JP2005144895A - Colored, surface-treated stainless steel plate and box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a colored, surface-treated stainless steel plate excellent in solder wettability, and heat radiation properties and a box. <P>SOLUTION: A colored, surface-treated membrane below 10 s in solder wettability by a meniscographic method is formed on a plated stainless steel plate in which nickel strike plating and nickel plating are formed on a substrate of a stainless steel plate. A heat radiation rate is 0.1-0.9. The colored, surface-treated membrane is formed by applying an aqueous acrylic resin containing a colored pigment and an aqueous urethane resin or the colored pigment and rosin and drying the applied resin to make the colored, surface-treated stainless steel plate which is applied to various boxes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a colored surface-treated stainless steel sheet obtained by forming a colored surface-treated film excellent in solderability, corrosion resistance, and thermal radiation on a plated stainless steel sheet, and a housing using the same.

  In recent years, in surface-treated metal plates applied to various housing applications such as metal containers, home appliance chassis, cabinets, electronic component substrates, steel plates as substrates, achromatic colors such as black, white, gray, etc. from a decorative point of view, A colored surface-treated steel sheet is used in which a surface-treated film colored in colors such as red, blue, yellow, green, brown, pink is formed on a steel sheet. The surface-treated steel sheet used for these applications may be subjected to soldering for bonding with other parts or members where it needs to be bonded after being molded into a predetermined shape. In the treated steel sheet, the soldered wettability of the colored colored surface treatment film was poor, and it could not be applied to applications requiring soldering.

  In particular, in the case of a housing for an electronic component board, it is necessary to suppress the temperature rise of a component loaded in a narrow housing or with almost no gap as the electronic device is miniaturized and densified. Has occurred. For this reason, a material having heat dissipation is required for use in a housing. In addition, as electronic devices become smaller and higher in density, it is also required to reduce the weight of the housing material, so that even a thin thickness is sufficient for applications that require high strength. Stainless steel plate that has excellent strength and does not cause rust on the cut end face is used, but stainless steel plate has poor solder wettability and cannot be applied to applications that require soldering. It was.

  As a conventional technology for steel sheets with excellent solder wettability, tin plating is applied to the steel sheet, and then the plating mainly containing at least one of zinc, nickel, and cobalt, or zinc, nickel, cobalt on the tin plating. A two-layer plated steel sheet for solder, which contains any one or more of tin, iron, lead, and copper and is plated with an alloy having a lower potential than the standard electrode potential of tin. It is disclosed (for example, see Patent Document 1). Since this plated steel sheet does not have a protective coating layer with excellent corrosion resistance like a chromate-treated film, the corrosion resistance is not sufficient, and the formation of a corrosion product film may also deteriorate the solder wettability. .

  In addition, an Sn—Zn alloy layer is formed on a surface-treated steel sheet in which a Sn—Zn alloy layer is formed on the steel plate, or a surface treatment layer made of either Ni plating or Fe—Ni diffusion layer is formed on the surface. An environmentally-friendly surface-treated steel sheet for electronic components in which an inorganic film mainly composed of magnesium phosphate is formed on a Sn—Zn alloy layer is disclosed (for example, see Patent Document 2). This inorganic film mainly composed of magnesium phosphate can also give high corrosion resistance to the Sn—Zn alloy, but due to its stability, particularly when a weakly active or inactive flux containing no chlorine is used. It has a drawback of poor solderability.

  Furthermore, since these two-layer plated steel sheets for solder and surface-treated steel sheets for electronic components use steel sheets as substrates for forming surface-treated films, the steel is exposed at the cut surface, so that red rust is likely to occur. Have.

  Prior art document information relating to the present application includes the following.

JP-A 63-277786 Japanese Patent Laid-Open No. 2002-249885

  An object of the present invention is to provide a colored surface-treated stainless steel sheet and a casing having excellent solder wettability, corrosion resistance, and excellent heat radiation.

In order to solve the above-mentioned problems, the colored surface-treated stainless steel sheet of the present invention is formed by forming a colored surface-treated film having a solder wettability of less than 10 seconds by a meniscograph method on a plated stainless steel sheet and having a thermal emissivity of 0. .1 to 0.9,
In the colored surface-treated metal plate according to (Claim 1), the plated stainless steel plate is formed by sequentially forming nickel strike plating and nickel plating from the substrate side on the substrate made of stainless steel plate (Claim 2), Alternatively, the plated stainless steel plate is formed by sequentially forming nickel strike plating, nickel plating, and tin plating from the substrate side on a substrate made of a stainless steel plate. (Claim 3)
In the colored surface-treated stainless steel sheet of the above (Claims 1 to 3), the colored surface-treated film is a film formed by applying a colored pigment and an aqueous urethane resin and drying (Claim 4), or The colored surface treatment film is a film formed by applying and drying a water-based acrylic resin containing a color pigment and rosin (Claim 5), and further characterized by the above (Claim 4 or 5). In the metal plate, the color pigment is a black pigment (claim 6).

  And the housing | casing of this invention is a housing | casing (Claim 7) formed using the colored surface-treated stainless steel plate of said (Claims 1-6).

  In the present invention, a stainless steel plate excellent in strength and corrosion resistance is used as a substrate, and a plated urethane steel plate formed by applying a plating layer having solder wettability as well as excellent adhesion to the substrate, a water-based urethane resin excellent in solder wettability and Since water-based acrylic resin containing water-solubilized rosin is further coated with achromatic or chromatic coloring pigments and dried to form a colored surface treatment film, solder wettability by the meniscograph method is less than 10 seconds Excellent solder wettability, and excellent thermal emissivity of 0.1 to 0.9, vivid colors and excellent decorativeness. Therefore, it can be suitably applied as a thin-walled electronic device casing or electronic component substrate that requires excellent corrosion resistance, solderability, and thermal radiation.

  Hereinafter, the present invention will be described in detail by embodiments.

Examples of the stainless steel plate used as the plating substrate include martensitic stainless steel plates such as JIS standards SUS410, 416, 420, 431, and 440, ferritic stainless steel plates such as SUS405, 430, and 434, SUS301, 304, 309, 310, and 316. , 321, 329, 347, etc. Any stainless steel plate can be used. After these stainless steel sheets are subjected to normal degreasing and pickling pretreatments, strike nickel plating is performed using a wood bath or the like in order to improve the adhesion of nickel plating on the stainless steel sheets. The thickness of the strike nickel plating is preferably 0.05 to 1.0 g / m ² in terms of the coating amount. Becomes poor adhesion of the nickel plating is less than 0.05 g / m ² for stainless steel, even exceeding 1.0 g / m ² and saturated the effect of improving adhesion of the nickel plating, would not be cost-effective .

Subsequently, a nickel plating is formed on the strike nickel plating. Nickel plating may be formed using either electroplating or electroless plating, but since strike nickel plating is performed by electrolysis in advance, it should be performed by electroplating using a watt bath or the like. Is preferred. The thickness of the nickel plating is preferably 0.2 to 50 g / m ² in terms of the coating amount. If it is less than 0.2 g / m ² , sufficient solder strength cannot be obtained. On the other hand, if the coating amount exceeds 50 g / m ² , the effect of improving the solder wettability and the solder strength is saturated, which is not advantageous in terms of cost.

Further, solder wettability can be further improved by further forming tin plating on the nickel plating. The tin plating is preferably performed by an electrolytic plating method using a ferrostan bath or a halogen bath. The thickness of the tin plating is preferably 1 to ²⁰ g / m ² in terms of the coating amount. If it is less than 1 g / m ² , the effect of improving the solder wettability is insufficient. On the other hand, if the coating amount exceeds 20 g / m ² , the effect of improving the solder wettability is saturated, which is not advantageous in terms of cost.

  Thus, a plated stainless steel plate excellent in solderability is obtained by forming nickel plating or nickel plating and tin plating on the stainless steel plate via strike nickel plating.

  The plated stainless steel sheet obtained as described above does not rust on the cut end face even if it is cut, has excellent corrosion resistance, and further forms a tin plating on the nickel plating or nickel plating as described above. Therefore, it is excellent in solderability and can be suitably applied to housing applications such as home appliance chassis and cabinets. Moreover, a thermal emissivity can be improved to about 0.1-0.9 by forming the colored surface treatment film | membrane which improves the thermal radiation property shown below. The colored surface-treated film that improves thermal radiation is formed on the plated stainless steel sheet as follows.

  As the resin constituting the film, it is preferable to use a water-based acrylic resin containing a water-based urethane resin or a water-soluble rosin. The concentration of these aqueous resins is preferably in the range of 100 to 900 g / L. A water-based acrylic resin containing these water-based urethane resin or water-soluble rosin is mixed with a color pigment, applied onto the plated metal plate, and dried to form a colored surface-treated film. Both organic and inorganic pigments can be applied, and one or more pigments of achromatic colors such as black and white, red, blue and yellow can be added to develop the desired color. Let When importance is attached to thermal radiation, it is preferable to use a black pigment. The amount added to the resin is preferably 1 to 50% by weight based on the solid content of the resin. If the content is less than 1% by weight, the vividness of the color tone is poor depending on the color, and if it exceeds 50% by weight, the solderability becomes poor. A more preferable addition amount is 3 to 30% by weight. Further, a colored ceramic powder may be used instead of the pigment. As the colored ceramic powder, it is preferable to use titanium carbide, titanium nitride, titanium boride, tungsten carbide, molybdenum nitride and a mixed powder obtained by mixing two or more of these ceramic powders.

  The water-soluble rosin contained in the water-based acrylic resin is a rosin soap obtained by neutralizing the carboxylic acid group in the abietic acid molecule, which is the main component of rosin, with an amine salt, etc. In order to improve solder wettability, it is contained in an aqueous acrylic resin. It is preferable to add in the range of 50-600 g / L in an aqueous acrylic resin liquid. If it is less than 50 g / L, the solder wettability after aging is insufficient, and if it exceeds 600 g / L, the viscosity becomes high and gelation tends to be difficult.

  One of the resin liquids obtained as described above is applied to one side or both sides of the plated stainless steel plate. In this case, the coating film thickness may be changed on the front and back surfaces. As a coating method, a known method such as a dipping method, a roll coating method, a curtain flow coating method, or a spray coating method can be used. However, when performing double-sided coating, taking advantage of the fact that this treatment liquid is water-based, a method of performing coating by dipping and drawing in the subsequent step of the continuous plating step is easy and economical. After applying using any of these application methods, it is dried to form a colored surface-treated film on the plated metal plate to obtain a colored surface-treated metal plate. The film thickness after drying is preferably 0.05 to 10 μm. If the thickness of the film is less than 0.05 μm, a uniform colored appearance cannot be obtained, and fingerprints are easily attached when touched with fingers. If it exceeds 10 μm, these effects of improving heat dissipation are saturated and solder wettability is lowered, which is not preferable.

  The colored surface-treated stainless steel sheet of the present invention thus obtained preferably has a solder wettability of less than 10 seconds according to the meniscograph method (MIL-STD-883B) shown below. When the solder wettability by the meniscograph method exceeds 10 seconds, the heated and melted solder does not spread sufficiently on the surface of the colored surface-treated metal plate, and sufficient adhesive strength with the mating material to be soldered cannot be obtained. The measurement of solder wettability by the meniscograph method is performed as follows. That is, using a SOLDERCHECKER (MODEL SAT-5000, manufactured by RHESCA), a 7 mm wide sample cut out from the above-mentioned colored surface-treated metal plate was immersed in a weakly active flux containing no chlorine, and then maintained at 250 ° C. A sample obtained by applying the above flux to (JIS Z 3282: H60A) is immersed for 2 mm at an immersion speed of 2 mm / second, and a zero cross time until the solder gets wet is measured to obtain solder wettability (seconds).

  Moreover, a thermal emissivity improves to 0.1-0.9 by forming a colored surface treatment film on a plated stainless steel plate to obtain a colored surface-treated stainless steel plate.

(Create test plate)
[Plated stainless steel sheet]
A stainless steel plate (JIS 304, plate thickness 0.2 mm) is used as a plating substrate, electrolytically degreased in an alkaline aqueous solution, then immersed in sulfuric acid, pickled, and then subjected to strike nickel plating under the conditions shown below using a wood bath. Subsequently, nickel plating was performed using a Watt bath under the conditions shown below to obtain a nickel-plated stainless steel sheet. Part of the nickel-plated stainless steel plate thus obtained was further subjected to tin plating using a ferrostan bath under the conditions shown below to obtain a nickel / tin-plated stainless steel plate.

<Strike nickel plating>
Bath composition Nickel chloride 240g / L
Hydrochloric acid 100mL / L
Bath temperature 50
Current density 5A / dm ²
Electrolysis time 7 seconds

<Nickel plating>
Bath composition Nickel sulfate 300g / L
Nickel chloride 45g /
Boric acid 45g /
Bath temperature 55 ° C
pH 3.0
Current density 5A / dm ²

<Tin plating>
Bath composition Stannous sulfate 30g / L
Phenolsulfonic acid 30g / L
Ethoxylated-α-naphthol 2g / L
Bath temperature 40 ℃
pH 2.0
Current density 5A / dm ²

  As described above, plated stainless steel sheets indicated by plating numbers A to E in Table 1 were prepared.

  Yellow, black, or red coloring pigments with the contents shown in Table 2 in water-based acrylic resins containing the water-based urethane resin or water-soluble rosin shown in Table 2 in the plated stainless steel sheets of these plating numbers A to E Or after apply | coating the resin liquid containing a titanium carbide using a dip and the squeezing method, it dried at the temperature of 90 degreeC, the sample of the sample numbers 1-10 was created, and the following characteristic evaluation was performed. Table 3 shows the evaluation results.

[Characteristic evaluation]
<Solder wettability>
Using SOLDERCHECKER (MODEL SAT-5000, manufactured by RHESCA), evaluation was carried out by the meniscograph method (MIL-STD-883B). That is, a specimen having a width of 7 mm was cut out from the samples of sample numbers 1 to 10, immersed in a weakly active flux (Lapix RMA, manufactured by Nippon Solder Industries) containing no chlorine as shown in Table 3, and then kept at 250 ° C. Specimens coated with the above flux in a solder bath (JIS Z 3282: H60A) are immersed 2 mm at an immersion speed of 2 mm / second, the time until the solder gets wet is measured, and the zero cross time is measured. evaluated. A shorter wetting time indicates better solderability. Note that the test was performed in two ways, immediately after sample preparation and at a constant temperature and humidity (60 ° C., 95% RH) for 500 hours. Except for ×, the acceptable range.
◎: Less than 5 seconds ○: Less than 5-7 seconds △: Less than 7-10 seconds ×: More than 10 seconds

[Characteristic evaluation]
<Solder strength>
Two specimens cut out from the samples of sample numbers 1 to 10 with a width of 7 mm and a length of 50 mm and bent into an L-shape are stacked so that the evaluation surfaces face each other in a T-shape. A test piece was prepared in which a 0.5 mm thick steel plate was sandwiched between the portions, and a 0.5 mm gap was formed below the T-shaped vertical bar. After applying the same flux as that used for the evaluation of the solder wettability to the void of the specimen, a solder bath (JIS Z) maintained at 250 ° C. using SOLDERCHECKER (MODEL SAT-5000, manufactured by RHESCA). 3282: H60A), the void portion of the specimen was dipped to a depth of 10 mm, held for 5 seconds, filled with solder in the void portion, and taken out to obtain a T peel specimen. Next, using Tensilon, the T-shaped horizontal bar part of the T-peel test piece is sandwiched and pulled, and the solder filling part of the T-shaped vertical bar part is peeled off to measure the solder strength. The strength was evaluated.
◎: 4 kgf / 7 mm or more ○: 3-4 kgf / 7 mm or less △: 1-3 kgf / 7 mm or less X: 1 kgf / 7 mm or less

<Plating adhesion>
A specimen was cut out with a width of 7 mm and a length of 50 mm from the samples of Sample Nos. 1 to 10, bent at 90 °, affixed scotch tape to the bent part (outside), and then peeled off. The plating adhesion was evaluated based on the following criteria.
○: No peeling is observed.
X: Peeling is recognized.

<Heat dissipation>
A specimen of 100 mm × 100 mm is cut out from the samples of sample numbers 1 to 10, and the thermal emissivity is measured using an emissivity meter (Dand S AERD emissivity meter, manufactured by Kyoto Electronics Industry Co., Ltd.). evaluated.
A: Thermal emissivity 0.5 to 0.9
○: Thermal emissivity 0.1 to less than 0.5 Δ: Thermal emissivity 0.05 to less than 0.1 ×: Thermal emissivity less than 0.05

<Color clarity>
Using the spectrocolorimeter (MODEL: CM-3500d, manufactured by Minolta Co., Ltd.) for the samples Nos. 1 to 10, the L value, the a value, and the b value were measured. Those within the range of the values are indicated by ○ as acceptance criteria. A value that deviated from the acceptance criteria was shown as x for failure.

  These characteristic evaluation results are shown in Table 3 above.

  The colored surface-treated stainless steel sheet of the present invention is excellent in corrosion resistance and, as shown in Table 3, has excellent solder wettability, high solder strength, and excellent heat dissipation. Moreover, it is excellent in color clarity as a colored stainless steel plate. Therefore, the colored surface-treated stainless steel plate of the present invention can be suitably applied as various housings having excellent heat dissipation that can be soldered.

  The colored surface-treated stainless steel sheet of the present invention is excellent in strength and corrosion resistance, so it does not rust on the cut end face, is excellent in solder wettability, has high solder strength, and is excellent in heat dissipation. Since it has excellent color clarity, it can be suitably applied to various housings such as thin and light electronic device housings that require solderability.

Claims (7)

  A colored surface-treated stainless steel characterized by forming a colored surface-treated film having a solder wettability by a meniscograph method of less than 10 seconds on a plated stainless steel plate and having a thermal emissivity of 0.1 to 0.9. steel sheet.   2. The colored surface-treated metal plate according to claim 1, wherein the plated stainless steel plate is formed by sequentially forming nickel strike plating and nickel plating from the substrate side on a substrate made of a stainless steel plate.   2. The colored surface-treated metal plate according to claim 1, wherein the plated stainless steel plate is formed by sequentially forming nickel strike plating, nickel plating, and tin plating from a substrate side on a substrate made of a stainless steel plate.   The colored surface-treated metal plate according to any one of claims 1 to 3, wherein the colored surface-treated film is a film formed by applying a colored pigment and a water-based urethane resin and drying.   The colored surface-treated metal plate according to any one of claims 1 to 3, wherein the colored surface-treated film is a film formed by applying and drying a water-based acrylic resin containing a color pigment and rosin. .   The colored surface-treated metal plate according to claim 4 or 5, wherein the colored pigment is a black pigment. A housing characterized in that it is formed using the colored surface-treated metal plate according to any one of claims 1 to 6.