KR20090040374A - Back panel of LED device and liquid crystal display device - Google Patents

Abstract

The LED device of the present invention comprises a substrate 102 comprising Cu and / or Al, a diamond-like carbon layer 106 disposed on the substrate; An electrical circuit 108 formed on the diamond-like carbon layer; And an LED chip 110 electrically connected to the electrical circuit. LED can be used as a light source of the backlight of the liquid crystal display device.

Description

LED device and back panel of liquid crystal display

The present invention relates to a light emitting diode (LED). The LED of the present invention can be used for a back panel of a liquid crystal display (LCD).

LED is expected as a next-generation light source. Possible applications of LEDs include lighting, back light in liquid crystal displays, display devices in instrument panels in automobiles, optical disks, and the like.

When LEDs are used in electrical devices, it is necessary to solve the problems caused by heat. The temperature of the LED chip can increase significantly when a large amount of power is supplied.

When a large amount of power is supplied to a perhaps small mounting area of the light source, there is a risk that the LED chip can store heat and increase in temperature. Moreover, even when this heat is transferred to a thermally conductive substrate on which the LED chip is mounted, the substrate stores heat to increase the temperature, and thus there is a risk that the temperature of the LED chip may also increase.

In order for the LED lighting device to efficiently emit a large amount of light, it is necessary to properly dissipate heat generated in the LED chip to the outside to prevent the temperature of the LED chip from excessively increasing.

US Patent Application Publication 2005-276052 discloses an illumination system in which diamond-like carbon (DLC) is disposed for heat diffusion on ceramic surfaces such as AIN, GaN or SiC.

However, there are still many demands on the LED device, especially when the LED device is used in display applications such as the backlight of LCDs. These requirements include (1) higher thermal conductivity, (2) reduction in production costs, and (3) application to large sizes.

Summary of the Invention

It is an object of the present invention to provide an LED device in which the substrate of the LED device has a high thermal conductivity, the LED device can be produced economically, and an LED device having a large area can be easily produced.

One embodiment of the invention provides a substrate comprising Cu and / or Al, a diamond-like carbon layer disposed on the substrate, an electrical circuit formed on the diamond-like carbon layer, and mounted on the substrate and electrically connected to the electrical circuit. LED device including an LED chip.

Another embodiment of the present invention is a back panel of a liquid crystal display device, and the LED device is used as a light source.

The present invention provides a method comprising: providing a substrate comprising Cu and / or Al, providing a diamond-like carbon layer disposed on the substrate, forming an electrical circuit formed on the diamond-like carbon layer, and electrical powering the LED chip. There is further provided a method of forming an LED device comprising the step of electrically connecting to a circuit.

Substrates made of metals or alloys such as copper or aluminum or alloys thereof can be easily produced at low cost. In addition, these metal or alloy materials have higher thermal conductivity than ceramics. Moreover, large LED panels can be easily manufactured using metal or alloy substrates. This effect is very beneficial in display device applications, such as liquid crystal display (LCD), where the panel size continues to increase.

In addition, diamond-like carbon is disposed on the surface of the substrate, resulting in high thermal conductivity due to effective heat dissipation and conduction by the DLC.

1 is a diagram of an embodiment of an LED device of the present invention.

2 is a view of another embodiment of the LED device of the present invention.

3 is a view of another embodiment of the LED device of the present invention.

The present invention is capable of mass production for high thermal conductivity, low cost, and large area by using Al and / or Cu as the substrate and diamond phase carbon (DLC) as the inner layer between the substrate and the electrical circuit connected to the LED chip. And the ease of handling.

The thermal conductivity of GaN, AIN and SiC is 130 W / m-K, 170-230 W / m-K and 120 W / m-K, respectively, while the thermal conductivity of AI and Cu is 150-230 W / m-K and 400 W / m-K, respectively. By using a metal or alloy having high thermal conductivity, the thermal management performance of the LED device can be enhanced.

In general, the production cost of metal or alloy plates is not expensive. This means lower material costs, resulting in lower device costs for LED devices. Because of the mechanical strength of the metals and alloys (toughness that is not brittle like ceramics), it is much easier to process metal or alloy substrates such as cutting, resulting in lower manufacturing costs. In addition, it is much easier to manufacture metal or alloy substrates on a large scale, and the ceramic panel size is typically limited to 29 cm 2 (4.5 square inches).

The LED device of the present invention provides a substrate comprising, for example, Cu and / or Al, forms a DLC layer on the substrate, forms an electrical circuit on the DLC layer, forms an electrical circuit on the DLC layer, It can be manufactured by mounting an LED chip and electrically connecting the LED chip to an electrical circuit.

1. Substrate

Substrates of the invention comprise Cu and / or Al. The substrate may be an Al plate, Cu plate, Al-containing alloy plate or Cu-containing alloy plate. In the present invention, a conductive substrate can be used. If the substrate contains Al, the surface in the direction of the DLC layer is preferably anodized with oxygen.

Al-containing alloys include, but are not limited to, Al-Cu, Al-Mn, Al-Si Al-Mg, Al-Mg-Si, Al-Zn-Mg, and Al-Zn-Mg-Cu. Cu-containing alloys include Cu-Ni, Cu-Ni-Si, Cu-Sn, Cu-Cr-Zr-Zn, Cu-Fe-P, Cu-Ni-Sn-P, Cu-Mo, Cu-Co, Cu-Fe, Cu-Cr, Cu-Mo-Ni, Cu-Mo-Cr, Cu-Mo-Co, and Cu-Mo-Fe.

2. DLC  layer

Various types of DLC can be used in the present invention. DLC with high thermal conductivity in terms of efficient heat diffusion is preferably used. As a method of generating the DLC, reference may be made to JP H10-072285, JP2002-115080, and US2005-0260411. However, other references may be referred to instead of or in addition to these references.

The DLC layer can be formed by a chemical vapor deposition (CVD) process. In a CVD process, precursor molecules in the gaseous phase can be dissociated, ie activated, by an energy source to form active species such as reactive radicals, ions, or atoms.

The CVD process may take place above atmospheric pressure (about 0.10 MPa (760 Torr)) with an energy source that may include a combustion flame source, such as an oxyacetylene torch source or a plasma torch source. The plasma torch source may comprise a direct current (DC) plasma arc jet source.

The CVD process may occur at atmospheric pressure (about 0.10 MPa (760 Torr)) or less with an energy source that may include a heat source, such as a hot filament (HF) source. The HF source may comprise a single filament or multiple filaments.

The CVD process may occur at atmospheric pressure (about 0.10 MPa (760 Torr)) or less with an energy source that may include an electron or ion bombardment source, such as an electrical discharge source or a plasma source.

The DLC layer can be formed by other methods. For example, the DLC layer may be formed by a physical vapor deposition (PVD) process. The conditions of the PVD are preferably determined based on the desired thickness and physical properties of the DLC layer.

3. electrical circuit

The electrical circuit may be formed of a conductive metal such as Ag, Cu, Al, or the like. Ag is the preferred conductive metal constituting the electrical circuit in terms of solder leach resistance. Electrical circuits can be formed in many ways. The manner of forming the electrical circuit is not limited in the present invention. Such methods include electroplating on preformed base conductive patterns, transfer of conductive tapes and application of thick film pastes. The thick film paste is cured or fired after the paste is applied. For example, thick film pastes are cured at temperatures below 300 ° C. Alternatively, the thick film paste is baked at a temperature above 300 ° C.

Commercially available thick film pastes can be used in the present invention. For example, such thick film pastes may be E. children. Available from E. I. du Pont de Nemours and Company.

Examples of electroplating include, for example, autocatalytic electroless plating and direct copper plating.

4. LED chip

The LED chip is mounted on the layer described above. There are several mounting patterns.

1 illustrates one embodiment of the present invention. The LED device of FIG. 1 includes a substrate 102, an anodized layer 104 formed on the surface of the substrate 102, a DLC layer 106 disposed on the anodized layer 104, a DLC layer 106. An electrical circuit 108 formed thereon, an LED chip 110 mounted on the anodized layer 104, and a wire bond 112 that electrically connects the LED chip 110 to the electrical circuit 108. do. In this embodiment, the LED chip 110 is mounted on the surface of the anodized layer 104. If no anodized layer 104 is formed, the LED chip is mounted on the surface of the substrate 102.

2 shows another embodiment of the present invention. In the LED device of FIG. 2, the LED chip 110 is mounted on the surface of the DLC layer 106.

When the LED chip 110 is mounted on the surface of the DLC layer 106, heat from the LED chip 110 can be efficiently diffused into the DLC layer 106 having a high thermal conductivity.

3 shows another embodiment of the present invention. In this embodiment, the LED chip 110 is flip-chip bonded and connected to the electrical circuit 108 without using wire bonds. Conductive adhesive or solder may be used to attach the LED chip 110 to the electrical circuit 108. Conductive adhesives include, but are not limited to, conductive pastes containing Ag particles, for example epoxy resins.

For the method of bonding the LED chip to the substrate, eutectic die-attach, polymer based adhesive or solder may be used.

The present invention will be described in more detail with reference to practical examples. However, the scope of the present invention is not limited to these actual examples anyway.

In order to examine the performance of the present invention, the following experiment was performed.

1. Electrically conductive circuit Solder  Leaching resistance

Solder leaching resistance is a basic characteristic usually required as far as the circuit is concerned. Experiments were conducted to confirm that the LED device of the present invention has a satisfactory solder leaching resistance. Specifically, four samples with satisfactory solder leaching resistance were compared with the samples of the present invention.

(Sample 1)

As a thick film paste, silver paste is screen-printed on the surface of a DLC sheet, and forms a predetermined electroconductive pattern. The paste was dried at 150 ° C. for 10 minutes and then cured at 200 ° C. for 30 minutes. The sample was then gold plated for wire bonding. The composition of the conductive pattern and the silver paste is shown in Table 1.

(Control Sample 2-5)

Four conventional samples (QS174, 5164N, 6179A, 6177T) were prepared by screen printing the thick film paste onto a reference alumina plate.

Sample 1 and Control Samples 2-5 were soaked in 63Sn / 37Pb liquid for 5 seconds. This dipping was repeated until solder leaching occurred.

To determine the solder leaching resistance, the electrical resistance of the serpentine shaped pattern was measured. The point of failure at which solder leaching occurred was identified at short circuit.

As shown in Table 2, the present invention exhibits better solder leaching resistance than conventional combinations.

2. Reliability Test

Samples in which a circuit is formed on a DLC coated substrate will be tested to verify the reliability of the circuit material. Reliability tests are expected to show superior performance compared to the prior art.

Typical reliability item is

(1) temperature conditions

(2) humidity conditions

(3) Includes corrosion test.

Samples of LEDs packaged on the claimed circuit / substrate will likewise be tested for reliability. Additional test items include

(1) life characteristics

(2) current conditions

(3) may include mechanical impact conditions.

3. Thermal management performance test

Samples are tested in a manner that compares the thermal management performance of LED devices with the thermal management performance of other commercially available substrates and packaging structures using the claimed structure.

The present invention shows good thermal management performance, including good thermal conduction properties, resulting in good quality (i.e., long life, emission efficiency, etc.) of a good device (LED device or end use) compared to other commercially available substrates and packaging structures. It is expected.

Claims (8)

A substrate comprising Cu and / or Al; A diamond-like carbon layer disposed on the substrate; An electrical circuit formed on the diamond-like carbon layer; And An LED device comprising an LED chip electrically connected to an electrical circuit. The LED device of claim 1, wherein the substrate is selected from the group consisting of a copper plate, an aluminum plate, a copper alloy plate, and an aluminum alloy plate. The LED device according to claim 2, wherein the substrate is an aluminum plate or an aluminum alloy plate, and the anodized layer is formed between the substrate and the diamond-like carbon layer. The LED device of claim 1, wherein the LED chip is wire bonded to an electrical circuit. The LED device of claim 1, wherein the LED chip is flip-chip bonded on the surface of the electrical circuit. The LED device of claim 1, wherein the LED chip is mounted on a diamond-like carbon layer. The back panel of the liquid crystal display device in which the LED device of Claim 1 is used as a light source. Providing a substrate comprising Cu and / or Al; Providing a diamond-like carbon layer disposed on the substrate; Forming an electrical circuit formed on the diamond-like carbon layer; And electrically connecting the LED chip to the electrical circuit.

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