KR101232798B1 - A producing method for electrode of electric material - Google Patents

Abstract

The present invention relates to a method for forming an electrode for an electronic material, the method for forming an electrode for an electronic material according to the present invention has a high coating film adhesion strength with the substrate, it is possible to obtain excellent electrical resistivity characteristics even in a low temperature region of less than 300 ℃, in particular When applied to a solar cell, the weldability with the solder ribbon is very excellent, and the printing property is excellent, so that a high resolution electrode pattern can be realized, and the rheology characteristic is excellent, thereby achieving a high aspect ratio.

Conductive, Paste, Ink, Solar Cell, Electrode, Water Glass

Description

Electrode Formation Method for Electronic Materials {A PRODUCING METHOD FOR ELECTRODE OF ELECTRIC MATERIAL}

The present invention relates to a method for forming an electrode for an electronic material, and more particularly, has a high coating film adhesion strength with a substrate, and excellent electrical resistivity characteristics can be obtained even in a low temperature region of 300 ° C. or lower, and when applied to a solar cell, The present invention relates to a method of forming an electrode for an electronic material, which has excellent weldability, excellent printing characteristics, and can realize a high-resolution electrode pattern, and further, excellent rheological characteristics, thereby achieving a high aspect ratio.

Conventional electronic devices, for example, solar cells, display devices, low-temperature electrode technology applied to products such as RFID devices (RFID), conductive powder, thermosetting resins (epoxy, silicon, etc.), curing agents, solvents, etc. Techniques for mixing pastes have been used. However, such a conductive paste is a chemical bonding method for securing a bonding force with a substrate by a compound produced by curing upon heating, and has a disadvantage in that the coating film strength is weak, and the adhesion between the conductive powders is reduced, thereby making it difficult to obtain excellent electrical conductivity. For example, in the case of solar cells, the weldability of the electrode and the solder ribbon is required, but the epoxy cured product causes a problem that the solder hardenability is deteriorated due to the thermal deformation of the resin already cured due to the temperature (150-450 ° C.) applied during welding. .

Therefore, the object of the present invention is high coating film adhesion strength with the substrate, it is possible to obtain excellent electrical resistivity characteristics even in the low temperature region below 300 ℃, when applied to the solar cell is very excellent weldability with the solder ribbon, excellent printing characteristics By providing a high-resolution electrode pattern, it is further to provide an electrode forming method for an electronic material that can implement a high aspect ratio by excellent rheological properties.

In order to achieve the above object,

a) one kind from the group consisting of silver powder, gold powder, platinum powder, palladium powder, indium powder, copper powder, nickel powder, nickel powder coated with silver, copper powder coated with silver, and tin powder coated with silver 30 to 95 wt% of the conductive powder selected above; b) 0.1 to 20% by weight of water glass; c) 0.5 to 50% by weight of a binder selected from the group consisting of cellulose resins, acrylic resins or copolymers thereof, alkyd resins, butyral resins and polyvinyl alcohols; And d) printing a conductive electrode forming composition for forming an electrode comprising a residual amount of a solvent having a boiling point of 80-300 ° C. on a substrate, and calcining at 100-300 ° C. for 5 to 60 minutes. An electrode forming method for an electronic material is provided.

In addition, the present invention provides an electrode for an electronic material formed by the electrode forming method, and a solar cell, a display element, and an RFID element including the electrode.

According to the present invention, the coating film adhesion strength with the substrate is high, excellent electrical resistivity characteristics can be obtained even in a low temperature region of 300 ° C. or less, and when applied to a solar cell, the weldability with the solder ribbon is very excellent and the printing characteristics are excellent. It is possible to implement a high-resolution electrode pattern, and furthermore, it is possible to realize a high aspect ratio due to the excellent rheology of the paste.

The composition for forming a conductive electrode used in the present invention is a conductive metal powder; water glass; bookbinder; And a solvent.

In the present invention, the "composition for forming an electrode" includes a composition used as a circuit forming material such as an electronic device made of a laminated structure or a wiring board made of a single layer or a multilayer. Therefore, not only the electrodes used for solar cells, display elements, RFID elements, etc. but also the electric wirings used for these apparatuses are applicable.

The composition for forming a conductive electrode of the present invention may be prepared in paste or ink form. The properties of the composition can be obtained by adjusting the weight ratio of the kind of conductive powder used and the organic matter (binder, solvent).

The conductive powder in the composition for forming a conductive electrode of the present invention includes silver powder, gold powder, platinum powder, palladium powder, indium powder, copper powder, nickel powder, nickel powder coated with silver, copper powder coated with silver, and silver Conductive powder selected from the group consisting of coated tin powder can be used. Preferably, silver powder having a low specific resistance or metal powder coated with silver may be used.

These shapes may be spherical, plate-like, needle-like, indefinite, or the like, and the average particle diameter of the particles is preferably 0.01 to 30 m. If the average particle diameter is smaller than 0.01 μm, the powders are agglomerated with each other and high dispersion is difficult, and the paste may be difficult to form due to high viscosity. If the average particle diameter exceeds 30 μm, there may be a problem that it is difficult to form a fine pattern when the conductor pattern is formed. Can be.

Such conductive powder may be included in the solid content of 30 to 95% by weight, and when added to less than 30% by weight, the contact density of the conductive powder is small, the pattern height is low when the fine pattern is implemented, the line resistance characteristics are insufficient, and the viscosity of the paste Low patterns may cause spreading of the pattern. In addition, when the content exceeds 95% by weight, it is difficult to uniformly disperse the conductive powder and the coating property may be reduced, thereby forming a conductor having a non-uniform pattern.

Water glass used as the inorganic adhesive includes a material represented by the following formula.

M ₂ O-nSiO ₂ -H ₂ O (M is an alkali metal, n is a number from 1-8)

The water glass is an alkali silicate salt obtained by melting silicon dioxide and an alkali or an aqueous solution thereof, and examples of more specific materials include SiO ₂ K ₂ O, SiO ₂ Li ₂ O, SiO ₂ Na ₂ O, and the like. It can be illustrated. The content of the water glass is not particularly limited as long as it is an amount capable of achieving the object of the present invention, and is 0.1 to 20% by weight, preferably 1.0 to 10% by weight, depending on the weight of the conductive paste. If the content of the water glass is less than 0.1% by weight, there is a fear that the adhesive strength is insufficient, if the content of the water glass exceeds 20% by weight it is difficult to expect excellent electrical properties.

As the binder used in the composition for forming a conductive electrode of the present invention, those known in the art may be used. For example, a binder selected from the group consisting of cellulose resins, acrylic resins or copolymers thereof, alkyd resins, butyral resins and polyvinyl alcohols can be used. Specifically, cellulose-based resins such as methyl cellulose, ethyl cellulose, nitro cellulose, hydroxy cellulose, hydroxypropyl cellulose; Acrylic resins such as methyl methacrylate, n-butyl methacrylate, ethyl methacrylate, isobutyl methacrylate or copolymers thereof, alkyd resin, saturated polyester resin, butyral resin, polyvinyl alcohol, etc. Can be mentioned. A binder can be used individually or in mixture of 2 or more. The content of the binder is 0.5 to 50% by weight, preferably 1 to 30% by weight, based on the weight of the conductive composition.

The solvent that can be used in the present invention is not particularly limited, and the boiling point is preferably 80 ° C. or higher, more preferably 150 ° C. or higher. The boiling point here is a boiling point in normal pressure. By using the thing whose boiling point is 80 degreeC or more as a solvent, it can prevent that the drying speed of a composition becomes excessively fast. This is advantageous in that a problem can be prevented from forming in the coating film of the composition, and furthermore, a conductive thin film having desired characteristics can be obtained. Although there is no restriction | limiting in particular in the upper limit of the boiling point of a solvent, When considering the drying rate of a coating film, Preferably it is 300 degrees C or less.

As a solvent, both an aqueous and non-aqueous are used. For example, water, polyhydric alcohol, polyhydric alcohol alkyl ether, polyhydric alcohol aryl ether, ester, nitrogen-containing heterocyclic compound, amide, amine, long chain alkanes, cyclic alkanes, aromatic hydrocarbons, monoalcohols and the like can be used. These solvents can be used individually or in combination of 2 or more types.

As the polyhydric alcohol, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, dipropylene glycol, triethylene glycol and the like can be used.

As a polyhydric alcohol alkyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, dietylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol mono Methyl ether, triethylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol methyl ether, dipropylene glycol methyl ether, etc. can be used.

Ethylene glycol monophenyl ether etc. can be used as polyhydric alcohol aryl ether.

As acetate, ethyl cellosolve acetate, butyl cellosolve acetate, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, (gamma)-butyrolactone, etc. can be used.

As the nitrogen-containing heterocyclic compound, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like can be used.

As the amide, formamide, N-methylformamide, N, N-dimethylformamide, or the like can be used.

As the amine, monoethanolamine, diethanolamine, triethanolamine, tripropylamine, tributylamine and the like can be used.

As the long chain alkanes, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane and the like can be used.

Cyclohexane, decalin, etc. can be used as cyclic alkane.

Benzene, toluene, xylene, dodecylbenzene, trimethylbenzene, etc. can be used as an aromatic hydrocarbon.

Monoalcohols include propanol, butanol, pentanol, hexanol, heptanol, octanol, decanol, cyclohexanol, terpineol, benzyl alcohol, 2-propanol, sec-butanol, t-butanol, 2-pentanol, 3-pentanol, 2-ethyl-1-butanol, 2-heptanol, 3-heptanol, 2-octanol, 3-octanol, 4-octanol, 2-ethylhexanol, nonanol and the like can be used. have.

In addition, the composition for forming a conductive electrode of the present invention may further include additives that may be conventionally included as needed. Examples of the additives include thickeners, stabilizers, dispersants, surfactants, plasticizers, leveling agents, leveling agents, antifoaming agents, and the like in the range of 0.1 to 5% by weight based on the weight of the electrode composition of the present invention. It is good to use.

In addition, an organic solvent may be further blended to adjust the appropriate viscosity of the composition for forming a conductive electrode of the present invention. Examples of the organic solvent include aromatic hydrocarbons such as toluene, xylene, mesityrene and tetramine; Ethers such as tetrahydrofuran; Ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and isoboron; Lactams such as 2-pyrrolidone, 1-methyl-2-pyrrolidone; Ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, or propylene glycol derivatives corresponding thereto Alcohols; Esters such as acetic acid esters corresponding thereto; And diesters such as methyl esters of dicarboxylic acids such as malonic acid and succinic acid and ethyl esters. The amount of the organic solvent to be used may be appropriately selected depending on the type and content of the conductive particles used, the printing of the conductive composition, or the method of coating.

When preparing the composition for forming a conductive electrode of the present invention as a paste may be obtained by blending the above-mentioned essential components and optional components in a predetermined ratio and uniformly dispersed in a kneader such as a blender or a triaxial roll. . Preferably, the conductive paste of the present invention has a Brookfield HBT viscometer at 1 to 300 Pa when measured at a shear rate of 3.84 sec ⁻¹ at 25 ° C. as a # 51 spindle ^. It may have a viscosity of S.

When preparing the composition for conductive electrode formation of this invention with ink, the conductive ink of this invention can set the viscosity extensively. Specifically, the viscosity of the conductive ink of the present invention is preferably 100 mPa · s or less, particularly 50 mPa · s or less at 20 ° C. What is necessary is just to adjust the compounding quantity of the above-mentioned each component mix | blended with the viscosity of ink suitably. In this case, the viscosity can be measured by a vibratory viscometer (VM-100A manufactured by Yamaichi Denki Co., Ltd.) or a viscoelasticity measuring device (RS-1 manufactured by Hake Corporation).

In particular, when the conductive ink of the present invention is applied to an inkjet printing method as described below, the viscosity (20 ° C) is preferably set to 0.1-50 mPa · s, particularly 0.1-30 mPa · s.

The conductive ink composition of the present invention is prepared, for example, by the method described below. The conductive metal powder is dispersed in a solvent to obtain a slurry. Water glass as an inorganic adhesive is added to the slurry thus obtained, followed by stirring and mixing. In this way, the target ink is obtained.

When preparing the composition for forming a conductive electrode according to the present invention in the form of a paste, the compounding component is printed or coated on the metal layer formed by sputtering, spraying, sintering, etc. by any method such as screen printing, transfer, immersion coating, etc. It can be used to form electrodes used in various electronic components (solar cell, display, RFID device, etc.) by heating by curing at 200 ° C. for 10 to 30 minutes.

The present invention includes the step of printing the conductive paste or ink on a substrate, and baking for 5 to 60 minutes at 100-300 ℃ to form an electrode for electronic materials. Optionally, it may further comprise a drying step before the firing step. Except for using the conductive paste or ink in the method for forming an electrode for an electronic material of the present invention, the substrate, printing, drying or firing (except for temperature) may be generally used methods for producing an electrode of an electronic material. Of course. For example, the substrate may be a Si substrate, the electrode may be a front electrode of a silicon solar cell, the printing may be screen printing, the drying is for 3 to 30 minutes at 60-150 ℃, and the firing is It can be carried out at 150-300 ° C for 5 to 60 minutes. In addition, drying and firing are performed at the same time at a low temperature of 100-300 ℃. It may be performed for 5 to 60 minutes. The printing is preferably printed in a thickness of 15 to 50 ㎛. As a specific example, in the structure of the solar cell described in Japanese Patent Laid-Open No. 2005-268239 and its production, the electrode of the solar cell can be formed using the paste for forming a solar cell electrode of the present invention.

The electrode formation method for electronic materials of this invention is used suitably as an electronic device which consists of a laminated structure, and the circuit formation material, such as the wiring board which consists of a single | mono layer or a multilayer. It is particularly suitable for solar cells, display devices and RFID devices. Specifically, the conductive paste is printed on a substrate made of various materials such as glass, ceramics, metal, plastic, etc. according to the electrode forming method of the present invention using a known printing method with a predetermined printing pattern. Subsequently, when the formed printing pattern is fired in the atmosphere, in an inert atmosphere or in vacuum, a target conductive thin film is formed.

The electrode obtained from the electrode forming method according to the present invention has a high coating film adhesion strength with the substrate, excellent electrical resistivity characteristics can be obtained even in a low temperature region of less than 300 ℃, and when applied to a solar cell, the weldability with the solder ribbon is very excellent. In addition, it is possible to implement a high-resolution electrode pattern with excellent printing characteristics. In addition, the rheological properties of the paste are excellent, resulting in high aspect ratios.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

[Example]

Example 1

35% by weight of a spherical silver powder with an average particle diameter of 0.1 μm, 1% by weight of potassium silicate, 11% by weight of hydroxycellulose as a binder, 12% by weight of isobutyl methacrylate, 30% by weight of ethylene glycol as a solvent, and 10 parts of butyl cellulsolve The conductive paste was prepared by mixing and dispersing the wt% and 1 wt% of the dispersant with a three roll kneader.

Example 2

In Example 1 70% by weight of the spherical silver powder having an average particle diameter of 2.5 ㎛, 3% by weight of potassium silicate, 3% by weight of hydroxycellulose as a binder, 3% by weight of isobutyl methacrylate, 15% by weight of ethylene glycol as a solvent A conductive paste was prepared in the same manner as in Example 1, except that 5 wt% of butyl cellussolve and 1 wt% of a dispersant were used.

Example 3

In Example 1, 82 wt% of the spherical silver powder having an average particle diameter of 2.5 μm, 3 wt% of potassium silicate, 2 wt% of hydroxycellulose as a binder, 0.5 wt% of isobutyl methacrylate, and 8 wt% of ethylene glycol as a solvent A conductive paste was prepared in the same manner as in Example 1, except that 4 wt% of butyl cellussolve and 0.5 wt% of a dispersant were used.

Example 4

A conductive paste was prepared in the same manner as in Example 1, except that 3 wt% of sodium silicate was used as the water glass in Example 3.

Example 5

A conductive paste was prepared in the same manner as in Example 1, except that 3% by weight of lithium silicate was used as the water glass in Example 3.

Example 6

A conductive paste was prepared in the same manner as in Example 1, except that 82 wt% of silver coated copper powder was used as the conductive powder in Example 3.

Comparative Example 1

In Example 1 70% by weight of the spherical silver powder having an average particle diameter of 2.5 ㎛, 10% by weight of bisphenol A resin as epoxy resin, 1% by weight of amine-based curing agent, 13% by weight of ethylene glycol as solvent, 5% by weight of butyl cellsolve Conductive paste was prepared in the same manner as in Example 1, except that%, and 1 wt% of a dispersant were used.

Comparative Example 2

In Example 1, 85 wt% of the spherical silver powder having an average particle diameter of 2.5 μm, 5 wt% of a bisphenol A resin as an epoxy resin, 0.5 wt% of an amine curing agent, 5 wt% of ethylene glycol as a solvent, and 4 wt% of butylcellulose solution Conductive paste was prepared in the same manner as in Example 1, except that%, and 0.5 wt% of a dispersant were used.

[Experimental Example]

Specific resistance, coating film strength, substrate adhesion, welding strength, resolution, and aspect ratio of the conductive pastes prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were measured, as shown in Table 1 below.

The resistivity was calculated by printing the electrode paste on an alumina substrate, firing at 250 ° C. for 30 minutes, measuring the sheet resistance using a 4 point probe, and measuring the height using a scanning electron microscope (SEM). The coating film strength was measured for the scratch hardness using a pencil lead of 4B ~ 4H on the fired specimen. The evaluation of substrate adhesion was performed by lattice adhesion evaluation (ASTM D3359), and the number of grids torn after the adhesion evaluation was recorded using 3M tape # 610 for 100 lattice. The welding strength was measured by tearing strength of the electrode and the solder ribbon by using an adhesion tester (SESIN Corporation SS30WD). In the resolution evaluation, a resolution mask having a line width of 60-120 μm was recorded at a resolution of 10% or less of the line width change rate of the pattern after printing, drying, and firing. The aspect ratio is expressed as the ratio of height / line width × 100 of the pattern.

[Table 1]

As can be seen in Table 1, the substrate adhesion is excellent, and even when the substrate material is metal, ceramic, or glass, the adhesion strength is excellent, and thus it can be widely used in electronic devices such as solar cells, displays including PDP, and RFID. In addition, the electrode forming method according to the present invention has excellent electrical resistivity characteristics even in the low temperature region (below 300 ℃) in the low temperature process and low temperature such as heterojunction solar cell (HIT Cell), thin film solar cell, polymer solar cell It is applicable to the field where an electrode is required. In addition, the electrode forming method according to the present invention has a high pull adhesive strength of 200 gf or more after solder ribbon welding, excellent welding strength, excellent rheological properties of the paste is easy to implement a high-resolution pattern of 80 ㎛ or less. In addition, the electrode forming method according to the present invention has a higher aspect ratio than the conventional paste, so that the screen mesh is eliminated during printing, and thus a high aspect ratio pattern can be realized, thereby obtaining excellent line resistance characteristics even at high resolution.

Claims (9)

a) one kind from the group consisting of silver powder, gold powder, platinum powder, palladium powder, indium powder, copper powder, nickel powder, nickel powder coated with silver, copper powder coated with silver, and tin powder coated with silver 30 to 95 wt% of the conductive powder selected above; b) 0.1 to 20% by weight of water glass; c) 0.5 to 50% by weight of a binder selected from the group consisting of cellulose resins, acrylic resins or copolymers thereof, alkyd resins, butyral resins and polyvinyl alcohols; And d) printing an electrode-forming conductive composition comprising a residual amount of a solvent having a boiling point of 80-300 ° C. on a substrate, and baking at 100-300 ° C. for 5 to 60 minutes. Formation method for electrodes. The method of claim 1, The water glass is one or more from the group consisting of potassium silicate, sodium silicate and lithium silicate Electrode forming method for an electronic material, characterized in that the water glass containing a material selected. The method of claim 1, The water glass is an electrode forming method for an electronic material, characterized in that selected from the material represented by the following formula: M ₂ O-nSiO ₂ -H ₂ O (M is an alkali metal, n is a number from 1-8) The method of claim 1, The conductive composition for forming an electrode has a viscosity of 1 to 300 Pa ^. It is a paste which is S, The electrode formation method for electronic materials characterized by the above-mentioned. The method of claim 1, And said conductive composition for forming an electrode is an ink having a viscosity of 0.1-50 mPa · s. delete delete delete delete