WO2003040432A1

WO2003040432A1 - Nickel-based surface treatment films excellent in heat-resistant adhesion to resin

Info

Publication number: WO2003040432A1
Application number: PCT/JP2002/010825
Authority: WO
Inventors: Jun Kawaguchi; Hiroki Hayashi
Original assignee: Nihon Parkerizing Co., Ltd.
Priority date: 2001-11-08
Filing date: 2002-10-18
Publication date: 2003-05-15
Also published as: CN1568380A; TW574420B; JP2003147549A; KR20040054703A; JP4027642B2

Abstract

A nickel-based surface treatment film which is excellent in heat-resistant adhesion to a resin and has a two-layered structure formed on a subject material, characterized by containing nickel and phosphorus in the lower layer being in contact with the material and containing nickel, oxygen and phosphorus in the upper layer provided thereon, or containing nickel and boron in the lower layer and containing nickel, oxygen and boron in the upper layer provided thereon, or containing nickel, phosphorus and boron in the lower layer and containing nickel, oxygen, phosphorus and boron in the upper layer provided thereon.

Description

Specification

Nickel-based surface treatment film with excellent heat-resistant adhesion to resin

The present invention relates to a nickel-based surface treatment film formed on a surface of a metal substrate in order to provide a very strong adhesive force when bonding the substrate, particularly a metal substrate to a resin. . More specifically, the present invention relates to a nickel-based surface treatment film that can maintain excellent adhesive strength even when the metal-resin joined body is placed in a high temperature environment of 200 ° C. to 300 ° C. . Background art

Electronic and electrical components such as printed wiring boards, lead frames, and LSIs often use joints between metal and resin. In particular, in the case of thermosetting resins such as epoxy resin and polyimide resin or thermoplastic resin with high molding temperature used in such fields, when molding these resins, the entire part is kept at 200 ° C to 300 ° C. Exposure to temperatures as high as 0 ° C is required. In addition, in order to form a wiring pattern with copper foil adhered on a resin, it is necessary to go through a severe manufacturing process that comes into contact with chemicals such as organic solvents, acids and alkalis. In addition, soldering is used when mounting active components such as semiconductor devices and passive components such as LCRs.However, lead soldering cannot be used due to recent environmental issues, so the solder reflow temperature is becoming increasingly high. It is becoming.

In such a situation, if the adhesion between the metal substrate and the resin is poor, especially at high temperatures, the moisture adsorbed on the metal surface and the water absorbed at the bonding interface during the manufacturing process expand and the surface of the metal substrate is expanded. This causes swelling, etc., which impairs the internal corrosion resistance, and in some cases, the resin is cracked, and the wiring pattern is broken. The method of mechanically roughening the metal surface and forming a so-called anchor has long been used to improve the adhesion between the metal substrate and the resin. However, such machining tends to result in poor productivity and high cost, and the fine particles generated during the machining often impair the precision of electronic / electric parts. Therefore, in practice, it is generally possible to perform some surface treatment on the metal substrate surface side.

For example, phosphating in steel materials, copper and copper alloys

A typical example is a copper oxide treatment called “black dyeing”. The former involves contacting with a phosphoric acid aqueous solution in which a heavy metal having a very low solubility product with tertiary phosphoric acid, such as zinc, is dissolved.The latter is immersed in a strong alkaline aqueous solution containing an appropriate oxidizing agent and boiled. How to

However, most of the films formed by the phosphate treatment have water of crystallization, so the crystals are broken at a temperature of about 200 ° C at most, and the heat resistance of the film is poor. Although the adhesiveness at the initial stage of bonding is good, the bonding strength decreases with time due to poor durability, and the initial adhesive strength cannot be maintained even with heat treatment.

On the other hand, in Japanese Patent Application Laid-Open No. 9-209916 and Japanese Patent Application Laid-Open No. 9-172125, the adhesion is improved by performing a chromate treatment on the surface of the metal substrate. I'm making it. Further, Japanese Patent Application Laid-Open No. 2000-183032 discloses a method of forming a special chromium compound layer having a large number of fine flake-like projections on the surface by using an electrolytic method. I have.

However, all of these methods use hexavalent chromium compounds that are harmful to the surface treatment solution, and it is thought that hexavalent chromium is also contained on the surface of the formed metal substrate, Not preferred. Disclosure of the invention

The present invention has been made to solve the above problems of the prior art, and an object of the present invention is to provide a method for manufacturing a metal substrate and a resin without using a substance causing environmental pollution such as hexavalent chromium. An object of the present invention is to provide a surface-treated film having excellent adhesiveness with a coating, particularly at high temperatures. The present inventors have conducted intensive studies to solve the above problems of the prior art, and as a result, have focused on nickel metal which is generally excellent in heat resistance and stability over time and nickel oxide formed on its surface. However, the introduction of a third element into them has led to the discovery of a new nickel-based surface treatment film that is extremely excellent in adhesion to resins.

That is, the present invention relates to a nickel-based surface treatment film having a two-layer structure formed on a target material, wherein nickel and phosphorus are provided in a lower layer in contact with the surface of the material, and nickel, oxygen and Provided is a nickel-based surface treatment film having excellent heat-resistant adhesion to a resin characterized by containing phosphorus.

Further, boron can be used as an element instead of phosphorus contained in the nickel-based surface treatment film of the present invention.

Further, as an element contained in the nickel-based surface treatment film of the present invention, phosphorus and boron may coexist.

Further, the content ratio of phosphorus and / or boron to nickel in the nickel-based surface treatment film is more preferably such that the content ratio of the upper layer is larger than that of the lower layer, that is, the following relationship is satisfied.

[(Phosphorus and / or boron) / Ni] lower layer [[phosphorus and / or boron) / Ni] upper layer

Further, the upper layer of the nickel-based surface treatment film preferably has a columnar structure, and more preferably has a fine gap between the columns of the columnar structure.

The nickel-based surface treatment film of the present invention is preferably formed on copper or a copper alloy.

The nickel-based surface treatment film of the present invention preferably has a gray, gray-black or black appearance.

Hereinafter, the nickel-based surface treatment film of the present invention will be described in more detail. The nickel-based surface treatment film of the present invention has a two-layer structure in which metal nickel and phosphorus, Z or boron are disposed on the lower layer in contact with the surface of the material, that is, an upper layer further includes a layer containing oxygen. The target material is particularly limited as long as the metallic nickel can be formed with sufficient adhesion to the target material. Not determined. However, in the field of electronic and electrical components, in particular, heat resistance between copper or a copper alloy and a resin is often required, so copper will be mainly described as a target material.

FIG. 1 shows a cross-sectional scanning electron microscope (SEM) image of the nickel-based surface treatment film of the present invention, and FIG. 2 shows a surface SEM image thereof. Reference numeral 1 in FIG. 1 indicates an upper columnar structure (including nickel, oxygen, and phosphorus) of the nickel-based surface treatment film of the present invention, and reference numeral 2 in FIG. And the reference numeral 3 in FIG. 1 indicates a copper substrate. FIG. 2 shows a surface SEM image (X1000) of the nickel-based surface treatment film of the present invention.

As shown in FIG. 1, the upper layer of the surface treatment film of the present invention has a columnar structure, and fine gaps are observed between the columns (comb structure). Therefore, when this is observed from the surface (Fig. 2), although it is irregular, it is observed as extremely fine irregularities on the order of several 10 O nm to several 10 O nm, and it is a huge, very effective when bonding with resin. A substantial surface area can be obtained.

According to the analysis by XPS, the nickel in the upper layer is in an oxidized state and its thickness is about 50 O nm, but the oxide formed on the mere metallic nickel is thinner than this, and the present invention Is not formed. Such a form can be obtained by introducing the third element introduced in the present invention, that is, phosphorus and / or boron. Empirically, it is preferred that these third elements range from 2% to 50% by weight. If the content is less than 2% by weight, such a form cannot be obtained, and if the content exceeds 50% by weight, formation of a nickel film having such a composition becomes gradually difficult as the content increases. That is, it is economically disadvantageous.

The height of the upper columnar structure of the nickel-based surface treatment film of the present invention is preferably in the range of 50 to 300 orchids. If it is less than 5 O nm, fine irregularities on the surface will not be sufficiently formed, and if it exceeds 300 O nm, the irregularities will be coarse. On the other hand, the thickness of the lower metallic nickel layer is not particularly limited. However, in order to sufficiently cover the surface of the target material without exposing it, it is preferable that the length is 0.5 m or more. Good. Also, since unnecessary thick films are economically disadvantageous, an upper limit of 5 / m would be sufficient.

The appearance of the nickel-based surface treatment film of the present invention is gray, gray-black to black. This seems to be due to the columnar structure with gaps absorbing visible light as shown in FIGS. 1 and 2, which is particularly preferable in the field of electronic and electrical components. When observing the adhesive surface (surface treated film surface of the present invention) through the resin from the copper wiring pattern side, if it shows a black color, the contrast with the pattern becomes clear, and the inspection of the pattern becomes optical. This is advantageous when it is performed on a regular basis.

The nickel-based surface treatment film of the present invention can be formed by forming a metal nickel layer on a target material by various methods and then oxidizing the surface. Although a physical method such as PVD can be used to form the nickel metal layer, a wet surface treatment method such as an electroplating method or an electroless plating method is superior in mass productivity. Hereinafter, a plating method for co-depositing the third element will be described. In order to co-deposit phosphorus as a third element, in the case of electroplating, hypophosphorous acid or phosphorous acid may be further added to a well-known pet bath. In the case of electroless plating, a commercially available type using hypophosphorous acid as a reducing agent may be used.

Next, in order to cause eutectoid of boron as a third element, an electroless plating bath using a boron-containing reducing agent such as DMAB (dimethylamporane) may be used. Furthermore, when DMAB and hypophosphorous acid are used at the same time as the reducing agent, phosphorus and boron can be co-deposited at the same time. These are all commercially available.

On the other hand, depending on the additive added to the plating solution, carbon, nitrogen, sulfur and zinc can be co-deposited in addition to phosphorus and / or boron. In the sense of blackening, these methods work in a more favorable direction. For example, it becomes possible by introducing the additives described below.

In other words, to make nitrogen co-fold, aniline, monoethylamine, and Represented by nolamine, dimethylamine, triethanolamine, triamine triacetic acid, pyridine, imidazole, morpholine, O-phenanthroline, glycine, glutamic acid, alanine, serine, hydrazine, aspartic acid, ethylene diamine What is necessary is just to add a nitrogen-containing organic substance. For the co-deposition of sulfur, N, N-ethyldithiol sodium rubinate, 1,3-ethylethyl-2-thiourea, methionine, etyonin, cystine, cystine, glutathione, thioglycolic acid, saccharin, dipyridine, 1,2 , 3-Venzotriazole-2 monothiazoline-2-thiol, thiazole, thiourea, thiozol, thioindoxylic acid, o-sulfonamide benzoic acid, sulfanilic acid, methyl orange, naphthonic acid, naphthalene-α-snolefone Sulfur-containing organic compounds such as acid, 2-mercaptobenzothiazole, sulfadiazine, and rhodanammon may be added. To co-fold zinc, a zinc compound such as zinc carbonate, zinc oxide, zinc chloride, and zinc sulfate may be added. Finally, carbon can be co-deposited by adding an amine organic compound typified by diethylenetriamine and the like.

When the above plating is applied to copper and copper alloys, for example, in the case of electroplating, the copper surface may be cleaned and then directly electroplated. When a bath using an acid as a reducing agent is used, copper cannot be applied as it is because it has no catalytic activity for hypophosphorous acid. In such a case, a small amount of palladium plating may be applied as a pretreatment by plating with palladium or the like, and electric nickel plating may be performed thinly (about submicron) as strike plating, followed by electroless nickel plating.

After forming a predetermined nickel plating layer on the target material, a columnar texture layer is formed on the surface. For this purpose, it is effective to contact the acid with an appropriate oxidizing agent. Specifically, a necessary amount of an oxidizing agent such as nitric acid, permanganic acid, ferric ion or hydrogen peroxide may be added to a base of phosphoric acid, sulfuric acid, or hydrochloric acid. Alternatively, the anode may be electrolyzed in the base aqueous acid solution. Applying such an oxide formation process to a mere metallic nickel surface However, the third element such as phosphorus introduced into the nickel-based surface treatment film of the present invention generally makes the crystal of metallic nickel finer, It is thought that this results in the formation of the characteristic columnar texture layer of the present invention as a result of miniaturizing the distribution state of the anode and the power source of the local battery formed by the oxidation treatment. It is. In fact, according to the analysis of XPS and the like, the content ratio of the third element such as phosphorus to nickel is larger in the upper layer than in the lower layer. In other words, this suggests that nickel is more preferentially dissolved by the oxidation treatment, and that phosphorus and the like remain. The oxygen contained in the columnar structure in the upper layer is introduced along with such an oxidation treatment, and the content of the oxygen increases in the surface layer and decreases toward the lower layer. The resin to be bonded to the nickel-based surface treatment film of the present invention is not particularly limited. However, in the field of electronic and electrical components, epoxy resins and polyimide resins are frequently used and are the main object of the present invention. From the viewpoint of adhesion, a resin having a lower glass transition temperature can be softened at a high temperature and can reduce the difference in coefficient of thermal expansion between a metal and a resin. However, such a resin has a lower glass transition temperature because the heat resistance of the resin itself is reduced. Empirically, the nickel-based surface treatment film of the present invention is particularly effective for such a resin having a high glass transition temperature.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a cross-sectional SEM image (X3000) of the nickel-based surface treatment film of the present invention.

FIG. 2 shows a surface SEM image (X1000) of the nickel-based surface treatment film of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described specifically with reference to Examples of the present invention and Comparative Examples. Example 1

After applying 1 m strike nickel plating to a 300 mm X 300 mm X 0.5 mm copper plate (JISC 1100) surface using a watt bath, the phosphorus content becomes 9% by weight. It was immersed in the electroless plating bath prepared as described above to form a 5 μm electroless Ni-P alloy layer. Furthermore, this was immersed in an oxidation treatment solution in which 75% phosphoric acid and 677.5% nitric acid were mixed at a volume ratio of 90:10 at 40 ° C for 3 minutes. A nickel layer in which phosphorus was concentrated was formed on the surface of the alloy layer. The surface after the oxidation treatment had a beautiful black appearance with no gloss. Analysis of phosphorus in the depth direction by XPS revealed that it was 35% by weight in the outermost layer and 8.8% by weight in the lower layer (the lower part of the columnar structure). FIG. 1 and FIG. 2 are for the first embodiment. Next, a polyimide adhesive (“Neoflex double-sided adhesive sheet” manufactured by Mitsui Chemicals, Inc.) was adhered to the copper plate having been subjected to the nickel-based surface treatment to a thickness of 50 m. A copper foil of μm was arranged and press-bonded under the conditions of a pressing pressure of 50 kg / cm ² , a heating temperature of 250 ° C, and a heating time of 2 hours. This sample was cut into 5 mm squares, left in a heated and moist environment at 85 ° C and 85% RH for 24 hours to promote deterioration, and floated in a molten solder bath at 270 ° C. As a result, no longer than 300 seconds was observed.

The details of the plating bath and the processing conditions used in Example 1 are described below. The strike nickel plating is performed in a hot water bath, that is, in a reagent bath (nickel sulfate: 330 gZL, nickel chloride: 45 gZL, boric acid: 38 g / L). The test was performed at a bath temperature of 50 ° C. with a nickel plate as an anode and a cathode current density of 5 A / dm ² . Electroless plating bath: Sodium hypophosphite: 0.15 mol ZL, ammonium sulfate: 0.5 mol / L, trisodium citrate: 0.2 mol / L, nickel sulfate: 0 Each of the reagents was dissolved in deionized water to a concentration of 0.1 m1 / L, and the pH was adjusted to 9 by adding caustic soda. The electroless Ni-P alloy plating bath adjusted in this way was heated to 90 ° C to reduce the electroless plating. Then, the Ni-P alloy layer was formed.

Example 2

The same test as in Example 1 was performed using the following electroless Ni-B alloy plating bath instead of the electroless Ni-P alloy plating bath. For electroless Ni-B alloy plating bath, nickel chloride: 0.126 mol ZL, DMA B: 0.06 mol / L, malonic acid: 0.378 mol / L, TIN〇 ₃ : The reagents were respectively dissolved in deionized water so as to have a concentration of 70 mg / L, and the pH was adjusted to 6 with aqueous ammonia. The electroless Ni-B alloy plating bath thus adjusted was heated to 70 ° C and used. The boron content in the obtained Ni_B alloy film was 2.8% by weight. This was subjected to an oxidation treatment in the same manner as in Example 1 to give a gray-black appearance. Similarly, after bonding to a copper foil via polyimide adhesive and placing it in a heated and humid environment, the heat resistance of the solder was examined, and blistering occurred in the copper foil in 240 seconds.

Example 3

Example phosphorous acid 1 0 g / L was added to the Wa Tsu preparative bath for scan trike plated used in 1, temperature 4 0 ° C, current density: cathode electrolysis performed at 5 A / dm ² conditions, A Ni-P alloy film having a phosphorus content of 10% by weight was formed at 5 βm. When subjected to the oxidation treatment in the same manner as in Example 1, a beautiful black appearance was exhibited. Hereinafter, a sample similar to that of Example 1 was prepared and evaluated, and no abnormality was found in the solder heat resistance after 300 seconds.

Comparative Example 1

Using the Ni strike plating bath used in Example 1 as it was, a 3 μm nickel plating was formed, and the same oxidation treatment as in Example 1 was performed. However, although the gloss was slightly lost, it had an almost white appearance. Hereinafter, the same sample as in Example 1 was prepared and evaluated. As a result, the adhesive layer was peeled off within 2 to 3 seconds, and the adhesive layer was peeled off.

According to Examples 1 to 3 above, by applying the nickel-based surface treatment film of the present invention and then adhering to the resin, it is possible to obtain extremely good heat resistance even after exposure to, for example, a high-temperature and wet environment. it can. On the other hand, it can be understood that good adhesion cannot be obtained by simply oxidizing the nickel film surface as in Comparative Example 1.

Industrial applicability

By applying the nickel-based surface treatment film of the present invention, when bonding a metal substrate and a resin, it is possible to impart excellent wet resistance and high-temperature adhesion at high temperatures. High reliability can be provided. Further, as an incidental effect, the surface treatment film of the present invention has a dull black appearance, so that a good contrast can be obtained when optically inspecting electronic and electrical components. To improve the detection accuracy.

Claims

The scope of the claims

1. A nickel-based surface treatment film having a two-layer structure formed on a target material, wherein nickel and phosphorus are contained in a lower layer in contact with the surface of the material, and nickel, oxygen, and phosphorus are contained in the upper layer. Nickel-based surface treatment film with excellent heat-resistant adhesion to resin.

2. A nickel-based surface treatment film having a two-layer structure formed on a target material, wherein the lower layer in contact with the surface of the material contains nickel and boron, and the upper layer contains nickel, oxygen, and boron. A nickel-based surface treatment film with excellent heat-resistant adhesion to resins.

3. A nickel-based surface treatment film having a two-layer structure formed on a target material, wherein nickel, phosphorus, and boron are provided in a lower layer in contact with the surface of the material, and nickel, oxygen, phosphorus, and A nickel-based surface treatment film that contains boron and has excellent heat-resistant adhesion to resins.

4. The content ratio of phosphorus and / or boron to nickel in the nickel-based surface treatment film is such that the content ratio of the upper layer is larger than that of the lower layer and has the following relationship. A nickel-based surface treatment film excellent in heat-resistant adhesion to the resin according to any one of claims 3 to 3.

5. The upper layer of the nickel-based surface treatment film has a columnar structure, and a fine gap is provided between the columns of the columnar structure. A nickel-based surface-treated coating excellent in heat-resistant adhesion to the resin described in the above.

6. A nickel-based surface treatment film formed on copper or a copper alloy and having excellent heat-resistant adhesion to the resin according to any one of claims 1 to 5.

7. The nickel-based surface treatment film having excellent heat-resistant adhesion to the resin according to any one of claims 1 to 6, wherein the nickel-based surface treatment film has a gray, gray-black or black appearance.