KR101232475B1 - Glass frit for photosensitive conductive paste - Google Patents

Abstract

Glass frit for photosensitive conductive paste, having a softening point of 480 to 540 ° C., having a refractive index in the range of 1.5 to 1.7, and containing 5 to 50% by mass in a photosensitive conductive paste containing conductive powder and a photosensitive organic component as essential components. ) Is disclosed.

Description

Glass frit for photosensitive conductive paste

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to glass frits for photosensitive conductive pastes used for forming high-definition patterns in plasma display panels, plasma address liquid crystal display panels, and other electrical and electronic circuits.

[Background of invention]

In recent years, the demand for miniaturization, high density, high definition, and high reliability has increased in circuit materials and displays, and accordingly, there is a demand for technological improvement in pattern processing technology. In particular, various methods have been proposed as miniaturization of conductor circuit patterns, which are indispensable for miniaturization and high density.

For example, plasma display panels (PDPs) are capable of high-speed display compared to liquid crystal panels, and are easy to enlarge in size, and thus have penetrated into fields such as OA devices and information display devices. In addition, progress in the field of high quality television and the like is very expected.

With the expansion of this use, the color PDP which has a fine PDP and many display cells attracts attention. The PDP displays plasma by generating plasma discharge between opposing anode and cathode electrodes in a discharge space provided between the front glass substrate and the rear glass substrate and emitting light from a gas enclosed in the discharge space. In this case, the anode and the cathode electrodes on the glass substrate are arranged so that a plurality of linear electrodes are arranged in parallel, so that the electrodes of each other face each other through a slight gap, and overlap each other so as to face in the direction in which the mutual linear electrodes cross. Among the PDPs, the surface discharge type PDP having a three-electrode structure suitable for color display by phosphors has a plurality of electrode pairs that are a pair of display electrodes adjacent to each other in parallel and a plurality of address electrodes orthogonal to each electrode pair.

The address electrode is formed by printing a conductive paste such as silver paste on a glass substrate and firing the same using a printing mask having a mask pattern corresponding to the address electrode by screen printing. However, in the screen printing method, even if the optimization of the mask pattern accuracy, squeeze hardness, printing speed, dispersibility, etc., the width | variety of an electrode pattern could not be narrowed to 100 micrometers or less, and fine patterning had a limit. Moreover, in the screen printing method, since the degree of a printing mask depends on the degree of mask making, a dimension error of a mask pattern will become large when a printing mask becomes large. For this reason, in the case of a large area PDP of 30 inches or more, production of a high-definition PDP is becoming increasingly difficult technically.

In the PDP, there are a transmissive type and a reflective type. In the reflective type, an address electrode and a partition wall (rib) of an insulating layer are provided on the light emitting layer side of the back glass, and a phosphor is formed thereafter. After printing an address electrode with an electrically conductive paste and drying, an insulating glass paste is printed according to a predetermined height and width by a barrier printing mask, but is overlaid and printed 15 times in a barrier rib having a height of 200 µm before firing. Thereafter, the conductive paste and the insulating paste are baked together to form an address electrode and a partition wall. However, the larger the size of the PDP is, the more the PDP is aligned with respect to one end of the glass substrate. At the other end of the glass substrate, the pattern pitch of the conductive paste (depending on the precision of the printing mask) and Since the pattern pitch of the partition printing mask accumulates, a large position shift occurs between the address electrode and the partition wall. For this reason, a high-definition electrode pattern cannot be obtained, and the enlargement becomes very limited, and the problem needs to be solved.

As a method of improving the shortcomings of these screen printings, after the insulating paste is fired, the conductive paste is printed and fired to improve the electrode shape, the photolithography technique is used for forming the anode electrode, and the photoresist is used. The electrically conductive paste by photolithography technique is proposed (refer patent documents 1-3).

Patent Document 1: Japanese Patent Application Laid-open No. Hei 1-206538

Patent Document 2: Japanese Patent Application Laid-Open No. 1-296534

Patent Document 3: Japanese Patent Application Laid-Open No. 63-205255

SUMMARY OF THE INVENTION [

However, the existing technology is not sufficient as a technology that satisfies low resistance and enlargement at the same time in addition to the finer pattern formation which is recently required.

In finer pattern formation, a photolithography technique is required. For this purpose, in addition to electroconductivity as an electrode, photosensitivity is required, but when the refractive indices of the organic and glass components of the paste are different, diffuse reflection occurs at both interfaces, and a fine pattern is obtained. I do not lose.

In addition, when low resistance is pursued, it is considered that the conductive powder in the paste may be increased. However, in order to increase the adhesion strength with the glass substrate, the glass component in the paste is required, and this amount and component are very important. For adhesion with the substrate, the thermal expansion coefficient must be matched to the substrate, and the deterioration temperature also needs to be low.

In addition, in order to be able to produce a fine pattern with high accuracy, the particle size of the frit is also important, but this diameter is not good, but the balance of adhesiveness and sintering of the glass component is necessary.

As such, the composition and properties required for the conductive paste are constantly changing with advances in circuit materials and displays, and the current situation is that new performance is required for paste materials that satisfy them.

According to this invention, softening point is 480-540 degreeC, refractive index exists in the range of 1.5-1.7, and 5-50 mass% is contained in the photosensitive electrically conductive paste which has electroconductive powder and the photosensitive organic component as an essential component for the photosensitive electrically conductive paste Glass frit is provided.

In the photosensitive conductive paste for the glass frit, the thermal expansion coefficient of the 30 ℃ ~ 300 ℃ 95 × 10 -7 / ℃ ~ 115 × 10 or may be ^-7 / ℃.

[details]

In the glass frit for photosensitive conductive paste, a high-definition pattern resolution can be obtained by the photolithography method, and an electrode pattern having low resistance can be formed, and in addition, the paste according to the reaction of the glass frit and the organic component can be formed. A glass frit can be provided which can suppress the thickening.

The present invention imparts photosensitivity to a conductive paste and uses photolithography technology to enable formation of fine and low resistance electrodes efficiently.

The conductive powder to be used may be a powder having conductivity, but is preferably one or more selected from the group of Ag, Au, Pd, Ni, Cu, Al, and Pt, and is 600 ° C. or less on a glass substrate. Low resistance electroconductive powder which can be baked at temperature is used.

In the present invention, the glass frit is capable of firmly baking the conductive powder on the glass substrate, and has the effect of lowering the effect of the sintering aid for sintering the conductive powder and the conductor resistance.

In the photosensitive conductive paste of the present invention, SiO ₂ is 0 to 9, B ₂ O ₃ is 50 to 55, Al ₂ O ₃ is 12 to 20, ZnO is 0 to 12, MgO, CaO, SrO, and BaO in mass%. the, at least one or more _{5 ~ 17, Li 2 O,} Na 2 O, K 2 O of the glass including at least one or more 10 ~ 20, P ₂ O ₅ to the _{0 ~ 10, ZrO 2 0 ~} 3 It is preferable to contain 5-50 mass of frit. If it is this range, the glass frit which can firmly bake a conductor film on a glass substrate at 500-600 degreeC is obtained.

SiO ₂ is a glass forming component, which can form stable glass by coexisting with B ₂ O ₃ , which is another glass forming component, and may contain up to 9% (mass%, which is the same also below). If it exceeds 9%, heat resistance temperature will increase and baking will become difficult on a glass substrate below 600 degreeC.

B ₂ O ₃ is the same glass-forming component as SiO _2, and facilitates glass melting, so that the baking temperature is 500 to 600 ° C. so as not to damage the electrical, mechanical and thermal properties such as electrical insulation, strength, and coefficient of thermal expansion of the conductive paste. It is formulated to control in the range of. It is preferable to make it contain in 50 to 55% in glass. If it is less than 50%, the fluidity of glass will become inadequate, sinterability will be impaired and adhesive strength will fall, while if it exceeds 55%, the softening point of glass will become high too much and sinterability will be impaired. More preferably, it is 50 to 53% of range.

ZnO lowers the softening point of the glass and adjusts the thermal expansion coefficient to an appropriate range, and may contain up to 12% in the glass. When it exceeds 12%, the viscosity of the paste rises in a short time by reacting with the photosensitive component in the paste. More preferably, it is 0 to 6% of range.

Al ₂ O ₃ imparts adequate fluidity to the glass, and also has a function of increasing the chemical resistance of the glass, and the content is 12 to 20%. If it is less than 12%, the chemical resistance of glass will become inadequate, and the elution amount of the alkali ion in glass will increase, and the viscosity of a paste will rise. If it exceeds 20%, the flowability of the glass deteriorates, and the sintering property is impaired. More preferably, it is 13 to 17% of range.

MgO, CaO, SrO, and BaO impart fluidity to the glass as appropriate, and have an effect of increasing the chemical resistance of the glass, and contain at least one or more of these at least 5 to 17%. If it is less than 5%, the chemical resistance of the glass will be insufficient, the amount of alkali ions in the glass will increase, and the viscosity of the paste will rise, while if it exceeds 17%, the coefficient of thermal expansion of the glass will be too high.

R ₂ O (Li ₂ O, Na ₂ O, K ₂ O) is to lower the softening point of the glass, to impart fluidity appropriately, and to adjust the coefficient of thermal expansion to an appropriate range. It is preferable to contain in the range of. If it is less than 10%, the above effect cannot be exhibited, while if it exceeds 20%, the coefficient of thermal expansion is excessively increased, and the amount of alkali ions in the glass is increased, resulting in an increase in the viscosity of the paste.

Further, it is possible to suppress the elution of alkali ions in the glass, by the mass ratio of the mass ratio of _{Li 2 O / K 2 O 0.2} ~ 0.5, Na 2 O / K 2 O of 0.6 to 1.5. Departing from this range increases the amount of alkali ions eluted in the glass, and the viscosity of the paste rises.

P ₂ O ₅ is a glass forming component, and coexists with SiO ₂ , which is another glass forming component, to form stable glass and increase chemical resistance, and is contained in an amount of 0 to 10%. If it exceeds 10%, the softening point becomes high, the fluidity is insufficient, and the sintering property is impaired. In addition, the amount of co-existence with the SiO ₂ is preferably an SiO ₂ + P ₂ O ₅ from 2 to 10%. If it is less than 2%, the formation of the glass becomes unstable, while if it exceeds 10%, the flowability of the glass is lowered, and it becomes difficult to obtain a dense sintered body.

ZrO ₂ has the effect of improving the chemical resistance of the glass and is contained in the range of 0 to 3%. More preferably, it is 0.1 to 3% of range.

The particle diameter of the glass frit sets the maximum particle diameter to 8 µm or less. When it exceeds 8 micrometers, when the photosensitive electrically conductive paste is formed by high density and high definition, the problem which raises a local electrically conductive resistance arises. Preferably it is the range of 2-6 micrometers. An average particle diameter is an important factor which determines the sinterability of the photosensitive electrically conductive paste and adhesiveness with a glass substrate, and is made into the range of 0.5-3 micrometers. If it is less than 0.5 micrometer, the elution amount of the alkali ion in glass will increase and the viscosity of a paste will rise, and if it exceeds 3 micrometers, adhesiveness with a glass substrate will fall. Preferably it is the range of 0.5-2 micrometers.

As glass frit content in the photosensitive electrically conductive paste, it is preferable that it is 5-50 mass%. Since glass frit is electrically insulating, when content exceeds 50 mass%, since the resistance of an electrode increases, it is unpreferable. At 5 mass% or less, the strong adhesive strength of an electrode film and a glass substrate is hard to be obtained.

From the ease of pattern formation, it is preferable that the refractive index of a glass frit exists in the range of 1.5-1.7. Generally, the glass used as an insulator has the refractive index of about 1.5-1.9. When using the photosensitive glass paste method, when the average refractive index of an organic component differs significantly from the average refractive index of a glass powder, reflection and scattering in the interface of a glass powder and a photosensitive organic component become large, and a fine pattern is not obtained. . Since the refractive index of a general organic component is 1.45-1.7, in order to improve pattern formation, it is preferable to match the refractive index of a glass frit and an organic component, and to make the average refractive index of a glass frit 1.5-1.7. In addition, in order to improve pattern formation property, 1.5-1.6 are more preferable.

[Examples 1-4 and Comparative Examples 1-4]

The glass frit contains finely divided silica as SiO ₂ source, boric acid as B ₂ O ₃ source, alumina as Al ₂ O ₃ source, zincation as ZnO source, magnesium oxide as MgO source, calcium carbonate as CaO source, Strontium carbonate as SrO source, barium carbonate as BaO source, lithium carbonate as Li ₂ O source, sodium carbonate as Na ₂ O source, potassium carbonate as K ₂ O source, boron phosphate as P ₂ O ₅ source, Zircon was required as ZrO ₂ member. After combining these so as to have a desired low melting point glass composition, the mixture is put into a platinum crucible, and heated and melted in an electric heating furnace for 1100 to 1200 ° C. for 1 to 2 hours. Examples 1 to 4 in Table 1 The glass of the composition shown to the comparative examples 1-4 of Table 2 was obtained.

A portion of the glass was poured into the mold and provided as a block for measuring thermal properties (thermal expansion coefficient, softening point, and refractive index). The remaining glass was formed into flakes by a quench twin roll forming machine, and was pulverized in a powder form with an average particle diameter of 0.5 to 3 µm and a maximum particle diameter of less than 8 µm in a pulverizer.

The softening point was taken as the temperature when the viscosity coefficient (eta) = 10 ^7.6 was reached using the littorton viscometer. In addition, the thermal expansion coefficient was calculated | required from the amount of elongation in 30-300 degreeC when heated up at 5 degree-C / min using a thermal expansion system.

(Production of Photosensitive Paste)

The remaining glass frit for photosensitive conductive paste was dispersed in an organic component containing a photosensitive compound to obtain a photosensitive paste.

With respect to the obtained photosensitive paste, the paste viscosity [V1] immediately after dispersion and the paste viscosity [V2] after standing in the 5 ° C. cold room for 24 hours were measured, and the reaction with the photosensitive component showed that the case where [V2 / V1] was less than 1.2. It was judged that there was no reaction with the photosensitive component in the case where it was determined that there was no ◎ and in the range of 1.2 to 1.5, but it was judged that there was no problem in practical use.

Moreover, the adhesive tape was affixed on the baking film, the thing with no peeling was made into (circle) and the thing with peeling was x, and adhesive strength was evaluated.

(result)

As shown in Examples 1-4 in Table 1, in the composition range of this invention, the raise of the paste viscosity by reaction with the photosensitive component is suppressed, and a plasma display panel, a plasma address liquid crystal display panel, etc. It can use suitably for the glass frit for photosensitive electrically conductive pastes used for the formation of the high-definition pattern in an electric / electronic circuit.

On the other hand, in Comparative Examples 1 to 4 in Table 2, which deviate from the composition range of the present invention, preferable physical property values and adhesive strength were not obtained, and an increase in paste viscosity due to reaction with the photosensitive component was confirmed, resulting in a high-definition pattern. It cannot be applied as a glass frit for photosensitive conductive paste used as the photosensitive paste used for formation.

Claims (12)

Softening point is 480-540 degreeC, refractive index exists in the range of 1.5-1.7, 5-50 mass% is contained in the photosensitive electrically conductive paste which has an electroconductive powder and a photosensitive organic component as an essential component,
By mass%, _{5 or more selected} from 0 to 9 for SiO ₂ , 50 to 55 for B ₂ O ₃ , 12 to 20 for Al ₂ O ₃ , 0 to 12 for ZnO, and MgO, CaO, SrO, and BaO. _{~ 17, Li 2 O, Na} 2 O, the glass frit for K ₂ O comprises at least one member selected from 10 ~ 20, P ₂ O ₅ 0 to 10, ZrO ₂ 0 to 3, a photosensitive conductive paste. delete The method of claim 1,
Li ₂ O / K ₂ O weight ratio is _{0.2 ~ 0.5, Na 2 O /} K 2 O of the glass frit for a photosensitive conductive paste mass ratio of 0.6 ~ 1.5 in. delete The method according to claim 1 or 3,
The thermal expansion coefficient of the 30 ℃ ~ 300 ℃ 95 × 10 -7 / ℃ ~ 115 × 10 -7 / ℃ the glass frit for a photosensitive conductive paste. The method according to claim 1 or 3,
The glass frit for photosensitive electrically conductive paste whose largest particle diameter is 8 micrometers or less and average particle diameter is 0.5 micrometer-3 micrometers. The method of claim 5,
The glass frit for photosensitive electrically conductive paste whose largest particle diameter is 8 micrometers or less and average particle diameter is 0.5 micrometer-3 micrometers. The method of claim 3,
The photosensitive conductive paste, the glass frit for the total of SiO ₂ and P ₂ O _{5 2} ~ 10% by weight. The method of claim 5,
The photosensitive conductive paste, the glass frit for the total of SiO ₂ and P ₂ O _{5 2} ~ 10% by weight. The method according to claim 6,
The photosensitive conductive paste, the glass frit for the total of SiO ₂ and P ₂ O _{5 2} ~ 10% by weight. The method of claim 7, wherein
The photosensitive conductive paste, the glass frit for the total of SiO ₂ and P ₂ O _{5 2} ~ 10% by weight. (a) conductive powder,
(b) a photosensitive organic component,
(c) A photosensitive electrically conductive paste containing 5-50 mass% of glass frits whose softening point is 480-540 degreeC and whose refractive index exists in the range of 1.5-1.7,
The glass frit is
By mass%, _{5 or more selected} from 0 to 9 for SiO ₂ , 50 to 55 for B ₂ O ₃ , 12 to 20 for Al ₂ O ₃ , 0 to 12 for ZnO, and MgO, CaO, SrO, and BaO. Photosensitive conductive paste, characterized in that 10 to 20, P ₂ O ₅ 0 to 10, ZrO ₂ 0 to 3 at least one selected from ~ 17, Li ₂ O, Na ₂ O, K ₂ O. .