KR101027422B1 - LED array board - Google Patents

Abstract

The present invention relates to an LED array substrate, a direct printing method using an aluminum base layer, an alumina insulating layer formed by anodizing on the aluminum base layer and a conductive paste composition comprising conductive particles and a heat resistant binder on the alumina insulating layer. It provides an LED array substrate consisting of an electrical circuit formed by.
The LED array substrate of the present invention forms a base layer and an insulating layer integrally to achieve a high heat dissipation structure to provide a high heat dissipation structure LED array substrate that can be used in the LED high density array substrate for high brightness. In addition, by directly printing with a conductive paste containing conductive particles and a heat resistant binder together with the basic structure of the substrate, an electrical circuit can be formed while increasing the insulation of the alumina insulating layer, thereby simplifying the manufacturing process and reducing the process cost and manufacturing time. Wastewater generation can be minimized.

Description

LED array board {a LED array board}

The present invention relates to an LED array substrate, particularly an LED array substrate having excellent heat dissipation effect and simple manufacturing process.

LEDs, that is, light emitting diodes (LEDs), are used in various fields such as display devices of electronic devices and light sources of large information display devices in various colors due to advantages of light efficiency and long life. Recently, it is gradually expanding its use in various lighting and LCD TV backlight fields.

In the case of LCD TV backlight, LED lighting, etc., an array is formed on a substrate using a plurality of light emitting elements for reasons of high luminance and flat light emission per unit area. It is well known that heat dissipation in LED packages is an important factor in maintaining quality such as LED life and efficiency. Especially when LEDs form an array, heat dissipation overlaps, so it is very important to effectively dissipate heat generated from the LEDs through the substrate.

Single-chip LED packages offer a variety of heat dissipation solutions based on the choice of structure or material for smooth heat dissipation. However, even if these single-chip LED packages are individually designed for heat dissipation, the intense surface lighting requires the integration of multiple light emitting elements on the board to form an array. Should be.

The LED array substrate mainly uses a metal core printed circuit board (MCPCB) including a metal substrate instead of a copper clad laminate (CCL) type PCB for smooth heat dissipation. Usually, the MCPCB has a three-layer structure of a metal base layer, an insulation layer, and a copper foil etching circuit. The insulating layer may use an epoxy or silicone resin filled with thermally conductive particles to increase thermal conductivity. LED substrate based on such MCPCB has a disadvantage that the heat dissipation performance is greatly limited because of the resin-based insulating layer. In addition, since the electric circuit formation of the MCPCB is manufactured using a lithography technique including resist pattern formation and etching, as in the conventional PCB, the manufacturing process is very complicated, and a large amount of etching wastewater is generated during the process.

Ceramic composite made of MCPCB or LTCC with metal layer + electric circuit formed on LED chip before packaging by applying COB (chip-on-board) technology, which attaches microchip or die directly to circuit board in semiconductor assembly process Techniques for mounting and packaging directly onto the board are being tried. However, the fabrication of LED array packages using COB technology involves complex and precise processes such as forming grooves to house LED chips, etching to form conductive layers and forming electrode circuits, forming reflectors, and encapsulating and forming lenses after chip mounting. This complexity and precision not only lowers the adaptability for various applications but also requires expensive process costs. For example, grooves, reflectors, and LED chip junction points, etc., must be precisely set according to the size and number of LED chips, and if any chip is mounted incorrectly, the entire package becomes defective. In addition, the heat radiation performance is still limited by the resin insulating layer of MCPCB, LTCC of considerable thickness, and the like.

The present invention is to provide a high heat dissipation structure LED array substrate that can be used in the LED high density array substrate.

In addition, the present invention is to provide an LED array substrate excellent in heat dissipation performance and excellent adaptability according to the use can be provided at low cost because the process is very simple because there is no need for copper foil lamination or metal deposition and no etching process.

According to the present invention, an aluminum base layer, the alumina insulating layer formed by anodizing on the aluminum base layer and the electric paste formed by a direct printing method with a conductive paste composition comprising conductive particles and a heat resistant binder on the alumina insulating layer An LED array substrate consisting of a circuit is provided. The LED array substrate may have an alumina layer formed by the same anodization on the back surface to prevent warpage by process or single side treatment. If desired , another electrical circuit can be formed under the back alumina layer in the same way as the electrical circuit on the front side. In the present invention, the term "electrical circuit" means an electrode circuit for supplying power to an LED or a signal circuit for control. The lower electric circuit may be used as a signal circuit or an electrode circuit for an LED mounted on the front surface, and in some cases, may be used as an electric circuit required to mount the LED to the rear side. In the case of such a double-sided circuit or double-sided mounting, energization between both sides is achieved by conventional via-hole technology.

If necessary, it is possible to the sealing process after the electric circuit before printing or printing in order to improve the breakdown voltage in the alumina insulating layer of the LED array substrate of the present invention. The LED array substrate may further have a plating layer by electroplating to improve conductivity and solderability according to the pattern on the electric circuit formed by the direct printing method. In addition, the LED array substrate may further have an electric circuit protective insulating layer covering the electric circuit except for the LED connection portion to protect the electric circuit. Such an electric circuit protective insulating layer is preferably laminated in the form of a pattern which exposes a contact with the LED by printing.

The aluminum base layer is made of aluminum or an aluminum alloy. The back surface portion of the aluminum base layer may be processed into a structure that enlarges a contact area with air, that is, a structure having a plurality of fins, and may be integrated with the heat sink. In addition, the aluminum base layer may be embedded or attached to a heat pipe or a thermoelectric element for cooling.

The alumina insulating layer is formed by anodizing (anodizing) the surface of the aluminum base layer, specifically, in a sulfuric acid, oxalic acid, phosphoric acid or chromic acid solution, particularly preferably in an oxalic acid solution to an aluminum substrate. Positive voltage is applied to promote oxidation to form a surface alumina layer of uniform thickness. If necessary, additives such as copper sulfate, lactic acid, citric acid, acetic acid, aluminum sulfate, and magnesium sulfate may be added to the oxalic acid solution. The alumina insulating layer may be formed in a pattern form or partially through a masking treatment on the aluminum plate. In order to use the back surface of the LED array substrate or to prevent warpage by single side anodization, the alumina insulating layer may be formed on the back surface with one anodization. This alumina layer is very hard, highly corrosion-resistant, and many pores with a diameter of about several tens of nm are formed. This pore causes the insulation of the oxide film to be degraded in general, and a sealing treatment is necessary. However, in the present invention, after the electric circuit is printed on the alumina insulating layer which is omitted or anodized, the sealing process can be performed as necessary. By printing an electrical circuit on the alumina insulating layer before the sealing treatment, the binder is bonded to the surface irregularities structure caused by the pores, thereby increasing the adhesion of the electrical circuit, and having the binder component of the paste serve as an auxiliary seal. The remaining pores are completed by the sealing treatment. This sealing process is completed by depositing an alumina insulating layer in the metal salt solution and then adding hot water.

The electrically conductive paste composition for forming an electric circuit preferably contains 0.01 to 96 parts by weight of conductive particles, 0.5 to 96 parts by weight of a heat resistant binder, and an organic solvent residual amount. Examples of the heat resistant binder used in the present invention include acrylics, urethanes, epoxys, and polyimides. In the present invention, the conductive particles are not particularly limited as particles of an electrically conductive material, and include carbon-based powders such as conductive metals, nonmetal powders, and graphite. The conductive particles are, for example, particles of gold, aluminum, copper, indium, antimony, magnesium, chromium, tin, nickel, silver, iron, titanium and alloys thereof. Examples of the carbon-based conductive particles include particles such as natural graphite, expanded graphite, graphene, carbon black, nanocarbon, and carbon nanotubes. As the form of the particles, for example, plate-like, fiber-like and nano-sized nanoparticle nanotubes can be used. These conductive particles may be used alone or in combination. Such conductive particles are preferably plate-shaped silver particles having a size of 0.1 to 10 µm.

Direct printing includes screen printing, flexographic printing, rotary printing, gravure printing, offset printing and printing methods such as inkjet. The conductive paste printed in the electric circuit pattern on the alumina insulating layer is cured by heating or light irradiation. The binder component of the conductive paste serves to fix the conductive particles to form a circuit and to fill the micropores formed in the alumina insulating layer to increase the insulation of the alumina insulating layer. In order to increase the conductivity of the electric circuit, a plating layer may be further formed on the electric circuit by applying voltage to the electric circuit pattern in the plating bath.

If necessary, in order to protect the electric circuit, an electric circuit protective insulating layer covering the electric circuit except for the LED connection part is laminated by printing in the form of a pattern excluding a contact with the LED using the thermosetting resin composition.

The LED array substrate of the present invention is mounted with LEDs in a semi-finished or finished state in which electrodes are exposed by various methods known in the electronic art, including soldering or SMT. For example, exposed electrical circuits are equipped with LED elements using solder cream and bonded in a reflow process. As needed prior to bonding, exposed electrical circuits include organic solder preserve (OSP), electro-less nickel immersion gold (ENIG), electro-less nickel electro-less palladium immersion gold (ENEPIG), etc. Surface treatment is possible .

The LED array substrate of the present invention forms a base layer and an insulating layer integrally to achieve a high heat dissipation structure to provide a high heat dissipation structure LED array substrate that can be used in the LED high density array substrate for high brightness. In addition, by directly printing with a conductive paste containing conductive particles and a heat resistant binder together with the basic structure of the substrate, an electrical circuit can be formed while increasing the insulation of the alumina insulating layer, thereby simplifying the manufacturing process and reducing the process cost and manufacturing time. Wastewater generation can be minimized.

1 is an interlayer conceptual perspective view of an LED array substrate of one embodiment of the present invention;
Figure 2 is a schematic assembly perspective view of the LED is mounted on the LED array substrate of Figure 1;

Hereinafter, the present invention will be described in detail with reference to Examples and drawings.

Example 1

A 305 X 255 X 1 mm sized aluminum sheet (1) was immersed in a SZ-9 degreasing agent of Jeyoungyoung Chemical consisting of NaOH, Na ₂ CO ₃ , NaHCO _{3 ,} surfactant and water for 15 minutes at 50-60 ℃. Degreasing After washing the degreased aluminum plate 1, it was immersed in a 10 g / L NaOH aqueous solution at 60 ℃ for 3 minutes and washed with water. The aluminum plate 1 was immersed in a 10% sulfuric acid solution at room temperature, the aluminum plate 1 was used as an anode, and energized for 60 minutes at a current density of 0.5 A / dm ² , respectively. ) Was formed.

650 g of plate-shaped silver powder with an average particle size of 1.97 μm, 240 g of a binder obtained by dissolving KER1009 epoxy from Kumho P & B Chemical in normal terpineol at 50% concentration, and the remaining amount of a solvent of butyl cellulose (trade name of 2-butoxyethanol) Silver paste was prepared by thoroughly mixing 1 Kg. The electrode circuit pattern 3 was printed on the alumina layer 2 of the aluminum plate using the silver paste using a flat screen printing machine. When the printed material was heat-treated at 190 ° C. for 12 minutes, the surface electric resistance of the electrode circuit was 8.6X10 ⁻⁵ Pa · cm, the adhesion was 5B, and the hardness was 5H.

The aluminum substrate on which the electrode was formed was immersed in an aqueous solution for 5 minutes with 2 g / L nickel acetic acid at room temperature, and then heated for 10 minutes in distilled water at 95 ° C. for sealing. The dielectric breakdown voltage of the treated aluminum substrate was 2.71 Kv / mm as measured using CHROMA AC / DC / IR HIPOT TESTER model 19052.

In order to form the protective insulating layer 5 on the substrate on which the electrode circuit was formed, screen printing was performed using a thermosetting solder resist SCR-1000W of Seoul Chemical Research Institute and heat-treated at 150 ° C. for 50 minutes. Solder cream was applied to the contacts 12 of the exposed electrode circuit of the aluminum substrate 10, the lead of the 1608 type LED 11 of Seoul Semiconductor was raised, and then the LED array was configured through a reflow process.

Example 2

A 305 X 255 X 1 mm sized aluminum sheet (1) was immersed in a SZ-9 degreasing agent of Jeyoungyoung Chemical consisting of NaOH, Na ₂ CO ₃ , NaHCO _{3 ,} surfactant and water for 15 minutes at 50-60 ℃. Degreasing After washing the degreased aluminum plate 1, it was immersed in a 10 g / L NaOH aqueous solution at 60 ℃ for 3 minutes and washed with water. At room temperature, the aluminum plate 1 is immersed in an aqueous solution in which 10 g / L boric acid, 3 g / L lactic acid, and 1 g / L magnesium sulfate are added to 50 g / L oxalic acid, and the aluminum plate 1 is used as an anode. 60 minutes at a density of 1.5 A / dm ² to form 33.6 and 32.5 μm thick alumina layers 2 and 6, respectively.

650 g of plate-shaped silver powder with an average particle size of 1.97 μm, 240 g of a binder obtained by dissolving KER1009 epoxy from Kumho P & B Chemical in normal terpineol at 50% concentration, and the remaining amount of a solvent of butyl cellulose (trade name of 2-butoxyethanol) 1 Kg consisting of completely mixed to prepare a silver paste. The electrode paste pattern 3 is printed on the alumina layer 2 of the aluminum plate 1 using the silver paste using a flat screen printing machine. When the printed material was heat-treated at 190 ° C. for 12 minutes, the electrical resistance of the electrode circuit was 8˜9 × 10 ⁻⁵ Pa · cm, the adhesion strength was 5B, and the hardness was 5H.

The aluminum substrate on which the electrode was formed was immersed in an aqueous solution of 5 g / L nickel fluoride for 20 minutes at room temperature, and then heated for 20 minutes in an aqueous nickel acetic acid solution at 90 ° C. The dielectric breakdown voltage of the manufactured aluminum substrate was 2.66 Kv / mm as measured using CHROMA AC / DC / IR HIPOT TESTER model 19052. The thermal conductivity of the substrate was measured using a TPA-501 model of HOT Disk AB, which was determined to be 56.49 W / m · K. Considering that the thermal conductivity of the general MCPCB is about 2.0 W / m · K or less, it was confirmed that the thermal conductivity of the substrate was excellent.

220 g of copper sulfate, 63 g of sulfuric acid, 10 ppm of chlorine, 10 g of IBC 5007-MU, an antirust additive, 5000-A 0.5 g, 5007-B 0.5 g, and 1 L of water were immersed in the aluminum substrate 35 Electrolytic plating was performed for 30 minutes on the printed electrode circuit which was energized at a current density of 5 A / dm ² under the conditions of 占 폚 or less to obtain a plating layer 4 having a plating thickness of 3 µm and a surface resistance value of 5X10 ^-6 Pa.cm.

In order to form the protective insulating layer 5 on the substrate on which the electrode circuit was formed, screen printing was performed using a thermosetting solder resist SCR-1000W of Seoul Chemical Research Institute and heat-treated at 150 ° C. for 50 minutes. Solder cream was applied to the contacts 12 of the exposed electrode circuit of the completed LED array aluminum substrate 10, the lead of the 1608 type LED 11 of Seoul Semiconductor was raised, and then the LED array was constructed through a reflow process. As a result of measuring the adhesion strength of the attached LED, it showed 2.67 Kg _f .

Reference Signs List 1: aluminum plate 2: alumina layer 3: electrode circuit pattern
4 plating layer 5 protective insulating layer 6 backside alumina layer
10 LED array substrate 11 LED 12 contact

Claims (12)

delete delete An electrical circuit formed by a direct printing method with an aluminum base layer, an alumina insulating layer formed by anodizing on the aluminum base layer, and a conductive paste composition comprising conductive particles and a heat resistant binder on the alumina insulating layer; Alumina Insulation Layer LED array boards sealed with metal salts after electrical circuit printing delete delete The LED array substrate of claim 3, wherein the alumina insulating layer is formed partially or in a pattern on the aluminum base layer. The LED array substrate of claim 3, wherein the LED array substrate further includes a plating layer formed by plating according to a pattern on an electric circuit formed by a direct printing method. The LED array substrate of claim 3, wherein the LED array substrate further includes an electrical circuit protection insulating layer covering the electrical circuit except for a contact with the LED. The LED array substrate of claim 8, wherein the contact is surface-treated with an organic solder preserve (OSP), an electro-less nickel immersion gold (ENIG), or an electro-less nickel electro-less palladium immersion gold (ENEPIG). The LED array substrate of claim 3, wherein a back side of the aluminum base layer has a plurality of pins. The alumina insulating layer is obtained by anodizing the aluminum base layer by adding an additive selected from the group consisting of copper sulfate, lactic acid, citric acid, acetic acid, aluminum sulfate, magnesium sulfate and mixtures thereof in an oxalic acid solution. LED Array Board The LED array substrate of claim 3, wherein the conductive particles are plate-shaped silver particles having a size of 0.1 to 10 μm.

Images