JP2007042376A - Airtight container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid leak failure due to collapse of foam in sealing an airtight vessel with the use of seal glass containing foam. <P>SOLUTION: The airtight vessel of a box shape consisting of a front plate, a rear face plate and side face plates made of glass has beads with a diameter of 50 to 200 μm mixed in seal glass sealing each glass plate. Even in case foam of a maximum outer diameter of 200 μm or so is contained in the seal glass, since an interval between glass plates is decided by the beads in the seal glass, with a size of 50 to 200 μm, the foam of the above size will not grow but to a size of 300 μm at largest, so that a generation rate of leak failure is drastically decreased with consideration of the size of a glass plate of a sealing part of a general airtight vessel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a box-type airtight container configured by sandwiching a side plate between a front plate and a back plate and hermetically sealing them with a seal glass, and in particular to improve airtight defects due to bubbles contained in the seal glass. The present invention relates to an airtight container in which beads are added to seal glass under predetermined conditions.

  In various electronic elements including a display element and the like, a box-shaped airtight container formed by combining glass substrates may be used as an envelope for storing electrodes including a display unit and an internal structure.

  For example, FIG. 3 is a cross-sectional view showing an example of the structure of a fluorescent display tube which is an example of an electronic element having such an airtight container. The hermetic container 10 of the fluorescent display tube includes a translucent front plate 1 made of glass, a back plate 2 made of glass, and four rectangular glass plates combined in advance with a seal glass 11 in a frame shape. The side plate 3 is sandwiched between the outer peripheral portions of the inner surfaces of the front plate 1 and the back plate 2 arranged in parallel at a predetermined interval, and sealed in a box shape with a seal glass 11 It is a thing.

  An anode 14 comprising an anode conductor 12 and a phosphor layer 13 provided thereon is formed on the inner surface of the back plate 2. A control electrode 15 and a filament as an electron source are disposed above the anode 14 in the hermetic container 10. A negative electrode 16 is provided. At the time of driving, the electrons emitted from the cathode 16 strike the anode 14 under the control of the control electrode 15 and cause the phosphor layer 13 to emit light. This light emission can be visually recognized from the outside through the translucent front plate 1.

  Although details of the connecting portion are not shown, the electrodes and the like in the hermetic container 10 are connected to a metal lead 17 that hermetically penetrates the sealed portion of the hermetic container 10 and are electrically connected to the outside of the hermetic container 10. To be derived. In FIG. 3, the inner end portion of the lead 17 that hermetically penetrates the sealing portion is connected to an anode wiring (not shown) connected to the anode conductor 12 formed on the inner surface of the back plate 2.

Further, in Patent Document 1 below, the thickness of the sealing material is set by disposing a large-diameter bead having a diameter of about 300 μm as a kind of spacer member in a sealed portion between the glass plates in such an airtight container. An invention that keeps constant is disclosed.
Japanese Patent Laid-Open No. 2-106856

  The sealing glass used for the hermetic container is generally composed of a low melting point frit glass, a low expansion ceramic (lead titanate, zircon, cordierite, silica, β-eucryptite, etc.) and a coloring pigment as main raw materials. It is made into a paste for convenience during application. The low melting point frit glass included in the sealing glass has a softening point of 350 to 450 ° C., and is heated to a temperature of about 450 to 500 ° C. in assembling the hermetic container.

  The side plate is previously formed by fixing four strip-shaped substrates into a frame shape by applying and baking the sealing glass. Then, the pasted seal glass is printed on the outer peripheral portions of the inner surfaces of the front plate and the rear plate with an appropriate thickness by a screen printing method, and the frame-shaped side plates are sandwiched from both sides and assembled into a box shape. This is fired at a temperature of about 450 to 500 ° C. as described above while being pressed and fixed with an appropriate force, and the thickness of the seal glass between the front plate and the back plate and the side plate is about 250 to 350 μm. A box-shaped airtight container is obtained by managing the production so that

  According to the knowledge obtained by the present inventors through research, the sealing glass generally contains bubbles, or potentially contains gas, and bubbles can be generated by heating at the time of manufacturing an airtight container. However, these bubbles usually have a diameter of 200 μm or less.

  As shown in FIG. 4 (a), in manufacturing the airtight container, first, a seal glass 11 is first applied to the outer peripheral portion on the inner surface side of the front plate 1 with an appropriate thickness, and the side plate 3 assembled in advance in a frame shape. Assemble the upper end of the box as a whole. Then, as shown in FIG. 4B, a force is applied between the front plate 1 and the side plate 3 to pressure-bond both plates 1 and 2, and in this state, heat sealing is performed. In the sealing step involving pressurization and heating, as shown in FIG. 5A, the bubbles 20 (or bubbles generated in the seal glass) contained in the seal glass 11 are shown in FIG. As a result, the projected area on the pressure-bonding surface of the glass plate is larger than the original bubble, and the inside and outside of the airtight container 10 are communicated to eliminate airtightness, or it is not necessary to immediately communicate. Airtight reliability will be greatly reduced.

  In the above sealing step involving pressurization and heating, the particle size of the low expansion ceramic included in the seal glass 11 is 10 μm on average and 30 to 40 μm at the maximum, so the thickness (seal thickness) of the seal glass 11 in the sealed portion Should not be smaller than the maximum diameter of the low expansion ceramics, but actually the surfaces where the glass plates contact each other are not perfectly flat, but have bends and irregularities, so the seal thickness is about 20 to 80 μm. As a result, bubbles having a diameter of 200 μm are crushed to a large area to the extent that the inside and outside of the hermetic container 10 are communicated with each other, causing a leak failure.

  In particular, in the case where the lead 17 that electrically connects the inside and outside of the hermetic container 10 does not penetrate the seal part between the front plate 1 and the side plate 3 of the hermetic container, the seal thickness at the seal part is: This is considered to be determined by the sealing temperature and the clip pressure when the glass plate material is temporarily fixed in combination at the time of sealing.

  For example, when the clip pressure is increased, the seal thickness is thinly crushed to the particle size of the low expansion ceramic contained in the seal glass 11, causing leakage. On the other hand, when the clip pressure is set low in order to prevent a leak failure due to the collapse of bubbles, the lead 17 that electrically connects the sealed portion of the back plate 2 and the side plate 3 between the inside and outside of the airtight container 10 as shown in FIG. In the case of a structure that penetrates, the tip of the lead 17 in the hermetic container 10 is bent to obtain a stable contact with the electrode and is given springiness. The side plate 3 that is not sufficiently clamped is inclined, and a leak may occur at the four corners of the side plate 3 that is fixed in a frame shape in advance.

  The present invention is intended to solve the above-described new technical problem found by the present inventor, and is an airtight container formed by combining glass plates and sealed with seal glass. Even under conditions where bubbles with an outer diameter of about 200 μm are included, there is no leakage failure due to the collapse of the bubbles in the seal glass at the sealed portion, and the sealing function by the seal glass is achieved at the sealed portion. It is an object of the present invention to provide a technical means capable of easily setting an optimum distance between glass plates in order to make the best use.

  The airtight container according to claim 1 is a box-type airtight container in which a side plate is sandwiched between a front plate and a back plate and hermetically sealed with a seal glass, and the diameter of the sealed glass is 50 to 200 μm. It is characterized by mixing of beads.

  An airtight container according to a second aspect is the airtight container according to the first aspect, wherein the seal glass includes frit glass and low-expansion ceramic particles having a smaller diameter than the beads.

  The hermetic container according to claim 3 is the hermetic container according to claim 1 or 2, wherein the beads do not melt at a sealing temperature of the seal glass and are substantially equal in thermal expansion coefficient to the seal glass. The amount added to the sealing glass is 0.05 to 5% by weight.

  The hermetic container described in claim 4 is characterized in that, in the hermetic container according to claim 1, 2, or 3, the seal glass contains bubbles whose diameter is up to 200 μm.

  According to the hermetic container of the present invention described in claim 1 or 4, in the hermetic container in which a glass plate is combined in a box shape and sealed with seal glass, the seal glass contains bubbles having a maximum outer diameter of about 200 μm. Even in such a case, the distance between the glass plates is determined by the beads in the seal glass, and is about 50 to 200 μm. Therefore, even if the bubbles of the above size are crushed, the size is about 300 μm at most. However, if the thickness of the glass plate at the sealing part of a general hermetic container is taken into consideration, the probability of occurrence of a leak failure is significantly reduced. Actually, in the airtight container prepared by adding the beads having the outer diameter, the defective rate of occurrence of leakage due to bubbles was 1/10 or less compared to the case where beads were not added.

  According to the hermetic container of claim 2, in the hermetic container of claim 1, the seal glass includes frit glass and low expansion ceramic particles, but the outer diameter of the beads is smaller than that of the low expansion ceramic particles. Therefore, the collapse of the bubbles contained in the seal glass during the sealing is prevented to the extent that no leak failure occurs.

  According to the hermetic container described in claim 3, in the hermetic container according to claim 1 or 2, the beads do not melt at the time of sealing, and may cause cracks in the seal glass due to a difference in thermal expansion coefficient after solidification. Nor. Further, since the amount of beads added to the seal glass is 0.05% or more by weight, the beads can be present at a density higher than the minimum necessary in the sealing portion, and the seal thickness is constant. Moreover, since the said addition amount is 5% or less by weight ratio, the fluidity | liquidity of seal glass is not inhibited at the time of sealing.

The best mode for carrying out the present invention will be described with reference to FIGS.
This example relates to a box-type airtight container 6 constituted by sandwiching a side plate 3 between a front plate 1 and a back plate 2 and hermetically sealing them with a seal glass 5, It can be widely used as an envelope for housing electrodes and internal structures in various electronic devices. Accordingly, the basic structure of the hermetic container 6 itself in which a glass plate material is assembled into a box shape using the seal glass 5 is substantially the same as that shown in FIG. The description will be omitted with the aid of these.

  And the airtight container 6 of this example adds the bead 7 on the sealing glass 5 on the predetermined conditions, especially in order to improve the airtight defect by the bubble which the sealing glass 5 contains, and restrict | limits the space | interval between glass plate materials in a predetermined range. In addition, control is performed so that the collapse of bubbles existing in the seal glass 5 does not cause inconvenience.

(1) Seal glass 5 The seal glass 5 used for sealing the glass plate in the production of the airtight container 6 of this example is frit glass and low expansion ceramic particles (lead titanate, zircon, cordierite, silica, β- Eucryptite and the like) and color pigments as main raw materials, and are made into a paste for the convenience of application. The low melting point frit glass included in the seal glass 5 has a softening point of 350 to 450 ° C., and is heated to a temperature of about 450 to 500 ° C. in assembling the hermetic container 6.

  The low-expansion ceramic particles have an average particle size of 10 μm, a maximum particle size in the range of approximately 30 to 40 μm, and the seal glass 5 further includes bubbles 20 having an upper limit of 200 μm in diameter. .

  In general, it is desirable that the sealing glass used for sealing is free of bubbles as much as possible. However, if the size (diameter) is 200 μm or less, the sealing glass of a normal hermetic container is used. Based on the inventor's experience, there is no leakage problem. Therefore, if the seal glass 5 used in this example is left as it is, the problem of leakage due to the bubbles 20 should not occur. However, when the seal glass 5 is crushed at the sealing portion of the hermetic container 6, the bubbles 20 are thin and long. As a result, there is a possibility of causing a leakage problem in the sealing portion.

(2) Necessity of beads 7 Therefore, the interval between the glass plates in the sealing portion is set to a certain level or more so as to prevent the bubbles from being crushed (preventing collapse), and the interval between the glass plates is set to a certain level or less. In order to prevent poor sealing due to excessive spacing, beads 7 having a size range suitable for this purpose were added to the sealing glass 5.

  FIG. 1 is a partial enlarged cross-sectional view of an airtight container 6 of the present example, showing a sealing portion by a seal glass 5 provided between an inner peripheral surface of a front plate 1 and an upper end surface of a side plate 3. It is. The seal glass 5 includes beads 7, and the distance between the front plate 1 and the side plate 3 is controlled to be substantially the same as the outer diameter of the beads 7 by the outer diameter of the beads 7. Since the outer diameter of the beads 7 is in the range of 50 μm to 200 μm as described in detail below, even if the maximum diameter of the bubbles 20 potentially contained in the seal glass 5 is 200 μm, the beads 7 are crushed. There is no fear of causing a leak failure in the sealing part.

(3) About the size of the beads 7 The size of the beads 7 was larger than the low expansion ceramic particles included in the seal glass 5. This is because the same degree as the low-expansion ceramic particles does not help to prevent the bubbles 20 included in the seal glass 5 from being crushed. The low-expansion ceramic particles of the seal glass 5 of this example have an average particle size of 10 μm as described above, and the maximum particle size is generally in the range of 30 to 40 μm. Therefore, the lower limit of the particle size of the beads 7 of this example is It must be 50 μm or more.

  Next, when the paste-like seal glass 5 is applied around the inner surface of the front plate 1, a normal printing method is used, but with this method, the thickness of the seal glass 5 can be formed only to about 200 μm at most. Therefore, when the bead 7 has an outer diameter of 200 μm or more, when the front plate 1 and the side plate 3 are pressed with a clip and temporarily fixed at the time of sealing, for example, there is a portion where the seal glass 5 does not rotate in the gap between the glass plates. As a result, there arises a problem that insufficient pressure resistance or leakage occurs in the sealed portion. Therefore, the upper limit of the particle size of the beads 7 in this example needs to be 200 μm or less.

  As described above, the range of the particle diameter of the beads 7 mixed in the seal glass 5 for the purpose as in this example needs to be 50 μm to 200 μm.

  Note that if the particle size of the low expansion ceramic particles included in the seal glass 5 is made a little larger, it can be used as a substitute for the bead 7, so it may be thought that the bead 7 is unnecessary in the first place. As a result of investigation, it has been found that the particle size of the low expansion ceramic particles included in the seal glass 5 cannot be 50 μm or more. If the particle size of the low expansion ceramic particles is 50 μm or more, the seal glass 5 has a different coefficient of thermal expansion at each location, that is, unevenness of the coefficient of thermal expansion occurs, making it impossible to make the coefficient of thermal expansion uniform as a whole. is there.

(4) Material and addition amount of beads 7 The beads 7 are preferably made of a material that does not melt at the sealing temperature of the seal glass 5 and has a thermal expansion coefficient substantially equal to that of the seal glass 5. For this purpose, usable materials include soda glass, ceramics, or other high melting point glass.

  The amount of beads 7 added to the seal glass 5 varies depending on the particle size of the beads 7 and the composition (specific gravity) of the beads 7, but is preferably about 0.1 to 3% by weight in the case of glass beads 7 having an outer diameter of 100 μm, for example. In the case of 0.1% by weight or less, the amount of the beads 7 present in the sealing portion is too small, or even if it exists, it falls into the shaving of the glass end face and the function of controlling the distance cannot be exerted, and the distance between the glass plates is limited. It may become impossible to control the value of the period and cause the seal thickness to vary. Further, when the content is 3% by weight or more, the fluidity of the glass is deteriorated, the molten seal glass 5 is difficult to move, and there is a possibility that a leak failure occurs in the sealing portion.

  However, if the specific gravity is the same for the beads 7 having a large specific gravity, the actual number of particles is reduced, so the problem of fluidity of the seal glass 5 at the time of sealing is reduced. The amount can be up to 5%.

  However, if the specific gravity is the same for beads 7 having a small specific gravity, the actual number of particles increases, so the problem of fluidity of the seal glass 5 at the time of sealing increases. The amount is preferably up to 0.05%.

  FIG. 2 shows the amount of beads 7 added to the sealing glass 5 (% by weight), and the flow diameter (the amount of the sealing glass 5 in a fluid state) of the sealing glass 5 having a predetermined weight including each amount of beads 7 at 480 ° C. It is a graph which shows the relationship with the relative value of (outer diameter). Assuming that the flow diameter in the case where the beads 7 are not included (when the value on the horizontal axis is 0) is 100%, the more the beads 7 are contained in the seal glass 5, the worse the fluidity and the smaller the flow diameter. When the addition amount of the beads 7 is 5% by weight with respect to the seal glass 5, the flow diameter is reduced to 90%. However, in practice, this is an allowable range for the decrease in fluidity due to the addition of the beads 7.

  As described above, the addition amount of the beads 7 mixed into the seal glass 5 for the purpose as in the present example needs to be in the range of 0.05 to 5% by weight ratio with respect to the seal glass 5, and certain conditions are satisfied. If it is 0.1 to 3% of range below, a more preferable result will be obtained.

(5) Application position It is not preferable to apply the leak prevention structure with the seal glass 5 containing the beads 7 in this example to a sealing portion where the metal lead 17 or the like penetrates airtightly. If the sealing glass 5 containing the beads 7 as in this example is applied to the sealing portion where the leads 17 are present, if the beads 7 are interposed between the conductors to be connected to the leads 17 and the leads 17, contact This is because a problem of failure occurs. Therefore, it is preferable that the leak prevention structure with the seal glass 5 containing the beads 7 having the structure as in this example is applied only to a sealing portion where the lead (external connection terminal) 17 does not penetrate to obtain an effect.

(6) Effect In the airtight container 6 of this example using the sealing glass 5 to which 0.5% of glass beads 7 having an average particle diameter of 100 μm are added, the incidence of bubbles 20 having an outer diameter of 0.2 mm or more in the sealed portion is Further, the occurrence rate is reduced to 1/10 or less of the same rate in the case of the airtight container 6 using the conventional seal glass 5 not including the beads 7, and a highly reliable airtight container can be provided.

  Since the thickness of the sealing glass 5 at the sealing portion is controlled by the outer diameter of the bead 7, it can be precisely controlled to a predetermined constant thickness, and cracks and the like caused by strain due to concentration of sealing stress Can be mitigated.

  It becomes possible to set a high pressure (clip pressure) for fixing the glass plates to each other at the time of sealing, and the occurrence of leakage due to the inclination of the side plate 3 and poor contact of leads is reduced.

It is a partial expanded sectional view of the airtight container which concerns on embodiment of this invention. Relationship between addition amount (% by weight) of beads with respect to seal glass and relative value of flow diameter (outer diameter of seal glass in fluid state) of seal glass having a predetermined weight including each addition amount of beads at 480 ° C. It is a graph which shows. It is sectional drawing which shows an example of the structure of an airtight container. It is a partial expanded sectional view which shows the subject in the conventional airtight container. It is a partial expanded sectional view which shows the subject in the conventional airtight container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Front plate 2 ... Back plate 3 ... Side plate 5 ... Seal glass 6 ... Airtight container 7 ... Bead 17 ... Lead 20 ... Air bubble

Claims (4)

In a box-type airtight container formed by sandwiching a side plate between a front plate and a back plate and hermetically sealing with a seal glass,
An airtight container, wherein beads having a diameter of 50 to 200 μm are mixed in the sealing glass. The hermetic container according to claim 1, wherein the seal glass includes frit glass and low-expansion ceramic particles having a smaller diameter than the beads. The beads are made of a material that does not melt at the sealing temperature of the seal glass and has a thermal expansion coefficient substantially equivalent to that of the seal glass, and the addition amount to the seal glass is 0.05 to 5% by weight. The airtight container according to claim 1 or 2, wherein The hermetic container according to claim 1, 2 or 3, wherein the seal glass includes bubbles having a diameter of up to 200 µm.

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