JP2008041838A - Metal core board and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal core board wherein the peeling and/or the discoloration due to heat is less likely to occur and a thick-film circuit can be formed, and to provide a manufacturing method therefor. <P>SOLUTION: This manufacturing method of the metal core board comprises an anodic oxidation step for forming an anodic oxide film 2 on a metal plate 1, a polymerization forming step for forming a metal alkoxide polymerization layer 3 on the anodic oxide film 2, and a metal layer forming step for forming a metal layer 4 on the metal alkoxide polymerization layer 3. Since the anodic oxide film 2 and/or the metal alkoxide polymerization layer 3 excel in thermal resistance, decomposed gas will not generate so that the peeling and/or the discoloration is less likely to occur. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a metal core substrate and a metal core substrate that are excellent in thermal conductivity and heat resistance and are less likely to cause discoloration due to decomposition of an insulating layer.

  With the integration of electronic circuits, wiring substrates on which electronic components are mounted are required to have excellent heat dissipation characteristics. For this reason, metal core substrates based on metals such as aluminum having excellent thermal conductivity have been developed in place of conventional glass epoxy wiring substrates. For example, Patent Document 1 describes a metal core substrate in which a resin film with a copper foil is attached to a metal core, or a metal core is attached directly to a copper foil via a prepreg.

  However, in the metal core substrate in which the metal core is bonded to the metal core with such a resin interposed, there is a problem that the resin decomposes and peels off due to heat generated from the electronic component, or the discolored product causes discoloration. It was happening. In particular, in the mounting of light emitting diodes, discoloration and peeling have been problems due to an increase in the amount of heat generated by integration and high brightness. In addition, since a resin having inferior thermal conductivity is used as the insulating layer, it cannot be said that the insulating layer has sufficient heat dissipation characteristics.

For this reason, a metal core substrate in which an anodized film is formed on a metal core such as an aluminum plate and this is used as an insulating layer, and further printed with an ink for forming a conductive film containing a glass component on the anodized film and baked. A manufacturing method has also been proposed (Patent Document 2). Since the metal core substrate obtained by this method does not use a resin for the insulating layer, it has excellent heat resistance and is less likely to be discolored by decomposition products. It also has excellent heat dissipation characteristics.
JP, 2006-100316, A Paragraph number 0013 JP, 2005-175427, A Paragraph Nos. 0018-0019

  However, in the metal core substrate described in Patent Document 2, in order to bake the ink, it must be heated until the glass component contained in the ink is melted, which may reduce the electrical insulation of the anodized film. (See paragraph number 0019 of Patent Document 2 above). For this reason, it has also been proposed to form a circuit by sputtering or vapor deposition, but this requires a large-scale device and the circuit thickness becomes extremely thin, so that the allowable current is reduced. There was also a problem.

  The present invention has been made in view of the above-described conventional situation, and it is an object to be solved to provide a metal core substrate and a method for manufacturing the metal core substrate that are less likely to be peeled off or discolored by heat and can form a thick film circuit. .

  The method for producing a metal core substrate according to the first aspect of the present invention includes an anodizing step for forming an anodized film on a metal plate, a polymerized layer forming step for forming a metal alkoxide polymerized layer on the anodized film, and a metal alkoxide. And a metal layer forming step of forming a metal layer on the polymerized layer.

  In this method of manufacturing a metal core substrate, first, as an anodizing step, a metal plate such as aluminum or an aluminum alloy is anodized to form an anodized film as an insulating layer on the metal plate. Next, as a polymerization layer forming step, a metal alkoxide polymerization layer is formed on the anodized film. As a method for forming the metal alkoxide polymerization layer, a metal alkoxide solution such as silicon alkoxide or a hydrolyzate thereof may be attached to the anodized film by a method such as coating, spraying or spin coating, and dried. And as a metal layer formation process, a metal layer is formed on a metal alkoxide polymerization layer. Examples of the method for forming the metal layer include a method in which a metal foil such as copper is pressure-bonded using a metal alkoxide polymerization layer as an adhesive, a method by vapor deposition or sputtering, and the like.

  The metal core substrate manufactured in this way is excellent in heat dissipation characteristics because an anodized film or a metal alkoxide polymerized layer having better thermal conductivity than the resin is used as the insulating layer. In addition, since no resin such as epoxy is used, it has excellent heat resistance and does not generate decomposition gas that causes discoloration. Furthermore, if a metal foil is crimped as a method for forming the metal layer, a thick film circuit can be formed.

In the method for manufacturing a metal core substrate according to the second aspect of the present invention, the anodized film is not sealed. Since the anodic oxide film not subjected to the sealing treatment has fine pores, the metal alkoxide polymer is filled into the fine pores in the polymerization layer forming step. For this reason, the anodized film becomes denser, the thermal conductivity is further improved, and the mechanical strength is also increased.
It is of course possible to form a metal alkoxide polymerization layer on the anodized film that has been subjected to the sealing treatment. Since the anodic oxide film densified by the sealing treatment exhibits excellent corrosion resistance, the metal core substrate on which the metal alkoxide polymer layer is formed also exhibits excellent corrosion resistance.

  In the method for manufacturing a metal core substrate according to the third aspect of the present invention, the formation of the metal layer in the metal layer forming step is performed by pressure-bonding a metal foil to the semi-cured metal alkoxide polymerization layer. The semi-cured metal alkoxide polymerized layer has viscosity and functions as an adhesive, so that the metal foil can be securely crimped.

  In the metal core substrate manufacturing method according to the fourth aspect of the present invention, the metal alkoxide is silicon alkoxide. Silicon alkoxide easily causes a sol-gel reaction to form a dense metal alkoxide polymerized layer. Moreover, since it is cheaper than other metal alkoxides, the manufacturing cost can be reduced.

  In the metal core substrate manufacturing method of the fifth aspect of the present invention, a through hole is formed in the metal plate, and the anodizing step, the polymerization layer forming step, and the metal layer forming step are performed around the through hole. It was decided to be executed on the surface. In this manner, a double-sided circuit board with through holes in which electrical conduction is made between the front and back sides can be obtained.

  The metal core substrate of the present invention is manufactured by the method for manufacturing a metal core substrate of the first aspect of the present invention. That is, the metal core substrate of the present invention comprises a metal plate on which an anodized film is formed, a metal alkoxide polymer layer formed on the anodized film, and a metal layer formed on the metal alkoxide polymer layer. It is characterized by becoming.

As the metal used in the anodizing step, any metal can be used as long as it can form an anodized film capable of obtaining electrical insulation. Examples of such metals include aluminum, various aluminum alloys, and magnesium alloys.
Also, in the anodizing step, an anodized film may be formed on the entire surface of the metal plate. However, a patterned anodized film is obtained by anodizing a previously masked metal plate and removing the masking. You can also. In this way, the portion where the metallic luster portion is left can also be used for a reflection plate or the like when mounting an LED, for example.

The metal alkoxide used in the polymerization layer forming step is not particularly limited as long as it condenses between molecules by a sol-gel reaction in the presence of water. For example, the general formula is R _m Si (OR) _4-m (here Wherein R represents a hydrocarbon group such as an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, and m represents an integer of 0 to 3, and the general formula is R _m Al (OR ) _3-m (wherein R represents a hydrocarbon group such as an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, and m represents an integer of 0 to 2), various aluminum alkoxides represented by the general formula various but represented by _{R m Ti (OR) 4-} m ( wherein R represents an alkyl group, an alkenyl group, a phenyl group, a hydrocarbon group such as a cycloalkyl group, m represents an integer of 0 to 3) of Titanium alkoxide, R _m Zr (OR) _4-m (wherein R represents a hydrocarbon group such as an alkyl group, an alkenyl group, a phenyl group, a cycloalkyl group, and m represents an integer of 0 to 3). Various zirconium alkoxides can be used. Further, these metal alkoxides can be used in combination.

  Examples of the method for forming the metal layer in the metal layer forming step include a method in which a metal alkoxide polymerization layer is used as an adhesive and a metal foil such as copper is pressure-bonded, a method by vapor deposition or sputtering, and the like.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments that further embody the present invention will be described with reference to the drawings.
(Embodiment 1)
In Embodiment 1, a metal core substrate was produced by the process shown in FIG.
<Anodizing process>
The aluminum plate 1 was cut into a predetermined size and anodized in a normal anodized bath such as a sulfuric acid bath or an oxalic acid bath to form an anodized film 2. However, the sealing treatment was not performed.

<Polymerization layer formation process>
Next, 9.1 g of water and 1.5 g of acetic acid were added to 50 g of phenyltrimethoxysilane as a metal alkoxide, and the mixture was stirred at room temperature for 24 hours. Then, it diluted with alcohol (isopropyl alcohol, n-propanol, ethanol etc.), and obtained the solution of the desired density | concentration. Using this solution, the aluminum plate on which the anodized film is formed is dipped and pulled up, and then semi-cured at 50 to 80 ° C. In this way, a semi-cured silicon alkoxide polymerization layer 3 is formed on the anodized film. Since the anodic oxide film 2 is not sealed, the silicon alkoxide penetrates into the fine holes formed in the anodic oxide film 2 and is filled with the polymer.

<Metal layer formation process>
With the silicon alkoxide polymerization layer 3 semi-cured in this way, a copper foil 4 with a film thickness of 30 μm is placed thereon and pressure bonded by a roll press. And it hold | maintained at 200 degreeC for about 30 minutes, the silicon alkoxide was fully polymerized, and the metal core board | substrate was obtained.

  The metal core substrate obtained as described above is composed of an anodic oxide film and a polymerized layer of silicon ethoxide, which are better in thermal conductivity and heat resistance than resin as an insulating layer. There is no generation of cracked gas that causes Furthermore, the fine pores of the anodized film that has not been sealed are filled with a polymer of silicon ethoxide, so that the anodized film becomes dense, further improving thermal conductivity, and mechanical strength. Will also increase. Further, since the circuit is formed by a thick film of copper foil of 30 μm, the allowable current is also increased.

(Embodiment 2)
The second embodiment is a method for manufacturing a metal core substrate using a sputtering technique in the metal forming step, and was manufactured as follows.
<Anodizing process>
The anodizing step is the same as that in the first embodiment, and a description thereof is omitted.

<Polymerization layer formation process>
Next, 8.6 g of water and 14.4 g of acetic acid are added to 50 g of tetraethoxysilane as a metal alkoxide, and the solution diluted with n-propanol is stirred at 60 to 80 ° C. for 2 hours and adjusted to a desired concentration with n-propanol. Further dilution was performed. Using this solution, the aluminum plate on which the anodized film is formed is dipped, pulled up, held at 200 ° C. for 10 minutes, and completely polymerized.

<Metal layer formation process>
After the silicon alkoxide polymerized layer was completely cured in this manner, it was placed in a chamber of a sputtering apparatus and Cu sputtering was performed to form a copper film on the silicon alkoxide polymerized layer to obtain a metal core substrate.
In place of sputtering, electroless copper plating can be applied.

  In the metal core substrate of the second embodiment, the insulating layer is composed of an anodized film and a polymerized layer of silicon ethoxide, so that it has excellent heat dissipation characteristics and heat resistance and does not generate decomposition gas that causes discoloration. Furthermore, since the polymer of silicon ethoxide is filled in the fine pores of the anodized film that has not been sealed, the anodized film becomes dense, further improving thermal conductivity, and mechanical strength. Increase.

  As a modification of the second embodiment, the metal is patterned with a masking agent before the anodizing step to form a pattern of the anodized film, and further, a fully additive patterned circuit is formed in the metal layer forming step. May be. FIG. 2 shows an example in which LEDs are mounted using the metal core substrate thus obtained. The LED 5 is mounted on a portion where the aluminum plate 6 is exposed, and an anodized film 7 and a copper plating layer 8 are formed around the LED 5. For this reason, the light emitted from LED5 will be reflected by the aluminum plate 6, and a reflectance can be improved significantly. This is particularly suitable when an aluminum plate having a high reflectance is used.

(Embodiment 3)
In Embodiment 3, a metal core substrate on which a double-sided circuit in which electrical continuity was made between the front and back sides was formed was manufactured as follows (see FIG. 3).

<Drilling process>
The aluminum plate 11 is cut into a predetermined size, and a through hole 11a is opened at a predetermined position.

<Anodizing process>
The aluminum plate 11 having the through holes 11a was anodized in an alumite bath to form an anodized film 12. Thereby, the peripheral surface of the through-hole 11a is also anodized. However, the sealing treatment was not performed.

<Polymerization layer formation process>
Next, 8.6 g of water and 14.4 g of acetic acid are added to 50 g of tetraethoxysilane as a metal alkoxide, and the solution diluted with n-propanol is stirred at 60 to 80 ° C. for 2 hours and adjusted to a desired concentration with n-propanol. Further dilution was performed. Using this solution, the aluminum plate on which the anodic oxide film 12 was formed was dipped, pulled up, held at 200 ° C. for 10 minutes, and completely polymerized. Thereby, the metal alkoxide polymerization layer 13 is also formed on the anodic oxide film 12 of the through hole 11a.

<Metal layer formation process>
After the silicon alkoxide polymerization layer 13 was completely cured in this way, a copper plating layer 14 was formed on the surface of the substrate and the peripheral surface of the through hole 11a by electroless copper plating to obtain a metal core substrate.
Instead of electroless copper plating, a via hole in which the conductive paste is filled in the through hole 11a may be used.

  Since the copper plating layer 14 is formed up to the side wall of the through-hole 11a by electroless copper plating, the metal core substrate thus obtained becomes a double-sided circuit board with through holes in which electrical conduction is made between the front and back surfaces.

  The present invention is not limited to the embodiments of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.

FIG. 3 is a process diagram in the first embodiment. It is sectional drawing at the time of mounting LED on the metal core board | substrate of the modification of Embodiment 2. FIG. FIG. 10 is a process diagram in the third embodiment.

Explanation of symbols

1, 11 ... Metal plate (aluminum plate)
2, 12 ... anodized film 3, 13 ... metal alkoxide polymerization layer (silicon alkoxide polymerization layer)
4, 14 ... Metal layer (4 ... Copper foil, 14 ... Copper plating layer)

Claims (6)

An anodizing step of forming an anodized film on the metal plate;
A polymerized layer forming step of forming a metal alkoxide polymerized layer on the anodized film;
A metal layer forming step of forming a metal layer on the metal alkoxide polymerization layer;
A method of manufacturing a metal core substrate, comprising:   2. The method of manufacturing a metal core substrate according to claim 1, wherein the anodized film is not sealed.   3. The method of manufacturing a metal core substrate according to claim 1, wherein the metal layer is formed in the metal layer forming step by pressing a metal foil onto the semi-cured metal alkoxide polymerization layer.   4. The method for manufacturing a metal core substrate according to claim 1, wherein the metal alkoxide is silicon alkoxide.   The through hole is formed in the metal plate, and the anodizing step, the polymerization layer forming step, and the metal layer forming step are performed also on a peripheral surface of the through hole. Item 5. A method for producing a metal core substrate according to any one of Items 1 to 4.   A metal core substrate comprising: a metal plate having an anodized film formed thereon; a metal alkoxide polymer layer formed on the anodized film; and a metal pattern layer formed on the metal alkoxide polymer layer. .

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