JP3371072B2 - Copper or copper alloy discoloration prevention liquid and discoloration prevention method - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

BACKGROUND OF THE INVENTION Lead frame or electronic component materials such as tabs (which are often copper or copper alloys in general) are usually subjected to high speed partial silver plating. . At this time, the abnormal silver precipitation portion is selectively dissolved and removed by using a silver stripping solution. Then, a resin sealing process is performed. In these steps, since dipping in an acid or alkaline solution, storage, heating, bonding, resin sealing, etc. are performed, adhesion to lead frames, tabs, etc.,
Heat resistance and chemical resistance are required. Further, it is required that there is no discoloration during transportation / storage or heating.

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

[0004]

DISCLOSURE OF THE INVENTION The present invention is an anti-discoloration agent for copper or copper alloys, which has an excellent effect of preventing discoloration under normal environment and also has excellent heat resistance, and which has a large adhesive force with a resin at low temperature. It aims at providing an agent and a discoloration prevention method.

[0005]

In order to solve the above problems, the present inventor has conducted diligent research and, as a result, has found that a solution containing a silane coupling agent and a metal or a salt thereof, which is more precious than copper, as a main component is copper. It has also been found that it is possible to simultaneously satisfy the effect of preventing discoloration, heat resistance, and adhesiveness with a resin at low temperature by dipping a copper alloy material.

Based on this finding, the present invention provides: A discoloration-preventing liquid for copper or copper alloys, characterized in that it contains a silane coupling agent and a metal or a salt thereof that is more precious than copper as main components, and further contains water or an organic solvent as a solvent.

2. A metal that is more precious than copper or its salt is silver,
Discoloration preventive solution for copper or copper alloy as described in 1 above, which is one or more metals selected from gold, platinum, palladium, rhodium, ruthenium, iridium and osmium, or salts thereof.

3. A silane coupling agent is an aminosilane compound, an epoxysilane compound, a vinylsilane compound, a mercaptosilane compound, an alkylsilane compound,
One or more kinds selected from a halogenosilane compound, a polymer type silane compound, an azole silane compound or derivatives thereof, and the discoloration preventing liquid for copper or copper alloy according to any one of 1 or 2 above.

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

5. Furthermore, the above-mentioned 1 to 4 characterized in that it also contains a pH buffering agent and / or a surfactant.
Anti-tarnish solution for copper or copper alloy according to any one of 1.

6. Immersing copper or a copper alloy in a discoloration-preventing liquid for copper or a copper alloy, which comprises a silane coupling agent and a metal or a salt thereof which is more precious than copper as a main component, and further contains water or an organic solvent as a solvent. Alternatively, the discoloration preventing liquid is sprayed or sprayed on copper or a copper alloy, and the discoloration preventing method for copper or a copper alloy is characterized.

7. It is characterized by using a tarnish preventive liquid containing one or more metals selected from silver, gold, platinum, palladium, rhodium, ruthenium, iridium and osmium or salts thereof as a metal or a salt thereof more precious than copper. 6. The method for preventing discoloration of copper or copper alloy according to 6 above

8. Aminosilane compounds, epoxysilane compounds, vinylsilane compounds, mercaptosilane compounds, alkylsilane compounds, as silane coupling agents,
Discoloration of copper or copper alloy as described in 6 or 7 above, which uses 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. Prevention method

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

10. Furthermore, the discoloration preventing method for copper or copper alloy according to any one of 6 to 9 above, which comprises using a discoloration preventing liquid containing a pH buffer and / or a surfactant.

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

12. 12. The copper or copper alloy roughening method is any one of plating, chemical polishing, electropolishing, paper polishing, blast polishing or honing polishing, which prevents discoloration of copper or copper alloy. Method

13. The method for preventing discoloration of copper or a copper alloy according to the above 11, wherein the method for oxidizing the copper or the copper alloy is by immersion in an oxidant solution, electrolytic oxidation, or by heating.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The discoloration preventing liquid according to the present invention contains "a silane coupling agent and a metal more noble than copper or a salt thereof" 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 azole silane compound or a derivative thereof. Anything including the above may be used. For example, aminosilane, epoxysilane, imidazolesilane, benzimidazolesilane,
Examples thereof include benzotriazole silane.

In the discoloration preventing liquid according to the present invention, one or more kinds are selected from these silane coupling agents, preferably 0.1 mg / l to 100 g / l (more preferably 10 mg / l).
(mg / l to 10 g / l). This is because the content ratio of the silane coupling agent is 0.1.
If it is less than mg / l, the discoloration prevention effect is not sufficient,
Moreover, even if the content is more than 100 g / l, no further effect can be expected.

In the anti-tarnish solution according to the present invention, any metal or salt thereof which is nobler than copper has almost the same action.
Although effective, 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 silver cyanide, sodium cyanide, and silver nitrate, potassium gold cyanide, dichlorodiamminepalladium, and rhodium sulfate can be used.

One or more kinds are selected from these metals or their salts, which are nobler than copper, and preferably 10 mg / l to 10
0 g / l (more preferably 100 mg / l to 10 g / l
It is contained in the ratio of 1). This is because when the content ratio of the metal or its salt, which is more noble than copper, is less than 10 mg / l, the metal precipitation amount is small and the heat resistance is not improved so much, and when it is contained at a ratio of more than 100 g / l. This is because it is impossible to expect any further effect.

Water is usually used as a solvent for the silane coupling agent which is the main component and a metal or a salt thereof which is more precious than copper, but when the main component is difficult to dissolve in water,
If necessary, an organic solvent such as alcohol and ketone is added.

Further, the discoloration preventing liquid according to the present invention may contain a pH buffer and / or a surfactant, if necessary. As the pH buffer, it is possible to use a boric acid-based, phosphoric acid-based, or organic acid-based pH buffer, and when these are added, the content ratio thereof is 0.1 to 100 g / l, Preferably 1 to 50 g
/ L. As the surfactant, it is possible to use any of anionic, cationic and nonionic surfactants, or a mixture thereof, and when these are added, the content ratio thereof is 1 μg / l to 10 g /
1, preferably 10 μg / l to 1 g / l.

The pH of the discoloration preventing liquid according to the present invention is not particularly limited as long as it can dissolve the above components. The temperature of the discoloration preventing liquid is preferably 5 to 80 ° C,
The temperature is more preferably 10 to 40 ° C.

The treatment of copper or copper alloy using the above discoloration preventing solution according to the present invention is carried out by immersing the base copper or copper alloy in the above discoloration preventing solution or by applying the discoloration preventing solution to copper or copper. It can be done by spraying or spraying 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 the surface from which the electrolytic electrolytic deposition layer of silver has been selectively removed by using a silver stripping solution.

It is possible to improve the adhesive force with the resin by roughening or oxidizing the surface of the copper or copper alloy material in advance before the discoloration preventing treatment. As a roughening method of the material, any one of chemical polishing, electrolytic polishing, paper polishing, blast polishing, honing polishing or plating can be used. Specifically, for example, the following method can be used for roughening. a) Chemical polishing Immerse in a 100 g / l solution of ammonium persulfate for 30 seconds. b) Electropolishing In a 70% phosphoric acid solution, electrolysis is performed at 2 V for 10 minutes with copper as the cathode. c) Paper polishing Polish with # 600 SiC polishing paper. d) Blast polishing # 100 using alumina particles, pressure 3 kg / cm ²
Blast polishing with. e) Honing polishing # 100 using alumina particles, pressure 3 kg / cm ²
Honing polishing is performed. f) Plated 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 dipping in an oxidant solution, electrolysis, or 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 oxidizer solution containing 10 g / l sodium hydroxide
Soak for 0 seconds. b) Electrolysis Anodic electrolysis is carried out for 30 seconds at a anodic current density of 5 A / dm 2 in a solution containing 100 g / l of sodium hydroxide. c) Heating Heat treatment is performed at 250 ° C. for 1 minute. By performing the roughening treatment or the oxidation treatment before the discoloration preventing treatment, it becomes possible to further improve the adhesive force between the copper or the copper alloy material and the resin when the molding is performed thereafter.

By the way, the base material to be subjected to the discoloration preventing 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 a pure material consisting of copper or copper alloy, but also iron or iron alloy,
It goes without saying that it includes all materials having a surface of copper or a copper alloy, such as those obtained by subjecting a metal that is less base than silver, such as nickel or a nickel alloy, to a copper strike plating treatment.

[0030]

The discoloration-preventing solution for copper or copper alloys according to the present invention, characterized in that it contains a silane coupling agent and a metal or salt thereof which is more precious than copper as main components, 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 preventing function and an adhesiveness improving function by bringing the copper or copper alloy material into contact with the surface by dipping, spraying or spraying is as follows.

That is, when the discoloration preventing liquid according to the present invention is brought into contact with copper or a copper alloy material, an oxide film is not formed on the surface of the copper or copper alloy material, and the surface of the copper or copper alloy material is more noble than the above-mentioned "noble copper". A substitution layer film of "metal" is uniformly thinly formed with a thickness of about 10 to 1000Å. The formation of the "precious metal than copper" substitution layer coating protects the copper or copper alloy from the transportation or storage environment and prevents discoloration. In addition, since the substitution layer film of "a metal that is more precious than copper" has high heat resistance, even when placed in a relatively high temperature environment, "oxidation of itself" and "oxidation of the copper or copper alloy surface". Can be prevented, and the disadvantage of peeling of the oxide film does not occur. Of course, the formation of the "precious metal than copper" substitution layer coating does not cause the loss of the original properties desired for the copper or copper alloy material.

Further, the silane coupling agent which is the main component of the discoloration preventing liquid according to the present invention makes the substitution of copper and "a metal nobler than copper" uniform, and the coupling effect of the silane coupling agent. Then, firmly bond the metal and the resin. As a result, an effect of preventing discoloration of copper or a copper alloy, an effect of improving adhesive force with respect to resin, and an effect of improving heat resistance and humidity resistance are simultaneously provided.

Further, by roughening the material before the discoloration preventing treatment, the anchor effect is produced and the adhesive strength is improved. Also, since the adhesion between the epoxy resin and the metal is due to the hydrogen bond of the surface oxide or hydroxide of the epoxy resin and the metal surface, the hydrogen bond is increased by oxidizing the material before the discoloration prevention treatment. After all, the adhesive strength is improved.

Hereinafter, the present invention will be described more specifically by comparing the present invention with comparative examples.

Example: Copper alloy plated with copper strike (Cu: 99.
7% -Sn: 2.0% -Ni: 0.2% -P: 0.03%) After washing the lead frame base material with pure water, the substitution inhibitor 2-thiobarbituric acid was added to 100 g / l and the pH was adjusted to 10 It is immersed in the prepared pretreatment liquid at a liquid temperature of 30 ° C. for 10 seconds, then washed with a pure water stream for 10 seconds, and then contains 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 silver plating was performed at Dk = 70 A / dm2 for 10 seconds. After that, the silver-plated lead frame base material was washed with pure water, and then the silver-plated layers at other portions except the central portion were dissolved and removed using a commercially available silver stripping solution, and then washed again with pure water. It was immersed in the discoloration preventing liquid shown in Table 1.

[0035]

[Table 1]

Before dipping in the discoloration preventing liquid, some of the samples were roughened by chemical polishing, plating, or blast polishing. The chemical polishing was performed by immersing the material in a 100 g / l ammonium persulfate solution for 30 seconds. In the case of plating, copper cyanide 30 g / l, potassium cyanide 45 g / l
In a bath containing 1 and 4 g / l of potassium hydroxide, electroplating was performed at a cathode current density of 10 A / dm ² to prepare two types of plating thicknesses of 0.2 μm and 3.0 μm.
In the case of blast polishing, # 100 alumina particles were used and blast polishing was performed at a pressure of 3 kg / cm ² .

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

From the results shown in Table 1, the treatment using the anti-tarnish solution according to the present invention has a very good anti-discoloration effect, and the treated surface has a tape peeling temperature of the oxide film of 3
It was confirmed that the heat resistance was as high as 80 to 400 ° C. The resin adhesive strength at high temperature was 40 kg / cm ² or more, which was a large adhesive strength. At the same time, the resin adhesive strength at low temperature was 25 kg / cm ² or more, which was a sufficiently large value.

On the other hand, in the case of using the discoloration preventing liquid containing imidazole as a main component instead of the silane coupling agent (Comparative Example 1), there was no problem in the adhesive strength at high temperature. Resin adhesion at low temperature is 15.4k
It was as low as g / cm ² . Further, when epoxy silane was used as the silane coupling agent, but when a discoloration preventing liquid (Comparative Example 2) containing no metal salt nobler than copper was used,
Heat resistance is as low as 320 ° C and resin adhesion at high temperature is 22.
It was as small as 5 kg / cm ^2, and there was also a problem.

[0040]

As described above, according to the present invention, it is possible to provide a treated surface having excellent heat resistance as well as excellent discoloration-preventing effect in a normal environment, and resin bonding at high temperature. It is possible to provide a discoloration preventing liquid of a copper or copper alloy material, which is excellent in both the strength and the resin adhesive strength at low temperature. Therefore, it is possible to greatly contribute to the reliability of copper or copper alloy electronic materials such as lead frames, tabs, and printed wiring boards, and industrially useful effects are brought about.

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C23F 11/00

Claims (13)

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