JP2000328268A - Etching treating agent for copper and copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the corrosion of a circuit even in the case water-washing after treatment is insufficient and to avoid trouble such as disconnection or the like by composing this agent of an aq. soln. contg. the ferric complex of a complexane compd., halogen ions and/or an imidazole compd. as essential components and controlling the pH of the soln. to a specified range. SOLUTION: A complexane compd. works as an oxidizer for copper and a copper alloy by forming a complex with ferric ions in an aq. soln. of pH 5 to 8, dissolves metallic copper oxidized by the ferric complex and stably makes it soluble as the copper complex of the complexane compd. As the complexane compd., iminodiacetic acid or the like can be given. An imidazole compd. has the action of increasing the oxidizing force of the ferric complex of the complexane compd. for copper and a copper alloy and moreover dissolving the oxidized metallic copper, and imidazole or the like can be given. Halogen ions act similarly to the imidazole compd., and, as the ion source, sodium chloride or the like is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching agent for removing rust and roughening a copper surface and a copper alloy surface, and more particularly to a copper circuit portion in a printed circuit board in which copper, a copper alloy and solder coexist. It is suitable as a surface treatment agent.

[0002]

2. Description of the Related Art In the manufacture of printed wiring boards, micro-etching for chemically polishing a copper surface has been proposed for the purpose of improving the adhesion of an etching resist, a solder resist or the like, or improving the solderability when mounting electronic components. A called process is being performed. This micro-etching process usually involves an aqueous solution mainly composed of sulfuric acid and hydrogen peroxide,
Alternatively, an aqueous solution containing a persulfate as a main component is used. Surface treatment methods using sulfuric acid and hydrogen peroxide are described in JP-B-53-32340, JP-A-3-140481, and JP-A-5-295365. It is described in JP-B-61-435. In recent years, in order to mount an electronic component such as a QFP having a narrow lead pitch on a printed circuit board, a method of supplying solder to some lands in advance has been performed. Such a board to which solder has been supplied in advance is generally called a solder precoat board, and is a board in which copper and solder coexist. An etching agent for a substrate in which copper and solder coexist is described in JP-A-9-293954.

[0003]

The microetching agent containing sulfuric acid and hydrogen peroxide or persulfate as main components is
Although it has advantages such as a high etching rate of copper, it has the following disadvantages. If the washing after the etching is insufficient and the microetching solution remains on the substrate, the circuit is corroded, and in the worst case, the circuit is disconnected. When a substrate in which copper and solder coexist is processed, the surface of the solder is discolored. Since the treatment liquid is strongly acidic, sufficient care must be taken in handling.

A surface treatment agent for preventing circuit corrosion is disclosed in
-287774. However, there is a problem that processing is time-consuming due to the low etching rate of copper, and the productivity is lacking. A surface treating agent for a substrate in which copper and solder coexist is described in Japanese Patent Application Laid-Open No. 9-293954. However, this also has a similar problem because the etching speed of copper is low. The present invention does not corrode the circuit even if the water washing after processing is insufficient, avoids troubles such as disconnection, and furthermore, even when processing a board in which copper and solder coexist, the solder surface does not discolor. An object of the present invention is to provide a surface treatment agent capable of etching only copper, increasing the etching rate of copper, and improving the working environment.

[0005]

The present inventors have conducted various tests to achieve the above object, and as a result, have found that a ferric complex of a complexan compound, a halogen ion and an imidazole compound, or a complexan compound. Consisting of an aqueous solution containing a ferric complex of the formula (I) and either a halogen ion or an imidazole compound as essential components,
It was found that the intended purpose can be achieved by using an etching agent for copper and a copper alloy characterized by adjusting the ratio to a range of 5 to 8, and completed the present invention.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The ferric complex of a complexan compound used in the present invention acts as an oxidizing agent for oxidizing metallic copper and the like. In the present invention, by using a ferric complex of a complexan compound among various ferric complexes having an oxidizing action, a good etching rate can be exhibited as a surface treatment agent for copper and a copper alloy. Among the ferric complexes of the complexan compounds, iron compounds suitable for supplying ferric ions include iron (III) chloride, iron (III) bromide, iron (III) iodide, and iron sulfate (III), iron (III) ammonium sulfate, iron (III) nitrate, iron (II) citrate
I), ammonium iron (III) citrate, iron (III) perchlorate, iron (III) 2-ethylhexane and the like. Two or more iron compounds for supplying the ferric ion may be used in combination. The content of the iron compound that supplies ferric ion is 0.1 to 20% in terms of ferric ion.
Is preferred.

[0007] Among the ferric complexes of the complexan compound, the complexan compound acts as an oxidizing agent for copper and copper alloys by forming a complex with ferric ion in an aqueous solution having a pH of 5 to 8; It is used for dissolving copper metal oxidized by a ferric complex of a compound and stably solubilizing it as a copper complex of a complexan compound. Representative examples of the complexan compound include iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, 1,2-diaminocyclohexanetetraacetic acid, glycol ether diaminetetraacetic acid, N , N-bis (2-hydroxybenzyl) ethylenediaminediacetic acid, ethylenediaminedipropionic acid, ethylenediaminediacetic acid, diaminopropanoltetraacetic acid, hexamethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, diaminopropanetetraacetic acid, nitrilotripropionic acid, Examples thereof include ethylenediaminetetrakismethylenephosphonic acid, nitrilotrismethylenephosphonic acid, and salts thereof. The complexan compound is 2
More than one type may be used in combination. The content of the complexan compound is preferably 1 to 10 moles per 1 mole of the ferric ion (molar concentration).

The ferric complex of the complexan compound may be added as an iron complex, or the ferric ion source and the complexan compound may be added separately, and the ferric complex of the complexan compound may be added in an aqueous solution. May be generated.

The imidazole compound used in the present invention is used to increase the oxidizing power of the ferric complex of the complexan compound to copper and copper alloy and to dissolve oxidized metallic copper. Representative examples of the imidazole compound include imidazole, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole,
2-propylimidazole and the like. Two or more imidazole compounds may be used in combination. The content of the imidazole compound is preferably 0.01 to 20%.

The halogen ion used in the present invention is used for increasing the oxidizing power of the ferric complex of the complexan compound to copper and copper alloy and for dissolving oxidized metallic copper. Compounds suitable for supplying the halogen ions include sodium fluoride, potassium fluoride, sodium chloride, calcium chloride, potassium chloride, ammonium chloride, barium chloride, iron chloride, copper chloride, zinc chloride, potassium bromide, and odor. Examples include ammonium iodide, barium bromide, copper bromide, iron bromide, sodium iodide, potassium iodide, ammonium iodide, calcium iodide, and compounds capable of dissociating halogen ions in a solution. Two or more compounds that supply the halogen ions may be used in combination. The content of the compound that supplies a halogen ion is preferably 0.001 to 20% in terms of a halogen ion.

The organic acid used in the present invention is used for dissolving metallic copper oxidized by a ferric complex of a complexan compound. Representative organic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, heptanoic acid, caprylic acid, capric acid, lauric acid, glycolic acid, lactic acid, chloroacetic acid, acrylic acid, oxalic acid, malonic acid Acids, succinic acid, glutaric acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, benzoic acid, paranitrobenzoic acid, phthalic acid, salicylic acid, picric acid, glycine, alanine, gallic acid and the like. The content of the organic acid is preferably 0.1 to 30%.

The complexing agent used in the present invention is for stably solubilizing copper ions dissolved by etching. Examples of the complexing agent include aliphatic amines such as butylamine, dibutylamine and triethylamine, alkanolamines such as monoethanolamine, diethanolamine and triethanolamine, and amino acids such as glycine and alanine. The content of the complexing agent is preferably 1 to 20%.

The additives used in the present invention are used to improve the appearance of copper by etching. The additive is a surfactant, a polymer compound, or the like. Examples of the surfactant include a nonionic surfactant such as polyoxyethylene sorbitan monolaurate, an anionic surfactant such as sodium laurate, and a cationic surfactant such as trimethylbenzylammonium chloride. Examples of the polymer compound include polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, gelatin, and soluble starch. The content of the additive is 0.0
01 to 10% is preferred.

The surface treating agent of the present invention comprising the above components should be used after adjusting to an aqueous solution having a pH of 5 to 8 (20 ° C.) by adding sodium hydroxide, ammonia, the above-mentioned organic acid and the like.

The method of using the surface treating agent of the present invention includes:
A method of spraying the substrate to be processed by a spray and a method of immersing the substrate to be processed in a surface treatment agent are preferable. In the case of immersion, air is preferably blown by bubbling or the like in order to oxidize ferrous ions generated in the liquid by etching into ferric ions.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples 1 to 5 The components shown in Table 1 were mixed and adjusted to pH 7 to prepare a surface treating agent. Height 140
mm, width 100mm, thickness 1.6mm, hole diameter 0.8mm
A substrate having 1,000 through holes was prepared. After covering one surface of the substrate with a solder resist, the substrate was immersed in the surface treatment agent at 40 ° C. for 1 minute. Next, this substrate was heated at 230 ° C. for 5 minutes without being washed with water, and was heated at 85 ° C. and 85%
The rate of occurrence of disconnection of the through-hole was determined by measuring the resistance in the through-hole after being left in a constant temperature and humidity chamber of RH for 30 days. Table 1 shows the results. A solder-copper mixed board having a length of 70 mm, a width of 50 mm, and a thickness of 1.6 mm was added to the surface treatment agent by 4
It was immersed at 0 ° C. for 1 minute, and the discoloration of the solder surface and the etching rate of copper were examined. Table 1 shows the results.

Comparative Examples 1 to 3 The components shown in Table 1 were mixed to prepare a surface treating agent. Evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 4 The components shown in Table 1 were mixed, and p
Adjusted to H6.5. Evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

[0020]

[Table 1]

[0021]

The etching treatment agent of the present invention has no fear of corroding the circuit even when the washing after treatment is insufficient. Further, even when the solder is processed, the surface thereof hardly discolors, and is a surface treatment agent suitable for a copper-solder mixed board. Further, since the pH of the processing solution is adjusted to a neutral range of 5 to 8, the working environment can be dramatically improved.

Claims (2)

[Claims] 1. An aqueous solution comprising a ferric complex of a complexan compound, a halogen ion and an imidazole compound, or an aqueous solution containing a ferric complex of a complexan compound and either a halogen ion or an imidazole compound as essential components. Was adjusted to the range of 5 to 8, and an etching treatment agent for copper and a copper alloy. 2. An aqueous solution containing a ferric complex of a complexan compound, a halogen ion and an imidazole compound, or a ferric complex of a complexan compound and either a halogen ion or an imidazole compound as an essential component, an organic acid or a complex. A surface treating agent for copper and copper alloys, wherein one or more of an agent, a surfactant and a polymer compound are added to adjust the pH of the solution to a range of 5 to 8.