JP2002012446A - Boric phosphoric acid glass for forming transparent insulation coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide low permittivity glass suitable for coating an electric conductor pattern on a substrate, etc., with moderate coefficient of thermal expansion, low thermal expansion yielding point, and glass transition point, and less prone to deposit devitrification even in melting-cooling process or reheat treating without liquation of P2O5-B2O3. SOLUTION: The boric phosphoric acid glass for forming transparent insulating coating glass has glass component in the range of 40-50 wt.% P2O5, 15-30 wt.% B2O3, 15-35 wt.% ZnO, 0-15 wt.% BaO, 4-10 wt.% K2O and/or Na2O, and the permittivity of 6.0 or less under room temperature at 1 MHz, has ingradients substantially free from lead and bismuth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boric acid-based substantially PbO, which is suitable for insulatingly coating a conductor and a semiconductor pattern disposed on a substrate such as a plasma display panel and a fluorescent display tube. The present invention relates to a transparent glass having a low melting point (thermal expansion yielding point) containing no Bi ₂ O ₃ .

[0002]

2. Description of the Related Art Conventionally, lead-based glass has been widely used as a glass having a low melting point, for example, a glass for forming a transparent insulating film on a substrate. Although the lead component is an important component for lowering the melting point of glass, it has a serious adverse effect on the human body and the environment, and has recently been tending to avoid its use.

In order to lower the melting point of glass, it is known to introduce a bismuth component, a tellurium component, etc. into the glass. However, since these are heavy metals similar to lead, their effects on the environment are denied. Absent.

In order to lower the melting point of glass, alkali metals are components that are also heavily used. However, the introduction of an excessive amount degrades electrical properties such as electrical insulation. It is.

[0005] Regarding the known art of phosphate-based glass containing no alkali metal and containing no lead, for example, Japanese Patent Application Laid-Open No.
The -87531 discloses, although many glass glaze of P ₂ O ₅ component is disclosed, it is for the purpose of glaze, P ₂
This is different from the component composition system of the present invention, for example, the amount of O ₅ minutes is excessive.
JP-A-3-83836 discloses a glass to be used for a patterning ink containing B ₂ O ₃ and a ZnO component in a small amount and containing a Li ₂ O component as an essential component. However, it is not suitable for forming an insulating and transparent film containing Li ₂ O.

[0006] Separately, Japanese Patent Application Laid-Open No. 5-132339 discloses that B ₂ O ₃
Contains no components, requires a Li ₂ O component, SnO ₂ , WO ₃ , MoO ₃
A low-temperature glass containing components and the like as essential components is disclosed, but the component system is different from the present invention.

[0007] Alternatively, JP-A-8-183632 discloses that
Although a low-melting glass having a low glass transition point which requires Al ₂ O ₃ minutes is disclosed, the component composition range is different from that of the present invention.

Further, JP-A-9-235136 and JP-A-11-20
No. 9146, JP-A-11-314936 and the like disclose a zinc phosphate-based low-melting glass containing SnO as an essential component, and a sealing composition. It is also intended for sealing.

Further, in any of the prior arts, attention is paid to the dielectric constant, and there is no disclosure or suggestion that the value is set to a specific value or less.

[0010]

DISCLOSURE OF THE INVENTION The present invention relates to a boric acid system suitable for insulatingly covering a conductor and a semiconductor pattern disposed on a base material and having a melting point substantially free from PbO and Bi ₂ O _3. It is a low transparent glass, and the low melting glass is an excellent insulating material, and at the same time, reduces the power consumption during operation of a plasma display panel or the like by lowering the dielectric constant.

[0011]

According to the present invention, the glass composition is expressed in terms of weight%, P ₂ O ₅ 40-50, B ₂ O ₃ 15-30, ZnO 15-35, Ba
It is a range of O 0-15, K ₂ O and / or Na ₂ O 4-10, and is a borophosphate-based glass for forming a transparent insulating film substantially free of a lead component and a bismuth component.

By setting the above composition range, the dielectric constant at 1 MHz at room temperature can be set to 6.0 or less.

In the above, the coefficient of thermal expansion at 30 to 300 ° C. is 6
It is preferable that the thermal expansion deformation yield point is 5 to 90 × 10 ⁻⁷ / ° C. and 570 ° C. or less.

Further, the crystal deposition temperature by differential thermal analysis
Preferably, the glass transition temperature is 150 ° C. or higher.

[0015] Incidentally, the thermal expansion deformation point is sometimes referred to as softening point, Littleton point obtained by measuring by Littleton viscometer (10 ⁶ poises equivalent temperature) many cases referred to as softening point, also the mutually slightly Because there is a temperature difference of
In the present invention, it is referred to as a thermal expansion yielding point to distinguish it from the Littleton point.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the glass component is based on boric acid-zinc, and by specifying the composition range,
Physical properties required for forming a transparent insulating film in a plasma display or the like can be satisfied, and in particular, power consumption can be reduced by keeping the dielectric constant low, and PbO, Bi ₂
By not including O ₃ , there is no effect on the human body and the environment. Alkali metals (K ₂ O, Na ₂
An appropriate content of O) stabilizes the glass and gives an appropriate coefficient of thermal expansion.

The component composition of the borophosphate glass of the present invention is set in the following range. P ₂ O ₅ is an important glass-forming component, and is contained in the glass in the range of 40 to 50% (expressed by weight%, the same applies to the following description). If it is less than 40%, glass formation becomes unstable, and heat treatment causes devitrification. If it exceeds 60%, the thermal expansion yield point will rise excessively.

B ₂ O ₃ is a glass-forming component and is essential for facilitating glass melting and giving the glass an appropriate coefficient of thermal expansion. The B ₂ O ₃ is contained in the glass in the range of 15 to 30%. If it is less than 15%, it is difficult to obtain stable glass formation,
If it exceeds 30%, it tends to be immiscible with P ₂ O ₅ in the above content range.

[0019] K ₂ O, Na ₂ O is intended that the glass to stabilize, as essential in helping to have an appropriate thermal expansion coefficient, K ₂ O
And / or Na ₂ O is contained in the glass in the range of 4 to 10%. If the amount is less than 4%, the effect is insufficient. If the amount exceeds 10%, the electrical properties such as the electrical insulation of the glass are impaired, and the thermal expansion of the glass is increased. In the same alkali metals, the presence of Li ₂ O should not be used because it tends to impair the electrical properties such as electrical insulation and increases the cost of glass raw materials. Therefore, the alkali metals in the present invention are K ₂ O and / or Na ₂ O, and it is more preferable to use K ₂ O or to use only K ₂ O for most of them.

ZnO lowers the thermal expansion yield point of the glass and imparts appropriate fluidity. In general, in a phosphate glass structure having a large thermal expansion coefficient, Zn ions intervene to appropriately reduce the thermal expansion coefficient. It is contained in the range of 15-35%. If it is less than 15%, the above effect cannot be exerted, and particularly, the thermal expansion coefficient of the glass becomes excessive. If it exceeds 35%, glass formation becomes difficult.

BaO is included as necessary in lowering the thermal expansion yield point of the glass, imparting appropriate fluidity, and adjusting the thermal expansion coefficient to an appropriate range. The content of BaO is 15% or less in the glass. If it exceeds 15%, the coefficient of thermal expansion increases excessively.

Considering the thermal expansion coefficient, the thermal expansion yield point, the glass melting property, the dialysis-removing property, and the like, (Na ₂ O + K ₂ O
Total) / (is preferably a weight ratio of P total _{2 O 5 + B 2 O 3} ) is in the range of 0.05 to 0.15, is less than 0.05 is difficult to reduce sufficiently the thermal expansion deformation point of the glass, 0.15 Exceeding this may impair the electrical properties of the glass.

Al ₂ O ₃ can be contained in the glass in an amount of 1% or less in order to give the glass an appropriate thermal expansion coefficient and a thermal expansion yield point. The divalent metal oxides of MgO, CaO, and SrO also give the glass an appropriate thermal expansion coefficient and thermal expansion yield point, and in order to improve the glass melting property, one or more of the above-mentioned ones is in a range of 3% or less. Can be contained.

If the amount of PbO, Bi ₂ O _3, etc. mixed into glass raw materials or cullet as impurities is within the range of 0.3% or less in the low-melting glass, respectively, the above-mentioned adverse effects, that is, the human body and the environment And there is almost no effect on electrical characteristics.

As the substrate in the present invention, a transparent glass substrate, particularly a soda-lime-silica glass or a glass similar thereto (high strain point glass) is generally used, and its thermal expansion coefficient is 30 ° C. to 300 ° C. It is about 70 to 90 × 10 ⁻⁷ / ° C., and the low melting point glass of the present invention is made to approximate to this, thereby preventing adverse effects such as peeling of the formed film and distortion of the substrate.

The base material made of the above-mentioned glass has a thermal expansion deformation point of about 620 ° C. or more, whereas that of the glass of the present invention is sufficiently low at 570 ° C. or less, so that the baking temperature is correspondingly lowered. It is possible to suppress softening deformation and heat shrinkage of the substrate during baking.

The glass of the present invention can excite a rare gas in the discharge space with a low applied voltage in a plasma display or the like by making the dielectric constant at room temperature 1 MHz at 1 MHz or less, facilitating the light emission of the phosphor, and hence the consumption. Electric power can be reduced as much as possible. In addition, if the volume resistivity at room temperature is 10 ¹⁰ Ωcm or more, it is in the category of an insulator.
Even at ℃, the volume resistivity is as high as 10 ¹¹ Ω · cm or more, and it has a good electric insulating property for insulatingly covering conductors and semiconductor patterns.

Further, the crystal deposition temperature by differential thermal analysis
Glass transition temperature: Tc−Tg (° C.) of 150 ° C. or higher indicates that precipitation of devitrification and opacity of glass hardly occur during heat treatment at a temperature higher than the glass transition point, and more preferably Tc− It is desirable that Tg (° C.) be 200 ° C. or higher.

[0029]

[Example] [Preparation of low melting point glass] Phosphoric acid as a P ₂ O ₅ source, boric acid as a B ₂ O ₃ source, or boron phosphate as a composite material thereof, sodium carbonate as a Na ₂ O source, Using potassium carbonate as a K ₂ O source, barium carbonate as a BaO source, and zinc white as a ZnO source, mixing them to obtain a desired low-melting glass composition, then putting only the powder raw material into a platinum crucible, Was dropped, and a reaction was performed. Further, the reaction was allowed to proceed at 500 ° C. for 1 hour in an electric heating furnace, and then at 1000 to 1100 ° C., 1 to 1 in the electric heating furnace.
After heating and melting for 2 hours, the mixture was poured out onto a carbon plate and gradually cooled to obtain glasses having compositions shown in Examples and Comparative Examples in Tables 1 to 3. The glass samples were subjected to the following tests.

[Sample Observation-Presence or Absence of Vitrification] The glass sample was observed under a magnifying glass, and those having no devitrification and other crystalline materials were evaluated as good (○), and those observed were evaluated as poor (×).

[Measurement of DC Volume Resistivity] A glass sample having a size of 50 mmφ × 1 to 2 mm thick was cut out from slowly cooled glass, and the surface was polished with fine abrasive grains. After further washing and drying, a main electrode, a guard electrode and a counter electrode were formed by gold evaporation to obtain a measurement sample. The sample was set in a volume resistivity measuring apparatus, and after maintaining a high vacuum, the temperature was raised to a predetermined temperature of 250 ° C., and then the direct current volume resistivity of the sample was measured by a three-terminal method. The DC volume resistivity at the above temperature is 10 ¹¹ Ωcm
Above is satisfactory.

[Measurement of dielectric constant] 50 mm from slowly cooled glass
A glass sample having a size of φ × 1 to 2 mm was cut out, the sample was set on a measurement bridge, the sample capacitance at room temperature was measured, and the dielectric constant was calculated from the electrode area and the sample thickness. The measurement frequency was 1 MHz. By setting the dielectric constant to 6.0 or less, power consumption can be significantly reduced.

[Measurement of Thermal Expansion Coefficient] A glass sample was cut into a predetermined size, and then set on a differential thermal dilatometer.
Measure the elongation by heating at the rate of minutes, record the temperature, 30 ~ 300 ℃
The average coefficient of thermal expansion α (× 10 ⁻⁷ / ° C.) was calculated. In addition,
The coefficient of thermal expansion approximates the coefficient of thermal expansion of the substrate,
The thermal expansion coefficient at -300 ° C is 65-90 × 10 ^-7 / ° C.

[Measurement of glass transition point and thermal expansion _yield point] The glass transition point (Tg (° C)) and thermal expansion _yield point (T _yield (° C)) were measured from the above thermal expansion data. The thermal expansion yield point is
It should be 570 ° C or less.

[Measurement of Crystal Precipitation Temperature, Calculation of Crystal Precipitation Temperature-Glass Transition Point] A finely pulverized glass sample was set in a differential thermal analyzer, and the temperature was raised to 1000 ° C. at a rate of 10 ° C./min. The exothermic peak was measured and recorded. Among these, the exothermic peak based on the crystal precipitation was defined as the crystal deposition temperature (Tc (° C.)), and the presence or absence of the crystals was confirmed under a magnifying glass. From the value obtained by subtracting the glass transition point (Tg) from the crystal precipitation temperature (Tc), a temperature difference between the crystal precipitation temperature and the glass transition point: Tc−Tg
(° C.) was calculated. It should be noted that the larger the value of Tc-Tg (° C.) during the heat treatment at or above the glass transition point, the more difficult it is to show that precipitation of devitrification and opacity of the glass do not occur.
It is preferable that ≧ 150 (° C.).

[Measurement of Acid Etching Rate of Insulating Film] When a conductor pattern or a semiconductor pattern is formed on a substrate and the insulating film is coated with a glass film having a low softening point (thermal expansion yielding point), the substrate surface is temporarily removed. After covering the entire conductor / semiconductor pattern with the glass coating, the glass coating covering the end is removed by acid etching so as to expose the end of the conductor / semiconductor pattern and connect to an external lead wire. There are cases. In this case, it is preferable that the glass coating is easily removed by acid etching. Specifically, it is desirable that the removal rate in the thickness direction of the coating with a 7% by weight aqueous nitric acid solution at room temperature (25 ° C.) be 3 μm / min or more. It is. Etching was performed under the above conditions, and the removal rate per minute was measured.

[Results] The results of various tests are shown in Tables 1 to 3.

As is clear from Tables 1 to 3, the examples according to the present invention have an appropriate glass thermal expansion coefficient, a low thermal expansion deformation point and a glass transition point, and have a melting-cooling process and a re-heat treatment. In this case, devitrification hardly precipitates, there is no immiscibility of P ₂ O ₅ —B ₂ O _{3, and} a remarkable effect is exhibited in coating a conductive pattern on a substrate, particularly a glass substrate. On the other hand, the comparative example cannot satisfy the above thermophysical properties.

[0039]

[Table 1] Note: (1) in the table indicates that no crystallization peak occurred.
(The same applies to the following)

[0040]

[Table 2] Note:-in the table is not measured because it was not crowed. (The same applies to the following)

[0041]

[Table 3]

[0042]

According to the present invention, suitable glass thermal expansion coefficient, low thermal expansion deformation point, has a glass transition temperature, melt - hardly devitrification precipitates in the cooling process and reheating, P ₂ O ₅ −
There is no immiscibility of B ₂ O ₃ , which is suitable for covering a conductive pattern on a substrate or the like. By setting the dielectric constant to a specific value or less, power consumption in a plasma display or the like can be reduced as much as possible.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor, Panshi Machishita 1510 Oguchicho, Matsusaka-shi, Mie Central Glass F-term in Glass Research Laboratories, Inc. (reference) 4G062 AA08 AA09 BB09 DA01 DB01 DC04 DD05 DE04 DE05 DF01 EA01 EA10 EB01 EB02 EB03 EC01 EC02 EC03 ED01 EE01 EF01 EG01 EG02 EG03 EG04 FA01 FA10 FB01 FC01 FD01 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HHJ KK KKHH KK NN32

Claims (3)

[Claims] (1) A glass composition having a weight percentage of P ₂ O ₅ 40-50, B ₂ O
₃ 15-30, ZnO 15-35, BaO 0-15, K ₂ O and / or Na ₂ O 4-10, and a dielectric constant at 1 MHz at room temperature of 6.0 or less, substantially a lead component, bismuth A boric acid-based glass for forming a transparent insulating film, characterized by containing no component. 2. The thermal expansion coefficient at 30 to 300 ° C. is 65 to 90 × 10 ^-7 /
The borophosphate-based glass for forming a transparent insulating film according to claim 1, wherein the glass has a thermal expansion deformation point of 570 ° C or lower. 3. The method according to claim 1, wherein a difference between a crystal deposition temperature and a glass transition temperature by differential thermal analysis is 150 ° C. or more.
Or the borophosphate-based glass for forming a transparent insulating film according to 2.