JPH0429741B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a treatment method for improving the adhesion of a copper surface to be bonded to a resin, particularly a treatment suitable for improving the adhesion of a copper surface of an inner layer printed circuit board having an inner layer pattern. Regarding the law. (Prior art) Copper foils used for multilayer printed circuit boards in which printed circuit boards with necessary inner layer patterns formed in advance are embedded via prepreg have traditionally been double-sided roughened foils and single-sided roughened foils (electrolytic foils). It is used. However, double-sided roughened foil is easily damaged by handling during circuit processing. The rough surface lacks stability and is prone to rust. The disadvantage is that it is difficult to create fine fine patterns because the circuit is processed on a rough surface. With single-sided roughened foil, it is possible to create fine patterns because the circuit is processed on the glossy side. However, if the glossy surface remains as it is, sufficient adhesion strength cannot be obtained during multilayer bonding, so oxide film formation treatment is usually applied to improve adhesive strength, but the oxide film tends to deteriorate and has a short shelf life. There is a drawback. (Object of the Invention) An object of the present invention is to provide a method for surface treatment of copper that has excellent adhesion to resin layers such as prepreg. (Structure of the Invention) The present invention provides copper ions, copper ions,
This is a method for surface treatment of copper, which is characterized by bringing it into contact with an aqueous solution containing a complexing agent for copper ions, a reducing agent, hydroxide ions, and at least one selected from zirconium, bismuth, and compounds thereof. That is, the present invention deals with zirconium, bismuth, and their respective compounds such as zirconium oxide, zirconium silicate, zirconium tetrachloride, zirconium hydride, zirconium dioxide, zirconium oxychloride, zirconium nitrate, bismuth sulfate,
Copper ions, complexing agents for copper ions, hydroxide ions, and reducing agents containing at least one type selected from bismuth oxychloride, bismuth oxide, bismuth nitrate, bismuth chloride, basic bismuth carbonate, etc. This is a copper processing method characterized by bringing an aqueous solution containing the resin into contact with the surface of the copper to be bonded. To bring the aqueous solution into contact with the copper, there are a method of immersing the copper in the aqueous solution, a method of spraying the aqueous solution, and the like. In the present invention, common copper salts such as copper sulfate, copper nitrate, and cupric chloride are preferably used as the copper ion source. The complexing agent is preferably one that forms a complex with copper ions and is soluble in an aqueous alkaline solution, such as ethylenediamine-tetraacetic acid, N,N,N',N'tetrakis(2-hydroxypropyl)ethylenediamine, and tartaric acid. The purpose of the hydroxide ion is to adjust the pH of the treatment solution, and sodium hydroxide, potassium hydroxide, etc. are preferably used. Formalin, hypophosphite, etc. can be used as the reducing agent. The basic composition of the treatment solution containing these components is copper sulfate 2g/~20g/, ethylenediaminetetraacetic acid as a complexing agent at a molar concentration of 1 to 5 times the copper sulfate concentration, treatment solution pH 11.0 to 13.5, and as a reducing agent. It is preferable to use 2 ml/~20 ml/of 37% formalin. The amount of zirconium, bismuth, and each compound added may be 0.05g/or more, but considering handling and cost, it is recommended to add 0.5g/or more.
It is preferable to use it in the range of ~50g/. If a nitrogen-containing heterocyclic compound is further added to the composition of the present invention as an additive, the effect will be even better. These main compounds are 1,
10-phenanthroline, 4,7-dimethyl 1,10
-phenanthroline, αα′-dipyridyl,
Examples include αα′α″-tripyridyl, chlorinated copper phthalocyanine, and 2,4-dimethylimidazole.
These are 0.1 mg/or more, preferably 1 mg/~
Use 500mg/. Since the treatment solution composition of the present invention belongs to a so-called electroless plating solution, this treatment may sometimes cause abnormal copper precipitation or adhesion of impurities. This copper precipitation may cause abnormal conduction (shoot) between patterns, so post-treatments such as hydrochloric acid, sulfuric acid, acetic acid, cupric chloride, ferric chloride, ammonium persulfate, alkali metal chloride,
The treated surface can be leveled by performing treatment with a treatment liquid using an alkaline solution of a complexing agent and a reducing agent, or a combination of two or more of each.
Further, the copper to be treated may be any of electrolytic foils used in ordinary circuit boards, copper formed by electroless plating, electroplating, rolled copper, etc. The treatment according to the present invention is applicable not only to the pre-adhesion treatment of the inner layer copper foil of multilayer printed circuit boards, but also to the adhesion of copper and resist in the formation of resist for etching and soldering of copper-clad laminates, and the adhesion of copper and resist in the formation of resists for etching and soldering of copper-clad laminates. It can also be used to improve the adhesive strength of flexible films. Example 1 A copper-clad laminate that had been circuit-processed in advance was subjected to pretreatment of degreasing → surface smoothing (immersion in 100 g of ammonium persulfate/aqueous solution) → washing → drying. Copper sulfate 10g/, ethylenediaminetetraacetic acid 40g/,
After the circuit-processed copper clad laminate was immersed for 30 minutes in a bath in which 1 g of bismuth oxide was added to a basic treatment solution consisting of 5 ml of 37% formalin at a pH (room temperature) of 70°C and a pure water solution at a temperature of 70°C. % hydrochloric acid for 1 minute at room temperature. Example 2 Zirconium oxide 2g/, 1,
After immersing the circuit-processed copper clad laminate of Example 1 in a bath containing 10 mg of 10-phenanthroline for 20 minutes, 50 mg of post-treated ammonium persulfate was added.
g/aqueous solution for 3 minutes at room temperature. Comparative Example 1 Copper-clad laminate subjected to only the pretreatment of Example 1 Comparative Example 2 The circuit-processed copper-clad laminate of Example 1 was immersed in the basic treatment solution for 30 minutes. Comparative Example 3 Copper-clad laminate using double-sided roughened foil. Comparative Example 4 Copper foil surface subjected to black copper oxide film formation treatment. The characteristics of the substrates of the above Examples and Comparative Examples are shown in the attached table.

【table】

[Table] (Effects of the Invention) According to the present invention, the copper surface to be bonded to the resin is coated with copper ions, a copper ion complexing agent, a reducing agent, and at least one selected from zirconium, bismuth, and compounds thereof. By contacting with an aqueous solution, fine copper particles are deposited on the copper surface, improving adhesion with the resin. The present invention is effective not only for improving the adhesiveness of inner layer circuit boards of multilayer printed circuit boards, but also for improving the adhesiveness between copper foil and laminates, and for bonding copper and resin.

Claims (1)

[Claims] 1. Contacting the copper surface to be bonded with the resin with an aqueous solution containing copper ions, a copper ion complexing agent, a reducing agent, and at least one selected from zirconium, bismuth, and compounds thereof. Characteristic copper surface treatment method. 2. The copper surface treatment method according to claim 1, which comprises adding a nitrogen-containing heterocyclic compound to the aqueous solution.