JP2002293573A - Sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing material for manufacturing glass paste hardly lowering in liquidity of the glass containing SnO even in the case of burning in the air. SOLUTION: The sealing material is characterized in that it contains glass powder containing SnO and powder of reducing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (C)
RT), plasma display (PDP), fluorescent display tube (VFD), field emission display (FED), etc., and sealing materials that can be used as glass paste for sealing IC packages, etc. is there.

[0002]

2. Description of the Related Art In order to hermetically seal a display device such as a cathode ray tube, a plasma display, a fluorescent display tube, and a field emission display, or a ceramic package for accommodating a semiconductor or a quartz oscillator, a low melting point is conventionally used. PbO-B
A sealing material of ₂ O ₃ glass powder is used. This sealing material has a sealing temperature of 430 to 500 ° C. and a coefficient of thermal expansion of about 70 to 100 × 10 ⁻⁷ / ° C.

However, recently, from the viewpoint of environmental problems, a sealing material containing no lead has been demanded.
A sealing material using SnO-containing glass powder such as P ₂ O ₅ has been proposed.

[0004]

In the sealing process of a display device or a package, a sealing material containing glass powder is mixed with a vehicle to form a paste and is applied to a sealing material.
This work is performed by screen printing or a dispenser, but requires an appropriate viscosity to facilitate the coating work. In addition, it is necessary that the organic substance can be dried promptly after the application and that the organic substance is decomposed at the lowest possible temperature in the sealing step. Therefore, a material in which a binder substance (a solid organic substance that is easily decomposed at a low temperature) is dissolved in an organic solvent that is easily volatilized is generally used.

As the organic solvent, terpineol, mentanol, isoamyl acetate, butyl carbitol, butyl carbitol acetate and the like are usually used. On the other hand, as the binder substance, methylcellulose, nitrocellulose, acrylic resin and the like are usually used.

However, when a glass paste produced by kneading the sealing material containing the above-mentioned SnO-containing glass powder and a normal vehicle is fired in the air, SnO
The flow of the contained glass may be reduced, and a problem that sealing may not be performed may occur.

[0007] The object of the present invention is to provide Sn
An object of the present invention is to provide a sealing material that can produce a glass paste in which the flow of O-containing glass is hardly reduced.

[0008]

The sealing material of the present invention comprises S
It is characterized by containing an nO-containing glass powder and a reducing substance powder.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, SnO-P ₂ O ₅
The problem with the system glass powder is that when it is used as a paste, the flow of the glass becomes significantly worse when heated to the sealing temperature.

When a paste is formed only with an organic solvent, this phenomenon is relatively unlikely to occur, and there may be no problem at all. However, pastes containing binders generally lose significant fluidity. Therefore, it has been clarified that the phenomenon of the decrease in fluidity is related to the thermal decomposition of an organic substance, particularly, a binder substance.

The reason why the glass does not flow is not known in detail, but it is presumed that it is probably because SnO in the glass component is oxidized to SnO ₂ on the surface of the glass powder. Once SnO ₂ is formed in the surface layer of the glass particles, even if it is extremely thin, the glass powder loses its fluidity at once.

On the other hand, in the present invention, when the SnO-containing glass powder is used in the form of a paste, in order to prevent a decrease in fluidity caused by the thermal decomposition of the binder substance,
It has been found that it is effective to mix a powder of a reducing substance (a substance having a greater reducing power than glass).

It is believed that the effect of adding the reducing substance is to delay the oxidation of the SnO-containing glass powder by oxidizing the reducing substance itself prior to the oxidation of the glass. Therefore, the properties required for the reducing substance to be added are in a temperature range (250 ° C.
(−450 ° C.), the tendency to take in oxygen
O-P ₂ O greater than the ₅ based glass, and that it does not inhibit the fluidity of the glass. In particular, it is optimal to add SnO and Sb ₂ O ₃ as reducing substances to the above SnO-containing glass powder.

As a preferred example of SnO-P ₂ O ₅ -based glass, SnO 40-70% in mol%, P ₂ O ₅
25~50%, 0~20% ZnO, Li 2 O 0~1
_{0%, Al 2 O 3 0~10} %, glass having a composition of SiO ₂ 0% or SnO 40~65%,, P
_{2 O 5 15~40%, B 2} O 3 0.1~25%, ZnO
0 to 15%, Li ₂ O 0 to 10%, Al ₂ O ₃ 0
10%, and a glass having a composition of SiO ₂ 0 to 5%.

Incidentally, the sealing material may further contain a refractory filler powder for the purpose of adjusting the thermal expansion coefficient, improving mechanical strength, improving fluidity, and the like, in addition to the glass powder. For example, refractory filler powders such as cordierite, zircon, stannic oxide, niobium oxide, zirconium phosphate, willemite, mullite, and NbZr (PO ₄ ) ceramic can be used. Further, the refractory substance powders described above may be used as a mixture of two or more kinds.

The mixing ratio of the glass powder, the reducing substance powder and the refractory substance powder contained in the sealing material is 95.55 to 55% by volume, 0.05 to 5% by volume, and 4 to 4% by volume, respectively.
It is preferably 0% by volume.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

Table 1 shows SnO-containing glass powders (samples a and b) used in the present embodiment.

[0019]

[Table 1]

Each sample was prepared as follows.

First, sample a was prepared as a batch glass raw material such that stannous metaphosphate, stannous oxide,
In sample b, orthophosphoric acid, stannous metaphosphate, zinc phosphate and boric anhydride were mixed and mixed. Thereafter, each was placed in an alumina crucible, covered with a super heat resistant crystallized glass, and then placed at 750 °
For 2 hours. Next, the molten glass was formed into a thin plate by passing it between water-cooled rollers, pulverized by a ball mill, and then passed through a sieve having an aperture of 65 μm to obtain a glass powder having an average particle size of about 7 μm. The properties of the glass of the sample a were such that the transition point was 325.
° C, yield point 350 ° C, coefficient of thermal expansion (30-250 ° C) 1
In 05 × 10- ⁷ / ℃, properties of the glass of the sample b, the transition point 300 ° C., yield point 330 ° C., thermal expansion coefficient of 110 × 10 ^-7
/ ° C.

Table 2 shows an example (sample N) in which the sealing material of the present invention was prepared by mixing each of the above glass powders with a refractory filler powder and adding a reducing substance powder to the glass paste.
o. 1 to 3) and Comparative Examples (Sample Nos. 4 and 5) in which a sealing material containing no reducing substance powder was used as a glass paste.

[0023]

[Table 2]

Each sample was prepared as follows.

First, each of the samples of Examples prepared by adding a reducing substance powder to the prepared sealing materials (glass powder and refractory filler powder) and Comparative Examples not containing the same were mixed with the vehicles shown in Table 2, A well-kneaded mixture was uniformly dispersed to obtain a paste sample. Apply this paste to window glass
Dry at 50 ° C. for 30 minutes, then bake at 480 ° C.
The temperature was raised at a rate of 10 ° C./min to 480 ° C. for 10 minutes.
The thermal expansion coefficient and fluidity of the sample fired in this way were evaluated.

The vehicle used was a solution prepared by dissolving 3% by weight of nitrocellulose in butyl carbitol acetate and a solution prepared by dissolving 5% by weight of an acrylic resin (Elvasite 2045, manufactured by DuPont) in terpineol.

As a result, in Example No. 1 of the present invention. Samples 1 to 3 each have a coefficient of thermal expansion (30 to 250 ° C.) of 7
4.5 × 10- ⁷ /℃,73.0×10- ⁷ /℃,74.0
×× 10- ⁷ / at ° C., flow diameter No. 2 for both samples 1-3
The fluidity was good at 4.0 mm, and the surface had a smooth glossy surface. That is, reducing substances (SnO,
It can be seen that when Sb ₂ O ₃ ) is used as a filler, the glass powder flows well even when a vehicle containing nitrocellulose or a vehicle containing an acrylic resin is used.

On the other hand, No. 1 was prepared for comparison. 4,5
Were not glossy and remained powder.

Next, in order to examine the influence of the vehicle, the same evaluation was performed using the sealing materials shown in Comparative Examples 4 and 5 in Table 2 without mixing with the vehicle. ~ 250 ° C) 75 × 10 ^-7 / ° C and 7
Both were 2 × 10 ⁻⁷ / ° C. and the flow diameter was 24.5 mm, all of which had characteristics suitable for sealing. In the evaluation of the fluidity, each of these fired states had a glossy surface. This indicates that the fluidity was inhibited by the vehicle.

The glass transition point and the yield point were determined by differential thermal analysis (DTA), and the coefficient of thermal expansion was determined by a push-rod type thermal expansion measuring device. The fluidity was evaluated by first placing a sample powder having a weight corresponding to the density of the material in a mold and an outer diameter of 20 mm.
Pressed in the form of a button. Next, place this button on the window glass and set the firing temperature to 480 ° C in an electric furnace at 10 ° C.
The temperature of the button was raised at a rate of / minute and maintained at that temperature for 10 minutes.

The sealing material using the SnO—P ₂ O ₅ glass powder has been described above. However, the method of the present invention uses a glass paste as a glass paste which is easily affected by the vehicle.
The present invention can be applied to all sealing materials using nO-containing glass powder.

[0032]

As described above, the sealing material containing the SnO-containing glass and the reducing substance of the present invention has improved compatibility with vehicles containing a binder such as cellulose or acrylic resin and has poor fluidity. Trouble is unlikely to occur. For this reason, the characteristics of the vehicle can be appropriately changed according to the type of the coating machine and the shape of the sealing material, so that the sealing operation can be performed efficiently. Therefore, the cathode ray tube (C
RT), a plasma display (PDP), a fluorescent display tube (VFD), a field emission display (FED), or the like, or a sealing material used for sealing an IC package.

Continued on the front page F term (reference) 4G062 AA09 BB09 CC01 CC10 DA01 DA02 DA03 DB01 DB02 DB03 DC02 DC03 DC04 DD04 DD05 DE01 DE02 DE03 DE04 EA01 EA02 EA03 EA10 EB01 EC01 ED01 EE01 EF01 EG01 FA01 FB01 F01 FE01 F01 FE01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM08 MM25 MM27 NN40 PP01 PP05 PP06 PP11

Claims (3)

[Claims] 1. A sealing material comprising a SnO-containing glass powder and a reducing substance powder. 2. The method according to claim 1, wherein the reducing substance powder is SnO and / or S
sealing material according to claim 1, characterized in that the b ₂ O _3. 3. The sealing material according to claim 1, wherein the glass powder is a SnO—P ₂ O ₅ glass powder.