JPS5834556B2 - How to treat anodized 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, heat resistance, and electrical insulation.

Anodized films of metals such as aluminum, titanium, tantalum, and their alloys are metal oxide films chemically formed on the surfaces of these metals, and have a uniform structure, good adhesion to the underlying metal, and high thermal conductivity. It is an insulating film.

Recently, using the characteristics of this anodic oxide film, metal plates with anodized oxide film can be used as printed wiring boards of electronic devices, ICs, etc.
It is being considered for use in heat sinks for LSIs.

When using anodic oxide films for these applications, the film is made thick to improve insulation, but anodic oxide films with a thickness of several micrometers or more inevitably have many micropores. Occur.

These micropores are several hundred amps in diameter, and even the barrier layer of the anodic oxide film is broken.

For this reason, with a thick anodic oxide film, a small amount of current flows due to moisture in the air and residual electrolyte during anodization, making it impossible to obtain sufficiently high insulation.

In order to improve this drawback, the micropores are sealed with steam or boiling water. However, when the pores are sealed, the oxide film deteriorates due to hydration, and the anodic oxide film changes even after being heated to around 150°C. There is a problem in that the electrical insulation properties deteriorate due to cracks.

Another method is to form a resin film on the surface of the anodized film to close the micropores, but although this method improves electrical insulation, it reduces thermal conductivity and causes problems such as problems with printed wiring boards and heat dissipation as mentioned above. It is unsuitable for use as a board.

In addition, if a wiring board with an anodic oxide film is heated by heat from electronic components or heated during soldering, the anodic oxide film, which is an insulating layer, will crack and the wiring conductor will break. There are also disadvantages in that the circuit may be broken due to cracks, and moisture in the air may enter through the cracks, reducing electrical insulation.

The cause of cracks in the anodic oxide film is the large difference in thermal expansion coefficient between the anodic oxide film and the base metal.

For example, the coefficient of thermal expansion of aluminum is approximately 25 x 10 =
On the other hand, the coefficient of thermal expansion of aluminum oxide, which is the main component of the anodic oxide film, is approximately 6×10=, which is significantly different, and cracks occur due to thermal stress when heated.

This invention was made in view of the above circumstances, and aims to provide a treatment method capable of forming an anodic oxide film having high thermal conductivity, heat resistance, and electrical insulation. After anodizing the metal plate while applying an external force that generates tensile stress in a direction parallel to the surface of the metal plate, a polymerizable organometallic compound is attached and deposited in the micropores and on the surface of the resulting anodic oxide film. , is characterized by polymerization.

The present invention will be explained in detail below.

The metal plate that can be anodized used in this invention is as follows:
Plate materials of so-called "valve metals" such as aluminum, titanium, Kunkle, and alloys of these metals are used.

These plates are first attached to, for example, a biaxial tensioning machine shown in FIG. 1 in order to generate tensile stress in a direction parallel to the surface of the plates.

The four sides of the plate material 1 are the chucks 2at2a of the biaxial tensioner 2,
2a, firmly gripped by 2a, biaxial tensioner 2
It is simultaneously pulled in two axial force directions by the oil ball cylinders 2b, 2b, 2b, 2b.

As a result, tensile stress is generated in the plate 1 in all directions parallel to its surface.

The tensile stress generated at this time is preferably less than the elastic deformation limit of the plate 1, preferably 1 of the yield point of the plate 1.
00% to 50% is good.

Further, when generating tensile stress in the plate material 1, it is necessary to prevent crimp stress from occurring in a direction parallel to the surface.

Next, the plate material 1 is anodized while maintaining the state in which tensile stress is generated in the plate material 1.

For example, as shown in FIG. 2, the cylinder 3 is placed on the plate material 1 where tensile stress is generated using putty, sealing material, etc. to prevent liquid leakage, and the inside of the cylinder 3 is This can be carried out by filling the plate with an electrolytic solution 4, using the plate 1 as an anode, and using a suitable conductor 5 as a cathode for electrolysis.

As the electrolytic solution 4, an alkaline bath or the like may be arbitrarily used as well as an acidic bath of an aqueous solution of sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, chromic acid, or the like.

As the electrolytic current, direct current, AC/DC superimposed current, etc. can be used.

Once an anodized film of the required thickness is obtained as described above, the electrolytic device on the plate 1 is removed, washed with water, and then the plate 1 is removed from the tensioner 2 to remove the tensile stress.

According to this method of forming an anodic oxide film, the base plate is anodized while being pulled by an external force, and after the anodization, the external force is removed, so the anodic oxide film is constantly subjected to shrinkage force. is in a state of being.

Even if the anodic oxide film, which is constantly subjected to shrinkage force, expands thermally when heated, it can alleviate the difference in thermal expansion with the base metal.

Therefore, the anodic oxide film formed in this manner has a high temperature variation in which heating cracks occur, and is less likely to generate heating cracks.

The metal plate on which the anodic oxide film has been formed in this manner is then 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, r-glycidoxypropyltrimethoxysilane, tetraisopropylbis(dioctylphosphite)titanate, tetraoctylbis(to ditridecylphosphite 1)titanate, titanium acetyl Organotitanium compounds such as acetonate, titanium octylene glycolate, dihydroxybis(lact)titanium, and tetrastearoxytitanium; organoaluminum compounds such as aluminum 1-n-butoxide, methylaluminum sesquichloride, and aluminum triisopropoxide; Organic metal compounds such as organic zirconium compounds such as zirconium tetra n-butoxide and zirconium tetraisopropoxide, derivatives of these compounds, and low polymers (oligomers) can be used, but those having an aromatic ring in the organic functional group However, it is preferable because the improvement in heat resistance is greater.

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.

As the water-soluble organic solvent, methanol, ethanol, isopropanol, acetone, dioxane, ethylene glycol, methyl acetate, methyl ethyl ketone, diacetone alcohol, ethyl formate, dimethylformamide, etc. are used, and if necessary, a catalyst, Additives such as surfactants can be added.

Then, the anodic oxide film is immersed in such a polymerizable organometallic compound solution to diffuse and permeate the polymerizable organometallic compound into the micropores, or the solution is applied to the oxide film surface. This is carried out by forming a polymerizable organometallic compound layer 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 of the micropores of the oxide film to the pore openings by electrophoresis, osmosis, etc.

When the resulting anodic oxide film requires higher thermal conductivity, the polymerizable organometallic compound solution adhering to the oxide film surface is completely wiped off, and when higher electrical insulation is required, the oxide film The polymerizable organometallic compound solution adhering to the surface is left as it is without being wiped off.

Once the polymerizable organometallic compound has been sufficiently attached and deposited on the surface or micropores of the anodic oxide film, the oxide film is dried and excess water and organic solvent are removed.

The polymerizable organometallic compound attached to or deposited on the surface of the anodic oxide film or in the micropores as described above is polymerized by a polymerization means such as heating.

Through this polymerization, the polymerizable organometallic compound becomes a dense organometallic compound polymer, and since these organometallic compounds have a high affinity with the oxide film, the surface of the oxide film,
It firmly adheres to the inside of the pore, filling the inside of the fine pore tightly or covering the surface.

The anodic oxide film treated with a polymerizable organometallic compound has extremely high electrical insulation properties because the micropores are completely filled with the organometallic compound polymer, or the film surface is also coated with the polymer. is obtained.

Furthermore, since only the micropores can be filled with the polymer, electrical insulation is improved while maintaining high thermal conductivity.

Furthermore, electrical insulation properties at high temperatures (approximately 150° C.) are also improved.

Furthermore, since the filled and coated polymer is metallic, the polymer itself has excellent thermal conductivity, and the anodic oxide film whose surface is coated with this polymer also has high thermal conductivity.

The present invention will be specifically described below based on experimental examples and examples.

Experimental Example 1 The four sides of a 2SAD plate O material measuring 150 mm x 150 mm x 1 mm were gripped by a steel chuck with a width of 130 mm, and an external tensile force of 2 kg/- was applied in each of the vertical and horizontal directions.

While maintaining this state, a rubber frame of 80 mm diameter is pressed against the center of the Al plate, a 15% sulfuric acid aqueous solution is poured into the rubber frame as an electrolyte, and lead is used as the cathode, and the bath temperature is 15℃ 0.
, anodic oxidation was performed at a current density of 1i2 A/dm to form an anodic oxide film with a thickness of 30 μm.

As a comparative example, the same A7 plate was anodized under the same conditions without applying any external tensile force.

These samples were heated at 20° C. intervals and heated for 30 minutes at each temperature to examine the crack generation temperature.

As a result, the crack initiation temperature of the sample anodized with an external tensile force applied was 2'60°C, and that of the sample anodized without the external tensile force (comparative example) was 160°C.
A crack occurred.

In addition, the tensile external force during anodization is Ikg/mt 3k
The sample with y/ma also did not develop cracks up to the same temperature <260°C.

Example 1 An anodized film was formed by anodizing in a 15% oxalic acid aqueous solution at a bath temperature of 30° C. while applying a tensile external force in the same manner as in Experiment 1.

This anodized film was used as an anode, and electricity was applied for 30 minutes at a constant 500 V DC in a mixed solution of methyltriethoxysilane CH3Sl(OC2H5) 3SO%, ethanol 40%, and water 10% to anodize the polymerizable organometallic compound. After thoroughly wiping off the solution impregnated into the film and adhering to the surface of the sample, it was dried with hot air and heated at 130°C for 2 hours to polymerize.

When a mercury droplet with a diameter of 5 m7IL was placed on the obtained anodic oxide film and the insulation resistance between it and the base aluminum plate was measured, a value of 600 V or more was obtained.

This sample was heated at 300° C. for 30 minutes, but no cracks were observed in the film and there was no deterioration in insulation properties.

Further, this sample was left indoors for one week and the insulation resistance was then measured, but no decrease in electrical insulation due to the influence of humidity or cold was observed.

Example 2 In the same manner as in Example 1, an anodized film was formed by anodizing with an external tensile force applied.

This anodic oxide film is used as an anode, and dihydroxy bis(
Lactato) Titanium T 1(OH)2(OCH(CHs)
COOH] 250% DC 20 mA/in aqueous solution
The polymerizable organometallic compound was impregnated into the micropores by applying reverse current for 30 minutes at a constant value of d m.

Thereafter, the treatment was carried out in the same manner as in Example 1, and the insulation property of the film was measured, and a property of 600V was obtained.

Furthermore, no cracks occurred in the film even after heating at 300° C. for 30 minutes.

Example 3 An anodized film subjected to anodization treatment with an external tensile force applied in the same manner as in Example 1 was placed in a desicake 10-3.
After reducing production to torr, tributoxyaluminum Al
It was vacuum impregnated by immersing it in a solution of (OC4H2) 360% and acetone 40%.

After wiping off the liquid adhering to the surface of the alumite plate, it was left in the air for 24 hours and then heated and polymerized.

When the insulation resistance of the film was measured in the same manner as in Example 1, a resistance of 600V was obtained.

Further, even when this sample was heated at 300° C. for 30 minutes, no cracks were observed in the anodic oxide film.

Example 4 An anodized film subjected to anodization treatment with an external tensile force applied in the same manner as in Example 1 was placed in a desiccator at 10” to
After reducing the volume to rr, it was immersed in a solution of 60% zirconium tonoisopropoxide and 40% acetone for vacuum impregnation.

After wiping off the liquid adhering to the surface of the alumite plate, it was left in the air for 24 hours and then heated and polymerized.

The insulation property of the film was measured in the same manner as in Example 1, and a resistance of 600V was obtained.

Further, even when this sample was heated at 300'C for 30 minutes, no cracks were observed in the anodic oxide film.

As explained above, the method for treating an anodized film of the present invention involves performing anodization on a metal plate that can be anodized while applying an external force that generates a tensile stress in a direction parallel to the surface of the metal plate.
Since the polymerizable organometallic compound is attached, deposited, and polymerized in the micropores and surface of the obtained anodic oxide film, the anodized film has a high heating crack generation temperature, making it difficult for heating cracks to occur. , the insulation properties of the anodic oxide film at high temperatures are greatly improved.

Furthermore, since the micropores of the anodic oxide film are filled with an organometallic compound polymer, high electrical insulation is obtained, and the high thermal conductivity inherent to the anodic oxide film is maintained.

Therefore, the anodic oxide film treated by the treatment method of this invention can be used on printed wiring boards, insulating heat sinks, ICs, L
Used for mounting boards such as SI.

[Brief explanation of drawings]

The drawings show an example of an apparatus suitable for carrying out the method of treating an anodic oxide film according to the present invention. 1 is a schematic configuration diagram of an apparatus that performs anodic oxidation in a state where tensile stress is generated. 1...Metal plate material, 2...Tensioner, 3.
... Cylinder, 4 ... Electrolyte, 5 ...
·cathode.

Claims (1)

[Claims] 1. Anodizing a metal plate that can be anodized while applying an external force that generates tensile stress in a direction parallel to its surface, and forming a general Formula XnMRm (wherein M: S i , Ti , Al, Zr X: vinyl group, amino group, mercapto group, epoxy group,
Organic functional groups such as methyl groups and phenyl groups R: Hydrolyzable organic groups such as alkoxy groups and acetoxy groups, and halogen groups (n + m = 3 + 4 + 5 or 6); A method for treating an anodic oxide film, which is characterized by impregnating and adhering all the metals, and then polymerizing them.