JPS5834558B2 - Treatment method for anodic oxide film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating an anodic oxide film having high thermal conductivity, electrical insulation and heat resistance.

The anodic oxide film formed on metals such as aluminum, titanium, magnesium, and tantalum and their alloys is
It is a metal oxide film chemically formed on the surface of these metals, and is an electrically insulating film with a uniform structure, good adhesion to the base metal, and high corrosion resistance and thermal conductivity.

Utilizing the properties of this anodic oxide film, metals on which an anodized film has been formed are widely used in printed wiring boards for electronic devices, heat sinks for electronic components, insulated wires, building materials, etc.

When using anodic oxide films for these applications, the oxide film is formed thick to improve insulation and corrosion resistance, but many micropores inevitably occur in oxide films with a thickness of several microns or more. do.

These fine pores have a diameter of several hundred and nine and reach the barrier layer of the anodic oxide film.

For this reason, with a thick anodic oxide film, it has been impossible to obtain sufficiently high insulation and corrosion resistance due to moisture in the air and residual electrolyte during anodization.

In order to improve this drawback, a sealing treatment is sometimes performed in which the micropores are sealed with steam or boiling water, but when the pore sealing treatment is performed, the oxide film changes in water quality and is heated to around 150 degrees Celsius. This exposes the drawback that cracks appear in the anodic oxide film.

Moreover, when an unsealed anodic oxide film is heated to about 200'C, cracks occur in the oxide film.

This cracking occurs due to the large difference in coefficient of thermal expansion between the base metal and the oxide film, and cracks are generated due to thermal stress when heated.

In an anodic oxide film with cracks, moisture from the air enters into the cracks, resulting in a decrease in insulation and corrosion resistance.

This invention was made in view of the above circumstances, and aims to provide a method for treating an anodic oxide film that can form an anodic oxide film having high thermal conductivity, heat resistance, and electrical insulation. An anodic oxide film formed on a metal that can be anodized is heated to actively generate cracks, and then a polymerizable organometallic compound is impregnated into the micropores and cracks to polymerize and crack the anodic oxide film. The method is characterized in that the material is anodized again, and then a polymerizable organometallic compound is impregnated into the micropores and cracks and polymerized.

The present invention will be explained in detail below.

Examples of metals that can be anodized for use in the present invention include so-called valve metals such as aluminum, titanium, magnesium, and tantalum, and plates, bars, wires, and strips of alloys of these metals.

These metals are first anodized. This anodizing treatment is generally performed using an electrolytic bath such as an aqueous solution of sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, or chromic acid, as well as an alkaline bath or a molten bath. For example, direct current, AC/DC superimposed current, etc. are used.

Next, the metal on which the anodic oxide film has been formed is heated to cause cracks to occur in the oxide film.

This heating is carried out in a conventional heating furnace such as a Matsufuru furnace, and the heating temperature is higher than the temperature expected to be experienced by the product obtained by the treatment method of the present invention, and is generally 3.
00°C to 400°C is preferred.

Further, the heating time may be a time sufficient to sufficiently generate cracks in the oxide film, and 15 to 60 minutes is usually sufficient.

This heat treatment actively causes many heat cracks to occur in the anodic oxide film, and as long as the anodic oxide film is not exposed to temperatures higher than this heat treatment temperature, there will be no heat cracks in the anodic oxide film at all. It will no longer occur.

The anodic oxide film in which heat cracks have been generated in this way is then treated with a polymerizable organometallic compound, but if necessary, it may be anodized again and then treated with a polymerizable organometallic compound. be.

This re-anodization occurs due to heat treatment, and the base metal exposed in the cracks is anodized to form an oxide film.

Re-anodizing treatment is carried out under the normal conditions mentioned above,
The electrolysis time is short, and usually 5 to 10 minutes is sufficient.

In addition, the current density is 0.05 A/d m” to 1. O
A/dm is sufficient.

In this anodic oxidation, the electrolytic current concentrates on the exposed base metal portion of the cracked portion, and only the exposed base metal surface is selectively and effectively oxidized.

Next, the anodized film in which heat cracks have been generated or the anodized film that has been re-anodized is treated with a polymerizable organometallic compound.

The polymerizable organometallic compound used here is one in which a hydrolyzable organic group, a halogen group, and an organic functional group are bonded to a metal atom, and has polymerizability.

And general formula % formula % X: vinyl group, amino group, mercapto group, epoxy group,
Organic functional group R such as a methyl group or phenyl group: an organic metal compound represented by a hydrolyzable organic group such as an alkoxy group or an acetoxy group and a halogen group n+m=3.4.5 or 6, such as phenyltriethoxy Silane, methyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4
-Organosilicon compounds such as -epoxy-cyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, tetraisopropyl bis(dioctylphosphite) titanate, tetraoctylbis(ditridecylphosphite) titanate, titanium acetylacetate organic titanium compounds such as nate, titanium octylene glycolate, dihydroxybis(lactato)titanium, and tetrastearoxytitanium, organic aluminum compounds such as aluminum tri-n-butoxide, methylaluminum sesquichloride, aluminum triisopropoxide, and zirconium. tetra n-butoxide,
Organometallic compounds such as organic zirconium compounds such as zirconium tetraisopropoxide, derivatives and low polymers (oligomers) of these compounds are used.
Those having a methyl group and/or phenyl group in the organic functional group are preferable because they have a greater improvement in heat resistance.

Furthermore, it is better to use hydrolysis that occurs gradually.

These polymerizable organometallic compounds are used after being dissolved in an organic solvent such as methanol, ethanol, acetone, ethyl acetate, or methyl ethyl ketone, water, or a mixture of water and a water-soluble organic solvent.

Examples of water-soluble organic solvents used include methanol, ethanol, impropatul, acetone, dioxane, ethylene glycol, methyl acetate, methyl ethyl ketone, diacetone alcohol, ethyl formate, and dimethyl formamide, and if necessary, surfactant Additives such as agents can be added.

Then, the anodic oxide film is immersed in such a polymerizable organometallic compound solution to diffuse and penetrate the polymerizable organometallic compound into the micropores and cracks, or by using a vacuum impregnation method. .

Alternatively, the oxide film is immersed in a solution in which a polymerizable organometallic compound is dissolved in water or a mixture of water and a water-soluble organic solvent, and a direct current is applied using the oxide film as an anode and a suitable inert conductor as a cathode. By applying electricity, the polymerizable organometallic compound can be sufficiently impregnated from the bottom to the mouth of the micropores and cracks of the oxide film by electrophoresis, electroosmosis, or the like.

Once the micropores and cracks of the anodic oxide film are sufficiently impregnated with the polymerizable organometallic compound, the anodized film is dried to remove excess water and organic solvent.

The polymerizable organometallic compound thus impregnated into the micropores and cracks of the anodic oxide film is polymerized by a polymerization means such as heating.

Through this polymerization, the polymerizable organometallic compound becomes a dense organometallic compound polymer, and these organometallic compound polymers have a high affinity with the oxide film, so they firmly adhere to the micropores and cracks of the anodic oxide film and form fine particles. Holes and cracks will be effectively filled.

As described above, the anodized film treated with the polymerizable organometallic compound has very high electrical insulation properties because the micropores and cracks are completely filled with the organometallic compound polymer. Since the polymer is metal-based, the high thermal conductivity of the anodic oxide film is maintained.

Hereinafter, this invention will be specifically explained based on Examples.

[Example 1] A 2SAA plate measuring 50 m x 100 im x 1 mvt was anodized in an aqueous oxalic acid solution at a current density of 2 A/dm'' to obtain an anodic oxide film with a thickness of 30 μm.

This anodized film was heated in a Matsufuru furnace at 350° C. for 30 minutes to generate cracks.

Using this cracked anodic oxide film as an anode, phenyltriethoxysilane C6H55i (C2H50)
370vol 1%, ethanol 24vol 1%, acetic acid 4v
In a mixed solution of 1% O and 2 vol% water, electricity was applied at a constant DC of 150 V for 30 minutes to impregnate phenyltriethoxysilane into the micropores and cracks in the oxide film.

The current density at this time was initially 20 mA/dm,
The final value was 7 mA/d m'.

The solution adhering to the surface of the anodic oxide film was wiped off, dried with warm air, and then heated at 130° C. for 12 hours to polymerize.

A masking tape was pasted on the anodic oxide film surface of the aluminum substrate treated in this way, and 10im x 10mπ
Create many exposed parts of 5nC110,! 9/A' aqueous solution for 30 seconds, and then P d C
Activation treatment was performed for 10 minutes in a 7, 20, 5ji/1 aqueous solution, and then immersed in a commercially available Schumer electroless nickel plating solution at a bath temperature of 80°C for 1 minute to perform nickel plating.
A plating pattern of 0.010×10 was formed.

When the AC dielectric strength voltage between this plating pattern and the base metal was measured, a value of 400 to 600V was obtained.

Further, this sample was heated at 300°C for 30 minutes, but no change was observed in the oxide film, indicating that it had high heat resistance.

[Example 2] In the same manner as in Experimental Example 1, an aluminum plate having an anodized film with heat cracks was prepared.

This aluminum plate was heated at a current density of 0.05 A in a 3% oxalic acid aqueous solution.
/dm, and re-anodized for 10 minutes at a bath temperature of 20°C.

Titanium octylene glycolate (C4H90)2Ti(C8H1602) 50 v
Vacuum impregnation treatment was performed in a mixed solution of 1% methanol and 50 vol% methanol.

Next, the solution on the oxide film was thoroughly wiped off, and then heated and polymerized.

Next, a 1010×10 plating pattern was formed in the same manner as in Example 1, and when the AC dielectric strength voltage between the plating pattern and the base metal was measured, a withstand voltage of 600 μ was obtained.

This sample was heated at 300° C. for 30 minutes, but there was no change in the oxide film, indicating that it had excellent heat resistance.

[Example 3] As the polymerizable organometallic compound solution in Example 2, methylaluminum butoxide CH3Al(C4H2O)
270 vo1%, isopropanol 30■o1%,
When similar treatment was performed using a mixed solution of 600
A breakdown voltage of (2) was obtained, and no deterioration in the properties of the oxide film was observed even after a heating test at 300° C. for 30 minutes.

[Example 4] 10100X50X1 magnesium alloy plate (JIS1
seeds) with acidic ammonium fluoride 300g/l, sodium dichromate 100g/l, phosphoric acid (85%) 90Tl
In an aqueous solution containing l/l, bath temperature 75°C1 current density 5
Anodized for 50 minutes at A/d m” to a thickness of approx.
A 1 frrL anodic oxide film was formed.

This magnesium alloy plate was heated in a heating furnace at 350° C. for 30 minutes to generate cracks in the anodic oxide film.

Next, this oxide film was placed in the above aqueous solution at a bath temperature of 75°C and a current density of 0. Re-anodized at IA/dm' for 10 minutes.

This film was then treated with 85 v methyltriethoxysilane.
ow%, 5 vol% ethanol, and 10 vol% water using the above film as an anode, the film was subjected to a DC current treatment of 1 kV and 15 mA for 1 hour, and then heated at 150° C. for 2 hours.

When the AC dielectric strength voltage of this treated magnesium alloy plate was measured in the same manner as in Example 1, a value of 700 or more was obtained.

Furthermore, even when heated at 300° C. for 30 minutes, no cracks were observed in the oxide film.

[Example 5] In the same manner as in Example 1, five aluminum plates having anodic oxide films that were heated and cracked were prepared, and zirconium tetraisopropoxide and tri-n-butyl phosphate were applied to these plates. Ester, tri-n-butyl borate, methylgermanium trimethoxide, and dimethyloxyethyltin were vacuum impregnated into the fine pores of the film.

Next, these were left in the air for 24 hours to perform hydrolysis, and then heated at 130° C. for 2 hours to polymerize.

Next, a plating pattern was formed in the same manner as in Example 1, and the AC dielectric strength voltage between the plating pattern and the base material was measured, and was found to be 500 .ANG. or more in all cases.

In addition, these substrates were heated at 300°C for 30 minutes, but
No cracks were observed in the oxide film.

As explained above, the method for treating an anodic oxide film of the present invention involves heating the anodic oxide film formed on an anodizable metal to generate cracks, and then impregnating and polymerizing the anodic oxide film with a polymerizable organometallic compound. The anodic oxide film that has generated cracks is then anodized again, and then impregnated with a polymerizable organometallic compound and polymerized, so the micropores and cracks in the anodized film are removed by the highly thermally conductive organometallic compound polymer. Because it is embedded in the packaging, electrical insulation and corrosion resistance are greatly improved, and the high thermal conductivity of the oxide film is maintained.

Moreover, since cracks are generated once in the anodic oxide film, cracks will not be generated by subsequent heating, and the performance of the oxide film will not deteriorate.

Therefore, the anodized film treated according to the present invention can be used for printed wiring boards, insulating heat sinks, heat-resistant insulated wires, building materials, corrosion-resistant materials, and the like.

Claims (1)

[Claims] 1. An anodized film formed on an anodizable metal is heated to generate cracks, and then a general formula (wherein M: Si, Ti, Idl, Zr, X: vinyl group, Amine group, mercapto group, epoxy group,
An organic functional group R such as a methyl group or a phenyl group: a hydrolyzable organic group such as an alkoxy group or an acetoxy group or a halogen group (n+m=3.4.5 or 6) is used as an anode. A method for treating an anodized film, characterized by impregnating and polymerizing micropores and cracks in the oxide film. 2. After heating the anodic oxide film formed on the anodizable metal to generate cracks, and then anodizing the anodic oxide film again, the general formula (where M: Si, Ti1All, , Zr : Vinyl group, amine group, mercapto group, epoxy group,
An organic functional group R such as a methyl group or a phenyl group: a hydrolyzable organic group such as an alkoxy group or an acetoxy group or a halogen group (n+m=3.4.5 or 6) is used as an anode. A method for treating an anodized film, characterized by impregnating and polymerizing micropores and cracks in the oxide film.