JP2005219942A - Lead-free low melting point glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide lead-free low melting point glass having no continuous pore, small influence on human body or environment and excellent electric insulating property and free from yellowing. <P>SOLUTION: The SiO<SB>2</SB>-B<SB>2</SB>O<SB>3</SB>-ZnO-R<SB>2</SB>O-RO-based lead-free low melting point glass contains SiO<SB>2</SB>of 0.1-8, B<SB>2</SB>O<SB>3</SB>of 30-45, ZnO of 15-35, Li<SB>2</SB>O of 0.1-5, R<SB>2</SB>O (Na<SB>2</SB>O+K<SB>2</SB>O excluding Li<SB>2</SB>O) of 0-10 and RO (MgO+CaO+SrO+BaO) of 10-40, by wt.%, wherein Sn of 0.1-10 and Cu of 0.1-5 by wt.% expressed in terms of oxide can be contained, the weight ratio of (B<SB>2</SB>O<SB>3</SB>+Li<SB>2</SB>O+R<SB>2</SB>O)/SiO<SB>2</SB>is >8 and ≤30, the weight ratio of Li<SB>2</SB>O/SiO<SB>2</SB>is ≥0.2 and ≤1, the weight ratio of B<SB>2</SB>O<SB>3</SB>/ZnO of ≥1 and ≤2.5, the coefficient of linear expansion at 30-300°C is (65-95)×10<SP>-7</SP>/°C and the softening point is ≥500°C and ≤630°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an insulating coating material for an electronic material substrate typified by a plasma display panel, a liquid crystal display panel, an electroluminescence panel, a fluorescent display panel, an electrochromic display panel, a light emitting diode display panel, a gas discharge display panel, and the like. The present invention relates to a low melting point glass used as a sealing material.

  With the recent development of electronic components, many types of display panels such as plasma display panels, liquid crystal display panels, electroluminescence panels, fluorescent display panels, electrochromic display panels, light emitting diode display panels, and gas discharge display panels have been developed. Has been. Among them, a plasma display panel (hereinafter abbreviated as PDP) is attracting attention as a thin and large flat color display device. In a PDP, a large number of cells are provided between a front substrate and a rear substrate used as a display surface, and an image is formed by performing plasma discharge in the cells. This cell is partitioned by partition walls, and an electrode is formed for each pixel unit in order to control the display state of each pixel forming an image.

  As shown in FIG. 1, the PDP panel is sandwiched between a front glass plate 1 and a back glass plate 2, and the front glass plate 1 and the back glass plate 2 are sealed with a sealing material 3. There are a front glass plate 1, a transparent electrode 4, a bus electrode 5, a transparent dielectric 6 and a protective film at the front of the panel, and a back glass plate 2, an address electrode 8, a white dielectric 9, and a phosphor 10 on the back. There is a partition wall 11. Generally, the ultraviolet rays 12 become visible light 13 due to the action of the phosphor 10.

  For example, a transparent electrode (ITO or the like), a bus, and an address electrode (Cr—Cu—Cr; may be Al instead of Cu) are disposed as conductors on the front or back substrate of the PDP. A dielectric layer is formed so as to cover them, and a gas is sealed between the front and back substrates on which the dielectric layer is formed to form a panel structure. By the way, low melting point glass is used for the dielectric as described above, and when forming a structure, a low melting point glass paste is applied on a substrate on which electrodes are arranged and fired to form a dielectric film. To do.

  Conventionally, lead glass has been employed for low melting glass, for example, low melting glass for coating a substrate. Although the lead component is an important component for making the glass have a low melting point, it has a great detrimental effect on the human body and the environment, and in recent years it tends to be avoided. However, when lead-based glass is changed to lead-free low-melting glass, continuous pores are formed at the interface between the formed dielectric film and the copper electrode, resulting in a problem that the sealed gas leaks after the panel is formed.

The present inventor has disclosed a SiO ₂ —B ₂ O ₃ —BaO—ZnO-based low melting glass having a transparent and electrically insulating property for covering a substrate surface directly or covering a conductor or semiconductor pattern. A low melting point having a coefficient of linear thermal expansion at 30 ° C. to 300 ° C. of (65 to 95) × 10 ⁻⁷ / ° C., a softening point of 600 ° C. or less, and a dielectric constant of 7.5 or less at room temperature and a frequency of 1 MHz. A low-melting glass for forming a film on a transparent electrode line pattern disposed on a glass, particularly a display panel substrate, is disclosed (see Patent Document 1).

In addition, for example, a plasma display material in which the contents of PbO and CuO are limited (see, for example, Patent Document 2) is used for a plasma display in which the contents of BaO + SrO + MgO are limited in addition to PbO, B ₂ O ₃ , SiO ₂ , and CaO. Materials (for example, see Patent Document 3) are disclosed. Furthermore, a low dielectric constant glass composition limited to the composition of ZnO, B ₂ O ₃ , SiO ₂ , and Al ₂ O ₃ developed for gas discharge display devices is disclosed (for example, see Patent Document 4).
Japanese Patent Laid-Open No. 2002-12445 JP 2001-52621 A JP 2001-80934 A JP-A-9-278482

  In electronic materials such as PDP, lead-free is being studied due to environmental problems, and on the other hand, more strict manufacturing conditions and quality are required. For this reason, what has not been a problem in the past is also highlighted and may be taken up as a major problem. For example, there is a problem of continuous pores generated beside electrodes used in PDPs, that is, continuous pores generated at the portion where the low melting point glass and the conductor portion of the metal electrode are in contact. This is a new problem that has become apparent in recent years and has not been seen in the past. Therefore, until now, almost no awareness was given, and the occurrence of such problems was not recognized. It is also unclear what manufacturing conditions are affecting the continuous pore problem, and of course the countermeasures are not known, and as a major problem in electronic materials such as recent PDPs, industrial development is hindered. It is becoming a factor.

  Even when the disclosed literature is viewed, this continuous pore problem is not described, and an effective countermeasure is unknown. That is, the method disclosed in Japanese Patent Application Laid-Open No. 2002-12445 has an advantage that the influence on the human body and the environment is reduced and the electrical insulation is excellent. In addition, JP-A-2001-52621 and JP-A-2001-80934 show a considerable improvement against yellowing. However, it is not effective for measures against continuous pores, which is a problem in the present invention. There is also a basic problem of containing lead. Further, JP-A-9-278482 focuses on lowering the dielectric constant of glass, and the problem in the present invention is not clearly indicated.

The present invention provides a transparent insulating lead-free low-melting-point glass, the SiO ₂ by weight% _0.1~8, B 2 _{O 3} 30 to 45, 15 to 35 to ZnO, the Li ₂ O 0.1 to 5 And R ₂ O (Na ₂ O + K ₂ O, excluding Li ₂ O) 0-10, RO (MgO + CaO + SrO + BaO) 10-40, SiO ₂ —B ₂ O ₃ —ZnO—R ₂ O -RO-based lead-free low-melting glass.

  Further, the lead-free low-melting glass as described above, wherein Sn converted to an oxide contains 0.1 to 10% by weight.

  Moreover, it is said lead-free low melting glass characterized by containing 0.1-5 by weight% Cu converted into an oxide.

The lead-free low-melting glass as described above, wherein the weight ratio of (B ₂ O ₃ + Li ₂ O + R ₂ O) / SiO ₂ exceeds 8 and is 30 or less.

The lead-free low-melting glass is characterized in that the Li ₂ O / SiO ₂ weight ratio is 0.2 or more and 1 or less.

Further, the lead-free low-melting glass according to the above, wherein the weight ratio of B ₂ O ₃ / ZnO is 1 or more and 2.5 or less.

Moreover, it is said lead-free low melting glass whose linear thermal expansion coefficient in 30 degreeC-300 degreeC is (65-95) * 10 < ^-7 > / degreeC, and a softening point is 500 degreeC or more and 630 degrees C or less.

  Furthermore, it is an electronic material substrate using the above lead-free low-melting glass.

  Still further, the present invention is a PDP panel using the above lead-free low melting point glass.

  Lead-free low-melting glass that has no continuous pores that could not be solved in the past, has a small effect on the human body and the environment, is excellent in electrical insulation, and has no yellowing has been developed.

The present invention provides a transparent insulating lead-free low-melting-point glass, the SiO ₂ by weight% _0.1~8, B 2 _{O 3} 30 to 45, 15 to 35 to ZnO, the Li ₂ O 0.1 to 5 And R ₂ O (Na ₂ O + K ₂ O, excluding Li ₂ O) 0-10, RO (MgO + CaO + SrO + BaO) 10-40, SiO ₂ —B ₂ O ₃ —ZnO—R ₂ O -RO-based lead-free low-melting glass.

SiO ₂ is a glass forming component, and can coexist with B ₂ O ₃ which is another glass forming component to form a stable glass. It is preferable to contain the same. If it is less than 0.1%, the above effect is too small. However, if it exceeds 8%, the softening point of the glass rises, and the formability and workability become difficult.

For example, in the production of a PDP, an insulating film is once formed on the electrode line pattern, and then the insulating film coated on the part is dissolved and removed with an acid so as to form an electrode line extraction part on the peripheral edge of the panel. However, if the amount is excessive, the acid resistance increases more than necessary and the dissolution becomes difficult. Therefore, the weight percent of SiO ₂ is preferably 5% or less. More preferably, it is 1 to 4% of range.

B ₂ O ₃ is a glass-forming component similar to SiO ₂ , facilitates glass melting, suppresses an excessive increase in the linear thermal expansion coefficient of the glass, gives moderate fluidity to the glass during baking, and together with SiO ₂ It reduces the dielectric constant of glass. It is preferable to make it contain in 30 to 45% of range in glass. If it is less than 30%, the fluidity of the glass becomes insufficient and the sinterability is impaired. On the other hand, if it exceeds 45%, the stability of the glass is lowered. More preferably, it is 35 to 40% of range.

  ZnO lowers the softening point of glass, imparts moderate fluidity, and adjusts the linear thermal expansion coefficient to an appropriate range, and is preferably contained in the glass in a range of 15 to 35%. If it is less than 15%, the above-mentioned effect cannot be exhibited, and if it exceeds 35%, the glass becomes unstable and devitrification tends to occur. More preferably, it is 20 to 30% of range.

Li ₂ O lowers the softening point of glass, imparts moderate fluidity, and suppresses the generation of continuous pores while adjusting the linear thermal expansion coefficient to an appropriate range, and is in the range of 0.1 to 5%. It is preferable to contain. If it is less than 0.1%, the above-mentioned action cannot be exhibited, and if it exceeds 5%, devitrification tends to occur. More preferably, it is 1 to 3% of range.

R ₂ O (Na ₂ O, K ₂ O, excluding Li ₂ O) lowers the softening point of glass, imparts moderate fluidity, and adjusts the linear thermal expansion coefficient to an appropriate range. It is preferable to make it contain in 10% of range. If it exceeds 10%, the linear thermal expansion coefficient is excessively increased, and the reaction with the electrode becomes remarkable, resulting in large bubbles. More preferably, it is 3 to 7% of range.

  RO (MgO, CaO, SrO, BaO, etc.) lowers the softening point of glass, imparts moderate fluidity, and adjusts the linear thermal expansion coefficient to an appropriate range, and is contained in the range of 10 to 40%. preferable. If it is less than 10%, the above effect cannot be exhibited, and if it exceeds 40%, meltability and devitrification problems occur. More preferably, it is 20 to 30% of range.

  Moreover, it is preferable that Sn converted to an oxide contains 0.1 to 10% by weight. This is because the inclusion of Sn is often extremely effective for the problem of continuous pores occurring beside electrodes used in electronic material substrates, for example, PDPs. However, if it exceeds 10%, the glass becomes unstable, and reaction bubbles with the electrode may be generated. More preferably, it is 0.1-5%, More preferably, it is 0.1-3%.

  Moreover, it is preferable that Cu converted into an oxide contains 0.1 to 5 weight%. This is because the inclusion of Cu is often very effective for the problem of single pores occurring beside an electrode used in an electronic material substrate, for example, a PDP. However, if it exceeds 5%, the glass becomes unstable and devitrification occurs. More preferably, it is 0.1 to 1%, More preferably, it is 0.2 to 0.5%.

The weight ratio of (B ₂ O ₃ + Li ₂ O + R ₂ O) / SiO ₂ is preferably more than 8 and 30 or less. The weight ratio of (B ₂ O ₃ + Li ₂ O + R ₂ O) / SiO ₂ is important. If the ratio does not exceed 8, continuous pores are generated, and if it exceeds 30, volatilization of components during melting becomes severe. . More preferably, it is 10-20.

The weight ratio of Li ₂ O / SiO ₂ is preferably 0.2 or more and 1 or less. If it is less than 0.2, the effect of Li ₂ O is inhibited, and if it exceeds 1, stability is deteriorated.

The weight ratio of B ₂ O ₃ / ZnO is preferably 1 or more and 2.5 or less. The weight ratio of B ₂ O ₃ / ZnO is important, and if the ratio is less than 1, there is a problem that crystallization tends to occur, and if it exceeds 2.5, the softening point becomes too high. More preferably, it is the range of 1.2-2.2.

  By substantially not containing PbO, it is possible to eliminate the influence on the human body and the environment. Here, “substantially free of PbO” means an amount of PbO mixed as an impurity in the glass raw material. For example, if it is in the range of 0.3 wt% or less in the low-melting glass, there is almost no influence on the adverse effects described above, that is, the influence on the human body and the environment, the insulation characteristics, etc., and it is not substantially affected by PbO. Become.

Furthermore, it is preferable that the linear thermal expansion coefficient at 30 ° C. to 300 ° C. is (65 to 95) × 10 ⁻⁷ / ° C. and the softening point is 500 ° C. or more and 630 ° C. or less. If the linear thermal expansion coefficient deviates from (65 to 95) × 10 ⁻⁷ / ° C., problems such as peeling of the coating film and warping of the substrate occur when forming a thick film. More preferably, it is in the range of (75 to 85) × 10 ⁻⁷ / ° C. If the softening point exceeds 630 ° C., problems such as softening deformation of the substrate occur. More preferably, it is 540 degreeC or more and 590 degrees C or less.

  Furthermore, it is a substrate for electronic materials using the low melting point glass. By using the low melting point glass described above, a substrate for electronic material having no continuous pores can be obtained.

  Furthermore, the present invention is a PDP panel using the above-mentioned low melting point glass. By using the low melting point glass described above, a PDP panel without continuous pores can be obtained.

  The lead-free low-melting glass of the present invention can be used, for example, on the front plate or the back plate of PDP glass. When used as a back plate, it is used as a sealing material or a covering material, and is often used after being powdered. This powdered glass is mixed with a low expansion ceramic filler represented by mullite or alumina, a heat-resistant pigment, etc. at a ratio of 0.6 {glass / (glass + filler) weight ratio} or more, and then organically. Generally, it is kneaded with oil to form a paste.

  As the glass substrate, a transparent glass substrate, particularly soda-lime-silica glass, or similar glass (high strain point glass), or an alumino-lime borosilicate glass with little (or almost no) alkali content is used. Yes.

Hereinafter, a description will be given based on examples.
(Front glass substrate for PDP)
The front glass substrate is made of clear soda-lime glass or glass having a similar composition, thermophysical properties, and the like. A patterned transparent electrode wire, for example, an indium oxide-tin (ITO) -based or tin oxide (SnO ₂ ) -based electrode wire is applied to the surface (one surface) of the front glass substrate by a sputtering method or a CVD method.

  Further, a part of the transparent electrode line is covered, and chromium-copper-chromium (Cr-Cu-Cr) [or aluminum is used instead of copper] is formed as a bus electrode line. A transparent insulating film (hereinafter referred to as an insulating film) made of the low melting point glass according to the present invention is applied to the upper layer. The insulating film is a pre-manufactured and sized mixture of low melting glass powder and paste oil applied to the front substrate and the transparent electrode wire by screen printing, etc., and baked at 630 ° C. or less to form a thick film of about 20 μm thickness. Form. The thickness of about 20 μm is necessary and sufficient for exhibiting display performance by gas discharge and long-term stability.

Further, the production of the front glass substrate for PDP is completed by covering the insulating film and covering the protective magnesia layer by sputtering or the like.
Below, the Example which employ | adopted the low melting glass of this invention as an insulating film is shown.

(Production of low melting point glass mixed paste)
Fine silica sand as the SiO ₂ source, boric acid as the B ₂ O ₃ source, zinc white as the ZnO source, barium carbonate as the BaO source, magnesium carbonate as the MgO source, calcium carbonate as the CaO source, and strontium carbonate as the SrO source Lithium carbonate as the Li ₂ O source, sodium carbonate as the Na ₂ O source, potassium carbonate as the K ₂ O source, tin oxide as the SnO ₂ source, and copper oxide as the CuO source. After preparing these as a desired low melting-point glass composition, it puts into a platinum crucible and heat-melts in 1000-1300 degreeC and 1-2 hours in an electric heating furnace, Examples 1-5 of Table 1, Table 1 The glass of the composition shown in 2 comparative examples 1-5 was obtained.

  A part of the glass was poured into a mold, made into a block shape, and used for measurement of thermophysical properties (linear thermal expansion coefficient, softening point). The remaining glass was flaked with a rapid cooling twin roll molding machine and sized with a pulverizer into a powder having an average particle size of 2 to 4 μm and a maximum particle size of less than 15 μm.

  Next, paste oil composed of α-terpineol and butyl carbitol acetate was mixed with ethyl cellulose as a binder and the above glass powder to prepare a paste suitable for screen printing having a viscosity of about 300 ± 50 poise.

(Formation of insulating coating)
An ITO pattern film is formed on a soda-lime-based glass substrate having a thickness of 2 to 3 mm and a size of 150 mm square by a sputtering method, and the screen is opened with a mesh size of 250, taking into consideration that the film thickness after baking is about 20 μm. The paste was applied by screen printing.

  Next, after drying, baking was performed at 630 ° C. or lower for 40 minutes to form an insulating film.

  The obtained sample was subjected to the following test.

(Continuous pore observation around the electrode)
After firing the thick film on a 30 × 30 mm size glass substrate, the fractured surface was observed with a microscope.

(Stability)
After firing a thick film on a 30 × 30 mm size glass substrate, “◯” indicates that there is no crystal precipitation in the appearance inspection using a microscope, and “×” indicates that there is no crystal.

(result)
The low melting point glass composition and various test results are shown in the table.

  As shown in Examples 1 to 5 in Table 1, within the composition range of the present invention, the generation of continuous pores around the copper electrode is suppressed, and the reaction with the bus electrode is also suppressed. Therefore, it is suitable as a low-melting glass for forming a transparent insulating film, particularly as a low-melting glass for a PDP full-surface glass substrate. Examples 4 and 5 were manufactured as back substrates, but no particular problem was observed. At this time, mullite was used as the filler in Example 4, and the mixing ratio of glass and filler was 95: 5 (% by weight). In Example 5, alumina was used, and the mixing ratio of glass and filler was 85:15 (% by weight).

  On the other hand, Comparative Examples 1 to 5 in Table 2 outside the composition range of the present invention do not show preferable physical properties and preferable characteristics as a low-melting glass for coating a substrate such as PDP, but as a low-melting glass for coating a substrate such as PDP. Not applicable. Note that Comparative Example 4 was manufactured as a back substrate. At this time, alumina was used as the filler, and the mixing ratio of glass and filler was 70:30 (% by weight).

It is the schematic of the plasma display panel which shows the use site | part of the low melting glass of this invention as an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front glass plate 2 Back glass plate 3 Sealing material 4 Transparent electrode 5 Bus electrode 6 Transparent dielectric 7 Protective film 8 Address electrode 9 White dielectric 10 Phosphor 11 Bulkhead 12 Ultraviolet 13 Visible light

Claims (9)

The transparent insulating lead-free low-melting-point glass, SiO ₂ 0.1 to 8 _weight%, B 2 _{O 3} 30 to 45, 15 to 35 to ZnO, Li ₂ O 0.1-5 and _R 2 O _{(Na 2 O + K 2 O} , provided that Li ₂ except O) a 0~10, RO (MgO + CaO + SrO + BaO) SiO 2 -B 2 O 3 , characterized in that the containing 10~40 _-ZnO-R 2 _O-RO-based lead-free Low melting glass. The lead-free low-melting glass according to claim 1, wherein Sn converted to an oxide contains 0.1 to 10% by weight. The lead-free low-melting glass according to claim 1 or 2, wherein Cu in terms of oxide contains 0.1 to 5 by weight%. 4. The lead-free low-melting glass according to claim 1, wherein a weight ratio of (B ₂ O ₃ + Li ₂ O + R ₂ O) / SiO ₂ exceeds 8 and is 30 or less. The lead-free low-melting glass according to any one of claims 1 to 4, wherein a weight ratio of Li ₂ O / SiO ₂ is 0.2 or more and 1 or less. The lead-free low-melting glass according to any one of claims 1 to 5, wherein a weight ratio of B ₂ O ₃ / ZnO is 1 or more and 2.5 or less. 7. The linear thermal expansion coefficient at 30 ° C. to 300 ° C. is (65 to 95) × 10 ⁻⁷ / ° C., and the softening point is 500 ° C. or more and 630 ° C. or less. Lead-free low melting glass. A substrate for electronic materials, wherein the lead-free low-melting glass according to any one of claims 1 to 7 is used. A PDP panel using the lead-free low-melting glass according to claim 1.