JPH08231242A - Low melting point sealing composition - Google Patents

Abstract

PURPOSE: To obtain a low m.p. sealing compsn. giving a sealing material almost free from residual bubbles and not causing blackening even when the SiO2 content of PbO-B2 O3 -Bi2 O3 -SiO2 glass is reduced so as to reduce the m.p. of the glass. CONSTITUTION: This low m.p. sealing compsn. consists of 45-85vol.% glass powder having a compsn. consisting of, by weight, 25-85% PbO, 1-11.2% B2 O3 , 5.1-70% Bi2 O3 , 0.1-20% GeO2 , 0-5% SiO2 , 0-10% Fe2 O3 , 0-10% CuO, 0-15% ZnO, 0-5% TiO2 and 0-9% F2 and 15-55vol.% powdery refractory filler.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a low melting point sealing composition, and more particularly to a low melting point sealing composition suitable for sealing electronic parts such as ceramic packages and display devices. .

[0002]

2. Description of the Related Art Sealing materials used for sealing ceramic packages, display devices, etc. can be sealed at a low temperature so as not to adversely affect ICs, crystal oscillators, etc., and have a coefficient of thermal expansion of ceramics or windows. It is required to be suitable for the plate glass, have good insulating properties so as to prevent signal current from leaking, have high mechanical strength, and have good weather resistance such as water resistance. In addition, especially in the sealing material for the IC package, in addition to these conditions, a soft error occurs when the IC element is irradiated with α-rays. Need to meet.

Conventionally, P that satisfies the above condition is P
_{bO-B 2 O 3 -Bi 2} O 3 low-melting glass powder -SiO ₂ system and, sealing material made by adding a refractory filler powder to these glass powders have been proposed.

[0004]

In recent years, the degree of integration of ICs has tended to become higher and higher, but the heat resistance of the element has decreased accordingly. Therefore, the sealing material is required to have a further lower sealing temperature.

Generally, PbO-B ₂ O ₃ -Bi ₂ O ₃ -S
It is known that the glass of the iO ₂ system has a lower glass transition point and a lower sealing temperature as the content of SiO ₂ is smaller. By the way, the sealing material is mixed with a resin component and an organic solvent to form a paste, which is applied to the sealing portion of a package or the like.
When the content of O ₂ is reduced, the surface of the glass powder is activated, so that when the paste is formed, the binding force between the glass powder and the resin component becomes strong. As a result, it becomes difficult for the resin component to decompose during the heat treatment during sealing, and a phenomenon occurs in which a large amount of bubbles remain in the sealing material or the color changes to black. The bubbles remaining in the sealing material become a factor that deteriorates the sealing strength of the package. Further, it is considered that the blackening of the sealing material occurs because PbO in the glass composition is reduced by the undecomposed material of the resin component to generate Pb metal colloid, which causes deterioration of glass strength and insulation resistance. It is not preferable because it makes it easier.

Under these circumstances, SiO ₂ must be contained in the glass composition in a certain amount or more, and there is a limit to lowering the melting point in the sealing material using this type of glass.

An object of the present invention is to provide a low melting point sealing material in which almost no bubbles remain in the sealing material and blackening does not occur even if the SiO ₂ content in the glass is reduced to lower the melting point. To provide a dressing composition.

[0008]

Means for Solving the Problems As a result of various studies, the present inventors have found that by including GeO ₂ in order to lower the sealing temperature, even if the content of SiO ₂ is small,
It was found that the activation of the glass surface can be suppressed, and is proposed as the present invention.

That is, the low melting point sealing composition of the present invention contains PbO 25 to 85%, B ₂ O ₃ 1 to 11.
2%, Bi ₂ O ₃ 5.1 to 70%, GeO ₂ 0.1
_{~20%, SiO 2 0~5%,} Fe 2 O 3 0~10
%, CuO 0-10%, ZnO 0-15%, TiO
It is characterized by comprising glass powder having a composition of _{20 to} 5% and F _{20 to} 9%.

Further, the low melting point sealing composition of the present invention contains PbO 25 to 85% by weight and B ₂ O _{3 to} 11.2% by weight.
%, Bi ₂ O ₃ 5.1 to 70%, GeO ₂ 0.1
20%, SiO ₂ 0-5%, Fe ₂ O ₃ 0-10
%, CuO 0-10%, ZnO 0-15%, TiO
45 to 85% by volume of glass powder having a composition of _{20 to} 5% and F _{20 to} 9%, and refractory filler powder 15 to 55
And volume%.

[0011]

Since the low melting point sealing composition of the present invention contains GeO ₂ , the stability of the glass powder surface is increased. Therefore, the binding force between the glass powder and the resin component does not increase,
The resin component is easily decomposed by the heat treatment during sealing.

The reason why the composition of the glass powder in the low melting point sealing composition of the present invention is limited as described above will be described below.

The content of PbO is 25 to 85%, preferably 40 to 85%, more preferably 50 to 80%. If the PbO content is less than 40%, the viscosity tends to be high, and if it is less than 25%, the viscosity becomes too high and the glass does not flow sufficiently at low temperatures. On the other hand, if it is more than 85%, the tendency of crystallization becomes strong and the low temperature sealing becomes difficult.

The content of B ₂ O ₃ is 1 to 11.2%, preferably 1.5 to 11.1%, more preferably 2 to 8.
5%. B ₂ O ₃ has the effect of stabilizing the glass. If the content of B ₂ O ₃ is less than 1.5%, the glass tends to be crystallized, and if it is less than 1%, precipitation of crystals becomes remarkable and low temperature sealing becomes impossible. On the other hand, if it exceeds 11.1%, the viscosity of the glass tends to be high,
If it exceeds%, sealing at low temperature becomes difficult.

The content of Bi ₂ O ₃ is 5.1 to 70%, preferably 5.1 to 45%, more preferably 5.1 to 3%.
It is 0%. Bi ₂ O ₃ has the effect of stabilizing the glass without increasing the viscosity and expanding the vitrification range. Bi ₂ O
_{When 3} is less than 5.1%, the vitrification range is narrowed, and particularly in the composition where B ₂ O ₃ is less than 7%, crystallization becomes remarkable and low-temperature sealing becomes difficult. On the other hand, if it is more than 45%, the viscosity of the glass tends to be high, and if it exceeds 70%, the viscosity of the glass becomes too high and the low temperature sealing becomes difficult.

The content of GeO ₂ is 0.1 to 20%, preferably 0.1 to 10%, more preferably 0.1 to 5%.
Is. GeO ₂ is a glass-forming component like SiO _2, and by incorporating this component, a glass having excellent stability can be obtained. Moreover, the same effect can be obtained with a molar content smaller than that of SiO ₂ , the melting point can be lowered, and the stability of the glass powder surface can be increased. If the content of GeO ₂ is less than 0.1%, it has no effect, and if SiO ₂ is reduced to lower the melting point, bubbles will remain in the sealing material after sealing and blackening is likely to occur. Become. Further, the tendency of glass to crystallize becomes strong, and low-temperature sealing becomes difficult. On the other hand, if it exceeds 10%, the viscosity of the glass tends to be high, and if it exceeds 20%, sealing at low temperature becomes impossible.

SiO ₂ is used for the purpose of stabilizing the glass.
%, Preferably up to 2%, more preferably 0.4
It is possible to contain up to%. If SiO ₂ is more than 2%, the glass transition point tends to be high, and if it exceeds 5%, low-temperature sealing cannot be performed. In the present invention, it is desirable to minimize the content of SiO ₂ in order to lower the melting point.

The contents of Fe ₂ O ₃ and CuO are 0 to 1 respectively.
0%, preferably 0 to 7% each, more preferably 0 to 4% each. These components have the effect of stabilizing the glass, but if they are more than 7%, the viscosity of the glass tends to be high, and if they exceed 10%, they do not flow at a low temperature.
The total content of Fe ₂ O ₃ and CuO is preferably 0.2 to 15%, particularly 0.5 to 7%.

The ZnO content is 0 to 15%, preferably 0 to 14%, more preferably 0.1 to 6%. Z
nO has the effect of stabilizing the glass and improving the moisture resistance, but if it exceeds 14%, a crystallization tendency appears, and
If it is more than%, the glass crystallizes and does not flow sufficiently.

The content of TiO ₂ is 0 to 5%, preferably 0 to 2%, more preferably 0 to 1.5%. Ti
O ₂ has the effect of stabilizing the glass, but if it exceeds 2%, the crystallization tendency appears, and if it exceeds 5%, the crystallization tendency becomes remarkable and the fluidity does not flow.

The content of F ₂ is 0 to 9%, preferably 0 to
8%, more preferably 0-5%. F ₂ is Bi ₂
Addition to a composition system containing a large amount of O ₃ has the effect of lowering the glass sticking point and suppressing the tendency of crystallization. If F ₂ is more than 8%, crystallization tends to occur, and if it exceeds 9%, the stability of the glass is impaired, and crystallization becomes remarkable and the glass does not flow.

In addition to the above components, 5% or less of Al ₂
O ₃ , V ₂ O ₅ , AgO, SrO, P ₂ O ₅ , Co ₂ O
₃ , TeO ₂ , and 3% or less of Mo ₂ O ₃ , Rb ₂ O,
Cs ₂ O, Nb ₂ O ₅ , Ta ₂ O ₃ , CeO ₂ , Ni
O, Cr ₂ O ₃ , As ₂ O ₃ , Sb ₂ O ₃ , SnO ₂ ,
A rare earth element such as La ₂ O ₃ can be contained as another component. However, the addition of highly toxic components such as Tl ₂ O and CdO is not environmentally preferable and should be avoided.

The glass having the above composition is amorphous and has good flowability because it is difficult for crystals to precipitate during sealing. Moreover, the glass transition point is as low as 310 ° C. or lower, and the viscosity of the glass is low, so that it is a sealing material suitable for low temperature sealing. Again 30
The coefficient of thermal expansion at ˜200 ° C. is 100 × 10 ⁻⁷ / ° C. or more, and it is possible to seal with a high expansion material compatible with this.

On the other hand, alumina (70 × 10 ⁻⁷ / ° C.), aluminum nitride (45 × 10 ⁻⁷ / ° C.), window glass (85
When sealing a package or display device made of a material that does not conform to the thermal expansion coefficient, such as × 10 ^-7 / ° C), mix refractory filler powder for the purpose of correcting the difference in the thermal expansion coefficient with the adherend. Can be used.

When the refractory filler powder is mixed, the mixing ratio is preferably 45 to 85% by volume of glass powder and 15 to 55% by volume of refractory filler powder. The reason why the ratio of the two is limited in this way is that when the content of the refractory filler powder is less than 15% by volume, the effect is not exhibited, and 55% by volume.
This is because if the amount is larger, the fluidity becomes poor and the sealing becomes difficult.

As the refractory filler powder, lead titanate type ceramics, willemite type ceramics, cordierite, zircon type ceramics, tin oxide solid solution,
Alumina is particularly suitable, and it is preferable to use these alone or in combination. Other than these, titanium oxide, niobium pentoxide, mullite and the like can be used. Note that β-eucryptite has a poor compatibility with glass and significantly reduces the fluidity. Further, it is preferable not to use it because it contains an alkali metal element as a constituent and reduces the insulation resistance.

[0027]

EXAMPLES The low melting point sealing composition of the present invention will be described below based on examples.

Example 1 Table 1 shows SiO ₂ and GeO ₂
Of are intended to illustrate the effect on degradation of the low melting point resin component, sample a is _{PbO-B 2 O 3 -Bi 2} O 3 -
This is an example of SiO ₂ glass, and sample b is sample a to S
iO ₂ and PbO-B ₂ O ₃ except -Bi ₂ O ₃ based glass, sample c shows a low melting point sealing composition of the present invention with the addition of GeO ₂ in 1% sample b, respectively.

[0029]

[Table 1]

The samples in Table 1 were prepared as follows.

The raw material powders are blended so as to have the composition shown in the table,
The mixture was mixed, put in a platinum crucible, melted at 900 ° C. for 1 hour, molded into a thin plate, crushed, and passed through a 350-mesh stainless sieve to obtain a glass powder sample having an average particle diameter of 4 μm.

Next, the glass transition point and the decomposability of the resin component of the obtained glass powder sample were evaluated. For the evaluation of the decomposability of the resin component, 60% by volume of glass powder and 40% by volume of willemite-based ceramic powder were mixed, and the thermal expansion coefficient at 30 to 200 ° C. was calculated as the thermal expansion coefficient of alumina 70 × 10 ⁻⁷ / ° C. 67-73 to fit
The one adjusted to × 10 ^-7 / ° C was used. The results are shown in Table 1.

As is clear from Table 1, sample a had a glass transition point of 307 ° C. and was excellent in decomposability of the resin component. The sample b obtained by removing SiO ₂ from the composition of the sample a is
Although the glass transition point was 292 ° C., which was 15 ° C. lower than that of Sample a, the decomposability of the resin component was poor. On the other hand, the sample b in which GeO ₂ is added has a glass transition point of 296 ° C.
And 11 ° C. were lower than those of the sample a, and the decomposability of the resin component was also excellent.

These facts indicate that Ge ₂ instead of SiO ₂
It is shown that when O ₂ is contained, a melting point can be lowered and a sealing composition having excellent decomposability of the resin component can be obtained.

The glass transition point is measured by a differential thermal analyzer (DT
Determined according to A). The degradability of the resin component was evaluated as follows. First, 5% by weight of an acrylic resin was mixed with a vehicle dissolved in tapineol to form a paste, which had a predetermined thickness on a cerdip (C-DIP) alumina. Printed. After that, it was fired at a temperature higher than the glass transition point by 80 ° C. to decompose the binder, and further fired at the sealing temperature of each glass. Observing the glass film formed in this way, it is not possible when it is blacker than the unbaked product or when it is considered that there are more bubbles in the film of the fracture surface than in the unbaked product. did.

Example 2 Tables 2 to 4 show examples of the low melting point sealing composition made of glass powder according to the present invention.

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

As is clear from Tables 2 to 4, sample A
M has a glass transition point of 195 to 310 ° C. and a thermal expansion coefficient of 102 to 162 × 10 ⁻⁷ / ° C., and all had excellent fluidity and stability.

Each sample in the table was prepared and evaluated in the same manner as in Example 1. The thermal expansion coefficient was measured for the fired product of each sample using a push rod thermal expansion measuring device. As for fluidity, after producing a button with an outer diameter of 20 mm and a height of 5 mm from a sample, heating the button at 380 ° C. for 10 minutes, the button having a diameter of more than 21 mm is good, and the button having a diameter of less than 21 mm is good. I made it impossible. The stability was evaluated by visually observing the surface of the sample after the fluidity test, in which no crystals were observed at all, and when it was observed, it was judged as unsatisfactory.

(Example 3) Tables 5 to 7 are prepared by mixing refractory filler powder with each sample of Tables 2 to 4.
Examples of compositions for sealing C packages (Sample Nos. 1 to 1
15).

[0043]

[Table 5]

[0044]

[Table 6]

[0045]

[Table 7]

As is clear from Tables 5 to 7, sample N
o. Nos. 1 to 15 have a sealing temperature of 410 ° C or less, a package strength of 240 lbf · in or more, and an α ray emission amount of 0.23.
less than count / cm ² · hr, insulation resistance 10 ^9.2 Ω
-It was more than cm, and was excellent in the decomposability of the resin component. The thermal expansion coefficient at 30 to 200 ° C. is
o. 1 to 7 and sample No. 12-15 is 65-75 x 1
0 ⁻⁷ / ° C., sample No. 8-11 is 51-54 × 10 ^-7 /
The temperature was 0 ° C, and values corresponding to alumina (70 x 10 ^-7 / ° C) and aluminum nitride (45 x 10 ^-7 / ° C) were shown.

Tables 8 and 9 show examples (Sample Nos. 16 to 21) of sealing compositions for fluorescent display tubes prepared by mixing the samples of Tables 2 to 4 with refractory filler powder. Is.

[0048]

[Table 8]

[0049]

[Table 9]

As is clear from Tables 8 and 9, sample N
o. In Nos. 16 to 21, the sealing temperature was 400 ° C. or lower, the insulation resistance was 10 ^13.1 Ω · cm or higher, and the resin components were excellent in decomposability. The coefficient of thermal expansion at 30 to 250 ° C was 74 to 76 × 10 ^-7 / ° C, which was a value suitable for that of window glass (85 × 10 ^-7 / ° C).

These facts indicate that the low-melting point sealing composition of the present invention satisfies various conditions required for a sealing material for IC packages and display devices, can be sealed at a low temperature, and decomposes resin components. It has shown that it is excellent in sex.

The sealing temperature is the lowest temperature at which the paste prepared by adding a vehicle to each sample is printed and graded on each package part and then baked at various temperatures to achieve the sealing. I asked. Package strength is 28 leads
It was determined by the torque test of the LSI C-DIP package. In the torque test, a rotational force is applied to the C-DIP base ceramic and the cap ceramic, and the strength at which the sealing material portion breaks is measured with a torque meter.
The α-ray emission amount was measured using a ZnS scintillation counter. The insulation resistance was measured at 150 ° C. by using a mega ohm meter.

The refractory filler powders shown in Tables 4 to 6 were prepared as follows.

Lead titanate-based ceramic powder is PbT
It is a solid solution of CaO in iO ₃ crystal and contains litharge, titanium oxide, and calcium carbonate in a weight percentage of PbO70.
%, TiO ₂ 20%, CaO 10%, and after mixing, calcination is performed at 1100 ° C. for 5 hours, and the calcination product is crushed with alumina balls and passed through a 350-mesh stainless sieve. Then, a powder having an average particle diameter of 4 μm was used.

The willemite-based ceramic powder includes zinc white, optical stone powder, and aluminum oxide in ZnO 7 by weight%.
It was prepared to have a composition of 0%, SiO ₂ 25%, and Al ₂ O ₃ 5%, and after mixing, it was fired at 1440 ° C. for 15 hours, then this fired product was crushed and passed through a 250 mesh stainless sieve. Then, a powder having an average particle diameter of 5 μm was used.

As the cordierite powder, magnesium oxide, aluminum oxide and optical stone powder are used as 2MgO.2Al ₂
Prepare so that the ratio of O ₃ · 5SiO ₂ is, and after mixing,
It was fired at 1400 ° C. for 10 hours, then the fired product was crushed and passed through a 250-mesh stainless sieve.

The zircon ceramic powder was produced as follows. First, natural zircon sand is once decomposed with soda, dissolved in hydrochloric acid, and then repeatedly concentrated and crystallized to obtain zirconium oxychloride having extremely small amounts of U and Th which are α-ray emitting substances, neutralized with an alkali, and then heated. Purified ZrO ₂ was obtained. Furthermore, high-purity silica stone powder and ferric oxide were added to the purified ZrO ₂ in a weight percentage of ZrO ₂ 66%, S
iO ₂ 32% and Fe ₂ O ₃ 2% were blended and mixed, and then calcined at 1400 ° C. for 16 hours. Then, the calcined product was crushed and passed through a 250 mesh stainless sieve. used.

The tin oxide solid solution powder is made of SnO ₂ in weight%.
Tin oxide and manganese dioxide were blended so as to have a composition of 99% and MnO ₂ 1%, mixed and then calcined at 1400 ° C. for 16 hours, and then the calcined product was crushed and passed through a 250-mesh stainless sieve. It was used.

As the alumina powder, a commercially available 350 mesh pass product was used.

[0060]

As described above, the low melting point sealing composition of the present invention satisfies various characteristics required for a sealing material such as a ceramic package or a display device. In particular, the sealing can be performed at a lower temperature than that of the conventional sealing material, and since the phenomenon such as residual bubbles after sealing and the sealing material being discolored black does not occur, the characteristics of the package are not deteriorated. Therefore, it is suitable as a sealing material for electronic parts.

Claims (2)

[Claims] 1. PbO 25-85%, B by weight percentage
₂ O _{3 1 to} 11.2%, Bi ₂ O ₃ 5.1 to 70
%, GeO ₂ 0.1-20%, SiO ₂ 0-5%,
Fe ₂ O ₃ 0-10%, CuO 0-10%, ZnO
A low melting point sealing composition comprising a glass powder having a composition of 0 to 15%, TiO ₂ 0 to 5%, and F ₂ 0 to 9%. 2. PbO 25-85% by weight percentage, B
₂ O _{3 1 to} 11.2%, Bi ₂ O ₃ 5.1 to 70
%, GeO ₂ 0.1-20%, SiO ₂ 0-5%,
Fe ₂ O ₃ 0-10%, CuO 0-10%, ZnO
A low melting point characterized by comprising 45 to 85% by volume of glass powder having a composition of 0 to 15%, 0 to 5% of TiO _{2, and} 0 to 9% of F _{2 and} 15 to 55% by volume of refractory filler powder. Sealing composition.