JPH07243091A - Electrolytic treatment of metal surface - Google Patents

Abstract

PURPOSE:To form a coating film excellent in moisture, heat and chemical resistances on a metal surface and to improve wettability with solder by electrolyzing the metal surface in an aq. soln. contg. a specified perimidine compd. as an effective component. CONSTITUTION:The metal surface of a copper plate, etc., is electrolyzed as the cathode or anode by a PR method, an AC method, a DC method, an AC-DC superposing method or a method using AC in combination in an aq. soln. contg. a perimidine compd. represented by one of formulae I-V or its deriv. as an effective component or further contg. an org. acid, a metallic compd., ammonium salts, etc. In the formulae I-V, R1 is H, alkyl, phenylalkyl or allyl, R2 is H, alkyl, phenylalkyl or alkylphenyl, R3 is H, sulfonic acid, alkyl or halogen, (n) is 0-17 and (x) is 0-1. A water-soluble preflux contg. the perimidine compd. is applied to the metal surface and soldering is carried out. after the surface treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to anticorrosion and solder roughening of metals such as copper, copper alloys, solders, electroless solders, zinc, nickel, gold, silver, rhodium, palladium, ruthenium and their alloys. The present invention relates to a treatment method for improving discoloration prevention, alkali resistance, moisture resistance, chemical resistance, heat resistance, and solderability, and particularly for maintaining the solderability of these metals in a good state for a long period of time, and for printed wiring. It is intended to provide a method suitable for preventing surface roughness due to an alkaline solution during plate production. Also, since both dissimilar metals joined can be treated, it is also ideal for rust prevention of plating pinholes, and rustproofing of electroless solder pinholes,
It is suitable as a sealing agent for nickel / gold plating of connectors. It is also suitable as a printed wiring board for connection of chips and packages of high-density surface mounting electronic components. Also, solder heat treatment of solder powder,
It is suitable for manufacturing a copper through-hole printed wiring board treated with an alkaline etching solution.

[0002]

2. Description of the Related Art Alkylimidazole-based preflux, which has been used for the purpose of preventing rust on a circuit portion made of copper or a copper alloy of a printed wiring board and maintaining solderability, is water-soluble and has a It is excellent both in terms of safety and safety, but when the chemically reacted alkyl imidazole copper complex is exposed to high temperatures, it deteriorates due to the catalytic action of oxygen and copper in the air, inhibiting the action of post-flux and soldering. It has the drawback of deteriorating the sex. The method of manufacturing a printed wiring board by the pattern plating method is to drill a hole in a copper clad laminate, chemically copper plating, electrolytic copper plating, and then an alkaline development type photosensitive film soluble in an alkaline aqueous solution, and a negative circuit on the copper clad laminate. After forming, and then electrolytic copper plating and soldering, contact with an alkaline aqueous solution to remove the alkali developing type photosensitive film. At this time, the surface of the solder may be attacked by the alkali and the copper material may be exposed. In this case, the circuit may be cut by etching copper with an alkaline etching solution in a later step. Further, when a solder through-hole substrate is manufactured with the solder plating left, the solderability is poor as it is, and it is necessary to perform a fusing treatment or the like.
Electroless soldering, which is one of the solder joining techniques for printed wiring boards, is performed by displacement plating. Therefore, it becomes porous and the copper surface of the material is exposed. In addition, precipitation is a mixture of both lead and tin, which are performed separately. For this reason, copper and tin alloys having poor solderability are likely to be generated, and lead and tin are likely to be oxidized, so that good solderability cannot be maintained for a long period unless fusing after plating. Nickel easily forms a strong oxide film and has poor solderability. Therefore, in printed wiring boards and connectors, nickel is plated with gold to prevent oxidation when solderability is required. Money,
Chromate treatment is used for rust prevention of silver and zinc,
There is a problem because a harmful hexavalent chromium compound is used. Further, for rust prevention of silver, paraffin or the like is dissolved in a solvent and applied, but there is a problem in using the solvent.

[0003]

In recent years, the surface mounting method has been widely adopted as a method for soldering electronic components to a printed wiring board. Due to this surface mounting method, reflow of low melting point cream solder for temporary fixing of electronic parts, the printed wiring board is exposed to high temperatures frequently, and the heat resistance of the pre-flux used to maintain the solderability of the printed wiring board. Of the low melting point cream solder after the printed wiring board is exposed to a high temperature, the wettability, spreadability and solderability of the low melting point solder paste are required to be excellent in the performance of the preflux. In the manufacturing method of a printed wiring board, the reliability as a solder etching resist film is poor and manufacturing defects are likely to occur.Therefore, when the alkali development type photosensitive film is peeled off, solder roughening during alkali etching is prevented and good circuit formation is achieved. While maintaining good solderability. Further, in the electroless solder, not only thermal stress to the substrate is strong but also costly fusing is not performed, but good solderability is maintained by rust preventive treatment. Nickel does not use expensive gold plating to prevent discoloration and maintain good solderability. Silver,
Zinc is treated with a safe solution containing no harmful hexavalent chromium compound to prevent discoloration for a long period of time and maintain good solderability. Also, the sealing treatment maintains the corrosion resistance of the connector terminals. In the method of manufacturing a printed wiring board, the deviation during cream solder printing, the solder film thickness, the productivity, the cost, etc. are poor. Therefore, it is earnestly desired to develop a solder substrate that is excellent in the uniformity of the solder film thickness and in the control of the film thickness after the solder powder is adhered and the reflow treatment is performed after selectively reacting the adhesive chemical conversion film only on the exposed metal parts. ing.

[0004]

In view of such circumstances, the present inventors have found that the low melting point cream solder has wettability and spreadability even after being exposed to a high temperature. Solderability after reflow,
Heat-resistant water-soluble pre-flux agent with good wettability. Also, a solder rust preventive and an electroless solder rust preventive to prevent solder roughening and discoloration during alkaline etching when peeling an alkaline development type photosensitive film. In addition, it is a rust preventive agent with excellent rust prevention, moisture resistance, heat resistance, and solderability for connector parts and nickel substrates. Also, an adhesive that selectively reacts the adhesive film only on the exposed portion of the metal to attach the metal powder. In addition, as a result of extensive studies on a surface protective agent that forms a chemical conversion film on a circuit portion of copper and resists an alkaline etching solution, as an organic acid used in the practice of the present invention, acetic acid, iodoacetic acid, bromoacetic acid, dimethylacetic acid , Diethyl acetic acid, α-bromoacetic acid,
Organic acids such as para-nitrobenzoic acid, para-toluenesulfonic acid, picric acid, oxalic acid, formic acid, succinic acid, maleic acid, acrylic acid, fumaric acid, tartaric acid, adipic acid, lactic acid, oleic acid, citric acid, metasulfonic acid, sulfamic acid, etc. , Inorganic acids such as hydrochloric acid, sulfuric acid, phosphorous acid, phosphoric acid, and other carboxylic acids, halogenated fatty acids, halogenated aromatic carboxylic acids, etc., and they may be added in a proportion of 0.01 to 20% with respect to water. . One or more compounds represented by (Chemical formula 1) to (Chemical formula 5) may be added as an active ingredient at a ratio of 0.1 to 5% with respect to the acid aqueous solution. Typical compounds used as metal ions in the practice of the method of the present invention include lithium, beryllium, potassium, magnesium, zinc acetate, zinc formate, zinc lactate, zinc counate, zinc benzoate, zinc oxalate, and water. Zinc oxide, zinc bromide, zinc phosphate, zinc oxide, zinc chloride, lead acetate, lead hydroxide, lead bromide, lead iodide, lead oxalate, lead borate, ferrous chloride, ferric chloride, bromide Cuprous, cupric bromide, cuprous iodide, copper formate, nickel chloride, nickel acetate, cuprous chloride, cupric chloride, cuprous oxide, cupric oxide, copper hydroxide,
It is a metal compound such as copper phosphate, copper carbonate, copper acetate, and copper sulfate, and may be added in a proportion of 0.001 to 5% with respect to water. The halogenated aromatic carboxylic acid used in the practice of the present invention includes 3-bromo-4methylbenzoic acid,
4- (bromomethyl) phenylacetic acid, α-bromophenylacetic acid, α-bromotetradecanoic acid, 2-bromophenylacetic acid, 3-bromophenylacetic acid, 4-bromophenylacetic acid, etc., and 0.01 to 20 with respect to the aqueous solution. %, Preferably 0.1 to 5%.
Examples of the halogenated fatty acid used in the practice of the present invention include bromoacetic acid and 3-bromo-2- (bromomethyl).
Propionic acid, 2-bromobutanoic acid, 4-bromobutanoic acid, 2-bromohexanedecanoic acid, 2-bromohexanoic acid, 2-bromo-3-methylbutanoic acid, 2-bromo2-
Methylpropionic acid, 2-bromooctanoic acid, 8-bromooctanoic acid, 2-bromopropionic acid, 3-bromopropionic acid, 2-bromopentanoic acid, 5-bromopentanoic acid, chloroacetic acid, chlorobutyric acid, chloropropionic acid, etc. Therefore, it may be added in the range of 0.01 to 20%, preferably 0.1 to 5% with respect to the aqueous solution. In the practice of the present invention, when it becomes difficult to dissolve the compound represented by (Chemical formula 1) to (Chemical formula 5) and the organic acid, the metal compound, the halogenated aromatic carboxylic acid, or the halogenated fatty acid, methanol or ethanol is used. Water-soluble solvents such as isopropyl alcohol, butanol, and acetone can be used alone, or can be used by mixing them at an arbitrary ratio. For example, the above water-soluble solvent may be used alone or in combination with other organic acids, etc. In particular, when the organic acid alone is used, it is difficult to dissolve the compound represented by (Chemical formula 1) to (Chemical formula 5) or its derivative. In this case, it is preferable to add a water-soluble solvent, and the content ratio in this case is 0.01 to
In many cases, 60% is appropriate. In the emulsifying dispersant, humic acid, nitrohumic acid and the like are used, and are in the range of 0.01 to 20%, preferably 0.
It may be added at a rate of 1 to 5%. Representative of the compounds as barium ions used in the practice of the method of the invention are barium acetate, barium bromide, barium chloride, barium fluoride, barium carbonate, barium hydroxide, barium nitrate, barium phosphate, barium oxide. , Barium oxalate, etc., and the barium ion concentration is 30 ppm or more, preferably 200 to 5000 pp with respect to the treatment liquid.
It may be added at a ratio of m. When barium ions and halogen ions coexist, compounds used as a halogen ion source are sodium chloride, potassium chloride, sodium iodide, sodium fluoride, potassium fluoride,
Alkali metal such as barium chloride, barium bromide, barium chloride, ammonium chloride, ammonium bromide, and ammonium ion, halides, hydrochloric acid, hydrohalic acid such as hydrobromic acid, chromium chloride, zinc chloride, bromide It is a metal halide such as zinc, lead chloride, nickel chloride, nickel bromide, cuprous bromide, cupric bromide, copper iodide, cupric chloride, etc. Is 30 ppm or more, preferably 200 to 5000 ppm
It may be added in the ratio of. Further, it is effective to add a surfactant and an emulsifying dispersant. It should be noted that adding a substance having a buffering action such as aqueous ammonia or amines to the treatment liquid is effective not only for enhancing the stability of PH of the aqueous solution but also for accelerating the film formation rate. By carrying out electrolytic treatment in the aqueous solution containing the compounds represented by (Chemical formula 1) to (Chemical formula 5) and the organic acid, the metal compound and about 30 ppm or more of barium ion and halogen ion used in the method of the present invention. The heat resistance, solder wettability, and solder spreadability of the chemical conversion film can be further enhanced. In order to apply a rust-proof chemical conversion coating film, a tackifying film formation, and a chemical resistance chemical conversion coating film to the metal surface with the metal surface treatment agent of the present invention, electrolytic treatment is carried out while bringing the metal surface into contact with a treatment liquid. Also,
When ultrasonic waves or electromagnetic waves are irradiated while the metal surface is in contact with the treatment liquid, it effectively penetrates into the inside of the holes. It is suitable that the temperature of the treatment liquid to be brought into contact is in the temperature range of 0 to 100 ° C. and the immersion time is several seconds to several tens of minutes. The electrolytic treatment is
Current density of 0.01 A / dm ² to 10 at cathode or anode
In the A / dm ² range, it is suitable that the immersion time is several seconds to several tens of minutes. In addition, as a treatment for further improving the moisture resistance and the chemical resistance after forming the rust preventive conversion film, infrared / near-infrared / far-infrared / ultraviolet irradiation treatment is performed in a temperature range of 0 to 300 ° C.
Treatment time of several seconds to several tens of minutes is effective. The method for synthesizing the compounds represented by (Chemical formula 1) to (Chemical formula 5) used in the practice of the method of the present invention can easily be carried out by removing impurities after the amine and the fatty acid are reacted by heating.
A compound represented by (Chemical Formula 5) can be obtained. The use of the compounds represented by (Chemical formula 1) to (Chemical formula 5) used in carrying out the method of the present invention is not particularly limited, but in addition to a metal surface treatment agent, a curing agent for an epoxy resin, a dyeing aid, It is useful as a photosensitizer and an organic synthetic intermediate.

[0005]

According to the above-mentioned treatment method, (Chemical formula 1) to (Chemical formula 5) effective for rust prevention are applied to metal surfaces such as copper, copper alloy, solder, electroless solder, nickel, gold, silver and zinc. A rust preventive conversion film, an adhesive conversion film, and a chemical resistance conversion film which are the main components are formed. These chemical conversion coatings are water repellent, moisture resistant, heat resistant,
It has excellent chemical resistance, protects the metal surface for a long time, and has good wettability and spreadability of low melting point cream solder, solderability after reflow, and wettability. Further, the uniformity of the solder film thickness after the solder powder is adhered to the adhesive chemical conversion film and the reflow treatment is performed is good. Further, a chemical resistant chemical conversion film is formed on a required copper circuit portion and then treated with an alkali etching solution, whereby the production of a copper through-hole wiring board is good. In addition, it is possible to manufacture a printed wiring board excellent in terms of work environment and safety. Also, by performing electrolytic treatment and ultrasonic treatment, a dense film can be formed in a short time.

[0006]

EXAMPLES Compounds represented by (Chemical formula 1) to (Chemical formula 5) (Table 1
0.5%), succinic acid, carboxylic acid,
An aqueous solution of each type containing aqueous ammonia, cupric chloride, ion-exchanged water, or an emulsified aqueous solution was prepared, placed in a 100 ml container, and the liquid temperature was adjusted to 40 ° C. On the other hand, 1 cm
A copper plate of 5 cm x 5 mm was plated with copper sulfate, electroless copper, electric solder, electroless solder, nickel and silver. Then, degreasing, washing with water, soft etching, washing with water, pickling, washing with water to wash the surface, and in each kind of 0.5% aqueous solution containing the compound represented by the above (Chemical formula 1) to (Chemical formula 5) as an active ingredient. At the cathode 1
A / dm ^{2 was} electrolyzed for 1 minute and the anode had a resistance of 0.
Electrolysis treatment was carried out for 5 minutes at 5 A / dm ² . After that, it is washed with water to prepare a test piece of (1), and then the test piece of (1) is put in a hot air dryer and heated at 200 ° C. for 5 minutes and immersed in post flux before measurement using a solder wettability tester. And the wetting time was measured. (2) After applying the rosin-based pre-flux to the test piece, put the sample piece in a hot air dryer for 5 minutes at 200 ° C., immerse in the post flux before measurement, and use a solder wettability tester. And the wetting time was measured. Moisture resistance (MIL-S
TD-202F-M-106E), the test piece was immersed in post flux and the wetting time was measured using a solder wettability tester. (4) The alkaline solution and the alkaline etching solution were heated to 40 ° C., and the test piece was immersed for 5 minutes. After that, wash with water and check the surface condition (roughness, discoloration). The gas corrosion test (1
The surface condition (roughness, discoloration) of the metal after ± 0.3 ppm H ₂ S, 25 ± 2 ° C., 5% RH, 10 days) is observed.
Solder powder is applied to the test pieces of (6) to check the adhesiveness and the uniformity of the film after reflow. The test results are shown in Table 1.
It was shown to.

[Table 1]

[0007]

According to the treatment method of the present invention, a chemical conversion rust-preventive coating excellent in moisture resistance, heat resistance and chemical resistance is formed on a metal surface,
Adhesive chemical conversion coating and chemical resistant chemical conversion coating are formed, and it has the effect of good wettability and spreadability of low melting point cream solder, and solderability after reflow and good wettability. It is possible to exert a remarkable effect. In addition, the pattern plating method not only prevents the solder from becoming rough when processing alkaline aqueous solutions during the manufacture of printed wiring boards and eliminates the risk of circuit disconnection, but also leaves solder at the soldering part and improves solderability without fusing treatment. It can be kept in a state. It is also suitable as a sealing agent for nickel / gold plating of connectors. It is also suitable as a printed wiring board for connection of chips and packages of high-density surface mounting electronic components. Further, it is suitable for producing a solder through heat treatment of solder powder and a copper through hole printed wiring board treated with an alkaline etching solution. In addition, the adhesive chemical conversion coating has excellent rust prevention, heat resistance, good adhesion of solder powder, excellent solder spreadability after reflow, wettability and uniformity, and excellent printing in terms of work environment and safety. It is possible to manufacture wiring boards and metal parts.

Claims (10)

[Claims] 1. A metal surface is used as a cathode or an anode in an aqueous solution containing a compound represented by (Chemical formula 1) to (Chemical formula 5), and P
A surface treatment method for a metal, which comprises electrolyzing by an R method, an AC method, a DC method, an AC / DC superposition method, or an AC combined method. [Chemical 1] [Chemical 2] [Chemical 3] [Chemical 4] [Chemical 5] 2. A metal surface is used as a cathode or an anode in an aqueous solution containing a compound represented by (Chemical formula 1) to (Chemical formula 5) and an organic acid, a metal compound, or an ammonia salt, and a PR method, an AC method, a DC method, A surface treatment method for a metal, which comprises electrolyzing by an alternating current superposition method and an alternating current combined method. 3. A compound represented by (Chemical formula 1) to (Chemical formula 5), an organic acid, and a metal surface in an aqueous solution containing barium ions and halogen ions, with a metal surface serving as a cathode or an anode, a PR method, an AC method, a DC method, A surface treatment method for a metal, which comprises electrolyzing by an alternating current superposition method and an alternating current combined method. 4. A compound represented by (Chemical formula 1) to (Chemical formula 5), an organic acid, a metal compound, and a metal surface in an aqueous solution containing barium ions and halogen ions, the metal surface being used as a cathode or an anode, a PR method, an AC method, A surface treatment method for a metal, which comprises electrolyzing by a direct current method, an alternating current superposition method, an alternating current combined method. 5. A surface treatment method for a metal, which comprises applying a preflux such as a rosin-based preflux or a resin-based preflux after the surface treatment of the metal according to any one of claims 1 to 4. 6. A metal surface is coated with a water-soluble preflux containing a compound represented by (Chemical formula 1) to (Chemical formula 5) and an organic acid, a metal compound, an ammonia salt or the like. Alternatively, a surface treatment method for a metal, which comprises applying a pre-flux such as a rosin-based pre-flux or a resin-based pre-flux after applying the water-soluble pre-flux. 7. A method of manufacturing a printed wiring board, which comprises performing a soldering treatment after the surface treatment of the metal according to any one of claims 1 to 6. 8. After the surface treatment of the metal according to any one of claims 1 to 6, infrared reflow, near infrared reflow, far infrared reflow, nitrogen reflow, vapor reflow treatment of heating in air or a nitrogen atmosphere is performed. A method for manufacturing a characteristic printed wiring board. 9. After the surface treatment of the metal according to any one of claims 1 to 6, after applying solder powder or applying solder powder and applying post flux, infrared reflow, near infrared reflow, far A surface treatment method for a printed wiring board, which comprises performing heat treatment such as infrared reflow, nitrogen reflow, and vapor reflow treatment. 10. A method for manufacturing a printed wiring board, which comprises performing an alkaline solution treatment and an alkaline etching solution treatment after the surface treatment of the metal according to claim 1.