JPH0593280A - Surface treatment of metal - Google Patents

Abstract

PURPOSE:To prevent the rusting of the surface of a metal and to improve its solderability by treating the metal surface with a preflux soln. contg. a 2-(3-methylbutyl)benzimidazole-based compd. CONSTITUTION:A compd. shown by the formula or its derivative is dissolved in a solvent as the effective component to prepare a preflux soln. The surface of a metal is treated with the soln., or the complex is formed after the surface treatment. The preflux is excellent in heat resistance, the rusting of the exposed metal part of a printed wiring board, etc., is prevented, and the solderability is improved. Besides, the preflux soln. is appropriately used as the sealing agent for the pinholes, etc., of a connector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment of metal, and is particularly suitable as a heat-resistant preflux for preventing the circuit portion of a printed wiring board made of copper or copper alloy from rusting and improving solderability. Is.

[0002]

2. Description of the Related Art Pre-flux, which has been conventionally used for the purpose of preventing corrosion of a circuit portion made of copper or a copper alloy of a printed wiring board and maintaining solderability, is roughly classified into rosins for coating the entire printed wiring board. System preflux,
There are two types of alkylimidazole-based preflux that selectively chemically react with copper or copper alloys. For the former, apply natural rosin, rosin ester, rosin-modified maleic acid resin, etc. dissolved in an organic solvent with a roll coater, or spray or dip it on the entire printed wiring board and dry to form a film. Used in the method. Therefore, there is a drawback that the working environment and safety are significantly impaired by the volatilization of the organic solvent. The rosin-based preflux also has a drawback that it involves a risk of ignition during work because it uses a volatile solvent. On the other hand, the alkylimidazole-based preflux is water-soluble and is excellent in terms of working environment and safety, but when the chemically reacted alkylimidazole copper complex is exposed to high temperatures, it is a catalyst for oxygen and copper in the air. It deteriorates by the action and inhibits the action of postflux,
It has the drawback of deteriorating the solderability.

[0003]

Recently, a surface mounting method has been widely adopted as a method for soldering an electronic component to a printed wiring board. The surface mounting method, the reflow of solder paste solder for electronic components, the printed wiring board is often exposed to high temperatures, and the heat resistance of the pre-flux used to maintain the solderability of the printed wiring board, That is, the pre-flux performance is required to have excellent solderability after the printed wiring board is exposed to high temperature. Further, it is desired to develop a preflux which does not use a volatile solvent having a problem in air pollution and has excellent solderability even after being exposed to a high temperature.

[0004]

In view of such circumstances, the inventors of the present invention have made extensive studies on a preflux which does not use a volatile solvent and has good solderability even after being exposed to a high temperature. As a result, acetic acid, capric acid, glycolic acid,
Paranitrobenzoic acid, paratoluenesulfonic acid, picric acid, oxalic acid, formic acid, succinic acid, phosphorous acid, maleic acid,
Acrylic acid, fumaric acid, tartaric acid, adipic acid, lactic acid,
Organic acids such as oleic acid, hydrochloric acid, sulfuric acid, phosphoric acid, or zinc acetate, lead acetate, zinc hydroxide, lead hydroxide, zinc sulfide, zinc phosphate, zinc oxide, zinc chloride, ferrous chloride, ferric chloride ,
Ferrous oxide, ferric oxide, cuprous chloride, cupric chloride, cuprous oxide, cupric oxide, copper hydroxide, copper phosphate, copper carbonate,
At least one liquid selected from the group consisting of an aqueous solution containing a metal compound such as copper acetate and copper sulfate, or a water-soluble solvent such as methanol, ethanol, isopropyl alcohol, butanol, and acetone, and 1)
When a solution prepared by mixing one kind or two or more kinds of the compounds represented by the above is used as a metal surface treatment agent, it was found that the above-mentioned conventional problems can be solved and the intended purpose can be achieved, and the present invention has been completed. It has come to do. (Chemical formula 1)
The above-mentioned organic acids used for solubilizing or emulsifying the compound represented by are organic acids, salts of organic acids,
Alternatively, water-soluble solvents such as alcohols can be used alone, respectively, or can be mixed and used at an arbitrary ratio. For example, the water-soluble solvent may be used alone or in combination with an organic acid or the like. Particularly, when the organic acid or the like is used alone, 2- (3-methylbutyl) benzimidazole, 2
-(3-Methylbutyl) tosylimidazole, 2- (3
When it becomes difficult to dissolve -methylbutyl) xylylimidazole or its derivative, it is preferable to add a water-soluble solvent, and in this case, the content ratio is often 0 to 50%. The solution obtained by dissolving each of the above-mentioned solvents contains 0.01 to 40 of the above-mentioned active ingredient.
%, Preferably 0.5 to 5% of a solubilized solution or an emulsified solution is generally used for the immersion treatment. The immersion is performed at a temperature range of 0 to 100 ° C. for an immersion time of several seconds to several tens of minutes. The range is appropriate. After forming the chemical conversion film, oxidize infrared rays / near infrared rays / far infrared rays / ultraviolet rays to 0-3.
In the temperature range of 00 ° C, a treatment range of several seconds to several tens of minutes is suitable. An exposure treatment range of a few seconds to a few tens of minutes is suitable for ozone O ₃ . The range of treatment with a chemical solution such as immersion and spraying for several seconds to several tens of minutes in a concentration of hydrogen peroxide water of 1 to 20% is appropriate. By performing the treatments 1 to 3, a chemical conversion coating having excellent heat resistance can be obtained. Specifically, 2- (3-methylbutyl) benzimidazole, 2- (3-methylbutyl) tosylimidazole, and 2- (3-methylbutyl) xylylimidazole are preferable as the active ingredient of the metal surface treatment agent of the present invention. It is illustrated as. To apply the surface treatment agent of the present invention to a metal surface or the surface of a printed wiring board, a method of dipping or spraying is used.

[0005]

According to the above-mentioned preflux processing method,
It is possible to manufacture a printed wiring board which has good spreadability and wettability of cream solder, a solder rising rate after reflow, and wettability, and is excellent in terms of working environment and safety.

[0006]

EXAMPLE A 1% solution containing 2- (3-methylbutyl) benzimidazole as an active ingredient was placed in a 5 liter container,
The liquid temperature was adjusted to 40 ° C. by heating. On the other hand, 1 cm x 5 cm
× 0.3mm copper plate and 20cm × 24cm × 1.6m
The through-hole substrate of m was degreased, washed with water, soft-etched, washed with water, pickled, washed with water to prepare a sample piece, which was added to a 1% solution containing 2- (3-methylbutyl) benzimidazole as an active ingredient. Soaked for a second. After that, it was washed with water, put in a hot air drier and heated at 120 ° C. for 5 minutes, then put in a hot air drier and heated at 200 ° C. for 15 minutes, and brushed with post flux before measurement to measure the solder rise of through holes. .. The sample was placed in a hot air drier and heated at 200 ° C. for 15 minutes, dipped in post flux before measurement, and the wetting time was measured using a solder wettability tester. The test piece after the moisture resistance (90% RH / 40 ° C./96 hr) treatment was dipped in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 1.

[0007]

EXAMPLE A 1% solution containing 2- (3-methylbutyl) tosylimidazole as an active ingredient was placed in a 5 liter container,
The liquid temperature was adjusted to 40 ° C. by heating. On the other hand, 1 cm x 5 cm
× 0.3mm copper plate and 20cm × 24cm × 1.6m
Prepare the test piece by degreasing, washing with water, soft etching, washing with water, pickling, washing with water on the through-hole substrate of m.
It was immersed for 60 seconds in a 1% solution containing 2- (3-methylbutyl) tosylimidazole as an active ingredient. After that, it was washed with water and then put in a hot air drier and heated at 120 ° C. for 5 minutes, then put in a hot air drier and heated at 200 ° C. for 15 minutes, and brushed with post flux before measurement to measure the solder rise of through holes. .. Put in a hot air dryer at 200 ° C for 1
It was heated for 5 minutes, immersed in post flux before measurement, and the wetting time was measured using a solder wettability tester. Moisture resistance (9
The test piece after the treatment of 0% RH / 40 ° C./96 hr) was dipped in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 1.

[0008]

Example A 1% solution containing 2- (3-methylbutyl) xylylimidazole as an active ingredient was placed in a 5 liter container and the liquid temperature was adjusted to 40 ° C. On the other hand, 1 cm x 5
cm × 0.3 mm copper plate and 20 cm × 24 cm × 1.
A 6 mm through-hole substrate was degreased, washed with water, soft-etched, washed with water, pickled, washed with water to prepare a test piece, and prepared into a 1% solution containing 2- (3-methylbutyl) xylylimidazole as an active ingredient. It was immersed for 60 seconds. After that, it was washed with water, put in a hot air drier and heated at 120 ° C. for 5 minutes, then put in a hot air drier and heated at 200 ° C. for 15 minutes, and brushed with post flux before measurement to measure the solder rise of through holes. .. Put in a hot air dryer, 200 ℃
The sample was heated for 15 minutes in the above and was immersed in post flux before measurement, and the wetting time was measured using a solder wettability tester. The test piece after the treatment against humidity (90% RH / 40 ° C./96 hr) was immersed in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 1.

[0009]

EXAMPLE A 1% mixed solution containing 2- (3-methylbutyl) benzimidazole and 2- (3-methylbutyl) tosylimidazole as active ingredients was placed in a 5 liter container and heated to a liquid temperature of 40 ° C. for adjustment. On the other hand, 1 cm x 5 cm x
0.3 mm copper plate and 20 cm x 24 cm x 1.6 mm
The through-hole substrate was degreased, washed with water, soft-etched, washed with water, pickled, washed with water to prepare a test piece, and the above-mentioned 2- (3-methylbutyl) benzimidazole, 2-
It is immersed in a 1% mixed solution of (3-methylbutyl) tosylimidazole for 60 seconds, then washed with water, put in a hot air dryer and heated at 120 ° C for 5 minutes, and then put in a hot air dryer and heated at 200 ° C for 15 minutes. Before the measurement, a post flux was applied with a brush to measure the solder rise of the through hole.
The sample was placed in a hot air dryer, heated at 200 ° C. for 15 minutes, immersed in post flux before measurement, and the wetting time was measured using a solder wettability tester. Moisture resistance (90% RH / 40 ° C / 9
6 hr) The treated test piece was immersed in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 1.

[0010]

The pre-flux of the present invention has a coating film formed on the surface of copper or a copper alloy, which has excellent heat resistance, spreads cream solder well even after being exposed to high temperature, has good wettability, and has excellent reflow solderability. This is particularly effective in terms of good solderability and wettability, and in terms of working environment and safety, in surface mounting electronic components on a printed wiring board.

[Table 1]

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[Procedure amendment]

[Submission date] September 22, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Method for surface treatment of metal

[Claims]

[Chemical 1]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal rust preventive treatment, and is suitable as a heat-resistant preflux for preventing a metal exposed portion of a printed wiring board from rusting and improving solderability. Also, solder, electroless solder, nickel
Rust prevention of gold, silver, zinc, etc., connector pinholes, no
Also suitable as a sealing agent with lubricity for electrolytic solder, etc.
It is something.

[0002]

2. Description of the Related Art Preflux, which has been conventionally used for the purpose of preventing corrosion of a circuit portion made of copper or a copper alloy of a printed wiring board and maintaining solderability, is roughly classified into a rosin that coats the entire printed wiring board. System preflux,
There are two types of alkylimidazole-based preflux that selectively chemically react with copper or a copper alloy. For the former, apply natural rosin, rosin ester, rosin-modified maleic acid resin, etc. dissolved in an organic solvent with a roll coater, or spray or dip it on the entire printed wiring board and dry to form a film. Used in the method. Therefore, there is a drawback that the working environment and safety are significantly impaired by the volatilization of the organic solvent. In addition, since rosin-based preflux uses a volatile solvent, it also has a drawback that it may be accompanied by danger of ignition during work. On the other hand, the alkyl imidazole pre-flux is water-soluble and is excellent in terms of working environment and safety, but when the chemically reacted alkyl imidazole copper complex is exposed to high temperature, it is a catalyst of oxygen and copper in the air. It deteriorates by the action and inhibits the action of postflux,
It has the drawback of deteriorating the solderability.

[0003]

Recently, a surface mounting method has been widely adopted as a method for soldering an electronic component to a printed wiring board. Due to this surface mounting method, reflow of solder paste solder for electronic parts, and the like, the printed wiring board is more often exposed to high temperatures, and the heat resistance of the pre-flux used to maintain the solderability of the printed wiring board, That is, the pre-flux performance is required to have excellent solderability after the printed wiring board is exposed to high temperature. Further, development of a preflux which does not use a volatile solvent having a problem in air pollution and has excellent solderability even after being exposed to a high temperature has been earnestly desired.

[0004]

In view of such circumstances, the present inventors have made earnest studies on a preflux which does not use a volatile solvent and has good solderability even after being exposed to a high temperature. As a result, acetic acid, iodoacetic acid, bromoacetic acid , paranitrobenzoic acid, paratoluenesulfonic acid, picric acid, oxalic acid, formic acid, succinic acid, phosphorous acid, maleic acid, acrylic acid, fumaric acid, tartaric acid, adipic acid, lactic acid, Organic acids such as oleic acid , inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid , or zinc acetate, lead acetate, zinc hydroxide, lead hydroxide, zinc bromide, zinc phosphate, zinc oxide, zinc chloride, ferrous chloride , Ferric chloride, cuprous bromide, cupric bromide, cuprous iodide, ants
Copper acid , nickel chloride, cuprous chloride, cupric chloride, cuprous oxide, cupric oxide, copper hydroxide, copper phosphate, copper carbonate, copper acetate, a solution containing a metal compound such as copper sulfate, Or at least one liquid selected from the group consisting of water-soluble solvents such as methanol, ethanol, isopropyl alcohol, butanol, and acetone, and one or more kinds of the compound represented by (Chemical formula 1) as an active ingredient. The present invention has been completed by finding that the above-mentioned conventional problems can be solved and the intended purpose can be achieved when a solution obtained by mixing the above is used as a metal surface treatment agent. As the above-mentioned organic acid or the like used for solubilizing or emulsifying the compound represented by (Chemical Formula 1), an organic acid, a salt of an organic acid, or a water-soluble solvent such as alcohol can be used alone, respectively. It is also possible to mix and use it at an arbitrary ratio. For example, the water-soluble solvent may be used alone or in combination with an organic acid or the like. Particularly, when the organic acid or the like is used alone, 2- (3-methylbutyl) benzimidazole, 2
-(3-Methylbutyl) methylbenzimidazole , 2
When it becomes difficult to dissolve-(3-methylbutyl) dimethylbenzimidazole or a derivative thereof, it is preferable to add a water-soluble solvent, and in this case, the content is appropriately 0 to 60%. There are many. The solution obtained by dissolving each of the above-mentioned solvents contains 0 parts of the above-mentioned active ingredient.
The method of immersing in a solubilizing solution containing 0.1 to 10%, preferably 0.5 to 5%, or an emulsifying solution is generally used. Immersion is performed in a temperature range of 0 to 100 ° C. and immersion time is several seconds to several seconds. Sufficient treatment is appropriate. Also after the conversion coating formation, complex
Body formation treatment Infrared / near-infrared / far-infrared / ultraviolet irradiation treatment is suitable at a temperature range of 0 to 300 ° C. for a treatment time of several seconds to several tens of minutes. Exposure treatment of ozone O ₃ for several seconds to several tens of minutes is appropriate. It is suitable to carry out chemical treatment such as immersion and spraying for several seconds to several tens of minutes in a concentration range of hydrogen peroxide water of 1 to 20%. By performing the treatments 1 to 3, a chemical conversion coating having excellent heat resistance can be obtained. Specific examples of the active ingredient of the metal surface treating agent of the present invention include 2- (3-methylbutyl) benzimidazole, 2- (3-methyldutyl) methylbenzimidazole , and 2- (3-methylbutyl) dimethylbenzene.
'S imidazole is preferably exemplified. To apply the surface treatment agent of the present invention to a metal surface or the surface of a printed wiring board, a method of dipping or spraying is used.

[0005]

[Action] more heat to the processing method of the pre-fluxes above
An excellent rust preventive film is formed, and cream solder after reflow
It is possible to manufacture a printed wiring board which has good spreadability , solderability and wettability, and is excellent in terms of working environment and safety.

[0006]

EXAMPLE A solution containing 1% of 2- (3-methylbutyl) benzimidazole , formic acid, ammonia and cupric chloride was mixed with 5 %.
It was put in a liter container and the liquid temperature was adjusted to 40 ° C by heating. On the other hand, 1 cm x 5 cm x 0.3 mm copper plate and 20
cm × 24 cm × 1.6 mm through-hole substrate was degreased, washed with water, soft etching, washed with water, pickled, washed with water to prepare a sample piece, and the 2- (3-methylbutyl) benzimidazole was used as an active ingredient. 6 in 1% solution
It was immersed for 0 seconds. Then, rinse with water, put in a hot air dryer, heat at 120 ° C for 5 minutes, and put in a hot air dryer. 2
It was heated at 00 ° C. for 15 minutes and brushed with post flux before measurement to measure the solder buildup of the through hole. The sample was placed in a hot air drier and heated at 200 ° C. for 15 minutes, dipped in post flux before measurement, and the wetting time was measured using a solder wettability tester. Moisture resistance (90% RH / 40 ° C / 96h
r) The treated test piece was dipped in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 1.

[Table 1]

[0007]

EXAMPLE A solution containing 2- (3-methylbutyl) methylbenzimidazole 1%, formic acid, ammonia and cupric chloride was placed in a 5 liter container and the temperature of the solution was adjusted to 40 ° C. It was heated and adjusted. On the other hand, 1 cm x 5 cm x 0.3 mm copper plate and 2
A 0 cm × 24 cm × 1.6 mm through-hole substrate is degreased, washed with water, soft etching, washed with water, pickled, washed with water to prepare a test piece, and the 2- (3-methylbutyl) methylbenzimidazole is used as an active ingredient. It was immersed in a 1% solution for 60 seconds. After that, it was washed with water and then put in a hot air drier and heated at 120 ° C. for 5 minutes, then put in a hot air drier and heated at 200 ° C. for 15 minutes, and brushed with post flux before measurement to measure the solder rise of through holes. ..
The sample was placed in a hot air drier and heated at 200 ° C. for 15 minutes, dipped in post flux before measurement, and the wetting time was measured using a solder wettability tester. Moisture resistance (90% RH / 40 ° C / 9
6 hr) The treated test piece was immersed in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 2.

[Table 2]

[0008]

EXAMPLE A solution containing 2- (31-methylbutyl) dimethylbenzimidazole 1%, formic acid, ammonia and cupric chloride was placed in a 5 liter container and the temperature of the solution was adjusted to 40 ° C. It was heated and adjusted. On the other hand, a 1 cm × 5 cm × 0.3 mm copper plate and a 20 cm × 24 cm × 1.6 mm through-hole substrate are degreased, washed with water, soft-etched, washed with water, pickled, washed with water to prepare a test piece and prepare the above-mentioned 2 1% containing-(3-methylbutyl) dimethylbenzimidazole as an active ingredient
It was immersed in the solution for 60 seconds. After that, it was washed with water and then put in a hot air drier and heated at 120 ° C. for 5 minutes, then put in a hot air drier and heated at 200 ° C. for 15 minutes, and brushed with post flux before measurement to measure the solder rise of through holes. .. The sample was placed in a hot air drier and heated at 200 ° C. for 15 minutes, dipped in post flux before measurement, and the wetting time was measured using a solder wettability tester. Against humidity (90% RH / 40 ℃
/ 96 hr) The test piece after the treatment was immersed in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 3.

[Table 3]

[0009]

EXAMPLES 2- (3-methylbutyl) benzimidazole 0.5%, 2- (3-methylbutyl) Mechirubenzu Lee <br/> imidazole 0.5%, formic acid, ammonia, cupric chloride
Put the mixed solution containing it into a 5 liter container and keep the liquid temperature at 40 ° C.
It was heated and adjusted. On the other hand, 1 cm x 5 cm x 0.3 mm
The copper plate and the through-hole substrate of 20 cm × 24 cm × 1.6 mm are degreased, washed with water, soft-etched, washed with water, pickled, washed with water to prepare a test piece, and the 2- (3-methylbutyl) benzimidazole is prepared. 60% in a 1% mixed solution of 2- (3-methylbutyl) methylbenzimidazole
Immerse for 2 seconds, then rinse with water and place in a hot air dryer 1
After heating at 20 ° C for 5 minutes, put in a hot air dryer to 200 ° C
After heating for 15 minutes, brushing was applied with post flux before measurement, and the solder buildup of the through hole was measured. The sample was placed in a hot air dryer, heated at 200 ° C. for 15 minutes, immersed in post flux before measurement, and the wetting time was measured using a solder wettability tester. Moisture resistant (90% RH / 40 ° C / 96hr)
The treated test piece was dipped in post flux and the wetting time was measured using a solder wettability tester. The test results are shown in Table 4.

[Table 4]

[0010]

EFFECTS OF THE INVENTION The coating formed on the surface of a metal with the pre-flux of the present invention is excellent in rust prevention and heat resistance, spreads cream solder even after being exposed to high temperature, has good wettability, and has excellent reflow solderability. With the effect of good solderability and wettability,
In addition, in terms of working environment and safety, it is possible to exert a particularly remarkable effect in surface-mounting electronic components on a printed wiring board.

Claims (2)

[Claims] 1. A method for surface treatment of a metal, which comprises performing surface treatment with a preflux solution containing a salt of the compound represented by (Chemical formula 1) or a derivative thereof. [Chemical 1] 2. A method for treating a metal, which comprises performing a surface treatment with a pre-flux solution containing a salt of a compound represented by (Chemical formula 1) or a derivative thereof, and then performing an oxidation treatment.