KR101380774B1 - Method of preparing conducting layer of metal plate - Google Patents

Abstract

Disclosed is a method of forming a conductive layer of a metal substrate using a metal heat dissipation substrate with high heat dissipation. The present invention comprises a step of forming an anodizing film as an insulation layer on at least one surface of one metal heat dissipation board selected from aluminum, aluminum alloys, magnesium, and magnesium alloys by adopting an anodic oxidation method; a step of forming a paste metal layer on the anodizing film with a printing method and solidifying the paste metal layer by heat treatment; a step of forming a cross-section in a thin semi-elliptical shape by using a chemical etching method using a paste washing solution for the irregular cross-section of the solidified paste metal layer; and a step of performing drying after the chemical etching process.

Description

Method for preparing conducting layer of metal plate using high heat radiation metal radiating substrate

The present invention relates to a method for forming a conductive layer of a metal substrate when manufacturing a metal heat dissipation substrate for high efficiency LED, and more particularly, to form a paste-type metal layer using a metal printing method after forming an insulating layer through anodizing on one surface of an existing metal substrate; In order to improve the peeling phenomenon of the metal film due to the stress between the paste-type metal layer and the conductive layer during the formation of the conductive layer, after the formation of the paste-type metal, some etching methods are used to control the cross-section of the paste-type metal layer and to control the shape of the conductive layer formed thereon. The present invention relates to a method for forming a conductive layer of a metal substrate using a high heat dissipating metal heat-dissipating substrate which improves the adhesion between the two layers by reducing stress, thereby improving the peeling phenomenon of the metal film or the cracking of the conductive layer.

Until recently, LED devices were mainly used for indicator purposes (display purposes), and since high heat dissipation was not required, a resin based substrate (FR-4) substrate has been used as a substrate on which LEDs are mounted. Since 2000, LED's high brightness, high efficiency, and especially blue LED devices have been significantly improved, which has accelerated application and development in LCD, home appliances, and electronic fields. 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. Epoxy resin (FR-4) -based substrates are not suitable as a high heat dissipation substrate, and a ceramic substrate or a metal PCB has attracted attention as a substrate on which high heat dissipation LEDs having high thermal conductivity are mounted. In the case of a ceramic substrate (eg, SiC, thermal conductivity is 170W / m?), It can be said to be very advantageous in terms of heat dissipation effect, but it is difficult to manufacture, has low productivity, and high unit cost. Therefore, an aluminum (alloy) metal substrate (eg, a thermal conductivity of pure Al of 230 W / m?), Which is cheaper than a ceramic substrate and has good recycling and thermal conductivity, is generally used as a power LED substrate.

1 is a metal PCB structure most used in the conventional power LED field. Aluminum (alloy) 1, which is a metal material, is used as the heat dissipation layer, and synthetic resin material is used as the insulating layer 2 thereon. An electrically conductive layer 3 is formed on the insulating layer, and as the electrically conductive layer 3, generally a copper foil having good electrical conductivity is used. The problem of the above structure is in the insulating layer 2, since the heat dissipation layer and the electrically conductive layer are 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 (1.8W / m ?, Panasonic Electro-Lac Devices, Japan) of commercially available synthetic resin material is much lower than that of the metal, so the ability of the metal heat dissipation layer is not fully utilized.

Figure 2 is a structure of another conventional metal PCB developed for improving the performance of FIG. In FIG. 2, unlike the case of FIG. 1, the aluminum surface 5 is anodized and used as the insulating layer 6 without using a synthetic resin material as the insulating layer. The insulating layer 6 secured by anodizing has a thermal conductivity of about 70 W / m? The heat dissipation performance is much better than that of synthetic resin materials, and the price is cheaper than that of ceramic substrates. Since the metal layer 7 used as an electrically conductive layer is formed in a paste type, the resistance value is much higher than that of a single Cu foil, and thus the conductive layer (Ni-B is formed by electroless plating thereon). Or Cu layer) (8). However, after the copper conductive layer is formed, as shown in FIG. 4, the peeling or cracking of the conductive layer occurs due to the stress between the paste layer and the conductive layer at the end of the pattern, resulting in poor conductivity, which makes it difficult to construct a production technology. to be.

The silver paste metal layer 12 formed by the printing method according to the prior art is formed on the aluminum layer 10 and the anodized aluminum layer 11, as shown in Figure 3, the silver paste metal layer (12) is formed in the angular form of the end of the cross section, which is a problem caused by the printing method, or leaves some printed residue 13.

However, as shown in FIG. 4, the angular shape or the print residue 13 at the end of the cross section causes the formation of the conductive layer 14 to be formed later, and the stress in the subsequent process. Peeling phenomenon 15 or cracking phenomenon 16 of the conductive layer 14 of the angled portion may be caused.

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, 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.

Therefore, 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 of high heat dissipation LED substrates with excellent heat dissipation and cost competitiveness.

An object of the present invention is to solve the above problems, to prevent the peeling phenomenon of the metal film due to the stress appearing between the printed metal layer (paste-type metal layer) and the conductive layer of the metal substrate when manufacturing a high-efficiency LED metal radiating substrate. The present invention provides a method for forming a conductive layer of a metal substrate using a high heat dissipating metal heat dissipation substrate.

In order to achieve the above object, a method of forming a conductive layer of a metal substrate using a high heat-radiating metal heat dissipation substrate according to the present invention,

Forming an anodizing film as an insulating layer by introducing an anodization method on at least one surface of a metal heat sink plate selected from aluminum, aluminum alloy, magnesium and magnesium alloy;

Forming a paste metal layer on the anodizing film by a printing method and performing heat treatment to solidify the paste metal layer;

Forming an irregular cross section of the solidified paste metal layer into a thin semi-elliptic cross section using a chemical etching method using a paste cleaning solution; And

After the chemical etching process is completed, performing a drying; characterized in that it comprises a.

The paste metal layer may be formed of silver (Ag) paste or copper (Cu) paste.

The paste cleaning solution is a chemical solution containing water, a surfactant, and a performance enhancer, and has a hydrogen ion index of 5 to 9 pH.

In the process conditions of the chemical etching method, the temperature is 0 ~ 90 ℃, the time is characterized in that proceeding within 24 hours.

According to the present invention, in the case of the metal layer (paste metal layer) proceeded by the printing method, an irregular cross section appears, which is removed by using a chemical etching method using a paste cleaning solution, and at the same time the entire cross section of the paste metal layer is removed. Is formed in a semi-ellipse shape to reduce stress with a subsequent conductive layer (e.g., electroless plating layer), thereby eliminating delamination between two metal layers and cracking in the conductive layer, thereby greatly improving the lifetime and reliability of a high-power LED. You will get the effect you can get.

1 is a structural diagram of a conventional metal PCB.
Figure 2 is another conventional metal PCB structure diagram.
3 is a schematic cross-sectional view of a conventional printed metal layer.
Figure 4 is a schematic cross-sectional view of the entire metal layer formed using a conventional printed metal layer.
5 is a schematic cross-sectional view of the printed metal layer according to an embodiment of the present invention.
Figure 6 is a schematic cross-sectional view of the entire metal layer formed using a printed metal layer according to an embodiment of the present invention.
FIG. 7 is a SEM photograph cross section showing photographs of metal cracking occurring in a paste-printed metal layer and a conductive layer in a conventional metal PCB structure.
FIG. 8 is a cross-sectional view of a SEM photograph, in which a peeling phenomenon due to stress appearing in a paste-printed metal layer and a conductive layer in a conventional metal PCB structure is taken.
FIG. 9 is a cross-sectional SEM photograph showing photographs of a cross-sectional shape of a paste printed metal layer and a conductive layer in a metal PCB structure according to an exemplary embodiment of the present invention.

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 present invention forms a metal substrate having a metal and a non-conductor having excellent thermal conductivity, and then forms a paste metal layer by a metal printing method for patterning a conductive material, and then adds an etching process using an etching solution to form a cross-sectional shape of the paste metal layer. By controlling the pressure, the paste metal layer, the electroless plated conductive layer, or the insulating layer (anodizing valve) formed in the process of forming the conductive layer by the subsequent electroless plating method or in the subsequent process conditions (heat treatment or chemical treatment process) and The peeling phenomenon with the electroless plating layer and the cracking phenomenon of the electroless plating layer (see FIG. 4) can be eliminated.

Referring to FIG. 5, the present invention provides an anodizing film 21 as an insulating layer by introducing an anodization method on at least one surface of a metal heat sink plate member 20 selected from aluminum, aluminum alloy, magnesium, and magnesium alloy. ).

The anodizing film 21 paste metal layer is formed by a printing method and heat treated to solidify the paste metal layer 22. The paste metal layer 22 uses silver (Ag) paste, copper (Cu) paste, or the like.

An irregular cross section of the solidified paste metal layer 22 is formed into a thin semi-elliptic cross section using a chemical etching method using a paste cleaning solution.

The paste cleaning solution is preferably a chemical solution containing water, a surfactant, and a performance improving agent, and has a hydrogen ion index of 5 to 9 pH. If it is out of this range, the aluminum (alloy) or magnesium (alloy) used as the substrate may be damaged.

In addition, in the process conditions of a chemical etching method, it is preferable that temperature is 0-90 degreeC and time advances within 24 hours.

If the temperature is high or the time becomes long, the paste cleaner may damage the anodizing film 21 used as the insulating layer and may cause peeling between the film 21 and the silver paste layer 22.

After the chemical etching step is completed, drying is performed.

The metal heat sink referred to 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 plate is about 0.4 to 10mm, the user can select the thickness according to the heat radiation board specifications desired by the user, there is no boundary for the thickness.

The present invention relates to a paste-type metal layer (or conductive layer) forming process to be formed by a printing method of the existing metal radiating substrate manufacturing process has its technical features. The printing metal layer and the processes proceeding before / after formation on the metal layer may proceed to existing manufacturing processes, and the present invention does not limit the methods. In the present invention, after forming the paste-type metal layer film formed by the printing method, the cross-section of the metal layer is etched through the etching method, so that the cross-section of the paste-type metal layer according to the embodiment of the present invention shown in FIG. The technical features of the process to have a.

An aluminum or magnesium plate is prepared as a metal heat sink and anodizing film 21 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. Thereafter, a paste-type metal layer is formed by a printing method. The paste-type metal layer is also not limited to the method in the present invention. Forming a copper metal layer alone does not yield the desired conductivity, requiring the selective production of a new conductive layer only on the copper conductive layer.

According to the present invention, the cross section of the paste metal layer formed by the printing method has a semi-elliptic cross section by a chemical etching method, thereby reducing the stress of the conductive layer (23: electroless plated layer) formed thereafter. The purpose of the present invention is to greatly improve the service life and reliability of the conductive layer by eliminating the peeling phenomenon between the metal layers and cracking in the conductive layer.

As a liquid used for chemical etching of the paste metal layer, a neutral chemical solution (5 to 9 pH) is used so as not to damage the aluminum or anodized aluminum layer used as the substrate.

The process of chemical etching at this time is carried out under a relatively low temperature of 90 ° C. and within 24 hours so as not to damage the aluminum or anodized aluminum layer used as the substrate. This is because, as described above, if the temperature is high or used for a long time, the aluminum, aluminum alloy, magnesium, and magnesium alloy used as the substrate may be damaged.

After completing the chemical etching process as described above, the rest of the process proceeds to complete the metal printed board. The process may be a method using an electroless plating technique as shown in FIG. 6, but if necessary, a method of using a dry coating technique using a vacuum installation, a method of laminating a copper foil (RCC) using a resin adhesive layer, or the like may be used. It may be. Such a conductive layer forming method is not limited in the present invention as a conventionally invented or commercialized technology.

FIG. 7 is a SEM photograph cross section, which is a photograph of a metal split phenomenon occurring in a paste printed metal layer and a conductive layer in a conventional metal PCB structure, and FIG. 8 is a SEM photograph cross section, in which a paste print appears in a conventional metal PCB structure This is a photograph of peeling phenomenon caused by stress in the metal layer and the conductive layer.

As shown in Fig. 7 and 8, the angular shape of the end of the cross-section is part of the delamination of the anodized film or the conductive layer of the angular portion due to the formation of the conductive layer formed later and the stress caused in the subsequent process This may cause cracking.

By adjusting the cross-section of the paste metal layer formed by the printing method according to the present invention to have a semi-elliptic cross-section by chemical etching method, the stress formed with the conductive layer 23 formed thereafter is reduced as shown in FIG. 9. As a result, the peeling phenomenon between the two metal layers and the cracking phenomenon in the conductive layer are eliminated, thereby greatly improving the lifetime and reliability of the conductive layer.

20: metal heat sink plate 21: anodizing film
22: paste metal layer 23: conductive layer

Claims (4)

Forming an anodizing film as an insulating layer by introducing an anodization method on at least one surface of a metal heat sink plate selected from aluminum, aluminum alloy, magnesium and magnesium alloy;
Forming a paste metal layer on the anodizing film by a printing method and performing heat treatment to solidify the paste metal layer;
Forming an irregular cross section of the solidified paste metal layer into a thin semi-elliptic cross section using a chemical etching method using a paste cleaning solution; And
After finishing the chemical etching method comprising the step of performing a drying;
In the chemical etching method, the paste cleaning solution is a chemical solution containing water, a surfactant, and a performance enhancer, and has a hydrogen ion index of 5 to 9 pH. Way. The method of claim 1,
The paste metal layer comprises a silver (Ag) paste or a copper (Cu) paste, the method of forming a conductive layer of a metal substrate using a high heat-radiating metal heat dissipation substrate, characterized in that. delete The method of claim 1,
In the process conditions of the chemical etching method, the temperature is 0 ~ 90 ℃, the time is carried out within 24 hours, the method of forming a conductive layer of a metal substrate using a high heat-radiating metal heat dissipation substrate.

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