JPS6115980A - Surface treatment of copper - Google Patents

Abstract

PURPOSE:To improve the adhesive property of the copper surface of a copper- lined laminated board or the like to a resin-base material such as prepreg by treating the copper surface with a soln. having a prescribed composition contg. a heterocyclic compound contg. nitrogen. CONSTITUTION:When a printed circuit board for an inner layer or the like is manufactured, the copper surface of a copper-lined laminated board or the like is roughened and immersed in a treating soln. prepd. by adding about 1-500mg/ lheterocyclic compound contg. nitrogen such as 4,7-dimethyl-1,10-phenanthroline to copper ions, a complexing agent, a reducing agent, hydroxyl ions and water as essential components. By the treatment, the copper surface is colored, in a color other than the colors of metallic copper and lustrous metallic copper. The adhesive property of the copper surface to a resin-based material such as prepreg is improved, and a printed circuit board for an inner layer giving an inner layer circuit with superior line accuracy is obtd.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is used in the production of multilayer printed wiring boards as a pretreatment for conductor circuits on inner layer circuit boards that are bonded in multiple layers through prepreg. This paper relates to surface treatment methods for copper.

(Prior Art) A multilayer printed wiring board is manufactured as follows. In other words, a copper clad laminate for the inner layer is made by processing the copper foil of an ordinary A6 copper clad laminate to form printed wiring, and the copper foil is treated with a chemical solution such as ammonium persulfate, cupric chloride, or copper acetate. After the surface of the copper foil is roughened, the copper-clad laminate for the outer layer is laminated and bonded to the copper-clad laminate for the inner layer via a thermosetting resin-impregnated base material (prepreg). In addition, in B, a steel-clad laminate for the inner layer is made by using a copper clad laminate using copper foil whose adhesion has been improved by roughening both sides of the copper foil (double-sided roughened copper foil) in the same manner as in A. Without roughening the surface of the copper foil, a steel clad laminate for external use is laminated and bonded to this steel clad laminate for inner layer via a prepreg. For *, a copper-clad laminate for the inner layer was made in the same manner as C0, and treated with the same chemical solution as A to roughen the surface of the copper foil, and then treated with a sodium chlorite-based treatment solution. It was manufactured by laminating and bonding a copper-clad laminate for the outer layer to a steel-clad laminate for the inner layer via a buripreg.

These methods had the following problems.

In the multilayer wiring board manufactured by method A, the contact strength between the inner copper foil and the resin layer made of hardened prepreg is insufficient. In addition, during the process of soldering various electronic components to the completed multilayer printed circuit board, peeling may occur between the circuit copper foil and the laminate, and in some cases, this peeling may be visible to the naked eye from the outside. In some cases, it appeared as a bulge on the board.

In method B, since double-sided roughened copper foil is used, in the process up to forming the printed wiring of the inner copper foil laminate,
The roughened surface may be scratched, and in that case, the adhesion strength will be reduced in the scratched area.Also, the pattern accuracy of the etching resist may be affected by the printing etching resist used for forming printed wiring or the UV photo printing method. , the copper foil surface was inferior due to its rough surface.

In the C0 method, after the copper foil laminate for the inner layer is subjected to a copper foil surface treatment, the pot life is short during which lamination can be bonded to the copper clad laminate for the outer layer via the prepreg without decreasing the adhesive strength.

(Object of the Invention) An object of the present invention is to provide a method for surface treatment of copper that improves adhesive strength with resin materials such as prepreg.

(Kirinari of the Invention) The present invention provides a treatment surface of copper by adding (a) copper ions, complexing agents, reducing agents, hydroxide ions, water, (b) (a) liquid. This is a method for surface treatment of hooks, which is characterized by treating with a liquid containing a nitrogen-containing heterocyclic compound capable of imparting a color other than metallic copper color and metallic copper luster.

The conductor of the wiring pattern of the copper inner-layer wiring laminated board processed in the present invention may be obtained by etching a copper-clad J-board, copper electroplating, electroless steel plating, or a combination thereof. Either one is fine. As a pre-process for the above copper surface treatment, water, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, citric acid, cupric chloride, sulfuric acid, etc. The treatment may be performed with an aqueous solution consisting of a combination of compounds selected from copper compounds such as copper, iron compounds such as ferric chloride and ferric sulfate, alkali metal chlorides, and ammonium persulfate. Further, instead of roughening, which is one of these chemical methods, mechanical methods such as liquid honing and polishing may be used.

In the treatment solution of the present invention, common copper salts such as steel sulfate, copper nitrate, and cupric chloride are used as copper ion sources. The complexing agent is one that forms a complex with the above-mentioned copper ion and becomes soluble in an alkaline aqueous solution, such as ethylenediaminetetraacetic acid, Quadrol (trade name, manufactured by Adeka), tartaric acid, and the like. Examples of reducing agents include formalin and hypophosphite. Further, hydroxide ions are added for the purpose of adjusting the quality of this treatment solution, and sodium hydroxide, potassium hydroxide, etc. can be used.

Ion-exchanged water is preferable as water. The basic composition of the treatment liquid consisting of these components is, for example, copper sulfate 2g/l.
~20 g/l, 11.0 to 1&5 of the processing solution, 1.0 to 5.0 times the molar concentration of copper sulfate in the case of ethylenediaminetetraacetic acid as a complexing agent, and 37% as a reducing agent.
Formalin has a concentration of 2 ml/l to 2 [1 ml/J is preferred.

In addition, nitrogen-containing heterocyclic compounds that can be colored, for example, brownish-brown, grayish-brown, bluish-purple, blue-black, and blackish-brown, include 2.4.6-tris(2-pyridyl)-s.
-triazine, α, d,/-tripyridyl, i, io-
Phenanthroline, 4.7-diphenyl-1,10-phenanthroline, 4゜7-dimethyl-1.10-phenanthroline, 4゜7-diphenyl-1,10-7 enanthroline, disodium salt of disulfate, 3-(2-pinudyl)-5,5-diphenyl-1,2,4-)riazibe αd
-dipyridyl, rγ'-dipyridyl, chlorinated copper phthalocyanine, 2,4-dimethylimidazole, and mixtures thereof.

However, the compounds listed here are not all nitrogen-containing heterocyclic compounds that have a similar structure and can be added to color the treated surface of copper in a color other than metallic copper color and metallic copper luster. can also be used. The addition amount may be Q, 1rr@/1 or more. Since many of these chemicals are relatively expensive, it is not preferable to add them in large amounts from the viewpoint of cost. Generally, a range of 1ffIg/l to 500mg/J is preferred.

All of these chemicals are commercially available from companies such as Jin Kagaku Kenkyusho and Tokyo Kasei Kogyo.

The temperature of the processing solution is mainly related to the concentration of the processing solution and the reducing agent, and if the concentration of the reducing agent is high, processing can be performed even at low temperatures. Therefore, the temperature can be selected from room temperature to 90°C depending on the composition of the processing liquid.

This processing solution belongs to the electroless copper plating solution, and if the composition of the processing solution is kept constant, the weight increases with the processing time due to plating precipitation. This point differs from conventional processing liquids because the weight of conventional processing liquids decreases.

The processing time is related to the plating deposition rate of the processing solution. Further, since it is preferable that the treatment step be short, the immersion time in the treatment liquid is generally 2 minutes to 60 minutes.

The present invention has been described above with respect to the treatment of the conductor of the wiring pattern of a laminate with inner layer wiring, but the treatment liquid of the present invention improves the adhesive strength between copper and resist when forming a resist for etching or plating of a copper-clad laminate. It can also be used for surface treatment of copper to strengthen the adhesive strength between copper and solder resist in reinforcement and solder resist formation for printed wiring boards.

That is, after forming the inner layer circuit by an etching method or an additive method, the process of the present invention is performed, and an insulating resin such as a resist ink or an adhesive is applied or attached by a screen printing curtain coating method or a hot roll laminating method. Adhesion between the copper circuit and the above material can be ensured. If a conductor is formed on the outer layer of the product thus obtained by a conventional method, a multilayer board can be manufactured without a pressing process.

In addition, we also deal with the treatment of the surface of copper foil that comes into contact with prepreg when manufacturing copper-clad laminates by laminating and bonding copper foil and prepreg, and the treatment of copper foil and prepreg when manufacturing substrates for flexible wiring boards by bonding copper foil and flexible film. It can also be used to treat the surface of foil that comes into contact with the film.

Example 1 A copper-clad laminate using an epoxy resin was roughened in advance with ammonium persulfate. Next step basic bath composition (2) is 4,7-dimethyl-1,1o-7 enanthrine 3■/j
It was immersed in the added treatment liquid (70±2°C) for 10 minutes.

Basic bath composition diagram Cu5O<'5H20: 10 g/1EDTA
e2Na: 40 g/IF4 ((room temperature): 12.
0 37% HCHO: 5 rnl/1 Pure water: total amount of 11 The color of the copper surface obtained by edge treatment, the tape test which is an adhesion test of the treated surface, and the lamination with no decrease in adhesion after treatment. Table 1 shows the preservability test results indicating the length of pot life that can be bonded. Tape Test) + 2. Attach a 10 mm wide Mylar tape with adhesive (manufactured by Nitto Denko) to the treated surface, keep the tape in close contact with the treated surface until the pasted tape becomes transparent, then gently peel it off and remove the adhesive. This is a method to check the amount remaining on the treated surface.

Treated surfaces with a large amount of residual material have high adhesive strength when manufacturing multilayer printed wiring boards.゛The evaluation criteria were as follows: No adhesive remained: ×; A little adhesive remained; ◎: About half remained over the entire surface of O1.

Storage stability was determined by performing the tape test described above after leaving the product at room temperature and humidity for 7 days, and examining the amount of adhesive remaining on the treated surface using the same evaluation method as the tape test.

Example 2゜To the same basic bath composition (5) as in Example 1, 10011 g/J of i,1o-phenanthroline was added to the treatment solution.
A copper-clad laminate was treated by pressing in the same manner as in Example 1, except that it was immersed in portions. Color of the surface of the treated hook, tape test,
Table 1 shows the storage stability test results.

Examples & Copper-clad laminates were prepared in the same manner as in Example 1, except that they were immersed for 10 minutes in a treatment solution in which α,l-dipyridyl was added at 10 μ/l to the same basic bath composition (4) as in Example 1. Processed. Table 1 shows the surface color, tape test, and preservability test results of the treated copper.

Example 4゜The same basic bath composition (8) as in Example 1 except that 2.4.6-tris(2-pyridyl)-5-)riazine was added at 20 μ/l to the treatment solution for 5 minutes. A copper clad laminator was processed in the same manner as in Example 1. Table IK shows the surface color, tape test, and storage stability test results of the treated copper.

Example 5 To the same basic bath composition (2) as in Example 1, 10 μ/e of 6-(2-pyridyl)-5,6-diphenyl-1.2.4-) riazine was added to the treatment solution. A copper clad laminator was treated in the same manner as in Example 1, except for soaking for a minute. Table 1 shows the surface color, tape test, and storage stability test results of the treated copper.

Comparative Example 1 A copper-clad laminate using an epoxy resin was roughened with ammonium persulfate. Table 1 shows the results of examining the surface color, tape test, and storage stability of this copper.

Table 1 below. Example 6 A copper-clad laminate using epoxy resin (a double-sided board 9 with an inner layer circuit formed to form a printed circuit) was treated by the following method.

Degreasing → ammonium persulfate roughening → water washing → basic bath composition (A
) K4,7-dimethyl-1,10-phenanthroline 1
Immerse for 10 minutes in a bath at 70°C containing 0 ■/l → Wash with water → Dry (30 minutes at 100°C) This printed circuit board was heated and pressurized (pressure: 60 kg/m, temperature: 170°C) using the configuration shown in the drawing.
, time 120 minutes) to create a multilayer printed wiring board. Table 2 shows the properties of the obtained multilayer printed wiring board.

Comparative Example 2 A copper-clad laminate (double-sided board) using epoxy resin with a trap inner layer circuit formed thereon to form a printed circuit was treated by the following method.

Degreasing → roughening with ammonium persulfate → washing with water → drying (100℃)
50 minutes). Using this printed circuit board, a multilayer printed wiring board was produced by bonding the layers in the same manner as in Example 6. The properties of this product are shown in Table 2.

Comparative Example 3 A printed circuit in which an inner layer circuit was formed on a copper-clad laminate (double-sided board) using an epoxy resin was treated by the following method. Degreasing → roughening → washing with water → (sodium hydroxide 05% trisodium phosphate 1% sodium decachlorite 5%) immersion in aqueous solution at 70°C for 1 minute → washing with water → drying (30% at 100°C)
Using this printed circuit board, a multilayer printed contact board was fabricated using the same method as in Example 6, with multilayer adhesive bonding. The properties of this product are shown in Table 2.

Comparative Example 4 An epoxy resin steel-clad laminate (double-sided board) using double-sided roughened copper foil with an inner layer circuit formed and a printed circuit was bonded in multiple layers in the same manner as in Example 6 to form a multilayer printed wiring board. Created. The properties of this product are shown in Table 2.

Table 2 (Effects of the invention) As explained above, in the present invention, the adhesion between resin materials such as prepreg and copper is improved, and in multilayer printed boards, the line precision of inner layer circuits is excellent, A printed circuit board for inner layer with excellent adhesive strength and storage stability can be obtained.

[Brief explanation of the drawing]

The drawing is a cross-sectional view showing a method of manufacturing a multilayer board. ・Explanation of symbols 1. Inner layer circuit board 2. Circuit steel foil on the inner layer circuit board 3 Prepreg 4 Copper foil Engraving of FA side (no change in content) talent (blade) Procedural amendment book 2) November 7, 1980

Claims (1)

[Claims] 1. The copper surface is treated by adding (a) copper ions, a complexing agent, a reducing agent, a hydroxide ion, water, and (b) (a) to the treated surface of the copper. A method for surface treatment of copper, characterized by treating with a liquid containing a nitrogen-containing heterocyclic compound capable of imparting color other than metallic copper luster.