KR20020018798A - Method for Manufacturing Micro Tip Array and Field Emission Display Device - Google Patents

Abstract

PURPOSE: A method for manufacturing a micro-tip array and an FED(field emission display device) is provided to enhance luminescence of the FED by uniformly forming more nano tube over a unit area. CONSTITUTION: Ag paste is printed over a bottom glass(10) by a screen printing and sintered at 580°C to form a cathode metal electrode(12). Instead of Ag paste, Al, Au, Cu, or Pt can be used. The bottom glass(10) is plated by using Ni, Fe or Cobalt as a seed metal(14), over the cathode metal electrode(12). The plated bottom glass(10) is inserted into a CVD(chemical vapor deposition) reactor at 500-580°C where the seed metal(14) is etched to grow carbon nano tube(16) on the surface of the seed metal. The bottom glass(10) is sealed with a top glass(20) having an anode electrode and a luminescent layer(24). Inner air is exhausted from inside between the sealed top and bottom glasses to make vacuum state.

Description

Method of manufacturing micro tip array and method of manufacturing field emission display device {Method for Manufacturing Micro Tip Array and Field Emission Display Device}

The present invention relates to a method of manufacturing a micro tip array and a method of manufacturing a field emission display device (hereinafter referred to as FED), in particular, after seed metal is plated on the surface of a thick film electrode, The present invention relates to a method for forming a micro tip array uniformly distributed and improving density by growing carbon nanotubes by low temperature CVD.

FED uses an array of numerous tip and small electron emitters, a micro tip array, arranged on one plate. When a voltage is applied between the cathode and the gate electrode on which the electron emitter is formed, electrons are emitted from the electron emitter. The emitted electrons are accelerated by the high voltage applied between the cathode and the anode and collide with the phosphor formed on the anode to generate light. At this time, the brightness or color can be adjusted by changing the density of the emitted electrons reaching the respective fluorescent layers by the voltage applied to the gate electrode.

The amount of electrons emitted from the electron emitter is influenced by the strength of the applied electric field and the material and shape of the electron emitter. Since the voltage applied to the electrode is in the tendency to lower the voltage from several hundred V to several tens V, the technology development regarding the material and shape of the electron emitter is required as the lower voltage is increased.

Accordingly, as a result of finding and observing carbon nanotubes that can withstand a strong electron beam and can be easily manufactured in a sharp shape and arranged in an accurate pattern, it is confirmed that electrons are emitted from the ends of the carbon nanotubes. The application as an emitter was sought.

In order to grow carbon nanotubes, arc discharge, laser evaporation, and chemical vapor deposition are used, but the process temperature is high, so that they cannot be grown directly on a glass substrate. Therefore, there is also a method of mixing the carbon nanotubes made by the arc discharge or laser evaporation method with silver paste and printing, but the uniformity of the tip density is poor, the quality of the final product is inferior.

An object of the present invention is to uniformly form more nanotubes per unit area by coating a thick-film metal electrode with seed metal and growing nanotubes on the coated seed metal by low temperature CVD in order to solve the problems of the prior art. The present invention provides a method of manufacturing a micro-tip array capable of improving the latitude of an FED and a method of manufacturing a field emission display device using the same.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the configuration of a signal emitting display device having a micro tip array according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: lower glass substrate 12: cathode metal electrode

14 nickel seed layer 16 carbon nanotube

20: upper glass substrate 22: anode wood electrode

24: phosphor layer

In order to achieve the above object, the manufacturing method of the present invention comprises the steps of forming a thick film electrode by printing a metal paste on a glass substrate, coating the surface of the thick film electrode with a seed metal, and a low temperature on the seed metal surface Growing carbon nanotubes by chemical vapor deposition;

In the low temperature chemical vapor deposition method, it is preferable to grow carbon nanotubes in an ammonia and acetylene gas atmosphere while maintaining the internal temperature of the CVD reactor at 580 ° C. or lower. The metal paste may use any one of silver (Ag), aluminum (Al), gold (Au), copper (Cu), and platinum (Pt). The seed metal uses any one of transition metals such as nickel (Ni), iron (Fe), and cobalt (Co). The seed metal coating is preferably coated at about 2,000 kPa or less by the electroplating method.

The field emission display device of the present invention comprises the steps of printing a metal paste on a lower glass substrate to form a thick film metal cathode, coating a seed metal on the surface of the cathode, and a low temperature chemical vapor phase on the seed metal surface Growing a plurality of upright carbon nanotubes by immersion to form a micro tip array, forming an anode on an upper glass substrate, forming a phosphor layer on the surface of the anode, and And evacuating and then encapsulating the air between the substrates such that the micro tip array of the substrate and the anodes of the upper glass substrate face each other at a predetermined interval.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail.

1 shows a cross-sectional structure of a field emission display device according to the present invention. First, the SODA-LIME glass substrate is cut, chamfered, and washed to prepare the field emission display device, thereby preparing an insulating lower glass substrate 10 and an upper glass substrate 20, respectively.

Subsequently, a silver paste (Ag3350 manufactured by Ferro Co., Ltd. or Daeju Fine Chemicals Ag-7068 manufactured by US Ferro Co., Ltd.) commercialized to form the cathode metal electrode 12 on the lower glass substrate 10 was printed by screen printing, and then 580 Calcining at &lt; RTI ID = 0.0 &gt; Since the surface of the fired cathode metal electrode 12 is a thick film formed by the screen printing method, the density is less than that of the thin film metal formed by the sputtering method or the evaporation method. Since more carbon nanotubes can be formed, the tip density per unit area is high, so the electron emission per unit area is high.

In addition, since the thin film metal does not endure the frit sealing process that must be passed during the manufacture of the field emission display device, the thin film metal must be accompanied by a process of reinforcing the lower electrode with a metal paste. However, if the lower electrode is formed through one printing process as described above, it is advantageous in many ways than using a metal thin film as the lower electrode. First, the photolithography process, which must be performed to form the lower electrode in the thin film process, can be omitted, so that the process can be simplified and the process cost can be reduced.

In addition, since the lower electrode manufactured by the thin film process is dense, strong etching is required to make nano-sized seeds necessary for growing carbon nanotubes. In general, ammonia etching is usually performed after hydrofluoric acid etching. In the case of using the lower electrode as a thick film, since the thick film itself is uneven and there are many defects in the seed layer coated thereon, it is easily etched, so that dangerous hydrofluoric acid etching can be omitted and nano-sized seeds can be made only by ammonia etching.

In addition, when a thick film is used, the substrate and the adhesive force of the carbon nanotubes are superior to the thin film. Indeed, when a field effect display device is made of carbon nanotubes deposited using a thin film lower electrode, and driven by applying an electric field, the adhesion to the substrate is weak, resulting in a problem of falling carbon nanotubes. When the lower film is used as the lower electrode, the carbon nanotubes grown from the space between the metal particles in the thick film are strongly attached to the substrate, and thus there is no dropout of the carbon nanotubes due to the lack of adhesion.

In addition, aluminum (Al), gold (Au), copper (Cu), platinum (Pt), or the like may be used instead of the silver paste.

Next, a nickel electroplating bath is prepared. The electrolytic plating bath is prepared by dissolving 150 g of nickel sulfate (NiSO 4-6 H 2 O), 15 g of ammonium chloride (NH 4 Cl), and 15 g of boronic acid (H 3 BO 3) in 1 L of water. The lower glass substrate 10 having the cathode metal electrode 12 formed in the prepared electrolytic plating bath was connected, and a DC power supply was connected thereto to flow 10-200 mA / cm 2 to plate a thickness of about 2,000 kPa or less. The seed metal may be a transition metal such as iron or cobalt in addition to nickel.

Insert the lower glass substrate plated with nickel, which is the seed metal 14 on the surface of the metal electrode 12, into the CVD reactor and keep the process temperature at 500 to 580 ° C. while flowing ammonia (NH 3) first to seed the seed metal. After etching with particles, carbon nanotubes 16 are grown by flowing acetylene (C2H2). The grown nanotubes form a micro tip array.

Therefore, the carbon nanotubes are grown on the seed metal 14 coated on the thick film metal electrode 12 having a large surface area, and thus, when the carbon nanotubes previously grown by the arc discharge method are simply mixed with silver paste for screen printing. In comparison, more carbon nanotubes 16 are grown per unit area, and uniformity is also excellent.

An anode electrode 22, which is a transparent electrode, is formed on the upper glass substrate 20 using ITO. After forming the anode electrode, the phosphor layer 24 is formed to complete the upper substrate.

The completed lower substrate and the upper substrate are positioned to face each other at a predetermined interval to seal each other, and the internal air is exhausted and sealed to make a vacuum to complete the field emission display device.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will 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 below I can understand that you can.

As described above, in the present invention, more carbon nanotubes per unit area can be formed by forming a cathode metal electrode into a thick film by screen printing, coating a seed metal thereon, and growing carbon nanotubes by low temperature CVD. Therefore, since the tip density per unit area is high and the tip density is high, the amount of electron emission per unit area can be expected to improve the brightness.

In addition, since the adhesion of carbon nanotubes is better than that of using a thin film lower electrode, the line pattern can be formed by one-time screen printing, which is a low-cost process, so that the photolithography process can be omitted and the process can be simplified. The cost of processing can also be lowered.

Claims (9)

Printing a metal paste on a glass substrate to form a thick film electrode; Coating a surface of the thick film electrode with a seed metal; And And growing carbon nanotubes on the seed metal surface by a low temperature chemical vapor deposition method. The method of claim 1, wherein the low temperature chemical vapor deposition method grows carbon nanotubes in an ammonia and acetylene gas atmosphere while maintaining the internal temperature of the CVD reactor at 580 ° C. or less. The method of claim 1, wherein the metal paste is any one of silver (Ag), aluminum (Al), gold (Au), copper (Cu), and platinum (Pt). The method of claim 1, wherein the seed metal is any one of transition metals such as nickel (Ni), iron (Fe), and cobalt (Co). The method of claim 1, wherein the seed metal is coated by electroplating. The method of claim 1, wherein the seed metal has a coating thickness of 2,000 kPa or less. Printing a metal paste on the lower glass substrate to form a thick film metal cathode; Coating a seed metal on the surface of the cathode; Growing a plurality of upright carbon nanotubes on the seed metal surface by low temperature chemical vapor deposition to form a micro tip array; Forming an anode on the upper glass substrate; Forming a phosphor layer on the surface of the anode; And vacuum encapsulating air between the substrates so that the micro tip array of the lower glass substrate and the anodes of the upper glass substrate face each other at a predetermined interval, and then encapsulating the air between the substrates. . 8. The method of claim 7, wherein the low temperature chemical vapor deposition method grows carbon nanotubes in ammonia and acetylene gas atmospheres while maintaining the internal temperature of the CVD reactor at 580 degrees or less. The method of manufacturing a field emission display device according to claim 7, wherein the seed metal coating of the cathode is plated with nickel (Ni) at 2000 kPa or less by electroplating.