Sealing material

Abstract

Providing a lead-free glass composition capable of maintaining the form of glass and exhibiting excellent fluidity during firing at a temperature in a low temperature region of higher than 400 °C to 500 °C, and having improved acid resistance SOLUTION: A sealing glass composition comprising, in terms of mol% on an oxides basis, 48 to 72% of TeO2, 8 to 35% of WO3, 2 to 15% of BaO, 1 to 15% of Bi2O3, and 0 to 20% of ZnO.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a sealing material, and more specifically to a sealing material used for sealing electronic devices such as IC packages, bonding metals such as stainless steel together, or for protecting or insulating electrodes, resistors, etc. formed on electronic components, which is substantially lead-free and can be used preferably at low temperatures. [Background technology]

[0002] Sealing materials used to seal IC packages are required to be able to seal at as low a temperature as possible, to have sufficient fluidity when fired for sealing, and to have a thermal expansion coefficient close to that of the packaging material, etc. Sealing materials used to protect electrodes and resistors and for insulating coatings are also required to be able to be fired at a similarly low temperature.

[0003] Generally, PbO-B2O3 and PbO-B2O3-Bi2O3 glass are used as sealing materials that can be used for sealing or coating at low temperatures, and in order to match the thermal expansion coefficient of the target object, such as packaging materials, it has been proposed to add low-expansion ceramics such as lead titanate solid solution fillers to these.

[0004] However, in recent years, the use of lead-containing glass has been avoided due to environmental concerns, and there has been active development of lead-free glass.

[0005] Known lead-free low-melting glasses include phosphate glass, alkali silicate glass, and bismuth-based glass. Among these, bismuth-based glasses have attracted attention due to their ability to be fired at low temperatures and their chemical durability, and many bismuth-based glasses have been developed.

[0006] However, many of the bismuth-based glasses developed to date have high softening points, making their performance insufficient for use as sealing materials. On the other hand, bismuth-based glasses with low softening points have the drawback of being prone to crystallization during firing. Crystallization during the sealing process results in a loss of fluidity, resulting in poor sealing. Furthermore, depending on the amount of filler added, crystallization can also be a trigger. For this reason, the amount of filler that can be added is significantly limited for glasses that contain bismuth and have low softening points. This means that it is difficult to incorporate the necessary amount of filler into the sealing material in order to adjust the thermal expansion coefficient of the sealing layer formed by firing, fluidization, and cooling the sealing material. For example, it is not possible to incorporate enough filler to lower the thermal expansion coefficient of the sealing layer to accommodate objects with low thermal expansion coefficients.

[0007] As a low-melting glass, Patent Document 1 discloses a tellurium oxide-based glass composition containing large amounts of bismuth oxide and tungsten oxide.

[0008] Furthermore, Patent Document 2 discloses a tellurium oxide-based glass composition containing large amounts of bismuth oxide, zinc oxide, and boron oxide, which is used as a sealing material. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2019-031403 [Patent Document 2] Patent No. 6357937 Summary of the Invention [Problem to be solved by the invention]

[0010] The tellurium oxide glass composition disclosed in Patent Document 1 has a problem in that it contains a large amount of alkali metals, and therefore the chemical durability of the glass, particularly its acid resistance, is low.

[0011] On the other hand, the tellurium-based glass composition disclosed in Patent Document 2 mentioned above has the problem that, depending on the specific composition selected, it becomes either an amorphous glass or a crystallized glass, and therefore lacks stability in its glass form.

[0012] An object of the present invention is to provide a lead-free glass composition that can maintain its glass shape and exhibit excellent fluidity during firing, particularly when fired at temperatures in the low temperature range of more than 400°C to 500°C, and that also has improved acid resistance.

[0013] The present inventors have conducted research to solve the above problems. As a result, they have found that by adjusting the glass composition to fall within a specific range, it is possible to obtain a glass composition that does not crystallize during firing at temperatures in the low temperature range of over 400°C to 500°C, exhibits excellent fluidity, can form a sealing layer while maintaining the original glass state (amorphous), and has improved acid resistance, and have completed the present invention. That is, the present invention is as follows. [Means for solving the problem]

[0014] 1. Substantially free of lead oxide In mole percent (oxide equivalent), TeO2: 48-72% WO3: 8-35% BaO: 2-15% Bi2O3: 1~15% ZnO: 0 to 20% characterized in that it comprises Sealing glass composition. 2. The glass composition for sealing according to item 1 above, In mole percent (oxide equivalent), TeO2: 50-70% WO3: 10-30% BaO: 3-10% Bi2O3: 1~10% ZnO: 1 to 15% A composition comprising: 3. The glass composition for sealing according to 1 or 2 above, In mole percent (oxide equivalent), TeO2: 55-65% WO3: 12-28% BaO: 3-8% Bi2O3: 1~5% ZnO: 5 to 13% A composition comprising: 4. The glass composition for sealing according to any one of 1 to 3 above, A composition having a B2O3 content of 0-10%. 5. A glass composition for sealing according to any one of 1 to 4 above, A composition having a molar ratio (TeO2 / Bi2O3) of the TeO2 content to the Bi2O3 content of 5 to 50. 6. The glass composition for sealing according to any one of 1 to 5 above, A composition having a total content of TeO2, WO3, BaO, and Bi2O3 of 79% or more. 7. A sealing material comprising a glass powder made of the sealing glass composition according to any one of 1 to 6 above and a filler powder. [Effects of the Invention]

[0015] The present invention provides a sealing material that is an amorphous glass that is substantially free of lead oxide and that can maintain an amorphous glass state without crystallization when fired at a low temperature range of more than 400°C to 500°C. When applied to the surface of an object and fired, the glass exhibits excellent fluidity and spreads over the surface, and after cooling, becomes acid-resistant glass that is suitable for sealing, adhering, and covering objects. DETAILED DESCRIPTION OF THE INVENTION

[0016] The content of each component of the glass composition for sealing according to the embodiment of the present invention and the reasons for limiting the range of each component will be described below. Note that the content (%) of each component is always expressed in mol %.

[0017] TeO2 is a glass-forming oxide and can be contained as an essential component in the glass composition of the present invention in a range of 48 to 72%. If the TeO2 content is less than 48%, glass may not be formed. Even if a glass is obtained, it may have a high softening point and may not be usable for purposes such as sealing at temperatures above 400°C to 500°C. Furthermore, if the TeO2 content exceeds 72%, crystallization may occur during sealing, resulting in reduced fluidity. Considering factors such as the formability, sealing temperature, and fluidity during sealing of the glass composition of the present invention, the TeO2 content is more preferably 50 to 70%, and even more preferably 55 to 65%.

[0018] WO3 is a component that has been found to enhance the acid resistance of glass in combination with other components of the composition of the present invention, and can be contained as an essential component in the glass composition of the present invention in a range of 8 to 35%. If the WO3 content is less than 5%, the desired acid resistance may not be achieved. If the WO3 content exceeds 35%, glass formation may not be possible. In consideration of the requirements for more reliable glass formability, stability of the glass state, acid resistance, etc. of the composition of the present invention, the WO3 content is more preferably 10 to 30%, even more preferably 12 to 28%, and particularly preferably 15 to 25%.

[0019] BaO is a component that acts to improve the glass-forming ability and stability of the glass state of the composition of the present invention, and can be contained as an essential component in the glass composition of the present invention in the range of 2 to 15%. If the BaO content is less than 2%, the glass composition of the present invention may crystallize and become non-flowable during sealing at temperatures in the low temperature range of over 400°C to 500°C. If the BaO content exceeds 15%, there is a risk that glass formation may not occur. Considering the glass-forming ability of the composition of the present invention and the need to ensure flowability by preventing crystallization, the BaO content is more preferably 3 to 10%, even more preferably 3 to 8%, and particularly preferably 3 to 5%.

[0020] Bi2O3 is an essential component that stabilizes the glass state of the composition of the present invention and is effective in lowering the softening point of the glass. It can be contained in the glass composition of the present invention in a range of 1 to 15%. If the Bi2O3 content is less than 1%, the glass will have a high softening point, resulting in poor fluidity during sealing at temperatures above 400°C to 500°C. If the Bi2O3 content exceeds 15%, the glass state will become unstable, making crystals more likely to precipitate during firing. If crystals precipitate, fluidity will decrease. Considering factors such as the glass formability of the composition of the present invention, the stability of the glass state, and a softening point suitable for sealing at temperatures above 400°C to 500°C, the Bi2O3 content is preferably 1 to 10%, more preferably 1 to 5%, even more preferably 3 to 5%, and particularly preferably 3 to 4.5%.

[0021] ZnO can be contained as an optional component in the glass composition. ZnO is a component that acts to enhance the formability and stability of the glass, and so it is preferable to contain it, but its content is preferably 20% or less. This is because if the ZnO content exceeds 20%, there is a risk that the glass will not be formable. Considering factors such as the formability of the glass composition of the present invention and the stability of the glass state, the ZnO content is more preferably 1 to 15%, even more preferably 5 to 13%, and particularly preferably 10 to 13%.

[0022] B2O3 may also be contained as an optional component in the glass composition of the present invention. While B2O3 is an effective component for improving the stability of the glass state, it also increases the softening point of the glass. Therefore, considering the need to ensure fluidity at the softening point of the glass composition of the present invention, that is, at temperatures in the low temperature range of more than 400°C to 500°C, even when B2O3 is contained, its content is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less, and may be 1% or less, or may be substantially absent, specifically 0.1% or less.

[0023] Li2O, Na2O, and K2O can also be contained as optional components in the glass composition of the present invention. However, since these components lower the softening point of the glass but also reduce the water resistance of the glass, even if they are contained, it is preferable that the total content be 1% or less, and it is even more preferable that they are not substantially contained, specifically 0.1% or less.

[0024] SiO2 and Al2O3 can also be included as optional components in the glass composition of the present invention. However, although these are components that form glass, their inclusion tends to make the resulting glass more susceptible to crystallization. For this reason, the total content of SiO2 and Al2O3 is preferably 1% or less, and more preferably, they are substantially not included, specifically, 0.1% or less.

[0025] Furthermore, V2O5 can be included as an optional component in the glass composition of the present invention. V2O5 is a component that forms glass and lowers the softening point. However, vanadium is a substance generally known to have adverse effects on the human body (vanadium pentoxide is subject to the Ordinance for Prevention of Harm from Specified Chemical Substances under the Industrial Safety and Health Act). Therefore, from the perspective of avoiding exposure concerns, particularly during the glass manufacturing process, its inclusion is preferably 1% or less, more preferably 0.5% or less, and even more preferably substantially absent. Regarding V2O5, "substantially absent" means that raw materials containing V2O5 are not used in the manufacture of the glass composition of the present application. However, its inclusion is permitted to the extent that it is present as an impurity in the raw materials used to manufacture the glass. More specifically, a V2O5 content of 500 ppm or less is considered an impurity.

[0026] In the sealing glass composition of the present invention, the molar ratio (TeO2 / Bi2O3) of the TeO2 content to the Bi2O3 content is preferably 5 to 50. If this molar ratio is less than 5, the composition will have an unstable glass state, and crystals may be more likely to precipitate during firing. If this molar ratio exceeds 50, the composition will have an unstable glass state, and crystals may be more likely to precipitate during firing. In consideration of factors such as glass formability, stability of the glass state, and softening point, the molar ratio (TeO2 / Bi2O3) is more preferably 5 to 35, and even more preferably 10 to 20.

[0027] Furthermore, in order to improve the stability of the glass during production, to prevent crystallization during the firing process at temperatures above 400°C to 500°C, and particularly to adjust the thermal expansion coefficient, so that a filler, described below, can be added while preventing crystallization, the total content of the above-mentioned essential components (TeO2 + WO3 + BaO + Bi2O3) in the glass composition of the present invention is preferably 79% or more, more preferably 83% or more, and even more preferably 87% or more.

[0028] The glass composition of the present invention is substantially free of PbO. Here, "substantially free of PbO" means that raw materials containing any of these constituents are not used in the production of the glass composition of the present application. PbO is acceptable as being substantially free if it is present as an impurity in the raw materials used to prepare the glass. More specifically, a PbO content of 500 ppm or less is considered to be an impurity.

[0029] The glass composition of the present invention is preferably in the form of a powder for convenience in use. There are no particular limitations on the particle size of the glass composition of the present invention in the powder form, but in consideration of flowability during firing, the 50% particle size is preferably 2 to 15 μm, and more preferably 5 to 13 μm.

[0030] In the present invention, the "50% particle size" (D 50) is the particle size at which the cumulative amount, counting from the smallest particle size side, in the volume-based particle size distribution is 50% of the entire sample, and can be measured using a laser analysis / scattering particle size distribution analyzer.

[0031] A ceramic filler can be added to the glass powder made of the glass composition of the present invention for the purpose of adjusting the thermal expansion coefficient when used as a sealing material for an object and improving the strength of the sealing material after solidification. The amount of ceramic filler added can be appropriately adjusted within a range of 40 parts by mass (40% by mass) or less, where the total amount of the ceramic filler and the glass composition is 100 parts by mass.

[0032] Examples of ceramic fillers that can be used include zirconium tungstate phosphate, β-eucryptite, cordierite, zircon, zirconium phosphate, aluminum titanate, mullite, β-spodumene, alumina, celsian, willemite, silica (α-quartz, cristobalite, tridymite), etc. It is desirable to mainly use zirconium tungstate phosphate as the ceramic filler.

[0033] The ceramic filler is usually in the form of a powder, and its 50% particle size is not particularly limited, but is preferably 15 to 25 μm, and more preferably 15 to 20 μm.

[0034] The glass composition of the present invention can be used as a sealing material in the form of a powder as it is, but it can also be used as a suspension such as a slurry or paste in which the powdered glass composition is dispersed in an organic binder and / or an organic solvent.

[0035] The organic binder that can be used with the glass composition of the present invention is not particularly limited, and can be appropriately selected from known binders depending on the specific application of the glass composition of the present invention. Examples include, but are not limited to, cellulose resins such as ethyl cellulose.

[0036] The organic solvent that can be used with the glass composition of the present invention is not particularly limited and can be appropriately selected from known organic solvents depending on, for example, the type and amount of the binder used. Examples include, but are not limited to, alcohols such as methanol, ethanol, and isopropanol, as well as organic solvents such as terpineol (α-terpineol or a mixture of β-terpineol and γ-terpineol with α-terpineol as the main component). These solvents can be used alone or in combination of two or more. [Example]

[0037] The features of the present invention will be described in more detail below with reference to examples, although the scope of the present invention is not limited to these examples.

[0038] (Manufacture of glass, glass powder and glass blocks) As shown in Tables 1 to 3, raw materials were prepared and mixed to obtain the glass compositions of Examples 1 to 12 and Comparative Examples 1 and 2. The resulting mixture was placed in a platinum crucible and melted at a temperature of 800 to 900°C for 1 hour. Next, most of the molten glass was quenched using a twin-roll method to obtain glass flakes, and the remaining portion was poured onto a preheated carbon plate to produce a block. During production, the block was placed in an electric furnace set to a temperature approximately 50°C higher than the expected glass transition point and slowly cooled. The glass flakes were then placed in a pot mill and pulverized to produce glass powder.

[0039] The 50% particle size of the glass powder was measured using a laser diffraction / scattering particle size distribution analyzer (model "MT-3000", manufactured by Nikkiso Co., Ltd.). 50 are shown in Tables 1 to 3.

[0040] For each of the glass compositions of Examples 1 to 12 and Comparative Examples 1 and 2, the glass transition point (Tg), softening point (Ts), and crystallization temperature (Tp) were measured using the glass powder prepared above. The glass powder was also fired and the flow diameter was measured. Furthermore, the thermal expansion coefficient was measured using the glass block. The measurement methods were as follows, and the results are shown in Tables 1 to 3.

[0041] (Physical property evaluation method) 1. Thermal expansion coefficient α of the glass composition The glass block obtained above was cut into a size of approximately 5 × 5 × 15 mm and polished to prepare a sample for measuring the thermal expansion coefficient. Using a TMA measuring device, the sample was heated from room temperature at a rate of 10 °C / min, and the thermal expansion coefficient (×10) was calculated from the thermal expansion curve obtained at two points, 50 °C and 300 °C. -7 / °C) was calculated.

[0042] 2. Glass transition point, softening point, crystallization temperature, whether or not crystallization occurs during firing Approximately 60 to 80 mg of glass powder was filled into a platinum cell, and the glass transition point (°C), softening point (°C), and crystallization temperature (°C) were measured using a DTA measurement device (Rigaku ThermoPlusTG8120) by raising the temperature from room temperature at 20°C / min.

[0043] 3. Regarding the presence or absence of crystallization that hinders flow during firing, the glass powder was fired for 1 hour at a temperature in the range of over 400°C to 500°C, and if no crystals were detected using an X-ray diffraction device, it was judged as good (○), and if crystals were detected, it was judged as bad (×).

[0044] 3. Flow button test 8 g of glass powder was dry-pressed (2 to 4 MPa) into a cylinder with a diameter of 20 mm and fired on a stainless steel substrate for 1 hour at a temperature in the range of over 400°C to 500°C shown in Tables 1 to 3. The maximum diameter of the resulting fired body was measured as the flow diameter.

[0045] 4. Acid resistance test The fired body obtained in the flow button test was cut into a size of 3 x 3 x 10 mm, dried at 100°C for 30 minutes, and then weighed. This was immersed in 1N nitric acid at room temperature for 2 hours, then dried at 100°C for 30 minutes, weighed, and the weight loss rate (%) was calculated. The results are shown in Tables 1 to 3.

[0046] [Table 1]

[0047] [Table 2]

[0048] [Table 3]

[0049] (Adjusting the mixture with filler) Mixed powders of the glass composition powder of Example 4 and ceramic (zirconium tungstate phosphate) powder as a filler were prepared in the ratios shown in Table 4, at 80:20 and 85:15 (glass mass / filler mass), respectively, and used as sealing materials for Examples 13 and 14. Eight grams of this mixed powder was dry-press molded into a 20 mm diameter cylinder (2 to 4 MPa). Eight grams of the glass composition powder of Example 4 alone was also dry-press molded under the same conditions. Each molded body was sintered on a stainless steel substrate at 460°C for 1 hour, and the maximum diameter of the resulting sintered body was measured as the flow diameter. Blocks of approximately 5 × 5 × 15 mm were cut from these sintered bodies and polished to prepare samples for measuring the thermal expansion coefficient. The samples were heated from room temperature at 10°C / min using a TMA measuring device, and the thermal expansion coefficient (×10) was calculated based on two points, 50°C and 300°C. -7 The results are shown in Table 4.

[0050] [Table 4]

[0051] As is clear from the results in Tables 1 to 3, the glass compositions of Examples 1 to 12 have softening temperatures in the range of 406 to 459°C, and indeed exhibit sufficient fluidity even when fired at 490°C. XRD measurements after firing also showed no formation of crystals in the glass compositions of Examples 1 to 12. Furthermore, the results of the acid resistance test confirmed that the glass compositions of Examples 1 to 12 had significantly smaller weight loss rates upon immersion in 1N nitric acid than the glass compositions of Comparative Examples 1 and 2, confirming that they are glasses with high acid resistance.

[0052] Furthermore, as can be seen from Table 4 showing Examples 13 and 14, the thermal expansion coefficient α (50-300°C) of the control, which was formed and fired under the same conditions using only the glass of Example 4, was 138 × 10 -7 / °C, the sealing materials of Examples 13 and 14, which are mixtures of the glass composition of Example 4 and the filler in mass ratios of 80:20 and 85:15, respectively, had a melting point of 56 × 10 -7 / ℃ and 72×10 -7 From this, it was confirmed that the thermal expansion coefficient of the sealing material of the present invention can be greatly adjusted by blending a filler. [Industrial Applicability]

[0053] The glass composition for sealing of the present invention is a sealing material that can be fired at temperatures in the low temperature range of more than 400°C to 500°C. Even when fired at such a low temperature, it has excellent fluidity, so it spreads well over the surface of an object to ensure a tight seal. Furthermore, the glass after cooling and solidifying has excellent acid resistance, so it can be used as a sealing material suitable for sealing electronic components such as IC packages and quartz oscillator packages.

Claims

1. Substantially free of lead oxide In mole percent (oxide equivalent), Tet ２ :48~72% 5 ３ :8~35% BaO: 2 to 15% Yes ２ Oh ３ :1~15% ZnO: 0 to 20% characterized in that it comprises Sealing glass composition.

2. The sealing glass composition according to claim 1, In mole percent (oxide equivalent), Tet ２ :5~70% 5 ３ :11~330% BaO: 3 to 10% Yes ２ Oh ３ :1~10% ZnO: 1 to 15% A composition comprising:

3. The sealing glass composition according to claim 1, In mole percent (oxide equivalent), Tet ２ :55~65% 5 ３ :12~28% BaO: 3 to 8% Yes ２ Oh ３ :1~5% ZnO: 5 to 13% A composition comprising:

4. The sealing glass composition according to claim 1, B ２ O ３ The composition, wherein the content of

5. The sealing glass composition according to claim 1, TeO ２ Content and Bi ２ O ３ The molar ratio of the content of TeO ２ / Bi ２ O ３ ) is 5 to 50.

6. The sealing glass composition according to claim 1, TeO ２ , W.O. ３ , BaO, and Bi ２ O ３ The composition, wherein the total content of

7. A sealing material comprising a glass powder made of the glass composition for sealing according to any one of claims 1 to 6 and a filler powder.

Images