JPS6054252B2 - Low expansion sealing composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing composition that has low expansion and a low melting point and is mainly used for sealing IC packages and the like.

The sealing glass conventionally used for sealing IC packages, display tubes, and furnace seals for cathode ray tubes is made of low-expansion metals such as Kovar and N.

O. A12O is used because it is necessary to seal a ceramic substrate whose main component is A12O. It was necessary to have a coefficient of linear thermal expansion smaller than that of Kovar and larger than that of Kovar, a transition point of 400° C. or less, and good electrical insulation properties. However, all the low melting point glasses conventionally used for this purpose have the disadvantage of having a large coefficient of linear thermal expansion, and therefore various fillers such as those described below have not been added in order to reduce the coefficient of linear thermal expansion. One example is zircon, which has good acid resistance, but has a linear thermal expansion coefficient of approximately 45 x 10-''/°C, so it is necessary to add a large amount to reduce the linear thermal expansion coefficient to the required value. Another example, lead titanate, has a linear thermal expansion coefficient of -60 x 10-''/°C, which is a negative expansion, and although the fluidity of the glass is good, the dielectric constant The disadvantage was that it was expensive.

β-Eucryptite, which is another example, has the smallest linear thermal expansion coefficient of -120×10-'/°C, so it has the effect of reducing the linear thermal expansion coefficient with a small amount of addition, and has a low dielectric constant, but it has a low dielectric constant, but it has the lowest linear thermal expansion coefficient of -120 x 10-'/℃. When added to the glass, Li20 dissolves in the glass and impairs the fluidity of the glass, and Li20 contained in β-eucryptite impairs the electrical insulation properties of the glass. The present invention has been made to solve these drawbacks, and is intended to solve these problems.
The eucryptite particles have a transition point of 250 to 400°C and 30% or less (weight is omitted below) and the remaining 70% or more.
The linear thermal expansion coefficient between ~2500C is 80~130×10
A low expansion sealing composition which is a low melting point glass of −″/°C,
The low melting point glass is PbOI■, B, 0.

By coating the surface of β-eucryptite powder particles added to glass with tin oxide, the β-eucryptite powder particles can be added to glass. Therefore, it is possible to avoid melting into the glass, reducing the expansion rate of the glass without impairing its fluidity, and also avoiding deterioration of its insulation properties. In this case, the tin oxide film is stable within the glass. Moreover, the reason why tin oxide was selected for the surface skin of the β-eucryptite powder is that it hardly reacts with glass and β-eucryptite, has a melting point of 112rc, which is sufficiently higher than the operating temperature of the low expansion sealing composition of the present invention, This is also because it has various properties such as easily forming a thin film on the surface of β-eucryptite. This will be explained in detail below using examples.

Example 1 Each raw material of L1203, A1203, and SiO2 was
2O:Al2O3:SiO2 was blended so that the molecular ratio was 1:1:2, kept in an alumina crucible at a temperature of 1400'C for 3 hours, melted, cooled, and made into a frit.
It was heat-treated again at a temperature of 0° C. for 5 hours and crystallized to create a β-eucryptite crystallized product.

This was ground in a ball mill to obtain β-eucryptite powder with an average particle size of about 20 μm. Next, after mixing the above β-eucryptite powder and tin octylate, the temperature was raised at 20 (generations)/hour and heat treated at 600C for 3 times to form a tin oxide film on the surface of the β-eucryptite powder. I let it happen. The thickness is shown in Table 1. Next, these β-eucryptite powders having a surface film of tin oxide were mixed with 78% PbO and B2.
What is the total amount with Oml6%? % and the remainder is SlO2 and 3% and A
] 203 with 3% low melting point glass (transition point 305°C, coefficient of linear thermal expansion 113 x 10-7/°C), heated until it has fluidity, and after cooling, the coefficient of linear thermal expansion, fluidity , electrical insulation properties, and thermal shock resistance were measured and are shown in Table 1.

Note *1 Observation and measurement using a scanning electron microscope.

*2 The measurement method is a cylindrical plate with a diameter of 12TgL and a height of 7.7m.
A molded product was made, and 6 pieces of powder were kept at a firing temperature of 500°C, and the flow diameter was measured after cooling. *3 The resistance between the leads of the 3rd dip is 1 between leads 3A and 3B in Figure 1.
After 1 minute of applying 00V DC voltage, measure the resistance between the leads using a super megohmmeter.

*4 After tin plating the leads, a DC voltage of 10V is applied between the leads in an atmosphere with a temperature of 65°C and humidity of 95%! Apply 2
The resistance between the leads was measured after 0C@.

In addition to Table 1, there were NO.
2~NO. 4 is an abnormal N but does not have a tin oxide film.
O. Comparative product No. 1 in which the thickness of the tin oxide film exceeds 0.8μ. 5, the glass flow deteriorated.

As can be seen from Table 1, by providing a tin oxide film on β-eucryptite, the coefficient of linear thermal expansion is reduced, fluidity is improved, insulation resistance does not deteriorate even under high temperature and high humidity, and thermal shock resistance is achieved. It was also satisfying. However, comparison product NO. l, NO
．． 5 was found to be unusable in the same experiment. Example 2 β-eucryptite powder with an average particle size of 6 μm was produced in the same manner as in Example 1.

Next, while stirring the β-eucryptite powder, dimethyltin dichloride was pyrolyzed at 600'C in the air and the gas was added to the gas.
A tin oxide film was formed on the surface of the β-eucryptite powder by intermittent contact. Next, these β-eucryptite powders having a surface film of tin oxide were mixed with 77% PbO and B2O3L.
2%, ZnO7%, Al2O33%, SiO21% low melting point glass (transition point 28σC, linear thermal expansion coefficient 11
Mix 20% of the mixture at 0 x 10-7°C and heat until it has fluidity. After cooling, the coefficient of linear thermal expansion, fluidity, electrical insulation, and thermal shock resistance were measured and shown in Table 2. show.

The measurement method was the same as in Example 1. In addition to Table 2, similar to Example 1, NO.
．． 7~NO. 9 has no abnormality, NO. In IO, cracks were observed on the glass surface.

Sample N with tin oxide film on β-eucryptite
O. 7~NO. Sample No. 9 had a lower linear thermal expansion coefficient as in Example 1, had good fluidity, did not cause deterioration of insulation resistance even at high temperature and high humidity, and had satisfactory thermal shock resistance.

However, NO. does not have a tin oxide film. 6 and the comparison product NOIO in which the thickness of the tin oxide film exceeded 0.8μ had poor glass flow button diameters.

It has also been found that if the amount of β-eucryptite added is 30% or more, the sealing properties deteriorate, high-temperature sealing is required, and reliability is lacking.

As described above, the present invention has various properties required as a low melting point glass for sealing used in electronic industrial parts, and contributes to improvement in quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a sample in which the resistance between the leads of the Surdip was measured. 1...Ceramic substrate, 2...Low melting point glass, 3A, 3B...Metal lead.

Claims (1)

[Claims] 1 β- having a surface film of tin oxide with a thickness of 0.8μ or less
Low melting point glass in which 30% or less of the eucryptite particles and the remaining 70% or more have a transition point of 250 to 400°C and a linear thermal expansion coefficient of 80 to 130 x 10^-^7/°C between 30 and 250°C. Expandable sealing composition. 2. A low expansion sealing composition according to claim 1, wherein the low melting point glass is a glass containing 70% or more of PbO and B_2O_3 in total.