JP2005277137A - High efficiency heat conducting circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high efficiency heat conducting circuit board and to provide a method of manufacturing the same. <P>SOLUTION: The high efficiency heat conducting circuit board for electrically connecting an electronic part (5) includes a plurality of conductive contactors (4) for electrically connecting a metal oxide layer (3) formed of a micro arc oxidation on a metal substrate (2) and the electronic part (5) formed by plasma ion plating on the metal oxide layer (3). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-efficiency heat conduction circuit board and a manufacturing method thereof, and more specifically, a metal substrate on which a metal oxide layer is formed and a conductive material electrically connected to an electronic component formed on the metal oxide layer. The present invention relates to a high-efficiency heat conduction circuit board having a conductive contact and a manufacturing method thereof.

  In the past, the heat dissipation and electrical insulation requirements of electrical and photoelectric components could be satisfied by the use of resin substrates because the heat generated as a result of the operation of those components was not very high. In recent years, due to the widespread use of information and communication products, the demand for electronic devices such as dynamic random access memory (DRAM) in the market is increasing, and the manufacturing process of semiconductors and photoelectric components is very large scale integrated circuits ( VLSI). The problem of heat dissipation in multi-layered devices is serious and cannot be ignored.

  As shown in FIG. 1, a conventional circuit board 1 used for an electronic device includes an aluminum substrate 11, an epoxy resin layer 12 formed on the aluminum substrate 11, and an electrochemical plating on the epoxy resin layer 12. Copper contacts 13.

  Since the difference in surface characteristics between the epoxy resin layer 12 and the copper contact 13 is large, the copper contact 13 can hardly adhere to the epoxy resin 12. Therefore, prior to electrochemical plating of the copper contactor 13 on the epoxy resin layer 12, the surface of the epoxy resin layer 12 is roughened and the surface of the epoxy resin layer 12 is sensitized and activated by oxidation-reduction reaction. A series of pretreatments like this must be performed to improve the adhesion of the copper contact 13 to the epoxy resin layer 12.

The conventional circuit board 1 has the following drawbacks.
(1) The epoxy resin layer 12 has a low thermal conductivity of 0.2 W / m / K, which cannot meet the current heat dissipation requirements of the integrated circuit industry, and so on. Due to the low thermal conductivity, the service life of the components attached to the substrate 11 can be shortened.
(2) The surface of the epoxy resin layer 12 needs to be pretreated prior to the electrochemical plating of the copper contactor 13, and such pretreatment is complicated and expensive.
(3) Since it is necessary to pre-process the epoxy resin layer 12 by roughening the surface, it is not possible to achieve a thin line width of the integrated circuit.
(4) Forming the copper contact 13 by electrochemical plating is a source of water pollution.

  Therefore, an object of the present invention is to provide a high-efficiency heat conduction circuit board and a method for manufacturing the same in order to overcome the above-mentioned drawbacks of the prior art.

  According to one aspect of the present invention, a high-efficiency heat conduction circuit board that electrically connects electronic components is provided. The conductive circuit board includes a metal substrate, a metal oxide layer formed on the metal substrate, and a plurality of conductive contacts electrically connected to electronic components formed on the metal oxide layer. including.

  According to another aspect of the present invention, a method for manufacturing a high-efficiency heat conduction circuit board that electrically connects electronic components is provided. The method includes: (a) placing a metal substrate in an electrolytic cell; and (b) oxidizing the metal substrate in the electrolytic cell and forming a metal oxide layer thereon by microarc oxidation. And (c) forming a plurality of conductive contacts on the metal oxide layer for electrically connecting electronic components.

  Other features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the invention, with reference to the accompanying drawings.

  Referring to FIG. 2, a preferred embodiment of the high efficiency heat conduction circuit board of the present invention is shown, which has two conductive leads 51 extending outwardly, such as light emitting diodes. The electronic component 5 is connected to electrically connect the metal substrate 2, the metal oxide layer 3 formed on the metal substrate 2, and the conductive leads 51 of the light emitting diode 5 formed on the metal oxide layer 3. A plurality of conductive contacts 4 connected to each other.

  In the present embodiment, suitable metals for manufacturing the metal substrate 2 include, but are not limited to, aluminum, titanium, magnesium, zirconium, beryllium, tantalum and alloys thereof. Preferably, the metal substrate 2 is made of aluminum.

  The metal oxide layer 3 is formed on the metal substrate 2 by micro arc oxidation, and is made of a metal oxide selected from the group consisting of alumina, titania, magnesia, zirconia, beryllia, tantalum oxide, and alloys thereof. Preferably, the metal oxide layer 3 formed on the metal substrate 2 is made of alumina.

  Suitable metals for forming the conductive contacts 4 on the metal oxide layer 3 include, but are not limited to, copper, silver, zinc, titanium and tungsten. Preferably, the conductive contact 4 is made of copper.

  Still referring to FIG. 3, a method for manufacturing a high-efficiency heat conduction circuit board electrically connected to an electronic component 5 according to the present invention includes: (a) placing a metal substrate 2 in an electrolytic cell; and (b) A step of oxidizing the metal substrate 2 in the electrolytic cell and forming a metal oxide layer 3 thereon by micro-arc oxidation; and (c) electrically connecting the electronic component 5 on the metal oxide layer 3. Forming a plurality of conductive contacts 4.

  Preferably, the electronic component 5 is a high-power electronic component such as a light emitting diode.

  In the present embodiment, the conductive contact 4 may be formed on the metal oxide layer 3 by performing physical vapor deposition after covering the metal oxide layer 3 with a patterned mask. As an alternative, the conductive contact 4 comprises the following steps: (i) forming a patterned photoresist layer on the metal oxide layer 3 using photolithography; Forming a conductive contact 4 corresponding to the pattern of the photoresist layer formed thereon by vacuum deposition; and (iii) a metal oxide such that the conductive contact 4 remains on the metal oxide layer 3. It may be formed by removing the patterned photoresist layer from layer 3.

  Preferably, metal substrate 2 is made of a metal selected from the group consisting of aluminum, titanium, magnesium, zirconium, beryllium, tantalum and alloys thereof. More preferably, the metal substrate 2 is made of aluminum.

  In step (b), a metal substrate 2 such as an aluminum substrate is placed in an electrolytic cell having an electrolyte composition, followed by a predetermined metal oxide layer 3 to form a metal oxide layer 3 on the metal substrate 2. Oxidized by micro-arc oxidation at a predetermined temperature for a time. Preferably, the electrolytic cell contains an aqueous ammonia solution. More preferably, the aqueous ammonia solution contains a water-soluble salt and a conductive assistant.

  The water-soluble salts contained in the aqueous ammonia solution include, but are not limited to, phosphates, chromates, silicates, carbonates and mixtures thereof. Preferably, the water soluble salt comprises a mixture of phosphate and chromate. More preferably, the water soluble salt comprises potassium dihydrogen phosphate and potassium chromate.

  The conductive assistant contained in the aqueous ammonia solution is a compound that can be ionized into acetate. Preferably, the conductive aid is copper acetate. In a more preferred embodiment, the electrolytic cell of step (b) of the above method comprises 0.3 to 0.6 mol / liter (M) of potassium dihydrogen phosphate and a concentration of 0.08 to 0.3 mol / liter. It consists of 2 to 6 volume percent aqueous ammonia solution of liter (M) potassium chromate and acetate ions at a concentration of 0.08 to 0.5 mol / liter (M).

  The microarc oxidation of the metal substrate 2 in the step (b) is performed in a temperature range of 0 ° C. to 150 ° C., preferably 0 ° C. to 40 ° C. The oxidation time ranges from 20 minutes to 150 minutes, preferably from 20 minutes to 100 minutes.

  In the present embodiment, physical vapor deposition for forming the conductive contact 4 includes, but is not limited to, cathodic arc plasma ion plating, sputtering, electron beam vapor deposition, and thermal vapor deposition. Preferably, the conductive contact 4 is formed by cathodic arc plasma ion plating. Cathodic arc plasma ion plating includes the steps of placing a metal substrate 2 on which a metal oxide layer 3 is formed on a base placed in a reaction chamber having a gas source and a metal target cathode, and metal atoms and ions. Applying a predetermined voltage to the metal target cathode by supplying power under a predetermined pressure to generate a predetermined current including an arc discharge to be formed; and a predetermined time for forming the conductive contact 4 And depositing metal atoms and ions on the metal oxide layer 3 on the metal substrate 2.

More preferably, the metal target cathode is made of a metal selected from the group consisting of copper, silver, zinc, titanium and tungsten. Most preferably, the metallic target cathode is made of copper. Gas sources suitable for cathodic arc plasma ion plating in this embodiment include, but are not limited to, Ar, N ₂ , H ₂ and mixtures thereof. Preferably, the predetermined pressure is in the range of 0.1 to 100 Pa, the predetermined voltage is in the range of 20V to 30V, the predetermined current is in the range of 10A to 150A, and the preferred time is 10 minutes to 300 minutes. Range.

A high-efficiency heat conduction circuit board is first composed of 0.5 mol / liter (M) potassium dihydrogen phosphate, 0.1 mol / liter potassium chromate, and a concentration of 0.35 mol / liter (M). The aluminum substrate 2 was arranged and prepared in an electrolytic cell made of a 4.5 volume percent aqueous ammonia solution with copper acetate. The surface of the aluminum substrate 2 is subjected to a temperature range of 0 ° C. to 40 ° C. and a current density of 0.045 A / cm ² for 30 minutes so that the alumina layer 3 has a thickness of approximately 15 μm on the aluminum substrate 2. Oxidized by micro arc oxidation.

  After the alumina layer 3 was formed on the aluminum substrate 2, a plurality of conductive contacts 4 were formed on the alumina layer 3 by cathodic arc plasma ion plating. First, the aluminum substrate 2 on which the alumina layer 3 was formed was placed on a base installed in the reaction chamber. A mask patterned by laser etching was placed on the alumina layer 3 of the aluminum substrate 2. Hydrogen gas was used as a gas source, and a voltage of 25 V was applied from a power source to a copper target cathode under an operating pressure of 4 Pa to pass a current of 90 A. During plating, arc discharge was generated on the surface of the copper target cathode so as to generate copper atoms and ions. A bias pulse (−50 V (40%) + 78 V (60%)) was applied for 100 minutes based on a mask of copper atoms and copper ions and to allow deposition on the alumina layer 3. When the mask was removed, a pattern of copper contacts 4 was formed on the alumina layer 3.

  Compared with conventional anodizing, the arc oxidation rate of ionized aluminum ions in the electrolytic cell is fast, and the alumina layer 3 has high purity, high compactness and low porosity. For this reason, the problem of a short circuit caused by filling the holes of the alumina layer 3 with copper during the formation of the copper contact 4 can be avoided.

  Furthermore, the cathode arc plasma ion plating technique can generate a high current by applying a low voltage to the target cathode, resulting in an arc discharge on the surface of the target cathode, and copper quickly ionizing from the surface of the copper target. As a result, the growth rate of the conductive contact 4 using cathodic arc plasma ion plating is high, and the density of the conductive contact 4 is increased.

  FIG. 4 shows a comparison of the heat dissipation effect between the above-described conventional circuit board shown in FIG. 1 and the high-efficiency heat conduction circuit board obtained in the first embodiment. The experiment was carried out by passing an operating current of 0.75 A for 3 hours through the conventional circuit board 1 to which the light emitting diode was connected and the high efficiency heat conduction circuit board of the present invention to which the light emitting diode was connected. Since the alumina layer 3 formed on the aluminum layer 2 has a thermal conductivity of 35 W / m / K, the heat generated by the light emitting diode can be quickly dissipated through the alumina layer 3 and the aluminum layer 2. Therefore, the light-emitting diode connected to the high-efficiency heat conduction circuit board of the present invention has a heat dissipation effect superior to that connected to the conventional circuit board 1.

  A high-efficiency heat conduction circuit board was prepared in the same manner as in Example 1 except for the formation of copper contacts. In this example, a patterned photoresist layer was formed on the alumina layer 3 by photolithography, and a copper film was formed on the alumina layer 3 under the same operating conditions as in Example 1. Finally, the photoresist layer was removed to form a copper contact 4.

The high-efficiency heat conduction circuit board according to the present invention has the following specific functions and features.
(1) The thickness of the metal oxide layer 3 is sufficient to provide electrical insulation.
(2) The purity and density of the metal oxide layer 3 are sufficient to effectively avoid the short circuit problem during the formation of the conductive contact 4.
(3) The thermal conductivity of the metal oxide layer 3 is relatively high, and heat generated by an electronic component such as a light emitting diode installed on the metal substrate 2 can be effectively dissipated.
(4) Adhesion of the conductive contact 4 to the metal oxide layer 3 is relatively strong and provides excellent thermomechanical properties that can withstand the stress applied to the electronic component due to the heat generated therein.
(5) The conductive contact 4 has a high density and low resistivity and reduces the generation of Joule heat.
(6) According to the above (3) to (5), the electronic component connected to the metal substrate 2 of the present invention has a long service life.
(7) The problem of water contamination in the conventional copper plating technique can be avoided by using the cathodic arc plasma ion plating technique.
(8) The conductive contact 4 having a narrow line width can be achieved by using a photolithography technique.
(9) The formation rate of the metal oxide layer 3 by micro arc oxidation and the conductive contact 4 by cathodic arc plasma ion plating is high. Therefore, the production time for manufacturing the high efficiency heat conduction circuit board is reduced.

  Although the invention has been described in connection with the most practical and preferred embodiments, the invention is not limited to the disclosed embodiments and is encompassed by the spirit and scope of the broad interpretation and equivalent arrangement. It is understood that it covers a variety of arrangements.

Sectional drawing of the conventional circuit board used for an electronic device. 1 is a cross-sectional view of a preferred embodiment of a high efficiency heat conduction circuit board connecting light emitting diodes according to the present invention. The flowchart which shows the continuous process of preferable embodiment of the manufacturing method of the highly efficient heat conductive circuit board by this invention. FIG. 5 is a polygonal diagram comparing the heat dissipation effect between a conventional circuit board and the high efficiency heat conduction circuit board of the present invention.

Explanation of symbols

2 Metal substrate 3 Metal oxide layer 4 Conductive metal contact 5 Electronic component

Claims (16)

A highly efficient heat conduction circuit board for electrically connecting electronic components (5),
A metal substrate (2);
A metal oxide layer (3) formed on the metal substrate (2);
A high-efficiency heat conduction circuit board comprising a plurality of conductive contacts (4) formed on the metal oxide layer (3) and electrically connecting the electronic component (5).   The high efficiency heat conduction circuit substrate according to claim 1, wherein the metal substrate (2) is made of a metal selected from the group consisting of aluminum, titanium, magnesium, zirconium, beryllium, tantalum and alloys thereof. .   The metal oxide layer (3) is made of a metal oxide selected from the group consisting of alumina, titania, magnesia, zirconia, beryllia, tantalum oxide and alloys thereof. High efficiency heat conduction circuit board. The metal substrate (2) is made of aluminum,
The high-efficiency heat conduction circuit board according to claim 3, wherein the metal oxide layer (3) is made of alumina.   The high-efficiency heat conduction circuit board according to claim 1, wherein the conductive contact (4) is a metal selected from the group consisting of copper, silver, zinc, titanium and tungsten.   The high efficiency heat conduction circuit board according to claim 5, wherein the conductive contact is made of copper. A method for manufacturing a high-efficiency heat conduction circuit board for electrically connecting electronic components (5),
(A) placing the metal substrate (2) in an electrolytic cell;
(B) oxidizing the metal substrate (2) in the electrolytic cell and forming a metal oxide layer (3) thereon by microarc oxidation;
(C) forming a plurality of conductive contacts (4) for electrically connecting the electronic component (5) on the metal oxide layer.   The method according to claim 7, wherein the conductive contact (4) is formed by cathodic arc plasma ion plating in the step (c).   The method according to claim 7, wherein the metal substrate (2) is made of a metal selected from the group consisting of aluminum, titanium, magnesium, zirconium, beryllium, tantalum and alloys thereof.   The method according to claim 9, wherein the metal substrate (2) is made of aluminum.   The manufacturing method according to claim 7, wherein the electrolytic cell contains an aqueous ammonia solution. The aqueous ammonia solution is a water soluble salt selected from the group consisting of phosphates, chromates, silicates, carbonates and mixtures thereof;
The production method according to claim 11, further comprising a conductive auxiliary agent capable of being ionized into acetate ions.   The electrolytic cell comprises 0.3 to 0.6 mol / liter potassium dihydrogen phosphate, a concentration of 0.08 to 0.3 mol / liter potassium chromate, and a concentration of 0.08 to 0.5 mol / liter. 13. The process according to claim 12, comprising 2 to 6 volume percent aqueous ammonia solution with 1 liter acetate ion.   The method according to claim 13, wherein the conductive additive is copper acetate.   The method according to claim 7, wherein the oxidation of the metal substrate (2) in the electrolytic cell is performed in a temperature range of 0 ° C to 150 ° C.   The manufacturing method according to claim 15, wherein the temperature is in the range of 0 ° C. to 40 ° C.

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