JP5473135B2 - Metal surface treatment agent - Google Patents

Description

  The present invention relates to a surface treating agent for metals, particularly silver or silver alloys.

  A connector that is a connecting part for electronic equipment is often made of a material in which a surface of brass or phosphor bronze is plated with copper or nickel and further silver-plated thereon. Since silver is a good conductor of electricity and heat, silver is used as a plating for connectors and lead frames as described above. However, the silver plating material is easily discolored in the air, and in particular, corrodes in an atmosphere containing sulfur and changes its color to brown or blue-black, resulting in poor electrical contact.

  One method for solving this problem is a surface treatment method. That is, the surface of the silver plating is treated with a treatment liquid to prevent deterioration in appearance and increase in contact resistance due to discoloration. As a conventional surface treatment method for a silver plating material, for example, as disclosed in Patent Document 1, a silver plating material is treated in a solution containing an inhibitor. In this method, although the effect of preventing discoloration due to corrosion of the silver plating is recognized, the effect of preventing the discoloration is not perfect, and there is a problem that the discoloration is still partly depending on the atmosphere.

  Further, Patent Document 2 discloses a surface treatment liquid and a surface treatment method for preventing discoloration due to corrosion of a silver plating material and further imparting lubricity to the plating surface. The surface treatment liquid contains one or more selected from the group consisting of a specific benzotriazole compound, mercaptobenzothiazole compound, and triazine compound as an inhibitor, and further contains a lubricant and an emulsifier. contains. Since the surface treatment liquid is not adjusted for pH, it is considered that the surface treatment is performed at pH 8.8 to 8.9. When used in a connector, it provides lubricity as well as preventing discoloration. However, the effect of preventing discoloration is not sufficient, and the heat resistance is not sufficient.

  Patent Document 5 discloses a nitrogen-containing heterocycle having a thione group or a mercapto group as a treatment method for improving the strength and corrosion resistance of a silver plating layer, particularly a silver plating layer formed by utilizing a silver mirror reaction. A method of treating with a treating solution containing an organic compound having a reaction or affinity with silver such as a compound is described. Further, the treatment solution contains sulfite, iodide or bromide at the same time, whereby the strength of the silver plating layer is improved and corrosion resistance with excellent stability is obtained. In Examples, a treatment solution containing the organic compound at a concentration of several g / L was used, and as a corrosion resistance evaluation, a small amount of acetic acid and cupric chloride were added to 5% by mass of saline. The sprayed aqueous solution was sprayed to evaluate peeling and haze, and there is no description regarding heat resistance.

A light emitting diode (LED) device is a diode that emits light by flowing a forward current through a semiconductor pn junction and recombining electrons and holes in the junction region, and has a simple structure and directly emits electric energy. Since it is converted into energy, conversion efficiency and reliability are high, and it has already been widely put into practical use.
In recent years, the use of white light-emitting diodes has attracted attention as a new light source and lighting fixture to replace incandescent and fluorescent lamps from the viewpoint of energy saving and environmental conservation.
This light-emitting diode device is designed such that a pedestal of a lead frame is processed, an LED chip is placed at a position surrounded by a reflective portion, and light emitted from the LED chip is efficiently extracted by the reflective portion. Further, the LED chip is sealed with a resin such as an epoxy resin as necessary.

This light-emitting diode device has been put into practical use as a light source, but has various problems to be improved. One of them is a problem of improving the reflectance of the reflecting portion.
Conventionally, silver, aluminum, or a gold film is known as a material having excellent light reflectance (Patent Documents 3 and 4). Among them, silver is known as the most suitable material as a reflecting material because of high glossiness and reflectance.

However, silver is active, and the surface of the silver film is easily discolored by oxidation or the like, affecting the light reflectivity of the silver film and degrading its performance. In particular, deterioration in light reflection performance becomes a problem due to discoloration caused by heat treatment in the LED manufacturing process and discoloration in a high temperature environment given at the time of use.
One method for solving this problem is a surface treatment method. However, conventional surface treatment agents do not have sufficient heat resistance of the resulting film, and even if the surface of the silver plating is processed, the film formed on the surface of the silver plating is decomposed when subjected to heat treatment, preventing discoloration, etc. However, there was a problem that the light reflection performance deteriorated.
No effective technology has been developed for the above-mentioned measures to improve the light reflection performance of the silver coating, or discoloration due to oxidation, particularly deterioration of light reflection performance due to discoloration in a high-temperature environment. There is a demand for such an improvement in order to contribute to the promotion of use as a white light source that requires high brightness for use in applications.
That is, there is a demand for a surface treating agent that has a high anti-discoloration effect even when exposed to a high temperature environment given during heat treatment in LED manufacturing processes or when used, has excellent wire bonding characteristics, and does not deteriorate reflectance due to surface treatment. ing.

JP-A-5-311492 Japanese Patent Laid-Open No. 9-249977 JP 2005-56941 A Japanese Patent Laid-Open No. 9-293904 JP 2004-169157 A

  The present invention is excellent in heat resistance, and has a high anti-discoloration effect even when exposed to a high temperature feeling environment given during heat treatment or use in LED manufacturing process, and forms a film on metal with excellent wire bonding characteristics. An object of the present invention is to provide a metal surface treatment agent that can be used and has no deterioration in reflectance due to surface treatment.

（式中、Ｒ₁は水素、置換又は無置換のアルキル基を表わし、Ｒ₂はアルカリ金属、水素、置換又は無置換のアルキル基を表わす。）

（式中、Ｒ₃はアルカリ金属又は水素を表わす。）

〔式中、Ｒ₄は−ＳＨ、アルキル基，アルケニル基又はアリール基で置換されたアミノ基、又はアルキル置換イミダゾリルアルキル、Ｒ₅、Ｒ₆は−ＮＨ₂、−ＳＨ又は−ＳＭ（Ｍはアルカリ金属を表わす）を表わす。〕
（２）更に界面活性剤を含有することを特徴とする前記（１）記載の耐熱性の高い皮膜を金属上に形成するための表面処理剤。
（３）前記金属が、銀または銀合金であることを特徴とする前記（１）又は（２）記載の耐熱性の高い皮膜を金属上に形成するための表面処理剤。
（４）ＬＥＤ反射材に用いることを特徴とする前記（１）〜（３）のいずれかに記載の耐熱性の高い皮膜を金属上に形成するための表面処理剤。
（５）前記（１）〜（３）のいずれかに記載の耐熱性の高い皮膜を金属上に形成するための表面処理剤を用いて処理されたことを特徴とする表面に皮膜が形成された金属を有する基材。
（６）前記基材がＬＥＤ反射材であることを特徴とする前記（５）記載の表面に皮膜が形成された金属を有する基材。 As a result of studies conducted by the inventor in order to solve the above problems, the inventors have invented the following surface treatment agent.
That is, the present invention
(1) A group consisting of a benzotriazole compound represented by the following general formula (1), a mercaptobenzothiazole compound represented by the following general formula (2), and a triazine compound represented by the following general formula (3) as an inhibitor 0.01 to 0.15 g / L of one or more compounds selected from 1 and 0.1 to 20 g / L of iodide and / or bromide are dissolved or dispersed in water, and the pH is adjusted to 4 A surface treating agent for forming a highly heat-resistant film on a metal, characterized in that it is prepared in -7.

(In the formula, R ₁ represents hydrogen, a substituted or unsubstituted alkyl group, and R ₂ represents an alkali metal, hydrogen, a substituted or unsubstituted alkyl group.)

(In the formula, R ₃ represents an alkali metal or hydrogen.)

[In the formula, R ₄ is —SH, an amino group substituted with an alkyl group, an alkenyl group or an aryl group, or an alkyl-substituted imidazolylalkyl; R ₅ , R ₆ are —NH ₂ , —SH or —SM (where M is an alkali Represents metal). ]
(2) A surface treatment agent for forming a highly heat-resistant film on the metal according to (1), further comprising a surfactant.
(3) The surface treatment agent for forming a highly heat-resistant film according to (1) or (2) above, wherein the metal is silver or a silver alloy.
(4) A surface treatment agent for forming a highly heat-resistant film on a metal according to any one of (1) to (3), which is used for an LED reflecting material.
(5) A film is formed on a surface, which is treated with a surface treatment agent for forming the highly heat-resistant film according to any one of (1) to (3) on a metal. A substrate having a metal.
(6) The base material having a metal with a film formed on the surface according to (5), wherein the base material is an LED reflecting material.

  The metal surface treated with the surface treatment agent of the present invention is excellent in heat resistance, has a high anti-discoloration effect even after heat treatment, has excellent wire bonding characteristics, and does not deteriorate reflectance due to the surface treatment. Further, the surface treatment agent of the present invention is water-soluble and does not contain an organic solvent or heavy metal, so that it is excellent in safety and does not cause unevenness in processing or poor appearance of spots. Further, the contact resistance is low and the solder wettability is also good.

  The inhibitor contained in the surface treatment agent of the present invention is selected from the following compounds, that is, benzotriazole compounds, mercaptobenzothiazole compounds, and triazine compounds. These inhibitors react with the metal to form a thin protective film on the metal surface, and the inside of the metal is protected by this film. As a result, the corrosion resistance (discoloration resistance) of the metal surface is improved.

（式中、Ｒ₁は水素、置換又は無置換のアルキル基を表わし、Ｒ₂はアルカリ金属、水素、置換又は無置換のアルキル基を表わす）
で表わされる。 The benzotriazole-based compound used in the present invention has the general formula (1)

(Wherein R ₁ represents hydrogen, a substituted or unsubstituted alkyl group, and R ₂ represents an alkali metal, hydrogen, a substituted or unsubstituted alkyl group)
It is represented by

The substituted or unsubstituted alkyl group represented by R ₁ in the general formula (1) is preferably an alkyl group having 1 to 24 carbon atoms, and the substituted or unsubstituted alkyl group represented by R ₂ is also represented by 1 to 24 carbon atoms. Are preferred. Examples of the alkyl group include a methyl group, an ethyl group, an octyl group, a hexadecyl group, and an octadecyl group. Moreover, as said substituent, an amino group, a mercapto group, a hydroxyl group etc. are preferable. The amino group may be substituted with an alkyl group having 1 to 24 carbon atoms.
Preferred examples of the compound represented by the general formula (1) include benzotriazole (both R ₁ and R ₂ are hydrogen), 1-methylbenzotriazole (R ₁ is hydrogen, R ₂ is methyl), tolyl Triazole (R ₁ is methyl, R ₂ is hydrogen), 1- (N, N-dioctylaminomethyl) benzotriazole (R ₁ is hydrogen, R ₂ is N, N-dioctylaminomethyl) and the like.

（式中、Ｒ₃はアルカリ金属又は水素を表わす）
で表わされる。
この一般式（２）で表わされる化合物のうち好ましいものを挙げると、例えばメルカプトベンゾチアゾール、メルカプトベンゾチアゾールのナトリウム塩、メルカプトベンゾチアゾールのカリウム塩などがある。一般式（２）においてＲ₃がアルカリ金属の場合メルカプトベンゾチアゾール系化合物の水への溶解が容易となる。 The mercaptobenzothiazole compound used in the present invention has the general formula (2)

(Wherein R ₃ represents an alkali metal or hydrogen)
It is represented by
Preferred examples of the compound represented by the general formula (2) include mercaptobenzothiazole, mercaptobenzothiazole sodium salt, mercaptobenzothiazole potassium salt, and the like. In the general formula (2), when R ₃ is an alkali metal, the mercaptobenzothiazole compound is easily dissolved in water.

〔式中、Ｒ₄は−ＳＨ、アルキル基，アルケニル基又はアリール基で置換されたアミノ基、又はアルキル置換イミダゾリルアルキル、Ｒ₅、Ｒ₆は−ＮＨ₂、−ＳＨ又は−ＳＭ（Ｍはアルカリ金属を表わす）を表わす〕
で表わされる。
一般式（３）中のＲ₄が表すアミノ基の置換基である前記アルキル基、又はアルケニル基としては炭素数１〜２４のアルキル基、アルケニル基が好ましく、アリール基としてはフェニル基が好ましい。 Triazine compounds are represented by the general formula (3)

[In the formula, R ₄ is —SH, an amino group substituted with an alkyl group, an alkenyl group or an aryl group, or an alkyl-substituted imidazolylalkyl; R ₅ , R ₆ are —NH ₂ , —SH or —SM (where M is an alkali Represents metal)
It is represented by
In the general formula (3), the alkyl group or alkenyl group which is a substituent of the amino group represented by R ₄ is preferably an alkyl group or alkenyl group having 1 to 24 carbon atoms, and the aryl group is preferably a phenyl group.

Preferred examples of the compound represented by the general formula (3) include the following.

Alternatively, there are alkali metal salts such as Na or K. In the general formula (3), when R ₅ and R ₆ are —SM, the triazine compound is easily dissolved in water.

  Inhibitors are dissolved or dispersed in water. The addition amount of the inhibitor is in the range of 0.01 to 0.15 g / L, preferably 0.01 to 0.1 g / L, more preferably 0.05 to 0.1 g / L. When the concentration of the inhibitor is less than 0.01 g / L, no treatment effect is observed, and when it exceeds 0.15 g / L, adverse effects are observed in contact resistance and wire bonding characteristics.

The surface treating agent of the present invention contains 0.1 to 20 g / L of iodide and / or bromide in total. The heat resistance is further improved by containing iodide and / or bromide. When the iodide and / or bromide content is less than 0.1 g / L, the heat resistance is not sufficiently improved. When the iodide and / or bromide content exceeds 20 g / L, there is a problem in solubility, and the surface treatment agent becomes turbid and reflective. The rate drops.
The content of iodide and / or bromide is preferably 0.1 to 10 g / L, more preferably 0.1 to 1 g / L.
As the iodide and bromide, it is preferable to use an iodide salt and a bromide salt in order to obtain an aqueous solution. As the iodide salt, potassium iodide, sodium iodide or the like can be used. As the bromide salt, potassium bromide, sodium bromide, ammonium bromide and the like can be used.

Pure water is preferably used, and the pH is adjusted to 4 to 7 after dissolving or dispersing the inhibitor. As the pH adjuster, it is preferable to use organic acids such as phosphoric acid, acetic acid, citric acid, tartaric acid, oxalic acid, malic acid, and succinic acid.
When the pH is low, the effect of preventing discoloration is increased, but the stability of the liquid is deteriorated. In addition, the solubility of the inhibitor also deteriorates. Conversely, when the pH is high, the stability of the liquid is improved, but the effect of preventing discoloration is lowered. From the discoloration preventing effect and the stability of the solution, the pH is 4 to 7, and more preferably 5 to 6.

Further, the surface treatment agent of the present invention may contain a surfactant for the purpose of dissolving the inhibitor in an aqueous solution, increasing the wettability of the metal surface to facilitate the penetration of the solution, and cleaning the metal surface. it can. In addition, the surface treatment agent of the present invention can contain a dissolution aid for the purpose of dissolving the inhibitor in an aqueous solution.
As the surfactant, a natural alcohol surfactant is preferable because it is excellent in biodegradability and has little adverse effect on the environment. Alkylphenol ethylene oxide adducts and higher alcohol ethylene oxide adducts, which are less decomposed by acid or alkali, can be preferably used.
As a solubilizing agent, ethylene glycol ethers such as methyl glycol, isopropyl glycol and butyl glycol, and propylene glycol ethers such as methyl propylene glycol, propyl propylene glycol and butyl propylene glycol can be preferably used.

Moreover, a pH buffer agent is mentioned as a component which may be further contained.
The pH buffer serves to keep the pH of the solution constant and to control the adsorptivity of the inhibitor. Examples of the pH buffer include sodium hydrogen phosphate, acetic acid, sodium acetate, citric acid, sodium citrate, tartaric acid, sodium tartrate and the like. In view of cost, ease of use, etc., citric acid, sodium acetate and the like are preferable.
The surface treating agent of the present invention does not contain a lubricant. In the case of a surface treatment agent used for connector applications that are connecting parts for electronic equipment, it is necessary to impart lubricity to the metal surface, and the lubricant is included, but this is not used for connectors but for LED reflectors, etc. The surface treating agent of the present invention does not need to be provided with lubricity, and does not contain a lubricant because it may adversely affect wire bonding characteristics.
In addition, the surface treatment agent of the present invention may not contain a polymer compound such as a butadiene / maleic anhydride copolymer because the resulting film becomes thick and may adversely affect wire bonding characteristics. preferable.

The treatment method may be any method such as immersing the material to be treated in the surface treatment agent, spraying or applying the surface treatment agent, but immersion is preferred. As immersion conditions, the immersion may be performed at a temperature of 15 to 60 ° C. for 5 seconds or longer, for example, 5 seconds to 1 minute, and then washed with water and dried.
Washing with water eliminates appearance defects such as uneven repair and spots.

  The material to be treated is a base material having a metal on the surface, and examples of the metal include silver, silver alloy, copper, brass, phosphor bronze, and iron. In particular, it can be suitably used as a surface treatment agent for silver and silver alloys that are easily discolored.

The surface treating agent of the present invention is an aqueous solution, and does not contain an organic solvent or heavy metal, and thus is excellent in safety. Moreover, the film obtained by the treatment with the surface treating agent of the present invention does not deteriorate even when heat treatment is performed, and the discoloration of silver can be suppressed even when a hydrogen sulfide gas test is performed after the heat treatment. The metal surface treated with the surface treatment agent of the present invention is not only excellent in anti-discoloration property after heat treatment at 200 ° C. for 1 hour and heat treatment at 120 ° C. for 6 hours, but also has low contact resistance and solder wettability. Good, excellent wire bonding characteristics, and no deterioration of reflectance due to surface treatment.
Therefore, it can be suitably used as a surface treatment agent for LED reflecting materials.

Hereinafter, the present invention will be described in detail with reference to examples.
Example 1
As a to-be-processed base material, what carried out silver plating of thickness of 4 micrometers on a pure copper substrate was used, and it surface-treated by being immersed in the surface treating agent of the composition shown below at 40 degreeC for 30 second.
Surface treatment agent composition Inhibitor: Triazine-2,4,6-trithiol 0.1 g / L
Potassium iodide: 0.1 g / L
Surfactant: oleyl alcohol ethoxylate 0.1 g / L
Dissolving aid; butyl propylene glycol 10g / L
pH buffer: Sodium hydrogen phosphate 10 g / L
Adjust to pH 5.5 using phosphoric acid as pH adjuster

The base material after the surface treatment of Example 1 was subjected to a hydrogen sulfide gas test (hydrogen sulfide concentration: 3 ppm, temperature: 40 ° C., humidity: 80% RH, test time: 4 hours) based on JIS 8502 without performing heat treatment. The appearance was visually observed. Further, after heat treatment at 200 ° C. for 1 hour with a hot air circulation dryer, the same hydrogen sulfide gas test was performed, and the appearance was visually observed.
Evaluation criteria ◎: No plating surface discoloration by visual observation ○: Discoloration of the plating surface to light yellow by visual observation △: Discoloration of the plating surface to light blue by visual observation ×: Plating by visual observation Table 1 shows the result of discoloration of the surface to a deep blue-black color.

Examples 2-12, Comparative Examples 1-18
Example 1 except that the inhibitor, potassium iodide or potassium bromide, and pH buffer in Example 1 were changed to the compounds and concentrations shown in Table 1 and the pH was changed to the values shown in Table 1 using phosphoric acid. Similarly, the surface treatment of the substrate to be treated was performed and evaluated in the same manner as in Example 1.
Although the base material which surface-treated with the surface treating agent of Examples 2-12 and Comparative Examples 2-18 did not show the discoloration of the silver surface after surface treatment, the surface treating agent of Comparative Example 1 is liquid. It was observed with the naked eye that the surface of the silver after the surface treatment was lightly turbid and turned pale yellow. Therefore, Comparative Example 1 was excluded from the evaluation of the hydrogen sulfide gas test.
The results are shown in Table 1.

Using the surface-treated substrates of Examples 1, 6, 11 and Comparative Example 10, contact resistance, solder wettability, wire bonding characteristics, and reflectance were evaluated as follows. The results are shown in Table 2.
(1) Contact resistance The contact resistance was measured with a direct current of 7.4 mA, an open-circuit voltage of 20 mV, and a load of 2.5 to 50 g. The criteria for determining contact resistance are as follows.
○: Contact resistance is less than 0.02Ω ×: Contact resistance is 0.02Ω or more (2) Solder wettability Solder wettability is 265 ° C tin-silver-copper alloy solder bath before and after heat treatment. The time required to reach 0 was measured and evaluated. The heat treatment was performed at 200 ° C. for 10 minutes. The criteria for determining solder wettability are as follows.
○: Time required for buoyancy to become less than 0.2 seconds ×: Time required for buoyancy to become 0 or more 0.2 seconds (3) Wire bonding characteristics Wire bonding characteristics are gold wire After bonding, the wire was pulled at 500 μm / sec and cut, and evaluated at the cutting position of the wire. The criteria for judging wire bonding characteristics are as follows.
(Circle): Wire cut | disconnect x: It peels on the joint surface of a wire and a sample (4) Reflectance The reflectance was evaluated by measuring the reflectance in 450-900 nm of the sample before and behind heat processing with an ultraviolet visible spectrophotometer. The heat treatment was performed at 200 ° C. for 1 hour. The criteria for determining the reflectance are as follows.
A: The reflectivity is 90% or more at 450 to 900 nm.
X: A wavelength with a reflectance of less than 90% at 450 to 900 nm exists.

  In Examples 1, 6, and 11, since no increase in contact resistance, deterioration in solder wettability, and deterioration in reflectance were observed, there was no adverse effect on the contact resistance, solder wettability, and reflectance due to the discoloration prevention treatment. I understand that. Moreover, in Examples 1, 6, and 11, since peeling at the bonding surface between the wire and the sample was not observed, it can be seen that there is no adverse effect on the wire bonding characteristics due to the discoloration prevention treatment.

Claims (6)

The inhibitor is selected from the group consisting of a benzotriazole compound represented by the following general formula (1), a mercaptobenzothiazole compound represented by the following general formula (2), and a triazine compound represented by the following general formula (3). In addition, 0.01 to 0.15 g / L of one or more compounds and 0.1 to 20 g / L of iodide and / or bromide are dissolved or dispersed in water, and the pH is adjusted to 4 to 7. A surface treatment agent for forming a highly heat-resistant film on a metal, characterized by being prepared.

(In the formula, R ₁ represents hydrogen, a substituted or unsubstituted alkyl group, and R ₂ represents an alkali metal, hydrogen, a substituted or unsubstituted alkyl group.)

(In the formula, R ₃ represents an alkali metal or hydrogen.)

[In the formula, R ₄ is —SH, an amino group substituted with an alkyl group, an alkenyl group or an aryl group, or an alkyl-substituted imidazolylalkyl; R ₅ , R ₆ are —NH ₂ , —SH or —SM (where M is an alkali Represents metal). ]   The surface treatment agent for forming a highly heat-resistant film on a metal according to claim 1, further comprising a surfactant.   The surface treatment agent for forming a highly heat-resistant film on the metal according to claim 1 or 2, wherein the metal is silver or a silver alloy.   A surface treatment agent for forming a highly heat-resistant film on a metal according to any one of claims 1 to 3, wherein the surface-treating agent is used for an LED reflecting material.   A substrate having a metal with a film formed on a surface, which is treated with a surface treatment agent for forming the highly heat-resistant film according to claim 1 on a metal. .   6. The base material having a metal with a film formed on the surface according to claim 5, wherein the base material is an LED reflecting material.