WO2012148020A1

WO2012148020A1 - Method for forming a nanodiamond-impregnated dielectric layer for a highly heat dissipating metal substrate

Info

Publication number: WO2012148020A1
Application number: PCT/KR2011/003177
Authority: WO
Inventors: 김동규; 김현수; 황영찬; 손재구
Original assignee: 주식회사 이넥트론
Priority date: 2011-04-28
Filing date: 2011-04-28
Publication date: 2012-11-01
Also published as: KR20130016457A

Abstract

The present invention relates to a method for forming a dielectric layer having an improved heat-dissipating performance and dielectric performance by impregnating nanodiamond into the dielectric layer of an existing metal heat-dissipating substrate in order to improve the heat-dissipating ability of the dielectric layer. More specifically, an anodisation method is introduced so as to form an anodic film as a dielectric layer on at least one surface of an aluminium or aluminium alloy or a magnesium or magnesium alloy plate material provided as a metal heat-dissipating plate, and then an acid or an alkali is used so as to expand voids in the anodic film, and conditioning is carried out in order to ensure that the insides of the expanded voids are hydrophilic. Also, a method is provided for forming a nanodiamond-impregnated dielectric layer for a highly heat dissipating metal substrate, the method comprising the step of impregnating the expanded voids with nanodiamond.

Description

Method of forming insulating layer of nano diamond impregnated high heat dissipation metal substrate

The present invention relates to a high-efficiency LED metal heat dissipation substrate and a method of manufacturing the same, and more particularly, to improve heat dissipation capability of the insulating layer in the existing metal heat dissipation substrate by impregnating the nano-diamond in the insulating layer to improve heat dissipation performance and insulation performance It relates to a method for forming an insulating layer.

Until recently, LED devices were mainly used for indicator purposes (display purposes), and since high heat dissipation was not required, resin-based (FR-4) substrates have been used as substrates on which LEDs are mounted. Since 2000, the LED's high brightness, high efficiency, and especially the blue LED device has been significantly improved, and the attempt to examine its applicability in LCD, home appliances, and electronic fields has been accelerated. The area of reviewing the range of applications has also expanded due to the rapid penetration of digital home appliances and flat panel displays (FPD) and the cost savings of LED alone. In addition, as the company sponsors this trend, the European Union's RoHS ban on harmful substances has made it clear that the trend of technology trend from CCFL (cold cathode tube) to LED is becoming clear. The demand for is also growing.

As high power and high brightness LEDs are deployed in various devices as described above, heat dissipation measures for products mounted with LEDs are being highlighted. High heat dissipation substrates with excellent price / performance ratios have attracted attention as substrates for power LEDs, and many studies have been conducted in advanced countries.

In general, the substrate on which the LED is mounted may be divided into a resin substrate, a ceramic substrate, and a metal substrate. In the case of an epoxy resin (FR-4) -based substrate, it is not suitable as a high heat dissipation substrate, and a ceramic substrate or a metal substrate is attracting attention as a high heat dissipation substrate. In the case of a ceramic substrate (eg, SiC, thermal conductivity is 170W / m · K), it can be said to be very advantageous in terms of heat dissipation effect, but it is difficult to manufacture, low productivity, and high cost. Therefore, an aluminum (alloy) metal substrate (e.g., a thermal conductivity of pure Al of 230 W / m · K), which is cheaper than a ceramic substrate and has good recycling properties, is generally used as a power LED substrate.

1 is a metal PCB structure most used in the conventional power LED field. Aluminum (alloy), which is a metal material, is used as the heat dissipation layer, and synthetic resin material is used as the insulating layer thereon. An electrically conductive layer is formed on the insulating layer. As the electrically conductive layer, a Cu foil having good electrical conductivity is generally used. The problem of the above structure is in the insulating layer, because the heat dissipation layer and the electrically conductive layer is a metal, the heat dissipation performance is good, but there is a limit to the heat dissipation performance because the insulating layer located in the middle is made of synthetic resin material. Therefore, the current thermal conductivity of commercially available synthetic resin materials (1.8W / mK, Japan Panasonic Electric Device) is much lower than the metal, so the ability of the metal heat dissipation layer is not fully utilized.

FIG. 2 is a structure of another conventional metal PCB developed for improving the performance of FIG. 2. In FIG. 2, unlike the case of FIG. 1, an aluminum oxide surface is anodized and used as an insulating layer without using a synthetic resin as an insulating layer. The insulating layer secured by anodizing treatment has a heat dissipation performance superior to that of the synthetic resin material with a thermal conductivity of about 70 W / m · K. However, since the metal layer used as the electrically conductive layer is formed in a paste type, the resistance value is much higher than that of a single metal (Cu foil), thus making it difficult to implement a fine pattern.

Since heat dissipation is the most important issue in LED packages, ceramics are commonly used in current LED packages. However, expensive raw materials are used in aluminum nitride (AlN) packages, leading to higher product prices. Therefore, it is difficult to build a price competitiveness with ceramic substrates in lighting and home appliances.

In Japan, which is known as the originator of LEDs, the demand for high-efficiency LED products is increasing by more than 20% every year. In 2009, the LED was developed in the LCD TV field, and in 2010, LED lighting began to develop in earnest, and lighting companies are actively producing LED lighting. Japan is also a major technical issue in LED development, which is a heat dissipation measure for products equipped with high power LEDs. In particular, the deterioration of the lifespan and luminance of the LEDs due to heat generation are important tasks. Therefore, the demand for high heat dissipation substrates is increasing.

In Japan, the LED package is classified as the power consumption of the LED. In low power LEDs that do not require heat dissipation measures, a resin substrate such as a FR-4 substrate and a plastic lead chip carrier (PLC) package having a conventional structure Is used. In addition, a heat sink package and a metal base substrate are used in a power LED of 1 W or more, and an alumina substrate and an aluminum nitride substrate are used in a high power LED of 3 W or more.

As the high power LED market continues to grow, the demand for high heat dissipation substrates increases, so it is time for continuous product development.

The present invention is therefore to provide a technique for replacing the synthetic resin insulating layer which is located between the metal heat dissipation layer and the metal conductive layer in the metal PCB to hinder the heat dissipation performance in order to solve the problems of the prior art and cope with the increase in demand. In order to provide a technique for improving the heat dissipation performance and insulation performance of the anodized film used as an insulating layer in the existing metal PCB, to provide a method for forming an insulating layer of a high heat-resistant metal substrate impregnated with nanodiamonds. There is this.

The present invention seeks to overcome the fundamental limitation of the heat dissipation effect that can be obtained by changing the existing heat dissipation substrate structure. In order to overcome the limitations of the heat transfer capability of the material constituting the existing heat radiation board, nano diamond is applied to improve heat transfer properties of the heat radiation board itself.

The present invention provides an insulating layer on one surface of an aluminum substrate through an anodizing treatment to solve the existing resin-based insulating layer to inhibit the heat dissipation characteristics of the existing resin-based material in the nano-sized pores formed in the anodizing film The objective is to secure an insulating layer that significantly improves heat dissipation performance and insulation performance by impregnating nano-sized diamond (thermal conductivity 900 ~ 2,000W / m · k) with the best thermal conductivity.

In order to achieve the above object of the present invention, the present invention introduces an anodizing method on at least one surface of at least one metal heat sink plate selected from aluminum, aluminum alloy, magnesium, and magnesium alloy to form an anodizing film as an insulating layer. Making a step (S1);

Expanding the pores of the anodizing film using acid or alkali after step S1;

Conditioning to ensure hydrophilicity in the expanded pores (S3); And,

After the step (S3) provides a method for forming an insulating layer of nano-diamond-impregnated high heat dissipation metal substrate comprising the step (S4) of impregnating nanodiamonds with expanded pores.

In the above, the conditioning in the step (S3) may use a surfactant having a HLB (Hydrophile-Lipophile Balance) value of 10 or more, because it is advantageous to secure the hydrophilicity in the pores. In addition, the pores in the step (S2) is preferably to be expanded to at least 30nm or more, because the pores should be at least 30nm or more can be sufficiently impregnated with 4 ~ 20nm size nanodiamonds in the post-process.

In addition, the nano-diamond particles in the step (S4) is preferably made to be 4 ~ 20nm size, the commercialized minimum size is 4nm, when more than 20nm impregnation rate is lowered, unimpregnated is accumulated on the surface Since there is no impregnation effect, it is set as the said range. The impregnation in the step (S4) is preferably impregnated one or more times while stirring for 1 minute to 10 hours in consideration of the film thickness at a temperature of 80 ℃ or less, the temperature at which the pores are not closed in the nanodiamond dispersion aqueous solution of 10wt% or less. .

When the diamond content is more than 10wt%, the density of the diamond is increased and the impregnation rate is lowered. That is, since the water in the aqueous solution plays a role to move the diamond to the inside of the pores, when the density of the diamond is increased, the movement of water is increased. The path is constrained, making it difficult to deliver diamonds into the pores.

In addition, the impregnation may be performed within a few minutes while operating an ultrasonic wave of 40 ~ 100khz intermittently. The ultrasonic effect can not be expected below 40khz and stress above the anodizing film above 100khz and the impregnation rate may be lowered as above.

In addition, the said impregnation can also be performed under the vacuum state below atmospheric pressure.

According to the present invention, the anodizing film formed through the chemical structural modification of the metal heat dissipation layer can perform the function of an insulator, and impregnate nano diamonds in the nano pores formed in the anodizing film to improve insulation and heat dissipation at the same time. The composite insulation layer can be secured. Therefore, according to the present invention, by providing a technology that can significantly improve the heat dissipation performance of the existing resin-based insulating layer it is possible to significantly improve the life and reliability of the high-power LED. In addition, by improving the physical properties of the existing anodizing film it is possible to secure an improved insulating layer.

1 is a conventional metal PCB structure

2 is another conventional metal PCB structure

3 is a substrate structure according to an embodiment of the present invention

4 is a substrate structure according to Comparative Example 1

5 is a substrate structure according to Comparative Example 2

6 shows nanopores (before pore expansion) of anodizing film surface

7 shows the film surface nanopores after pore expansion

8 is anodizing film cross section (before nano diamond impregnation)

9 is anodizing film cross section after the impregnation process (nano diamond impregnation confirmed)

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings and examples. The following examples are intended to be easily described by those of ordinary skill in the art, but the present invention is not limited thereto.

The metal heat sink used in the present invention uses aluminum, an aluminum alloy (hereinafter aluminum), or a magnesium or magnesium alloy (hereinafter magnesium) plate material. Aluminum and magnesium vary depending on the type of alloy, and the present invention is not bound to the type. The thickness of the board is 0.4 ~ 10mm, so the thickness can be selected according to the specifications of the heat sink board that the user wants. There is no boundary for the thickness.

The present invention is related to the insulating layer forming process of the existing metal radiating substrate manufacturing process has its technical features. Processes that are performed before / after the insulating layer formation may proceed to existing manufacturing processes, and the present invention does not limit the methods. In the present invention, there is a technical feature in the process of impregnating nanodiamonds in the nanopores of the film after the anodizing film is formed.

An aluminum or magnesium plate is prepared with a metal heat sink and anodized film is formed on at least one surface through anodization. The anodization method proceeds with a conventional well-known technique, and the present invention does not limit the method. After the anodization process, an anodizing film is formed to form an insulating layer. The coating itself can serve as an insulating layer, but the present invention is intended to improve the function of the existing insulating layer by impregnating nanodiamonds into the anodizing film, and to replace the existing resin-based insulating layer. Referring to the process of impregnating Nano diamond which is a technical feature of the present invention in detail.

[Pore expansion process]

After anodizing, the surface of the anodizing film, which is an insulating layer, has a large number of pores of about 20 nm in diameter. The depth of these pores is proportional to the thickness of the anodizing film. The present invention is to expand the pore size by impregnating the nanodiamond powder having a diameter of 20nm or less inside the pore to significantly improve the heat dissipation ability and insulation ability. For pore expansion, an acid or alkali selected from phosphoric acid, hydrofluoric acid, sodium hydroxide and potassium hydroxide is used to expand the pore of the anodizing film. The pore size is extended to at least 30 nm to impregnate nanodiamonds less than 20 nm.

[Conditioning process]

It is a process to secure the hydrophilicity inside the pores in order to impregnate the nano diamond inside the expanded pores. In the conditioning process, a surfactant having a hydrophile-lipophile balance (HLB) value of 10 or more is used.

[Impregnation process]

It is a process of impregnating nanodiamond of size less than 20nm in the pores expanded more than 30nm. Looking at the domestic patent (Application No. 10-2009-0065448) that impregnates diamond into a metal substrate during the manufacture of a heat dissipation substrate, the diamond powder is dispersed on the metal substrate, pressurized with a roll or a press to press the diamond powder into the metal substrate, It is explained that a diamond coating film coated by a synthetic method is deposited on particles of diamond powder exposed on a surface of a metal substrate to grow, thereby forming a coating film for heat dissipation and insulation. Products manufactured with the above technology have not been introduced on the market yet, so it has not been known how much its performance is. However, in order to make a heat radiation board with the above technology, expensive production equipment is required, which may lead to an increase in product cost.

Therefore, in the present invention, a wet surface treatment method has been introduced to effectively impregnate diamond with nanopores without using expensive equipment. A method of impregnating at least one time with stirring for 1 minute to 10 hours at 80 ° C. or less in a 10 wt% or less nanodiamond dispersion solution. The treatment time can be adjusted according to the thickness of the anodizing film. Important during the impregnation process is continuous mechanical agitation so that the nanodiamonds can be dispersed in the process solution. In this process, the ultrasonic device can be used to more effectively impregnate the nanodiamond, and in this case, the ultrasonic wave is preferably operated periodically for about 10 to 30 seconds every 2 to 8 minutes at about 40 to 100 KHZ. If the ultrasonic wave is continuously operated, the impregnation efficiency is rather deteriorated. In addition, the impregnation process may be improved by performing the impregnation process at the same time as the above conditions under a vacuum condition, but there is no problem in diamond impregnation even without using a low vacuum condition.

After finishing the impregnation process as described above to proceed to the rest of the process to complete the metal radiating substrate. Subsequently, the process of forming an electrically conductive layer on the insulating layer is performed by using a metal paste printing technique and an electroless plating technique, a method using an electroless plating and an electrolytic plating, a method using a dry coating technique using a vacuum equipment, and a resin system. There exists a method of laminating | stacking copper foil (RCC) using an adhesive layer. Such a conductive layer forming method is not limited in the present invention as a conventionally invented or commercialized technology.

Impregnating nanodiamonds into the existing anodizing film according to the present invention improves the heat dissipation and insulating properties of the existing anodizing film by about 5 to 20%, and improves the heat dissipation properties in terms of heat dissipation properties by several orders of magnitude.

Performance evaluation was performed on products made through Examples and Comparative Examples. The heat dissipation performance was confirmed by the thermal conductivity measurement, and the insulation performance was confirmed by the withstand voltage measurement.

EXAMPLE

In this embodiment, an anodizing film having a thickness of about 40 μm was formed by using an anodizing method on an aluminum plate having a thickness of 1 mm, followed by an impregnation process. In order to impregnate the nano-pores formed in the anodizing film, a pore expansion process was performed. An aqueous solution containing 4 mL / L hydrofluoric acid (40%) was prepared and the process temperature was maintained at 25 ° C. After the prepared substrate was immersed in the process solution for about 20 seconds to carry out the pore expansion process, water washing was sufficiently performed, and a conditioning process for securing hydrophilicity inside the pores was performed. A process solution consisting of 4 g / Lt of sodium lauryl sulfate was prepared and the solution temperature was maintained at about 25 ° C. The substrate prepared after the previous process was immersed in the process solution for 10 minutes to perform the conditioning process, washed with water and dried sufficiently to proceed with the impregnation process. As the impregnation conditions, first, 1 wt% of nanodiamonds were dispersed in water to prepare a process solution, the temperature was maintained at 30 ° C., and the substrate having been subjected to the previous process was immersed in the process solution for 60 minutes to perform an impregnation process. During the impregnation process, ultrasonic waves were performed at 40khz for 15 seconds every 5 minutes, and the process solution was mechanically stirred to maintain the dispersion of nanodiamonds. After the impregnation process, a conductive paste was completed by electroless Ni / Au plating after pattern formation with Ag paste in a conventional manner.

Comparative Example 1

In Comparative Example 1, only an anodizing film having a thickness of about 40 μm was formed on one surface of an aluminum plate having a thickness of 1 mm by the conventional anodizing method as in Example, and then a pattern was formed by Ag paste using a conventional method, followed by electroconductivity by electroless Ni / Au plating. The layer was completed.

Comparative Example 2

In this case, we used a metal heat dissipation board produced by domestic D company. Currently, it is generally known that the heat dissipation characteristics of the substrate are generally better than that of the insulating layer provided by the present invention because the substrate is used in the field of LED but the resin-based insulating layer is used.

Table 1

division	Example-1	Comparative Example-1	Comparative Example-2
Thermal Conductivity (W / mK)	152	135	2
Dielectric BreakdownVoltage (AC, KV)	above 3.5	above 3.0	above 3.0

Looking at the performance comparison Table 1 it can be seen that the embodiment of the present invention impregnated with diamond is significantly improved than the comparative example conditions in the thermal conductivity and withstand voltage characteristics.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims You will understand.

Claims

Forming an anodizing film as an insulating layer by introducing an anodization method on at least one surface of an aluminum, aluminum alloy or magnesium or magnesium alloy sheet material prepared with a metal heat sink;

Expanding the pores of the anodizing film by using an acid or an alkali after the step (S1);

Conditioning to ensure hydrophilicity in the expanded pores (S3); And,

Method of forming an insulating layer of nano-diamond-impregnated high heat dissipation metal substrate, characterized in that it comprises a step (S4) of impregnating nanodiamonds with expanded pores after the step (S3).
The method of claim 1, wherein the conditioning in the step (S3) is a method of forming an insulating layer of nano-diamond-impregnated high heat-dissipating metal substrate, characterized in that using a HLB (Hydrophile-Lipophile Balance) value of 10 or more surfactant.
The method of claim 1, wherein the pores in the step (S2) is extended to at least 30nm or more.
The method of claim 1, wherein the nano-diamond particles in the step (S4) is 4 ~ 20nm size of the nano-diamond-impregnated high heat dissipating metal substrate.
The method of claim 1, wherein the impregnation in step (S4) is impregnated with nano-diamond impregnated high heat-dissipating metal, characterized in that the impregnation of the nanodiamond dispersion solution of less than 10wt% 1 minute to 10 hours or less while stirring. Method of forming an insulating layer of a substrate.
The method of claim 1, wherein the impregnation is performed within several minutes while operating an ultrasonic wave of 40 to 100 kHz intermittently.
7. The method for forming an insulating layer of a nanodiamond-impregnated high heat-dissipating metal substrate according to any one of claims 5 and 6, wherein the impregnation is performed under a vacuum at atmospheric pressure or lower.