JPS5913472B2 - Ceramic sintered body with glass window and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ceramic sintered body with a window glass having thermal shock resistance and a method for manufacturing the same.

More specifically, No. 5 relates to a ceramic plate-shaped sintered body having an ultraviolet-transparent glass window used as a cap of a ceramic package for an electronic circuit. This type of UV-transparent cap is an important cap for a storage package for a semiconductor non-volatile memory device that uses UV-erasing technology.
Conventionally, caps for semiconductor memory storage packages using ultraviolet erasing methods are of the type in which UV-transparent glass is welded to the center window of metal Kovar, or UV-transparent materials such as sapphire, Luca 15C]'nox, and quartz glass are used as they are. There is a type that is used as a cap.

In the former type, leakage occurred during a thermal shock test from the welded part of Kovar and UV transmission glass, and the airtightness was a problem. Of the latter type, when using sapphire and lukarox as a cap,
Although there is no problem with the thermal shock characteristic value, it has the disadvantage of being expensive. Furthermore, quartz glass still has problems with airtightness and breakage. 25
The present invention aims to eliminate the above-mentioned drawbacks.

The present invention uses a known ceramic sintered body as the substrate of the cap body, an opening (window) is provided in the sintered body, and glass is welded to the window. It is maintained in a constant pressure and compression state at 30 degrees below the fixation temperature. That is, the ceramic sintered body with a glass window according to the present invention is made by welding glass having a coefficient of thermal expansion 3 to 35 × 10 °C lower than that of the ceramic sintered body having a window, 35, and also provides a manufacturing method thereof. The present invention will be explained in detail below. As the ceramic sintered body used in the present invention, a sintered body made of alumina steatite, mullite, forsterite, beryllia, zirconia, etc. can be used.

For example, an alumina ceramic sintered body can be produced by a known method such as tape casting or pressing.
Manufactured by sintering at 1600°C. This shape is plate-like (second
(Fig. 5) or as a concave body (Fig. 5) having a continuous band-like raised stepped portion on the periphery, each having a preferably circular opening window formed in its center. Glass having predetermined properties is welded to the window of this sintered body. At this time, the glass fits smoothly into the window of the ceramic sintered body at room temperature without being damaged or chipped. Thereafter, they are fused at a predetermined temperature, at least the softening point or higher, preferably at a temperature higher than the bending point of the glass. Glasses that can be used in the present invention include ultraviolet-transmitting glass, ultraviolet-absorbing glass, infrared-transmitting or absorbing glass, electron beam, radiation-transmitting or absorbing glass, optical glass, and other known glasses. In one embodiment of the present invention, a ceramic cap with an ultraviolet-transparent window can be obtained using ultraviolet-transparent glass. The feature of the present invention is not that this glass is simply welded to a ceramic sintered body, but that the physical property relationship that should exist between the ceramic sintered body and the glass at that time has been clarified. be.

That is, according to the invention, the coefficient of thermal expansion of the glass is lower than that of the ceramic sintered body by a range of 3 to 35.times.10@-7 DEG C.-1, preferably 5 to 30.times.17 DEG C.-1. Based on the difference in coefficient of thermal expansion within this range, after glass is fused and cooled down to room temperature after passing through the fixing temperature, it will be subjected to appropriate compressive strain from the ceramic sintered body. This pressurized state improves the adhesion between the glass and the ceramic sintered body, for example, MIL-STD-883-1011-C (-
It can also withstand a thermal shock test of 65150°C (15 times in liquid). The thermal expansion coefficients (free state) of glass and ceramic ivy sintered bodies are generally graphed as shown in FIG. 1, and for example, the A glass of this example is shown by solid line 2.

On the other hand, the thermal expansion curve of the alumina ceramic sintered body used in this example is represented by the solid line 1.0 There is a difference in the coefficient of thermal expansion between these two bodies as shown in Figure 1, and there is a difference in the coefficient of thermal expansion during heating. Initially, the ceramic sintered body expands at a rate slightly higher than that of glass, but it eventually intersects the expansion rate curve 2 of glass. When heated further beyond this intersection K, the glass passes through the bending point Mg and begins to shrink; however, in reality, at temperatures higher than this, the glass expands laterally due to its own weight or load, forming a gap between the glass and the ceramic sintered body. Fill in and start welding.
In order to complete this welding, it is also possible to further heat the material to a high temperature of several hundred degrees Celsius or more. After completely uniform welding occurs, the ceramic sintered body is slowly cooled ξ, and the ceramic sintered body contracts again according to the curve, but at this time, the glass deforms freely according to the contraction of the sintered body until its fixation temperature Tm. It deforms (shrinks) without producing any special internal stress. However, when the temperature drops below the fixation point Tm, the glass is generally no longer able to deform freely except immediately after that until the transition point Tg, but it is surrounded by the surrounding ceramic sintered body and the external shape becomes a ceramic sintered body. is forced to contract according to curve 1. According to the present invention, the expansion rate of the glass A is within a certain range lower than that of the ceramic sintered body below its fixing temperature, so that after the temperature drops to the fixing temperature Tm, the expansion rate of the glass A is lower than that of the ceramic sintered body below its fixing temperature. It also shrinks only slightly. The free shrinkage curve of the glass below the fixing temperature is virtually given by the dotted line 3. Therefore, at room temperature, compressive strain ΔIA occurs in the glass, and compressive strain stress is generated based on this, resulting in a repulsive force from the center of the glass window toward the ceramic sintered body wall (outward).
Accordingly, the glass is welded to the ceramic sintered body with a constant pressing force. It is clear from the present invention that this pressing force is required to be moderate in order to impart thermal shock resistance, and that if the range is too large or too small, sufficient thermal shock resistance cannot be obtained. Summer. That is, the range is as mentioned above, the coefficient of thermal expansion is 3 to 35 x 10
A glass weld can effectively withstand a thermal shock test at a compressive strain stress corresponding to a compressive strain that is -7 DEG C.-1 less than that of a ceramic sintered body. Diagrammatically, the range of this expansion rate is a range with curve 4 as the upper limit and curve 5 as the lower limit for expansion rate curve 1 of the ceramic sintered body. In other words, curve 4 has an expansion rate difference of 3×1 with respect to the ceramic sintered body.
0-7℃-1, and 5 shows an expansion rate difference of 35×10-7℃
-1 is shown. Here, the absolute coefficient of thermal expansion of the glass is selected within the above range depending on that of the ceramic sintered body used, and conversely, when a glass with a constant absolute coefficient of expansion is required, By using a ceramic sintered body having an expansion coefficient as high as the numerical value in the above range, various combinations can be made over an extremely wide range of applications.

Here, the ceramic sintered body used as the ceramic package cap for electronic circuits, which is an embodiment of the present invention, may be a publicly known alumina, steatite, or mullite type material, and in that case, the thermal expansion coefficient is approximately 55 to 90×.
It is in the range of 10-70C-1. On the other hand, the glass has an ultraviolet wavelength of 2537 8 and a transmittance of 50% or more.For example, the borosilicate glass (4) and phosphate glass (B) shown in Table 2 have an expansion rate of α-39. ,52,×1
When using 0-7℃4 MIL-STD-883
-1011-C thermal shock test (see Table 1)
. However, for example, phosphate glass (Oα=98×10−
When using a temperature of 7° C.-1, the difference in expansion rate Δα becomes negative and reverses, and in this case, the test results in damage or leakage. Examples of the present invention will be described below.

Example 1 Ceramic sintered bodies (Fig. 2) having a hole with a diameter of 10 mm in the center of a square with a thickness of 1 m, 111 sides, and 20 m7!11 were manufactured from aluminite, steatite, and forsterite, and the results are shown in Table 2, respectively. Borosilicate glass (4) α=39X10-70C-1, transition point Tg4
2'C1 phosphate glass (B) (α=52×10-7
A glass disk with a glass volume of 1.08 to 1.2 for the volume of a hole with a thickness of approximately 17n71L and a diameter of 10m71Lφ was prepared using ℃-1Tg57 "C", and Δα=6, 10, 2, respectively.
After carefully fitting the glass discs into the holes of the ceramic plates at a temperature of 5.28 x 10-70C-1, they were heated to about 300°C above their respective softening points and welded under a carbon load.

Thereafter, it was slowly cooled to obtain a ceramic sintered body with a window glass. The sample was subjected to thermal shock resistance test MIL-STD-883-10.
The results of 11-C are shown in sample numbers 1 to 5 in Table 1.
In addition to the glasses (A) and (B) used in Example 1, phosphate-based glass (0α-98×10-7℃-1Tg-470℃ Using Δα=0, -32, -40, 41X10-7℃-
As Example 1, a ceramic sintered body with a window glass was obtained in the same process as in Example 1.

Table 1 shows the thermal shock resistance test results for Samples Nos. 6 to 9, and all of them failed. This provides a ceramic sintered body with a window glass having good thermal shock resistance.

However, it is of course applicable not only to ceramic substrates but also to other known materials having a similar expansion difference with glass.

[Brief explanation of the drawing]

FIG. 1 shows the thermal expansion coefficient curves of a ceramic sintered body and a glass. The horizontal axis shows temperature, and the vertical axis shows coefficient of thermal expansion. 1... Expansion rate curve of alumina ceramic sintered body, 2...
Glass expansion curve (4), 3...Virtual free contraction curve of glass (4) after welding, Tg...Transition point, Tm...Fixing temperature, Mg・・・・・・The bending point, FIG. 2 shows the ceramic sintered body with a glass window according to the present invention (
Fig. 3 shows a plan view thereof. FIG. 4 shows a cross section of an embodiment in which a sealing glass layer or metallized Ni plating and Au plating 8 is further added to the structure shown in FIGS. 2 and 3. FIG. 5 shows a cross section of an embodiment having a stepped portion on the outer edge of the cap. 6...Ceramic sintered body, 7...Glass, 8...Seal glass or metallized Ni plating and Au plating, 9
・・・・・・Stepped part.

Claims (1)

[Claims] 1. A ceramic sintered body with a glass window, which is formed by welding glass having a coefficient of thermal expansion 3 to 35 x 10^-^7°C^-^1 lower than that of the ceramic sintered body having a window. Concretion. 2. The ceramic sintered body with a glass window according to claim 1, wherein the glass is compressed under pressure by the ceramic sintered body at a temperature below its transition point. 3. The ceramic sintered body with a glass window according to claim 1, wherein the glass is a filter glass such as an ultraviolet transmitting or absorbing glass, an infrared absorbing glass, an optical glass, or other known glass. 4. The ceramic sintered body with a glass window according to claim 1, wherein the ceramic sintered body having the window is plate-shaped or plate-shaped with raised steps on the outer edge. 5. A ceramic sintered body with a glass window, characterized in that a glass having a coefficient of thermal expansion 3 to 35 x 10^-^7°C^-^1 lower than the coefficient of thermal expansion of the ceramic sintered body with a window is welded to the ceramic sintered body with a window. Production method.