JP2001322832A - Sealing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing composition containing no lead component and having properties of low expansion, high fluidity and weather resistance which are necessary to be used for sealing and coating electronic parts. SOLUTION: The composition consists of 40 to 90 vol.% low melting point glass containing, by mol% based on oxides, 45 to 70% SnO, 25 to 50% P2O5, 0 to 15% ZnO, 0 to 6% SiO2, 0 to 7% Al2O3, 0 to 7% SrO and 0.1 to 7% Al2O3+ SrO, and 10 to 60 vol.% zirconium phosphate as inorganic filler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing composition, and more particularly to a sealing composition suitable for sealing an electronic member such as an IC package by a low-temperature heat treatment.

[0002]

2. Description of the Related Art Conventionally, a sealing composition used for sealing an electronic member such as an IC package includes matching, sealing with a substrate by matching insulation, mechanical strength and thermal expansion with the substrate. In this case, excellent fluidity is required, and furthermore, weather resistance that can withstand practical use is required. For this reason, glass compositions containing PbO as a main component have been used.

[0003] Alumina in IC packages, the sealing of the aluminum nitride substrate, a low melting glass is used in the _PbO-B 2 O ₃ -based, dispenser Ya what this was a mixture of organic solvent and a binder to form a paste Apply to the substrate sealing part by screen printing, dry and degreasing 3
Heat sealing was performed at a temperature of 90 ° C to 500 ° C. As these conventional low expansion sealing compositions, for example, JP-A-9-24
A glass containing a high concentration of a lead component as disclosed in Japanese Patent No. 1034 has been used. However, in recent years, there has been a demand for a sealing composition containing no lead component in order to reduce environmental load.

To meet this demand, Japanese Patent Laid-Open No. 9-227154 discloses
In the invention disclosed in the publication, SnO-P₂O ₅Lead-free glass composition
Zircon and kojerai as low expansion inorganic additives
, Aluminum titanate, alumina, mullite, silicon
Mosquito, β-eucryptite, β-spodumene and β-
Contains no lead added from the group consisting of quartz solid solution
New sealing compositions have been developed.

[0005]

However, in the combination of the above-mentioned glass composition and inorganic filler, the thermal expansion coefficient (50 × 1) to be matched with the aluminum nitride base which has recently been used for IC packages is considered.
(0 ⁻⁷ / ° C.) is very difficult to obtain a low expansion sealing composition. Further, even if it is possible to adjust the thermal expansion coefficient so as to satisfy the thermal expansion coefficient by increasing the amount of the low-expansion inorganic additive or the like, a problem arises in that sufficient fluidity for performing sealing at a low temperature cannot be obtained. . Also,
The above glass composition does not have weather resistance that can withstand practical use. If the weathering resistance of the sealing composition is poor, the sealing portion deteriorates over a long period of time, and the airtightness is impaired, which may cause leakage.

The present invention has been made in view of the above circumstances, and is practically necessary for sealing electronic members such as IC packages without containing a lead component in order to reduce environmental load. It is an object of the present invention to provide a sealing composition having both low expansion and high fluidity and high weather resistance.

[0007]

The present invention SUMMARY OF], in order to achieve the above object, focusing on the combination of the zirconium phosphate of the SnO-P ₂ O ₅ based glass and the inorganic filler, the result of extensive studies, practical The present invention has found a sealing composition which has both low expansion and high fluidity, which are required above, and has excellent weather resistance.

That is, according to the present invention, SnO: 45 to 70% and P ₂ O ₅ : 25 to 50 in terms of mol% based on oxide.
_{%, ZnO: 0~15%, SiO} 2: 0~6%, Al 2
O ₃ : 0 to 7%, SrO: 0 to 7%, Al ₂ O ₃ + Sr
O: 40 to 90% by volume of a low melting point glass having 0.1% to 7%, and zirconium phosphate as an inorganic filler 10 to 6%.
0% by volume.

In addition, in terms of mol% on an oxide basis, Sn
_{O: 45~70%, P 2 O} 5: 25~50%, ZnO:
_{0~15%, SiO 2: 0~6%} , Al 2 O 3: 0~7
_{%, SrO: 0~7%, Al} 2 O 3 + SrO: 0.1%
40 to 90% by volume of a low-melting glass having a content of 7 to 7%, and an inorganic filler containing at least zirconium phosphate 10 to 60%.
% By volume.

Examples of the inorganic filler include zircon, cordierite, alumina, mullite, silica, β-eucryptite, β-spodumene, β-quartz solid solution, tin oxide, tin oxide, and titanium oxide in addition to zirconium phosphate. One or more selected from the group consisting of a solid solution, a magnesium phosphate derivative, mullite, alumina, aluminum nitride, silicon nitride, silicon carbide, and niobium oxide can be contained.

Further, it is preferable that the average particle diameter of the zirconium phosphate is not more than 20 μm.

Further, the sealing composition of the present invention is characterized in that the coefficient of thermal expansion is 60 × 10 ⁻⁷ / ° C. or less. In particular, when used for sealing an aluminum nitride substrate, the thermal expansion coefficient is preferably set to 40 to 60 × 10 ⁻⁷ / ° C.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention, by adopting the above structure, does not contain a lead component for reducing environmental load,
A sealing composition having both low expansion and high fluidity, which are practically necessary for sealing an electronic member such as a package, and having high weather resistance can be provided. Hereinafter, preferred embodiments of the low melting point glass and the inorganic filler constituting the sealing composition of the present invention will be described in detail.

SnO is a main component of the low melting point glass, and its content can be 45 to 70 mol%. If the SnO content is less than 45 mol%, the softening point becomes too high, the fluidity of the glass becomes poor, and sealing at 500 ° C. or less cannot be performed. If the content exceeds 70 mol%, vitrification becomes difficult. Preferably 55 to 65
Mol%.

P ₂ O ₅ is also a main component of the low-melting glass, and its content can be 25 to 50 mol%. When the content of P ₂ O ₅ is less than 25 mol%, vitrification becomes difficult, and when the content exceeds 50 mol%, the weather resistance decreases. Preferably 27-38
Mol%.

Although ZnO is not an essential component of the low melting point glass, it has an effect of lowering the thermal expansion coefficient of the glass, and its content can be added up to 15 mol%. When the content of ZnO exceeds 15 mol%, the softening point becomes too high, the fluidity of the glass becomes poor, and the
We cannot seal below. Preferably it is up to 7 mol%.

Although SiO ₂ is not an essential component of the above-mentioned low-melting glass, its inclusion is effective in stabilizing the glass, and can be added up to 6 mol%, preferably up to 3 mol%. If the content of SiO ₂ exceeds 6 mol%, the softening point becomes too high, the fluidity of the glass becomes poor, and sealing at 500 ° C. or lower cannot be performed, which is not preferable.

The inclusion of at least one of Al ₂ O ₃ and SrO has the effect of significantly improving the weather resistance of the glass. Its content is in the range of 0.1 to 7 mol%. The content of at least one of Al ₂ O ₃ and SrO is 0.1%.
If it is less than 1 mol%, there is no weather resistance effect, and if it exceeds 7 mol%, the softening point becomes too high, the fluidity of the glass deteriorates, and sealing at 500 ° C. or lower cannot be performed. Preferably 0.1 to
5 mol%.

The low-melting glass used in the present invention contains, in addition to the above components, BaO, MgO, CaO, CuO, Ni
O, MnO, CoO, Fe ₂ O ₃ , Bi ₂ O ₃ , Sb ₂
One or more of O ₃ , Cr ₂ O ₃ , TiO ₂ , and ZrO ₂ can be contained for the purpose of improving weather resistance and sealing strength. In this case, the content of each component is up to 5 mol%,
The total amount of these components is preferably up to 5 mol%. If the content of these components exceeds 5 mol%, the softening point of the glass increases, and the fluidity of the glass deteriorates.
This is because sealing at a temperature of 00 ° C. or less becomes difficult.

Zirconium phosphate (chemical formula (ZrO) ₂ P ₂ O ₇ ) used as an inorganic filler is 19 × 10 ^−7.
/ C (room temperature to 1000 ° C) with a very low coefficient of thermal expansion. Although this value itself is not particularly remarkable as compared with other inorganic fillers, the effect of lowering the coefficient of thermal expansion without impairing fluidity when forming a sealing composition by mixing with a low-melting glass is effective. Since it is large, it is an essential configuration in the present invention. Therefore, zirconium phosphate is an essential component for performing highly airtight sealing without matching the coefficient of thermal expansion and the thermal expansion coefficient of the sealed material whose expansion has been reduced in recent years, without causing cracking of the sealed material. The content thereof is 10 to 60% by volume based on the total amount of the glass and the inorganic filler. If the content of zirconium phosphate exceeds 60% by volume, the softening point becomes too high, the fluidity of the sealing composition deteriorates, and sealing at 500 ° C. or lower cannot be performed. On the other hand, if the content is less than 10% by volume, it is difficult to sufficiently reduce the expansion, and at the time of sealing, the sealed object is peeled off from the sealed object or the sealed object is cracked. More preferably, the content is 30 to 50% by volume.

Further, the combination of the low melting point glass and zirconium phosphate of the present invention has an advantage that the reactivity of both is low. If the reactivity is low, the inorganic filler and the glass at the time of heat sealing cause an interfacial reaction to deteriorate the fluidity,
Since the inorganic filler does not dissolve into the glass and impair the desired properties, high fluidity and a desired coefficient of thermal expansion can be reliably obtained.

The average particle size of zirconium phosphate added as an inorganic filler is preferably 20 μm or less.
By setting the average particle diameter to 20 μm or less, distortion during firing due to a difference in thermal expansion between the glass and the inorganic filler can be suppressed, and generation of microcracks due to stress can be prevented. More preferably, it is 10 μm or less.

The sealing composition of the present invention has a low melting point glass composition and at least one inorganic filler containing zirconium phosphate so that the calcined product has a thermal expansion coefficient of 40 to 60 × 10 ⁻⁷ / ° C. Is preferable because sealing excellent in airtightness can be performed without impairing the fluidity at the time of sealing. The inorganic filler in the sealing composition of the present invention is effective not only for adjusting the coefficient of thermal expansion but also for improving mechanical strength, weather resistance and water resistance. For this reason, in order to more effectively realize the above characteristics, a plurality of inorganic fillers may be contained in combination in addition to the essential component zirconium phosphate. Such inorganic fillers include zircon, cordierite, alumina, mullite, silica, β-eucryptite, β-spodumene, β-quartz solid solution, tin oxide, tin oxide-titanium oxide solid solution, magnesium phosphate derivative, aluminum nitride , Silicon nitride, silicon carbide, and niobium oxide. When these inorganic fillers are used in addition to zirconium phosphate, it is preferable to use zirconium phosphate in an amount not exceeding 70% by volume in the inorganic filler. If the amount of the inorganic filler other than zirconium phosphate is further increased, the fluidity at the time of sealing is impaired.

The sealing composition of the present invention can be produced by a known method and is not particularly limited. For example, it can be obtained as follows. SnO, P ₂ O ₅ , Zn
A predetermined amount of raw materials for providing O, SiO ₂ , Al ₂ O ₃ , and SrO is blended, heated and melted at a temperature of 800 to 1400 ° C., and poured into a mold to obtain a glass block. When making powder,
Pulverize using a ball mill or the like to obtain a low melting glass powder. Zirconium _{phosphate, ZrOC} 12 · 8H
Mixing _{2 O} and an aqueous solution of phosphoric acid, dried, calcined and synthesized. The obtained zirconium phosphate is pulverized and sieved so as to have an appropriate particle size and used in the present invention. A predetermined amount of the above-mentioned glass powder and the synthesized inorganic filler containing zirconium phosphate are mixed and mixed with a V mixer or the like, whereby the sealing composition of the present invention can be obtained.

[0025]

The present invention will be specifically described below with reference to examples. Table 1 shows examples of the present invention, and Table 2 shows comparative examples. Examples 1 to 6 and Comparative Examples 1 and 2 in the table are examples using a glass powder having a composition within the above range of the low melting point glass according to the present invention, and Comparative Example 1 is zirconium phosphate as an inorganic filler. Comparative Example 2 is an example in which the content ratio of zirconium phosphate is out of the range of the present invention, and Comparative Examples 3 to 5 are examples in which the low-melting glass is out of the above composition range of the present invention. The glass composition in the table is represented by mol%, and the amount of the filler is represented by volume% of the ratio of the inorganic filler to the total amount of the low melting glass and the inorganic filler described in the table.

The low melting point glass in the table is from SnO to SrO
The raw materials were blended so as to have the compositions shown in the above columns, and the blended raw materials were put into a quartz crucible and placed in an electric furnace at 1100 ° C. for 1 hour.
After being heated and melted for a period of time, the mixture was rapidly cooled and formed into a plate shape to obtain a plate-shaped glass block. Next, the glass block was pulverized with a ball mill to obtain glass powder.

On the other hand, zirconium phosphate as the inorganic filler, after mixing an aqueous solution of _ZrOC 12 · 8H _{2 O} and phosphoric acid at a predetermined molar ratio, the precipitate formed is directly dried, and finally calcined at 1400 ° C. Created by doing. The obtained zirconium phosphate was pulverized and sieved so as to have an appropriate particle size, and those having an average particle size shown in the table were selected and used.

The glass powder obtained as described above and an inorganic filler such as zirconium phosphate are homogeneously mixed at the volume ratios shown in the table to prepare a sealing composition. Was measured and evaluated. The measurement method is shown below and the results are shown in the table. Glass transition point (Tg): Measured using a differential thermal analyzer.
Heating was performed at a heating rate of 10 ° C./min, and the first inflection point was read as the glass transition point. The display unit is ° C. Glass softening point (Ts): Measured using a differential thermal analyzer.
The glass was heated at a heating rate of 10 ° C./min, and the third inflection point was read as the glass softening point. The display unit is ° C. Coefficient of thermal expansion: Measured using a differential dilatometer. Heating rate 10
The mixture was heated at a rate of ° C / min, and the average linear expansion coefficient at 30 to 250 ° C was calculated. This value was indicated as α in the unit of (× 10 ⁻⁷ / ° C.). Fluidity: The sample was press-molded into a 12.7 mm cylindrical shape to obtain a measurement sample. This sample was held at 450 ° C. for 10 minutes and fired. The measurement sample flowed by this firing. The diameter of the fired product after flowing was measured to evaluate the fluidity. When used for sealing an IC package, the diameter is preferably 20 mm or more, which is 20 m
m or more was evaluated as good, and less than 20 mm as poor. Weather resistance: The sample was press-molded into a 12.7 mm cylindrical shape,
It was baked while being kept at 50 ° C. for 10 minutes. The obtained fired product was left in a constant temperature / humidity bath at a temperature of 70 ° C. and a humidity of 90% for 200 hours to confirm a change in appearance. Initial Hermeticity: For each sample of the sealing composition, the sealing composition and a vehicle (a solution of nitrocellulose 1.2% by weight dissolved in butyl carbitol acetate) were mixed at a volume ratio of 6: 1. Created a paste. This paste was applied on the surface of an aluminum nitride substrate by screen printing, dried at 110 ° C., and then subjected to a binder removal treatment at 400 ° C. Next, the paste-coated surfaces of the two substrates were overlapped with each other and heated to 430 ° C. to prepare a sealed sample. On this occasion,
The sealing composition of the present invention had good wettability with the aluminum nitride substrate and could form a strong sealing portion. The obtained sealed sample was cut, and the cross section of the sealed portion was observed with a microscope to check for cracks. The description in the table is represented by the number of cracks confirmed among 100 sealed samples prepared under the same conditions. Reliability test: The sealing sample prepared in the initial airtightness test was put into a cooling / heating cycle tester, and subjected to a cooling / heating cycle in which a temperature change of 0 to 100 ° C was repeated 30 times at 1 minute intervals,
The sealed sample was cut, and the cross section of the sealed portion was observed under a microscope to check for cracks. The description in the table is also indicated by the number of cracks confirmed among 100 sealed samples prepared under the same conditions.

[0029]

[Table 1]

[Table 2]

As is clear from the results shown in the table, the samples of Examples 1 to 4 had low expansion (40 to 60 × 10 ⁻⁷ /
C.), high fluidity (450 ° C. × 10 min, diameter after sintering 20 mm or more), and good weather resistance. In particular, in the samples of Examples 1 to 4 in which the average particle size of the inorganic filler was 20 µm or less, no crack was observed in the sealed portion even in the result of the reliability test by the thermal cycle. On the other hand, the samples of Comparative Examples 1 and 2 satisfy the above-mentioned characteristics in terms of the coefficient of thermal expansion, but are not sufficient in terms of fluidity, and the strength of the sealing portion is insufficient, and leakage may occur. Was undeniable. The sample of Comparative Example 3 exhibited a sufficient value in terms of characteristics, but was not preferable in terms of environmental measures because it contained lead. In the samples of Comparative Examples 4 and 5, the glass compositions were out of the range of the present invention, but the weather resistance was poor and the surface was clouded.

[0031]

As described above, since the sealing composition of the present invention does not contain a lead component, the working environment is improved, and it is not necessary to take measures against lead when treating waste containing these materials. Moreover, it has the same low expansion and high fluidity as the sealing composition using lead, and also has good weather resistance, so that it can be used for sealing and coating of electronic components, and performs highly reliable sealing. Can be.

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Claims (5)

[Claims] 1. SnO: 4 in terms of mol% on an oxide basis.
_{5~70%, P 2 O 5:} 25~50%, ZnO: 0~1
_{5%, SiO 2: 0~6%} , Al 2 O 3: 0~7%, S
_{rO: 0~7%, Al 2 O} 3 + SrO: 0.1% ~7%
A sealing composition comprising 40 to 90% by volume of a low-melting glass having the formula: and 10 to 60% by volume of zirconium phosphate as an inorganic filler. 2. SnO: 4 in terms of mol% on an oxide basis.
_{5~70%, P 2 O 5:} 25~50%, ZnO: 0~1
_{5%, SiO 2: 0~6%} , Al 2 O 3: 0~7%, S
_{rO: 0~7%, Al 2 O} 3 + SrO: 0.1% ~7%
40 to 90% by volume of a low-melting glass having: and 10 to 60% by volume of an inorganic filler containing at least zirconium phosphate
A sealing composition comprising: 3. The inorganic filler, in addition to zirconium phosphate, zircon, cordierite, alumina, mullite, silica, β-eucryptite, β-spodumene, β-quartz solid solution, tin oxide, tin oxide-oxidation 3. The composition according to claim 2, further comprising at least one selected from the group consisting of a titanium solid solution, a magnesium phosphate derivative, aluminum nitride, silicon nitride, silicon carbide, and niobium oxide.
The composition for sealing according to the above. 4. The zirconium phosphate having an average particle size of 2
The sealing composition according to any one of claims 1 to 3, wherein the thickness is 0 µm or less. 5. The sealing composition according to claim 1, wherein a coefficient of thermal expansion is 60 × 10 ⁻⁷ / ° C. or less.