JPH10298788A - Tarnishing preventing solution for copper or copper alloy and tarnishing preventing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a tarnishing preventing soln. for copper or copper alloy excellent in tarnish preventing effect and heat resistance in an ordinary environment and having high adhesive strength to a resin at a low temp. by using a silane coupling agent and a nobler metal than copper or its salt as essential components and water or an org. solvent as a solvent. SOLUTION: This tarnishing preventing soln. contains 0.1 mg/l to 100 g/l silane coupling agent, 10 mg/l to 100 g/l nobler metal than copper or its salt and water or an org. solvent or further contains about 0.1-100 g/l pH buffer or about 1 μg/l to 10 g/l surfactant. The nobler metal is preferably Ag, Au, Pt, Pd, Rh, Ru, Ir or Os. An aminosilane or epoxysilane compd. may be used as the silane coupling agent. The surface of copper or copper alloy is preferably roughened or oxidized before applying this tarnishing preventing soln.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a lead frame,
The present invention relates to a discoloration inhibitor and a method for preventing discoloration of copper or copper alloy materials used for tabs, printed wiring boards, and the like.

[0002]

2. Description of the Related Art In general, high-speed partial silver plating is often performed on electronic component materials such as lead frames or tabs (these materials are generally of a copper or copper alloy type). . At that time, the abnormal silver deposition portion is selectively dissolved and removed using a silver stripper. After that, a resin sealing step is performed. In these steps, immersion in an acid or alkali solution, storage, heating, bonding, resin sealing, etc. are performed, so that adhesiveness to lead frames and tabs,
Heat resistance and chemical resistance are required. Furthermore, it is required that there be no discoloration during transportation / storage or heating.

For this reason, various discoloration prevention methods for lead frames have been proposed. For example, Japanese Patent Application Laid-Open No. 4-1
No. 60173 describes a copper discoloration inhibitor containing 5-methyl-1H-benzotriazole and the like. JP-A-6-350,000 describes a surface treatment agent for lead frames containing an alkoxysilane coupling agent and an organic solvent. However, although the former is excellent in the effect of preventing discoloration at room temperature, it has a problem in that the heat resistance is poor and the oxide film is easily peeled off during heating, so that the adhesive strength with the resin is reduced. In the latter, although the adhesive strength to the resin is increased, it has no effect of preventing discoloration at room temperature and has poor heat resistance. Accordingly, the present inventors have disclosed in Japanese Patent Application No. 8-122343, "A solution containing a heterocyclic compound containing nitrogen or sulfur or both in a molecule and acting as an inhibitor of copper is preferably a metal which is more noble than copper. A discoloration preventing liquid to which the salt is added "has been proposed. It has been pointed out that the discoloration preventing liquid of the type replacing the noble metal is excellent in the effect of preventing discoloration in a normal environment and also excellent in heat resistance, but has low adhesive strength to a resin at a low temperature. Therefore, in order to increase the adhesive strength with the resin, it was necessary to perform a heat treatment before the bonding.

[0004]

DISCLOSURE OF THE INVENTION The present invention has an excellent effect of preventing discoloration in a normal environment, has excellent heat resistance, and has a high adhesive strength to a resin at a low temperature. It was intended to provide an agent and a method for preventing discoloration.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and as a result, have found that a solution mainly containing a silane coupling agent and a metal or a salt thereof which is more noble than copper is used. Alternatively, it has been found that by immersing the copper alloy material, it is possible to simultaneously satisfy the discoloration prevention effect, the heat resistance, and the adhesiveness to the resin at a low temperature.

[0006] Based on this finding, the present invention provides: A discoloration preventing liquid for copper or copper alloy, characterized by comprising a silane coupling agent and a metal or a salt thereof nobler than copper as a main component, and further containing water or an organic solvent as a solvent.

[0007] 2. Silver or a metal nobler than copper,
The anti-tarnish liquid for copper or copper alloy according to the above 1, wherein the liquid is at least one metal selected from gold, platinum, palladium, rhodium, ruthenium, iridium and osmium or a salt thereof.

[0008] 3. The silane coupling agent is an aminosilane compound, an epoxysilane compound, a vinylsilane compound, a mercaptosilane compound, an alkylsilane compound,
3. The discoloration preventing liquid for copper or copper alloy according to any one of the above 1 or 2, wherein the liquid is at least one selected from a halogenosilane compound, a polymer type silane compound, an azole silane compound or a derivative thereof.

4. 0.1 mg of silane coupling agent
The liquid for preventing discoloration of copper or a copper alloy according to any one of the above items 1 to 3, which contains 1 to 100 g / l and contains a noble metal or a salt thereof which is nobler than copper and 10 mg / l to 100 g / l.

[0010] 5. Further, the above-mentioned items 1 to 4, further comprising a pH buffer and / or a surfactant.
Liquid for preventing discoloration of copper or copper alloy according to any of the above

6. A copper or copper alloy is immersed in a copper or copper alloy discoloration preventing liquid characterized by containing a silane coupling agent and a metal or a salt thereof which is more noble than copper, and further containing water or an organic solvent as a solvent. Or a method for preventing discoloration of copper or copper alloy, which comprises spraying or spraying the discoloration preventing liquid on copper or copper alloy.

7. It is characterized in that a discoloration preventing liquid containing at least one metal selected from silver, gold, platinum, palladium, rhodium, ruthenium, iridium and osmium or a salt thereof as a metal noble than copper or a salt thereof is used. The method for preventing discoloration of copper or a copper alloy according to the above item 6

8. Amino silane compounds, epoxy silane compounds, vinyl silane compounds, mercapto silane compounds, alkyl silane compounds as silane coupling agents,
8. The discoloration of copper or a copper alloy as described in 6 or 7 above, wherein a discoloration preventing liquid containing at least one selected from a halogenosilane compound, a polymer type silane compound, an azole silane compound or a derivative thereof is used. How to prevent

9. 0.1 mg of silane coupling agent
The copper or copper according to any one of the above items 6 to 8, wherein a discoloration preventing liquid containing 1 to 100 g / l and containing a noble metal or a salt thereof which is nobler than copper and 10 mg / l to 100 g / l is used. How to prevent discoloration of alloys

10. The method for preventing discoloration of copper or copper alloy according to any one of the above items 6 to 9, further comprising using a discoloration preventing solution containing a pH buffering agent and / or a surfactant.

11. The method for preventing discoloration of copper or copper alloy according to any one of the above 6 to 10, wherein the surface of copper or copper alloy is roughened or oxidized in advance before performing the treatment for preventing discoloration of copper or copper alloy.

[12] 12. The copper or copper alloy according to the above item 11, wherein the copper or copper alloy is roughened by any one of plating, chemical polishing, electrolytic polishing, paper polishing, blast polishing or honing polishing. Method

13. 12. A method for preventing discoloration of copper or a copper alloy according to the item 11, wherein the method of oxidizing the copper or the copper alloy is by immersion in an oxidizing agent solution, electrolytic oxidation, or by heating.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The anti-tarnish solution according to the present invention contains "a silane coupling agent and a metal or a salt thereof which is more noble than copper" as its main components. Here, the silane coupling agent is one selected from an aminosilane compound, an epoxysilane compound, a vinylsilane compound, a mercaptosilane compound, an alkylsilane compound, a halogenosilane compound, a polymer-type silane compound, or an azolesilane compound or a derivative thereof. What is necessary is just what contains the above. For example, amino silane, epoxy silane, imidazole silane, benzimidazole silane,
Benzotriazole silane and the like can be mentioned.

In the discoloration preventing liquid according to the present invention, one or more of these silane coupling agents are selected, and preferably 0.1 mg / l to 100 g / l (more preferably 10 mg / l to 100 g / l).
(mg / l to 10 g / l). This is because the content of the silane coupling agent is 0.1%.
When the amount is less than mg / l, the discoloration preventing effect is not sufficient,
Further, even if the content exceeds 100 g / l, no further effect can be expected.

In the anti-tarnish liquid according to the present invention, the metal or salt thereof which is nobler than copper has almost the same action.
Although it exhibits an effect, it is preferable to use at least one metal selected from silver, gold, platinum, palladium, rhodium, ruthenium, iridium and osmium, or a salt thereof. Most commonly, silver salts such as silver cyanide, potassium potassium cyanide, silver sodium cyanide, and silver nitrate, potassium gold cyanide, dichlorodiammine palladium, and rhodium sulfate can be exemplified.

At least one metal is selected from these noble metals or salts thereof, and preferably 10 mg / l to 10 mg / l.
0 g / l (more preferably, 100 mg / l to 10 g / l
l). This is because if the content ratio of a metal or a salt thereof which is nobler than copper is less than 10 mg / l, the amount of deposited metal is small and the heat resistance is not so much improved, and the content is more than 100 g / l. This is because no further effect can be expected.

Water is usually used as a solvent of the silane coupling agent and the metal or a salt thereof which is more noble than copper, but when the main component is hardly soluble in water,
Organic solvents such as alcohols and ketones are added as needed.

Further, the anti-tarnish solution according to the present invention can contain a pH buffer and / or a surfactant, if necessary. As the pH buffer, boric acid-based, phosphoric acid-based, and organic acid-based pH buffers can be used. When these are added, their content ratio is 0.1 to 100 g / l, Preferably, 1 to 50 g
/ L. As the surfactant, any of anionic, cationic and nonionic surfactants or a mixture thereof can be used. When these are added, the content thereof is 1 μg / l to 10 g / g.
l, preferably 10 μg / l to 1 g / l.

The pH of the anti-tarnish liquid according to the present invention is not particularly limited as long as the above components are dissolved. Further, the temperature of the anti-tarnish liquid is preferably 5 to 80 ° C,
More preferably, the temperature is set to 10 to 40 ° C.

In the treatment of copper or copper alloy using the above-mentioned anti-tarnish liquid according to the present invention, copper or copper alloy as a base material is immersed in the above-mentioned anti-tarnish liquid or the anti-tarnish liquid is treated with copper or copper. This can be done by spraying or spraying on the alloy. The processing time at this time is 0.1 second to 1
It may be 0 minutes, preferably 1 to 60 seconds. By this treatment, for example, an excellent discoloration preventing effect can be imparted even to a surface from which a silver electrolytic deposition layer has been selectively removed using a silver stripper.

Before performing the above-described discoloration prevention treatment, the surface of the copper or copper alloy material can be roughened or oxidized in advance to improve the adhesive force with the resin. As a method of roughening the material, any one of chemical polishing, electrolytic polishing, paper polishing, blast polishing, honing polishing and plating is possible. Specifically, for example, it is possible to roughen using the following method. a) Chemical polishing Immerse in 100 g / l solution of ammonium persulfate for 30 seconds. b) Electropolishing Electrolysis is performed in a 70% phosphoric acid solution using copper as a cathode at 2 V for 10 minutes. c) Paper polishing Polishing is performed using # 600 SiC polishing paper. d) Blast polishing A pressure of 3 kg / cm ² using alumina particles of # 100.
Blast polishing. e) Honing polishing Using # 100 alumina particles, pressure 3 kg / cm ²
Perform honing polishing. f) Plating Copper cyanide 30 g / l, potassium cyanide 45 g / l,
Electroplating is performed for 30 seconds at a cathode current density of 10 A / dm ² in a bath containing 4 g / l of potassium hydroxide.

The material can be oxidized by immersion in an oxidizing agent solution, by electrolysis or by heating. For example, it is possible to oxidize using the following method. a) Immersion in oxidant solution Sodium hypochlorite 30 g / l, phosphoric acid 15 g / l,
3 in an oxidizing agent solution containing 10 g / l of sodium hydroxide
Soak for 0 seconds. b) Electrolysis In a solution containing 100 g / l of sodium hydroxide, anodic electrolysis is performed at an anodic current density of 5 A / dm2 for 30 seconds. c) Heating Heating is performed at 250 ° C. for 1 minute. By performing these roughening treatments or oxidation treatments before performing the discoloration prevention treatment, it is possible to further improve the adhesive force between the copper or copper alloy material and the resin when the molding is performed thereafter.

The base material to be subjected to the discoloration prevention treatment in the present invention is a copper or copper alloy material such as a lead frame, a tab or a copper foil for a printed wiring board. Is not only solid materials consisting of copper or copper alloy, but also iron or iron alloy,
It goes without saying that all materials having a surface of copper or a copper alloy, such as a material in which a copper base plating treatment is applied to a metal lower than silver, such as nickel or a nickel alloy, are included.

[0030]

According to the present invention, there is provided a liquid for preventing discoloration of copper or a copper alloy, which comprises a silane coupling agent and a metal or a salt thereof which is more noble than copper, and further contains water or an organic solvent as a solvent. The reason why the surface of the copper or copper alloy material is provided with a discoloration prevention function and an adhesion improving function by contacting the copper or copper alloy material with the copper or copper alloy material by dipping, spraying, spraying or the like is as follows.

That is, when the anti-tarnish solution according to the present invention is brought into contact with a copper or copper alloy material, an oxide film is not formed on the surface of the copper or copper alloy material, and the surface thereof is more noble than copper. The metal "substitution layer coating" is formed uniformly and thinly with a thickness of about 10 to 1000 mm. The formation of the substitution layer coating of “a metal nobler than copper” protects the copper or copper alloy from the transportation or storage environment and prevents discoloration. In addition, since the substitution layer coating of “metal nobler than copper” has high heat resistance, “oxidation of itself” and “oxidation of copper or copper alloy surface” even when placed in a relatively high temperature environment. "Can be prevented, and no inconvenience such as peeling of the oxide film is caused. Of course, the formation of the substitution layer coating of “a metal nobler than copper” does not cause loss of the original characteristics desired for the copper or copper alloy material.

Further, the silane coupling agent, which is the main component of the anti-tarnish solution according to the present invention, makes uniform substitution of copper with a “metal nobler than copper” and also has a coupling effect of the silane coupling agent. Then, the metal and the resin are firmly bonded. As a result, an effect of preventing discoloration of copper or a copper alloy, an effect of improving adhesive strength to a resin, and an effect of improving heat resistance and moisture resistance are simultaneously provided.

Furthermore, by roughening the material before performing the discoloration prevention treatment, an anchor effect is generated and the adhesive strength is improved. In addition, since the bonding between the epoxy resin and the metal is caused by hydrogen bonding between the surface oxide or hydroxide of the epoxy resin and the metal surface, the hydrogen bonding increases by oxidizing the material before performing the discoloration prevention treatment. Also, the adhesive strength is improved.

Hereinafter, the present invention will be described in more detail with reference to examples.

[Example] Copper alloy plated with copper strike (Cu: 99.
After washing the lead frame substrate made of 7% -Sn: 2.0% -Ni: 0.2% -P: 0.03%) with pure water, it contains 100 g / l of 2-thiobarbituric acid as a substitution inhibitor and the pH is reduced to 10. After being immersed in the prepared pretreatment liquid at a liquid temperature of 30 ° C. for 10 seconds, and subsequently washed with a pure water flow for 10 seconds, KAg (CN) ₂ : 130 g / l K ₂ HPO ₄ : 100 g / l It was immersed in a high-speed electric silver plating solution whose pH was adjusted to 8.5, and subjected to silver plating at Dk = 70 A / dm2 for 10 seconds. After that, the silver-plated lead frame base material is washed with pure water, and then the silver plating layers at the other parts except the central part are dissolved and removed using a commercially available silver peeling solution, and then washed again with pure water. Then, it was immersed in a discoloration preventing liquid shown in Table 1.

[0035]

[Table 1]

Before immersion in the anti-tarnish solution, some of the samples were subjected to a chemical polishing, plating, or blast polishing to roughen the surface of the material. Chemical polishing was performed by immersing the raw material in a 100 g / l solution of ammonium persulfate for 30 seconds. In the case of plating, copper cyanide 30 g / l, potassium cyanide 45 g /
In a bath containing 1 g of potassium hydroxide and 4 g / l of potassium hydroxide, electroplating was performed at a cathode current density of 10 A / dm ² , and two types of plating having a plating thickness of 0.2 μm and 3.0 μm were prepared.
In the case of blast polishing, blast polishing was performed at a pressure of 3 kg / cm ² using # 100 alumina particles.

Each substrate immersed in the discoloration inhibitor shown in Table 1 was immersed in boiling pure water for 10 minutes, and the discoloration of the copper strike plated portion was visually determined. Here, the heat treatment of "immersing in boiling pure water for 10 minutes" is a process usually performed as an acceleration test when left in the air. Further, with respect to each of the substrates subjected to the above-mentioned discoloration prevention treatment, the "temperature at which the copper oxide film is peeled off by a tape test when heat-treated for 30 minutes" was examined to evaluate the heat resistance. Further, the resin adhesive strength at low and high temperatures was evaluated for each substrate. For resin bonding at a low temperature, the material was not heated before bonding the molding resin, and for resin bonding at a high temperature, the material was heated at 250 ° C. for 5 minutes before bonding the molding resin. The "share strength with epoxy-based molding resin" was examined for each case. The molding resin was cured at 175 ° C. for 5 hours.
As a comparative example, a discoloration preventing liquid containing imidazole as a main component instead of the silane coupling agent was used (Comparative Example 1), and epoxysilane was used as the silane coupling agent. A similar test was performed using a discoloration preventing liquid (Comparative Example 2) to which no metal salt was added, and the results were evaluated. Table 1 shows the results.
Are shown together.

From the results shown in Table 1, it can be seen that the treatment using the anti-tarnish liquid according to the present invention provides a very good anti-tarnish effect, and the treated surface has an oxide coating tape peeling temperature of 3%.
It was confirmed that high heat resistance of 80 to 400 ° C. was exhibited. All of the resin adhesive strengths at high temperatures showed a large adhesive strength of 40 kg / cm ² or more. At the same time, the resin adhesive strength at a low temperature showed a sufficiently large value of 25 kg / cm ² or more.

On the other hand, in the case where a discoloration preventing liquid containing imidazole as a main component instead of the silane coupling agent was used (Comparative Example 1), there was no problem in the adhesive strength at a high temperature. Resin adhesive strength at low temperature is 15.4k
g / cm ² . When epoxysilane was used as the silane coupling agent, but a discoloration preventing liquid (Comparative Example 2) which does not add a metal salt nobler than copper was used,
Heat resistance is as low as 320 ° C, and resin adhesive strength at high temperature is 22.
As small as 5 kg / cm ² , there was still a problem.

[0040]

As described above, according to the present invention, it is possible to provide a treated surface having excellent heat resistance and an excellent effect of preventing discoloration under a normal environment. It is possible to provide a discoloration preventing liquid for copper or copper alloy material which is excellent in both strength and resin adhesive strength at low temperature. Therefore, it is possible to greatly contribute to the reliability of electronic materials made of copper or a copper alloy such as a lead frame, a tab, a printed wiring board, etc., and an industrially useful effect is brought about.

Claims (13)

[Claims] 1. A discoloration preventing liquid for copper or a copper alloy, comprising a silane coupling agent and a metal or a salt thereof which is more noble than copper, and further containing water or an organic solvent as a solvent. 2. A metal or a salt thereof which is nobler than copper is silver,
The discoloration preventing liquid for copper or copper alloy according to claim 1, wherein the liquid is at least one metal selected from gold, platinum, palladium, rhodium, ruthenium, iridium and osmium, or a salt thereof. 3. The method according to claim 1, wherein the silane coupling agent is an aminosilane compound, an epoxysilane compound, a vinylsilane compound,
3. The method according to claim 1, wherein the compound is at least one selected from a mercaptosilane compound, an alkylsilane compound, a halogenosilane compound, a polymer-type silane compound, and an azole silane compound or a derivative thereof.
The anti-tarnish liquid for copper or copper alloy according to any one of the above. 4. A silane coupling agent of 0.1 mg / l
The discoloration preventing liquid for copper or copper alloy according to any one of claims 1 to 3, wherein the liquid contains noble metal or a salt thereof which is nobler than copper and contains 10 mg / l to 100 g / l. . 5. The method according to claim 1, further comprising a pH buffer and / or a surfactant.
The anti-tarnish liquid for copper or copper alloy according to any one of the above. 6. A copper or copper alloy discoloration preventing liquid characterized by containing a silane coupling agent and a metal or a salt thereof which is nobler than copper as a main component, and further containing water or an organic solvent as a solvent. A method for preventing discoloration of copper or a copper alloy, comprising immersing a copper alloy or spraying or spraying the anti-discoloration liquid on the copper or copper alloy. 7. A discoloration preventing liquid containing at least one metal selected from silver, gold, platinum, palladium, rhodium, ruthenium, iridium and osmium or a salt thereof as a metal or a salt thereof nobler than copper is used. The method for preventing discoloration of copper or a copper alloy according to claim 6, wherein: 8. A silane coupling agent comprising an aminosilane compound, an epoxysilane compound, a vinylsilane compound, a mercaptosilane compound, an alkylsilane compound,
The copper or copper alloy according to claim 6, wherein a discoloration preventing liquid containing at least one selected from a halogenosilane compound, a polymer-type silane compound, or an azole silane compound or a derivative thereof is used. Discoloration prevention method. 9. The silane coupling agent is added in an amount of 0.1 mg / l.
The copper or copper according to any one of claims 6 to 8, wherein a discoloration preventing liquid containing noble metal or a salt thereof which is nobler than copper and contains 10 mg / l to 100 g / l is used. A method for preventing discoloration of alloys. 10. The method for preventing discoloration of copper or a copper alloy according to claim 6, further comprising using a discoloration preventing liquid containing a pH buffer, a surfactant, or both of them. 11. The copper or copper according to claim 6, wherein the surface of the copper or copper alloy is roughened or oxidized before performing the discoloration prevention treatment on the copper or copper alloy. A method for preventing discoloration of alloys. 12. The copper according to claim 11, wherein the copper or copper alloy is roughened by any one of plating, chemical polishing, electrolytic polishing, paper polishing, blast polishing or honing polishing. Or a method for preventing discoloration of copper alloy. 13. The method for preventing discoloration of copper or copper alloy according to claim 11, wherein the method of oxidizing copper or copper alloy is by immersion in an oxidizing agent solution, electrolytic oxidation, or by heating.