JP3479702B2 - Surface coating material by tin and tin-lead alloy plating, and electronic parts using the coating material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface coating material by tin and tin-lead alloy plating, and an electronic component using this coating material, which is specified to crystals of β-tin in tin or tin-lead alloy plating film. What provides the orientation of.

[0002]

BACKGROUND OF THE INVENTION Leads, electrodes, etc. of electronic devices such as semiconductor devices and connectors are coated with a tin or tin-lead alloy electrodeposition film mainly for the purpose of improving solderability. In the manufacturing process of these electronic parts
(Specifically, for the purpose of mounting on a semiconductor substrate, etc.), electroplated leads, electrodes, etc. may be bent using a mold, or subjected to various machining such as cutting or cutting. Many. However, since the tin or tin-lead alloy plating film has a soft property, when post-processing such as bending is performed, shavings of the plating film are generated from the processed part, and conventionally, it is effective to prevent this. The reality was that there was no means.

[0003]

When the plating film shavings are generated during the above-mentioned machining, there are the following adverse effects. (1) If shavings adhere to and remain on the leads and electrodes, they may cause a short circuit of electronic components, which significantly impairs the reliability of the components. (2) When repeated machining is performed, shavings adhere to and grow on the mold, reducing the machining accuracy of the mold.Therefore, it is necessary to clean the mold at regular intervals. Lower. (3) The shavings attached to the mold may be transferred to the lead or the like, which causes a problem of reducing the reliability of the component as described in (1) above.

According to the present invention, when a surface coating material such as a lead of an electronic component covered with a tin or tin-lead alloy plating film is machined, the amount of shavings of the plating film is suppressed to a low level. This is a technical issue.

[0005]

Means for Solving the Problems For example, Japanese Patent Laid-Open No. 5-25
Japanese Patent No. 689 discloses a sliding bearing used for a crankshaft of an engine, a large end portion of a connecting rod, and the like, and when a crystal structure of a lead alloy constituting a surface layer of the bearing is specified, the surface layer is provided with an oil retaining property. It is disclosed that the anti-seizure property can be improved by providing the anti-glare agent.

The inventors of the present invention have conducted extensive studies as a starting point of the technique disclosed in the publication, and as a result, the orientation of β-tin crystals in the plated film was found to be the amount of shavings generated in the plated film during bending. The present invention has been completed based on the finding that the amount of shavings generated can be suppressed by controlling the crystal orientation.

That is, the present invention 1 relates to tin-containing metal on a base metal.
In a surface coating material for coating a lead alloy plating film by electroplating, the <001> direction of the Miller index in the β-tin crystal lattice in the plating film is 90 to 35 degrees with respect to the external force direction parallel to the surface of the base metal. The β-tin crystal is preferentially oriented so that the β-tin crystal has a high angle.

[0008]

The present invention 2 is a tin-plated skin on a base metal.
In the surface coating material for coating the film by electroplating,
In the plating film in the direction of external force parallel to the surface of the base metal
Miller index <001> in the β-tin crystal lattice of
The β-smoothness so that the direction forms a high angle of 90 to 35 degrees.
Tin plating characterized by preferentially orienting the crystals of copper
Is a surface coating material.

The invention 3 is the same as the invention 1 described above.
Z-Lead alloy content of lead is less than 20%
Surface coating by tin-lead alloy plating characterized by
It is a material.

The present invention 4 is any one of the above inventions 1 to 3.
In this case, the thickness of the plating film should be 1 to 30 μm.
Surfaces with tin and tin-lead alloy plating characterized by
It is a coating material.

A fifth aspect of the present invention is the plating bath according to any one of the first to fourth aspects, which contains a tin soluble salt or a tin and lead soluble salt, an organic sulfonic acid, and a surfactant as main components. According to the present invention, the base metal is electroplated.

In a sixth aspect of the present invention, the leads and electrodes are the same as those of the present invention.
An electronic component, which is the surface coating material according to any one of 1 to 5 .

According to a seventh aspect of the present invention, there is provided an electronic component according to the sixth aspect.
It is a semiconductor device and a connector .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The base metal to be surface-coated can be selected from any material including 42 alloy, copper alloy and Kovar, and is not limited to a specific material. On the surface of the base metal, there may be an underplating layer such as nickel or copper applied by an electroplating method or an electroless plating method. The thickness of the tin or tin-lead alloy plating film is 1 to 30 μm.
m is preferable, and 30 μm indicates a temporary upper limit of the usual thickness when plating is applied, but a film thickness of more than this may be used. The tin - content of lead in the lead alloy plating is preferably 20% or less, the lead exceeds 20%, the properties of the alloy becomes too soft, as in the present invention 1,
Even if the orientation of β-tin is controlled under specific conditions,
It becomes difficult to effectively suppress the generation of shavings in the plating film during machining.

Usually, the plating film is a polycrystal, and β
-The preferential orientation of tin crystals does not mean that all β-tin crystals in the film are oriented in a specific orientation, but statistically the majority (that is, as a tendency) falls within a certain range. It means that it is oriented in the azimuth direction. Therefore, for example, in the tin-lead alloy plating film of the present invention 1, the β-tin crystal has a Miller index <001> of the unit lattice.
The direction is 90 to 3 with respect to the direction of the external force applied to the surface coating material.
A crystal may be partially included in a random orientation deviating from the above-described statistically aligned orientation, while the majority is oriented so as to be statistically aligned within a range of 5 degrees. In addition, the present invention 2
The meaning of the orientation is the same in the tin film.

In general, the electronic devices and connectors mentioned above
Bending, cutting, etc. performed in the manufacturing process of electronic parts such as
In various machining such as cutting (or manual machining)
Is often processed along the surface of the base metal.
The present invention 1, which is directed to an alloy plating film, is formed of β-tin.
The <001> direction of the Miller index in the crystal lattice is
Related to the processing direction parallel to the base metal surface, that is, the external force direction
It is a digit. Further, the present invention 2 for a tin film
Similarly, in the <001> direction of β-tin crystal,
It is along an external force direction parallel to the surface.

When electroplating the above plating film,
Β due to many factors such as plating bath composition and plating conditions
-The orientation of the tin crystals changes. However, there are many factors between the composition and plating conditions of these plating baths and the orientation of β-tin in the obtained tin or tin-lead alloy plating film. There is no (clear) law (which cannot be specified), and there are many unknown parts.

Factors of the composition of the plating bath include the concentration and type of the metal-soluble salt of tin and / or lead, the concentration and type of acid, and the concentration and type of various additives such as surfactants and wetting agents. Can be mentioned. Further, the composition of the electroplating bath is, as shown in the present invention 5 , a small salt of tin and / or lead, an organic sulfonic acid, an interface, and an interface because of their low corrosiveness and easy drainage treatment. An organic sulfonic acid bath containing an activator as a main component is preferable. Various surfactants such as nonionic, amphoteric, cationic and anionic can be used as the surfactant.

On the other hand, the present applicant has filed Japanese Patent Application No. 7-27833.
The following technical matters are described in No. 1. (1) When a specific trialkylbenzil ammonium salt is added to a tin or tin-lead alloy plating bath, the tin or tin-lead alloy plated coating material may be bent or cut, and after-treatment such as cutting may be performed. It is possible to effectively reduce the adverse effects such as cracks in the plating film. (2) In addition to the specific trialkylbenzil ammonium salts, the addition of aromatic sulfonic acids in combination can further promote the effect of preventing cracking of the plated film in the post-processing.

Usually, when post-processing such as bending is performed on a surface coating material plated with tin or a tin-lead alloy, in addition to the harmful effects of shavings, cracks often occur. Therefore, with a soluble salt of tin and / or lead,
When the organic sulfonic acid and the organic sulfonic acid bath containing a surfactant as a main component are added together with the specific trialkylbenzil ammonium salt or aromatic sulfonic acid, the shavings of the plating film can be suppressed at the same time. Also, it can be expected to prevent the occurrence of cracks. The specific trialkyl benzyl ammonium salts, (benzyl) dimethyl tetradecyl ammonium salt (alkyl sulfonate salts, acetate salts, halides, etc.), (benzyl)
Dimethyl dodecyl ammonium salt, (benzyl) dimethyl octadecyl ammonium salt, (benzyl) dimethyl decyl ammonium salt, (benzyl) diethyl octyl ammonium salt, ((trifluoromethyl) phenylmethyl) dimethyl dodecyl ammonium salt, (benzyl) ethyl methyl octadecyl ammonium salt Salt, (monochlorophenylmethyl) dimethylhexadecyl ammonium salt and the like. The aromatic sulfonic acids mentioned above include benzenesulfonic acid, naphthalenesulfonic acid, and salts thereof. Specifically, 1,2-dihydroxybenzenesulfonic acid, mono-t-butylnaphthalenesulfonic acid, 2-hydroxynaphthalenesulfonic acid, 1,3-dihydroxybenzenesulfonic acid salt, diamylnaphthalenesulfonic acid salt, tri-isopropyl Naphthalene sulfonate, 1,
Examples thereof include 2-dihydroxynaphthalene sulfonate and 1,8-dihydroxynaphthalene sulfonate.

Further, various additives such as brighteners such as p-chlorobenzaldehyde, 1-naphthaldehyde and benzylideneacetone, semi-brighteners such as thiourea and benzothiazole, or smoothing agents are added to the plating bath. May be.

The factors of the plating conditions are: cathode current density, plating bath temperature, plating bath agitation degree, plating time,
The plating film thickness, applied voltage waveform, energized current waveform, etc. may be mentioned.

Specifically, the surface coating material is a lead or electrode of an electronic component such as a semiconductor device, a connector, a resistor, a capacitor, an inductor, or a hoop material.

[0025]

EFFECTS OF THE INVENTION β-tin has a body-centered tetragonal crystal morphology, and the a-axis in the unit crystal lattice is 5.8317Å, while the c-axis is 3.1815Å. It can be estimated that the directionality is strong. That is, the plastic deformation of the β-tin crystal occurs when a predetermined crystal plane in the lattice shifts, and particularly when the {110} plane of the Miller index or the like slides along the <001> direction. Conceivable. Usually when bending leads of electronic parts
For example, in the lateral direction parallel to the base metal surface of the lead.
Being susceptible to external force, <001> of β-tin crystal lattice
The direction is 9 with respect to the external force direction parallel to the surface of the base metal.
When the preferred orientation is 0 to 35 degrees, the <001> direction, which is also the sliding direction of the β-tin crystal, forms a high angle with respect to this external force direction, so that the plating film is directed in the direction along this external force. It becomes difficult to plastically deform. In other words, as described above, when bending the leads of electronic parts with a mold, the direction parallel to the surface of the base metal of the leads immediately becomes
Therefore, if the β-tin crystal is oriented under a specific condition in relation to the external force direction as in the present invention 1 or 2 , even if mechanical processing is performed, plastic deformation of the plating film is generated in the processing direction. And the amount of shavings of the tin or tin-lead alloy plating film can be suppressed to a low level.

[0026]

That is, regarding the shavings of the plating film generated during the machining of the surface coating material, there has been no technical idea of controlling the orientation of tin in the past. It was possible to newly develop a highly effective technique capable of reducing the amount of shavings by a simple and clear means of controlling the crystal orientation.

[0028]

EXAMPLES Examples of various plating baths and electroplating will be described below, together with an example of shavings generation test of the obtained tin and tin-lead alloy electrodeposition coating. However, the present invention is not limited to the following examples.

Example 1 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead methanesulfonate (as Pb ²⁺ ) 4.2 g / l Free methanesulfonate 200 g / l Octadecyl alcohol polyethoxylate (EO20) 10 g / l Dodecylamine polyethoxylate (EO15) -polypropoxylate (PO3) 3 g / l (benzyl) dimethyltetradecyl ammonium chloride 3 g / l mono-t-butylnaphthalene sulfonic acid 0.5 g / l catechol 2 g / l

The plating bath is an organic sulfonic acid bath containing soluble salts of tin and lead, two kinds of nonionic surfactants, and a specific trialkylbenzylammonium salt.
It is a mixture of an aromatic sulfonic acid and an antioxidant (for preventing the oxidation of stannous ions). Using the above plating bath, electroplating was performed on the surface of the base metal made of 42 alloy in the size of 25 × 25 × 0.2 mm under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 35 ° C. or less, and the size and material of the base metal are the same in Examples 2 to 19 and Comparative Examples 1 to 8.

The resulting tin-lead alloy plating film had a thickness of about 10
It had a film thickness of μm and a lead content of about 10%. still,
In Examples 2 to 19 and Comparative Examples 1 to 8 described later, 10 ± 1
In order to satisfy the film thickness condition of μm, and in Examples 1-12 and Comparative Examples 1 to 4 of tin-lead alloy plating, 10 ±
Each plating film was formed so as to satisfy the lead content condition of 0.5%.

Then, the orientation of β-tin crystals in the tin-lead alloy plating film was examined by an X-ray diffraction method. In the diffraction method, the diffraction peak height of each crystal face of β-tin was obtained from the X-ray diffraction pattern, and the orientation index X _hkl of each crystal face was calculated by the following formula (A) (the calculation formula is metal Surface Technology Association 76th Lecture Meeting Abstracts No. 200-20
See page 1 (1987)). X _hkl = {(ΣASTM I / I ₁ ) × (measured (hkl) plane I / I ₁ )} ÷ {(Σ measured I / I ₁ ) × (ASTM (hkl) plane I / I ₁ ) × I ₁ )} (A) X _hkl in formula (A): orientation index of (hkl) plane I / I ₁ : diffraction intensity of (hkl) plane / diffraction of strongest diffraction peak in X-ray diffraction pattern Strength Σ ASTM I / I ₁ : Standard ASTM card I
/ I ₁ sum Σ Measured I / I ₁ : Sum of actually measured I / I ₁ , that is, in the measured X-ray diffraction diagram, diffraction peaks with different intensities appear for each crystal plane, The diffraction peak I of each crystal plane is divided by its maximum peak I ₁ to obtain I / I of each (hkl) plane.
I ₁ or I / I ₁ measured by Σ was determined, and corresponding values in the standard ASTM pattern of the ASTM card were determined to calculate the orientation index X _hkl .

In this case, the crystal plane having the highest numerical value in the orientation index becomes the preferential orientation plane and is statistically parallel to the surface of the base metal.

On the other hand, in the β-tin crystal lattice, the angle between the preferential orientation plane and the <001> direction is uniquely determined in space, so that the preferential orientation plane parallel to the surface of the base metal is specifically When it is found, the angle θ formed by this <001> direction with respect to the normal direction standing on the surface of the base metal can be easily determined. In other words, the crystal orientation of β-tin is quantitatively expressed by using the angle θ between the <001> direction and the normal to the surface of the base metal, instead of the crystal plane of the preferential orientation plane. You can do it. As a result, in the plating film of Example 1, the <001> direction of the β-tin crystal was observed.
It has been confirmed that is preferentially oriented at the following angle θ with respect to the normal direction of the surface of the base metal . θ = 28.6 degrees The angle θ of Examples 2 to 19 and Comparative Examples 1 to 8 described later
Indicates the angle formed by the <001> direction with respect to the normal to the surface of the base metal.

Example 2 A tin-lead alloy plating bath was constructed with the following composition. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 46.5 g / l Lead 2-propanol sulfonate (as Pb ²⁺ ) 3.5 g / l Free methane sulfonic acid 140 g / l Nonylphenol polyethoxylate (EO13) 10 g / l nonylamine polyethoxylate (EO15) -polypropoxylate (PO2) 3 g / l (benzyl) dimethyldodecyl ammonium methyl sulfonate 3 g / l sodium diamylnaphthalene sulfonate 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the base metal made of 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. Then, in the same manner as in Example 1 above, the orientation of β-tin crystals in the obtained tin-lead alloy plating film was examined by X-ray diffraction, and orientation was performed. The following angle θ was obtained based on the crystal plane having the highest sex index. θ = 28.6 degrees

Example 3 A tin-lead alloy plating bath was constructed with the following composition. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 46.5 g / l Lead 2-propanol sulfonate (as Pb ²⁺ ) 3.5 g / l Free methane sulfonic acid 140 g / l Nonylphenol polyethoxylate (EO13) 10 g / l nonylamine polyethoxylate (EO15) -polypropoxylate (PO2) 3 g / l (benzyl) dimethyldodecyl ammonium methyl sulfonate 3 g / l sodium diamylnaphthalene sulfonate 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the base metal made of the 42 alloy under the following conditions. Cathode current density: 7 A / dm ² Bath temperature: 35 ° C. and β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 21.1 degrees

Example 4 A tin-lead alloy plating bath was constructed with the following composition. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 46.5 g / l Lead 2-propanol sulfonate (as Pb ²⁺ ) 3.5 g / l Free methane sulfonic acid 140 g / l Nonylphenol polyethoxylate (EO13) 10 g / l nonylamine polyethoxylate (EO15) -polypropoxylate (PO2) 3 g / l (benzyl) dimethyldodecyl ammonium methyl sulfonate 3 g / l sodium diamylnaphthalene sulfonate 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the base metal surface of the 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 35 ° C. and β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 50.7 degrees

Example 5 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead 2-propanol sulfonate (as Pb ²⁺ ) 4.2 g / l Free 2-propanol sulfonate 140 g / l Octylphenol polyethoxylate (EO12) -Polypropoxylate (PO4) 10 g / l decylamine polyethoxylate (EO15) -polypropoxylate (PO4) 2 g / l (benzyl) diethyloctyl ammonium bromide 3 g / l potassium tri-isopropylnaphthalene sulfonate 1 g / l catechol 2 g / L

Using the above plating bath, electroplating was performed on the surface of the base metal made of 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. And β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 21.1 degrees

Example 6 A tin-lead alloy plating bath was constructed with the following composition. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 46.5 g / l Lead methanesulfonate (as Pb ²⁺ ) 3.5 g / l Free 2-propanol sulfonate 140 g / l Nonylphenol polyethoxylate (EO30) 10 g / l dodecylamine polyethoxylate (EO8) -polypropoxylate (PO3) 2 g / l ((trifluoromethyl) phenylmethyl) dimethyldodecyl-ammonium acetate 3 g / l 2-hydroxynaphthalenesulfonic acid 2 g / l hydroquinone 2 g / l l

Using the above plating bath, electroplating was performed on the base metal surface made of the 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. And β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 21.1 degrees

Example 7 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 46.5 g / l Lead methanesulfonate (as Pb ²⁺ ) 3.5 g / l Free methanesulfonate 180 g / l Octadecyl alcohol polyethoxylate (EO30) 10 g / l Octylamine polyethoxylate (EO6) -polypropoxylate (PO4) 3g / l (benzyl) ethylmethyloctadecyl-ammonium methyl sulfonate 3g / l 1,2-dihydroxynaphthalene sodium sulfonate 1g / l catechol 2g / l

Using the above-mentioned plating bath, electroplating was performed on the surface of the base metal made of copper alloy (the size is the same as in Example 1; the same applies to the following Examples and Comparative Examples) under the following conditions. did. Cathode current density: 12 A / dm ² Bath temperature: 40 ° C. And β-in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 40.8 degrees

Example 8 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead methanesulfonate (as Pb ²⁺ ) 4.2 g / l Free methanesulfonate 160 g / l Naphthol polyethoxylate (EO20) 10 g / l Dodecyl Amine polyethoxylate (EO8) -polypropoxylate (PO2) 3 g / l (benzyl) dimethyloctadecyl ammonium chloride 3 g / l 1,8-dihydroxynaphthalene sulfonic acid sodium salt 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 17 A / dm ² Bath temperature: 40 ° C. And β-in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 28.6 degrees

Example 9 A tin-lead alloy plating bath having the following composition was constructed. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 27 g / l Lead 2-propanol sulfonate (as Pb ²⁺ ) 3 g / l Free methanesulfonate 120 g / l Naphthol polyethoxylate (EO30) 10 g / l Nonyl Amine polyethoxylate (EO30) -polypropoxylate (PO6) 3 g / l (monochlorophenylmethyl) dimethylhexadecyl-ammonium chloride 3 g / l 1,2-dihydroxybenzenesulfonic acid 0.5 g / l catechol 2 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 7 A / dm ² Bath temperature: 30 ° C and β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 50.7 degrees

Example 10 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead 2-propanol sulfonate (as Pb ²⁺ ) 4.2 g / l Free 2-propanol sulfonate 200 g / l Octylphenol polyethoxylate (EO30) -Polypropoxylate (PO4) 10 g / l decylamine polyethoxylate (EO30) -polypropoxylate (PO4) 2 g / l (benzyl) dimethyldecyl ammonium bromide 3 g / l sodium 1,3-dihydroxybenzenesulfonate 1 g / l Hydroquinone 2g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 20 A / dm ² Bath temperature: 40 ° C. And β-in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 21.1 degrees

Example 11 A tin-lead alloy plating bath having the following composition was constructed. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 19.3 g / l Lead methanesulfonate (as Pb ²⁺ ) 0.7 g / l Free 2-propanol sulfonate 100 g / l Benzylphenol polyethoxylate (EO10) ) 10 g / l 2-mercaptobenzothiazole 0.3 g / l catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 2 A / dm ² Bath temperature: 25 ° C. and β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 21.1 degrees

Example 12 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 19 g / l Lead methanesulfonate (as Pb ²⁺ ) 1 g / l Free methanesulfonate 100 g / l Naphthol polyethoxylate (EO10) 10 g / l Octylamine polyethoxylate (EO14) -polypropoxylate (PO4) 3 g / l 2-mercaptobenzothiazole 0.4 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 2 A / dm ² Bath temperature: 25 ° C. and β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 28.6 degrees

Example 13 A tin plating bath having the following composition was set up. Stannous 2-propanol (as Sn ²⁺ ) 60 g / l Free methanesulfonic acid 140 g / l Nonylphenol polyethoxylate (EO10) 10 g / l Nonylamine polyethoxylate (EO12) -Polypropoxylate (PO2) 3 g / L (benzyl) dimethyl dodecyl ammonium methyl sulfonate 2 g / l sodium diamylnaphthalene sulfonate 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the base metal surface made of the 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. Then, the orientation of β-tin crystal in the obtained tin plating film was examined by X-ray diffraction method, and the following angle θ was obtained. θ = 21.1 degrees

Example 14 A tin plating bath having the following composition was constructed. Stannous 2-propanol (as Sn ²⁺ ) 60 g / l Free methanesulfonic acid 140 g / l Nonylphenol polyethoxylate (EO10) 10 g / l Nonylamine polyethoxylate (EO12) -Polypropoxylate (PO2) 3 g / L (benzyl) dimethyl dodecyl ammonium methyl sulfonate 2 g / l sodium diamylnaphthalene sulfonate 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the base metal surface made of the 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 35 ° C. Then, the orientation of β-tin crystal in the obtained tin plating film was examined by X-ray diffraction method, and the following angle θ was obtained. θ = 50.7 degrees

Example 15 A tin plating bath having the following composition was constructed. Stannous 2-propanol (as Sn ²⁺ ) 60 g / l Free methanesulfonic acid 140 g / l Nonylphenol polyethoxylate (EO10) 10 g / l Nonylamine polyethoxylate (EO12) -Polypropoxylate (PO2) 3 g / L (benzyl) dimethyl dodecyl ammonium methyl sulfonate 2 g / l sodium diamylnaphthalene sulfonate 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the base metal surface made of the 42 alloy under the following conditions. Cathode current density: 7 A / dm ² Bath temperature: 35 ° C. Then, the orientation of β-tin crystals in the obtained tin-plated film was examined by an X-ray diffraction method, and the following angle θ was obtained. θ = 28.6 degrees

Example 16 A tin plating bath having the following composition was constructed. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 60 g / l Free 2-propanol sulfonate 140 g / l Nonylphenol polyethoxylate (EO28) 10 g / l Dodecylamine polyethoxylate (EO8) -Polypropoxylate (PO2) ) 2 g / l ((trifluoromethyl) phenylmethyl) dimethyldodecyl-ammonium acetate 3 g / l sodium diamylnaphthalene sulfonate 2 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. Then, the orientation of β-tin crystal in the obtained tin plating film was examined by X-ray diffraction method, and the following angle θ was obtained. θ = 40.8 degrees

Example 17 A tin plating bath having the following composition was set up. Stannous methanesulfonate (as Sn ²⁺ ) 60 g / l Free methanesulfonic acid 160 g / l Naphthol polyethoxylate (EO20) 10 g / l Dodecylamine polyethoxylate (EO8) -Polypropoxylate (PO2) 3 g / l (Benzyl) dimethyl octadecyl ammonium chloride 3 g / l 1,8-dihydroxynaphthalene sodium sulfonate 0.5 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 17 A / dm ² Bath temperature: 40 ° C. Then, the orientation of β-tin crystals in the obtained tin-plated film was examined by an X-ray diffraction method, and the following angle θ was obtained. θ = 50.7 degrees

Example 18 A tin plating bath having the following composition was set up. Stannous methanesulfonate (as Sn ²⁺ ) 60 g / l Free 2-propanol sulfonic acid 200 g / l Octylphenol polyethoxylate (EO30) -Polypropoxylate (PO4) 10 g / l Decylamine polyethoxylate (EO30)- Polypropoxylate (PO4) 2 g / l (benzyl) dimethyldecylammonium bromide 3 g / l Sodium 1,3-dihydroxybenzenesulfonate 1 g / l Hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 13 A / dm ² Bath temperature: 35 ° C. Then, the orientation of β-tin crystal in the obtained tin plating film was examined by X-ray diffraction method, and the following angle θ was obtained. θ = 28.6 degrees

Example 19 A tin plating bath having the following composition was set up. Stannous methanesulfonate (as Sn ²⁺ ) 20 g / l Free methanesulfonic acid 100 g / l Naphthol polyethoxylate (EO10) 10 g / l Octylamine polyethoxylate (EO14) -polypropoxylate (PO4) 3 g / l 2-mercaptobenzothiazole 0.4 g / l hydroquinone 2 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 2 A / dm ² Bath temperature: 25 ° C. Then, the orientation of β-tin crystals in the obtained tin-plated film was examined by an X-ray diffraction method, and the following angle θ was obtained. θ = 28.6 degrees

Comparative Example 1 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead methanesulfonate (as Pb ²⁺ ) 4.2 g / l Free methanesulfonate 140 g / l Styrenated phenol polyethoxylate (EO23) 8 g / 1 Pluronic polyethoxylate (EO26) -polypropoxylate (PO30) 2 g / l sodium dodecylbenzenesulfonate 0.5 g / l Catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the base metal made of the 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. And β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 58.6 degrees

Comparative Example 2 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead methanesulfonate (as Pb ²⁺ ) 4.2 g / l Free methanesulfonate 140 g / l Styrenated phenol polyethoxylate (EO23) 8 g / 1 Pluronic polyethoxylate (EO26) -polypropoxylate (PO30) 2 g / l sodium dodecylbenzenesulfonate 0.5 g / l Catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the base metal made of the 42 alloy under the following conditions. Cathode current density: 20 A / dm ² Bath temperature: 45 ° C. And β-in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 58.6 degrees

Comparative Example 3 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead methanesulfonate (as Pb ²⁺ ) 4.2 g / l Free methanesulfonic acid 140 g / l Styrenated phenol polyethoxylate (EO14) 10 g / Pluronic polyethoxylate (EO18) -polypropoxylate (PO4) 1.5 g / l Sodium dodecylbenzenesulfonate 0.5 g / l Catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. And β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 90 degrees

Comparative Example 4 A tin-lead alloy plating bath was constructed with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Lead methanesulfonate (as Pb ²⁺ ) 4.2 g / l Free methanesulfonic acid 140 g / l Styrenated phenol polyethoxylate (EO14) 10 g / Pluronic polyethoxylate (EO18) -polypropoxylate (PO4) 1.5 g / l Sodium dodecylbenzenesulfonate 0.5 g / l Catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 35 ° C. and β- in the obtained tin-lead alloy plating film
The orientation of the tin crystal was examined by X-ray diffraction, and the following angle θ was obtained. θ = 90 degrees

Comparative Example 5 A tin plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 60 g / l Free methanesulfonic acid 140 g / l Styrenated phenol polyethoxylate (EO23) 8 g / l Pluronic polyethoxylate (EO26) -Polypropoxylate (PO30) 2 g / l Sodium dodecylbenzenesulfonate 0.5 g / l Catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the base metal made of the 42 alloy under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. Then, the orientation of β-tin crystal in the obtained tin plating film was examined by X-ray diffraction method, and the following angle θ was obtained. θ = 58.6 degrees

Comparative Example 6 A tin plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 60 g / l Free methanesulfonic acid 140 g / l Styrenated phenol polyethoxylate (EO23) 8 g / l Pluronic polyethoxylate (EO26) -Polypropoxylate (PO30) 2 g / l Sodium dodecylbenzenesulfonate 0.5 g / l Catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the base metal made of the 42 alloy under the following conditions. Cathode current density: 20 A / dm ² Bath temperature: 45 ° C. Then, the orientation of β-tin crystals in the obtained tin-plated film was examined by an X-ray diffraction method, and the following angle θ was obtained. θ = 58.6 degrees

Comparative Example 7 A tin plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 60 g / l Free methanesulfonic acid 140 g / l Styrenated phenol polyethoxylates (EO14) 10 g / l Pluronic polyethoxylates (EO18) -polypropoxylates (PO4) 1. 5 g / l sodium dodecylbenzene sulfonate 0.5 g / l catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 40 ° C. Then, the orientation of β-tin crystal in the obtained tin plating film was examined by X-ray diffraction method, and the following angle θ was obtained. θ = 90 degrees

Comparative Example 8 A tin plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 55.8 g / l Free methanesulfonic acid 140 g / l Styrenated phenol polyethoxylates (EO23) 10 g / l Pluronic polyethoxylates (EO18) -polypropoxylates (PO4) 1.5 g / l sodium dodecylbenzenesulfonate 0.5 g / l catechol 1 g / l

Using the above plating bath, electroplating was performed on the surface of the copper alloy base metal under the following conditions. Cathode current density: 15 A / dm ² Bath temperature: 35 ° C. Then, the orientation of β-tin crystal in the obtained tin plating film was examined by X-ray diffraction method, and the following angle θ was obtained. θ = 90 degrees

Examples 1 to 19 and Comparative Examples 1 to 8
Then, it was described how the <001> direction of the crystal lattice was oriented at an angle θ with respect to the normal direction of the surface of the base metal due to changes in the composition of the plating bath and the plating conditions.
In the following, the <001> direction is formed with respect to the surface of the base metal.
The angle α (= 90 ° −θ) was replaced, and the orientation evaluation of the β-tin crystal was summarized.

<< Assessment of Orientation of β-Tin Crystals >> When tin-lead alloy plating films are compared with Examples 1 and 2 and 8 and 12, even if the compositions of the plating baths are different, the cathode current density and the bath are different. By controlling the temperature plating conditions, the β-tin crystals in the plating film have the same orientation (both
It can be seen that θ = 28.6 degrees , that is, α = 61.4 degrees ) is obtained. This is the same as the relationship between Examples 15 and 18 and 19 in the tin plating film. Conversely, tin-
Comparing Examples 2 and 3 and 4 in the lead alloy plating film, even if the composition of the plating bath is the same, the β-tin crystal of the plating film can be controlled by controlling the plating conditions such as the cathode current density and the bath temperature. It can be seen that each obtains a different orientation.
This means that the tin plating film of Examples 13 and 1
It is the same as the relationship between 4 and 15.

On the other hand, in the tin-lead alloy plating film, comparing Examples 2, 5, and 6 with Comparative Examples 1 and 3, the plating conditions of cathode current density and bath temperature (15 A / dm ²
It can be seen that the β-tin crystals of the plating film acquire different orientations by controlling the composition of the plating bath even at the same temperature of 40 ° C. and 40 ° C.). That is, in Examples 2, 5, and 6, θ
It was <55 degrees (ie, α> 35 degrees) , but in Comparative Examples 1 and 3, θ> 55 degrees (ie, α <35 degrees) . In particular, looking at Comparative Examples 1 and 3, even if the cathode current density and bath temperature were the same, the angle θ increased from 58.6 degrees (Comparative Example 1) to 90 degrees (Comparative Example 3) when the bath composition was slightly different. Changing
(The angle α is greatly reduced from 31.4 degrees to 0 degrees.
) . This means that in the tin plating film,
The relationship between Nos. 3 and 16 and Comparative Examples 5 and 7 is the same.

Incidentally, the above-mentioned Embodiments 2 and 4 (or Embodiment 1)
3 and 14), when the composition of the plating bath and the cathode current density are the same, when the bath temperature during electroplating is increased from 35 to 40 ° C., the angle θ is 50.7 to 28.6 degrees (or 50. 7
→ It turns out to decrease to 21.1 degrees (that is, <00
1) Replace with the angle α that the direction makes with the surface of the base metal
Then, from 39.3 degrees to 61.4 degrees, or 39.3 degrees
To 68.9 degrees) . In addition, the above-mentioned Examples 3 and 4
Comparing (or Examples 14 and 15), when the composition of the plating bath and the bath temperature are the same, when the cathode current density during electroplating is lowered to 15 → 7 A / dm ² , the angle θ is 50.7 → 2.
It can be seen that the angle decreases to 1.1 degrees (or 50.7 → 28.6 degrees) (that is, substituting the angle α from 39.3 degrees
Increased to 68.9 degrees or 69.3 degrees from 39.3 degrees
) .

From the above, it is practically possible to impart proper orientation to the β-tin crystal by controlling the composition of the plating bath and the plating conditions, but on the other hand, as described above, Since many factors exist between the composition and plating conditions of the plating bath and the orientation of the β-tin crystal of the obtained plating film, it is not easy to derive a general law.

<< Example of shavings generation test of plating film >> The surface coating materials of Examples 1 to 19 and Comparative Examples 1 to 8 were used as test pieces, and the surface of the tin or tin-lead alloy plating film of the test piece was tested. On the other hand, a vertical load of 300 gf is applied 3
A 0 mm diameter steel ball was pressed. Next, the steel ball was reciprocated 100 times in the horizontal direction at a speed of 50 mm / min on the surface of the plated film, and the film thickness of the wear mark was measured. Then, the degree of generation of shavings in the plating film was evaluated based on the amount of decrease in the film thickness from the original thickness.

The evaluation criteria for the amount of shavings generated are as follows. The smaller the film thickness reduction amount, the smaller the amount of shavings generated, and the higher the evaluation. 5 points: The amount of film thickness reduction is 1 μm or less. 4 points: The film thickness reduction amount is 1 to 2 μm. 3 points: The thickness reduction amount is 2 to 4 μm. 2 points: The amount of film thickness reduction is 4 to 8 μm. 1 point: The thickness reduction amount is 8 μm or more.

FIG. 1 shows the test results of the coating material of the tin-lead alloy plating film, and FIG. 2 shows the test results of the tin plating film. Examples 1 to 12 (tin-lead alloy plating film) were evaluated at 4 points each, and Examples 13 to 19 (tin plating film) were evaluated at 5 to 4 points respectively, while Comparative Examples 1 to 8 were evaluated.
The evaluation was low with 1 to 2 points, and the amount of film thickness reduction was large. That is, in the above Examples 1 to 19, the angle θ <55 degrees (angle
α> 35 degrees) , β-tin crystals of each plating film are preferentially oriented, but θ> 55 degrees (α <35 degrees)
By comparing the comparative examples 1 to 8 which are preferentially oriented in 1., the effect of suppressing the generation amount of shavings in these examples is clear.

Here, the angle θ is β as described above.
-The <001> direction of the tin crystal lattice is an angle formed with respect to the normal direction of the surface of the base metal , and the angle α is the above <00
The 1> direction is an angle formed with respect to the surface of the base metal. Further, in this test example, the direction of the external force applied by the steel balls is the horizontal direction along the surface of the plating film (that is, the surface of the base metal). Therefore, preferentially orienting the β-tin crystal under the condition of θ <55 degrees is expressed by the relation with the external force direction parallel to the surface of the base metal , <0 of the β-tin crystal lattice.
01> direction with respect to the external force direction α = 90 to 35 degrees
Is synonymous with forming a high angle and preferentially orienting.

[Brief description of drawings]

FIG. 1 is a table showing the results of a shaving generation test with each surface coating material of a tin-lead alloy plating film obtained from Examples 1 to 12 and Comparative Examples 1 to 4.

FIG. 2 is a table showing the results of a shaving generation test using tin coatings obtained in Examples 13 to 19 and Comparative Examples 5 to 8 with each surface coating material.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Takeuchi 8 21 Minami Futami, Futami-cho, Akashi-shi, Hyogo 8 Daiwa Kasei Laboratory Co., Ltd. (56) Reference JP-A-4-168292 (JP, A) JP-A 5-25689 (JP, A) JP-A-61-292350 (JP, A) JP-A-9-95794 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C25D 3/00 -7/12

Claims (7)

(57) [Claims] 1. A tin on base metal - the surface covering material covering by electroplating lead alloy plating film, the matrix
Β in the plating film with respect to the external force direction parallel to the metal surface
A surface coating material by tin-lead alloy plating, characterized in that the β-tin crystal is preferentially oriented so that the <001> direction of the Miller index in the tin crystal lattice forms a high angle of 90 to 35 degrees. . 2. A tin-plated film is electroplated on the base metal.
In the surface coating material coated by g
Parallel to the external force direction of β-tin in the plating film
The <001> direction of the Miller index in the crystal lattice is 90-
The β-tin crystal is excelled so as to form a high angle of 35 degrees.
A surface coating material by tin plating , characterized by being orientated first . 3. The surface coating material according to claim 1, wherein the content of lead in the tin-lead alloy plating film is 20% or less. 4. The surface coating material by tin and tin-lead alloy plating according to claim 1, wherein the plating film has a thickness of 1 to 30 μm. 5. A base metal is electroplated with a plating bath containing a soluble salt of tin or a soluble salt of tin and lead, an organic sulfonic acid, and a surfactant as main components. The surface coating material by the tin and tin-lead alloy plating according to any one of claims 1 to 4. 6. An electronic component, wherein the lead and the electrode are the surface coating material according to any one of claims 1 to 5. 7. The electronic component according to claim 6 semiconductor Device
Characterized by being a chair or connector .