JPS623066A - Ceramic composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to ceramic compositions, and particularly to improvements in ceramic compositions used in the manufacture of alumina multilayer wiring boards.

(Technical background of the invention and its problems) Conventionally, alumina multilayer wiring boards have been manufactured by a green sheet lamination method or a multilayer printing method.

In the former method, first, a ceramic raw material containing alumina as a main component is prepared and pulverized, this is made into a slurry, and an unfired green sheet is produced by forming the slurry with a doctor blade. Subsequently, a desired conductor pattern is formed on the green sheet by screen printing using a conductor base mainly composed of tungsten and molybdenum. Then,
A plurality of green sheets having conductor patterns formed thereon are stacked, heat-pressed and laminated, and then fired to produce an alumina multilayer wiring board. In the latter method, first, a green sheet is prepared in the same manner as described above, and then conductive patterns and insulating layers are sequentially and alternately formed on this green sheet by screen printing. Thereafter, it is fired to produce a ceramic multilayer wiring board.

By the way, in the ceramic multilayer wiring boards manufactured by each of the above-mentioned methods, if the insulation resistance between the layers is not sufficiently high, electrical short circuits will occur between the wirings, making the boards unusable for practical use. The value of the insulation resistance is preferably such that the volume resistivity (Rv) at room temperature is at least 2×10 1'Ωcm or more.

In the above-mentioned green sheet lamination method, since the green sheet i- serving as the insulating layer is relatively thick at 0.2 to 0 to 4 m, even if the volume resistivity of the green sheet formed from the conventional ceramic composition is about 1013Ωα, Since the interlayer insulation resistance is around 108Ω, some of them are put into practical use.

However, in the multilayer printing method, the thickness of the insulating layer is 0.0
Because it is as thin as 3 to 0.06 m, the volume resistivity of conventional insulating pastes made of ceramic compositions is 1.
In an insulating layer of about 0.013Ωα, the interlayer insulation resistance is 108
It is significantly lower than Ω and cannot be put to practical use. The thickness of the insulating layer formed by screen printing is generally 0.01 to 0.0.
It is 015m. As a result, the volume resistivity is 3X101
The maximum thickness of the insulating layer when screen printing using an insulating paste of a 3Ω1 ceramic composition is 0.015 m.
However, in order to form an insulating layer of 0.08 mm, it is necessary to repeat the printing and drying process 5 to 6 times. Additionally, along with this, the process of filling conductor paste into the peer holes for connecting the upper and lower conductor patterns is also required five to six times. This results in an increase in work time and an increase in the number of errors, which in turn leads to a decrease in yield and a rise in costs when manufacturing ceramic multilayer wiring boards, and furthermore, ^iI! This causes the problem of thickening.

[Purpose of the invention]

The present invention provides a ceramic composition that has high insulating properties and can be used as a green sheet or insulating paste in the production of ceramic multilayer wiring boards to significantly reduce process steps, improve yields, reduce costs, and further reduce the thickness of the film. It tries to provide something.

[Summary of the invention]

As a result of intensive research into ceramic compositions as starting materials for insulating layers and green sheets, the present inventors have found that the composition is mainly composed of alumina, titanium oxide, chromium oxide, silica, etc.
By adjusting the blending ratios of calcia and magnesia in a specific manner, especially titanium oxide at 0.1% by weight or more and less than 0.5% by weight, and chromium oxide at 3.5 to 4.5% by weight, ceramic multilayer substrates can be prepared. We have discovered a highly insulating ceramic composition suitable for green sheets and insulating layers.

That is, in the present invention, titanium oxide is 0.1% by weight or more and 0.1% by weight or more.
Ceramic composition consisting of less than 5% by weight, 3.5 to 4.5% by weight of chromium oxide, 3 to 6% by weight of silica, 0.5 to 2% by weight of calcia, 0.5 to 2% by weight of magnesia, and the balance consisting of alumina. It is.

Next, the reason for limiting each component constituting the ceramic composition and product of the present invention will be explained.

(1) Titanium oxide (TiOz) If the amount of titanium oxide is less than 0.1% by weight, uniform mixing with the entire ceramic powder will deteriorate. On the other hand, when the amount of titanium oxide is 0.5% or more, the interlayer insulation resistance decreases when used as a green sheet or an insulating layer.

(II) Chromium II oxide Cr203) If the blending amount of chromium oxide is less than 3.511%, unevenness tends to occur during firing, which causes problems in terms of strength. On the other hand, if the amount of chromium oxide exceeds 4.5% by weight, the living room insulation resistance decreases due to the relationship with titanium oxide, and the sinterability also deteriorates.

(III) Silica (S i 02 ) If the amount of silica is less than 3% by weight, the wettability and adhesion with the conductor pattern will decrease. On the other hand, if the blending amount of silica exceeds 6% by weight, interlayer insulation resistance decreases in relation to alumina.

(IV) Calcia (CaC)) When the amount of calcia added is less than 0.51 m%, sinterability decreases. On the other hand, if the amount of calcia exceeds 2%, interlayer insulation resistance decreases.

(V) Magnesia (Mac) When the magnesia content is less than 0.5% by weight, the sinterability decreases. On the other hand, when the blending amount of magnesia exceeds 2% by weight, not only the interlayer insulation resistance decreases, but also the grain growth during firing increases and the mechanical properties deteriorate.

[Embodiments of the invention]

Examples 1 to 6 First, six types of ceramic compositions having the composition ratios shown in Tables 1 and 2 below were prepared, and then these ceramic compositions were ground and mixed using a moving mill. Subsequently, to 100 parts by weight of these raw material powders, 20 parts by weight of trichlorethylene, n
- Add 10 parts by weight of butyral, 8 parts by weight of tetrachlorethylene, 5 parts by weight of tributyl phosphate, and 2 parts by weight of polypynylbosphate, mix in a ball mill for 24 hours, and then defoamer to prepare a green sheet raw material. did. Subsequently, green sheets with a thickness of 0.4 m++ were prepared from these raw materials by the doctor blade method, and then four sheets of each of these were laminated to form a green sheet with a thickness of 1.6 meters. Thereafter, a desired first conductor pattern was formed on the surface of each green sheet by screen printing using a conductor paste mainly composed of tungsten, and the green sheets were further dried.

Next, an insulating paste is prepared from the raw material powder obtained by vibratory milling and pulverizing the ceramic composition, and this insulating paste is printed on the surface of the green sheet on which the first conductor pattern is formed two or six times, and is dried. Thickness 0.03II11
Alternatively, an insulating layer of 0.08 m was formed. Subsequently, holes penetrating vertically through these insulating layers were formed, and the holes were filled with conductive paste using a screen printing method to form pier holes.

Subsequently, a second conductor pattern was formed on the insulating layer by screen printing using a conductor paste. The drawing shows the state after printing in this manner. In addition, 1 in the figure
is a laminated green sheet, 2 is a first conductor pattern, 3 is an insulating layer, 4 is a peer hole connecting the upper and lower conductor patterns, 5
is the second conductor pattern.

Then, the printed green sheet was fired in a weakly reducing atmosphere at 1560°C, and an insulating layer (thickness 0.03 JI
K and 0.08all) and volume resistivity were measured using a super megohmmeter (trade name: 5M-10E type, manufactured by Toa Denpa Co., Ltd.). The results are also listed in Tables 1 and 2. Note that Tables 1 and 2 show ceramic compositions in which the ingredients, especially titanium oxide and chromium oxide, are mixed in amounts that are outside the range of the present invention, and are prepared in the same manner as in the above examples. The evaluation of the substrate is also listed as Comparative Example 1.2.

Table 1 Table 2 As is clear from Tables 1 and 2 above, the insulating layer made of the ceramic composition of the present invention has a volume resistivity of 2X10
It has a high insulation property of 1ΩCH~7×101′Ω1, and therefore, even if the thickness of the insulating layer is made as thin as 0.03m, the interlayer insulation resistance can be 108Ω or more without causing a short circuit between the conductor patterns. On the other hand, the insulating layer made of the ceramic composition of Comparative Example 1.2 has a volume resistivity of 3×1013ΩcjlI
Or, the insulating property is poor at 2×10 13 Ωα, and therefore, unless the thickness of the insulating layer is increased to 0.08 s+LJ or more, it is impossible to achieve an interlayer insulation resistance that does not cause short circuits between conductor patterns.

In addition, although the above embodiment has been explained using a multilayer printing method as an example, the invention is not limited to this, and even when applied to a green sheet lamination method, sufficient interlayer insulation can be achieved even if the thickness of each green sheet is thinned. resistance can be obtained.

〔Effect of the invention〕

According to the present invention described in detail above, various effects shown below can be exhibited.

(2) Since the ceramic composition used as a starting material has high insulating properties, when applied to a multilayer printing method, the thickness of the insulating layer can be reduced, and the number of printing steps can be reduced to 2/8 to 3/8.

■By reducing the number of printing steps, troubles such as misalignment of the screen, falling during handling, and dust can be reduced by about 30%, and as a result, the yield from printing to firing can be improved, resulting in a significant improvement. Cost reduction can be achieved.

■The firing temperature can be lowered by about 20-30'C,
Energy saving can be achieved.

■ To obtain a compact, lightweight, and compact ceramic multilayer wiring board by reducing the thickness of the produced insulating layer or green sheet fired product using the multilayer printing method or the green sheet lamination method. I can do it.

[Brief explanation of the drawing]

The drawing is a cross-sectional view showing the state of the green sheet after forming the second conductor pattern obtained in this example. 1...I! Green Sea 1~. 2... First conductor pattern, 3... Insulating layer, 4... Pier hole, 5...
Second conductor pattern.

Claims (1)

[Claims] Titanium oxide 0.1% by weight or more and less than 0.5% by weight, chromium oxide 3.5-4.5% by weight, silica 3-6% by weight,
A ceramic composition consisting of 0.5-2% by weight of calcia, 0.5-2% by weight of magnesia, and the balance alumina.