JP5202134B2 - Lead-free low-temperature glass frit, lead-free low-temperature glass frit paste material, image display device and IC ceramic package using the same - Google Patents

Description

  The present invention relates to a lead-free low-temperature glass frit that can be used for sealing, coating and the like at a low temperature and includes a lead-free low-melting glass and a lead-free filler, a lead-free low-temperature glass frit paste material using the same, an image display device, and an IC ceramic package .

  A low-temperature glass frit is used in an image display device or the like in which a front plate and a back plate are hermetically sealed, such as a plasma display panel (PDP). The low-temperature glass frit comprises a low-melting glass that softens and flows at a low temperature of 500 ° C. or lower and a filler for reducing the thermal expansion of the glass. Conventionally, glass mainly composed of lead oxide as such a low-melting glass and lead titanate as a filler have been used.

  In recent years, the use of materials containing lead has been avoided due to environmental and safety regulations. As a lead-free low-temperature glass frit, Patent Document 1 is a glass mainly composed of bismuth oxide, Patent Document 2 is a glass composition mainly composed of tin oxide, and Patent Documents 3 and 4 are glasses composed mainly of vanadium oxide. Has been proposed. As the lead-free filler, powders of quartz glass, cordierite, β-eucryptite, zinc silicate, zircon, alumina and the like are combined.

  In general, a portion sealed or coated with a low-temperature glass frit is in a state where a filler is uniformly dispersed in a low-melting glass. Patent Documents 5 and 6 have been proposed as low-temperature glass frit in which fillers are uniformly dispersed.

  Conventional lead-free low-temperature glass frit has been considered not to contain harmful lead and to control thermal expansion, but what is the material design considering the specific gravity and particle size of lead-free filler for lead-free low melting glass? It wasn't. In addition, the dispersion state of the lead-free filler in the portion hermetically sealed or coated with the conventional lead-free low-temperature glass frit is aimed to be uniformly dispersed in the low melting point glass. It was not clear.

  Conventional lead-free low-temperature glass frit contains lead-free filler in order to match thermal expansion with the material to be sealed and the material to be coated, and the lead-free filler is uniformly dispersed in the sealing part and covering part. In general. In order to efficiently reduce the thermal expansion by containing a lead-free filler, it is better to increase the particle size of the lead-free filler as long as the sealing portion and the covering portion are not damaged. According to this, since the content of the lead-free filler can be reduced, hermetic sealing and coating can be performed at a low temperature without impairing the fluidity of the lead-free low-temperature glass frit. However, when the particle size of the lead-free filler is increased, there arises a problem that the sealed portion is scratched and the unevenness of the covering portion is increased.

  On the other hand, when the particle size of the lead-free filler is made small, it is necessary to increase the content thereof, the fluidity of the lead-free low-temperature glass frit is impaired, and there is a problem that it is difficult to hermetically seal and coat at low temperatures.

Japanese Patent Laid-Open No. 10-139478 JP-A-7-69672 JP 2004-250276 A JP 2006-342044 A JP 2000-103642 A JP 59-35040 A

  Accordingly, an object of the present invention is to provide a lead-free low-temperature glass frit in which the specific gravity, particle size, and content of the lead-free filler with respect to the lead-free low-melting glass are taken into account, and the dispersion state of the lead-free filler in the sealing part or the covering part is appropriately controlled. An object of the present invention is to provide a lead-free low-temperature glass frit paste material, an image display device, and an IC ceramic package using the above.

That is, lead-free low-temperature glass frit of the present invention, sealing at 500 ° C. or less, in the lead-free low-temperature glass frit coating, the lead-free low-temperature glass frit, a lead-free low-melting-point glass, smaller lead-free than the specific gravity of the lead-free low-melting-point glass The lead and the lead-free filler larger than the specific gravity of the lead-free low-melting glass are dispersed, and the average particle size of the lead-free filler smaller than the specific gravity of the lead-free low-melting glass is larger than the specific gravity of the lead-free low-melting glass. It is characterized by being larger than the average particle size .

  The lead-free low-temperature glass frit of the present invention has a lead-free low-melting glass content of 60 to 80% by volume and a total content of lead-free fillers of 20 to 40% by volume, which is smaller than the specific gravity of the lead-free low-melting glass. The average particle size of the lead-free filler, which is 20 μm or more larger than the specific gravity of the low-melting glass, is 10 μm or less. Furthermore, it is preferable that the content of the lead-free filler smaller than the specific gravity of the lead-free low-melting glass is equal to or larger in volume ratio than the content of the lead-free filler larger than the specific gravity of the lead-free low-melting glass. It is desirable that the content of the filler is 10 to 30% by volume, the content of the lead-free filler larger than the specific gravity of the lead-free low-melting glass is 5 to 20% by volume, and the remainder is the lead-free low-melting glass.

  The lead-free low-temperature glass frit of the present invention is characterized in that the specific gravity of the lead-free low-melting glass is 3.0 to 4.0. This lead-free low-melting glass is a phosphate glass, and preferably contains vanadium as a main component.

  Moreover, the lead-free low-temperature glass frit paste material of this invention is characterized by including said lead-free low-temperature glass frit, a resin binder, and a solvent.

  Further, the image display device of the present invention is an image display device in which a front plate and a back plate are opposed to each other and an outer peripheral portion is hermetically sealed with a low-temperature glass frit, wherein the low-temperature glass frit is the lead-free low-temperature glass frit described above. It is characterized by being.

  The IC ceramic package of the present invention is an IC ceramic package in which a ceramic substrate on which wiring and an IC chip are mounted is hermetically sealed with a ceramic lid, and the low temperature glass frit is hermetically sealed with a low temperature glass frit. Or a lead-free low-temperature glass frit described in any one of items 10 to 10 above.

  According to the present invention, environmental load can be reduced and low-temperature glass sealing or coating at 500 ° C. or lower can be performed, and the sealed portion is not scratched or unevenness of the coated portion is not increased. A highly practical lead-free low-temperature glass frit, a lead-free low-temperature glass frit paste material using the same, an image display device, and an IC ceramic package can be provided.

  The present invention will be described in further detail.

  In a lead-free low-temperature glass frit that is sealed and coated at 500 ° C. or less, the lead-free low-temperature glass frit includes a lead-free low-melting glass, a lead-free filler larger than the specific gravity of the lead-free low-melting glass, and a small lead-free filler. The lead-free filler dispersion state in the part hermetically sealed or coated by the frit is uniformly dispersed in the lead-free low-melting glass, so that the sealed part is scratched or the unevenness of the coated part becomes large. Disappear. However, if the lead-free filler is composed only of lead-free fillers that are larger than the specific gravity of the lead-free low-melting glass, the lead-free filler tends to sink in the low-melting glass and there are no surface irregularities, but there are cracks on the surface. The problem that it is easy to occur occurs. On the other hand, if the lead-free filler is composed only of lead-free fillers smaller than the specific gravity of the lead-free low-melting glass, the lead-free filler tends to float in the low-melting glass and there is no surface cracking. The problem that the unevenness is large occurs. In addition, cracks may occur at the bottom. Furthermore, the sealed portion may be scratched by the unevenness of the surface. In addition, since there are many lead-free fillers and few lead-free low-melting glasses on the surface, good adhesion to the sealed portion may not be obtained.

  Furthermore, the lead-free filler larger than the specific gravity of the lead-free low-melting glass and the small lead-free filler have different average particle sizes, and preferably the average particle size of the lead-free filler larger than the specific gravity of the lead-free low-melting glass is smaller than the specific gravity of the lead-free low-melting glass. By making it smaller than the average particle size of the lead-free filler, the lead-free filler can be dispersed more uniformly in the lead-free low-melting glass, and a more reliable hermetic seal and coating can be achieved. The preferable average particle diameter of the lead-free filler was 10 μm or less for the lead-free filler larger than the specific gravity of the lead-free low-melting glass, and 20 μm or more for the lead-free filler smaller than the specific gravity of the low-melting glass.

  Moreover, it is preferable that content of lead-free low melting glass is 60 to 80% by volume, and total content of lead-free filler is 20 to 40% by volume. Content of lead-free low melting glass is less than 60% by volume, When the total content exceeds 40% by volume, the fluidity during firing deteriorates, the amount of heat shrinkage and surface irregularities increase, and it is difficult to obtain good adhesive strength. On the other hand, if the content of the lead-free low-melting glass exceeds 80% by volume and the total content of the lead-free filler is less than 20% by volume, it is difficult to control the thermal expansion and fluidity of the lead-free low-temperature glass frit. is there. Furthermore, it is preferable that the content of the lead-free filler larger than the specific gravity of the lead-free low-melting glass is smaller by volume than the content of the lead-free filler smaller than the specific gravity of the lead-free low-melting glass. It is desirable that the content of the lead-free filler is 5 to 20% by volume, the specific gravity of the lead-free low-melting glass is less than the specific gravity of 15 to 30% by volume, and the balance is the lead-free low-melting glass. If the content of the lead-free filler having a large specific gravity is greater than the content of the lead-free filler having a small specific gravity, the amount of heat shrinkage and the surface unevenness will increase.

  Conventional low melting glass tends to become heavier as the glass softens and flows at a lower temperature. On the other hand, the lead-free filler having a small thermal expansion tends to be lighter in specific gravity than the low melting point glass. That is, the lower the glass frit that can be sealed and coated at a lower temperature, the greater the difference in specific gravity between the low-melting glass and the filler, and it becomes difficult to disperse uniformly. In the prior art, if the filler cannot be uniformly dispersed, the frit cannot be uniformly reduced in thermal expansion, and the sealing part and the sealing material are damaged. In order to improve this, in the present invention, the specific gravity of the filler was controlled with respect to the specific gravity of the low-melting glass. Furthermore, the point which cannot be covered with specific gravity was adjusted with the particle size of the filler.

  The lead-free low-temperature glass frit of the present invention is generally applied as a paste form. The paste is prepared by adding a resin binder and a solvent to a predetermined amount of lead-free low-melting glass powder and the above two lead-free filler powders and mixing them uniformly. Usually, this paste is applied to a predetermined location by a dispenser method or a printing method, and baked after drying. In the case of sealing, it is combined with the material to be sealed and further heat treated to obtain a highly airtight glass sealing part.

  The lead-free low-temperature glass frit of the present invention can obtain a high-yield and highly reliable sealing part or covering part in order to appropriately control the specific gravity, particle size, content, etc. of the lead-free low-melting glass or lead-free filler. it can. Therefore, the present invention can be effectively applied to low-temperature airtight sealing and sealing of image display devices such as plasma displays, IC ceramic packages, bulb lamps and fluorescent tube lighting devices.

  In the image display device, the front plate and the back plate are opposed to each other, and the outer peripheral portion is hermetically sealed with the lead-free low-temperature glass frit of the present invention. In an IC ceramic package, a ceramic substrate on which wiring and IC chips are mounted is hermetically sealed with a ceramic lid on the outer peripheral portion with the lead-free low-temperature glass frit of the present invention.

  Hereinafter, the present invention will be specifically described based on embodiments.

[First Embodiment]
Table 1 shows the lead-free low-melting glass examined.

  G1-3 is a phosphoric acid low melting glass mainly composed of vanadium oxide, G4 is a phosphoric acid low melting glass mainly composed of tin oxide, and G5 is a boric acid low melting glass mainly composed of bismuth oxide. is there. The specific gravity of the glass was measured by the Archimedes method. The thermal expansion coefficient of the glass was calculated in the range of room temperature to 300 ° C. using a sample processed to 4 × 4 × 20 mm, measuring the thermal expansion curve with a thermal dilatometer. The standard sample was converted using quartz glass. The softening point of the glass was subjected to differential thermal analysis (DTA) to obtain the second endothermic peak temperature of the DTA curve. The low melting point glass of Table 1 was used after being pulverized so that the average particle diameter was in the range of 5 to 10 μm.

  As shown in Table 2, as lead-free fillers, F11 to 13 quartz glass having different average particle diameters, F21 to 25 cordierite, F31 to 33 zirconium phosphate, F41 to 43 alumina, F51 to 53 Niobium oxide was used.

  A lead-free low-temperature glass frit paste was prepared using the lead-free low melting glass powder of Table 1, the lead-free filler powder of Table 2, and a resin binder and solvent. Ethyl cellulose or nitrocellulose was used as the resin binder, and butyl carbitol acetate was used as the solvent. As shown in FIG. 1, the lead-free low-temperature glass frit paste 1 was applied on the glass substrate 2 with a line width of 5.0 ± 0.2 mm and a length of 90 to 95 mm by a dispenser method. A panel glass for plasma display of 100 × 50 × 1.8 mm was used for the glass substrate. The glass substrate 2 coated with the lead-free low-temperature glass frit paste 1 was dried at 150 ° C. for 30 minutes and then baked at 460 ° C. for 1 hour. The firing atmosphere was in the air or in nitrogen according to each lead-free low melting glass. Only phosphoric acid-based low melting point glass G4 containing tin oxide as a main component, which cannot be fired in the air, was used in nitrogen.

  The thermal contraction rate, maximum surface roughness (Ry), cracks on the surface, and cracks on the glass substrate were evaluated. The thermal shrinkage was measured from the amount of shrinkage with respect to a line width of 5 mm. Each of the three lines was measured at one central portion, and the average value was defined as the heat shrinkage rate. The maximum surface roughness (Ry) was measured in a longitudinal direction of 20 mm with a straight needle method roughness meter. Similarly, each of the three lines was measured at one central portion, and the average value was defined as the maximum surface roughness (Ry). Cracks on the frit surface were observed with an optical microscope or laser microscope from the surface. The cracks in the glass substrate were determined by visual observation from the back surface and observation with an optical microscope. Further, the dispersion state of the lead-free filler in the lead-free low-melting glass was evaluated by cutting and polishing the glass substrate 2 on which the lead-free low-temperature glass frit paste 1 was applied, dried and baked, and observing its cross section by SEM.

  Table 3 shows the prepared lead-free low-temperature glass frit paste, firing conditions, and evaluation results after firing.

  In Example 9 and Comparative Example 6, since phosphoric acid glass G4 containing tin oxide as a main component was used, firing in the atmosphere was difficult, and firing was performed in nitrogen. Moreover, since it baked in nitrogen, nitrocellulose was used as a resin binder. In other examples and comparative examples, low melting point glass that can be fired in the air was used, so that ethyl cellulose was used as the resin binder, and the firing atmosphere was air.

  Examples 1 to 3 are phosphoric acid-based low-melting glass G1 mainly composed of vanadium oxide as a lead-free low-melting glass, quartz glasses F11 to 13 having a specific gravity smaller than that of G1 glass as lead-free filler, and alumina F41 to 43 having a large specific gravity. Using. Examples 4 and 5 are phosphoric acid-based low-melting glass G2 mainly composed of vanadium oxide as a lead-free low-melting glass, cordierite F21, 24 having a specific gravity smaller than that of G2 glass as a lead-free filler, and zirconium phosphate F31 having a large specific gravity. 33 was used. Examples 6-8 are phosphoric acid-based low-melting glass G3 mainly composed of vanadium oxide as a lead-free low-melting glass, and cordierite F22, 23, 25 having a specific gravity smaller than that of G3 glass as a lead-free filler, and niobium oxide F51 having a large specific gravity. ~ 53 was used. In Example 9, as a lead-free low-melting glass, a phosphoric acid-based low-melting glass G4 mainly composed of tin oxide was used, and as a lead-free filler, quartz glass F13 having a specific gravity smaller than that of G4 glass and zirconium phosphate F32 having a large specific gravity were used. . In all the examples, good results were obtained in all of the heat shrinkage ratio, maximum surface roughness, surface cracks, and substrate cracks after firing, and lead-free fillers smaller than the specific gravity of lead-free low melting glass and large lead-free fillers. It was found effective to use both. As shown in FIG. 2, the filler dispersion state after firing was such that lead-free filler 5 smaller than the specific gravity of lead-free low-melting glass 4 and lead-free filler 6 were uniformly dispersed in lead-free low-temperature glass frit 3. This is thought to have given good results.

  On the other hand, in Comparative Examples 1 to 9, the specific gravity of the lead-free filler was either smaller or larger than the specific gravity of the lead-free low-melting glass, and good results were not obtained. Comparative Examples 1 to 3 and 6 to 9 were cases where the specific gravity of the lead-free filler was smaller than the specific gravity of the lead-free low-melting glass, and cracks occurred in the glass substrate. Moreover, the maximum surface roughness was very large compared with Examples 1-9. Furthermore, the heat shrinkage rate is also larger than in Examples 1-9. When the cross section is observed by SEM, as shown in FIG. 3, the lead-free filler 5 smaller than the specific gravity of the lead-free low-melting glass 4 is large at the top of the lead-free low-temperature glass frit 3 and is small at the bottom. It is thought that the roughness of the surface has increased. In Comparative Examples 4 and 5, when the specific gravity of the lead-free filler was larger than the specific gravity of the lead-free low-melting glass, cracks occurred on the surface portion of the frit. When the cross section is observed by SEM, as shown in FIG. 4, the lead-free filler 6 larger than the specific gravity of the lead-free low-melting glass 4 is large at the bottom of the lead-free low-temperature glass frit 3 and decreases at the top. It is thought that it occurred.

  Further, in Examples 1 to 9, Examples 3, 5 and 7 to 9 had a tendency that both the heat shrinkage rate and the maximum surface roughness were small, and further favorable results were obtained. In Examples 3, 5, 7 to 9, as shown in FIG. 2, the average particle size of the lead-free filler 5 smaller than the specific gravity of the lead-free low-melting glass 4 is larger than the specific gravity of the lead-free low-melting glass. It is larger than the particle size. This is considered to have the effect of reducing both the heat shrinkage rate and the maximum surface roughness.

  Furthermore, since the specific gravity of the lead-free low-melting glasses G1 to G4 in Table 1 is much smaller than that of G5, there is an advantage that it is easy to select a lead-free filler having a large specific gravity and a lead-free filler having a small specific gravity based on that. In the case of G5 glass, a lead-free filler having a very large specific gravity and a specific gravity smaller than that of the glass is easy to select, whereas a lead-free filler having a large specific gravity is difficult to select. Considering the specific gravity of the lead-free filler, the specific gravity of the lead-free low-melting glass is preferably in the range of 3.0 to 4.0. As the lead-free low-melting glass in this range, phosphoric acid-based low-melting glass such as G1-4 glass is effective. More desirably, phosphoric acid-based low-melting-point glass mainly composed of vanadium oxide such as G1 to 3 glass is particularly effective because it can be fired in the air.

[Second Embodiment]
Next, each content was examined using the lead-free low melting point glass of Table 1 and the lead-free filler of Table 2. As the lead-free low-melting glass, phosphoric acid-based low-melting glass G1 containing vanadium oxide as a main component, quartz glass F13 having a specific gravity smaller than that of G1 glass and alumina F42 having a large specific gravity as lead-free fillers were used. The average particle size (20 μm) of the lead-free filler F13 is larger than the average particle size (10 μm) of F42, and the result of Example 1 is reflected. A lead-free low-temperature glass frit paste was prepared using ethyl cellulose as a resin binder and butyl carbitol acetate as a solvent. This paste was applied, dried and fired in the same manner as in Example 1. Firing was held at 430 ° C. in the air for 1 hour. Evaluation after firing was also performed according to Example 1.

  Table 4 shows the prepared lead-free low-temperature glass frit and the evaluation results.

  In Examples 10 to 19, good results were obtained in all the states of thermal shrinkage, maximum surface roughness, surface cracks, substrate cracks and lead-free filler after firing, and the inclusion of lead-free low-melting glass. It was found that the composition range is preferably such that the amount is 60 to 80% by volume and the total content of lead-free filler is 20 to 40% by volume. On the other hand, in Comparative Examples 10 and 11 outside this composition range, good results were not obtained. In Comparative Example 10, the content of lead-free low-melting glass is as high as 90% by volume with respect to Examples 10 to 19, while the total content of lead-free filler is as low as 10% by volume. Although the thickness Ry was a good result, the effect of reducing the thermal expansion by the lead-free filler was insufficient, and cracks occurred on the surface of the frit and the glass substrate. In Comparative Example 11, the content of lead-free low-melting glass is as small as 50% by volume compared to Examples 10 to 19, while the total content of lead-free filler is as large as 50% by volume. Although cracks did not occur, the heat shrinkage rate and the maximum surface roughness Ry became very large. In addition, if too much lead-free filler is added, there is a possibility that good fluidity cannot be obtained and adhesiveness becomes poor.

  In Examples 10 to 19, Examples 10, 11, 13 to 15, 17 and 18 have a tendency that both the thermal contraction rate and the maximum surface roughness are smaller than those of Examples 12, 16 and 19, Even better results were obtained. In Examples 10, 11, 13 to 15, 17, and 18, the volume ratio of the lead-free filler F13 smaller than the specific gravity of the lead-free low-melting glass G1 is larger than the content of the lead-free filler F42 larger than the specific gravity of the lead-free low-melting glass G1. It is considered that this was effective in heat shrinkage and maximum surface roughness. Further, preferable composition ranges are 10 to 30% by volume of the lead-free filler F13 smaller than the specific gravity of the lead-free low-melting glass G1, 5 to 20% by volume of the lead-free filler F42 larger than the specific gravity of the lead-free low-melting glass G1, and the balance being the lead-free low melting point. It was glass G1.

[Third Embodiment]
In this example, the particle size of the lead-free filler was examined using the lead-free low-melting glass shown in Table 1 and the lead-free filler shown in Table 2. As the lead-free low-melting glass, phosphoric acid-based low-melting glass G3 mainly composed of vanadium oxide, cordierite F21-25 having a specific gravity smaller than that of G3 glass and niobium oxide F51-54 having a large specific gravity as lead-free fillers were used. Reflecting the results of Example 2 above, the content of the lead-free low-melting glass was 70% by volume, and the total content of the lead-free filler was 30% by volume. Further, the content of lead-free filler (cordierite) smaller than the specific gravity of the lead-free low-melting glass was made constant at 20% by volume, and the content of lead-free filler (niobium oxide) larger than the specific gravity of the lead-free low-melting glass was made constant at 10% by volume. A lead-free low-temperature glass frit paste was prepared using ethyl cellulose as a resin binder and butyl carbitol acetate as a solvent. This paste was applied, dried and fired in the same manner as in Examples 1 and 2. Firing was held at 480 ° C. in the air for 1 hour. Evaluation after firing was also performed according to Examples 1 and 2.

  First, lead-free filler F51 (average particle size 1 μm) larger than the specific gravity of lead-free low melting glass G3 is fixed, and lead-free fillers F21 to F25 (average particle size 5 to 45 μm) smaller than the specific gravity of lead-free low melting glass G3 are examined. Then, the thermal shrinkage rate and the maximum surface roughness Ry of the lead-free low-temperature glass frit were examined. The result is shown in FIG. The average particle size of the lead-free filler having a specific gravity smaller than that of the lead-free low-melting glass increased, and both the heat shrinkage rate and the maximum surface roughness decreased, and good results were obtained when the average particle size was 20 μm or more. When the cross section was observed with an SEM, the lead-free filler was uniformly dispersed in the lead-free low-temperature glass frit as shown in FIG.

  Next, lead-free fillers F24 (average particle size 30 μm) smaller than the specific gravity of the lead-free low-melting glass G3 are fixed, and lead-free fillers F51 to F54 (average particle size 1 to 20 μm) larger than the specific gravity of the lead-free low-melting glass G3 are examined. Then, the thermal shrinkage rate and the maximum surface roughness Ry of the lead-free low-temperature glass frit were examined. The result is shown in FIG. As the average particle size of the lead-free filler having a specific gravity larger than that of the lead-free low melting point glass increases, both the heat shrinkage rate and the maximum surface roughness increase, and good results are obtained when the average particle size is 10 μm or less. When the cross section was observed with an SEM, the lead-free filler was uniformly dispersed in the lead-free low-temperature glass frit as shown in FIG.

  From the above, the particle size of the lead-free filler uniformly dispersed in the lead-free low-temperature glass frit is smaller than the specific gravity of the lead-free low-melting glass, the average particle size of the lead-free filler is 20 μm or more, and larger than the specific gravity of the lead-free low-melting glass It is preferable that the average particle diameter of is 10 micrometers or less.

[Fourth Embodiment]
In this embodiment, an example in which the lead-free low-temperature glass frit of the present invention is applied to a plasma display panel will be described. An outline of a cross-sectional view of the plasma display panel is shown in FIG.

  In the plasma display panel, the front plate 10 and the back plate 11 are arranged to face each other with a gap of 100 to 150 μm, and the gap between the substrates is maintained by the partition walls 12. The peripheral portions of the front plate 10 and the back plate 11 are hermetically sealed with a sealing frit 13, and the inside of the panel is filled with a rare gas. The minute spaces (cells 14) partitioned by the partition walls 12 are filled with red, green, and blue phosphors 15, 16, and 17, respectively, and one pixel is composed of three color cells. Each pixel emits light of each color according to the signal.

  The front plate 10 and the back plate 11 are provided with electrodes regularly arranged on a glass substrate. The display electrode 18 on the front plate 10 and the address electrode 19 on the back plate 11 are paired, and a voltage of 100 to 200 V is selectively applied according to the display signal between them, and ultraviolet rays 20 are generated by the discharge between the electrodes to generate red. , Green and blue phosphors 15, 16, and 17 are caused to emit light to display image information. The display electrodes 18 and the address electrodes 19 are covered with dielectric layers 22 and 23 in order to protect these electrodes and control wall charges during discharge.

In the back plate 11, the partition wall 12 is provided on the dielectric layer 23 of the address electrode 19 in order to form the cell 14. The partition 12 is a stripe-like or box-like structure.
Further, in order to improve contrast, a black matrix (black band) 21 may be formed between display electrodes of adjacent cells.

  As the display electrode 18 and the address electrode 19, a silver thick film wiring is generally used. The display electrodes 18, the address electrodes 19, and the black matrix 21 can be formed by a sputtering method, but a printing method is advantageous for reducing the cost. The dielectric layers 22 and 23 are generally formed by a printing method.

  In the front plate 10, after forming the display electrodes 18 and the black matrix 21 so as to be orthogonal to the address electrodes 19 of the back plate 11, a dielectric layer 22 is formed on the entire surface. A protective layer 24 is formed on the dielectric layer 22 in order to protect the display electrodes 18 and the like from discharge. In general, a MgO vapor deposition film is used for the protective layer 24. The back plate 11 is provided with a partition wall 12 on the address electrode 19 and the dielectric layer 23. The partition wall made of a glass structure is made of a structural material containing at least a glass composition and a filler, and is composed of a fired body obtained by sintering the structural material. The partition wall 12 forms a partition wall 12 by volatilizing the sheet by attaching a partition wall volatile sheet with a groove cut into the partition wall, pouring a partition wall paste into the groove, and baking it at 500 to 600 ° C. in the atmosphere. can do. Moreover, the partition wall paste is formed by applying partition wall paste on the entire surface by printing, masking after drying, removing unnecessary portions by sandblasting or chemical etching, and baking at 500 to 600 ° C. in the atmosphere. You can also. The cells 14 separated by the barrier ribs 12 are filled with pastes of phosphors 15, 16, and 17 of the respective colors, and baked at 450 to 500 ° C. in the atmosphere to form the phosphors 15, 16, and 17, respectively. To do.

  Usually, the front plate 10 and the back plate 11 produced separately are opposed to each other, accurately aligned, and sandwiched and fixed by a number of clips to exhaust and gas replace the peripheral portion of each panel at 420 to 500 ° C. and glass. Seal. The sealing frit 13 is formed in advance on the peripheral edge of either the front plate 10 or the back plate 11 by a dispenser method or a printing method. Generally, the sealing frit 13 is formed on the back plate 11. In general, the sealing frit 13 is preliminarily fired in advance simultaneously with the firing of the phosphors 15, 16, and 17. By adopting this method, it is possible to remarkably reduce bubbles in the glass sealing portion, and a highly airtight, that is, highly reliable glass sealing portion is obtained. In the glass sealing, the gas inside the cell 14 is exhausted while heating, and a rare gas is enclosed, whereby the panel is completed.

  In order to light the completed panel, a voltage is applied at a portion where the display electrode 18 and the address electrode 19 intersect to discharge the rare gas in the cell 14 to obtain a plasma state. Then, using the ultraviolet rays 20 generated when the rare gas in the cell 14 returns from the plasma state to the original state, the phosphors 15, 16 and 17 are caused to emit light, the panel is turned on, and image information is displayed. . When each color is lit, address discharge is performed between the display electrode 18 and the address electrode 19 of the cell 14 to be lit, and wall charges are accumulated in the cell. Next, by applying a certain voltage to the display electrode pair, display discharge occurs only in the cells in which wall charges are accumulated by address discharge, and ultraviolet light 20 is generated to cause the phosphor to emit light, thereby displaying image information. Is done.

  Using the lead-free low-temperature glass frit shown in Table 5 as a sealing frit, the plasma display panel shown in FIG. 7 was produced.

The lead-free low-temperature glass frit shown in Table 5 is selected from the lead-free low-melting glass G2 shown in Table 1 and the lead-free fillers F12, 13, 21, 23, 32, 42, 43, and 51 shown in Table 2 above. The lead-free low-temperature glass frit paste was used in the same manner as in Examples 1 to 3. G2 glass is a phosphoric acid-based low melting glass mainly composed of vanadium oxide. The thermal expansion coefficient of the sealing frit was set to (65 to 70) × 10 ⁻⁷ / ° C. by adjusting the mixing ratio of the lead-free low melting point glass and the lead-free filler. The glass substrates used for the front plate 10 and the back plate 11 are made of high strain point glass having a thermal expansion coefficient of 80 to 85 × 10 ⁻⁷ / ° C., so that the sealing frit 13 is subjected to compressive stress. I made it. The lead-free low-temperature glass frit of Examples 20 and 21 in Table 5 reflects the results of Examples 1 to 3 described above, and has a lead-free filler F13 or 23 smaller than the specific gravity of the lead-free low-melting glass G2 and a large lead-free filler F42 or 51. Using. As the lead-free low-temperature glass frit of Comparative Example 12, lead-free fillers F12 and F21 having a specific gravity smaller than the specific gravity of the lead-free low-melting glass G2 were used. Moreover, the lead-free low-temperature glass frit of the comparative example 13 used the lead-free fillers F32 and 43 larger than the specific gravity of the lead-free low melting glass G2.

  The lead-free low-temperature glass frit paste shown in Table 5 was applied to the peripheral portion of the back plate 11 with a line width of 3.5 mm by a dispenser method. After drying at 150 ° C. for 30 minutes, calcination was performed in the air at 480 ° C. for 30 minutes. The thermal contraction rate, the maximum surface roughness Ry, and the surface crack of the lead-free low-temperature glass frit after calcination were evaluated. After these evaluations, the back plate 11 and the front plate 10 were accurately opposed, fixed with clips, heated to 450 ° C. while evacuating, held for 3 hours, filled with a rare gas, and cooled. The sealing evaluation was based on the possibility of sealing, airtightness, and scratches on the front plate. Moreover, the lighting test was also implemented for the produced panel.

  Table 6 shows the results of panel mounting evaluation of the lead-free low-temperature glass frit shown in Table 5.

  In Examples 20 and 21, the glass could be hermetically sealed without any problems in the preliminary firing step and the sealing step. There was no problem in the panel lighting test. The panel was disassembled after the panel lighting test, and the cross section of the glass sealing part was observed with an SEM. As a representative example, the cross-sectional SEM observation result of Example 20 is shown in FIG. Although some bubbles 25 were observed, it was found that the confidentiality of the glass sealing part was high. Further, in the sealing frit 13, that is, the lead-free low-temperature glass frit 3, the lead-free filler 5 (F13) having a specific gravity smaller than that of the lead-free low-melting glass 4 (G2) and the lead-free filler 6 (F42) having a larger specific gravity are uniformly diffused. This makes it possible to make highly reliable airtight clothing.

  On the other hand, in Comparative Example 12, the heat shrinkage rate and the maximum surface roughness of the lead-free low-temperature glass frit were large in the pre-baking process, and the front plate was scratched in the sealing process. As a result of lighting the panel, scratches on the front plate caused disconnection of the display electrodes. In Comparative Example 13, the thermal shrinkage ratio and the maximum surface roughness of the lead-free low-temperature glass frit were good in the pre-baking step, but cracks were generated on the frit surface. When this was brought into the sealing process, when the front plate and the back plate were combined and fixed with clips, cracks on the surface of the frit developed and the frit was peeled off. For this reason, sealing could not be performed, and sealing evaluation and panel evaluation could not be performed.

  As described above, the lead-free low-temperature glass frit of the present invention can be effectively applied to low-temperature glass sealing of plasma display panels.

[Fifth Embodiment]
In this embodiment, an example in which the lead-free low-temperature glass frit of the present invention is applied to an IC ceramic package will be described. An outline of a sectional view of the IC ceramic package is shown in FIG.

  In the IC ceramic package, the peripheral portion is hermetically sealed with a sealing frit 13 between a laminated ceramic substrate 28 on which a metallization 26 and terminals 27 are formed and a ceramic cap 29. Usually, for sealing glass of an IC ceramic package, a sealing frit 13 is applied to the peripheral portion of the ceramic cap 29 by a printing method. At that time, the sealing frit is used as a paste. After the ceramic cap 29 coated with the sealing frit 13 is dried, it is temporarily fired at about 450 ° C. in the atmosphere. Using a dedicated fixing jig, the ceramic cap 29 on which the sealing frit 13 is formed and the laminated ceramic substrate 28 are opposed to each other, and a load is applied and the fixing jig is glass-sealed at 430 ° C. or less in an inert atmosphere.

  In this example, an IC package using alumina ceramics was studied. As the lead-free low-temperature glass frit used for the sealing frit 13, the lead-free low-melting glass G1 in Table 1 and the lead-free fillers F13 and 52 in Table 2 were applied. The composition is 80% by volume of G1 glass, which is a phosphate-based low-melting glass mainly composed of vanadium oxide, 12% by volume of F13 filler, which is a lead-free filler having a specific gravity smaller than that of G1 glass, and has a specific gravity higher than that of G1 glass. F52 filler, which is a large lead-free filler, was 8% by volume. A lead-free low-temperature glass frit paste was prepared using ethyl cellulose as the resin binder and butyl carbitol acetate as the solvent. This paste was applied to an alumina ceramic cap 29 by a printing method and dried at 150 ° C. for 30 minutes. Thereafter, the ceramic cap 29 was temporarily fired at 450 ° C. for 30 minutes in the atmosphere. Subsequently, the alumina ceramic cap 29 formed with the sealing frit 13 and the alumina laminated ceramic substrate 28 are opposed to each other by a fixed jig, and a heat treatment is performed at 420 ° C. for 30 minutes in an argon gas under a load. Then, 10 IC ceramic packages were produced. There was no problem with any IC ceramic package, and it was possible to seal the glass airtightly. In addition, an operation test was conducted to confirm that there was no problem. The IC ceramic package of the operation test was disassembled, and the cross section of the glass sealing part was observed with an SEM. The cross-sectional SEM observation result is shown in FIG. Although some bubbles 25 were observed, it was found that the confidentiality of the glass sealing part was high. Further, in the sealing frit 13, that is, the lead-free low-temperature glass frit 3, the lead-free filler 5 (F 13) having a specific gravity smaller than that of the lead-free low-melting glass 4 (G 1) and the lead-free filler 6 (F 52) having a higher specific gravity are uniformly diffused. This makes it possible to make highly reliable airtight clothing.

  As described above, the lead-free low-temperature glass frit of the present invention can be effectively applied to low-temperature glass sealing of IC ceramic packages.

  The lead-free low-temperature glass frit of the present invention can be widely applied to various electronic devices other than plasma displays and IC ceramic packages.

It is a figure which shows the evaluation sample of a lead-free low temperature glass frit. It is sectional drawing which shows the lead-free low temperature glass frit containing the lead-free filler whose specific gravity is smaller than lead-free low melting glass, and the lead-free filler with large specific gravity. It is sectional drawing which shows the lead-free low temperature glass frit containing the lead-free filler whose specific gravity is smaller than lead-free low melting glass. It is sectional drawing which shows the lead-free low temperature glass frit containing the lead-free filler whose specific gravity is larger than lead-free low melting glass. It is a graph which shows the relationship between the average particle diameter of the lead-free filler whose specific gravity is smaller than lead-free low melting glass, a thermal contraction rate, and the maximum surface roughness. It is a graph which shows the relationship between the average particle diameter of the lead-free filler whose specific gravity is larger than a lead-free low melting glass, a thermal contraction rate, and the maximum surface roughness. It is sectional drawing which shows the structure of a typical plasma display panel. It is a cross-sectional SEM photograph of the glass sealing part of the plasma display panel produced in the Example. It is sectional drawing which shows the structure of a typical IC ceramic package. It is a cross-sectional SEM photograph of the glass sealing part of the IC ceramic package produced in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lead-free low-temperature glass frit paste 2 Glass substrate 3 Lead-free low-temperature glass frit 4 Lead-free low melting glass 5 Lead-free filler smaller specific gravity than lead-free low-melting glass 6 Lead-free filler larger specific gravity than lead-free low-melting glass 7 Substrate crack 8 Surface crack 10 Front plate 11 Back plate 12 Bulkhead 13 Sealing frit 14 Cells 15, 16, 17 Phosphor 18 Display electrode 19 Address electrode 20 Ultraviolet 21 Black matrix 22, 23 Dielectric layer 24 Protective layer 25 Air bubble 26 Metallized 27 Terminal 28 Multilayer ceramic substrate 29 Ceramics cap

Claims (11)

In lead-free low-temperature glass frit that seals and coats below 500 ° C,
The lead-free low-temperature glass frit, a lead-free low-melting-point glass,
A lead-free filler smaller than the specific gravity of the lead-free low-melting glass;
Lead-free filler greater than the specific gravity of the lead-free low-melting glass is dispersed,
The lead-free low- temperature glass frit characterized in that an average particle diameter of the lead-free filler smaller than a specific gravity of the lead-free low melting glass is larger than an average particle diameter of the lead-free filler larger than a specific gravity of the lead-free low melting glass . Wherein a content of the lead-free low-melting-point glass is 60 to 80% by volume, lead-free low-temperature glass frit according to claim 1, the total content of said lead-free filler, characterized in that 20 to 40% by volume. The average particle size of the lead-free filler smaller than the specific gravity of the lead-free low-melting glass is 20 µm or more, and the average particle size of the lead-free filler larger than the specific gravity of the lead-free low-melting glass is 10 µm or less. The lead-free low-temperature glass frit described in 1 or 2 . The content of the specific gravity is smaller than the lead-free filler of the lead-free low melting glass of claim 1, wherein the equivalent or more by volume than the content of a specific gravity greater than the lead-free filler of the lead-free low-melting-point glass The lead-free low temperature glass frit of any one of Claims. The content of the lead-free filler smaller than the specific gravity of the lead-free low-melting glass is 10 to 30% by volume, the content of the lead-free filler larger than the specific gravity of the lead-free low-melting glass is 5 to 20% by volume, and the balance is The lead-free low-temperature glass frit according to any one of claims 1 to 4 , wherein the lead-free low-melting glass is used. The lead-free low-temperature glass frit according to any one of claims 1 to 5 , wherein the specific gravity of the lead-free low-melting glass is 3.0 to 4.0. The lead-free low-temperature glass frit according to claim 6 , wherein the lead-free low-melting glass is a phosphate glass. The lead-free low-temperature glass frit according to claim 7 , wherein the phosphate glass includes vanadium oxide. Lead-free low-temperature glass frit according to any one of claims 1 to 8 ,
A resin binder,
A lead-free low-temperature glass frit paste material comprising a solvent. In the image display device in which the front plate and the back plate are opposed to each other and the outer peripheral portion is hermetically sealed with a low-temperature glass frit,
9. The image display device according to claim 1, wherein the low-temperature glass frit is the lead-free low-temperature glass frit according to any one of claims 1 to 8 . In an IC ceramics package in which a ceramic substrate with wiring and IC chip mounted is hermetically sealed with a ceramic lid on the outer periphery with a low-temperature glass frit.
An IC ceramic package, wherein the low-temperature glass frit is the lead-free low-temperature glass frit according to any one of claims 1 to 8 .

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