of copper oxide is formed. Then, after the application of hot water bath treatment 2, deposition treatment of catalyzer for electroless plating (prior treatment) 3 is applied. Successively, chemical copper plated film is formed, by electroless copper plating treatment 4, on the surface of the recessed or projected part of copper oxide. Next, water bath treatment 5 is applied, and then dry treatment 6 is applied. In this way, the surface treatment process is completed.

Description

[Detailed Description of the Invention] [Summary] A method for manufacturing a multilayer printed wiring board, more specifically, a method for manufacturing a multilayer printed wiring board, more specifically, a method for manufacturing a multilayer printed wiring board, in which a copper foil or a copper clad laminate for an outer layer, a prepreg, and a copper clad laminate for an inner layer are laminated and hot pressed before being hot pressed. Regarding the surface treatment of the inner layer copper pattern part of the inner layer copper clad board performed in With the aim of preventing The method is configured such that a pretreatment for electroless plating is performed, and an electroless copper plating treatment is performed.

[Industrial application field]

The present invention relates to a method for manufacturing a multilayer printed wiring board, more specifically, a method for producing a copper clad laminate for an inner layer, which is performed before laminating and hot pressing a copper foil or a copper clad laminate for an outer layer, a prepreg, and a copper clad laminate for an inner layer. This invention relates to surface treatment of an inner layer copper pattern portion.

In multilayer printed wiring boards, we improved the adhesion between the copper pattern part of the inner layer board and the adhesive resin of the prepreg, especially for soldering of parts such as semiconductor devices (260
It is necessary to not peel off even when soldering temperature (℃).

[Conventional technology]

In the conventional surface treatment of the inner layer copper pattern portion, copper is chemically (oxidized) treated to form an uneven surface oxide film of copper oxide (CaO2 black) or cuprous oxide (Cu20, brown). These oxidation treatments are known as black oxide treatment and brown oxide treatment.

A prepreg is placed on the copper-clad laminate for the inner layer that has been subjected to such surface treatment, and then the copper-clad laminate for the outer layer is placed on top of the prepreg and heated and pressed to form a laminate. The outer shape of the laminate is processed, through-holes are drilled, and through-hole plating is applied. Then, a multilayer printed wiring board is manufactured by forming circuit pattern wiring using the outer layer copper plate.

[Problem to be solved by the invention]

In a laminate made by hot pressing, the copper oxide surface of the inner layer copper pattern part is covered with prepreg resin, but when drilling holes to create through holes, the processing load (impact) causes the oxide surface to bond with the prepreg resin. A gap may occur between the resin and the resin.

Then, when immersion or flowing (pickling) in an acidic treatment liquid is performed as a pretreatment for through-hole plating, the acidic liquid (hydrochloric acid, etc.) penetrates into the gap and dissolves the copper oxide. In the areas where the underlying copper is exposed due to this copper oxide dissolution (copper smooth surface areas), adhesion (adhesive force) will be insufficient, and in the worst case,
Laminated resin layers may peel off due to heating and cooling (thermal shock).

An object of the present invention is to provide an inner layer copper pattern with an uneven surface that is not dissolved by an acidic treatment solution used in through-hole plating pretreatment, and to prevent the above-mentioned defects from occurring.

[Means to solve the problem]

The above-mentioned purpose is that in the manufacturing process of a multilayer printed wiring board, the step of surface-treating the inner layer copper pattern part after forming the inner layer circuit of the copper-clad laminate for inner layer material is to oxidize the copper pattern part beforehand, and then This is achieved by a method for producing a multilayer printed wiring board, characterized in that it comprises performing a pretreatment for electroless plating, and performing an electroless copper plating treatment.

[For production]

According to the present invention, the uneven copper surface is added by depositing chemical copper by electroless plating on the uneven copper oxide surface formed by the conventional oxidation treatment of the inner layer copper pattern portion.

The chemical copper on this surface does not dissolve in the acidic treatment solution and reflects the previously formed uneven surface as it is, so there is no reduction in adhesion.

〔Example〕

Hereinafter, the present invention will be described in detail by embodiments and comparative examples with reference to the accompanying drawings.

FIG. 1 is a process diagram (flowchart) for surface treatment of the inner layer copper pattern portion according to the manufacturing method of the present invention, and the subsequent process is lamination hot pressing.

A double-sided copper-clad laminate made of an epoxy resin glass substrate manufactured by a known method is prepared, and copper M (inner layer copper plate) is formed into a predetermined circuit pattern portion by photoetching. In addition, in order to examine the adhesion method (force), we will compare the peel strength, so we used commercially available electrolytic copper foil (thickness 35μ).
Apply the same surface treatment as the lower surface using.

First, a conventional oxidation treatment 1 is performed on a copper pattern portion of a copper-clad laminate to form a copper oxide uneven coating. For example, 5
A concavo-convex film of CuO-based black oxide (or Cu2O-based brown oxide) is formed using an oxidation treatment solution (80° C. x 5 minutes) using Probond (process product name) manufactured by Hipley. Hot water washing treatment (60℃ x 2 minutes) 2
After that, electroless plating catalyst deposition treatment (pretreatment) 3 is performed. For example, Japan Schering's glue Reducer Neo Gant Ka^ (1) [25°C x 5 minutes] and Reducer Neo Gant Monument^ (2) [25°C x
2 minutes] Perform catalyst adhesion treatment using (process product name). Subsequently, a chemical copper plating film is formed on the uneven surface of the copper oxide by electroless copper plating process 4. This plating film has the underlying irregularities as they are. For example, Japan 5cher
25 using Novigan HC liquid (trade name) from ing Co., Ltd.
Approximately 0.2 mm thick by electroless copper plating treatment for 10 minutes at ℃
- forms a chemical copper plating film. Then, wash with water (room temperature x 2 minutes) 5 and dry (60-70℃
Step 6) is performed to complete the surface treatment process.

Prepreg (epoxy resin) is placed on such a surface-treated copper-clad laminate (or electrolytic copper foil) for inner layer material, and then pressurized and heated to completely cure the prepreg resin to form a laminate (note: (Since we are examining the adhesion between the surface-treated inner layer copper pattern and the resin layer, the lamination of the copper-clad laminate for the outer layer material is omitted.) As a result of conducting a copper foil peeling test on the electrolytic copper foil laminate obtained in this process, the peeling strength was, for example, 1.2 to 1.5 kg for Sample 1 (invention) in Table 1. / cm.

The manufactured laminate is processed into an external shape and the specified through holes are drilled. In order to apply through-hole plating to the perforated laminate in a known manner, the inner walls of the holes are immersed in an acidic treatment solution (for example, hydrochloric acid). At this time, since the copper oxide film is covered with chemical copper, it does not dissolve in the acidic treatment solution. Subsequently, an electroless plating catalyst adhesion treatment and an electroless copper plating treatment (the same conditions as the above-mentioned treatment may be used) are performed. In this way, the through-hole plated laminate is
We investigated whether the cured resin layer would peel off from the copper-clad laminate for inner layer material by applying thermal shock at 60℃ x 30 seconds x 5 cycles.As a result, the laminate made under the above conditions (Sample 1) did not peel off. I didn't.

As a comparative example (Sample 2), in the case where only the conventional oxidation treatment was performed, omitting the electroless plating treatment and its pretreatment (catalyst attachment treatment) in the surface treatment according to the present invention, the peel strength was 1. Although it was almost the same as 2 to 1.5 kg/cm, a pink ring (exposure of the underlying copper) was generated in the inner layer copper pattern part of the through hole, and it peeled off in the thermal shock test after through hole plating.

As shown in Table 1 above, according to the surface treatment of the present invention, there is no decrease in peel strength compared to the conventional method, and adhesion can be improved so that peeling does not occur in a thermal shock test.

From these facts, it is clear that the surface treatment of the inner layer copper pattern portion in the present invention is excellent, and can naturally be applied to multilayer printed wiring boards manufactured including copper clad laminates for outer layer materials.

〔Effect of the invention〕

As described above, according to the present invention, by depositing chemical copper on the conventional copper oxide uneven surface in the inner layer copper pattern part, the copper-clad laminate for inner layer material and the resin layer can be separated. It is possible to manufacture a multilayer printed wiring board with improved adhesion and reliability.

[Brief explanation of drawings]

FIG. 1 is a process diagram of surface treatment of an inner layer copper pattern portion according to the method of manufacturing a multilayer printed wiring board of the present invention. 1... Oxidation treatment, 3... Catalyst adhesion treatment for electroless plating, 4... Electroless copper plating treatment.

Claims (1)

[Claims] 1. In the manufacturing process of a multilayer printed wiring board, the step of surface-treating the inner layer copper pattern portion after forming the inner layer circuit of the copper-clad laminate for inner layer material includes oxidizing the copper pattern portion (1), and then electroless plating. 1. A method for manufacturing a multilayer printed wiring board, which comprises performing a pretreatment (3) and an electroless copper plating treatment (4).